Chapter 18 evolution and the origin of species

which specific concept did Charles Darwin and Alfred Wallace independently discover?

natural selection

adaptive radiation

speciation when one species radiates out to form several other species

behavioral isolation

type of reproductive isolation that occurs when a specific behavior or lack of one prevents reproduction from taking place

hybrid zone

area where two closely related species continue to interact and reproduce, forming hybrids

what is an example of a phenotype?

1. a certain duck has a blue beak 2. most cheetahs live solitary lives

Which situations most likely is an example of convergent evolution?

1. squids and humans have eyes similar in structure 2. worms and snakes both move without legs 3. some bats and birds have wings that allow them to fly

which of the following situations will lead to natural selection?

1. the seeds of two plants land near each other and one grows larger than the other 2. 2 types of fish eat the same type of food, and one is better able to gather food then the other 3. male lions compete for the right to mate with females, with only one possible winner

Which situation would most likely lead to allopatric speciation? A. flood causes the formation of a new lake. B. A storm causes several large trees to fall down. C. A mutation causes a new trait to develop. D. An injury causes an organism to seek out a new food source.

A. flood causes the formation of a new lake.

Which term is used to describe the continued divergence of species based on the low fitness of hybrid offspring? A. reinforcement B. fusion C. stability D. punctuated equilibrium

A. reinforcement

What is the main difference between dispersal and vicariance? A. One leads to allopatric speciation, whereas the other leads to sympatric speciation. B. One involves the movement of the organism, and the other involves a change in the environment. C. One depends on a genetic mutation occurring, and the other does not. D. One involves closely related organisms, and the other involves only individuals of the same species.

B. One involves the movement of the organism, and the other involves a change in the environment.

Which of the following statements is false? A. Punctuated equilibrium is most likely to occur in a small population that experiences a rapid change in its environment. B. Punctuated equilibrium is most likely to occur in a large population that lives in a stable climate. C. Gradual speciation is most likely to occur in species that live in a stable climate. D. Gradual speciation and punctuated equilibrium both result in the evolution of new species.

B. Punctuated equilibrium is most likely to occur in a large population that lives in a stable climate.

hich variable increases the likelihood of allopatric speciation taking place more quickly? A. lower rate of mutation B. longer distance between divided groups C. increased instances of hybrid formation D. Bequivalent numbers of individuals in each population

B. increased instances of hybrid formation

What do both rate of speciation models have in common?

Both models continue to conform to the rules of natural selection, and the influences of gene flow, genetic drift, and mutation.

Which condition is the basis for a species to be reproductively isolated from other members? A. It does not share its habitat with related species. B. It does not exist out of a single habitat. C. It does not exchange genetic information with other species. D. It does not undergo evolutionary changes for a significant period of time.

C. It does not exchange genetic information with other species.

Which components of speciation would be least likely to be a part of punctuated equilibrium? A. a division of populations B. a change in environmental conditions C. ongoing gene flow among all individuals D. a large number of mutations taking place at once

C. ongoing gene flow among all individuals

What is the main difference between autopolyploid and allopolyploid? A. the number of chromosomes B. the functionality of the chromosomes C. the source of the extra chromosomes D. the number of mutations in the extra chromosomes

C. the source of the extra chromosomes

Which reproductive combination produces hybrids? A. when individuals of the same species in different geographical areas reproduce B. when any two individuals sharing the same habitat reproduce C. when members of closely related species reproduce D. when offspring of the same parents reproduce

C. when members of closely related species reproduce

Which situation is not an example of a prezygotic barrier? A. Two species of turtles breed at different times of the year. B. Two species of flowers attract different pollinators. C. Two species of birds display different mating dances. D. Two species of insects produce infertile offspring.

D. Two species of insects produce infertile offspring.

If two species eat a different diet but one of the food sources is eliminated and both species are forced to eat the same foods, what change in the hybrid zone is most likely to occur?

Fusion is most likely to occur because the two species will interact more and similar traits in food acquisition will be selected.

Describe a situation where hybrid reproduction would cause two species to fuse into one.

If the hybrid offspring are as fit or more fit than the parents, reproduction would likely continue between both species and the hybrids, eventually bringing all organisms under the umbrella of one species.

How does the scientific meaning of "theory" differ from the common vernacular meaning

In science, a theory is a thoroughly tested and verified set of explanations for a body of observations of nature. It is the strongest form of knowledge in science. In contrast, a theory in common vernacular can mean a guess or speculation about something, meaning that the knowledge implied by the theory is very weak.

Two species of fish had recently undergone sympatric speciation. The males of each species had a different coloring through which the females could identify and choose a partner from her own species. After some time, pollution made the lake so cloudy that it was hard for females to distinguish colors. What might take place in this situation?

It is likely the two species would start to reproduce with each other. Depending on the viability of their offspring, they may fuse back into one species.

Why do island chains provide ideal conditions for adaptive radiation to occur?

Organisms of one species can arrive to an island together and then disperse throughout the chain, each settling into different niches and exploiting different food resources to reduce competition.

Why can polyploidy individuals lead to speciation fairly quickly?

The formation of gametes with new n numbers can occur in one generation. After a couple of generations, enough of these new hybrids can form to reproduce together as a new species.

If a person scatters a handful of garden pea plant seeds in one area, how would natural selection work in this situation?

The plants that can best use the resources of the area, including competing with other individuals for those resources will produce more seeds themselves and those traits that allowed them to better use the resources will increase in the population of the next generation.

Explain why the statement that a monkey is more evolved than a mouse is incorrect.

The statement implies that there is a goal to evolution and that the monkey represents greater progress to that goal than the mouse. Both species are likely to be well adapted to their particular environments, which is the outcome of natural selection.

Why do scientists consider vestigial structures evidence for evolution?

Vestigial structures are considered evidence for evolution because most structures do not exist in an organism without serving some function either presently or in the past. A vestigial structure indicates a past form or function that has since changed, but the structure remains present because it had a function in the ancestor.

dispersal

allopatric speciation that occurs when a few members of a species move to a new geographical area

vicariance

allopatric speciation that occurs when something in the environment separates organisms of the same species into separate groups

aneuploidy

condition of a cell having an extra chromosome or missing a chromosome for its species

reinforcement

continue speciation divergence between two related species due to low fitness of hybrids

temporal isolation

differences in breeding schedules that can act as a form of prezygotic barrier leading to reproductive isolation

speciation

formation of a new species

variation

genetic differences among individuals in a population

species

group of populations that interbreed and produce fertile offspring

Adaptation

heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment

punctuated equilibrium

model for rapid speciation that can occur when an event causes a small portion of a population to be cut off from the rest of the population

gradual speciation model

model that shows how species diverge gradually over time in small steps

hybrid

offspring of two closely related individuals, not of the same species

homologous structures

parallel structures in diverse organisms that have a common ancestor

vestigial structure

physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor

allopolyploid

polyploidy formed between two related, but separate species

autopolyploid

polyploidy formed within a single species

gametic barrier

prezygotic barrier occurring when closely related individuals of different species mate, but differences in their gamete cells (eggs and sperm) prevent fertilization from taking place

divergent evolution

process by which groups of organisms evolve in diverse directions from a common point

convergent evolution

process by which groups of organisms independently evolve to similar forms

natural selection

reproduction of individuals with favorable genetic traits that survive environmental change because of those traits, leading to evolutionary change

postzygotic barrier

reproductive isolation mechanism that occurs after zygote formation

prezygotic barrier

reproductive isolation mechanism that occurs before zygote formation

habitat isolation

reproductive isolation resulting when populations of a species move or are moved to a new habitat, taking up residence in a place that no longer overlaps with the other populations of the same species

reproductive isolation

situation that occurs when a species is reproductively independent from other species; this may be brought about by behavior, location, or reproductive barriers

sympatric speciation

speciation that occurs in the same geographic space

allopatric speciation

speciation that occurs via geographic separation