Exam 22: Descent with Modification: A Darwinian View of Life

The following questions refer to the evolutionary tree in Figure 22.2. The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Figure 22.2 -How many separate species, both extant and extinct, are depicted in this tree?

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

A high degree of endemism is most likely in environments that are

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1)Well-adapted individuals leave more offspring than do poorly adapted individuals. 2)A change occurs in the environment. 3)Genetic frequencies within the population change. 4)Poorly adapted individuals have decreased survivorship.

The following questions refer to the evolutionary tree in Figure 22.2. The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Figure 22.2 -According to this tree, what percent of the species seem to be extant (in other words, not extinct)?

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

Which of the following is not an observation or inference on which natural selection is based?

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Figure 22.1 -If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Figure 22.1 -Currently, two extant elephant species (X and Y)are placed in the genus Loxodonta and a third species (Z)is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?

About 13 different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the 13 species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). -According to a 1999 study, the vegetarian finch is genetically no more similar to the tree finches than it is to the ground finches, despite the fact that it is placed in the same genus as the tree finches. Based on this finding, it is reasonable to conclude that the vegetarian finch

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier's attempt to explain the existence of

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data?

About 13 different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the 13 species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). -If the six ground finch species have evolved most recently, then which of these is the most logical prediction?

Which of the following must exist in a population before natural selection can act upon that population?