뒤로Evolution of Populations - General Biology
이 집합의 용어 (29)
Genetic variation refers to differences in DNA sequences among individuals in a population, which contribute to diversity in traits.
What are the main sources of genetic variation? HINT: There are 3.
Sources include mutations, gene flow, and sexual reproduction (crossing over, independent assortment).
Genotype is the genetic makeup of an organism; phenotype is the observable traits resulting from genotype and environment.
Mutations occur in DNA; only mutations in germ cells (sex cells) can be passed to offspring.
What is natural selection?
Natural selection is the process where individuals with advantageous traits survive and reproduce (fitness) more, changing allele frequencies over time.
Genetic drift is a random change in allele frequencies due to chance events, especially in small populations.
What is the founder effect?
The founder effect occurs when a small group starts a new population, causing reduced genetic variation and different allele frequencies. (Colonization)
The bottleneck effect is a sharp reduction in population size that reduces genetic diversity and alters allele frequencies.
What is gene flow?
Gene flow is the transfer of alleles between populations through migration, increasing genetic similarity.
How does natural selection influence phenotype frequencies? Name the types. HINT: There are 3.
Natural selection changes phenotype frequencies through directional, disruptive, and stabilizing selection.
What is directional selection?
Directional selection favors one extreme phenotype, shifting the population's trait distribution in one direction.
Disruptive selection favors both extreme phenotypes over intermediate ones, potentially leading to two distinct groups.
Stabilizing selection favors intermediate phenotypes and reduces variation by selecting against extremes.
How can natural selection change allele frequencies? Name the types. HINT: There are 3.
Natural selection changes allele frequencies through positive, negative, and balancing selection.
Positive selection increases the frequency of beneficial alleles in a population.
Negative selection removes harmful alleles, decreasing their frequency.
Balancing selection maintains multiple alleles in a population, preserving genetic diversity.
Frequency-dependent selection occurs when the fitness of a phenotype depends on its frequency relative to others in the population.
Natural selection favors traits for survival; sexual selection favors traits that increase mating success.
Intrasexual selection is competition within a sex; intersexual selection is mate choice by the opposite sex.
Costs include energy and risk; benefits include increased reproductive success by attracting mates or winning competition.
The sex that competes more (often males) is more influenced by sexual selection; the other sex is more influenced by natural selection.
What is needed for evolution and why?
Variation is needed for evolution because genetic differences among individuals are needed for allele frequencies to change.
What is a population?
A group of interbreeding individuals (species) living in the same area.
What is natural selection measured by? Define it.
Fitness is measured by how well individuals can survive and reproduce. (Revolves around traits)
How are most alleles formed?
Recombination: the reshuffling of alleles through meiosis, creating new combinations.
What has to occur to the H-W equation for evolution to occur?
There must be a change in the equation from generation to generation.
What can change the H-W equation. HINT: Many examples
Mutations
Assorted/Specific Mating: Not having an equal chance of getting a mate
Natural selection
Gene flow
Genetic Drift
What are the effects of Genetic Drift? HINT: 4 Key Points
Significant in Small Populations
Random change in allele frequencies
Loss of genetic variation within a population
Can cause harmful alleles to become permanent (leads to extinction)