NCEA Bio Level 3 - Speciation

Species

group of organisms that can naturally interbreed to produce a fertile offspring

Selection Pressures

Factors in the enviroment that influences organisms ability to survive and reproduce

Genetic Variation

Differences in DNA among organisms within a specie or population

Stablising Selection

Favours the average over the extremes 

natural selection

inheirtable traits are more likely to survive long enough and reproduce.

founder effect

small population becomes isolated from the original population.

Bottleneck effect

when population suddenly reduced in size due to a natural disaster or human impact

covergent evolution

unrelated species that have similar niches/enviroments - experience same selection pressures = evolve similar adaptions

parallel evolution

2 or more related specie groups evolve along similar lines indpendently

allopatric speciation

speciation that occurs in different geographical areas 

adaptive radiation

when a large number of species diverge from a common ancestor, each occupies a different niche.

gradualism

slow, constant rate of change within species occurs overtime due to selection pressure

sympatric speciation

2 groups reproductively isolated but not geographically isolated. 

• slow

• instat speication = polyploid

polyploid

cells have more than 2n chromosomes from mutations = instant speciation

Allopolyploid cells

muliplication of chromosomes within single species. Cell fails to divide during meiosis creating 2n gametes which are nondisfuncational.

autopolyploid

having more than 2 haploid cells chromosomes that are derived from the same ancestral species. 

prezygotic isolation

mechicanisms that prevent 2 different species from amting and producing offspring

post zygotic isolation

biological barriers that act after a successful fertilzation.

hybird inviabilty

zygote forms but embryo cant develop = hybird dies

hybird sterilebility

zygote forms and hybird survivable but is sterile

hybird breakdown

2 different species can reproduce = hybird (fertile + can reproduce) but next gen gets reduced fertilty. 

ecological isloation

same area but different habitat

temporal isloation

specific speices breed at the same time

behavioural isolation

specfic actions - courtship behaviour

gametic isloation

reproduction occurs - sperm/egg incompatible = no fertilzation

strutural isolation

unable to breed due to reproductive organs

gene flow

movement of genetic material where alleles from 1 population move to another

co evolution

change in feature of 1 species that acts as selection pressure for a change in feature of another speices

punctuated equilibrium

sudden bursts of rapid selection (happens in 1000 years rather than millions)

genetic drift

random changes in the alelle frequency because of a small population size

disruptive selection

favours both extremes over average

comparative anatomy

comparison of body strutures between different speices

divergent evolution

2 or more speice groups result with common ancestor

directional selection

favours one extreme over average or other extreme

analogus struture

different origins but have evolved similar function

homologus struture

have the same orgin but have evolved different functions 

speciation

formation of new species

pattern of evolution

different species living in similar enviroment come to look similar