Exam 22: Speciation

Females of the beetle species Tribolium castaneum can readily mate with T.freemani.If these females mate with males of both their own species and males of T.freemani, nearly all of their offspring are pure species T.castaneum, with very few hybrids.This occurs because the sperm of T.castaneum blocks the sperm of T.freemani within the reproductive tract of the T.castaneum female.This is an example of _______ isolation, which is a form of prezygotic isolation.

Speciation rates in plants are _______ in animal-pollinated plants than in wind-pollinated plants.

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 F2 and the G1 alleles causes hybrids to be sterile.Based on the Dobzhansky-Muller model, which genotype should have high fitness?

Populations of beetles from different localities in Europe are possible cryptic species.How would one determine whether they are cryptic species based on the biological species concept?

The sterile offspring (mules) produced by horses breeding with donkeys exemplify

What is the primary reason that there are so many species of land snails in the Hawaiian Islands?

In an area of Europe where the fire-bellied toad overlaps and breeds with the yellow-bellied toad, hybrid offspring exhibit abnormalities such as misshapen mouths, fused vertebrae, and reduced numbers of vertebrae.Hybrid survival is not zero, but low compared with purebred individuals.Nevertheless, hybridization between these species is believed to have occurred at this location for centuries.This scenario describes an example of

Which statement about Darwin's finches is true?

Hybridization between two species of diploid plants resulted in a tetraploid.One has a haploid number of 14 chromosomes and the other has a haploid number of 17 chromosomes.The resulting plant came about via _______ polyploidy.

Which statement about the Dobzhansky-Muller model of speciation is false?

Suppose that two populations that were once isolated come into contact.Which result would not be likely?

Which of the following is a postzygotic isolating mechanism?

Sexual dimorphism may be associated with a higher rate of speciation in some organisms because

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. Which cross shows reproductive isolation?

Two species of crickets have partially overlapping ranges, in which hybrids are never found.Individuals-whether taken from overlapping areas or from non-overlapping areas-will rarely mate in the lab, because the females reject the songs sung by males of the other species.Of the few hybrids that are produced in lab crosses, all have low viability.Based on the information given, which statement is true?

Darwin's finches are thought to have evolved as a result of allopatric speciation.This is mainly based on the observation that

What is the critical distinction between allopolyploidy and autopolyploidy?

Which statement about polyploidy is true?

The biological species concept does not apply to which group of organisms?

Which situation is least likely to lead to geographic isolation and allopatric speciation?