Reproductive Isolation and Speciation Mechanisms

Reproductive Isolation

Factors that prevent species from interbreeding.

Prezygotic Isolating Factors

Factors that act before the fertilization of an egg.

Postzygotic Isolating Factors

Factors that come into play after fertilization.

Geographic Isolation

Isolation due to physical separation in space.

Ecological Isolation

Isolation due to habitat preferences.

Temporal Isolation

Isolation due to species being active at different times.

Behavioral Isolation

Isolation based on specific courtship rituals or behaviors.

Gametic Isolation

Incompatibility between gametes preventing fertilization.

Mechanical Isolation

Physical incompatibility preventing mating.

Hybrid Inviability

Embryo forms but does not fully develop.

Hybrid Sterility

Offspring are produced but are sterile.

Speciation

The process by which new species arise.

Genetic Divergence

The accumulation of genetic differences between populations.

Drosophila melanogaster

A species of fruit fly known for its specific mating compatibility.

Haliotis rufescens

A species of abalone that only fertilizes its own eggs.

H. corrugata

A closely related species of abalone that is not fertilized by H. rufescens.

Polar Bears

A species that has been observed to hybridize with grizzly bears due to loss of geographic isolation.

Grizzly Bears

A species that has expanded its range northward, leading to potential hybridization with polar bears.

Mule

A hybrid offspring of a horse and a donkey that is typically sterile.

Chromosome Numbers

Horses have a haploid complement of 32 and donkeys have 31.

Courtship Rituals

Specific behaviors that individuals perform to attract mates.

Natural Hybrids

Offspring resulting from the mating of two different species.

Viable Offspring

Offspring that are capable of surviving and reproducing.

Embryo Development

The process by which a fertilized egg develops into a mature organism.

Species Concept

The definition and criteria used to identify and classify species.

Gene Flow

The transfer of genetic material between populations.

BSC (Biological Species Concept)

A concept that defines species based on reproductive isolation.

Genetic Drift

Random changes in allele frequencies over time.

Natural Selection

Process where organisms better adapted survive.

Allopatric Speciation

Speciation due to geographic separation of populations.

Geographic Barrier

Physical separation preventing gene flow between populations.

Subspecies

Distinct population within a species, often geographically isolated.

Dispersal

Movement of individuals to new locations.

Vicariance

Geographic barrier arises within a population.

Hybrid Offspring

Offspring produced from interbreeding of different populations.

Reduced Fertility

Lower reproductive success of hybrid offspring.

Isthmus of Panama

Landmass formed 3.5 million years ago, separating marine species.

Phylogeny

Evolutionary history and relationships among species.

Marine Corridors

Open water routes allowing interbreeding between populations.

Daughter Species

Species that arise from a common ancestor.

Taxonomists

Scientists who classify organisms into categories.

Population-Specific Traits

Unique characteristics that develop in isolated populations.

Extensive Genetic Differences

Significant variations in DNA between populations.

Galápagos Finches

Example of dispersal leading to speciation.

Fertile Offspring

Offspring capable of reproducing successfully.

Evolutionary Tree

Diagram showing evolutionary relationships among species.

Caribbean and Pacific Species

Separated marine populations due to the Isthmus formation.

Genetic Isolation

Separation preventing gene flow between populations.

Hybrid Viability

Ability of hybrid offspring to survive to adulthood.

Partial Reproductive Isolation

Some interbreeding possible, but reduced success.

Evolutionary Models

Theoretical frameworks explaining speciation processes.

Marine Biologist

Scientist studying marine organisms and their environments.

Genetic Fixation

Process where a mutation becomes predominant in a population.

Alpheus

Genus of shrimp illustrating speciation events.

Speciation Rate

Rate at which new species evolve over time.

Peripatric Speciation

Speciation occurring in isolated peripheral populations.

Tanysiptera galatea

Kingfisher species showing peripatric differentiation.

Adaptive Radiation

Rapid diversification of species in new environments.

Galápagos Islands

Location of significant finch speciation studies.

Darwin's Finches

Group of finch species evolved in Galápagos.

Ecological Opportunities

Available resources promoting species diversification.

Medium-Seeds Specialists

Finches originally adapted to medium-sized seeds.

Bill Size Spectrum

Variation in finch beak sizes related to food sources.

Stabilizing Selection

Natural selection favoring average traits in populations.

Isolation Duration

Time species have been separated, at least 3 million years.

Phylogenetic Tree

Diagram showing evolutionary relationships among species.

Environmental Differences

Variations in habitat affecting species evolution.

Dispersal Events

Occurrences of species moving to new locations.

Galápagos Finch Evolution

Process leading to multiple finch species from a common ancestor.

D.J. Futuyma

Author of referenced evolutionary studies.

Peter and Rosemary Grant

Researchers studying Galápagos finch speciation.

Mitochondrial DNA

Genetic material used to study evolutionary relationships.

Speciation Events

Occurrences of new species arising from ancestral populations.

Island Population

Small, isolated group evolving separately from mainland.

Geographic Separation

Physical barriers preventing species interbreeding.

Ecological Opportunity

Availability of resources allowing species diversification.

Co-speciation

Simultaneous speciation in two interdependent species.

Sympatric Speciation

Speciation occurring without physical separation.

Disruptive Selection

Natural selection favoring extreme phenotypes over intermediates.

Phylogenetic Trees

Diagrams showing evolutionary relationships among species.

Medium-billed Birds

Finches with average bill sizes affected by selection.

Host-parasite Relationship

Interaction where one organism benefits at another's expense.

Intermediate Phenotypes

Traits that are average between two extremes.

Physical Separation

Geographic barriers preventing gene flow between populations.

Hybrid Individuals

Offspring resulting from the mating of different populations.

Medium-sized Seeds

Seeds that are not favored in certain environments.

Finch-like Birds

Birds that exhibit specialized feeding behaviors.

Lord Howe Island

Location providing evidence for sympatric speciation in plants.

Divergence

Process where two populations become genetically distinct.

Competitive Exclusion

Theory stating two species competing for the same resources cannot coexist.

Extremes of Bill Size

Large and small bill sizes favored by selection.

Ecological Niche

Role and position a species has in its environment.

Isolation Mechanisms

Factors preventing interbreeding between populations.

Phenotypic Variation

Differences in physical traits among individuals of a species.

Evolutionary Context

Understanding biological processes in relation to evolutionary history.

Instantaneous Speciation

Speciation occurring in a single generation.

Hybridization

Crossbreeding between two different species.

Reproductively Isolated

Offspring cannot breed with parent species.

Tetraploid

Organism with four sets of chromosomes.

Allopolyploid

Polyploid formed from hybridization of different species.