RIMS
The two types of RIMS
What are pre and post zygotic mechanisms?
The process by which new species evolve from a single ancestral species by reproductive isolation, whilst both still inhabit the same geographical region.
What is sympatric speciation?
Features similar ancestral origin but have different functions due to differing selection pressures.
What are homologous structures?
Where two or more species affect each other’s evolution by acting as selection pressures on each other.
What is co-evolution?
A type of natural selection where individuals at one extreme of a phenotype distribution in a population have higher survival and reproduction rates than the rest of the population.
What is directional selection?
two species do not mate due to a river
What is a geographical barrier/isolating mechanism?
speciation where geographic isolation disrupts gene flow between two populations of a species resulting in evolution into different species.
What is allopatric speciation?
A permanent change in DNA or genetic material. (Only important to evolution if heritable.
What is a mutation?
where two of more populations of a species are exposed to different selection pressures and evolve distinct phenotypes over time, becoming increasingly different from each.
What is divergent evolution?
A new colony is started by a few members of an original population in a new location. Allele frequencies of the new population are not representative of the allele frequencies of the original population and rare alleles may become fixed or lost.
What is the founder effect?
Not mating due to different bird songs
What is a behavioural isolating mechanism?
No gene flow
What is needed for a new species to form?
Traits in different and unrelated species that have similar functions but have evolved independently due to similar selection pressures.
What are analogous structures?
The evolution of similar phenotypes by species of different ancestral origins due to similar selection pressures.
What is convergent evolution?
A type of natural selection where extreme phenotypes are favoured over average phenotypes, potentially leading to a population splitting into distinct groups.
What is disruptive selection?
When the first generation of a hybrid is fertile but the second is not.
What is hybrid breakdown?
A gradual change in the frequency of an allele or the average value of a phenotype across a geographical area.
What is a cline?
An anatomical feature that has no apparent function but resembles a structure of a presumed ancestor.
What is a vestigial structure?
The evolution of new species by gradual accumulation of small genetic changes over long periods of time.
What is gradualism?
The ability of an individual to successfully reproduce and pass on their genetics.
What is fitness?
When a hydrid fails to progress to a living organisms
What is hybrid inviability?
A series of geographically distributed populations that exhibit a gradual change in phenotypes away from the oldest population. Neighbouring populations are able to interbreed, but the extreme ends of the series, while geographically close, are unable to interbreed.
What is a ring species?
Circular DNA not found in the nucleus. 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.
What is mtDNA?
Long periods of little change in a species evolution followed by short bursts of speciation due to rapid change in the environment or selection pressures.
What is punctuated equilibrium?
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.
What is genetic drift?