Exam 22: Speciation

The wheat that we commonly eat is hexaploid, derived from a cross between two distinct species, one a diploid and one a tetraploid.The diploid wheat has 14 chromosomes.How many chromosomes does the hexaploid wheat have?

The different finch species in the phylogeny shown in the 22.8 of the textbook have all evolved on islands of the Galápagos archipelago within the past 3 million years.Molecular clock analysis (see Chapter 23) has been used to determine the dates of the various speciation events in the phylogeny.Geological techniques for dating rock samples (see Chapter 24) have been used to determine the ages of the various Galápagos islands.The table shows the number of species of Darwin's finches and the number of islands that have existed in the archipelago at several times during the past 4 million years. Plot the number of species of Darwin's finches and the number of islands in the Galápagos archipelago (dependent variables) against time (independent variable). Are the data consistent with the hypothesis that isolation of populations on newly formed islands is related to speciation in this group of birds? Why or why not?

Which example best illustrates behavioral reproductive isolation?

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.The populations are exhibiting _______ zygotic isolation.

Which statement about Hawaiian silverswords is true?

Which condition is unlikely to lead to allopatric speciation?

Refer to the table. The table shows five lineages of flies and provides some information on the areas that they have colonized and other notes on their biology.Which of the following is most likely?

A field contains two related species of flowering plants.Species A has a diploid chromosome number of 10, and species B has a diploid chromosome number of 16.If a third species arises as a result of hybridization between A and B, how many chromosomes will it have?

Refer to the figure. Drosophila species that have been crossed with each other allow evolutionary biologists to make general inferences about their evolution.The figure shows the relationship between prezygotic reproductive isolation and genetic distance for both allopatric and sympatric pairs.What is the likely explanation for the patterns observed in the graph?

Silverswords had no tree and shrub competitors prior to recent human ecological disturbance to the Hawaiian Islands.Descended from a tarweed ancestor that evolved in an environment with many tree and shrub species, its arrival on the islands represented a(n) _______because of a(n)_______.

For which reason would we expect rapid speciation to occur among animals with complex, sexually selected behavior patterns?

Which of the following is a major limitation of the morphological species concept?

Two closely related beetles are in the same location.They exhibit reproductive isolation, and they are both diploid.Biologists are arguing about which is more likely, that they evolved via sympatric or allopatric speciation.What statement presents the best argument?

Two populations of snails are allopatric, living in areas that have different soil compositions.The snails are not very mobile.Researchers are interested in whether the populations have acquired different types of reproductive isolation.Which would best determine if they are undergoing have mechanical isolation?

Two populations of annelids (worms) live in distinct areas and on different soil types.Researchers are interested as to whether the populations have acquired different types of reproductive isolation.Which method would be best to determine whether two populations exhibited temporal isolation?

One major category of reproductive isolating barriers, known as _______ isolating mechanisms, operates before fertilization.

A tetraploid fish is generated by autopolyploidy.Its haploid number is 35.It should thus have _______ chromosomes.

Which event would likely lead to an increase in speciation rate?

Which of the following scenarios is not an example of mechanical reproductive isolation?

An African genus of plant has large flowers pollinated by wind.In the neotropics, the same genus has a much larger number of species, with pollination occurring by orchid bees and many different species of hummingbirds.In both regions, the plants have hermaphroditic flowers.This may be an example of how _______ can lead to rapid speciation.