Exam 15: Extinction and Evolutionary Trends

The figure below shows the increasing morphological complexity in crustacean legs in 12 different phylogenetic comparisons.Why did the authors of this study choose to analyze the data independently for each comparison?

Why are endemic species particularly endangered by global climate change?

The probability of extinction via predation is particularly high when

What kinds of evolutionary trends are represented by each of the two diagrams below? The x-axis represents an arbitrary scale for a trait value,in this case eyespot diameter on a butterfly's wing.

Which of the following scenarios may produce an active trend in evolutionary change? Briefly justify your answer. A.The mechanic stability of the exoskeleton of a group of terrestrial arthropods imposes an upper limit on the body size of these organisms.B.The evolution of an endoparasitic lifestyle results in overall smaller body size as parasite species diversify to utilize small-bodied hosts,which are more common than large bodied hosts.

While studying a group of ammonites (an extinct lineage of cephalopods)that lived during the Mesozoic,you measure the shell diameter of different fossil ammonite species.The table below represents the data you collected for each of six different time periods.What rule does the data conform to?

Describe how mean and variance of a trait value change in the absence of an evolutionary trend as a lineage diversifies.Use +,-,or = to indicate an increase,a decrease,or no change,respectively.You can use one,two,or all of the symbols to describe the possible changes in both mean and variance.Mean: Variance:

Which of the following observations would be expected if an infectious disease were a contributor to amphibian decline?

Where would you place the actual extinction date of a taxon if you knew that the Signor-Lipps effect was at work?

What effect of mass extinctions is described by the expression "dead clade walking"?

Extinction of a species means that

The earliest Homo sapiens fossils are about 200,000 years old.Could you use radiocarbon dating to determine the age of fossils from that period? Briefly justify your answer.

The graph below shows extinction rates during different periods of Earth's history.How many mass extinction events do scientists commonly infer from these data?

Which of the following is the greatest known mass extinction to date?

What is a sink population?

Data on extinction rates pre- and post-mass extinction rates suggest that the extinction rate remains elevated for some time after the mass extinction event.Which of the following statements is a plausible explanation for this observation?

The graph below shows the extinction rates for families of marine organisms over different periods of Earth's history.What is the best estimate for the background extinction rate given these data?

Approximately what percentage of marine species was lost during the Permian extinction?

Native plant A is endangered.You suspect that part of the reason for its decline is competition with an introduced exotic plant,B,that occupies a similar ecological niche.Which of the following experiments would help you decide whether competition with B contributes to the decline of A?

Elevated levels of iridium are found in the geologic layer at the K-T boundary.Is this unusual?