| A | B |
|---|
| Adaptive radiation | *The rapid spread of form from an ancestral group that gives rise to a number of descendants that occupy a new niche |
| gradualism | *the transition of one species to another over millions of years |
| divergent evolution | *diversification of a common ancestral species into two or more species |
| convergent evolution | *Two or more types evolve toward great resemblance of each other in response to similiar niches and selection pressurs |
| coevolution | *Occurs between two species that have relationship |
| punctuated equilibrium | *evolutionary process characterised by long periods of little change, punctuated by short bursts of rapid evoultion. Which produce new species quite rapidly. |
| allopatric speciation | *is when a species population is seperated by a geographical barrier. |
| sympatric speciation | *Occurs when a sub-population become reproductivly isolated in the midst of a parent population. |
| reproductive isolation | *Pre zygotic and post zygotic |
| ring species | *A cline where two extremes are geogarphicly close. interbreeding is possible between neighbouring demes not possible with other demes |
| natural selection | *survival of the fittest, the organsim best adapted for survival in its niche will be more successful |
| adaption | *change in organism to suit change in environment governed by natural selection |
| geographical isolation | *A change in the environment that prevent gene flow between the isolated population and the parent population |
| ecological isolation | *Populations may have develped genetic differences to cope with different ecological niches or habitats. |
| polyploidy | *mutation producing more than twice the normal haploid number of chromosomes therefore creating variation in the gene pool |
| demes | *local populations with limited geneflow with other demes phenoytopic variations reflect local natural selection pressures |
| analogus structures | *organs and structures are essentailly the same but evolved independently from different ancestral organs |
| clines | *variation of phenotypic charcteristics of individuals of same species due to geographical variation |
| sequential species | *species seperated by time rather than space distighished by anatomical differences rather than ability to reproduce successfully |
| geographical separation | *some species can interbeed successfully in captivity when organisms are geograpicly separate |
| Pre zygotic mechanisms | *Act to prevent fertilisation between species |
| Post zygotic organisms | *Even when a sperm does fertilise an egg of another species, the zygote may notdevelop |
| parallel evolution | *similar features evolve in related or unrelated species becauses of similar selection pressures |
| Hybrid inviability | *even when sperm does fuse with an egg of another species deveoplment usually does not go to completition |
