BIO152 Lecture November 15 2012—Why Sex?
These questions will help you to make the connection between what you read in your text book
and see in the film. Also remember this is testable material!!
During the film look for answers to the following questions:
1. Describe the example of asexually reproducing lizards in the US desert in the film? What
are the possible advantages to this group of animals to reproducing asexually?
- females give birth without having sex because it contains a complete set of the
mother’s genes, so each baby lizard is an exact clone of its mothers
- the lizards are able to “clone”
2. How does the experiment on minnows in Mexico show that sexual reproduction generates
more genetic diversity in a population than asexual reproduction?
- the asexually reproduced fish do not have genetic variability while thhe sexually
reproduced fish have enough variation to not necessarily be affected by sexual
3. What is the Red Queen hypothesis and how was it tested in the fish in Mexico?
- evolution is a race and does not stop (you have to run as fast as you can
- we are living in a complex world full of parasites, bacteria, etc all evolving. The
moment species stop evolving to these evolving challenges and threats, it’s doomed.
4. What are the main predictions of the sexual selection theory? What examples from the
film you have watched agree with these predictions?
- sex: best defence against rapidly evolving enemies (variability among offspring)
- the diversity of the offspring provide challeneges to parasites, competitors, etc.
- a female is much more choosy about who she combines with because she doesn’t
produce as many eggs as males produce sperm. Thus males aren’t that choosy about
who they combine with because they produce a lot of sperm.
5. In what situation would you expect competition among males to become the primary
cause of sexual selection?
6. Using the information given in the film, explain how the gender role reversal in jacanas is
an evolutionary strategy for survival?
- the female lays the eggs but it’s the male who keeps them warm and raises the chicks
- the females care more about quantity as opposed toquality, and have developed male
- male and female roles are not set in stone: they’re determined by which sex competes
for mates and which sex nurturs their young
7. In the film, Dr Marion Petrie demonstrated that peahens preferred to mate with peacocks
with long flashy tails. In the other part of the experiment she paired females with males of
varied tail lengths. How did this experiment test the central assumption of the sexual
selection theory as