Homework 9

Question 1

If an extinction results in the loss of the longest branch on a phylogeny, this also represents the greatest loss of phylogenetic history. In this example, the loss of the tuataras would be a loss of the longest branch in this phylogeny, and therefore a loss of the greatest phylogenetic history. Losing the two sister species of Serpentes snake, however, would be a loss of the shortest branch and therefore the least phylogenetic history.

Answer 1

Serpentes, Tuataras

Question 2

During an ice age about 18,000 years ago, temperatures were significantly colder than modem temperatures, both at low and high altitudes. These changes would have had direct and indirect effects on survival by changing the food chain, and hence the diet of megafauna. Human hunting seems to have played a role in these extinctions, as archeological remains suggest that human hunters in this period had superior weapons compared to their predecessors. Pleistocene megafauna were probably already on the decline as a result of environmental change, so the intense degree of human hunting may have caused the extinction of almost 100 genera

Answer 2

Hunting by humans, habitat fragmentation, and the ice age played a large role in this extinction