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Description
Flashcards by Taylor Gauld, updated more than 1 year ago
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Created by Taylor Gauld
over 9 years ago
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| Question | Answer |
| Describe Biological Evolution | The genetic change in a population from one generation to another |
| What is a species | A group of organisms that normally interbreeds to produce fertile offspring |
| The formation of a new species | Speciation |
| Population | Members of a species that live in the same geographical area and share a common gene pool |
| Name some ways that gene flow can occur | Migration (immigration and emigration) individuals from different populations breed together. Introducing different alleles into the population |
| Some advantages of gene flow | Introduces more alleles into the population meaning that more genetic variability in the gene pool |
| Disadvantages of gene flow | prevents reproductive isolation which leads to different species evolving, i.e. prevents evolution. Emigration can decrease genetic diversity |
| Explain genetic drift | The change in allele frequency within the population due to chance events. Limits genetic diversity and can eliminate alleles in small populations |
| Explain founder effect | A small number of plants or animals colonise a new area, with only a small gene pool there is likely to be less genetic variability |
| When a large population is suddenly reduced down in size due to a catastrophic event or human impact. Not selection pressures | Genetic bottleneck. genetic variation is decreased making the population vulnerable to extinction |
| Breeding with members of the same population can lead to reduced genetic variance and exposition of harmful recessive alleles tends to increase the number of homo-zygotes in a populaiton | Inbreeding |
| Out breeding | Breeding with members of other populations, introducing new alleles into the population and increasing genetic variability. Tends to increase the number of hetrozygotes, individuals tend to be more evolutionary fit as they have more alleles present. |
| What are selection pressures | Environmental factors, both biotic and abiotic that influence which individuals pass on their genes, this means either affecting their ability to survive or ability to reproduce. Different environments have different selection pressures |
| Explain natural selection | Certain alleles that increase an individual's chances of survival in an environment and enable that individual to reproduce and become more common over successive generations. |
| Stabilizing selection, extreme phenotypes are selected against and only the middle phenotypes survive, reducing phenotype range | |
| Directional selection, one extreme of phenotypes are selected for while the other is selected against resulting in a shift in phenotypes | |
| Disruptive selection, the middle phenotypes are selected against and extremes are selected for simultaneously, this can result in a speciation | |
| Sexual selection | A special type of selection, where one sex, usually females decides what characteristics are selected for. This means that these traits are more prevalent in the population. Sexual selection can counter natural selection because even though the trait is selected against is still gets passed on. |
| What is L.U.C.A | Last universal common ancestor. all organisms have a gene that codes for an RNA synthesis enzyme. |
| What is a mutation | Mutation is a sudden, relatively permanent change in the genetic material. |
| What are the two types of mutations | Point mutation, chromosomal |
| Explain a gene mutation | Where the order or bases is changed within a gene, such as base substitution, addition or deletion. Most are harmful, how ever some could produce new alleles |
| What is mitochondrial DNA | DNA found in the Mitochondria, that undergoes regular gene mutation which acts as a biological clock to compare the relatedness between organisms |
| Explain chromosomal mutations | Involves the replication, deletion, or fusion or different chromosomes. In evolution the most important role is to reproductive isolate individuals, can lead to instant speciation |
| Explain ploidy | Ploidy is the number of chromosomes in a cell. Chromosomal mutations can result in poly ploidy. |
| What is Aneuploidy | Where only a few chromosomes are represented an unusual number of times. Results from non dis junction occurring in meiosis |
| What is Euploidy | Variation in the number of chromosomes represented in the whole genome. i.e. there are duoble or triple the number of chromosomes |
| What is Autoploidy | Is the multiplication of a genome with in the same species so the offspring receives 3 or 4 times the original haploid number. Often results in infertility |
| What is Alloploidy | Alloploidy is where gametes from two different species fuse to create a hybrid. These usually infertile. Results in changes in the numbers of sets of chromosomes between generations can lead to instant speciation through reproductive isolation. |
| Closely related species that live in the same geographical location | sympatric species |
| Closely related species that live in different geographical locations | Allopatric species |
| What are two types of reproductive isolation mechanisms | Pre-zygotic before egg formation and Post-zygotic after egg formation |
| Name some pre-zygotic isolating mechanisms | Geographical isolation, Structural isolation, Behavioral, temporal and ecological |
| What are some Geographical isolation mechanisms | mountains, rivers, lakes, oceans and desserts. |
| What are some Behavioural isolation mechanisms | Different courtship rituals, sexual selection and aggression between species |
| What are some Structual isolation mechanisms | The bits don't fit when they do it. i.e a horse trying to mate with a rabbit. |
| What are some ecological isolation mechanisms | Different habitats, populations rarely come into contact |
| What are some temporal isolation mechanisms | Different mating times and also different times of activity |
| What are the different types of post-zygotic isolating mechanisms | Hybrid invalidity, hybrid sterility and hybrid breakdown |
| What is hybrid invalidity | The embryo or zygote is in viable and so will die in early developement |
| What is hybrid sterility | The hybrid will survive to reproductive age but is sterile and cannot produce offspring, i.e. mules |
| Hybrid breakdown | The hybrid survives to a reproductive age and can produce offspring, however the next generation is usually sterile or cannot produce offspring |
| Describe how allopatric speciation can occur | Allopatric populations experience different environmental selection pressures and natural selection occurs and the two populations diverge and become genetically different. In order to become separate species reproductive isolation must occur in some way or another. Either postzygotic or prezygotic |
| When were the southern alps formed | 2 million years ago |
| When did New Zealand separate from Australasia | 80 million years ago |
| Glacial cycles have carved mountains and valleys over the past | 2.6 million years |
| What super continent did New Zealand belong to and when did it separate | Gondwana and It separated 70 million years ago |
| Explain how sympatric speciation occurs | A population in a varying environment with lots of intraspecific competition can occupy different niches within an environment to reduce competition and therefore adapt to a new niche within the environment. Instant specieation can also occur from polyploidy |
| Describe Gradualism | The gradual evolution of a species that results from natural selection and occurs over millions of years. The transition of one form to another in response to natural selection. |
| Explain punctuated equelibrium | Punctuated equilibrium is long periods of no change in evolution followed by sudden divergences with multiple species, little fossil evidence |
| What is divergence | Divergence is where two or more species evolve from a common ancestor, and typically occurs as a result of allopatric speciation where one population is geographically isolated from the other |
| Describe Adaptive radiation | Adaptive radiation is the sudden evolution of multiple species as a result of new niches becoming suddenly available in an environment. Species occupy new niches in order to reduce competition |
| What are homologous structures | Homologous structures are structures that are superficially different in look and function but have evolved from a common ancestral structure. i.e. the pentadactal forelimb |
| What are Analagous structures | Structures that superficially look similar, but have evolved from separate and unrelated ancestors as a result of similar selection pressures. |
| What is convergent evolution | Where two unrelated species evolve to look similar to each other, usually due to similar selection pressures |
| What is parallel evolution | Evolution of two closely related species along similar evolutionary lines independently |
| What is co-evolution | Co-evolution is the reciproical evolutionary change, where the change in evolution of one species, acts as a selection pressure to the evolution of the other species. e.g predator prey |
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