bio exam 4 ch 24

Mutant tetraploid plants _____.

are unable to interbreed with a diploid plant

allopatric speciation

may occur when populations are separated geographically

sympatry

populations that live close enough to interbreed

gene flow

prevents speciation in sympatric populations

gene flow

reduces the divergence of populations

example of vicariance

The Grand Canyon forms, separating two populations of squirrels on the North Rim and the South Rim.

gene flow between distinct gene pools

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

polyploidy

Most causes of speciation are relatively slow, in that they may take many generations to see changes, with the exception of _____.

hybridization

Most polyploid plants arise as a result of _____.

example of a vicariance event

The level of water in a lake recedes, creating two lakes where there used to be one.

sympatric speciation and allopolyploidy

The origin of a new plant species by hybridizing two existing species, coupled with accidents during cell division, is an example of _____.

This situation represents isolation by vicariance.

There is an island in the middle of a large river that houses a large population of ants. Damming of the river causes the island to flood and only the highest points of the island are now above water. The ants cannot swim, so are now in multiple isolated populations. Which of the following best describes this event?

biological species concept

concept that cannot be applied to asexual or fossil species

distinguishes a morphospecies

distinctive characteristics, such as size, shape, or coloration.

gene flow

does NOT tend to promote speciation

reinforcement

due to natural selection against interbreeding and production of hybrid offspring

The source of the two sets of chromosomes

key difference between autopolyploidy and allopolyploidy

dispersal and colonization

Which factors are often associated with speciation events in island-dwelling species, such as the Galápagos finches studied by Rosemary and Peter Grant?

hybrid sterility

Which mechanism of reproductive isolation causes postzygotic isolation?

genetic isolation, genetic drift, and divergence

Which of the following describes the most likely order of events in allopatric speciation?

genetic drift

A change in allele frequencies caused by random events

vicariance

A population is fragmented into isolated subpopulations.

tend to slow adaptation to the new food plants

A small number of birds arrive on an island from a neighboring larger island. This small population begins to adapt to the new food plants available on the island as selection favors those birds with larger beaks. About twice a year, one or two more birds from the neighboring island arrive. These new arrivals ________.

morphological species concept

Before the application of DNADNA sequencing to fossils, which species concept was most useful for distinguishing human fossils?

allopatric speciation

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 met, it would be an example of _____.

Nondisjunction event during mitosis

How can an allopolyploid plant become a biologically fit new species?

Calls would be more different in areas of sympatry.

Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of closely related tree frogs in South America. If reinforcement is occurring, what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?

behavioral isolation

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent?

species living in sympatry following allopatric speciation

Modern humans (Homo sapiens) and archaic humans called Neanderthals (H. neanderthalensis) shared a common ancestor in Africa but diverged in different geographic areas. When modern humans migrated out of Africa and dispersed around the world starting about 100,000 years ago, they overlapped with Neanderthals in Europe. This scenario is best described as

first step in allopatric speciation

Physical isolation of two populations

gametic isolation

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm nuclei) from one species are unable to germinate and make pollen tubes to bring the sperm nuclei to the female ovules (which contain egg cells) of the other species. These two juniper species are kept separate by ________.

habitat isolation

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

a behavioral reproductive isolating mechanism

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 in contact?

gene flow

What does the biological species concept use as the primary criterion for determining species boundaries?

Two diverged populations are capable of mating and producing viable and fertile offspring.

When the ranges of two different species meet, a stable "hybrid zone" occupied by hybrid individuals may form. How is this possible?

allopatric speciation by vicariance

Which process led to the formation of the species pairs of Pacific and Caribbean snapping shrimp?

Transient and resident killer whales differ in feeding culture but can mate and produce viable offspring in captivity.

Why are Northeast Pacific populations of transient and resident killer whales thought to represent different ecotypes rather than different species?

Plant gametes can be produced by meiosis from somatic cells that have undergone many rounds of mitosis.

Why is speciation by polyploidy more likely in plants than in animals?

fertilization

_____ is the process by which haploid gametes form a diploid zygote.

reinforcement

______________ is most likely to occur when hybrids have lower fitness than either parent population

monophyletic group

a ___________ consists of consists of an ancestral population, all of its descendants, and only those descendants

Reinforcement

a type of natural selection called disruptive selection, which favors extreme phenotypes over intermediate phenotypes.

hybrid zone

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

polypoid

more than two complete sets of chromosomes.