BIOL 1107 1nd Edition Lecture 35 Outline of Last Lecture I Hardy Weinberg II Non random mating III Changes in allele frequency definitions Outline of Current Lecture I Populations and Change II Variations III Pre zygotic and Post zygotic Mechanisms IV Speciation Current Lecture I Populations and Change II What can cause populations to change Selective breeding common ancestor Ex mustard seeds a b and c o Take place with dogs as well Chickens with large breasts and cows that produce more milk selectively bred Change requires variation Variations Mutations from replication errors Meiosis new allele combinations o Independent assortment causes large variations in of gametes Fertilization of the egg Variation is important for the species as a whole Preserving variation o Ex people resistant to bubonic plague are resistant to HIV o Speciation as a result of natural selection What are species o Viceroy vs Monarch buttery which is poisonous two different species Viceroy mimics Monarch so that it doesn t get eaten These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III o Bluebirds same species see pic on elc New male blue vs female dull color Biological species concept bases species on its ability to reproduce fertile offspring Pre zygotic and Post zygotic Mechanisms Pre zygotic mechanisms o They stop species from interbreeding o One of the biggest barriers from speciation separation geographic barriers o Habitat isolation lion grassy areas vs tiger jungle areas o Gametic isolation egg and sperm just not compatible IV Post zygotic mechanisms o Hybrid invariability o Hybrid sterility horse donkey mule sterile Horse has 32 pairs of chromosomes donkey has 31 and mule has 30 pairs and 3 single chromosomes Mules formation of gametes cannot occur meiosis cannot take place Speciation Allopatric ex squirrels lizards populations are geographically separated Sympatric habitat differences lion vs tiger tree beetle vs ground beetle sexual selection appearance of mate How quickly does speciation occur Two competing hypotheses
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