Descent with modification A Darwinian View of Life 1 Biology 1202 unit 1 Chapter 22 Evolution 1 Change over time of genetic composition of a pop 2 Descent of modern organisms with modification form pre existing organisms Accumulation of inherited characteristics that enhance organisms ability to survive in Evolutionary adaptation specific environments Pre Darwinian Theory of Evolution 1 Lamarck giraffe example a Use and disuse i Bodies of living organisms are modified through use disuse of parts Inheritance of acquired characteristics b c Wrong ideas Evolution by Natural Selection Darwin and Wallace came up with this idea independently o Darwin voyage of the Beagle o Wallace naturalist in Indonesia Natural selection o Survival of the fittest o Process selects from what is available in the gene pool o New characteristics not created on demand Mechanism behind natural selection 1 Variability 2 Heritability 3 Differential reproductive success Observations o Vary in their heritable characteristics o Produce more offspring than the env can handle Inferences o Well suited org produce more offspring o Over time favorable traits accumulate in pop Race example Winners do it losers die Artificial Selection analogous to natural selection Selective breeding Ex breeding dogs Evolution is supported by overwhelming amounts of evidence 2 Biology 1202 unit 1 Resistant strains of bacteria HIV survive Increase frequency of pop Homologous and Analogous Structures 1 Homologous Structures attributes resembling each other bc of common ancestry Ex mammalian forelimbs Ex vertebrate embryos o Share similar developmental genes o Differences arise when certain genes are switched on off Biochemistry and molecular biology o DNA universal genetic material o 20 amino acids protein o ATP energy o RNA ribosomes protein 2 Analogous Structures attributes similar in function Trees vs Scala Naturae Homologies and Tree thinking Convergent Evolution Similarity b w 2 things due to independent evolution along similar lines rather than descent from a common ancestor Chapter 23 Evolution of Populations Smallest unit of evolution Common misconception individuals evolve Populations evolve but evolutionary processes act on individuals Genetic variation makes evolution possible Mutation changes in nucleotide sequence of DNA new alleles and genes o Point mutation change nucleotide base in a gene o Chromosomal mutation delete disrupt rearrange loci on a chromosome o Gene duplications duplications of whole segments of a chromosome o Mutation rate 1 100 000 genes per generation Sexual recombination o Produce most variability 1 Crossing over during Prophase I 2 Independent assortment during Metaphase I Biology 1202 unit 1 Variation within a population 1 Discrete characteristics a Classified on an either or basis b Ex Flower color in pea plants 2 Quantitative characteristics a Vary along a continuum within a population b Ex Height weight The Hardy Weinberg equation can be used to test whether a population is evolving 3
View Full Document
Unlocking...