Evolution Biology Unit 3

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Terms in this set (25)
AlleleAn alternative form of a gene.Adaptations arethe way in which organisms are ideally shaped to enhance their survival in specific environments. Ex- The way the finch's beak changed shape depending on which Galapagos Island the bird was from and what type of food was there.4 principals of Natural Selection1) Variations of Phenotypes 2)Variations are heritable and can be passed on to offspring 3)Struggle for existence (more population than resources) 4)Survival and reproductive RatesPhenotypeAn organism's physical appearance, or visible traits.GenotypeAn organism's genetic makeup, or allele combinations.Modes of Selectiondirectional, stabilizing, disruptive, sexual, artificial and naturaldirectional selectionoccurs when natural selection favors one of the extreme variations of a trait (ex-peppered moth)stabalizing selectionselection that favors average version of that trait (Ex- human birth weight...usually in the middle of the range because babies too small do not survive and babies too large cannot be birthed naturally)disruptive selectionfavors individuals at both extremes of the phenotypic rangesexual selectionwhen individuals select mates based on heritable traits (peacock) or when there is a competition between males for females (usually the strongest one wins, to make a stronger off spring)artifical selectionthe selective breeding of organisms by humans for specific characteristics (Ex- all dogs are from the wolf but we breed specific traits to make some Corgis and others Grey Hounds)natural selectionA natural process resulting in the evolution of organisms best adapted to the environment.decent with modificationThe principle that each living species has descended, with changes, from other species over time. When animals have babies, those babies look and act slightly different from their parents and their siblings. This is due to random genetic mutations.common descentprinciple that all living things were derived from common ancestorsantibiotic resistant bacteriabacteria that undergo mutation to become resistant to an antibiotic and then survive to increase in number. (Ex- MRSA, VRE) to help control this, only take antibiotics for Bacterial infections, NOT VIRAL.