Exam 24: Speciation

How are two different species most likely to evolve from one ancestral species?

Which of the following could be a vicariance event for species in that habitat?

A population of earthworms lives on an island in the middle of a river. Damming of the river causes flooding on the island, and only the highest points remain above water, creating several smaller islands with Now- separate earthworm populations on them. The earthworms cannot swim. Which of the following best describes this event?

Most causes of speciation are relatively slow, in that they may take many generations of organism to see changes, EXCEPT

House finches were found only in western North America until 1939, when a few individuals were released in New York City. These individuals established a breeding population and gradually expanded their range. The western population also expanded its range somewhat eastward, and the two populations have recently come in contact. If the two forms were unable to interbreed when their expanding ranges meet, what would this situation illustrate?

A researcher notices that in a certain moth species, some females prefer to feed and lay eggs on domesticated solanaceous plants like potatoes and tomatoes. Other females prefer to feed and lay eggs on wild solanaceous plants like Datura. Both male and female moths primarily use scent to find these plants from afar. Females tend to mate where they feed, and the researcher finds a genetic basis for scent preference in these moths. Based on the above information, what might be occurring in this moth species?

Which of the following evolutionary processes is not acting when two groups of organisms are identified as different species according to the Biological Species Concept?

Which of the following reproductive barriers would prevent a mating attempt?

Six potential species of seaside sparrows were genetically analyzed to determine their phylogenetic relationships. DNA analysis revealed that there were only two monophyletic groups with individuals from three subspecies making up each group. The three Atlantic coast subspecies formed one monophyletic group, while the three Gulf coast subspecies made up the other monophyletic group. If you could only save two subspecies of the seaside sparrows from extinction, would you choose two subspecies from the Atlantic coast, two from the Gulf coast, or one each from the Atlantic and Gulf coasts?

What keeps the two populations separate?

Natural selection for traits that keep distinct populations from reproducing with each other is called reinforcement. When is reinforcement beneficial?

Which of the following statements explains why animals are less likely than plants to speciate by polyploidy?

Which of the following is a disadvantage of the morphological species concept?

In hybrid zones where reinforcement is occurring, you should see a decline in

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysocelis is diploid, and Hyla versicolor is tetraploid. The frogs are identical in appearance, but their mating calls, which females use to find mates, differ. Which difference most likely evolved first?

Use the following information when answering the corresponding questions). About 3 million years ago, the Isthmus of Panama a narrow strip of land connecting North and South America) formed, divid marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sid isthmus. Based on the morphospecies concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629- 32.) -Which of the following describes the most likely order of events in speciation?

The peppered moth has a light and dark colour morph; the light morph was common in pre- industrial England. Increased pollution during the Industrial Revolution allowed dark morph moths to camouflage effectively against the dark, sooty background. Consequently, the dark morph became more common in industrial areas while the light morph remained common elsewhere. Recently, dark morph moths have been decreasing with reductions in pollution. Should the two morphs be considered separate species?

The snake family Typhlopidae consists of small, burrowing species with vestigial eyes. They are found in Australia, sub- Saharan Africa, India and some adjacent areas, and South America. What is the most likely explanation for this distribution?

Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came into contact?

A species of groundhog spreads through an environmentally varying region surrounding a lake; the different populations, each in their own environments, accumulate habitat- specific morphological traits. Which of the following is this an example of?