Dr. Tatiana’s Dr. Tatiana’s Gilbert the Peacock Gilbert the Peacock

And And FriendsFriends

SexSex AdviceAdvice

Gilbert the Gilbert the PeacockPeacock

Dear Dr. Tatiana,Dear Dr. Tatiana,I have a lousy tail. It’s I have a lousy tail. It’s not colorful, my not colorful, my eyespots are pathetic, eyespots are pathetic, and hens don’t even and hens don’t even notice me when I put it notice me when I put it up. What should I do?up. What should I do?

- Gilbert the - Gilbert the

PeacockPeacock

Dr. Tatiana’s Dr. Tatiana’s AdviceAdvice

Join A Gang … Like Your FriendsJoin A Gang … Like Your Friends

• Bluehead Wrasse (Coral Reef Fish)

• Males team up to chase a large male from territory• Female arrives… all young males spawn her

Dr. Tatiana’s Dr. Tatiana’s AdviceAdvice

Join a Gang … Like Your Friends

• Sea Lions • Biggest male guards harems and chases young males away• Groups will rush the beach, break up harems, and mate with females

Group resting after a successful rush

Gilbert’s SolutionGilbert’s SolutionJoin a Lek (group of peacocks)

• Female peacocks want nothing from males but their sperm• Leks are organized so females can choose who they want to have sex with• Doesn’t cost her anything, tough on males

Gilbert’s FriendsGilbert’s FriendsWhat some females find sexy…• Cyrtocara Eucisnostomus (specific fish)

• Males judged on tallest sandcastles•Takes nearly two weeks to build

* Fish grows to about four inches, while tallest sandcastles can be built as long as

40 inches (underwater)

Gilbert’s FriendsGilbert’s FriendsWhat some females find sexy…• Hammer Headed Bat (West Africa) • Females

prefer bats who can honk loudest•During breeding season, males honk for hours to get attention

* Voice box occupies more than half the body cavity

So Why A Lek?So Why A Lek?1st Reason

• Females are attracted to groups rather than males all by themselves• The larger the lek, the more attractive to the female (so size matters)• Peacock leks have room for those who lack sex appeal (so Gilbert has a chance)

So Why A Lek?So Why A Lek?2nd Reason

• Find brothers and half brothers to lek with• Even if Gilbert never finds a mate, he helps attract mates by being there (taking one for the team)• Since Gilbert and his brothers share genes, he passes on his genes by helping them pass on theirs

Peacock Peacock BrotherhoodBrotherhood

• Peacock brotherhood recognizes it own when forming leks• Secret Society for peacocks

Gilbert’s Lek

Fraternal Fraternal CooperationCooperation

Lions are most famous example of fraternal cooperation• Lionesses live in family

groups and rear cubs in joint litters (lucky males)• Larger coalition of lions, longer they hold on to a pride • More male cubs = longer future for coalitions

Fraternal Fraternal CooperationCooperation

Lionesses have evolved…

• When a female gives birth to a large litter, there are typically more males born• When several females give birth in a pride simultaneously, cubs predominately male

Lion CoalitionLion Coalition

Circle of Life

THE ENDTHE END