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Lecture

Biol 121- 2010.03.22- Evolution- Sexual Selection, Definition of Species (Ch. 25-26).docx

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Department
Biology
Course
BIOL 121
Professor
Carol Pollock
Semester
Winter

Description
Biol 121 225 Freeman 520523 526531Mar 22 10 Evolution Sexual Selection What is a species What does natural selection favour traits with a fitness advantage What does sexual selection favour traits with a mating advantage leading to differential mating successindividuals have heritable traits that enhance their ability to obtain matestraits that attract members of the opposite sex are much more highlyelaborated in males sexual selection acts more strongly on malestherefore females invest much more in their offspring than do malestwo important consequences Two important consequences of the 1 Eggs are large and energetically expensive and thus females produce fundamental asymmetry of sex relatively few young during lifetime females fitness limited primarily by her ability to gain resources to produce more eggs and healthier youngnot by ability to find mate2 Sperm are so simply to produce that male can father an almost limitless number of offspring for males fitness is limited not by the ability to acquire the resources needed to produce sperm but by the number of females they can mate with Mating success the number of mates that produce offspring over a period of time Why is sexual reproduction so ensure that genes are passed on to offspring important 3 genetic variation prevent inbreedingresurgence of homozygous recessive alleles sexual dimorphism refers to any trait that differs between males and females size weapons males use to fight over females e
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