The Biology of Love *
*Please note. This discussion in no way attempts to discuss love in a religious
context. Rather it is merely an entertaining way to learn about the sometimes
comical world of biological reproduction.

If not for sex[ual reproduction], much of what is
flamboyant and beautiful in nature would not exist.
–Olivia Judson

Lucky in Love
Sexual reproduction is like the best strategy for winning the lottery
Increasing variety increases species chances for success

Red Queen Hypothesis
Sexual reproduction can create variation
from generation to generation evolved
to allow species to develop adaptations
to avoid their specific parasites.
\"It takes all the running you can do, to keep in the same place.\"
Mutational Deterministic Hypothesis
As generations pass, the mutations act upon
one another in an exponentially harmful build-
up that finally works to kill the organism,
killing the mutations in the process.

So Many Choices When Choosing a
Mate
Monogamy vs. Polygamy
Monogamy (my heart beats only for you!)
Some advantages of monogamy…
•geographic distribution of mates
•incidence of parasites and sexually transmitted
diseases
•amount of parental care given to offspring
•mate guarding behaviors
•infanticide
•length of breeding season
•chemical mechanisms of bonding in the brain

Polygamy
….I love you and you and you and you and you
Females are more selective, males less picky! Why?
The duration of relationship depends on several factors:
-do offspring need a lot of parental care?
-does the male have a right to question paternity?

Who’s going to watch the kids?
Parental care vs. No Parental Care
Make the choice that, in your environment, will lead to the
greatest number of successful offspring!

oney, how many kids should we have? 4 or 400
Big-bang Reproduction or Repeated Reproduction
Again, the choice depends on the environment and the survival
rate of the offspring.

en there’s not enough males around, never f
et a sex change! And still produce offsprin
To some species, a combination of genetic and environmental
factors determine sex.

I’ve had enough of this!
I’m going to do my own thing!
Give up on sexual reproduction and become asexual!

Really Fun Methods of
Reproduction in the Natural
World
It’s better to have loved and lost, then to have never loved at all!
Sexual Suicide.
Males that die during or soon after copulation, but their
mate often dines on their lifeless body.

Male Gender Inequity and Exploitation.
Males have greatly reduced body size and anatomy, and limited
life experiences compared with the female--often dying within
hours after copulation or persisting as a tiny blood-sucking
parasite attached to the female's body.

Arguably the most
exquisitely evolved mating
behaviors belong to the
Class Aves (birds)