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Definition
| Inherited feature that enables memebers of a species to live and repoduce in a habitat |
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Definition
| A form of divergent evolution in which there is a rapid proliferation of forms from an ancestral type because of the sudden availability of niches |
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| The proportion of a particular form of a gene in a gene pool |
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Definition
| Speciation occuring where organisms are initially capable of interbreeding but cannot because they are geographically seperated |
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| Structures that are superficially similar but have evolved in different ways e.g. wings on birds, bats and insects |
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| Gene pool based on the genes of a few survivors |
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Definition
| A gradual variation in the characteristic of a species or population over its geographical range |
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| The development of superficially simular structures and unrelated organisms, usually because the organisms live in the same kind of environment |
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Definition
| Natural selection against one end of a range of variation resulting in a progressive change in allele frequency |
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| Natural selection acting against the middle of a range variation (favouring both of the extremes) |
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Definition
| The type of evolution where a common ancestor devides in to two or more lines dissimular characteristics due to the enviroments they live in |
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Definition
| Individuals leaving the population to join another (this decreases the genetic variation) |
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| Emigration and Genetic Drift. |
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Definition
| Two ways of decreasing genetic variety |
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Definition
| Found only in that country |
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Definition
| The gradual process by which the present diversity of plants and animals arose from the earliest and most primitive organisms |
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Definition
| A chance change in allele frequency which occurs when a small group of individuals become detached from the main population |
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Definition
| Exchange of genes between populations |
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Definition
| The proportions of a particular gene in a gene pool |
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Definition
| All the genes of all members of a population and their alleles |
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Definition
| The change in allele fequencies of a population as a result of chance process |
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Definition
| When the gene frequencies in a population are staying the same from generation to generation |
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Definition
| A physical barrier preventing breeding between different groups of the same species that can often lead to evolution e.g. new bodies of water forming |
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Definition
| Fossils preserved in sedimentary rock layers that can be used to trace the evolutionary history of a species |
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Definition
| Evolution proceeds slowly but continuously. Eventually the accumulated changes result in speciation |
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Definition
| Structures that have similar evolutionary history but have developed to suit different functions e.g. wings, flippers and arms |
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Definition
| A zygote forms but does not develop properly |
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Definition
| A hybrid forms but is sterile e.g. a mule |
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Definition
| The hybrid offspring are fertile but produce infertile offspring |
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Definition
| New individuals entering the population (this gives the population more genetic variation) |
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Definition
| The seperation of one pair of allels does not affect the seperation of another pair of alleles |
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Definition
| Formation of a new species through pollyploidy because the chromosome numbers of new "instant" species do not match that of the original species. They cannot interbreed |
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Definition
| The formation of a completely new species, genus etc |
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Definition
| Sexual selection e.g. hens choosing roosters with larger tail feathers |
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Definition
| The accumulation of new characteristics in a species through mutation |
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Definition
| Two ways of increasing genetic variety |
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Definition
| The process that brings about new species by the elimination of the less adapted individuals and the survival of the organisms which are better adapted |
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Definition
| The development of related organisms along similar evolutionary paths due to strong selective pressures acting on all of them in the same way |
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Definition
| Mutation producing more than twice the normal haploid number of chromosomes |
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Definition
| All the members of the same species of different ages in the same time and place |
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Definition
| Isolating mechanism that acts after fertilization to prevent the exchange of genes between populations by imparing the development or fertility of the offspring |
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Definition
| Isolating mechanism that acts to prevent the fusion of gametes from different populations |
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Term
| Prezygotic and Postzygotic |
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Definition
| Two types of reproductive barriers |
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Definition
| There are long periods of little evolutionary change interupted by short bursts of rapid speciation |
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Definition
| Gene mixing to give new combinations of existing genes caused by meiosis and fertilisation |
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Definition
| A barrier to breeding that exists due to the difference in mating seasons or mating organs |
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Definition
| Two apparently distinct species that are connected by a series of intermediate geographical and structual subspecies between which interbreeding can occur e.g. a chihuahua and a great dane cannot breed naturally due to size difference however they can both breed with a poodle |
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Definition
| The strength of natural selection |
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Definition
| Development of one or more species from an existing species, when populations diverge so much from the parent population that interbreeding cannot occur |
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Definition
| A group of organisms that normally interbreed in nature to produce fertile offspring and belong to the same gene pool |
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Definition
| Natural selection that restricts variation in a population |
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Definition
| Speciation occuring where organisms living in the same area are in theory capable of interbreading but cannot because of differences in behaviour e.g. mating call or flowering time |
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Definition
| Any part of an organism that has deminished over time because the function it serves has decreased in importance e.g. the wings on the Kiwi |
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