Topic 2: The Great American Biotic Interchange
The Great American Biotic Interchange (GABI) peaked around 3 Ma when the isthmus of Panama completely emerged and successfully joined the continents of North and South America. Species more easily migrated and attempted to colonize new territory. These papers discuss changes in the mammal populations on both continents, and how they were affected by changes in climate, competition and niche availability, among other factors. Here are some questions to ponder:
1. Why were North American species so much more successful in colonizing South America than South American species in colonizing North America?
2. What role did climate change play?
3. How does the MacArthur-Wilson Equilibrium theory apply?
4. How were native species affected?
5. How was body size affected?
6. How does adaptive radiation relate to the GABI?
7. How did proximity to the isthmus affect migration?
8. These papers discuss fauna, but what about flora? What about taxa other than mammals?
1. Why were North American species so much more successful in colonizing South America than South American species in colonizing North America?
2. What role did climate change play?
3. How does the MacArthur-Wilson Equilibrium theory apply?
4. How were native species affected?
5. How was body size affected?
6. How does adaptive radiation relate to the GABI?
7. How did proximity to the isthmus affect migration?
8. These papers discuss fauna, but what about flora? What about taxa other than mammals?
Cougar (Puma concolor)
ReplyDeleteThe cougar is a generalist predator. It is typically not an apex predator, competing with other predators over much of its range.
Its ancestral family (Felidae) originated in Asia about 11 Ma, and crossed the Berring land bridge between 8-8.5 Ma. The cougar invaded South America about 3 Ma as part of GABI and established over most of the continent. The North American population of cougar was believed to be killed off during the Pleistocene extinctions about 10 ka (Culver et al 2000), and since that time North America has been repolulated by South American cougar.
Adult males average 53-72 kg, while adult females average 34-48 kg. Sexual maturity is reached between 1.5-3 years of age. They typically average 1 litter of 1-6 kittens every 2-3 years with survival rates of just over 1 kitten/litter. Life expectancy is between 8-13 years.
Family: Felidae; Subfamily: Machairodontinae (Saber-Toothed Cats). This Subfamily includes the Genus "Megantereon, Smilodon, and Homotherium."
ReplyDeleteI'll post more info tomorrow afternoon.
llama (camelid ungulate)
ReplyDeleteLife span:About 20-25 years
Average Height:42-45" at the shoulder, 5.5 - 6' at the head
Average Weight:300-450 pounds
Average Gestation:350 days (11.5 months)
Babies:Average birth weight is 20-35 pounds. Babies are normally up and nursing within 90 minutes. They are weaned at about five to eight months.
Reproduction:Females are first bred at 18-24 months of age or older. Llamas do not have a heat cycle but are induced ovulators (ovulation occurs 24-36 hours after breeding). Thus they can be bred at any time of the year. Llamas reach full maturity at about age four. Reproductive rate: mean annual birth rate of 46%.
Growth Rate:growth occurs from the time they are born until about 3 years, slowing down after about 2 years; can grow up to 1 lb a day.
Migration: migrated into South America during the GABI.
Originating in the Central Plains of North America about 40 million years ago, the lama predecessors migrated to South America around 2.5 million years ago. The end of the Ice Age (10,000-12,000 years ago) marked the extinction of the camelid in North America. Llamas were domesticated from the guanacos of the Andean highlands of Peru about 5,000-6,000 years ago and are among the world's oldest domestic animals. Primarily a beast of burden, they provided native herdsmen with meat, wool for clothing, hide for shelter, manure pellets for fuel and sacrificial offerings to their gods.
(SOURCE: the South American Llama Association http://www.scla.us/llamafacts.html)
Numbers: Today there are an estimated 7 million llamas and alpacas in South America and over 100,000 llamas and 6,500-7,000 alpacas in the US and Canada.