Biology 101: Intro to Biology Ch 21. Evolutionary Principles & Natural Selection

Population Genetics

the study of the allelic, genetic, & phenotypic variation within a population

Evolution

a change in the genetics within a population over time

Theory of Acquired Characteristics

characteristics acquired by an organism during its lifetime can pass offspring

Heritability of Acquired Characteristics

Lamarckian inheritance

Darwinian Evolution

populations rather than individuals evolve

Natural Selection

• the agent which determines a differential reproduction rate

• represents environmental changes that result in a selective advantage for one or more genotypes

Principles of Darwinian Evolution

• populations, rather than individuals, evolve

• evolution is possible because genetic variation exists within a population

• individuals with different genotypes in the population reproduce at different rates

Which of the following statements does NOT represent the idea of heritability by acquired characteristics?

I. A body builder develops stronger muscles during the course of his life, so his son will be strong as well.

II. A cat that lost its tail will produce offspring with shorter tails.

III. Over time, a population of heavily striped zebras increased over those without as much striping, as the heavily striped ones had a competitive advantage over the zebras with fewer stripes, and were, therefore, better able to reproduce.

1. II

2. I and III

3. III

4. I and II

5. I

III

Which of the following is an example of natural selection?

I. Albino animals are rare in nature because they are easy for predators to find.

II. The fastest gazelle is least likely to be eaten by a lion.

III. The gorilla that is strong enough to become alpha male is the most likely to pass on his genes.

1. I and II

2. III

3. II and III

4. I, II and III

5. I and III

I, II and III

Which of the following is NOT a principle of Darwin's theory of evolution?

1. Individuals with different genotypes may pass on their traits at different rates to the next generation.

2. An individual can evolve.

3. Traits are heritable.

4. Some traits give an individual a better chance of surviving.

5. A population consists of individuals with different genotypes.

An individual can evolve.

The study of the genetic variation within a population is known as:

1. Lamarkian genetics

2. Natural selection

3. Population dynamics

4. Population genetics

Population genetics

_____ can be defined as a change in a characteristic within a population over time.

Lamarckian inheritance

Natural selection

Evolution

Creationism

Evolution

Hardy-Weinberg equilibrium

the frequencies of alleles & genotypes will stay the same through the generations as long as there are no evolutionary influences

Hardy-Weinberg equation

• p² + 2pq + q² = 1

• can predict what our allele frequencies would be in the absence of evolutionary pressure on our allele of interest

Evolutionary agent

any force that alters the genetic structure of a population

Mate choice

when one sex starts to prefer certain traits in their mate

Genetic trait

a random process that results in certain individuals and their alleles being lost from the population

Which of the following is NOT an evolutionary agent that would move a population out of Hardy-Weinberg equilibrium?

1. Genetic drift

2. Natural selection

3. Large population size

4. Mate choice

Large population size

Which of the following scenarios would qualify for Hardy-Weinberg equilibrium?

1. Any population that is subject to natural selection and displays mate choice

2. A large population with no significant evolutionary pressure on the gene of interest

3. A large population with significant migration and loss of alleles due to genetic drift

4. A small population where it is easy to track each individual genotype

A large population with no significant evolutionary pressure on the gene of interest

If a phenotype is favored by mate choice, you would expect the allele frequency for that phenotype to _____.

1. decrease

2. decrease then increase rapidly

3. stay at equilibrium

4. increase

increase

What is the Hardy-Weinberg equilibrium used to describe?

1. Every gene in every species living in a single ecosystem without migration

2. The allele frequencies for genes of interest in a large population not subject to evolutionary pressure

3. The frequency of phenotypes present in a species displaying significant mate choice

4. The predicted time until the next episode of genetic drift will disrupt a population

The allele frequencies for genes of interest in a large population not subject to evolutionary pressure

If a phenotype becomes unfavorable due to natural selection, you would expect the allele frequency for that phenotype to _____.

1. increase then decrease rapidly

2. stay at equilibrium

3. decrease

4. increase

decrease

Fitness

• a measurement of the ability of a trait to increase or decrease the relative contribution of offspring by an individual to the next generation

• a phenotype which improves the fitness of an individual will improve its viability relative to other individuals in the population

Adaptation

a trait that enhances the survival or reproductive success of an organism

Homologous Structure

a structure shared between different organisms which evolved from a common ancestor

Analogous Trait

a trait which may be similar in appearance or purpose but which evolved independently in the two organisms in question

Convergent Evolution

when selective pressure results in the independent evolution of similar traits in two or more different organisms

Which of the following is an example of convergent evolution?

1. Prehistoric mammals thrive after the extinction of the dinosaurs.

2. Whales and fish both develop the ability to swim in the ocean.

3. The bones in a human hand are similar to those in a dog's paw.

4. A spider develops a web that is better at catching insects.

5. Finches in the Galapagos develop specialized beaks.

Whales and fish both develop the ability to swim in the ocean.

Which of the following is an example of a homologous structure or trait?

I. Arm bones of a human and wings of a bird

II. Wing of a penguin and wing of a mosquito

III. Beak of a penguin and beak of a duck

1. I and II

2. II

3. II and III

4. I, II and III

5. I and III

I and III

Which of the following is an example of analogous structures or traits?

I. Leg bones of a human and leg bones of a penguin

II. Wing of a finch and wing of a mosquito

III. Beak of a penguin and beak of a duck

1. I, II and III

2. II

3. II and III

4. I and III

5. I and II

II

A scientist notices several birds in the same area that are similar in appearance with the exception of different beak lengths. She observes that one type of bird with a particularly long beak can pick bugs out of holes in the ground, while the birds with shorter beaks cannot. The longer beak is an example of

1. Homology

2. Convergent evolution

3. Analogy

4. Equilibrium

5. Adaptation

Adaptation

A new mutation allows a cheetah to run faster and hunt down more prey than its slower counterparts. This mutation increased the _____ of the cheetah.

1. Analogy

2. Fitness

3. Natural selection

4. Homology

5. Equilibrium

Fitness

Directional Selection

selection in which individuals with a trait at one end of a phenotypic spectrum are most fit

Disruptive Selection

selection in which individuals at either end of a phenotypic spectrum are most fit

Stabilizing Selection

selection in which individuals in the middle of a phenotypic spectrum are most fit

Heterozygous genotype

a case in which heterozygous genotype has a higher relative fitness than either homozygous genotype

Balanced Polymorphism

two alleles of a gene maintained in a population because heterozygotes are more fit than their homozygous counterparts

A scientist has observed animals in a particular habitat for some time. She notices that in a population of birds those with either short or long beaks can find more food than those with average sized beaks. Over time, she notices a higher proportion of birds in the population have either short or long beaks. She is observing:

1. Directional selection

2. Heterozygote advantage

3. Balanced polymorphism

4. Disruptive selection

Disruptive selection

Which of the following forces is LEAST likely to cause a new species to arise in a population?

1. Directional selection

2. Balanced polymorphism

3. Incomplete dominance

4. Stabilizing selection

Stabilizing selection

A scientist has observed animals in a particular habitat for some time. She notices that the slowest gazelles tend to fall victim to predators more frequently than faster ones. Over time, she notes that the gazelle herd on average runs faster. She is observing:

1. Directional selection

2. Disruptive selection

3. Heterozygote advantage

4. Balanced polymorphism

Directional selection

A situation in which two alleles of a gene are maintained in a population because heterozygotes are more fit than their homozygous counterparts is called:

1. Heterozygote advantage

2. Directional selection

3. Balanced polymorphism

4. Stabilizing selection

Balanced polymorphism

Some studies have shown that a single copy of the cystic fibrosis disease allele can confer resistance to tuberculosis to a person. This is an example of:

1. Stabilizing selection

2. Disruptive selection

3. Gene dominance

4. Heterozygote advantage

Heterozygote advantage

Species

an independent evolutionary unit of organisms

Speciation

the process by which an ancestral species splits into two or more new species

Allopatric Speciation

speciation that results when a population is separated by a physical barrier

Geographic Speciation

speciation that results when a population is separated by a physical barrier

Sympatric Speciation

speciation that occurs without physical separation of members of the population

Polyploidy

a characteristic of a cell or organism with more than two complete sets of chromosomes

Define speciation.

1. It is the process by which an independent evolutionary unit of organisms is forced into extinction.

2. It is the process by which an ancestral species splits into two or more new species.

3. It is the process by which two or more species converge to become one species.

4. It is the process by which the characteristics of a cell or organism become more prevalent within a group of organisms.

It is the process by which an ancestral species splits into two or more new species.

A population of lizards is split by an earthquake which leaves half of the population on an island and the other half on the tip of the peninsula. These lizards can't swim. What type of speciation will occur?

1. Sympatric speciation

2. Allopatric speciation

3. Peripatric speciation

4. Parapatric speciation

Allopatric speciation

Polyploidy has contributed to which of the following patterns of speciation?

1. Sympatric speciation in plants.

2. Allopatric speciation in animals.

3. Allopatric speciation in plants.

4. Sympatric speciation in animals.

Sympatric speciation in plants.

Identify the factor that is responsible for allopatric speciation and NOT for sympatric speciation.

1. Gene mutation

2. Mate choice

3. Physical barrier

4. Competition

Physical barrier

Which of the following statements about species is MOST accurate?

1. Animals which do mate with each other or could mate with each other given the opportunity are members of the same species.

2. Animals which become separated geographically become different species.

3. Animals which look different are classified as different species.

4. Plants which cannot mate with each other because they are located too far apart are different species.

Animals which do mate with each other or could mate with each other given the opportunity are members of the same species.

Zygote

the cell which forms when a sperm cell fertilizes an egg cell

Prezygotic Reproductive Barrier

a mechanism that prevents fertilization from occurring

Postzygotic Reproductive Barrier

a mechanism that reduces viability or reproductive capacity of hybrid off spring

Prezygotic Barriers

• Spatial isolation

• Temporal isolation

• Mechanical isolation

• Gametic isolation

• behavioral isolation

Spatial Isolation

species are reproductively isolated by location

Temporal Isolation

species are reproductive isolated by different mating seasons

Mechanical Isolation

species are reproductively isolated due to incompatible reproductive organs

Gametic Isolation

species are reproductively isolated because the sperm of one species cannot find, attach or fuse with the egg of the other species

Behavioral Isolation

species are reproductively isolated because individuals in one species reject individuals of another species as possible mates

One way to overcome behavioral isolation that prevents animals from reproducing might be to _____.

1. keep the animals away from each other at all times, to reinforce the behavior

2. use genetic engineering to create compatible DNA

3. give the animals treats when they come near each other, thereby training them to accept each other

4. let nature take its course

5. clone the animals and raise them in a laboratory

give the animals treats when they come near each other, thereby training them to accept each other

A zoo wants to assist two related endangered species with their reproduction and plans to directly implant the sperm into the female. Which type of isolation can NOT be overcome in this way?

1. Temporal isolation

2. Mechanical isolation

3. Behavioral isolation

4. Spatial isolation

5. Gametic isolation

Gametic isolation

Spatial isolation is the main reason why _____ do not mate.

1. Siberian and South China tigers

2. sharks and dolphins

3. wolves and house cats

4. sea urchins and sea horses

5. red pandas and giant pandas

Siberian and South China tigers

One species of sea urchin is able to mate with another, but fertilization is rarely successful. What is this an example of?

1. Mechanical isolation

2. Gametic isolation

3. Temporal isolation

4. Spatial isolation

5. Behavioral isolation

Gametic isolation

Two species of plants that do not cross-pollinate are an example of _____ isolation because they flower at different times of the year.

1. behavioral

2. gametic

3. mechanical isolation

4. spatial

5. temporal

temporal

Postzygotic Reproductive Barrier

a mechanism that reduces viability or reproductive capacity of hybrid offspring

Hybrid Zygote Abnormality

when hybrid zygotes fail to mature normally

Hybrid Infertility

hybrids are incapable of producing offspring

Species

an independent evolutionary unit of organisms

Low Hybrid Viability

the viability of hybrid offspring is lower that offspring in either population

A farmer mates a goat and a sheep together. However, he finds he cannot use this hybrid animal to produce any new hybrids. This is an example of _____.

1. mechanical isolation

2. hybrid infertility

3. low hybrid viability

4. hybrid zygote abnormality

5. gametic isolation

hybrid infertility

A scientist mates two different organisms. She observes no offspring. A closer inspection reveals that the hybrid embryo does not develop properly. This is an example of _____.

1. hybrid infertility

2. low hybrid viability

3. gametic isolation

4. mechanical isolation

5. hybrid zygote abnormality

hybrid zygote abnormality

A scientist mates a blue population of lizards with a red population of lizards. She observes that one out of ten hybrid offspring survive to adulthood compared to, roughly, eight out of ten blue or red lizards. This is an example of _____.

1. hybrid zygote abnormality

2. low hybrid viability

3. mechanical isolation

4. hybrid infertility

5. gametic isolation

low hybrid viability

Which of the following statements is true?

1. A prezygotic reproductive barrier reduces the reproductive capacity of hybrid offspring.

2. Both prezygotic and postzygotic mechanisms can influence the speciation of a population.

3. Low hybrid viability is a form of prezygotic isolation.

4. Gametic isolation is a postzygotic reproductive barrier.

5. If two organisms can produce a viable hybrid, the parental organisms are not different species.

Both prezygotic and postzygotic mechanisms can influence the speciation of a population.

Which of these is NOT TRUE of a postzygotic reproductive barrier?

1. It occurs after the zygote has formed

2. Postzygotic mechanisms include hybrid zygote abnormality, hybrid infertility, and low hybrid viability.

3. It can reduce the reproductive capacity of the hybrid offspring.

4. It can increase viability.

It can increase viability.