Species Concepts and Reproductive Isolation

Biological Species Concept

Defines species by ability to produce viable, fertile offspring

Reproductive Isolation

Barriers preventing interbreeding between species

Pre-zygotic Isolation

Mechanisms preventing formation of zygotes between species

Habitat Isolation

Species occupy different habitats and rarely encounter each other

Temporal Isolation

Breeding occurs at different times, e.g., blackbird species

Behavioral Isolation

Different courtship rituals prevent mating

Mechanical Isolation

Structural differences in sex organs prevent mating

Species

Distinct forms within Linnean Hierarchy, e.g., Homo sapiens

Morphological Species Concept

Determines differences based on form, ignoring reproductive isolation

Phylogenetic Species Concept

Classifies species based on evolutionary relationships

Gametic Isolation

Chemical incompatibility of sperm and egg prevents fertilization

Post-zygotic Isolation

Barriers preventing hybrid offspring viability or fertility

Hybrid Inviability

Genetic differences lead to incomplete development in hybrids

Hybrid Sterility

Hybrids survive but cannot produce viable offspring due to chromosome mismatch

Speciation

Process where one species splits into two distinct species

Allopatric Speciation

Species formation due to geographic barriers

Sympatric Speciation

Species evolve within the same area without spatial separation

Dispersal

Migration leading to new populations and potential speciation

Adaptive Radiation

Diversification of a species into multiple forms to exploit different niches

Vicariance

Geographic barrier leading to speciation, e.g., Galapagos finches

Resource Partitioning

Species divide resources to reduce competition and promote coexistence

Hybridization

Interbreeding leading to new species, common in plants

Reinforcement

Selection for traits that enhance reproductive isolation

Gene Flow

Transfer of genetic material between populations, affecting speciation