Exam 12: Processes of Evolution

A group of organisms sharing a derived trait is known as a ____.

When a physical barrier separates a population, leading to the evolution of new species on either side of the barrier, ____ has occurred.

A ____ is a structural modification that enables an individual to exploit their habitat more efficiently.

Many male birds will expend a great deal of energy building nests. Females will mate with the males who build the best nests. This is best described as an example of ____.

One hallmark of speciation is ____.

Natural selection in the cichlid fish species of Lake Victoria occurred via ____.

The use of phylogeny to determine evolutionary relationships has practical applications in ____.

Fatter sociable weaver birds spend more time foraging where they are vulnerable to predation, are more attractive to predators, and are less likely to escape an attack. Conversely, thin birds risk starvation. Therefore, sociable weaver of an intermediate weight have a selective advantage. This is an example of ____ selection.

Environmental pressures result in a(n)____ of adaptive alleles.

Overhunting of species, such as tigers, reduces their numbers and their genetic diversity. This is an example of _____.

All of the alleles in a population make up the ____.

Alligators more closely resemble lizards than birds; however, alligators and birds have four-chambered hearts, which lizards do not have. In this example, the four-chambered heart is a ____, which indicates that alligators are ____ related to birds than to lizards.

Natural selection drives changes in allele frequencies by influencing traits with a ____ basis.

The graphs below show the frequency of the b+ allele over twenty generations in two populations of heterozygous flour beetles (data for a population of ten individuals is shown in graph A; data for a population of one hundred individuals is shown in graph B). Why does the frequency of the b + allele increase in both populations?