Exam 22: Speciation

Refer to the table. Certain populations of a copepod (a planktonic crustacean) may be reproductively isolated, even though females will mate with any male.Here, three females from one of the populations are placed with three males from another population.The diagonals represent crosses made between males and females of the same population.The numbers of offspring produced are listed in the table.In the crosses with reproductive isolation, what type of reproductive isolation exists?

Which mechanism can lead to selection against hybridization?

Which statement about hybrid zones is false?

Which example best illustrates temporal reproductive isolation?

Two species of three-spined stickleback fish have been found together in five different lakes.The larger bottom-dwelling species feeds on large prey close to shore.A surface-dwelling species feeds on small plankton in open water.DNA analysis shows that the two species in each lake are more closely related to each other than they are to any of the other species in the lakes.However, they are reproductively isolated.These two species are likely to have arisen due to

On the Galápagos Islands, some species of Darwin's finches have large bills capable of cracking hard nuts and seeds, some have smaller beaks useful for catching insects, and one has a beak capable of using tools to extract insects from within the bark of trees.In 1977, the Galápagos had abnormally low rainfall, and seed plants produced small crops.The population of seed-eating finches fell 85%.Large birds, especially males with strong beaks, survived disproportionately well because they were able to crack large seeds.This scenario suggests that rapid speciation in finches on the Galápagos Islands was facilitated by

Polyploidy can result in complete reproductive isolation in a minimum of _______ generation(s).

Divergent centric fusions can be barriers to reproduction in F1 hybrids because

The biological species concept means that species arise when

When differences in the shapes of reproductive organs between the males of one species and the females of the other lead to incompatibility, the species are said to be exhibiting _______ isolation.

Which is a key distinction between allopatric and non-polyploid sympatric speciation?

In the western United States, populations of an annual plant can be found almost continuously from San Diego to Seattle.Even though individuals from the San Diego and Seattle populations never come into contact, they can still be considered part of the same species under the ________ species concept because they can potentially interbreed.

Which factor or process does the Dobzhansky-Muller model of speciation necessarily require?

Molecular genetic analysis shows that a turtle hybrid zone contains mainly F₁ individuals with a few backcross individuals.What can you infer from this?

Which is not a prezygotic reproductive isolating barrier?

The genes F and G act in accordance with the Dobzhansky-Muller model leading to sterility in hybrids between two species of monkeyflowers.Any combination of the F1 and the G2 alleles causes hybrids to be sterile.Based on the Dobzhansky-Muller model, which genotype should have high fitness?

A hybrid zone between two species of butterflies contains individuals with widely varying genotypes, ranging from those matching both parental species to those with varying proportions of genes from the parental species.From this information one can infer that

Silene is a genus of plants in the Caryophyllaceae.Many species of this plant have separate male and female individuals.Two species meet at a hybrid zone.What change would most likely cause the hybrid zone to become wider?

Discuss the conditions on the Galápagos Islands that led to the evolution of the birds known as Darwin's finches.

Which type of reproductive isolating mechanisms would most likely arise from the coevolution of male and female reproductive organs in two sympatric populations of insects?