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Biology

Which of the following would a biologist describe as microevolution?

dramatic biological changes, such as the origin of flight, within a taxon

the extinction of species

the formation of new species

a change in the gene pool of a population from one generation to the next

A change in allele frequencies within the gene pool of a population

When a horse and a donkey mate, they produce infertile hybrids called mules. According to the _____ species concept, horses and donkeys are _____.

biological ... different species

Macroevolution can be defined as _____.

Macroevolution encompasses dramatic changes that take place over long periods of time.

The _____ species concept is the most applicable to classifying species from the fossil record?

morphological

Two species of clams inhabit the same marine habitat along the Atlantic coast. One releases gametes into the water in early spring, and the second species releases gametes into the water in late summer. Which type of reproductive barrier is at work between these species?

temporal isolation

Two rodent populations become separated when a large canyon develops in a previously unbroken forest. When is allopatric speciation between the two populations complete?

When the two populations evolve to be different enough so that they are incapable of interbreeding successfully when given the opportunity to do so under natural conditions, allopatric speciation is complete.

Which of the following types of reproductive barriers separates a pair of insect species that could interbreed except that one lives on goldenrod plants and the other on autumn daisies in the same general area?

habitat isolation

Which of the following types of reproductive barriers separates a pair of moth species that could interbreed except that the females' mating pheromones are not attractive to the males of the other species?

behavioral isolation

Which of the following types of reproductive barriers separates two species of sea cucumbers, whose sperm and eggs often bump into each other but do not cross-fertilize because of incompatible proteins on their surfaces?

gametic isolation

Two species interbreed occasionally and produce vigorous, fertile hybrids. When the hybrids breed with each other or with either parent species, however, the offspring are feeble or sterile. These species are separated by

reduced hybrid fertility

Which population would be most likely to undergo relatively rapid allopatric speciation?

A population of snakes becomes separated from other populations on a very large island that is formed by rising sea levels. Occasionally, a snake or two swims from the mainland to the island or from the island to the mainland.

A group of birds develops a unique set of mating preferences so that they are unlikely to mate with other birds of the same species in the same geographic area.

A population of flowering plants lives along the shore of a pond about one kilometer from the nearest neighboring population. Hummingbirds regularly fly back and forth across this distance and transport pollen between the two populations.

A group of wild horses is transported from Wyoming to a small desert island, previously without horses, off the coast of California. No additional horses reach the island thereafter.

A group of wild horses is transported from Wyoming to a small desert island, previously without horses, off the coast of California. No additional horses reach the island thereafter.

Uplift and formation of a mountain range divides a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of

allopatric speciation

Which type of organism is most likely to undergo sympatric speciation by polyploidy?

animal species with poor dispersal abilities whose populations exist in widely separated, small patches of habitat

animals, particularly those with highly selective females that select mates based on exaggerated traits

plant species that are capable of self-pollination and some degree of asexual reproduction

plant species that are incapable of asexual reproduction and do not self-pollinate

plant species that are capable of self-pollination and some degree of asexual reproduction

Two bird species overlap in a hybrid zone. They are isolated by a slight difference in the male songs and by the females' tendency to select males with the "correct" song. Hybrid offspring tend to have reduced fertility compared to either of the parent species. What effect might natural selection have in this situation?

Natural selection could lead to the stronger of the two species taking over and eliminating the other species.

Natural selection might favor males with less distinctive calls and/or females that are less "choosy."

Natural selection might favor males with more distinctive calls and/or females that are more "choosy." As a result, the reproductive barrier between the two species could be reinforced.

Natural selection could lead to the hybrid species taking over and eliminating the weaker parent species.

Natural selection might favor males with more distinctive calls and/or females that are more "choosy." As a result, the reproductive barrier between the two species could be reinforced

The ________ suggests that speciation occurs in brief spurts.

punctuated equilibrium model

One of the finest available sequences of fossils shows how horses have changed slowly and by subtle steps from small shrub-browsing ancestors to the large, grass-grazing modern horse. A large number of fossil species have been named, and it is often difficult to decide on the identity of a fossil horse because transitional forms are common. This record of evolution best fits the idea of

hybrid breakdown.

the gradual model of speciation.

punctuated equilibrium.

adaptive radiation.

the gradual model of speciation

Charles Darwin's main focus was on the gradual process of adaptation within populations. This form of change _____.

cannot account for increases in species diversity over time

________ increases when one or more new species branch off from a parent species that continues to exist.

Species diversity

The following options are all reproductive barriers. Which one is an example of a prezygotic barrier in which the two different species do mate?

Two dragonfly species regularly mate, but their gametes are incompatible.

Two crayfish species cannot interbreed because their genitalia do not engage properly with each other.

One bird species lives in wetlands, the other in dry forests; hence, they do not encounter each other.

Hybrid mules produced by mating donkeys and horses are sterile.

Two dragonfly species regularly mate, but their gametes are incompatible.

Often, the morphological species concept is used to define and describe species. Why?

This is the most convenient way of identifying species, and it is one of the few ways to identify fossil or asexual species.

Which of these is an example of temporal isolation?

One species is found only in North America, the other only in Europe.

The average weight of the individuals in one species is 100 pounds; in the other species the average is 640 pounds.

One species is diurnal (day active) and mates at high noon; the other is nocturnal (night active) and mates at midnight.

One species can't dance; the other does not respond to species that can't dance.

One species is diurnal (day active) and mates at high noon; the other is nocturnal (night active) and mates at midnight.

In _________, two species that breed during different times of the day or different seasons do not mix their gametes.

temporal isolation

What is the first step in allopatric speciation?

geographic isolation

___________ occurs when a population of organisms is geographically separated from other populations of the same species. Eventually, evolutionary change in one or both populations may produce reproductive barriers between them, which completes the speciation process.

Allopatric speciation

_____ generated many key crop plant species in the past, and continues to be an important method for plant geneticists today.

Sympatric speciation by polyploidy

_______ is often associated with polyploidy in plants. Polyploid plants tend to produce large fruits and flowers and other exaggerated traits, and thus are often valuable for human use.

Sympatric speciation

The evolution of numerous ecologically diverse species from a single ancestor in a relatively short time period, as seen in Darwin's finches, is called _____.

adaptive radiation

__________ occurs when ecological opportunities are great compared to the diversity of species present in a habitat. Under these conditions, a single species may rapidly diversify to produce a broad array of new, specialized species.

Adaptive radiation

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

punctuated equilibrium

Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill new or vacant ecological roles in their communities.

adaptive radiation

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

allopatric speciation

Definition of a species as a population or groups of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such populations.

biological species concept

A definition of species in terms of ecological roles (niches).

ecological species concept

A geographic region in which members of different species meet and mate, producing at least some hybrid offspring.

hybrid zone

A definition of species in terms of measurable anatomical criteria.

morphological species concept

A definition of species as the smallest group of individuals that shares a common ancestor and forms one branch on the tree of life.

phylogenetic species concept

An organism that has more than two complete sets of chromosomes as a result of an accident of cell division.

polyploidy

A reproductive barrier that prevents hybrid zygotes produced by two different species from developing into viable, fertile adults. Includes reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

postzygotic barrier

A reproductive barrier that impedes mating between species or hinders fertilization if mating between two species is attempted. Includes temporal, habitat, behavioral, mechanical, and gametic isolation.

prezygotic barrier

In the fossil record, long periods of apparent stasis in which a species undergoes little or no morphological change interrupted by relatively brief periods of sudden change.

punctuated equilibrium

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids.

reproductive isolation

The evolution of a new species.

speciation

The formation of new species in populations that live in the same geographic area.

sympatric speciation

The branch of biology that identifies, names, and classifies species.

taxonomy

A change in the gene pool of a population due to chance; effects of _________are most pronounced in small populations.

genetic drift

Genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the composition of the new population's gene pool is not reflective of that of the original population.

founder effect

Hybrid sterility, nybrid instability or weak hybrids are examples of ______.

Postzygotic barriers to reproduction

Temporal isolation, behavioral isolation and mechanical isolation are examples of _____.

Prezygotic barriers to reproduction

A reproductive isolating mechanism in which members of different species mate at different times of the year/ in different seasons.

Temporal isolation

A pre-zygotic isolating mechanism, which refers to mating rituals/behaviors that are distinct to particular species. Such behaviors identify members of the same species.

Behavioral isolation

a form of reproductive isolation that occurs because of an incompatibility in structure of the male and female sex organs.

mechanical isolation

_______ speciation has no geographical barrer.

sympatric

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