Biology exam 2- chapter 24

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

genetic isolation, genetic drift, divergence

Which of the following is the first step in allopatric speciation?

geographic isolation

Sympatric speciation

the appearance of a new species in the same area as the parent population

Hybrid zones provide an opportunity to investigate _____.

the evolution of reproductive isolation

Rank the following in order from most general to most specific. 1. gametic isolation 2. reproductive isolating mechanism 3. sperm-egg incompatibility in sea urchins 4. prezygotic isolating mechanism

2, 4, 1, 3

postzygotic barriers

Barriers that prevent the hybrid zygote from becoming a fertile adult.

What is the most important factor that holds a gene pool of a species together and prevents speciation?

gene flow

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

biological

genetic

relating to genes or heredity

What prevents speciation from occurring in sympatric populations?

gene flow

How long does it take new species to form on Earth?

The time required varies considerably.

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be

28

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

Which of the following factors would not contribute to allopatric speciation?

Gene flow between the two populations is extensive.

What happens to the hybrid zone when gene flow is established?

Hybrids cease to be formed.

Which of the following statements about meiosis is correct?

Meiosis produces cells that differ genetically from the parent cell.

Which statement describes unity within a species?

Members have the potential to interbreed in nature and produce viable, fertile offspring.

Which of these is an example of temporal isolation?

One species is nocturnal, and the other species is not

gametic isolation

Sperm of one species may not be able to fertilize eggs of another species

reduced hybrid fertility

Sterile hybrids due to uneven chromosome number.

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

sympatric speciation

The formation of new species in populations that live in the same geographic area. can occur in a single generation

habitat isolation

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

reduced hybrid viability

When the genes of different species interact and impair hybrid development.

what is a species

a set of organisms with a unique genetic history

How are two different species most likely to evolve from one ancestral species?

allopatrically, after the ancestral species has split into two populations

A hybrid zone is properly defined as _____.

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

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and ________.

an increasing number of viable, fertile hybrids is produced over the course of the next 100 generations

According to the biological species concept, for speciation to occur, ________.

at least one gene, affecting one reproductive barrier, must change

Which of the following has been shown to cause speciation most rapidly?

autopolyploidy

Speciation

can involve changes to a single gene

Two animals are considered members of different species if they _____

cannot mate and produce viable, fertile offspring

morphological

characterizes a species by body shape and other structural features

In hybrid zones where reinforcement is occurring, we should see a decline in _____.

gene flow between distinct gene pools

Macroevolution is

evolution above the species level

temporal isolation

form of reproductive isolation in which two populations reproduce or breed at different times

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

gene flow

Which postzygotic barriers prevent formation of hybrids beyond the first generations?

hybrid breakdown

Reinforcement is most likely to occur when ________.

hybrids have lower fitness than either parent population

Reinforcement

in operant conditioning, any event that strengthens the behavior it follows

According to the punctuated equilibria model,

most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.

biological

perspective that stresses links between biology and behavior

How can reproductive barriers form sympatric populations while their members remain in the same geographic area?

polyploidy

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

polyploidy

According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods.

punctuated equilibrium

ecological

relating to or concerned with the relation of living organisms to one another and to their physical surroundings.

The difference between geographic isolation and habitat differentiation (isolation) is the ________.

relative location of two populations as speciation occurs

If biological species are defined in terms of reproductive compatibility, the formation of a new species hinges on ________

reproductive isolation

According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that ________.

speciation occurred rapidly in geologic time

The largest unit within which gene flow can readily occur is a

species

How do hybrid zones slow reproductive isolation?

species with incomplete mating barriers

Which term is used to describe populations that live close enough to interbreed?

sympatry

Fusion

the process or result of joining two or more things together to form a single entity.

How is length of time for speciation estimated?

time that elapses when populations of a newly formed species diverge

Which of the following statements describes mechanical isolation prezygotic barrier?

two snails have shells that spiral in different directions