Grad Core- Week 4: more macroecology!
Thoughts on the papers for this week?
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Jason Lau
Defaunation & Biological Annihilation
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Graham 1986.
ReplyDeleteI am curious about how many generations it took for different species to disperse to their shifted ranges. I would imagine that larger species had larger home ranges which might have lead to fewer generations needed to establish the new species range compared to smaller species.
Sepkoski 1988.
This paper was very useful in finally understanding what is meant by alpha, beta, and gamma diversity. I have heard the terms before, but never really understood what they meant or how useful thinking about diversity in this way is. I thought that Figure 3 was very interesting in that there appeared to be less variation in diversity over time but more variation over different environments!
Alyssa, I also wonder if home range size and generation time are closely tied together?
ReplyDeleteWagner: This paper really ties in nicely to what we were talking about yesterday with the partitioning of the cube. The marine fauna had an innovation that allowed for more partitioning of the space.
I agree with Meghan that the Wagner paper tied in perfectly with the lecture yesterday. The figures clearly demonstrate the partitioning of space that allowed elevated diversity of ecological guilds.
ReplyDeleteI also found the Sepkoski paper interesting. I found the descriptions of the different types of diversity (alpha, beta, and gamma) particularly helpful.
Graham
ReplyDeleteI found this paper really interesting. I wonder if a species' ability to expand within its original nich/habitat slows speciation and the range expansion of its genus. Meaning that if a species is pushed out by competition does it evolve (faster) out of necessity and find new or expanded ranges?
Sepkoski 1988.
I found it interesting and not surprising that diversity seems to increase with increases in abiotic environmental variables that become available to species over time, rather than diversity simply increasing over time. This also supports the notion that speciation occurs as species find new ways to exploit the environment.
I also agree that the Wagner paper was a good summary of Tuesday's lecture.
It looks like we all agree: the Graham paper is totally cool and thought-provoking! I agree with the previous posts that there are lots of interesting details that can potentially be fleshed out, but the coolest thing about it to me is the simple yet important point that communities we see today are drastically different from those in the past. When I first realized this fact as an undergrad it blew me away. It took me until now to really put my finger on it though--communities are just as abstract as niches, neither is really definable until it already exists/is formed (in my opinion anyway, I know others may disagree). Way cool!
ReplyDeleteA Macroevolutionary perspective on species range limits
ReplyDeleteThis paper is an investigation of what in evolutionary history determines the range of species. This investigation points out three factors at play for contributing to range limitations; niches, spatial and dispersal variations in the environment. Patterns of distribution may be predicted by those of similar or related taxa. There are two areas of investigation for this paper, the relationship between the distributional limits of a clade and its age and species richness, and whether the distributional limits of species are conserved phylogenetically. The investigation of marine bivalve species found that older species are found more northerly, and there was no significance in the southern distributions. Species were found more rich in older clades. The problem with this sort of analysis is that sampling is always difficult and determining outside factors such as biotic are of the same suit. This analysis was also done for one taxa, this means that the findings in this paper may not be true across all.
Alpha Beta or Gamma: Where does all the diversity go?
ReplyDeleteAlpha Beta and Gamma describe types of diversity. The graph shows that the number of species decline with each of the five major extinctions. Time starts over every time allowing the populations to rediversify. This paper focuses on the varying levels of beta diversity in the Paleozoic. Analyses for this paper come from data gathered to reproduce Bambach’s rule, beta diversity is assessed for marine shelf fauna from the Paleozoic Era. The data shows that Alpha and Beta diversity were at play simultaneously during the Ordovician. This paper was so difficult for me to read because of the time periods and focus on ecological words I am not familiar with. I was happy that the summary was able to literally number the main points of conclusion.
Abundance Distributions Imply Elevated Complexity of Post-Paleozoic Marine Ecosystems
ReplyDeleteThis paper published in Science was seriously full of domain knowledge and statistical analyses. The RAD models were nothing I have ever seen before, great application but very new to me. Perhaps once I gain more exposure to analyzing data of this nature I will be more fit to understand this type of paper.