Genetic Bottleneck
Big events that cause drastic reduction in a parent pop leaving a surviving pop w/ v. low genetic diversity (unless they mutate)
Key Terms
Genetic Bottleneck
Big events that cause drastic reduction in a parent pop leaving a surviving pop w/ v. low genetic diversity (unless they mutate)
Events that may cause genetic bottleneck
Overhunting to the point of extinction
Habitat destruction
Natural disasters
Process leading to Genetic Bottleneck
Orig population
Large no. die
Reduced population (some alleles lost)
Reproduction
New population w/ low genetic diversity
Order of conservation
Habitat
Population
Genes
Artifical selection and selective breeding
Humans use animal and plant breding to selectively develop particular phenotypic ratios by choosing spp individuals
Occurs over several gener...
Agent of selection in natural selection
Environment
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| Term | Definition |
|---|---|
Genetic Bottleneck | Big events that cause drastic reduction in a parent pop leaving a surviving pop w/ v. low genetic diversity (unless they mutate) |
Events that may cause genetic bottleneck | Overhunting to the point of extinction Habitat destruction Natural disasters |
Process leading to Genetic Bottleneck | Orig population Large no. die Reduced population (some alleles lost) Reproduction New population w/ low genetic diversity |
Order of conservation | Habitat Population Genes |
Artifical selection and selective breeding | Humans use animal and plant breding to selectively develop particular phenotypic ratios by choosing spp individuals Occurs over several generations |
Agent of selection in natural selection | Environment |
Agent of selection in artifiicial selection | Human |
Effect of allele frequencies in selection | Changes for both natural and artificial |
Effect of evolution due to natural selection | Drives it |
Effect of evolution due to artificial selection | Drives it then slows it down |
Speed of natural selection | Slow |
Speed of artifical selection | Fast |
Ethical considerations w artificial selection and selective breeding | Health problems; certain traits may be exaggerated Reduction of genetic diversity - more susceptible to genetic diseases caused by r alleles, potentially useful alleles for the future lost |
Speciation | Formation of new and distinct species through the course of evolution |
Factors that may cause directional selection | Predation Habitat changes Competition |
Environments that cause directional selection | Slowly changing environmental conditions in one direction |
'Ingredients' for speciation | Existing genetically varying poulation Isolation: geographical or reproductive Time Different selective pressures Large change in allele frequencies |
Why do you need diff selective pressures for speciation | Changes allele frequencies in diff directions |
Allopatric speciation | Geographically isolated | Gene pool is physically separated so the sep pop can then evolve independently of each other |
What causes changes in allele frequency in allopatric speciation | Accumulation of diff mutations forms separate gene pools Different biotic/ abiotic factors Differential reproductive successes |
Sympatric speciation | Reproductively isolated Organisms inhabiting same area separated into 2 or more groups due to changes in alelles and phenotypes preventing them from successfully breeeding together |
Examples of things causing reproductive isolation | Seasonal changes (Different flowering seasons) Mechanical changes (Changes in genitalia) Behavioural changes (Diff courtship rituals) |
How does the presence of epistatic alleles inhibit the expression of the hypostatic allele | Epistatic allele codes for repressor protein/ TF Product of epistatic allele binds to promoter of hypostatic allele Product stops transcription or inhibits enzyme action of enzyme encoded by A |
Causes of variation in continuous variables e.g. height | Environment Age Polygenic |
Result of speciation | Gene flow restricted | Leads to diff specialisation |