Ap Bio Unit 7: Natural Selection

important terms and facts to know

Natural Selection

______ is the process by which organisms better adapted to their environment tend to survive and produce more offspring.

Evolution

_______ is the process by which species change over time through genetic variation and natural selection, leading to the development of new species.

What causes evolution?

Natural selection of more successful traits for any given environment

What does natural selection need?

Genetic variation is needed for natural selection to take place; variation makes survival more likely for a species

Mutation

Definition: A __________ is a permanent alteration in the DNA sequence that can result from errors in DNA replication, exposure to mutagens, or genetic recombination.

Genetic Drift

Genetic Drift is the random change in allele frequencies in a population, typically in small populations, leading to loss of genetic diversity.

Founder Effect

Founder Effect is a genetic phenomenon where a small group of individuals establishes a new population, leading to reduced genetic diversity. (portion of population gets separated)

Bottleneck Effect

The ___________ effect is a sharp reduction in the size of a population due to environmental events or human activities, leading to decreased genetic diversity and potential for inbreeding.

Gene flow

Organisms that migrate into or out of a population can add alleles to a population or remove alleles from the population

Hardy-Weinberg Equilibrium

• Describes a population in which allele frequencies remain constant

• Assumptions: no mutation, no migration, random mating, large population, no natural selection

• Equations: p^2 + 2pq + q^2 = 1 and p + q = 1

• Used to calculate genotype frequencies in a population

• Demonstrates how genetic variation is maintained in a population

phylogeny

Phylogeny is the evolutionary history and relationships among organisms, depicting their common ancestry through a tree-like diagram.

macroevolution

Macroevolution refers to large-scale evolutionary changes that occur over long periods of time, leading to the formation of new species.

speciation

Speciation is the process by which new species are formed through evolution, leading to the creation of distinct biological species.

Allopatric Speciation

Allopatric Speciation occurs when a population is divided by a physical barrier, leading to the formation of new species due to isolation and genetic divergence.

Sympatric Speciation

Evolution of new species in the same geographic area without physical separation. Can occur through ecological or behavioral changes.

Reproductive isolation

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences.

pre-zygotic isolation examples

Behavorial: Different mating rituals
Habitat: Mate in different ecological locations
Mechanical: Incompatible physically
Gametic: Two gametes unable to fuse

post-zygotic examples

Reduced-Hybrid Viability: hybrid is not healthy
Reduced-Hybrid Fertility: hybrid is not fertile

homologous structures

similar structures due to common ancestry

Vestigial structure

Structures that have no apparent function and appear to be residual parts from a past ancestor

Analogous Structure

structure with same function, but not due to common ancestry