1 / 11

MICRO-EVOLUTION

MICRO-EVOLUTION. MECHANISMS OF EVOLUTION WITHIN POPULATIONS GENETIC DRIFT GENE FLOW MUTATION NON-RANDOM MATING NATURAL SELECTION. Micro-evolution: GENETIC DRIFT. FOUNDER PRINCIPLE e.g. Early Dutch Settlers in SA or new arrivals on isolated islands Small population (Founders)

hedley-hewitt
Download Presentation

MICRO-EVOLUTION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MICRO-EVOLUTION MECHANISMS OF EVOLUTION WITHIN POPULATIONS • GENETIC DRIFT • GENE FLOW • MUTATION • NON-RANDOM MATING • NATURAL SELECTION Annemarie Gebhardt 2008

  2. Micro-evolution: GENETIC DRIFT • FOUNDER PRINCIPLE • e.g. Early Dutch Settlers in SA or new arrivals on isolated islands • Small population (Founders) • Limited alleles in genome • Change in gene frequency • Some alleles become more prominent, e.g. • High cholesterol & porphyria • BOTTLENECK EFFECT • e.g. Cheetah populations in Africa and India • Chance events drastically reduced size of population • Loss of genetic diversity • Reduced genetic vigour • Inbreeding, disease prone, etc. Annemarie Gebhardt 2008

  3. GENE FLOW (Gene migration) • Migration of genes between populations • Closely related species or isolated populations mate / cross pollinate • Out breeding – resulting in hybrids • Fertile hybrids may evolve to new species • Common amongst SA Aloe species Annemarie Gebhardt 2008

  4. MUTATIONS • Random error in gene configuration • Environmental stress e.g. radiation, virus, extreme temperatures, chemicals, etc. • Somatic mutations – not inherited • Germline mutations may lead to speciation if new phenotype is advantageous • Main cause of polyploidy in plant species Annemarie Gebhardt 2008

  5. MUTATION TYPES LOCATION RESULTING NATURE LETHAL – both alleles thus homozygous – early death (foetus or young) NEUTRAL – no effect on next generation, until conditions change FIXED – advantageous to speciation (macro – evolution) • Chromosomal • DNA or in GENE(S) Caused by a single mutated gene ! Annemarie Gebhardt 2008

  6. GENE MUTATIONS Annemarie Gebhardt 2008

  7. NON-RANDOM BREEDING INBREEDING • Mating between relatives • Increases homozygosity • Harmful recessive genes become more prominent • May cause disorders e.g. • Haemophilia, Cystic fibroses, Muscular dystrophy, Hyper cholesterolemia ASSORTIVE BREEDING e.g. • Tall X Tall • Selecting mates with similar phenotypes Annemarie Gebhardt 2008

  8. NATURAL SELECTION • May cause rapid change in population characteristics e.g. in example below: • Some examples include the British Pepper moth; camouflage in animals; mimicry; pesticide- , antibiotics-, and antiviral resistance Annemarie Gebhardt 2008

  9. Natural Selection in Action Classic Pepper Moth Experiment Annemarie Gebhardt 2008

  10. ARTIFICIALSELECTION Annemarie Gebhardt 2008

  11. MISCONCEPTIONS Natural selection responds to a need Natural Selection = Evolution WRONG AGAIN ! WRONG !! Annemarie Gebhardt 2008

More Related