Drexel BIO 101/109 Midterm 1

Which of the following best explains why genetic bottlenecks and founder effects are evolutionarily important?

*Both result in small populations that are influenced more by genetic drift*

Most mammals don't drink milk after they are weaned because they lose the ability to digest lactose. This is true for about 60% of people. But most people of northern European descent can drink milk (areas where dairy farming is historically prevalent). What type of evolution would this exemplify?

*Directed selection*

What type of selection favors organisms with phenotypes that are at one extreme relative to the average phenotype?

*Directional*

Under the right conditions which type of selection is most likely to lead to the formation of new species?

*Disruptive*

In a situation in which males guard eggs and care for the young without help from the female, which of the following statements would most likely be correct?

*Females are more brightly colored than males and court males aggressively.*

The migration of reproductive individuals among populations results in a movement of alleles called?

*Gene Flow*

What can be concluded about comparing differences in molecular biology between different species?

*Genetic similarities and differences demonstrate species relatedness.*

Why do human taste preferences exist?

*Human feeding choices influence energy intake and, consequently, fitness.*

Assume that you carry an allele R, that causes you to help individuals to whom you are not related. This help increases their fitness and decreases yours. The frequency of allele R may still increase in the population:

*If individuals you help are likely to return the favor and help you at some point in the future*

Which of the following is the best way to distinguish male from female?

*Males produce motile gametes*

In a polyandrous mating system:

*Multiple males tend to mate with the same female*

Radioactive isotopes emit high energy particles that can damage DNA, These substances are known as?

*Mutagens*

Evolutionary change as a result of natural selection always leads to?

*None of the above are correct*

Kin selection is defined as:

*Selection for a behavior that lowers an individual's own chances of survival or reproduction, but raises those of a relative*

Natural selection decreases genetic variability in a population, this statement is:

*Sometimes correct, especially in cases of stabilizing selection*

If an individual could only help one person who would they help?

*Son with a flat tire*

Natural selection can only act on traits:

*That are heritable*

After 60 generations the average starvation resistance of fruit flies was 160 hours. What has happened to this population of fruit flies?

*They are genetically different from the original population*

If you find a species of fish in which males are much more brightly colored and larger than females, what might you infer about their mating system?

*They are polygynous.*

Artificial selection was used on corn to produce a single strain of corn with increased growth rates and greater resistance to a fungus. Although farmers have continued to select for these traits, the productivity of this strain is no longer increasing. This suggests that:

*all or most of the natural variation for these traits has been eliminated.*

A fossil is defined most broadly as:

*any preserved remnant or trace of an organism from the past.*

Polygynous species:

*are usually sexually dimorphic, with males*

All of the following conditions are necessary for reciprocal altruism to evolve in a species except:

*at least one of the sexes must not disperse so that some individuals always live near their kin.*

Gestational diabetes is thought to be the consequence of:

*conflict between the mother and fetus with respect to how much food the fetus should be given; the mother is equally related to the fetus and to any future offspring, while the fetus is not equally related to itself and any subsequent siblings.*

Convergent evolution can occur only when two species:

*evolve under similar selective forces*

In mammals, as well as many other species, males generally compete for females. The best explanation for this phenomenon is:

*females have a higher parental investment.*

Altruistic behavior in animals may be a result of kin selection, a theory maintaining that:

*genes promote the survival of copies of themselves when behaviors by animals possessing those genes assist other animals that share those genes.*

Because it is possible for a female to mate with multiple males, any of whom could be the father, male mammals and birds will always:

*have some degree of paternity uncertainty*

Behaviors that do not require environmental input for their development are called:

*instincts*

Maze-running behavior in rats:

*is a heritable trait.*

Evolution:

*is responsible for the increased occurrence of antibiotic-resistant bacteria.*

Adaptations shaped by natural selection:

*may be out of date, having been shaped in the past under conditions that differed from those in the present.*

In a species such as pigeons, in which males are almost indistinguishable in appearance from females, the most likely mating system is:

*monogamy*

The origin of all genetic variation is:

*mutation*

Evolution occurs:

*only via natural selection, genetic drift, migration, or mutation.*

Relative to birds, more mammalian species are:

*polygynous*

Mate guarding is a reproductive tactic that functions to:

*reduce paternity uncertainty.*

Genetic drift has the strongest effects in populations that are:

*small.*

Vampire bats

*sometimes regurgitate blood into the mouth of an unrelated bat that is close to starving.*

In a population in which a trait is exposed to stabilizing selection over time:

*the average value for the trait stays approximately the same, and the variation for the trait decreases.*

During gene flow, where do the genes flow to?

*the genes flow into and out of the population due to migration of individuals from one population to another.*

An animal will preferentially feed on:

*the prey that provides the most energy relative to effort*

A gene pool consists of:

*the total of alleles present in a population*

Predictions about sex related behavior

1) The sex that invests more will be more discriminating. 2) The sex that invests less will compete amongst themselves for access to the higher-investing sex.

The three simple conditions that are satisfied, evolution by naturalselection

1. There must be variation for the particular trait within a population. 2.That variation must be inheritable. 3.Individuals with one version of the trait must produce more offspring than those with a different version of the trait.

Why are Amish people more likely to have extra fingers and toes?

A group of individuals may leave a population and become the founding members of a new, isolated population

Founder Effect

A small number of individuals may leave a population and become the founding members of a new, isolated population

Communication

An action or signal on the part of one organism that alters the behavior of another organism

There are three important elements to an organisms fitness

An individual's fitness is measured relative to other genotypes or phenotypes in the population. Fitness depends on the specific environment in which the organism lives. Fitness depends on an organism's reproductive success compared to other organisms in the population.

Direct Fitness

An individual's total reproductive output

Fixed Action Patterns:

Are Triggered under certain conditions, require no learning, do not vary and once started, run to completion.

Polyandry

individual females mate with multiple males and is less common

Apparent altruism toward relatives can evolve through

kin selection

A pair bond appears:

monogamous

From an evolutionary perspective, behavior can best be viewed as:

part of the phenotype or a trait that can satisfy the three conditions required for evolution by natural selection

Behavior is part of an organisms

phenotype

In a polygamous mating system:

some individuals have multiple mates, while others have few or none;

If the environment changes

the alleles causing the traits favored by natural selection may change, too.

Factors that Prevent Populations from Progressing Inevitably toward Perfection

Environments change quickly. Variation is needed as the raw material of selection. There may be multiple different alleles for a trait, each causing an individual to have the same fitness.

Babies in the United States quickly and easily develop a fear of snakes. Yet they don't easily develop a fear of guns. Why?

Evolution can be slow in producing populations that are adapted to their environments.

Why do species have taste preferences

Feeding choices directly influence fitness. Living and reproducing require energy. Maximal extraction of energy and acquisition of essential nutrients Natural selection can shape feeding behavior.

Polygyny

Individual males mate with multiple females

Disruptive Selection

Individuals with extreme phenotypes experience the highest fitness, and those with intermediate phenotypes have the lowest.

Stabilizing Selection

Individuals with intermediate phenotypes are most fit.

Directional selection

Individuals with one extreme from the range of variation in the population have higher fitness; Pushing the average in one direction because one is allowed to reproduce more than the other

Reciprocal Altruism

Kindness toward unrelated individuals

Copulatory Plugs

Males block the passage of sperm into the females.

Sexual Monomorphism

Sexes are indistinguishable and means forms one

Which of these traits in rabbits do you think evolved due to interactions with predators?

Speed and Coat color

The important factor that distinguishes genetic drift from natural selection:

The change in allele frequencies is not related to the alleles' influence on reproductive success. The impact of genetic drift is much greater in small populations than in large populations.

Indirect fitness

The reproductive output brought about by altruistic behaviors toward close kin

Sexual Dimorphism

The sexes differ in size or appearance

Inclusive fitness

The sum of an individual's indirect and direct fitness

Population Bottleneck

The surviving members of a catastrophic event can have different allele frequencies than the source population and consequently the new population experiences evolution.

Fitness

a measure of the relative amount of reproduction of an individual with a particular phenotype, as compared with the reproductive output of individuals with alternative phenotypes

Genetic Drift is:

a random change in allele frequencies in a population

Why is it so much easier for an infant to learn a complex language than for a college student to learn biology?

a) Language involves memorization only, without the need for understanding rules, while biology involves both. b) Language is a feature with great evolutionary relevance for humans. c) Learning biology was not a behavior with evolutionary relevance for humans. d) Biology involves much more vocabulary than learning a complex language. *e) Both b) and c) are correct.*

Which of the following statements about mutations is incorrect?

a) Mutations are almost always random with respect to the needs of the organism. b) A mutation is any change in an organism's DNA. c) Most mutations are harmful or neutral to the organism in which they occur. d) The origin of genetic variation is mutation. *e) All of these statements are correct.*

Which of the following statements about marsupial mammals is correct?

a) They fill many niches in Australia that are occupied by placental mammals in other parts of the world. b) They are less fit than placental mammals. c) They have become extinct as a result of the greater fitness of placental mammals. d) They are more closely related to each other than they are to placental mammals. *e) Both a) and d) are correct.*

Altruistic Behaviors are:

behaviors that come at a cost to the individual doing the behavior while benefiting the recipient

Behavior is a:

combination of the genes and environment

Some behaviors are innate which are:

fixed action patterns

Which of the following statements about Charles Darwin is incorrect?

* He was enthusiastic about unleashing his theory of natural selection on the world as soon as he thought of it.*

Which one of the following statements best describes the difference between artificial and natural selection?

* Natural selection acts without the input of humans; artificial selection requires human input.*

The average time to death from starvation in a fruit fly is about 20 hours. Selecting for increased starvation resistance in fruit flies:

* can produce populations in which the average time to death from starvation is 160 hours.*

To establish that evolution by natural selection is operating in a population, one must demonstrate variability for a trait, heritability of that trait, differential reproductive success based on that trait, and:

* nothing else.*

While on the voyage of the HMS Beagle, Darwin:

* nurtured his love of studying nature, exploring plant and animal diversity, and collecting fossils.*

Evolutionary adaptation:

* refers both to the process by which populations become better matched to their environment and to the features of an organism that make it more fit than other individuals.*

When a group of individuals colonizes a new habitat, the event is likely to be an evolutionary event, because:

* small founding populations are rarely genetically representative of the initial population.*

Georges Cuvier's discovery of fossils of Irish elk and giant ground sloths:

* supports scientific evidence for extinction.*

"Survival of the fittest" may be a misleading phrase to describe the process of evolution by natural selection, because:

* survival matters less to natural selection than does reproductive success.*

About how much greater is the male reproductive output with three mates when compared to the female?

*2 times greater*

Which of the following is an example of a female mating with a male only after submitting him to a courtship ritual?

*A female bower bird will mate with a male only after inspecting the small thatched structure he has built for her.*

A population is:

*A group of individual of the same species that live in the same general location and have the potential to interbreed*

What is the difference between artificial selection and natural selection?

*Artificial selection requires human intervention, whereas natural selection does not require human intervention.*

In humans random mating is most likely to occur for which of the following characteristics?

*Artificial selection*

Prepared learning

Behaviors that are learned easily and by all (or nearly all) individuals

In Belding's ground squirrels, why are females much more likely than males to engage in altruistic behavior by sounding alarm calls?

Females tend to remain in the area where they were born, so the females that call are warning their own kin.

Which type of behavior is exemplified by the fact that a male bird will perform a complicated mating dance in the presence of a female of the same species?

Fixed action pattern

Differential Reproductive Success

From all the variation existing in a population, individuals with traits most suited to reproduction in their environment generally leave more offspring than individuals with other traits.