Microevolution and speciation Keywords

Microevolution and speciation Keywords - Microevolution and...

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Microevolution and Speciation Term Definition Key Points Allele One of two versions of a gene Allele frequencies The abundance of one allele relative to others at the same gene locus in individuals of a population Allopatric Speciation The evolution of reproductive isolating mechanisms between two populations that are geographically separated Large species gets divided, example by a river Populations evolve independently and diverge into different species Species later do not interbreed Allopolyploidy The genetic condition of having two or more complete sets of chromosomes from different parent species 2n=6 spontaneously doubles during mitosis creating 2n=12 , this instantly creates sets of homologous chromosomes. Self-fertilization can then generate polyploid individuals that are reproductively isolated from both parent species Autopolypoloidy The genetic condition of having more than two sets of chromosomes from the same parent species A spontaneous doubling of chromosomes during meiosis produces diploid gametes. If the plant fertilizes itself, a tetraploid zygote will be produced Behavioral isolation A prezygotic reproductive isolating mechanism in which two species do not mate because of differences in courtship behavior; also known as ethological isolation Behavioral signals not recognized by female Example: fireflies Beneficial Mutation
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Biological species Group of species that can successfully interbreed and produce fertile offspring Bottleneck effect A reduced amount of variation in a population Large population dies Can be caused by disease, starvation, droughts, etc Even if the population returns to its original size, the variation is greatly reduced Chromosomal Inversion Chromosomal translocation Crossing over The recombination process in meiosis, in which chromatids exchange segments Deleterious mutation Diploid An organism or cell with two copies of each type of chromosome in its nucleus Directional selection A type of selection in which individuals near one end of the phenotypic spectrum have the highest relative fitness Shifts a trait away from the existing mean and towards the favoured extreme Example: the birds that like the long tails Disruptive selection A type of natural selection in which extreme phenotypes have higher relative fitness than intermediate phenotypes Mean phenotype is not favoured Both extremes are favoured Example: Female birds that like both small and large tails but not average Can lead to speciation Dominant Allele The allele expressed when more than one allele is present
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Ecological isolation A prezygotic reproductive isolating mechanism in which species that live in the same geographic region occupy different habitats Live in different habitats Separated by a factor of the environment They are in different ecologies Ecological Species A group of organisms that share a distinct ecological niche Female choice Fitness Number of surviving
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Microevolution and speciation Keywords - Microevolution and...

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