Exam 27: Phylogenies and the History of Life

Some beetles and flies have antler-like structures on their heads,much like male deer do.The existence of antlers in beetle,fly,and deer species with strong male-male competition is an example of

You have obtained the following data on genetic similarity among five species.The higher the number,the closer the relationship between the two species (so a species is related to itself 100%).What approach can you take to construct a phylogeny using these data?

Figure 27.8 -The graphs above show percentage of change in three different molecular sequences plotted against time.Which of these molecular sequences would make a good candidate for a molecular clock?

You know that a particular stretch of DNA changes at the rate of 1 base per 10 million years.You sequence this length of DNA in two species and find that they differ by 4 bases: AATGCGATCG and AATGTTATGC.Based on these data,how long has it been since these two species diverged? (Hint: Ancestral sequence is AATGCTATGG.)

Which of the following is an example of homoplasy?

Which listing of geological periods is in the correct order,from oldest to most recent?

Figure 27.9 -What does the circled part of the phylogenetic tree above indicate?

Which of the following are typically responsible for island extinctions?

To use a genetic sequence as a molecular clock,the changes in nucleotides in the sequence must have accumulated at a steady pace over time.Drawing on what you know about codons and redundancy in the genetic code,which type of change would most likely be the type that is useful for a molecular clock?

Why would gene duplication events,such as those seen in the Hox gene complex,set the stage for adaptive radiation?

Figure 27.7 -For the streamlined bodies shown in Figure 27.7 above to be homologous instead of homoplasious,which of the following groups would also have to have streamlined bodies?

How do mass extinctions differ from background extinctions?

What is thought to be the significance of the duplication of homeotic genes?

You are using a molecular clock to investigate how long ago two taxa diverged.In the sequence of mitochondrial DNA you are using,in one location an arginine mutated to a thymine;thousands of years later,it mutated from thymine back to arginine.What effect will this reversion to arginine have on your estimate of the time of divergence?

Which of the following would be least likely in the fossil record?

Which of the following statements best describes the rationale for applying the principle of parsimony in constructing phylogenetic trees?

Islands are well known for having many endemic species-species that are unique to that location.What is a likely explanation for this pattern?

The theory of plate tectonics describes movement of plates of the Earth's crust through time.Which of the following can you deduce from what you learned in this chapter about plate tectonics?

Which of the following traits is useful in generating a phylogeny of species W,X,Y,and Z?

Dicynodonts were pig-sized reptiles that lived during the Permian geologic period.An increase in dicynodont species diversity occurred soon after the Permian extinction.Given what you know of this period,this increase in dicynodont species diversity represents ________,most likely due to ________.