Bio Genetics

Adaptations

Phenotypes that allow an organism to better survive in its

environment.

Adaptive radiation

A single ancestral species evolves into a diverse array of descendant species, each adapted to a specific ecological niche. (Can also be divergent evolution.)

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

Geographic isolation disrupts gene flow between two populations of a species resulting in speciation

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 organism formed when two different species breed. It is initially sterile but becomes fertile after chromosome doubling, giving it two sets of homologous chromosomes.

Analogous structures

Traits in different and unrelated species that have similar functions but have evolved seperatly 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

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

Behavioural

adaptation

A species specific way of responding to the environment 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 expert selection pressures on eachother, so they each evolve to adapt to the selection pressures

Convergent evolution

Different species develop similar characteristics because they experience 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 (range of characteristics) in a population have higher survival and reproduction rates than the rest of the population.

Disruptive selection

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

Divergent evolution

Different populations of the same species experience different selection pressures and develop different characteristics over time. This can lead to speciation.

Ecological equivalents

Species that inhabit the same niche but in different geographical areas. They will compete if put in the same environment. For example, katipō and white-tailed spiders.

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 speciation.

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 small group starts a new population in a different location. Its allele frequencies may differ from the original population, and rare alleles may become more commen, fixed or disappear.

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. (Genes immigrate into and/or emigrate out of the population.)

Gene pool

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

Genome

The complete genetic make up 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 of 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 when F2 and later hybrid generations have lower fitness or survival than the F1 generation.

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.

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

Selection pressures favour individuals with inherited characteristics that help them survive and reproduce. Over generations, these beneficial alleles become more common in the population.

Niche

The habitat and ecological role of an organism.

Non-Random Mating

Occurs when individuals with specific phenotypes are mated by preferance.

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

Punctuated

equilibrium

Long periods small genetic changes in a speices 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.

Reproductive

Isolating Mechanism

An inherited feature or mechanism that prevents different species from breeding and producing viable, fertile offspring.

Ring species

Populations spread across different locations gradually develop different characteristics. Neighbouring populations can interbreed, but the populations at opposite ends cannot.

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 produces 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 average characteristics are favoured over rare characteristics, causing variation in the population to decrease.

Morphological

isolating barrier

When reproductive structures between related species are incompatible.

Sympatric speciation

New species form from one original species in the same geographical area because they become unable to reproduce with each other.

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 physical 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.