Questions for Lab 4
I highly recommend that you read Chapter 6 before attempting to answer these
questions. It is not necessary to look at supplementary material for these papers.
Frog Dispersal:
1. How has terrestrial breeding and direct development allowed these frogs to occupy
habitats that other frog species cannot?
2. Explain the two hypotheses (Mesozoic vs. Cenozoic) in terms of vicariance and
dispersal, for the origin of Central American and West Indian eleutherodactyline frogs.
3. Many scientists have said that oceanic dispersal is impossible or very rare for frogs
because they cannot survive exposure to sea water. Referring to Figure 4 as necessary,
explain how biogeographic barriers (land connections, sea level) have affected speciation
patterns in these frogs, and try to explain how this group of frogs might have overcome
the problem of oceanic dispersal.
4. What major group of eleutherodactyline frogs are missing from the current study, and
how do the authors suspect they are related to other eleutherodactylines? Would you
expect the missing group to be older or younger than the other groups, and why?
Hominid Biogeography:
1. In the introduction, the authors state that a phylogeny is a crucial initial step to
formulate a biogeographic hypothesis. Using your knowledge of phylogenies from
earlier in the semester, your book and an example from this paper, explain why.
2. Discuss some of the major limitations of this study with regard to the data used.
3. Why would it make sense for hominid dispersal to be consistent with other
mammalian dispersal patterns?
4. Explain how the phylogenetic trees and area cladograms identify East Africa as the
region where hominid speciation is concentrated.