Sexual Selection

Peacock Video

It's not an elk. It's actually the largest deer ever described.

The species disappeared about 10,000 years ago.

The antlers span 12 feet from tip to tip.

They weigh about 90 pounds.

90 pound rack on a 5 pound skull.

Males had to regrow these every year.

The courtship call of male Tungara frogs attracts both

females and predators

http://www.sbs.utexas.edu/ryan/Multimedia/tungara%20coompl%20series.wav

Why do males have such costly traits when females lack them?

Why sexual reproduction at all?

The Guinness Book of World Records gives the "official" record number of children for a woman as 69, produced by an 18th century Russian peasant.

In 27 pregnancies between 1725 and 1745, she had 16 pairs of twins, 7 sets of triplets, and 4 sets of quadruplets.

She presumably had some physiological or genetic predisposition to multiple births.

But this is nothing compared to the record for men.

Mulai Ismail (1646-1727), an emperor of Morocco, was reported as having father "at least 342 daughters and 525 sons."

Female Maximum = 69, Male Maximum = 867

e.g. elephant seals, wherefewer than 20% of the males obtain a mate

Interpret the graph.A) Males have more weaned pups than females;B) Females have more weaned pups than males;C) Most females do not wean pups;D) Most males do not wean pups.

Issues:

1) Sperm are unlimited?

2) Should compare how many gametes are required to achieve fertilization, rather than single gamete

3) Insemination does not = fertilization

Another crazy thing . . .

A pair of red phalaropes on their breeding grounds in Alaskan tundra

Female Male

Phalaropes

Females are larger and more brightly colored than males.

The females pursue and fight over males, then defend them from other females until the male begins incubation of the clutch.

Males perform all incubation and chick care, while the female attempts to find another male to mate with.

If a male loses his eggs to predation, he will often repair with his original mate or a new female, who will lay another clutch.

In the Deep-Snouted Pipefish, males become pregnant.

Females attach their eggs to the male.

Females have 2X as many eggs as males have room for in their pouches.

Females compete.

Males choose.

Sometimes, females get a direct benefit of mating, e.g. nuptial gift in hangingflies

Videos

Bower Birds