Microevolution and Natural Selection

Natural selection

It increases genetic variation by introducing new alleles from other populations.

It reduces genetic variation by increasing the impact of genetic drift.

<p>They produce the genetic variation that makes evolution possible.</p> Signup and view all the answers

<p>It can lead to the loss of allelic variation and reduce the fitness of endangered populations.</p> Signup and view all the answers

<p>It explained how chance variations arise in a population and are precisely transmitted from parents to offspring.</p> Signup and view all the answers

<p>The population, not the individual, is the unit of evolution. It evolves because the combination of traits in each individual affects its survival and reproductive success, leading to changes in the population over time.</p> Signup and view all the answers

<p>The finch population evolved larger beaks because the surviving finches with larger, deeper beaks were able to crack the abundant large seeds during the food shortage, and thus were more likely to survive and reproduce. The underlying mechanism was natural selection.</p> Signup and view all the answers

<p>A severe bottleneck would likely lead to a loss of allelic variation and a reduction in genetic diversity, as the small population size would increase the effect of genetic drift and random chance on the population's gene pool.</p> Signup and view all the answers

<p>The introduction of new alleles would increase the genetic variation and diversity of the population, as it would provide new genetic material for natural selection to act upon and increase the population's adaptability to changing environments.</p> Signup and view all the answers

<p>Genetic drift can play a significant role in conservation biology by reducing the genetic diversity of small populations, making them more vulnerable to extinction. It can also lead to the loss of adaptive alleles, reducing the population's ability to adapt to changing environments.</p> Signup and view all the answers

<p>The loss of allelic variation can reduce the population's ability to adapt to changing environments, making it more vulnerable to extinction. It can also limit the population's ability to respond to natural selection, reducing its evolutionary potential.</p> Signup and view all the answers

<p>Mutations are rare.</p> Signup and view all the answers

<p>Nonrandom mating affects the frequencies of homozygous and heterozygous genotypes, but it does not affect allele frequencies in the gene pool.</p> Signup and view all the answers

<p>Natural selection alters allele frequencies through differential reproductive success, resulting in the transmission of alleles to the next generation in frequencies different from their relative frequencies in the present population.</p> Signup and view all the answers

<p>This process is called genetic drift, and it can lead to a loss of allelic variation in the isolated population.</p> Signup and view all the answers

<p>The influx of new alleles can increase genetic variation, and this process is called gene flow.</p> Signup and view all the answers

<p>The term for this process is genetic drift, and it is significant in conservation biology because it can lead to the loss of allelic variation in small or isolated populations.</p> Signup and view all the answers

<p>Natural selection affects the genetic variation of a population by altering the proportions of alleles passed to the next generation, leading to adaptation to the environment as individuals with advantageous traits are more likely to survive and reproduce.</p> Signup and view all the answers

<p>The founder effect, a type of genetic drift, occurs when a small group of individuals becomes isolated from a larger population, resulting in a new population with a gene pool composition that is not representative of the original population, leading to a loss of genetic variation.</p> Signup and view all the answers

<p>Gene flow, the transfer of alleles into or out of a population, reduces the genetic differences between populations and makes them more similar, increasing genetic variation.</p> Signup and view all the answers

<p>Intrasexual selection, a type of natural selection, leads to the adaptation of individuals with advantageous traits, resulting in increased genetic variation as those individuals are more likely to survive and reproduce.</p> Signup and view all the answers

<p>Heterozygote advantage, where heterozygotes have a selective advantage over homozygotes, maintains genetic variation in a population by allowing individuals to adapt to changing environments, leading to increased fitness.</p> Signup and view all the answers

<p>The bottleneck effect, a type of genetic drift, reduces the genetic variation of a population, leading to a loss of adaptive potential and decreased fitness.</p> Signup and view all the answers

<p>Natural selection acts on genetic variation through the differential reproduction of individuals with favorable traits, leading to an increase in the frequency of those traits in the population. This process results in adaptation to the environment as the population becomes better suited to its surroundings.</p> Signup and view all the answers

<p>Heterozygote advantage, where heterozygous individuals have a selective advantage over homozygous individuals, contributes to the maintenance of genetic variation by increasing the frequency of alleles that are beneficial in certain environments. This can lead to increased adaptation to changing environments, as populations with higher genetic variation are more likely to have individuals with traits that are beneficial in new environments.</p> Signup and view all the answers

<p>Intrasexual selection refers to the competition between individuals of the same sex for mates, while intersexual selection refers to the choice of one sex for mates with certain traits. Both types of selection can contribute to the evolution of populations by increasing the frequency of desirable traits and influencing the direction of evolutionary change.</p> Signup and view all the answers

<p>Genetic variation provides the raw material for adaptation to changing environments, as it allows for the selection of individuals with traits that are beneficial in new environments. Reduced genetic variation can limit the potential for adaptation, making populations more vulnerable to extinction in the face of environmental change.</p> Signup and view all the answers

<p>Natural selection and genetic drift are both mechanisms of evolutionary change, but they operate on different time scales and have different effects on population evolution. Natural selection acts on existing genetic variation, while genetic drift is a random process that can lead to the loss of genetic variation. The interaction between these two mechanisms can influence the direction and pace of evolutionary change.</p> Signup and view all the answers

<p>Microevolution refers to the evolutionary change that occurs within a population over a relatively short period of time. The key mechanisms that drive microevolutionary change are natural selection, genetic drift, and gene flow, which can lead to changes in allele frequencies and the adaptation of populations to their environments.</p> Signup and view all the answers

<p>Fitness refers to the ability to leave offspring and contribute to the gene pool, whereas relative fitness is the contribution an individual makes to the gene pool relative to the contributions of other individuals in the population.</p> Signup and view all the answers

<p>Stabilizing selection removes extreme variants and preserves intermediate types, while directional selection shifts the overall makeup of the population by favoring variants at one extreme of the distribution. Stabilizing selection maintains the status quo, whereas directional selection leads to a change in the population's characteristics.</p> Signup and view all the answers

<p>Intrasexual selection leads to the evolution of characteristics that enhance competitive ability, often resulting in sexual dimorphism, whereas intersexual selection drives the evolution of traits that increase attractiveness to the opposite sex. Intrasexual selection occurs within one sex, while intersexual selection involves both sexes.</p> Signup and view all the answers

<p>Heterozygote advantage occurs when individuals with two different alleles at a locus have a selective advantage over those with two identical alleles. This increases genetic variation and can lead to higher fitness in populations.</p> Signup and view all the answers

<p>Genetic drift is the random change in allele frequencies that occurs over time. It can lead to a loss of genetic variation, reducing the population's ability to adapt to changing environments and increasing the risk of extinction.</p> Signup and view all the answers

<p>Natural selection is the primary mechanism driving the adaptation of populations to their environments. It interacts with genetic drift, gene flow, and mutation to shape the evolution of populations, influencing the distribution of alleles and the traits they encode.</p> Signup and view all the answers