Evolution: Key Concepts

• Evolution is the process where living organisms develop and diversify from earlier forms throughout Earth's history.

Acquired Characteristics

• These are modifications or changes in an organism's organs or tissues during its lifetime, due to use, disuse, or environmental effects, and are not inherited.

Artificial Selection

• This is selective breeding where humans intentionally select specific traits in plants and animals, breeding organisms with those desired traits to accelerate their evolution.

Variation

• Denotes a change or difference in condition, amount, or level, usually within certain limits.

Adaptation

• Adaptation is the process where an organism or species changes to become better suited to its environment, increasing its chances of survival and reproduction.

Biogeography

• Biogeography studies the geographical distribution of plants and animals.

Gene Pool

• Gene pool refers to the stock of different genes in an interbreeding population.

Genetic Drift

• The random fluctuation of allele frequencies within a population's gene pool is called genetic drift.
• It leads to changes in genetic makeup over time, particularly in smaller populations.

Bottleneck Effect

• A significant reduction in a population's size leads to a loss of genetic diversity and potentially skewed genetic representation within the surviving population.

Founder Effect

• Founder effect is the reduced genetic diversity when a population descends from a small number of colonizing ancestors.

Gene Flow

• Gene flow involves the transfer of genetic variation (alleles) from one population to another through the movement of individuals or their reproductive cells.

Speciation

• Speciation defines the formation of new and distinct species during evolution.

Reproductive Isolation

• Reproductive isolation refers to the mechanisms preventing two or more populations of organisms from interbreeding and producing fertile offspring.

Hybrids

• Hybrids are the offspring of two plants or animals of different species or varieties.

Biological Species Concept

• Defines a species as groups of populations that can interbreed and produce viable, fertile offspring, and are reproductively isolated from other such groups.

Allopatric Speciation

• Allopatric speciation occurs when a population of a species becomes geographically isolated, leading to the evolution of new species due to the lack of gene flow between the isolated populations.

Sympatric Speciation

• Sympatric speciation describes the evolution of new species from a single ancestral species while both continue to inhabit the same geographic region, without any physical barriers or geographic isolation.

Phylogenesis

• Phylogenesis refers to the evolutionary development and diversification of a species or group of organisms, or of a particular feature of an organism.

Phylogenetic Trees

• Phylogenetic trees are diagrams that visually represent the evolutionary relationships and history among different species or groups of organisms, based on shared ancestry.

Clade

• Clade is a group of organisms believed to have evolved from a common ancestor.

Node

• A node represents a branching point in a phylogenetic tree, symbolizing a common ancestor from which two or more lineages diverge.

Derived Characteristics

• Derived characteristics are traits that evolved in a common ancestor and are shared by its descendants, used to understand evolutionary relationships among species.

Charles Darwin

• Charles Darwin was a key figure in the development of evolutionary theory.

Genetic Variation

• Genetic variation: the diversity in DNA sequences within a population, leading to variations in traits

Gradualism vs. Punctuated Equilibrium

• Gradualism suggests evolution occurs through slow, continuous changes over long periods.
• Punctuated equilibrium proposes that evolution happens in bursts of rapid change punctuated by long periods of stability.

Prezygotic vs. Postzygotic

• Prezygotic barriers prevent fertilization from occurring between different species.
• Postzygotic barriers reduce the viability or reproductive capacity of hybrid offspring that do result from mating.