MICROEVOLUTION keywords - MICROEVOLUTION Allele one of two...

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MICROEVOLUTION Allele – one of two or more versions of a gene -different alleles can result in different observable phenotypic traits -each trait has 2 alleles -one allele/chrosome for diploid organisms -genetic variations in alleles can result in differences, also can be unnoticeable Allele frequencies: the abundance of one allele relatives to others at the same gene locus in individuals of a population -can be calculated by dividing the number of alleles for a certain trait/the total number of individuals in the population -usually expressed as proportion or a percentage -denoted as “p” or q” Allopatric speciation: a reproductive isolating mechanism that results from geographical separation between two populations -a prezygotic mechanism -caused by glaciers, continental shifts, etc Allopolyploidy: having 2 or more complete sets of chromosomes from different parent species -only plants are capable of this, not animals -results in a fertile hybrid
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-can be created from previously sterile species (ex bread wheat example) Autopolyploidy: having 2 or more complete sets of chromosomes from the same parent species -again only possible in plants through self fertilization -arise from a failure in the meiotic process -often resemble parents, except grow more slowly and flower later Behavioural Isolation: -a prezygotic isolation process -2 species do not mate because of differences in courtship behaviour -also known as ethological isolation -ex: songs of bullfrogs, fireflies example used in class (sequences of bursts of light vary for different speices of fireflies within males and females) Beneficial mutation: a mutation that proves to be beneficial for the individual; ex increases fitness -can help withstand diseases -ex: those who carry 1 allele of the sickle cell anemia disease are more resistant to malaria in areas of sub-saharan Africa Biological Species: the concept of a species based on the ability of populations to interbreed and produce fertile offspring -basically a reproductively isolated gene pool problems with the concept: how do you define a fossil species? how do you define populations that don’t reproduce asexually? (ex archaea and bacteria)
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Bottleneck Effect: occurs when an event, such as drought, or over-hunting causes a population to significantly dwindle in size -the survivors reproduce, but there is limited genetic variability -this is a problem! (can be solved by genetic drift) ex: elephant seals example Chromosomal Inversion: a chromosome rearrangement in which a segment of a chromosome is reversed end to end -occurs when a single chromosome undergoes breakage with itself -occurs in the arm of the chromosome, does not involve the centromere -do not usually cause abnormalities as long as the re-arrangement is balanced with no extra genetic info --however increased production of abnormal chromatids result in heterozygous individuals à lowered fertility due to production of unbalanced gametes Chromosomal translocation: rearrangement of parts between nonhomologous chromosomes
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