AP BIO: Introduction to Evolution Quiz

Evolution

Descent with modification (Darwin); change over time in genetic composition of a population

Evolutionary Fitness

Individuals with favorable adaptations survive and reproduce more, passing traits to future generations

Descent With Modification

Organisms descended from an ancestor that lived in the remote past

Adaptations

Traits that enhance survival and reproduction in specific environments

Alleles

Alternative forms of a gene that arise by mutation and occupy the same locus

Dominant

Gene variant that expresses its trait even with a different allele present

Recessive

Allele that expresses its trait only when two copies are inherited

Heterozygote

Individual with two different alleles of a particular gene

Homozygote

Individual with two identical alleles of a particular gene

Genotype

The genetic constitution of an individual

Phenotype

Physical expression of an individual’s genetic makeup

Population

Group of same species living and interbreeding in a geographic area

Population genetics

Study of how allele frequencies and genetic variation change over time in populations

Gene pool

Sum of all alleles within a freely interbreeding population

Fitness

Ability of an organism to survive and reproduce, passing its genes to the next generation

Natural selection vs. Artificial selection

Natural: environment favors traits; Artificial: humans breed for desired traits

Homologous structure

Feature with similar anatomy due to common ancestor, may serve different functions

Vestigial structure

Feature that has lost its original function through evolution

Analogous structure

Trait with similar function that evolved independently in different species

Homologous structures

Similar anatomy from common ancestors (e.g., forelimbs of mammals)

Embryonic homologies

Similar early development (e.g., vertebrate embryos with tails & pouches)

Vestigial organs

Structures with little or no use (e.g., flightless bird wings)

Molecular homologies

Similar DNA or amino acid sequences across species

Convergent Evolution

Distantly related species evolve to resemble each other

Analogous structures

Similar structures that evolved due to similar environments

Microevolution

Change in allele frequencies in a population over generations

Genetic Variation

Parents pass on discrete heritable units (genes) that retain identity in offspring

Population Genetics

Study of how populations change genetically over time

Population

Group of same species living in the same area, producing fertile offspring

Gene Pool

All alleles at all loci in all members of a population

Fixed allele

All members homozygous for same allele; reduces genetic diversity

Natural Selection

Differential reproductive success based on trait advantage

Genetic Drift

Random fluctuation of alleles; stronger in small populations; may fix harmful alleles

Founder Effect

Small group becomes isolated; allele frequencies differ from original population

Bottleneck Effect

Severe population size drop alters allele frequencies

Gene Flow

Population gains or loses alleles due to immigration or emigration

Directional Selection

Population shifts toward one extreme phenotype

Disrupted Selection

Population shifts toward both extreme phenotypes

Stabilizing Selection

Population shifts toward the intermediate phenotype

Diploidy

Two alleles inherited; recessives can be hidden in heterozygotes

Heterozygote advantage

Heterozygotes have higher survival (e.g., sickle cell trait)

Sexual dimorphism

Differences between sexes in size, color, or traits

Intrasexual selection

Competition within the same sex for mates

Intersexual selection

Mate choice by one sex for individuals of the other