Ch. 20 mastering biology

gene flow is a concept best used to describe an exchange between

populations

according to the hardy weinberg theorem the frequencies of alleles in a population will remain constant if ___ if the only process that affects the gene pool

sexual reproduction

Male satin bowerbirds adorn structures that they build, called "bowers," with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them. The evolution of this male behavior is due to

sexual selection

women often have complications during labor while giving birth to very large babies whereas very small babies tend to be underdeveloped. which kind of selection is more likely at work regarding the birth weight of babies

stabilizing seleciton

Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?

stabilizing selection

most swiss starlings produce four to five eggs in each clutch. those producing fewer or more than this have reduced fitness. which of the following terms best describes this

stabilizing selection

which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations

natural selection

overtime the movement of people on earth has steadily increased. this has altered the course of human evolution by increasing

gene flow

the ease with which humans travel across the globe is likely to increase

gene flow

all the genes in a population are that population's

gene pool

modern travel along with migration reduces the probability of ____ having an effect on the evolution of humans

genetic drift

the DNA polymerases of all cellular organisms have proofreading capability. this capability tends to reduce the introduction of

genetic variation by mutations

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

founder effect

which of the following are basic components of the hardy weinberg model

frequencies of two alleles in a gene pool before and after many random matings

genetic drift is a process based on

the role of chance

which of these is a statement that darwin would have rejected

the smallest entity that can evolve is an individual organism

a mutation occurs when

there is a change in the DNA sequence of a gene

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Consequently, which statement about mules is true?

they have a relative evolutionary fitness of zero

the original source of all genetic variation is

mutation

in human gamete production there is an average of ___ crossover events per chromosome pair

2-3

if on average 46% of the loci in a species gene pool are heterozygous then the homozygosity of the species should be

54%

which of these individuals is a homozygous genotype

AA

what is the only evolutionary mechanism that consistently leads to adaptive evolution

natural selection

which of these is the smallest unit that natural selection can change

a populations gene frequency

if the frequency of a particular allele that is present in a small isolated population of alpine plants decreases due to a landslide that leaves an even smaller remnant of surviving plants bearing this allele then what has occurred

a bottleneck, genetic drift, and microevolution

a trend toward the decrease in the size of plants on the slopes of mountains as altitudes increases is an example of

a cline

rabbit ear size tends to decrease as latitude increases. this is an example of

a cline

every few years a giant axe chops off the head of every person who is over 6 feet tall. how will this affect the human population

alleles that promote tallness will decrease in frequency

which of these is the smallest unit upon which natural selection directly acts

an individuals phenotype

which definition of evolution would have been most foreign to charles darwin during his lifetime

change in gene fréquence in gene pools

in evolutionary terms, an organisms fitness is measured by its

contribution to the gene pool of the next generation

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to

cross your flies with flies from another lab

True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.

false

natural selection is most nearly the same as

differential reproductive success

Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?

directional selection

fossil evidence indicates that horses have gradually increases in size over geologic time. which of the following terms best describes this

directional selection

Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?

disruptive selection

which describes an african butterfly species that exists in two stinkingly different color patterns

disruptive selection

which type of selection tends to increase genetic variation

disruptive selection

natural selection changes allele frequencies in populations because some ____ survive and reproduce more successfully than others

individuals

how does diploidy help to preserve genetic variation

it allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes

which of the following statements best summarizes evolution as it is viewed today

it is the differential survival and reproduction of the most fit phenotypes

when we say that an individual organism has a greater fitness than another individual we specifically mean that the organism

leaves more viable offspring than others of its species

homologous pairs of chromosomes are lined up independently of other such pairs during

metaphase 1

generation to generation change in the allele frequencies in a population is

microevolution

what is the term for a change in the relative frequencies of alleles in a population form generation to generation

microevolution

which of the following evolutionary forces could create new genetic information in a population

mutation

crossing over resulting in an increase in genetic variation occurs between

non sister chromatids of homologous chromosomes

which of the following evolutionary forces consistently results in adaptive changes in allele frequencies

selection

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

stabilizing selection

which of the following statements is not a part of the hardy weinberg principle

the genotype frequencies in the offspring generation must add up to two

the evolutionary effects of genetic drift are greatest when

the population size is small