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Microevolution & Speciation - Key Words

Microevolution & Speciation - Key Words -...

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M ICROEVOLUTION & S PECIATION K EY W ORDS - Allele o PAIR (or series) of different forms of a gene o CAN occupy the same location on a particular chromosome + control the same character o Types Phentoype – expressed trait Genotype – genetic construction of trait - Allele Frequencies o How COMMON a certain allelle is in a population o Use: describe GENETIC DIVERSITY - Allopatric Speciation (Vicariance, relates to biogeography) o Origin of 2 or more species resulting from divergent evolution of populations that are geographically isolated from each other o Detailed Organisms ranges are ENTIRELY separate, DO NOT occur in ANY one place together Populations PHYSICALLY isolated by extrinsic barrier Evolve / reproduce intrinsically in isolation Creates 2 species that are similar, BUT one is a CHANGED version of the other - Allopolyploidy (form of polypoidy) o more of than the usual number of chromosomes, x > 2n o results from the interbreeding of different species - Autopolypoloidy (form of polypoidy) o More than 2 sets of chromosomes, x > 2n o Derived from the same specie o Results from redoubling - Biological Species (taxonomy = kingdom/phylum/class/order/family/genus/specie) NO universal agreement for WHAT it is LIVING animal OR plant E.g. – Canola vs. Rapeseed E.g. – Hemp vs. Marijuana Known Quantities 1.3 – 1.5 (mi) named to date (about 1/10 th ) of total 10:1 error ratio b/c others = NOT seen 900 000 insects - Bottleneck Effect (Hardy-Weinberg Principles – genetic drift) FORM of gene drift VARIABILITY in genes = ↓
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Population = DRASTICALLY reduced in size DUE TO intense selection pressure OR natural calamity E.g. – Tomato (Taste) E.g. – Crops (can’t survive w/o pesticides) - Chromosomal Mutation CHANGE genetic structure Types Inversion o Repair is BACWARDS O USUALLY do NOT cause abnormalities, AS LONG as NO missing / extra information o CAN be placed in FRONT of regulatory regions, causes CHANGE in function o Types Paracentric – DO NOT include centromere, BOTH breaks in ONE arm of chromosome Pericentric – INCLUDE centromere, breaks in EACH arm Translocation o Rearrangment between parts of NON-HOMOLOUS chromosomes o Change where MAJOR regions are exchanged E.g. – Leukemia genes Gene Duplication O ANY duplication of a region of DNA that contains a GENE o Primary copy = USED o Secondary copy = FREE from selective pressure NO deleterious effect o Mutates FASTER than a functional single-copy gene b/c 2x! Polyploidy o X > 2 sets of paired chromosomes E.g. – Plants, Goldfish - Chromosomal Crossing Over CREATES NEW gene combinations Codes for SAME thing E.g. – meiosis - Diploid 2n NORMAL amount of DNA / cell 2 sets of chromosomes OR 2x haploid # of chromosomes E.g. – Humans, MOST animals - Directional Selection Natural Selection = FAVOURS a SINGLE genotype ONE trait is “chosen” to be passed on (“Successful trait”) Amount of individuals with THAT trait ↑
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