Textbook Notes (368,432)
Canada (161,877)
BIOA01H3 (202)
Chapter 17

BIOA01- Chapter 17 Textbook notes combined with lecture notes with images from lecture powerpoints. Some abbreviations I might have used: pop = population. Evol= evolution.

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Biological Sciences
Mary Olaveson

Ch 17 Microevolution Genetic changes within populations 171 Variation in Natural Populations Pg 374 y Microevolution heritable change in the genetics of a population o change in the genetic makeup of a population from generation to generation due to natural Selection o leads to variation in genetic makeup of population over time y Populationgroup of individualsbelonging to the same species living at the same time and in the same areaindividualscaninteract y a new era of biology began in 1859 when Charles Darwin published On the Origin of Species by Means of Natural Selectiono focused biologists attention on great diversity of organismsmajor points o Darwin made two presented evidence that presentday species are descendants of ancestral species that were different o proposed a mechanism for evolutionary processesNaturalSelection y DifferentialSurvivalinNature NaturalSelection o populations in nature do notgrow exponentially indefinitely o reach a stable level carrying capacity determined by limiting resourceso leads to struggle for existence o only a portion of offspring survive and reproduce o mostoffspringdie 80 is typical in wild populationsy Variation differences between individuals in a population y Heredity somevariationsarepassedon tooffspringoindividualswithsomevariations survivebetter than others with none o traits that increase survival are passed on tooffspring y Resultdifferential ability to survive and reproduce will lead togradual change in populationwith accumulation of favourable traits selected over generations by naturey Favourabletraits that survive lead to genetic variation among individuals in populationscontribute to evolution of species y common misconception about evolution is that individual organisms evolve during their lifetimesbut populations evolve y Natural Selection acts on individualsy Phenotypic variation differences in appearance or function that are passed from generation to generation y evolutionary biologists describe and quantify phenotypic variationdue to o heritable variation in appearance andor functiongeneticcause mutations recombination through crossing over independent assortment and random fertilization o phenotypic plasticity environmentalcause the ability of an organism to change its phenotype in response to changes in the environment y Quantitative variation individuals differ in small incremental ways o Characteristics with a range of variation o Controlled by multiple genes yy Qualitative variation they exist in two or more discrete states and intermediate forms are often absent o Characteristics with distinct states o Polymorphism distinct variants of characterThe occurrence of something in different forms in particular o Describe by percentage or frequency of each y Causes of phenotypic variation o Genetic differences between individuals o Diff in env Factors that individuals experience o Interaction between genetics and the environment y Genetic and phenotypic variations may not be perfectly correlated y Diff genotypes can have the same phenotype y Same genotype can have diff phenotype Eg acidity of soil changes flower color y Only genetically based variation is subject to evolutionary change
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