BIOL 112 1nd Edition Lecture 9 Outline of Last Lecture I Exam prep II Natural selection revisited III Important notes about NS IV Sexual selection NS for mating V Sexual selection a tradeof VI How genetic variation is maintained Outline of Current Lecture VII Microevolution VIII What is a species Current Lecture o 2 Balancing selection Heterozygous advantage ex Sickle cell anemia in areas with malaria Heterozygote fitness homozygote fitness Sickle cell allele recessive mutation in hemoglobin Hb If Hbw Hbsickle red blood cells get destroyed regularly in the liner along with malaria HbS HbS is lethal but HbW HbW is vulnerable to malaria So in areas with malaria HbS frequency is greater than in areas without malaria Fig 23 17 Frequency dependent solution Frequency of a phenotype becomes less common if theirs too high of a frequency of that phenotype Scale eating fish left oriented and right oriented o Attack prey from left or right o Frequency of left vs right alternated over time o Prey avoid common allele phenotypes uncommon then increase in frequency due to greater success Microevolution o Species smallest taxonomic unit What is a species o Many definitions species concepts 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 o 1 Morphological Used by Linnaeus Organisms that have similar morphology a species Limitation incorrectly group tow similar looking species OR put variants of the same species 2 diferent species o 2 Biological species concept BSC Species interbreeding population Genetically isolated from other groups No gene flow between diferent species Two levels of barriers that prevent 2 species from interbreeding Pre zygotic o Habitat isolation o Temporal isolation diferent mating behaviors o Mechanical isolation incompatible mating structures o Gametic isolation gametes are incompatible fail to fuze into a zygote Post zygotic zygote is made but o Reduced hybrid viability zygote hybrid progeny but it dies or is feeble o Reduced hybrid fertility hybrid is robust but is sterile o Hybrid breakdown eventual breakdown of hybrid over several generations
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