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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, where
fewer 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