Speciation Flashcards
(29 cards)
Speciation
The process where a group of individuals within a population become reproductively isolated to their larger population forming a new species
Species
a group of organisms that interbreed under natural conditions and are reproductively isolated from other species.
pre-zygotic RIMs
Geographic
Ecological
behavioural
gametic
mechanical
temporal
post zygotic RIMs
hybrid breakdown, inviability and sterility.
polyploidy
Where an organism has more than two sets of chromosomes in its somatic cells (>2n).
Autopolyploidy
Homologous chromosomes do not separate during meiosis, leading to diploid number of chromosomes present in the gametes
Allopolyploidy
The process where two different species produce an infertile hybrid. chromosome doubling can lead to new (instant) species
Deme
A subset of a population where there is limited gene flow with members of the larger population
Cline
The gradual change of characteristics between neighbouring populations related to the change in biotic and abiotic factors in a given range.
Genetic Flow
the transfer of genetic material from one population to another usually by migration
Genetic Drift
the process of change in genetic composition of a population due to chance or random events
Population bottleneck
A sharp reduction in the size of the population due to environmental events or human activities
founder effect
A small number of individuals emigrate from a population or become geographically isolated from their original population
divergent evolution
when two species diverge from a common ancestor and develop different characteristics.
homologous structures
structures that have similar evolutionary history but have developed to suit different functions
convergent evolution
The proc two different species evolve similar characteristics due to facing similar selction pressures.
analogous structures
Various structures in different species that have the same function but have evolved differently. They do not share a common ancestor
co-evolution
Changes in one species lead to reciprocal changes in another. They evolve together as they exert different selection pressures on each other.
gradualism
The process of evolution through the accumulation of many small changes at a regular rate over a very long period of time
punctuated equilibrium
evolution through periods of stasis punctuated by sudden change in species due to sudden changes in the environment
Adaptive radiation
The rapid formation of multiple new species diverging from a common ancestor to occupy newly available and different niches.
Natural Selection
The process whereby organisms better adapted to their environment tend to survive and produce more offspring
Disruptive selection
The outcome of natural selection against the phenotypic median favouring variants at opposite extremes of the trait
Directional selection
The outcome of natural selection against one extreme of a trait, shifting the phenotypic median to the other extreme.