Bio Chapter 25 HW

A "one-snip test" is recommended to identify monophyletic groups−meaning that if you cut any branch on a tree, everything that "falls off" is a monophyletic group. Why is this valid?

One snip gets an ancestor and all of its descendants.

malaria is a tropical, mosquito-borne disease caused by a parasitic protist, Plasmodium. The species P. falciparum is particularly deadly, killing about 1 million people each year. There has been considerable debate over the origin of this species. Use this recent phylogenetic evidence to determine if P. falciparum originated from another strain of Plasmodium in humans, in chimpanzees, or in gorillas. Explain your reasoning.

P. falciparum originated from Plasmodium in gorillas because P. falciparum shares a most recent common ancestor with Plasmodium in gorillas.

Which is strong evidence supporting the impact hypothesis for the extinction of the dinosaurs? See Section 25.4 (Page) .

Extremely high quantities of iridium in rocks that formed around 65 million years ago Presence of an element abundant only in asteroids and meteorites supports the hypothesis that an asteroid impact occurred at the K-P boundary, around the time dinosaurs went extinct.

Which of the following statements about adaptive radiation is correct? Adaptive radiation occurs very slowly over time. Adaptive radiation occurs within a single lineage. Adaptive radiation occurs in the presence of competitors. Adaptive radiation occurs in species that live in one habitat.

Adaptive radiation occurs when a single lineage produces many descendant species.

Which statement about fossilization is correct? Organisms that live aboveground in dry areas are most likely to fossilize. Recent fossils are more common than ancient fossils because biodiversity has increased over evolutionary time. Rare, local, or ephemeral species leave a poor fossil record. Only hard parts of organisms can form fossils.

Rare, local, or ephemeral species leave a poor fossil record. Fossils are more likely to be found from species that have more abundant individuals, whether due to commonness, longevity of the species, or broad geographic range.

_____ is rapid speciation under conditions in which there is little competition.

adaptive radiation (Why: Adaptive radiation is rapid speciation under conditions in which there is little competition.

The different finch species found on the Galápagos Islands probably arose as a result of _____.

adaptive radiation (Why: The finches that initially immigrated to the Galapagos Islands experienced little competition, the result of which was the promotion of speciation.

Mass extinctions create conditions that promote _____.

adaptive radiation (Why: mass extinctions reduce competition and allow for periods of rapid speciation.)

The appearance of an evolutionary novelty promotes _____.

adaptive radiation (Why: the appearance of an evolutionary novelty may allow for the exploitation of previously unexploited niches.)

Which Anolis lizard ecomorph has long legs? Trunk/crown Crown Twig Trunk/ground

trunk/ground These ecomorphs need long legs to jump from one broad perch to another.

Which of the following would be LEAST likely in the fossil record? marine-dwelling species burrowing species desert-dwelling species marsh-dwelling species

desert-dwelling species

Feathers either play a role, or may have played a role, in _____.

extended hops, courtship, flight, and gliding.

True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection.

false The evolution of different ecomorphs is an example of disruptive selection. Each new ecomorph had characteristics that were ideal for a particular habitat, but as these characteristics developed, the lizards lost the ability to survive effectively in the other habitats on the island.

Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception. evolutionary innovation vacant ecological niches colonization of an isolated region that contains suitable habitat and few competitor species an adaptive radiation in a group of organisms (such as plants) that another group uses as food genetic drift

genetic drift

How can mass extinction events be distinguished from background extinctions?

A mass extinction occurs when at least 60 percent of species are wiped out within 1 million years. Note that this time frame makes our modern extinction rate unprecedented in the history of our planet.

Which organisms are not examples of an adaptive radiation? oneycreeper songbirds of the Hawaiian islands Anolis lizards of the Caribbean Mammals and reptiles in the post-dinosaur age Horses and deer in the post-dinosaur age

Mammals and reptiles in the post-dinosaur age Mammals and reptiles are not descended from a single lineage.

What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean?

Specific ecological niches Different species evolved in response to the selective pressures created by specific ecological niches on the islands.

Which statement is correct? Synapomorphies identify monophyletic clades. A synapomorphy may arise due to convergent evolution. A synapomorphy is an ancestral trait shared with an outgroup. Synapomorphies are examples of homoplasy.

Synapomorphies identify monophyletic clades.

Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true? A crown ecomorph living on one island is always the same species as a crown ecomorph living on a neighboring island. Twig ecomorphs can jump very well. The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place. The genetic relatedness of ecomorphs was determined by comparing their nuclear DNA sequences.

The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place. the historical evidence of adaptive radiation on an island is recorded in the evolutionary history of the ecomorphs currently living on the island.

How might this information be useful?

This information could possibly be used to understand how P. falciparum is so lethal.

True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics.

True Convergent evolution occurs when selective pressures produced by similar conditions (such as habitat) favor the evolution of similar solutions.