NCEA Level 3 Speciation Vocab BEANZ

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 form of a gene. For example, black or chestnut coat colour in horses.

Allopatric speciation

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

Allopatric species

Where similar species 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 (sterile hybrid)

An amphiploid is formed by crossing two different species and is sterile. It undergoes nondisjunction in meiosis to become fertile, having two sets of homologous chromosomes, becoming an allopolyploid.

Analogous structures

Traits in different and unrelated species that have similar functions but have evolved independently due to similar selection pressures. For example, wings in birds and insects.

Asexual reproduction

A single parent copies itself to form a genetically identical offspring.

Autopolyploid

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

Biogeography

The study of the geographical distribution of extinct and modern species.

Bottleneck effect

The phenomenon in which a population is dramatically reduced in size, but then rebounds again. A consequence of the bottleneck effect is the loss of alleles in a population, reducing genetic diversity.

Behavioural adaptation

A way of responding to the environment that is specific to a species of organisms that allows the organism to better survive in its environment.

Characteristics

A feature of an organism (trait/phenotype).

Clade

A grouping or branch of a taxonomic tree that includes a common ancestor and all the descendants (living and extinct) of that ancestor.

Cline

A gradual change in the frequency of an allele or the average value of a phenotype across a geographical area.

Co-evolution

Where two or more species affect each other's evolution by acting as selection pressures on each other. For example, tūī beak shape and harakeke flower shape.

Convergent evolution

The evolution of similar phenotypes by species of different ancestral origins due to similar selection pressures. For example, penguins and fish both have torpedo shapes but have no genetic common ancestor.

Deme

A sub-population within a larger one that is partly isolated from interbreeding with other sub-populations present.

Directional selection

A type of natural selection where individuals at one extreme of a phenotype distribution in a population have higher survival and reproduction rates than the rest of the population.

Disruptive selection

A type of natural selection where extreme phenotypes are favoured over average phenotypes, potentially leading to a population splitting into distinct groups.

Divergent evolution

The process where two or more populations of a species are exposed to different selection pressures and evolve distinct phenotypes over time, becoming increasingly different from each. This process can lead to speciation.

Ecological equivalents

Species that inhabit the same niche but in different geographical areas.

Endemic

Species found naturally occurring in only a particular location. For example, kiwi in New Zealand.

Evolution

Gradual change in the genetic code of populations over a long period. May result in the formation of new species.

Extant

Species with members still living.

Extinct

Species with no living members.

Fitness

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

Fitness Cost

The loss of non-target alleles from a gene pool during the process of natural selection.

Founder effect

A new colony is started by a few members of an original population in a new location. Allele frequencies of the new population are not representative of the allele frequencies of the original population and rare alleles may become fixed or lost.

Gametes

Sex cells containing half the chromosomes of the parent.

Gause's Competitive Exclusion Principle

No two species can occupy the same ecological niche. One will either die or change niches.

Gene flow

Occurs when individuals migrate between different populations and cause changes in the genetic composition of the resulting populations. (Immigration into and emigration out of the population.)

Gene pool

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

Genome

The complete genetic composition of an individual or species.

Genotype

An individual's allele combination for a particular phenotype.

Genetic drift

The random change in a small population's allele frequency from one generation to the next, due to chance. Alleles may then be fixed or lost.

Genetic variation/diversity

The variation of alleles/heritable traits in a population of organisms.

Geographical isolation

Where any physical feature of the Earth prevents gene flow. For example, mountains, rivers or glaciers.

Gradualism

The evolution of new species by gradual accumulation of small genetic changes over long periods of time.

Homologous structures

Features similar ancestral origin but have different functions due to differing selection pressures. For example, arm of human and wing of bat.

Hybrid

Individual formed through crossing two different species where the offspring may be sterile or show hybrid vigour.

Hybrid breakdown

A reproductive isolating mechanism where there is a decline in the fitness or viability of hybrid offspring in later generations (F2 and beyond) compared to the first generation (F1) hybrids.

Hybrid inviability

A reproductive isolating mechanism where hybrids fail to develop into healthy, mature adults, either in utero or after birth.

Hybrid sterility

A reproductive isolating mechanism where the hybrid reaches maturity but cannot produce viable offspring. For example, mule.

Introduced species

A species moved by humans from a native ecosystem to another ecosystem.

Reproductive isolating mechanism

Inherited feature that tends to prevent species from interbreeding with other species.

Mitochondrial DNA

Circular DNA found in the mitochondria. Passed down through the maternal line. Does not undergo crossing-over. Has a relatively constant mutation rate and no proofreading. Can be used to compare relatedness of species.

Mutation

A permanent change in DNA or genetic material. (Only important to evolution if heritable.

Natural selection

The process by which selection pressures act on members of a population, and those individuals with heritable traits better suited to their environment, survive and reproduce more successfully than other members of their population, leading to an increase in the frequency of those advantageous alleles within a population over multiple generations.

Niche

The habitat and ecological role of an organism.

Non-Random Mating

Occurs when individuals with specific phenotypes are mated preferentially.

Phenotype

How a gene is expressed as a protein/characteristic/trait.

Phylogenetic tree

A diagram that describes the evolutionary relationships among various species.

Polyploidy

Where an organism has three or more sets of homologous chromosomes.

Population

Number of organisms of the same species living in a defined area.

Prezygotic isolating mechanism

A reproductive isolating mechanism that keeps species separate by acting before fertilisation occurs. For example, courtship differences.

Post-zygotic mechanism

A reproductive isolating mechanism that keeps species separated by acting after fertilisation. For example, infertile hybrid.

Punctuated equilibrium

Long periods of little change in a species evolution followed by short bursts of speciation due to rapid change in the environment or selection pressures.

Reproduction

The production of offspring, allowing genes to be passed on to subsequent generations.

Ring species

A series of geographically distributed populations that exhibit a gradual change in phenotypes away from the oldest population. Neighbouring populations are able to interbreed, but the extreme ends of the series, while geographically close, are unable to interbreed.

Selection pressures

Environmental factors that affect the fitness and survival of individuals within a population and changing allele frequencies. For example, resource scarcity, predation, or environmental pressures.

Sexual reproduction

The combining of genetic information from two parents results in genetically unique offspring.

Sexual selection

Some individuals are more successful at attracting mates and therefore produce more offspring. For example, peacocks with larger tails get more mating opportunities.

Speciation

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

Species

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

Stabilising selection

A type of natural selection where individuals with average or moderate phenotypes are more fit than those with extreme phenotypes, leading to a narrowing of the phenotypic variation in a population.

Morphological isolating barrier

When reproductive structures between related species are incompatible.

Sympatric speciation

The process by which new species evolve from a single ancestral species by reproductive isolation, whilst both still inhabit the same geographical region.

Sympatric species

Similar species living in the same geographical area but are reproductively isolated. For example, Gazelle and springbok on savannah.

Temporal isolating mechanism

When groups are reproductively isolated due to being active at different times of the day or seasons.

Trait

A feature of an organism (protein/phenotype/characteristic).

Vestigial structure

An anatomical feature that has no apparent function but resembles a structure of a presumed ancestor. For example, kiwi wing.

Y-chromosome

A nuclear chromosome passed down through the male line. Does not undergo crossing-over. It can be used to compare the relatedness of extant species and extinct species.

Zygote

The fertilised egg/ovum.