Chapter 18 quiz

Which of these habitats is likely to harbor the most recently diverged species?

A1

The Panama Canal was completed in 1914, and its depth is about fifty feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?

A1 and B1

Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?

A5 and B5

Which pair of scientists below would probably have agreed with the process that is depicted by this tree?

Lamarck and Wallace

Currently, two extant elephant species (X and Y) are classified in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with species Z.

Currently, two of the living elephant species (X and Y) are placed in the genus Loxodonta and a third surviving species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?

Z on top, X and Y branches off a stem.

A hybrid zone is properly defined as _____.

an area where mating occurs between members of two closely related species, producing viable offspring

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species 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.)

greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

The greatest number of endemic species is expected in environments that are _____.

isolated and show little ecological diversity

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysoscelis 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?

polyploidy

Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?

sympatric speciation and polyploidy

Researchers discovered that a new strain of bacteria that cause tuberculosis (M. tuberculosis) taken from a dead patient has a point mutation in the rpoB gene that codes for part of the RNA polymerase enzyme. This mutant form of RNA polymerase does not function as well as the more common form of RNA polymerase. A commonly used antibiotic called rifampin does not affect the mutant rpoB bacteria.

very few M. tuberculosis in the standard nutrient cell cultures carry the rpoB gene mutation, but almost all of the M. tuberculosis in the cell cultures with rifampin carry the rpoB mutation