3678984
Description
Flashcards by Taylor Gauld, updated more than 1 year ago
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Created by Taylor Gauld
over 8 years ago
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| Question | Answer |
| Define species | A group of organisms that normally interbreed in nature to produce fertile offspring |
| What is biological evolution | The genetic change in a population from one generation to another |
| The formation of a new species | Speciation |
| What is a Deme | A local population that has no or limited gene flow with other populaitons |
| What is a cline | A species that occupies a large geographical range where the environment varies therefore resulting in variation within the population |
| Ring Species | Where a species is distributed in a Cline where the two ends join, therefore resulting in a huge variation between the first and last species, sometimes resulting in two separate non breeding species with intermediate species connecting the two |
| Two types of gene flow | Immigration and Emigration |
| Effects of Immigration | An increase in new and different alleles into the population changing allele frequencies and increasing variation, therefore benefiting the population as they are more adaptable to changing environments. (hybrid vigor) |
| Effects of Emigration | Alleles leave the gene pool. Therefore deceasing genetic variation of the population. |
| Effects of inbreeding | Inbreeding causes more homozygotes to be produced therefore allowing for dangerous recessive alleles to be expressed, while also making disadvantageous alleles subject to selection and causing alleles to be eliminated from the population while decreasing genetic variation in the population |
| What is genetic drift | The elimination of alleles from the population due to chance. Small populations are particularly susceptible |
| What is the bottle neck effect | Where a population is dramatically reduced in size leaving only a small and reduced gene pool for the population to recover from, thus reducing genetic variability |
| What is the founder effect | Where a small group of individuals are isolated from the main population therefore producing a founder population with only a small amount of genetic variation to begin with. |
| What are the advantages of out breeding | Out-breeding tends to increase the number of hetero-zygotes in a population and reduce the chances of unfavorable or harmful recessive alleles coming together, while also maintaining genetic diversity. |
| Define natural selection | Where a population has an abundance, so there is competition for resources. There is a variety of alleles of which some are beneficial and allow individuals to survive longer and therefore reproduce more often causing the successful alleles to be passed on more often and increasing their frequency in the gene pool and the population |
| Environmental factors both biotic and abiotic that influence the survival of an individual | Selection pressures |
| Directional selection | |
| Stabilising selection | |
| Disruptive selection | |
| Where one sex decides what traits are attractive and then chose individuals to mate with based on which one is most atractive | Sexual selection |
| Sympatric speciation | Where speciation occurs between species that share the same environment |
| Allopatric speciation | Where speciation occurs between two species that are isolated physically |
| Name some Prezygotic mechanisms | Behavioral, Temporal, Geographical, structural, gametal, ecological. |
| Name some post zygotic isolating mechanisms | Hybrid invalidity, hybrid sterility, hybrid break down |
| Importance of RIMs | Reproductive isolating mechanisms are useful in speciation as they cause gene flow to be restricted allowing genetic differences to accumulate over time |
| When did the southern alps form | 2mya |
| When did New Zealand separate from Australia | 80 Mya |
| When did glaciation occure | 2.6 Mya |
| Explain Gradualism | Gradualism is a form of evolution where constant environmental pressures act on individuals causing beneficial alleles to be selected and therefore causing a change in the population over time |
| Explain Punctuated equilibrium | Is long periods of evolutionary stasis followed by short and rapid bursts of evolution. |
| Explain divergent evolution | Divergence occurs when two or more species result from a common ancestor |
| Describe adaptive radiation | adaptive radiation is a type of evolution that is rapid and involves a number of species diverging from a common ancestor when a variety of different ecological niches that may have become available suddenly |
| Describe convergent evolution | Convergent evolution involves two previously unrelated species that share no common ancestor, evolving along the same path to have similar physical features as a result of occupying the same ecological niche |
| Structures that look the same on the outside but come from unrelated ancestors | Analogous structures |
| Structures that look superficially different but are structurally similar and have come form a common ancestor | Homologous structure, eg. the pentadactyl limb found in most mamals |
| Describe co-evolution | Co-evolution occurs between two unrelated species that are part of a inter specific relationship. Both organisms rely upon the other or are affected by the other. So any evolution in one organisms will act as a selection pressure for the other |
| How is Mitochondrial DNA used | Mitochondrial DNA is special because it is passed along the maternal line and does not undergo any meiosis. Therefore the only mutations that occur are point mutations that occur at a constant rate. These the rate of these mutations allows scientists to measure the time since a mutation occurred as they are constant. Therefore scientists are able to identify when two species last shared a common ancestor. |
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