BIOLOGY SPECIATION

Adaptations

Phenotypes that allow an organism to better survive in its environment.

Adaptive radiation

The process of a single ancestral species evolving into a diverse array of descendant species, each adapted to a specific ecological niche.

Allele frequency

The proportion of an allele for a specific gene in a gene pool.

Alleles

Alternative forms of a gene, such as black or chestnut coat colour in horses.

Allopatric speciation

A type of speciation where geographic isolation disrupts gene flow between populations, resulting in evolution into different species.

Allopatric species

Similar species that are reproductively isolated due to geographic separation.

Allopolyploid

An organism that contains two or more sets of chromosomes from two or more different species.

Amphiploid

A sterile hybrid formed by crossing two different species that becomes fertile through nondisjunction.

Analogous structures

Traits in different unrelated species that have similar functions but evolved independently.

Asexual reproduction

A single parent copies itself to form genetically identical offspring.

Autopolyploid

Having more than two sets of chromosomes from a single species.

Biogeography

The study of the geographical distribution of species.

Bottleneck effect

A drastic reduction in population size leading to a loss of alleles and genetic diversity.

Behavioural adaptation

Specific responses to the environment that enhance survival.

Characteristics

Features or traits of an organism.

Clade

A grouping or branch of a taxonomic tree including a common ancestor and all its descendants.

Cline

A gradual change in allele frequency or phenotype across a geographical area.

Co-evolution

When two or more species affect each other's evolution through selection pressures.

Convergent evolution

The evolution of similar phenotypes from species of different ancestral origins.

Deme

A sub-population within a larger population that is partly isolated from interbreeding.

Directional selection

Natural selection favoring individuals at one extreme of a phenotype distribution.

Disruptive selection

Natural selection where extreme phenotypes are favored over average phenotypes.

Divergent evolution

The process where populations exposed to different selection pressures evolve distinct phenotypes.

Ecological equivalents

Species inhabiting the same niche in different geographical areas.

Endemic

Species occurring naturally in only a specific location.

Evolution

Gradual change in the genetic code of populations over time.

Extant

Species with living members.

Extinct

Species with no living members.

Fertilisation

The combining of sperm and egg to form a zygote.

Fitness

The ability of an individual to successfully reproduce and pass on genetics.

Fitness Cost

The loss of non-target alleles in a gene pool due to natural selection.

Foetus

An unborn developing offspring.

Founder effect

Allele frequencies in a new population started by a few individuals may not represent the original population.

Gametes

Sex cells containing half the chromosomes of the parent.

Gause's Competitive Exclusion Principle

No two species can occupy the same ecological niche without one being excluded.

Gene flow

Migration between populations that changes genetic composition.

Gene pool

The complete set of genes and their alleles in a population.

Genome

The complete genetic composition of an individual or species.

Genotype

An individual's allele combination for a phenotype.

Genetic diversity

Variation of alleles and traits in a population.

Genetic drift

Random changes in allele frequency in small populations due to chance.

Genetic variation

The variation of alleles and heritable traits in a population.

Geographical isolation

Physical features preventing gene flow between populations.

Gradualism

The gradual accumulation of small changes leading to new species.

Homologous structures

Features with similar ancestral origins but different functions due to selection pressures.

Hybrid

An individual formed by crossing two different species.

Hybrid breakdown

Decline in fitness of hybrid offspring in later generations.

Hybrid inviability

Hybrids fail to develop into healthy adults.

Hybrid sterility

Hybrids reach maturity but cannot produce viable offspring.

Introduced species

A species moved by humans to a new ecosystem.

Reproductive isolating mechanism

Features preventing interbreeding between species.

Mitochondrial DNA

Circular DNA in mitochondria passed down maternal lines.

Mutation

A permanent change in DNA or genetic material.

Natural selection

The process where individuals with advantageous traits survive to reproduce.

Niche

The habitat and ecological role of an organism.

Non-Random Mating

Individuals with specific phenotypes are mated preferentially.

Organism

A living thing.

Ovulation

Cyclical production of ova.

Phenotype

The expression of a gene as a trait.

Phylogenetic tree

A diagram describing evolutionary relationships among species.

Polyploidy

Having three or more sets of homologous chromosomes.

Population

A number of organisms of the same species in a defined area.

Prezygotic isolating mechanism

Mechanism preventing species from interbreeding before fertilization.

Post-zygotic mechanism

Mechanism preventing species from interbreeding after fertilization.

Punctuated equilibrium

Long periods of little change followed by rapid bursts of speciation.

Reproduction

The production of offspring.

Reproductive Isolating Mechanism

Mechanisms preventing different species from interbreeding.

Ring species

Geographically distributed populations demonstrating gradual phenotype changes.

Selection pressures

Environmental factors affecting fitness and survival.

Sexual reproduction

Combining genetic information from two parents.

Sexual selection

Individuals more successful at attracting mates produce more offspring.

Speciation

The process by which one species gives rise to two or more new species.

Species

A group of organisms that can breed and produce fertile offspring.

Stabilising selection

Natural selection favoring average phenotypes over extreme ones.

Morphological isolating barrier

Incompatibility of reproductive structures between related species.

Sympatric speciation

New species evolve by reproductive isolation while in the same region.

Sympatric species

Similar species living in the same area but are reproductively isolated.

Taxonomy

The science of naming, describing, and classifying organisms.

Temporal isolating mechanism

Reproductive isolation due to activity at different times.

Trait

A feature of an organism.

Vestigial structure

An anatomical feature with no apparent function, resembling an ancestor's structure.

Y-chromosome

A nuclear chromosome passed down through the male line.

Zygote

The fertilised egg or ovum.