Ch. 14 The Origin of Species

Which of the following is an example of mechanical isolation? A sponge excretes eggs and sperm into the water, but only gametes from the same species will fertilize each other. Many insects have intricate "lock and key" mechanisms that prevent the male genitalia of one species from engaging with the female genitalia of a different species. A female moth produces a pheromone to which male moths of another species are indifferent. A mule, the offspring of a horse and a donkey, is sterile.

Many insects have intricate "lock and key" mechanisms that prevent the male genitalia of one species from engaging with the female genitalia of a different species.

polyploid speciation

Many plant species have formed by this; accidents in cell division result in extra sets of chromosomes.

A male snail and a female snail from different species attempt to mate, but the orientation of their different types of shells prevents mating from occurring.

Mechanical isolation

A biologist spends her summer break collecting frogs from a remote jungle in Peru. She discovers two distinct color forms that could be variants of a single species or two different species. What would be the most direct test of their species statusunder the biological species concept?

Observe mating in the natural environment of the two groups. If the two forms do not mate with each other, they are different species.

Polyploid

Organisms that possess more than two complete sets of chromosomes

Which of the following is an example of a prezygotic barrier? A hybrid fails to reach sexual maturity. A hybrid fails to develop beyond the first few embryonic stages. Pollen is regularly exchanged between flowers of two groups of plants, but a mutual incompatibility exists so that sperm do not fertilize eggs from the "wrong" group. A hybrid fails to produce functional gametes.

Pollen is regularly exchanged between flowers of two groups of plants, but a mutual incompatibility exists so that sperm do not fertilize eggs from the "wrong" group.

reproductive barriers

Both allopatric speciation and sympatric speciation depend on the establishment of this, which prevent(s) gene flow between a new species and its parent species.

The biological species concept

Defines a species as a group of populations whose members have the potential to interbreed with one another and produce fertile offspring

The birds-of-paradise are a group of brightly colored birds living mostly in New Guinea that have elaborate and elongated feathers. Behavioral isolation prevents different birds-of-paradise species from mating and reproducing. Which of the following describes a behavioral isolation reproductive barrier?

Males and females of one species live on one side of the island and never venture to the other side where other species live. Males of one species have shorter legs that only allow them to physically mate with females of the same species. Males and females of one species are only active at night, while other species are only active during the day. (THIS ONE) Males of one species perform orchestrated dances and sing songs that only attract females of the same species.

Population

A group of individuals of the same species that live in the same area and interact with one another

Which of the following statements about reinforcement is true? Reinforcement is a type of natural selection. Reinforcement decreases the morphological difference between two new species. Reinforcement is also called dispersive selection. Reinforcement increases the number of intermediate phenotypes.

Reinforcement is a type of natural selection.

In which of the following situations would speciation be most likely to occur? Seven monkeys escape from an enclosure. To everyone's surprise, they establish a small but viable population, coexisting successfully with humans in a partly suburban environment very different from their native African habitat. Bighorn sheep occupy mountains from Canada to Death Valley in Southern California, interbreeding all the way. The populations at the two ends of the range live in very different environments. A population of juniper shrubs is split in two by a canyon. Every year, strong winds carry a small amount of the shrubs' pollen across the canyon. A Japanese mollusk species whose larvae are often carried from port to port in ship bilge (waste) water now flourishes in San Francisco Bay, a busy commercial port.

Seven monkeys escape from an enclosure. To everyone's surprise, they establish a small but viable population, coexisting successfully with humans in a partly suburban environment very different from their native African habitat.

Two populations of flowers do not produce offspring because one blooms during early spring and the other blooms during late spring.

Temporal isolation

A subset of a population of birds leaves its habitat and colonizes a nearby island. After many generations, the island sinks and the population of birds living on the island returns to its original habitat. Which of the following statements mostaccurately describes the two bird populations? The populations will be able to interbreed even though they are different species. The populations were sympatric while they diverged. The populations will not be able to interbreed because they are different species. The birds were separated by dispersal.

The birds were separated by dispersal.

A group of ants escaped from a picnic basket carried to the top of a mountain and thrived in this area where there were no other ants. Many years later descendants of these ants crawled into a picnic basket on the mountain and traveled back to the valley from which their ancestors had come. Which of these observations would cause you to conclude that the ants on top of the mountain had become a different species from those in the valley?

The mountain ants could not mate with the valley ants.

speciation

The process that gives rise to new species

Which of the following is an example of a postzygotic reproductive barrier? One species of frog mates in April; another mates in May. Two fruit flies of different species produce viable but sterile offspring. The sperm of a marine worm penetrate eggs of the same species only. One species of flower grows in forested areas, another in meadows, and pollen is not transmitted between the areas.

Two fruit flies of different species produce viable but sterile offspring.

sympatric speciation

a new species may arise as mating and gene flow are reduced between populations that share the same area.

allopatric speciation

a population isolated by a geographic barrier becomes a new species as it accumulates changes by natural selection or genetic drift.

The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes ________ speciation.

allopatric

Two animals are considered members of different biological species if they _____.

are male and female, but cannot interbreed

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

behavioral isolation

Frequently, a group of related species will each have a unique courtship ritual that must be performed correctly for both partners to be willing to mate. Such a ritual constitutes a ________ ________ reproductive barrier.

behavioral; prezygotic

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

Microevolution

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

Gametic isolation

female and male gametes fail to unite in fertilization

Allopatric speciation is most likely to occur in which of the following scenarios? fleas in a doghouse and fleas in a veterinarian's office mountain lions in the canyons of Colorado and in the canyons of neighboring parts of Utah whales of the same species on opposite sides of the Atlantic ocean fish living in two different spring pools separated by a large expanse of desert

fish living in two different spring pools separated by a large expanse of desert

What is the first step in allopatric speciation?

geographic isolation (Formation of a reproductive barrier completes the process of speciation. In allopatric speciation, there must first be an event that physically separates populations of a species from each other. Allopatric speciation 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.)

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

habitat isolation

Under the biological species concept, a species is a group of organisms that

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

Temporal isolation

mating or fertilization occurs at different seasons or times of day

In _____ isolation, it is physically impossible for two species to mate with each other, often because their genitalia do not fit together properly.

mechanical

Adaptive radiation

occur(s) when a species gives rise to many new species after colonizing a region with diverse habitats.

Imagine that part of a population of flies is blown from the California coast to an offshore island. The island flies have no contact with the mainland flies for 10,000 years. Then an earthquake rearranges the landscape and the island is rejoined to the mainland. The former island flies can now mingle freely with the mainland flies. If attempts at mating between flies from the two groups are successful and the resulting offspring grow up strong and healthy and have offspring of their own, you could conclude that _____.

over the past 10,000 years, no speciation occurred in these flies

Sympatric speciation typically occurs through __________ and __________.

polyploidy in plants; habitat differentiation in animals

Habitat isolation

populations live in different habitats and do not meet

Two species that occasionally mate and produce zygotes, but that have incompatible genes that prevent the resulting embryo from developing, are affected by

reduced hybrid viability.

Speciation, or the formation of new species, is

responsible for the diversity of life.

Darwin thought that significant evolution was much too slow to be witnessed in a human lifetime. Recent experiments by biologists have _____.

shown that some populations can evolve quite rapidly, with important changes occurring over several generations in the laboratory

The process of speciation starts with a single species. It often involves the following steps: (1) two populations become physically separated from one another by a barrier to dispersal and stop exchanging genes; (2) the populations experience independent evolutionary changes; (3) changes in one or both populations result in development of reproductive isolating mechanisms that prevent interbreeding; further changes in geography may bring the groups back into contact. When do you officially have two separate species?

step 3

Mechanical isolation

structural differences prevent fertilization

Speciation without geographic isolation is called ________ speciation.

sympatric

Eastern and western spotted skunks breed at different times of the year. Therefore, they are prevented from interbreeding by _____ isolation.

temporal

Reproductive barrier

Anything that prevents successful interbreeding between species.

Which of the following examples uses the biological species concept to describe different species?

Female horses and male donkeys are able to mate, but their offspring (mules) are infertile.

Many populations of clams release their sperm and eggs into the same region of a lake, but only the sperm and eggs from the same species successfully unite to form zygotes.

Gametic isolation

Two populations of lobsters do not mate because one population lives in the Atlantic Ocean and the other lives in the Pacific Ocean.

Habitat isolation