NCEA LEVEL 3 BIO SPECIATION

Species

individuals that normally interbreed to produce fertile offspring's and belong to the same gene pool

Allopatric Speciation

capable of interbreeding but cannot due to geographical isolation

Prezygotic, Postzygotic

Two types of reproductive barriers

Hybrid inviability

A zygote is formed but does not develop properly

Ring Species

connected by a series of intermediate geographical and structural subspecies between which interbreeding can occur

Covergent evolution

development of similar structures in UNRELATED ORGANISMS

Analogous structures

Structures that are similar but have evolved in different ways

Divergent Evolution

common ancestors divide into two or more lines with dissimilar characteristics due to environment

Parallel Evolution

development of related species along similar evolutionary paths due to strong selective pressure acting on all them in the same way of

Hybrid Sterility

A hybrid forms but is sterile e.g a sterile mule

Evolution

gradual process by which the present diversity of plants and animals arose form the earliest and most primitive organisms

Cline

increase in numbers of forms ofvariation in the characteristics of a species or population over its geographical range

Homologous structures

similar evolutionary history but have developed to suit different functions e.g wing of bat, flippers of dolphin

Postzygotic

RIMS acts as fertilization to prevent exchange of genes between populations, by repairing development or fertility of offspring

Adaptive Radiation

form of divergent evolution in which there is a rapid increase in numbers of forms from an ancestral type because of the sudden availability of niches.

Sympatric Speciation

Speciation occurring where organisms living in the same area are theoretically capable of interbreeding, but cannot because of difference in behavior, flowering times

Instant Speciation

Formation of new species thru autopolyploidy or allopolyploidy, because the chromosome numbers of new "instant" species DO NOT match that of the original species, they cannot interbreed

Founder effect

A chance change in allele frequency which occurs when a small group of individuals become detached from the main population

Punctuated equilibrium

long periods of little evolutionary change (stasis) interrupted by short bursts of rapid speciation

Hybrid breakdown

The hybrid offspring are fertile but produce infertile or non viable offspring

Geological record

Fossils persevered in sedimentary rock layers that ca be used to trace evolutionary history of a species

Stabilizing selection

Natural selection acting against the extremes of a range of variation, resulting in resistance to change in allele frequencies

Macro-evolution

The formation of a completely new species, genera etc

Natural selection

process that brings about new species by the elimination of the less adapted individuals and the survival of the organisms which are better adapted

Vestigial organ

Any part of an organism that has diminished in size during its evolution because the function it serves has decreased in importance, e.g appendix in humans

Reproductive Isolation Mechanisms

A barrier to breeding that exist due to differences in mating seasons or mating organisms

Polyploidy

Mutation producing more than twice the normal haploid number of chromosomes

Micro-evolution

accumulation of (through mutation) new characteristics in a species

Disruptive selection

Natural selection acting against the middle of a range of variaton

Prezygotic

RIMs that acts to prevent the fusion of gametes from different populations

Gradualism

Evolution proceeds slowly but continuously. Eventually the accumulated changes result in speciation

Genetic Drift

The change in allele frequency due to the accumulated effects of chance

Directional selection

Natural selection against one end of a range of variation, resulting in a progressive change in allele frequency

Endemic

Found only in that country