What is the definition of a species?
Group of living organisms that can reproduce withe each other and produce fertile offspring.
What is the definition of speciation?
Speciation is the process by which new species are formed from
ancestral ones / existing species.
What is the definition of genetic drift?
Genetic drift is the random fluctuations in the frequencies of
alleles from generation to generation due to chance events.
What is the definition of gene flow?
Gene flow is when individuals move between populations, and
this allows new mutations / new combinations of alleles to
move into each population; thus the species does not diverge
What does RIM stand for? And what is it?
Reproductive Isolating Mechanisms. Biological or behavioural characteristics that prevent different species from interbreeding and producing fertile offspring.
Define sequential evolution
A single common ancestor, which becomes another species over time.
Define divergent evolution
Single common ancestor which breaks off into two new species, each with different niches
Define convergent evolution
2 unrelated species evolve to have similar features due to similar selection pressures, to fill similar niches.
Define adaptive radiation
Single common ancestor diverging into a large number of new species
Define pre zygotic isolation mechanisms?
Prezygotic isolating mechanisms are those that prevent successful
fusing of gametes.
What are the pre zygotic isolation mechanisms?
- Chemical isolation
- Temporal isolation
- Mechanical isolation
- Geographic isolation
- Gametic isolation
- Behavioural isolation
Define post zygotic isolation mechanisms?
Barriers hat occur after fertilisatio has occurred that prevent a hybrid offspring from being viable or fertile.
What are the post zygotic isolation mechanisms?
- Hybrid inviability
- Hybrid sterility
- Hybrid breakdown
What is punctuated equilibrium?
Species changing very little over long periods of time, then changing rapidly. Long periods of stasis with sudden speciation.
What is gradualism?
Slow genetic change over time due to conditions changing slowly therefore selection pressures not being intense.
Define sympatric speciation
New species forming within the same area as the parent species
Define allopatric speciation
Formation of new species due to geographic separation.
Define polyploidy
The cells of an organism having more than 2 paired sets of homologous chromosomes
What is an autopolyploid?
A polyploid involving the duplication of chromosomes from a single species.
What is an allopolyploid?
A polyploid involving the duplication of chromosomes in a hybrid between two species.
What is an amphiploid?
The result of the last stage of allopolyploidy where a fertile hybrid is formed by the doubling of chromosomes in a hybrid.
Define co-evolution
Two species that have a partnership or symbiotic relationship that evolve together to continue the relationship.
Define natural selection
The process of organisms with beneficial traits to a specific election pressure surviving and reproducing to pass their allele onto offspring.
What is a mutation?
A permanent change to the DNA of a living organism. Can be harmful, neutral or beneficial depending on selection pressures.
