Defaunation & Biological Annihilation
Defaunation in the Anthropocene
Rodolfo Dirzo et al., 2014
Since 1500, 322 species have gone extinct, largely driven by human activity. While this deservedly receives significant attention in conservation circles, this paper argues that focusing only on extinctions underestimates the loss of biodiversity. Equally alarming is the extirpation and/or significant decline in species abundance which, combined with extinction rates far above background levels, creates a pattern that is comparable to previous mass extinctions. Though the data is limited and attention even more scant, research suggests a similar trajectory for invertebrates, particularly within well-studied orders such as Lepidoptera (butterflies and moths).
While the paper argues this is a global phenomenon, it notes the loss is not random. The tropics, in particular, have a high rate of loss, even after factoring in the greater species diversity enjoyed by tropical regions. Large-bodied species creates a size-selective gradient. The paper uses IUCN (International Union for the Conservation of Nature) data to determine the loss of species, abundance, and geographic ranges of vertebrates and some invertebrates. Statistical models based on traits particularly susceptible to extinction (e.g., small geographic range, size, low reproductive rates, large home range, size, large body size) are employed to tease out patterns. One of the shortcomings of this, however, is recognizing how the risk of extinction is affected by how traits respond to pressures at the population level, rather than a global scale. Though we are getting better at discerning and predicting these patterns, offering some hope that methods can be developed to mitigate or reverse the impact, though we have done a poor job of this to date with the most common drivers (habitat loss, overexploitation, invasive species, and now climate change) increasing in intensity.
There is still much we don't know, though, such as how abundance and diversity loss will affect the composition and phylogeny of the remaining communities. Particularly problematic are gaps in our understanding of potential feedback loops from this loss of abundance, which in turn leads to gaps in our ability to predict and respond to it, emphasizing the need for intensive surveys to better grasp the scope of the problem. Some of the consequences include the loss of nutrient transport, pollination, pest control, water quality, and ultimately human health. This leads to a significant alteration in how ecosystems function, evolutionary changes among surviving species, and massive economic impact.
The paper concludes that we are in the midst of a "widespread and pervasive defaunation crisis, with far reaching consequences." While we know much about the impact to large mammals, evidence suggests smaller mammals and other animals are similarly being affected. Further research into these smaller, less understood animals and feedback loops is urged if we are to better understand the extent of the crisis and while extinction is import when considering impact and conservation efforts, the loss of abundance and diversity is equally important. We need to get better at predicting the traits and patterns that determine who survives in order to act, because we are fast approaching a tipping-point from which there may not be a recovery. Some suggestions for immediate action include mitigating animal overexploitation and changes in land-use, which could stave off the inevitable long enough to come up with comprehensive, long-term solutions. However, no solution is complete without addressing the ultimate cause of all these problems: human population growth and overconsumption, with a tacit acknowledgement of wealth and resource disparity. Fixing these long-standing human problems opens the door for long-term sustainability, else we risk fundamentally transforming ecosystem functionality.
Questions:
1) Why does the term defaunation remain a largely cryptic phenomenon? How would you define this term?
2) What makes certain lineages more susceptible to human impact (body size, geographic range, etc.)?
3) Which do you think is the most important driver of defaunation, anthropogenic climate disruption or habitat loss? Why do you think it is the most important driver?
4) Why has there been such a strong focus among the science community on species extinctions and not enough on population extinctions?
5) The paper ends by suggesting the end of humanity is writ large in the accumulation our own actions. The ultimate cause for many of the existential problems facing the planet (climate change, species extirpation/extinction, habitat fragmentation, pollution, erosion, decline in arable land, desertification, etc.) is human over-population and -consumption. Outside of extreme measures like genocide, what are some ways we can mitigate this? Do you think we will?
Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines
Gerardo Ceballos, et. al., 2017
This paper continues the conversation started in Dirzo et al. (2014). It suggests that we have been underestimating the severity of Earth’s sixth mass extinction. This underestimate largely traces to overlooking the accelerating extinction of populations. A number of analyses were used to calculate the degrees of range (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. These analyses support the view that the decay of vertebrate animal life is widespread geographically, crosses phylogenetic lineages, and involves species ranging in abundance from common to rare. The losses, however, are not uniform: some regions exhibit higher concentrations of species with local population extinctions than others.
The data indicate that Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. Future losses easily may amount to a further rapid defaunation of the globe. The likelihood of this rapid defaunation lies in the proximate causes of population extinctions: habitat conversion, climate disruption, overexploitation, toxification, species invasions, disease, and (potentially) large-scale nuclear war - all tied to one another in complex patterns and usually reinforcing each other’s impacts. However, there are other anthropogenic drivers, namely human overpopulation, continued population growth, and overconsumption, which need to be addressed and focused on.
Questions:
1) The paper emphasizes that its estimates are conservative due to insufficient data and unforeseen cascading events. What events do you consider likely that weren't already suggested in the paper?
2) Why do you think tropical, species-rich regions are seeing the largest population losses compared to other regions?
3) The paper suggests we have only 2-3 decades in which to respond to this rapid diversity loss. Do you think this is an accurate estimate? Why or why not? What actions do you think need to be taken?
4) While other animals have cause or contributed to extinctions, we are quite likely the only species aware of our impact (both short- and long-term) and capable of responding, yet we don't. Why?
5) The paper paints a stark picture of massive species and diversity loss as well as a corresponding economic impact. How do you think this new landscape will look, and how will it affect future human development?
by Clarissa Fernandez, Lyle Thomas, and Jason Lau
Rodolfo Dirzo et al., 2014
Since 1500, 322 species have gone extinct, largely driven by human activity. While this deservedly receives significant attention in conservation circles, this paper argues that focusing only on extinctions underestimates the loss of biodiversity. Equally alarming is the extirpation and/or significant decline in species abundance which, combined with extinction rates far above background levels, creates a pattern that is comparable to previous mass extinctions. Though the data is limited and attention even more scant, research suggests a similar trajectory for invertebrates, particularly within well-studied orders such as Lepidoptera (butterflies and moths).
While the paper argues this is a global phenomenon, it notes the loss is not random. The tropics, in particular, have a high rate of loss, even after factoring in the greater species diversity enjoyed by tropical regions. Large-bodied species creates a size-selective gradient. The paper uses IUCN (International Union for the Conservation of Nature) data to determine the loss of species, abundance, and geographic ranges of vertebrates and some invertebrates. Statistical models based on traits particularly susceptible to extinction (e.g., small geographic range, size, low reproductive rates, large home range, size, large body size) are employed to tease out patterns. One of the shortcomings of this, however, is recognizing how the risk of extinction is affected by how traits respond to pressures at the population level, rather than a global scale. Though we are getting better at discerning and predicting these patterns, offering some hope that methods can be developed to mitigate or reverse the impact, though we have done a poor job of this to date with the most common drivers (habitat loss, overexploitation, invasive species, and now climate change) increasing in intensity.
There is still much we don't know, though, such as how abundance and diversity loss will affect the composition and phylogeny of the remaining communities. Particularly problematic are gaps in our understanding of potential feedback loops from this loss of abundance, which in turn leads to gaps in our ability to predict and respond to it, emphasizing the need for intensive surveys to better grasp the scope of the problem. Some of the consequences include the loss of nutrient transport, pollination, pest control, water quality, and ultimately human health. This leads to a significant alteration in how ecosystems function, evolutionary changes among surviving species, and massive economic impact.
The paper concludes that we are in the midst of a "widespread and pervasive defaunation crisis, with far reaching consequences." While we know much about the impact to large mammals, evidence suggests smaller mammals and other animals are similarly being affected. Further research into these smaller, less understood animals and feedback loops is urged if we are to better understand the extent of the crisis and while extinction is import when considering impact and conservation efforts, the loss of abundance and diversity is equally important. We need to get better at predicting the traits and patterns that determine who survives in order to act, because we are fast approaching a tipping-point from which there may not be a recovery. Some suggestions for immediate action include mitigating animal overexploitation and changes in land-use, which could stave off the inevitable long enough to come up with comprehensive, long-term solutions. However, no solution is complete without addressing the ultimate cause of all these problems: human population growth and overconsumption, with a tacit acknowledgement of wealth and resource disparity. Fixing these long-standing human problems opens the door for long-term sustainability, else we risk fundamentally transforming ecosystem functionality.
Questions:
1) Why does the term defaunation remain a largely cryptic phenomenon? How would you define this term?
2) What makes certain lineages more susceptible to human impact (body size, geographic range, etc.)?
3) Which do you think is the most important driver of defaunation, anthropogenic climate disruption or habitat loss? Why do you think it is the most important driver?
4) Why has there been such a strong focus among the science community on species extinctions and not enough on population extinctions?
5) The paper ends by suggesting the end of humanity is writ large in the accumulation our own actions. The ultimate cause for many of the existential problems facing the planet (climate change, species extirpation/extinction, habitat fragmentation, pollution, erosion, decline in arable land, desertification, etc.) is human over-population and -consumption. Outside of extreme measures like genocide, what are some ways we can mitigate this? Do you think we will?
Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines
Gerardo Ceballos, et. al., 2017
This paper continues the conversation started in Dirzo et al. (2014). It suggests that we have been underestimating the severity of Earth’s sixth mass extinction. This underestimate largely traces to overlooking the accelerating extinction of populations. A number of analyses were used to calculate the degrees of range (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. These analyses support the view that the decay of vertebrate animal life is widespread geographically, crosses phylogenetic lineages, and involves species ranging in abundance from common to rare. The losses, however, are not uniform: some regions exhibit higher concentrations of species with local population extinctions than others.
The data indicate that Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. Future losses easily may amount to a further rapid defaunation of the globe. The likelihood of this rapid defaunation lies in the proximate causes of population extinctions: habitat conversion, climate disruption, overexploitation, toxification, species invasions, disease, and (potentially) large-scale nuclear war - all tied to one another in complex patterns and usually reinforcing each other’s impacts. However, there are other anthropogenic drivers, namely human overpopulation, continued population growth, and overconsumption, which need to be addressed and focused on.
Questions:
1) The paper emphasizes that its estimates are conservative due to insufficient data and unforeseen cascading events. What events do you consider likely that weren't already suggested in the paper?
2) Why do you think tropical, species-rich regions are seeing the largest population losses compared to other regions?
3) The paper suggests we have only 2-3 decades in which to respond to this rapid diversity loss. Do you think this is an accurate estimate? Why or why not? What actions do you think need to be taken?
4) While other animals have cause or contributed to extinctions, we are quite likely the only species aware of our impact (both short- and long-term) and capable of responding, yet we don't. Why?
5) The paper paints a stark picture of massive species and diversity loss as well as a corresponding economic impact. How do you think this new landscape will look, and how will it affect future human development?
by Clarissa Fernandez, Lyle Thomas, and Jason Lau
Rodolpho Dirzo, et al.
ReplyDelete1) Defaunation remains a cryptic phenomenon because it can occur in protected habitats, but to make things more complicated, some species can figure out how to work with the changing environment and thrive.
Defaunation means the loss of the species and populations of wildlife, and the decline in the number of individuals within these species or populations. This is a term like deforestation, the difference is that defaunation refers specifically to animal populations, where deforestation deals with plant populations. Both terms refer to decline in biodiversity.
2) Certain lineages are more susceptible to human impact due to well established patterns such as body size and range sizes, but also to small geographic range sizes, low reproductive rates, large home range size.
3) In my opinion, the most important ones are the losses due to decreased ecosystem function. The animals are no longer present to perform their services, such as decomposition of plant material and fecal matter, or pollination necessary for food crops and the generation of seeds, and water quality.
4) Population extinctions are less evident than species extinctions, even though they are more important to ecosystem functioning. Effects of population extinctions are poised to become more evident as the numbers of individual animals, insects, birds, etc. decrease.
5) If we are not careful, there will be a nuclear event soon, which will drastically reduce the human population, and will further reduce it long-term due to radiation effects. Reduction of the general global human population is needed to put balance back into the ecosystem. Humans, the most successful invasive species on the planet, are not capable of reducing its numbers to a sustainable quantity, as we are hardwired to reproduce and to overexploit all resources available to us. If we continue as we are, this will result in the reduction of edible food, potable water, breathable air, and other resources that we have become dependent on, causing widespread famine, disease and ultimately reductions in our population numbers.
Gerardo Ceballos, et al.
1) After the decline of the human population due to our overexploitation of resources, animals, plants, water, etc., a balance may come back to the planet. In this balance, there will be only a small role for humans, as they exist today, if any role at all. Humans may go extinct on this planet before all is lost and life on this planet may continue to another era, epoch, etc. without us.
2) Tropical regions are experiencing high species population losses because they are regions that are preferred as human habitats. There is a higher human population density in these areas.
3) Our resources have a finite limit, and if humans continue to reproduce at the rate we are, these resources will be depleted, resulting in a major population crash, possibly a human extinction. To make our environment sustainable, the first thing we need to do is drastically reduce the human population. Next is to reduce our dependence on non-renewable resources to make our environments habitable.
4) We do not take actions capable of reversing the situation because we, as a species, are hardwired to reproduce as fast as we can and to exploit all resources that are available. This is part of our survival mechanisms instilled in our DNA and our collective psyches.
5) Human populations will become colonial, clustered in areas that can support them. Humans may become extinct, or become very nearly so. The overall landscape will be starkly devoid of plants and animals until these can evolve and re-establish themselves. Human populations will grow as the landscape does, continuing our exploitation. There may not be enough of us to regain our former dominance. If there is a nuclear event, humans may have to live in protected spaces until evolved enough to survive on the surface of the devastated earth again. Humans will not be the same as the species that we know now.
Rodolfo Dirzo et al. 2014
ReplyDeleteI would define defaunation as the loss of animals from their ecosystem. This term remains a largely cryptic phenomenon because it can occur in any habitat no matter how much control we, as humans, may have on it. Certain lineages become more susceptible to human impact including large body size and specialized animals. Animals with large body size are more subject to extinction because as humans take over land there is less and less land for these large animals to live and specialized animals have no where to go if their ecosystem is taken out. The more important driver of defaunation is habitat loss because without any habitat, there’s no way for the animals to live. I don’t think there is much of anything that we can do to mitigate this human over-population and consumption. Humans reproduce and reproduce without much of a thought about what the future may hold and what happens when we exceed the limit population for the planet. There isn’t much we can do except to educate everyone about over population and what it can do to our species and hope that everyone works together and does the right thing to bring down our population size.
Gerado Ceballos et al. 2017
I think that tropical, species-rich regions are seeing the largest population loss compared to other regions because this is an area where humans want to live. There are also many species already located here because of the area and how many other types of fauna and climate is located here and so because it is a great habitat already, humans are trying to take it over for themselves. With the way things are moving so quickly now with global warming and all its effects I don’t think this estimate is too farfetched. I think that global warming as somewhat of a snowball effect on the world and if we don’t change quickly by moving to renewable energy and recycling, we are going to lose control and lose a lot very quickly. I think that we have no responded to our impact simply because a lot of people aren’t truly educated or want to turn a blind eye to the problems we are causing. Everyone needs to learn and be educated about what we are truly doing as a species to the planet and to other animals. I believe that the new landscape will be very scarce of species, including humans. Humans may even go extinct at some point and after that it will take time for the scare amount of species still left to evolve and adapt to the new world that we are creating.
Dirzo et al. Paper
ReplyDelete1.Defaunation remains a cryptic term, because it does not generate enough “buzz” when one reads about it in a research paper or when one hears it on the network news shows. Extinction grabs people’s attention because ever since they were children they have learned about the dinosaurs going extinct and that’s the word every kids’ show and book uses as it makes the whole thing sound very climatic and exciting; whereas defaunation sounds too “sciency” and does not grab a reader’s attention even though they may as well be the same thing. Defaunation if I were to define it, would mean the loss of an animal from an ecological zone permanently, for example when their range in cut in half or when a population dies.
Cerballos et al. Paper
4. We as species/people/intelligent beings don’t respond to our impact on the world, because we are used to certain levels of comfort and realizing what those comforts actually cost the biosphere as a whole could severely damage a lot of economic markets, and cause ordinary people to give up goods and services they are used to having. There is a phrase that goes like this: “generosity tends to stop at your front door” meaning that people are generally very generous with their time and maybe money but they are very reluctant to give up anything they actually own such as phones and cars, and as long as this crisis does not affect their present actual ability to use and possess these comforts the common person will not change their behavior to match the needs of our planet as their needs come before everyone else’s. This comes from our base animal instincts that confine us to hoarding resources and wealth in order to show our dominance to competing member of the same sex and to display for potential mates of the opposite sex. This will never change, as it is bred into every animal mind in existence.
Rodolfo Dirzo et al., 2014
ReplyDeleteThe term defaunation can be defined as the loss of animals or decrease in animal biodiversity in natural ecosystems. Defaunation is considered a cryptic phenomenon because without extensive surveying we are unable to fully understand how species diversity is changing. Sadly, certain species are greatly affected by their body size and geological range. If animals are large and have a small range human have a much easier time killing them. I personally think that habitat loss is causing more defaunation. This is the driver because species are being pushed out of their natural habitat and if they aren't able to adapt they can't survive. I think there is more information on species loss than on population extinction because species loss is easier to categorizes. I don't think scientist are as concerned with biodiversity loss as they are with large amounts of species loss. I think if population and species extinction continue as they are we will be living in a world without many keystone species left. I think plant and animal communities will become homologous with little to no diversity.
Gerardo Ceballos, et. al., 2017
I think tropical species rich places are seeing the largest loss in populations because they have very specific habitat needs. These species can not easily adapt to new climates or drier habitats. I think the estimation of 2-3 decades is accurate if we do not increase habitat destruction. Actions that need to be taken is more regulations on deforestation of the tropics and start using more renewable energy resources such as solar energy.
ReplyDeleteRodolfo Dirzo etc al. 2014
The term defaunation is labeled as cryptic because as the authors suggest, it can occur in protected habitats, and yet some animal species are able to persist in highly modified habitats. Defaunation should be defined as the loss of species and populations of wildlife as well as local declines in abundance of individuals. I believe one of the biggest characteristics that make certain lineages susceptible to human impact is an organism being specialized in where it resides. Because they are specialized the organism cannot keep up and adapt to human impacts to the point where they have a decline in numbers faster than they can reproduce. The two drivers mentioned leading defaunation are equally as detrimental in my opinion. Habitat loss may have more of an immediate impact allowing animals to quickly decline in numbers but in the contrary anthropogenic climate disruption can ultimately lead to the same process as habitat loss in typically a slower manner. In my opinion species level extinctions are the foundation line to understanding the bigger picture being population level extinctions. Although population extinctions are less focused on as opposed to species level extinctions, if we can determine how the species level extinctions effect a habitat this may give us an insight as to what a population level extinction would do. Unfortunately, I think the issue of existential problems due to human over population and consumption cannot be fixed without education. In my opinion, I don’t think there is enough comprehensive awareness in the community regarding this issue. One immediate solution to the issue should be education. It should be taught starting in high school and should be a point of emphasis in college undergraduate biology courses. With education, I believe humans can start to reverse the problems of over population and consumption before it is too late.
Gerardo Ceballos et al. 2017
Tropical species rich regions see the largest population loss due to the fact that many of the species in that region may be specialized. Unfortunately, a big downfall to being specialized is that in most cases you can't adapt to human impacts quickly enough to allow your species to survive. In most cases death of species quickly outweighs reproduction resulting in extinctions. Humans that prefer to live in these tropical regions quickly diminish already existing habitats of other organisms resulting in their removal from the region. I believe the estimate of two to three decades to respond to the rapid diversity loss may be too late due to the alarming rate of destruction humans are causing on habitat loss. Humans need to be more aware of how they are affecting the climate and destroying habitats by over population. Not only do these problems have direct effects but they can cause many indirect effects such as plants not being able to efficiently reproduce because their pollinators are becoming alarmingly low in numbers. Again, I think education is going to play a key role to bring awareness and help bring a solution to the big problem at large. The lack of education is a major factor as to why humans as a whole have not responded as sufficiently as they could to short and long term effects contributing to other organism’s extinctions. As a result of the picture the authors painted in regards to massive species and diversity loss, I think the earth will be depleted of many species and resources. Like other mass extinctions the earth will need time to recover. Humans may or may not be a part of this recovery, but the organisms that will be able to be apart of the new landscape will be the ones that can be supported by the environment. Personally, I think so many ecosystems will be interrupted that humans probably will be scarce and the organisms that is most opportunistic will establish itself quickly enough to create a new dominant organism.
Defaunation is described as cryptic, because it cannot be easily assayed. Unlike deforestation, which can readily be assessed with satellite imagery, defaunation requires going into the field and counting animals. Defaunation can be defined as the reduction or elimination of niche animals within a geographic area. This concept is the basis for the studies by Dirzo et al. and Ceballos et al. Their hypothesis, that massive reductions in animal populations are a precursor to mass extinction, is rational when viewed in the context of interdependency of organisms in an ecosystem.
ReplyDeleteIt is my opinion that defaunation, deforestation, and pollution of the environment is a function of human population size and cultural traits. As individuals, we are far more likely to conform to general practices than to eschew comforts and luxuries that result from the exploitation of distant lands (five to ten miles is distant enough for most people). The culture of mass consumption has been exported to all parts of the globe, and enhanced by a plethora of technologies. It is unlikely that this trend will be reversed. However, if our knowledge of ecosystem dynamics, our prudence to implement reasonable policy, and our advancement of technology keep pace with extinction rates, it is possible that humans will survive the extinction event. The entire biosphere would be managed, and would probably be a lot more insipid.
Dirzo et al.:
ReplyDelete3) I think it's hard to choose just one important driver of defaunation. There are many examples where both anthropogenic climate disruption and habitat loss have shown to change biodiversity. The honeycreepers in Hawaii are slowly being over run by diseased mosquitos. As the climate warms, the birds try to move up in elevation, but the mosquitos follow. If this trend continues, the honeycreepers will no longer have a place to move and will become extinct. Habitats are also being lost because of deforestation, urbanization and digging for fossil fuels. This is a direct driver because we are literally taking the homes away from these species whereas warming the climate is slowly changing the world.
Ceballos et al.:
2) I believe species-rich regions are seeing the largest population losses because they have more to lose. If there are more species packed into a smaller area, they have to share those resources. Each little ecosystem acts as a complicated network. When species begin to decline and go extinct, their role in the ecosystem vanishes and other species relying on those roles begin to take a hit. In a region where there are less species, the other species can have more resources and the network probably isn't as tied together as it is in the densely rich regions.
4) Although we are aware of the long-term impact of our actions, I think it is hard for us to truly believe that we are capable of such destruction. It's like "we can't believe it until we see it" sort of situation. I believe it's also easier to say "not my problem" and let future generations deal with it. It's like the bystander effect, if there are so many people around, one of them will surely act but as the population increases, the likelihood of someone responding decreases. It is also difficult to make progress when a big portion of the population does not believe that the climate is changing and that we are the cause of it. So until we all agree and try to come up with a solution, I'm not sure much progress will be made.
Rodolfo Dirzo et al. 2014
ReplyDeleteI think of defaunation as the decline of species from their natural habitat. The human species has been affecting mammals of all sizes since we first began to evolve. In order to provide mass resources to products in high circulation we have almost destroyed all of the large forests on the globe. In order to pave the way for urbanization, we have obliterated animal homes, food resources, migration patterns, etc. We have also brought genetically engineered species into the mix along with uprooting large populations of species from their natural habitats to areas they are not necessarily adapted to. All of these factors along with many more go into defaunation of species of all sizes.
Gerardo Ceballos et al. 2017
I agree that we, as a collective whole, have been greatly down playing the severity of the 6th mass extinction. I do think that we only have a few short generations to start making a difference. If we do not, then I think that earth will become uninhabitable for the human race. I think that the changes that are happening are happening so quickly that most species will not have time to adapt to survive.
The general public is usually more concerned with the loss of entire species because they are unfamiliar with the effects of extirpation or population declines. They are more familiar with terms like extinction rather than defaunation. I would define defaunaing as the loss of fauna from an ecosystem. Scientific research centers around endangered species and extinct species because the government will give out more money in grants to research around these sets of animals and plants because the public agrees it is important. Giving better knowledge to the government and the public about the general loss of biodiversity and the negative impacts that go along with it would be extremely valuable and important.
ReplyDeleteRodolfo Dirzo et al. 2014
ReplyDelete1.) First, I would define defaunation as the removal of animals from an ecosystem. In defaunation, we are likely to see a decline in the abundance of the species as well as their disappearance from an ecological community. Both of which result in a loss of biodiversity. As the readings states, the reason why defaunation has been labeled as a cryptic phenomenon is because it has been observed that some species decline in protected habitats while some species adapt and thrive in the altered, modified habitats that humans have produced. Furthermore, I believe that not enough people understand what it is or recognize the significance it has on ecosystems.
2.) Size and geographic range surely make certain lineages more susceptible to human impact. Research suggests that from the time hominins have existed, more specifically humans, large sized animals have faced rapid declines in population size and even higher extinction rates. If an animal has a wide geographic range, it is more likely to persist than an animal who has a small geographic area, whom would be more likely affected by human interaction with its natural habitat. One other thing that may make certain lineages more susceptible to human impact would be whether a species is a specialist or not. Specialist species have either specific diets or can only survive in a compact range of environmental conditions. Therefore, it is reasonable to think that alterations of natural conditions and the environment, would negatively impact specialist species.
3.) In my opinion, I think the most important driver of defaunation is anthropogenic climate disruption. I think its more relevant than habitat loss because it not only impacts natural habitat, it can also impact the synthetic/ modified habitats humans have created.
4.) My idea is that there are not enough scientists looking at the overall picture. In other words, I think individuals tend to follow/ observe a specific species or class of animals instead of also looking at other animals from different classes.
5.) In the short run, I think humans should continue to build vertically and not horizontally (more skyscrapers and less suburbs) and include more vegetables in our diets. I mean let's face it, people who consumes meats are not going to stop. Eventually, I think our long term solution is to look to the stars. We need to construct a way in which we can build on another planet.
Gerardo Ceballos et al. 2017
2.) I think that tropical, species-rich regions are seeing the largest population losses because the animals tend to specialists. Specialist can only survive on a specific diet or at certain environmental conditions. When humans disrupt such confines, the species are at risk of annihilation.
4.) There can be no greater arrogance nor reason when one reaches maximum superiority. Humans, being the dominant species on the planet, are the most stubborn and greedy organisms a planet could create. I think too many people have conceived the idea that we can always fix our problems later. We live such short lives that we do not care enough. We care more about our own wealth than we do for the wellbeing of our future planet.
5.) I think the landscape will homogenize. Eventually, no matter where you go in the world, all fauna and flora may appear the same. By the time key positions in power realize the severity that such disasters create, humanity may be faced with a huge economic disaster, trying to reverse or slow problems that could have been resolved a long time ago.
Rodolpho Dirzo, et al.
ReplyDelete3) Which do you think is the most important driver of defaunation, anthropogenic climate disruption or habitat loss? Why do you think it is the most important driver?
--i think that both factors are relevant in evaluating defaunation. Climate disruption and habitat go hand in hand in many instances, such as fauna in the Alaskan tundra, which are being impacted by both climate change (its getting warmer and they have to move more north ) and habitat loss (we are plowing down forests for oil and resources). the importance of either factor is dependent on which environment we are discussing, as the desert dwellers and rain forest dwellers are impacted in different ways which lead to loss of species diversity.
Gerardo Ceballos, et. al., 2017
4) While other animals have cause or contributed to extinctions, we are quite likely the only species aware of our impact (both short- and long-term) and capable of responding, yet we don't. Why?
--Humans and our society is individualistic (mostly), therefore we think about our gain and our lifespan before we think about others. I think it's hard for people to think beyond the impact on themselves,because if they wont see the change of the environment in their lifespan, a lot of people don't care. Also i feel like many people don't feel like they can make a difference as one person, therefore they chose not to change, however if everyone has this mindset nothing changes. I spoke with a friend about climate change and little things we can do, like drive less or use more fuel efficient cars, consume less (energy, meat,etc), and be less wasteful ,but they thought that such small changes wouldnt make a difference. I feel like the movement has to be as a collective... that the government has to establish a change, however in the land of the free, it is hard to force people to do anything that might cost them money or time, or make them change their lifestyle a little. so in short, humans don't change because they don't want to.
I think the most significant factor contributing to perpetual degradation of Earth’s biodiversity is, ironically, the diversity of humans and human culture. People dominate the entire globe, and while many of us recognize need for change, progress is unlikely to happen to the extent the planet needs. In fact, amongst humans the term “progress” is subjective at best. People of different cultures, or people of different religions and lifestyles within the same culture, have differing levels of education and differing ways of organizing priorities. While we may share many local ideals and norms, the concepts of right and wrong are as diverse as culture on a global scale. Despite our best intentions, our differences will likely always divide us, so I personally find optimism in maintaining effective communication with others.
ReplyDeleteAs we discussed in class, Americans have habits that we would be hard-pressed to break. To refer to an example used in former discussions, we tend to dispose of a significant amount of plastic straws that have become a harmful component of our oceans. When a person visits a restaurant in America and orders a drink, wait staff tosses straws down on the table or brings drinks with straws pre-placed. At self-serve places, plastic cups are given out with plastic straws available, as well. In an effort to be responsible for our actions, we can refuse to use a straw, bring our own drink in a tumbler or reusable bottle, ask if any dish-washable cups are available, or even forego having a beverage altogether. However, once wait staff tosses a straw on a table, unless the straw is handed back, it will likely be thrown away when the table is cleared. If the straw lands on a table wet from being cleaned and begins to soak, wait staff will likely not take that straw back or will throw it away if the person at that particular table does not use it. If straws come pre-placed in a glass, it will go to waste and be thrown away anyway if not used. If we rudely or judgmentally request to forego having a straw or plastic cup, we are being unfair to wait staff and may receive lower quality service throughout our experience. If we do so pleasantly, we have the chance to explain why and engage in pleasant conversation throughout our experience. I feel the same way about talking about politics. Therefore, I believe our ability to promote culture change is within our communication with others. We have the opportunity to share the reasoning behind our choices with others when we learn to communicate effectively. I don’t think we will ever be able to convince an entire culture of people, let alone different cultures of people, to enact mass change without the ability to understand those other cultures and appeal to them in helpful ways. Maybe all it takes is a pleasant conversation with a waiter/waitress about a straw that can lead a stranger to think more about American habits, and maybe we should realize that, instead of being hard on others for their choices or for inconveniences when trying to make our own choices, we can simply share the reasoning behind what we choose, express pleasant interest in the choices of others, and hope someone is better off for the conversation.
Rodolfo Dirzo et al., 2014
ReplyDeleteI would define defaunation as the overall decrease of biomass and biodiversity, biomass being reflected by population numbers and biodiversity being reflected by species numbers. Both of these factors are related to each other and together define defaunation. Large body size and limited geographic range are two factors that certainly would predispose a lineage toward being more susceptible to human impact. Other lineages negatively impacted would include organisms adapted to highly specific niches which are vulnerable to human tampering. I think extinctions have been focused on because they are more sensational and easier to comprehend than simple population declines. It is more dramatic to state a species has gone extinct than to say they have lost 40% of their population from 10 years ago, and it is also easier for people to image extinction than a 40% loss. Also, extinction is permanent whereas population declines could be recovered from and therefore people may not concern themselves with declining numbers of a specific organism. Mitigating human over population and consumption would require a huge cultural shift as well as the technology and infrastructure to enable for environmentally friendly consumption. I believe it is possible to humans to make this shift if the culture swings toward eco-friendly outcomes, but the technology needs to be present so people are able to be eco-friendly while still having the comforts they are accustomed to. There needs to be a focus in the technology sector for green products, but mass consumers need to instigate this shift in focus by voting with their dollars.
Gerardo Ceballos, et. al., 2017
I think tropical regions are experiencing high population losses both because there are large numbers of organisms living in tropical regions and because tropical organisms tend to be particularly sensitive to temperature changes and cannot mobilize to new habitats due to habitat destruction. It seems that the landscape of the future will be greatly homogenized, with the only wildlife present those that cohabitate or are cultivated by humans. The biosphere will largely be made up of livestock and humans, and the vegetation will primarily be agricultural fields. I think we don’t do anything to stop human impacts because we are able to distance ourselves from the destruction we are creating. The exchange of money for goods creates distance between an individual and all of the waste and pollution that was a direct consequence of the product they purchased. Education of how certain products harm the environment is essential to increase awareness for individuals who simply aren’t aware of how their actions may be harming the biosphere.
Rodolfo Dirzo et al., 2014
ReplyDelete1) Defaunation is a pretty unspecific term in general. The general definition I would give it is the decrease in biodiversity of animal life, just like deforestation is the decrease in tree life. But defaunation does not cover something like the area it occurs, what sorts of fauna are disappearing, and so on.
2) Body size is the first thing I think of, but human impact is generally non biased. Species that are amphibious such as axolotls and frogs, all the way up to rhinos and elephants, are all affected. So I don't think there are a lot of certain lineages that are especially susceptible.
3) This is difficult. Climate change/disruption can easily lead to habitat loss, such as in the arctic, so I suppose habitat loss would be the biggest driver. Less area to live in means less resources, less room to thrive, and so on. It also pushes different species closer together, and there simply isn't enough habitat for every single one.
4) There is only so much manpower, funding, and only so many scientists in the world. The power they have is very, very limited. Focusing on preserving a species keeps it alive, however small the population size (even if the effort does not pay off). Focusing on a population and pouring resources into just one can leave other species vulnerable.
5) As long as money exists, we're doomed. No health care, no relief for poverty, pedophilia and gun violence is rampant...hell no. At least the US is screwed. The rest of the world can go on without us as far as I'm concerned. It's what we get as a whole for the war on science right now.
(Guess who has no hope for the future)
Gerardo Ceballos, et. al., 2017
1) We don't have eyes everywhere at all times due to a lot of remote areas- there can be areas that we haven't even looked at yet that have populations that have been hunted by indigenous peoples, like they have been in the past. There are also plenty of things that could be happening in secret that we don't know about. I am not sure about an answer for this question, the best I can come up with is that I simply do not know.
2) Tropical regions typically are near or on islands, and even if not, the species that live there are very well adapted to a very specific environment. When it changes drastically, they struggle the most to thrive.
3) I think that responding quicker would be more ideal...the longer we wait, the worse this gets. There need to be way more regulations on corporations that interact with the environment, and energy especially needs to be changed to solar, wind, tides, etc.
4) Money.
5) Eventually the landscape will be barren and ugly, I think, we will have less wildlife, and we will either start to die off rapidly or we will exist in a world almost completely devoid of nature.
I think defaunation has remained a cryptic phenomenon as it has differed from just extinction of large mammals. Defaunation has shown an effect on the whole community and changed the amount of all animals and not just large mammals. The most important driver of defaunation I think is the loss of habitat structure. This seems to be the main cause of why mammals have disappeared as much of the land has been disrupted by humans who are using the land for other things. Deforestation is a large component of habitat loss where animals lose their homes, in need of finding another one. On the other hand climate disruption can also be large component of defaunation as forests are cut down and destroyed, the climate changes as a result of different amounts of carbon and oxygen are in the atmosphere. Ultimately, I think defaunation can be a cause of both climate and habitat loss.
ReplyDeleteI don’t know necessarily if 2-3 decades would be enough time to respond to the diversity loss. I think something can be done in order to change how fast animals are going extinct like changing how much land is being disrupted from humans to create more buildings. If we stop or slow down how much land is being changed I think it will allow animals to change how fast they are going extinct. I’m not sure what can happen in 2-3 decades as land before humans has changed drastically without our help. I do believe there can be a change, but I don’t know how much and I don’t know what would be a reasonable amount of time.
Rodolfo Dirzo et al., 2014
ReplyDeleteJust like what we learned in class, large flightless birds are going to go extinct from hunting and predation from human impacts. With smaller ranges or more spaced out ranges, any type of decrease in their range will limit the species to a smaller population size and a decrease in their gene flow for future generations.
Gerardo Ceballos, et. al., 2017
With the destruction from deforestation, there are large habitats that have many different niches for organisms that are being destroyed. In tropical, species-rich areas, the organisms are adapted to that specific environment and cannot expand their range to outside of that area. This makes it easier for species to die off from any sort of environmental change that can happen from human interactions.
Rodolfo Dirzo
ReplyDelete1. According to an online search defaunation is defined as a loss of animals from ecological communities. However, it seems like this term may lead to confusion because it includes both the extinction of species and the decrease in abundance of the organisms in the community. Catch all terms like defaunation can become cryptic because they lack specificity.
2. In the past when hominins first migrated across the continents large body size made species more susceptible to predation and eventually extinction due to humans. It seems though that there is less and less selectivity against what is currently threatened as human’s population increases exponentially and pushes into all areas of the globe.
3. I think habitat loss is the biggest driver of defaunation because as pointed out in class many organisms have survived more drastic changes in climate change because they had access to large habitat ranges that they could relocate too. Now as habitat loss increases with the expansion of human impact organisms not only lose access to their ecological niches, but also they lose the ability to move in order to survive the changes in climate.
5. I don’t have much hope that human kind will successfully migate the loss of animals. It seems like we would be needing to take huge measures to start protecting and preserving surviving populations of endangered species now as well as addressing the issues with CO2 emissions and climate change. However, the current political situation in the U.S. doesn’t give me much hope for positive change. Additionally, I think world peace would have to be achieved in order for the human species to come to a mutual decision to try and preserve life on this planet other than ourselves.
Defaunation in the Anthropocene
ReplyDeleteRodolfo Dirzo et al., 2014
2. As we have discussed in class, there are multiple factors that influence the susceptibility of organisms to human impact. For example, having a large body size has many consequences. These animals have larger energy requirements, are often more sensitive to environmental changes (temperature), etc., which may result in vulnerability. Additionally, rarity, specialization, or being poorly adapted to human activity may increase susceptibility to negative impacts.
3. I believe that habitat loss has a more drastic influence on defaunation as it is relatively sudden, extreme, and irreversible. While climate disruption is no doubt an important contributing factor, I believe that this happens at a slower rate and may give animals time to migrate or adapt to changing environments, as long as the changes aren't too drastic. However, when massive stretches of land are turned over for agriculture and industrialization, the animals have no real escape route. Increasingly smaller patches of habitat cannot effectively sustain large populations.
5. I am not very hopeful that we will be able to rectify the damages that we have caused. For one, our country as a whole is extremely uneducated on the matters at hand. I don't believe that many people know the extent of the destruction that we have had on the Earth, or many claim that the problems don't even truly exist. In order to mitigate these changes, we would have to not only educate, but also to gain enough people who actually WANT to make an effort to make changes. This is because to truly generate change, we would have to make large alterations in our everyday lives: in the ways and amounts that we consume, the ways that we put up entire cities in an instant with little regard for the wildlife, etc.
Gerardo Ceballos, et. al., 2017
2. I believe that this relatively large population loss in tropical regions is due to human settlement in tropical locations. This is a highly preferred location for humans to inhabit, which results in widespread habitat loss for animals. Although they may have high species diversity, this does not protect animals in this region from massive loss of populations.
3. Considering the rate of past extinctions that we have learned about so far, I do believe that this is a reasonable estimate. We are increasing in population at a seemingly exponential rate, and with this population increase has come extreme technological advances and widespread industrialization. If we wish to bring the rapid decline in diversity to a halt we will have to act in the near future.
I think defaunation has remained a largely cryptic term because we haven't yet extensively researched and surveyed the causes of it. Defaunation is the loss of species diversity in an environment/ecosystem, but research has focused less on it than on extinction at a global scale. The Dirzo et al. 2014 paper raises an important point that biodiversity loss is not only experienced when a species goes extinct at a global scale but also through local extirpations or decrease in faunal populations. In the modern world, many evidence shows that certain niche specialization and small geographic range tends to increase a species' risk of extinction. Because habitat loss is such a significant factor in determining a species vulnerability, a smaller, more specialized habitat or niche that can only be found in a small geographic range puts those species at a much higher risk for extinction.
ReplyDeleteIn my opinion, habitat loss is a more important factor in determining extinction vulnerability than anthropogenic climate changes because I think the effect on resources is greater with habitat loss. While climate change presents challenges for species to adapt to, its effects tended to be ameliorated by migrations to areas where its effects were less significant (animals moved inland, moved to higher elevation, etc.) However, due to habitat loss, the ability to easily move to a more suitable habitat is lost due to fragmentation and urbanization. Therefore, the effects of climate change today might very well have a more significant impact on species survival than it did in the past, but only because habitat loss will prevent successful migration. In addition, habitat loss also means a loss in available resources, so the land available to species won't be able to support a large population.
I really don't know the answer to human population size and overconsumption. I think some sort of massive event would have to take place in order to change the habits of many people. The issue of rising population is significant, but I don't know how successful attempts to mitigate its effects would be because we have evolved to want to have children and to want to care for them. Having children to raise is a desire for many people, and I don't know how it would work if we tried drastically changing this. I wish I had a better answer.
In terms of desired environment, I believe the tropics are most desirable for many humans because of the temperature, rainfall, and ability to grow crops. So, it makes sense that we would see a higher biodiversity loss here compared to other regions. In addition, the tropics have more resources to exploit, such as rainforests that are exploited for wood and land for farming. I don't have enough education in this area to determine if the estimate for 2 - 3 decades is the time-limit we have before this biodiversity loss becomes irreversible and ends with many unwanted consequences. It is safe to say that the resources that we rely heavily on today are finite and will not last us indefinitely. I think there will be a turning point in the future where human activity might cause a feedback loop of negative consequences for us and the environment, but I don't know if the estimate from Ceballos et al. 2017 is accurate.
Because the computer cut off the rest of my response:
DeleteI believe there are a variety of reasons why we don't respond quickly or decisively with our impact on extinctions. One, I think education specifically on how we cause extinctions is lacking. I think that many people may know that humans have caused species extinctions before, or have at least heard that people have caused extinctions (even if they don't believe it). I think that getting more specific knowledge as to how humans have led to extinction is a first step to getting more people to accept our role in modern extinction and to starting a global conversation as to possible solutions. Two, endangered animals in developing countries are still put at risk because of poachers or people who need money/resources for their livelihood. Economic impacts within human society have sometimes gotten in the way of necessary conservation efforts for certain species, which then leads to a tug-of-war between helping endangered species or helping desperate people. In addition, poaching (such as with tigers in China) for "medicinal" purposes demonstrates a mind-set that is not easy to change. And finally, Three: humans have formed their own in-groups and out-groups since our evolution. We've fought over territory, resources, and ideology. Our efforts would likely be more successful if we could stand in solidarity behind policies and rules meant to mitigate our effect on extinction rates, but because there are so many countries with different goals, it is extremely difficult in some cases to be successful in any efforts we might have.
In answering this I would define defaunation as an overall decrease of biomass and biodiversity, biomass being measured by the population numbers and biodiversity by species number. these papers in my opinion really addressed the impacts that humans have in the 6th mass extinction. humans have definitely accelerated the loss of species and caused many species to go extinct. I would have to say from a personal opinion that humans have definitely harmed the wildlife population with excessive hunting, hunting for sport, removal of pests and so on to the point in which we as humans have accelerated Earth's natural order of things . I think the only way that we can slow this 6th mass extinction from being worse than the last five is to get a global cooperative effort in rectifying the problem us humans have created. thus, being the tragedy of the commons.
ReplyDeleteThis is because the phenomenon occurs due to the synergistic effects of multiple causes and cannot truly be traced to one event. I would define this term broadly as the disappearance of a group of species from an environment.
ReplyDeleteLarge animals seem to have increased susceptibility to human destruction, as we know, because they provide large amounts of what humans need. Species within habitable areas to humans would be most affected by them, but those that inhabit extreme or inaccessible environments would be more protected from the human impact (except for global climate change). Species that humans can gain goods from, such as fur or wool or nutrients, would be at greater risk of being impacted by humans (sheep, pigs, cows).
I think habitat loss is the most important driver of defaunation because it happens rapidly and extensively, meaning species can hardly adapt or even migrate to new habitats. With climate change, there is at least time given for species to transition from generation to generation with gradual change.
Humans have only recently learned how to have a gentler impact on our environment and are only recently beginning to realize our power to alter the planet. With time, humans will become more aware of our impact and will gradually initiate change in order to preserve ourselves. Also, human population size has become gigantic, meaning changing our behavior will take a long time. The circumstances of living for humans varies greatly from region to region – not every human place on earth currently has the endemic ability to change in this way.
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ReplyDelete1) Why does the term defaunation remain a largely cryptic phenomenon? How would you define this term?
ReplyDeleteThe term remains so cryptic because of the lack of data there is to study not only species extinction, but other factors like species diversity, abundance, ranges, etc. I would define defaunation as the loss of species and population characteristics.
2) What makes certain lineages more susceptible to human impact (body size, geographic range, etc.)?
I think there’s a lot that can affect their susceptibility to human impact. Some of these can be migration patterns, nocturnal behavior, habitat, lifespan, etc.
2) Why do you think tropical, species-rich regions are seeing the largest population losses compared to other regions?
I think perhaps tropical regions are seeing the largest population losses because of their lifestyle characteristics. The tropics are seemingly regions of very specific conditions that allow life to exist. The extreme diversity has to be balanced and I think these regions are more susceptible to upset.