Chapter 23 The Evolution Of Population

1) Which of the following is the best modern definition of evolution? A) descent with modification B) change in the number of genes in a population over time C) survival of the fittest D) inheritance of acquired characters

Natural selection acts on individuals, but Example of this concept

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true? A) Each bird evolved a deeper, stronger beak as the drought persisted. B) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted. C) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation. D) The frequency of the strong-beak alleles increased in each bird as the drought persisted

Microevolution 3 mechanisms of this concept Only natural selection causes

prerequisite for evolution Mendel's work on pea plants provided

Genetic variation among individuals is caused by Phenotype is the product of Natural selection can only act on variation with Some phenotypic differences are determined by Other phenotypic differences are determined by

Genetic variation can be measured as For gene variability, average heterozygosity measures Nucleotide variability is measured by Nucleotide variation rarely results in Some phenotypic variation (does not, but rather from) Only genetically determined variation can have

Genetic variation _____. A) is created by the direct action of natural selection B) arises in response to changes in the environment C) must be present in a population before natural selection can act upon the population D) tends to be reduced by when diploid organisms produce gametes

New genes and alleles can arise by Sexual reproduction can result in genetic variation by A mutation is Only mutations in cells that A point mutation is

The effects of point mutations can vary (5)

Chromosomal mutations that (3) Duplication of small pieces of DNA Mutation rates are low in The average is about Mutation rates are often lower in ____________ and higher in _____________ Mutations accumulate quickly in

Sexual reproduction can In organisms that reproduce sexually, recombination of alleles is

population gene pool A locus is fixed if

Calculating Frequencies: For diploid organisms The total number of dominant alleles at a locus is By convention, if there are two alleles at a locus (examples of the math for frequencies on slide 37/38)

The Hardy-Weinberg equation describes If the observed genetic makeup of the population differs from expectations under Hardy-Weinberg, it suggests In a population where gametes contribute to the next generation randomly and Mendelian inheritance occurs, allele and genotype frequencies This poulation is said to be in

Hardy-Weinberg equilibrium describes the The Hardy-Weinberg theorem describes a In real populations, allele and genotype frequencies

The five conditions for nonevolving populations are rarely met in nature Natural populations can We can assume the locus that causes phenylketonuria (PKU) is in

In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because _____. A) the population is diploid B) heterozygotes can come about in two ways C) the population is doubling in number D) heterozygotes have two alleles

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg model? A) f(A1) = 0.9997, f(A2) = 0.0003 B) f(A1) = 0.9800, f(A2) = 0.0200 C) f(A1) = 0.9700, f(A2) = 0.0300 D) f(A1) = 0.9604, f(A2) = 0.0392

Three major factors alter allele frequencies and bring about most evolutionary change

Natural Selection: Differential success in reproduction results in For example, an allele that confers resistance to DDT in fruit flies increased in frequency after Natural selection can cause ___________ ________________ (define)

Genetic Drift: The smaller a sample, the greater the chance of Genetic drift describes how Genetic drift tends to reduce

The founder effect occurs when Allele frequencies in the small founder population can be The bottleneck effect is The resulting gene pool may no longer be reflective of If the population remains small

Genetic drift is significant Genetic drift can cause Genetic drift can lead Genetic drift can cause

Gene flow consists of Alleles can be transferred through Gene flow tends to Gene flow can decrease Example Gene flow can increase Example

Evolution by natural selection involves both New genetic variations arise by Beneficial alleles are Only natural selection consistently increases the Natural selection brings about adaptive evolution by

Relative Fitness: The phrases "struggle for existence" and "survival of the fittest" are misleading as they imply Relative fitness is the

Directional selection Disruptive selection Stabilizing selection Striking adaptations by natural

Natural selection increases Adaptive evolution occurs as Because the environment can change Genetic drift and gene flow do not consistently lead to adaptive evolution as they

Sexual selection is It can result in sexual dimorphism IntrAsexual selection is IntErsexual selection, often called mate choice, occurs when Male showiness due to mate choice can

The "good genes" hypothesis suggests Diploidy maintains genetic variation in the form of Balancing selection occurs when BS includes (2)

Heterozygote advantage occurs when Natural selection will tend to Heterozygote advantage can result from A mutation in an allele that codes for part of the hemoglobin protein causes

In frequency-dependent selection, the fitness of a phenotype Selection favors whichever phenotype is

Why Natural Selection Cannot Fashion Perfect Organisms: selection can evolution is adaptations are chance,

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population? A) population bottleneck and Hardy-Weinberg equilibrium B) heterozygote advantage and stabilizing selection C) mutation and natural selection D) founder effect and genetic drift

An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake? A) directional selection B) disruptive selection C) a founder event D) a genetic bottleneck

Which of the following is the most predictable outcome of increased gene flow between two populations? A) lower average fitness in both populations B) higher average fitness in both populations C) increased genetic difference between the two populations D) decreased genetic difference between the two populations

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing _____. A) nonrandom mating B) geographic isolation C) genetic drift D) gene flow

Currently the only predators of Galápagos marine iguanas are Galápagos hawks. Iguana body size is not correlated with risk of hawk predation, although small iguanas can sprint faster than large iguanas. If predators (for example, cats) that preferably catch and eat slower iguanas are introduced to the island, iguana body size is likely to _____ in the absence of other factors; the iguanas would then be under _____ selection. A) increase; directional B) increase; disruptive C) decrease; directional D) decrease; disruptive