Chapter 23-24 Mastering Biology

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T or F? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift, no gene flow, no mutation, random mating.

relative location of 2 populations as speciation occurs

The difference between geographic isolation and habitat differentiation is the....

population size is small

The evolutionary effects of genetic drift are greatest when the__________.

Evolution

This can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met. Descent with modification.

sympatry

Which term is used to describe populations that live close enough to interbreed?

gene flow

Workers from a nearby greenhouse accidentally introduce white flower seeds into this population's habitat.

Population B

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown. In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?

Population A

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown. Which population is most likely to be affected by the bottleneck effect?

gametic isolaiton

a coral's sperm can't fertilize another's eggs

species

a set of organisms with a unique genetic history.

biological

not applicable for extinct species

mutation

occurs when there is a change in the DNA sequence of a gene. Does little to change allele frequencies.

temporal isolation

one species is nocturnal and the other is not.

Morphological

relies on similarities in structure

genetic drift

responsible for the founder effect and the bottleneck effect. Causes allele freq. to fluctuate randomly. Based on the role of chance

morphological and phylogenetic

species acceptance criteria can be subjective. accommodates asexual reproduction

Disruptive selection

tends to increase genetic variation

sympatric speciation

the appearance of anew species in the same area as the parent population

macroevolution

the evolution above the species level.

gene flow

the migration of individuals gametes. Prevents speciation from occurring in sympatric populations.

Adaptive radiation

the rapid speciation under conditions in which there is little competition. Mass extinctions create conditions promote this.

morphological, phylogenetic, and biological

used by scientists in classification

genetic drift

A storm kills many plants at random.

sexual reproduction

According to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if _____ is the only process that affects the gene pool.

directional selection

If there is no gene flow, the curve shifts to the left or to the right, and the population size consequently increases over successive generations, which of the following is most likely occurring?

2-3

In human gamete production there is an average of _____ crossover events per chromosome pair.

heterozygotes can come about in 2 ways

In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because _____.

genetic variation

This must be present in a population before evolution can occur in the population

stabilizing selection

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation?

individuals

Natural selection changes allele frequencies because some _______ survive and reproduce more successfully than others.

natural selection

Plants with purple flowers attract more insects, which pollinate the plants.

stabilizing selection

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating

selection

Which of the following evolutionary forces results in adaptive changes in allele frequencies?

geographic isolation

Which of the following is the first step in allopatric speciation?

biological

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

cannot mate and produce viable, fertile offspring.

2 animals are considered members of different species if they________.

habitat isolation

2 fish species spawn a different depths

genetic drift

A person uproots the five closest plants, which all happen to have white flowers.

gene pool

All the genes in a population are that population's _____.

Freq. of 2 alleles in a gene pool before and after many random matings

Basic components of the Hardy-Weinberg model

nonsister chromatids of homologous chromosomes.

Crossing over, resulting in an increase in genetic variation, occurs between _____.

genetic isolation, genetic drift, divergence

Likely order of events in allopatric speciation

biological and phylogenetic

Dogs and gray wolves can interbreed. They have a high degree of genetic similarity but their anatomies are widely different. What is the 2 species concept?

natural selection

During an extreme heat wave, plants with white flowers survive better.

allopatrically

How are 2 different species most likely to evolve from one ancestral species?

varies

How long does it take new species to form on earth?

sympatric speciation and polyploidy

These have led to the origin of new species

mutation

The original source of all genetic variation is_________.

the post zygotic barrier called hybrid inviablitity

Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate?

value of a characteristic, size, color

What does the x-axis on a bell-shaped curve represent?

founder effect

What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population?

the allele freq. should not change

Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus, _____.

phylogenetic

based on evolutionary history

behavioral isolation

beetle mating displays show different insect pollinators

temporal isolation

birds are active during different times of day

stabilizing selection

causes no change in the average of the population

natural selection

consistently leads to adaptive evolution

Biological species

defined by reproductive isolation and are the model used for grouping extinct forms of life.

directional selection

drives the average of the population in one direction

mechanical isolation

flowers accommodate different insect pollinators

microevolution

generation-to-generation change in the allele frequencies in a population is_________.