Evolution and Natural Selection Concepts

These flashcards cover key concepts regarding evolution, natural selection, and speciation as discussed in the lecture.

Evolution

Any change in the heritable traits of a population over time (successive generations).

Malthus' Theory

If the human population grew unchecked, there wouldn’t be enough living space and food for everyone.

Continental Drift Theory

Proposed by Alfred Wegener, explaining how organisms in different areas have common ancestry.

Lamarck's Theory

Changes acquired in an organism’s lifetime are passed onto the offspring.

Natural Selection

The process by which species change over time, known as survival of the fittest.

Descent of Modification

Darwin's proposal that each species has descended with changes from other species over time.

Fitness

The ability of an individual to survive and reproduce.

Stabilizing Selection

Natural selection that favors the middle state of variation.

Directional Selection

Natural selection that favors one extreme of variation.

Disruptive Selection

Natural selection that favors both/multiple extremes of variation.

Extinction

The dying out of a species due to failure to adapt.

Gene Flow

Any movement of genes from one population to another.

Genetic Drift

Mechanisms of evolution that occur by chance rather than natural selection.

Bottleneck Effect

When the size of a population is severely reduced by events like a natural disaster.

Founder Effect

When a small subset of a population establishes a new colony, leading to different genotypes.

Biological Species Concept

Definition of a species as a group whose members can interbreed in nature and produce fertile offspring.

Reproductive Isolation

Prevents genetic flow between members of different species, maintaining isolation.

Prezygotic Barriers

Barriers that prevent a zygote from being formed.

Postzygotic Barriers

Barriers that prevent fertile and viable offspring.

Speciation

The process by which species splits into two or more species.

Gradualism

Differences gradually evolve as populations adapt.

Punctuated Equilibrium

Species split in spurts of relatively rapid change followed by long periods of stability.

Hardy-Weinberg Assumptions

Conditions required to maintain genetic equilibrium where allelic frequencies remain constant.