Recipes for LOVIN’ Some why’s and how’s of animals gettin’ it on….. Some why’s and how’s of animals gettin’ it on….. By: Demetri Kollias, Andrea Rangel, Mussie Yonas, Yevgeniy Maksimenko. By: Demetri Kollias, Andrea Rangel, Mussie Yonas, Yevgeniy Maksimenko.

 Warning!  Recipes for lovin’ is about: Recipes for lovin’ is about: Post-copulatory male and male\female competitionPost-copulatory male and male\female competition Protein evolution in the origin of new speciesProtein evolution in the origin of new species HomosexualityHomosexuality Disclaimer: Some of the material about to be viewed is of a sensitive nature and strictly hypothetical.

Male-female competition Male tricks to keep their female to themselves only via chemicals. Male tricks to keep their female to themselves only via chemicals. To turn off her sex drive. To turn off her sex drive. To make her lay more eggs right after sex. To make her lay more eggs right after sex. (Judson et al, 2002)

Male-male competition Chemical used to dissolve previous stored sperm in the female Chemical used to dissolve previous stored sperm in the female Chemicals that makes the female stinky. Chemicals that makes the female stinky. Chemicals that makes the female aggressive to other males. Chemicals that makes the female aggressive to other males. (Judson et al, 2002)

Hermaphrodite Garden snails use love dart. Garden snails use love dart. (Barker et al, 2001)

Deer roaring Brings females to heat much sooner. (Judson et al, 2002)

Battle of sexes may lead to formation of new species Proteins that involved in reproduction Proteins that involved in reproduction Affinity lead to evolution of proteins Affinity lead to evolution of proteins Battle of sexes Battle of sexes protein evolution new species (Levinton et al, 2001)

Proteins “Species is a group of organisms that can interbreed.” “Species is a group of organisms that can interbreed.” Proteins that are involved in reproduction are fundamental to the identity of some species. Proteins that are involved in reproduction are fundamental to the identity of some species. (Levinton et al, 2001)

Proteins Bindin Bindin Shape of the protein Shape of the protein (Levinton et al, 2001)

Affinity to a specific protein Physical Separation Reproductive incompatibilities (Campbell et al, 2002)

Battle of sexes and new species Abalone Abalone Lysin and egg envelope Lysin and egg envelope VERL and its mutation VERL and its mutation (Levinton et al, 2001)

Why is homosexuality still around?

1. The pleasure principle 1. The pleasure principle (Weber et al, 1982)

2. Social Functions 2. Social Functions Aggression + Dominance Intimacy Teamwork (Burg et al, 2002) (Judson et al, 2002)

3. Desperation 3. Desperation Short span of sexual maturity Scarcity of mates (Judson et al, 2002)

Assuming that homosexuality is genetic, why is it still in the gene pool? Assuming that homosexuality is genetic, why is it still in the gene pool? Evolutionarily speaking, homosexuality is bewildering Evolutionarily speaking, homosexuality is bewildering IF AND ONLY IF...

3 conditions are met: 1. Behavior must have a genetic basis 1. Behavior must have a genetic basis Natural Selection

2. It must be exclusive 2. It must be exclusive No reproduction

3. Homosexuals must make up a significant portion of the population 3. Homosexuals must make up a significant portion of the population But....

None of these are met! (Judson et al, 2002) Genetically Exclusivity Incidence

Assuming all the conditions were met, How can these genes be maintained in a population? How can these genes be maintained in a population? Altruism (Zuk et al, 2003)

Suppression (Glover et al, 1999)

Heterozygote advantage Heterozygote advantage (Campbell et al, 2002)

Battle of the sexes! Battle of the sexes! So how can genes for homosexuality be favored by natural selection? fruit fly studies Drosophila melanogaster Genes which cause advantages to females may also cause disadvantages to males. (Judson et al, 2002)

Lovin’ recipes call for: The battle of the sexes is the key ingredient. The battle of the sexes is the key ingredient. CompetitionCompetition Protein evolutionProtein evolution HomosexualityHomosexuality

The End

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