The fourth in a series from the blog Gender and Sexuality in Nature, a 2016 UC Davis course organized by UM EEB alumnus Ash Zemenick (UM EEB B.S. 2011, Ph.D. UC Davis 2017) and Jacob Moore (B.S. University of Washington 2009, Ph.D. UC Davis 2017).
In species where anisogamy occurs, the sexes are defined by gamete size. Those individuals with large gametes, called eggs, are defined to be females; while those individuals with small gametes (sperm) are defined to be males. But differences between males and females extend beyond gamete size – there are differences in behavior and appearance too. For example, one sex (typically males) may have beautiful ornaments or fierce armaments that are thought to aid in competition for mates. The other sex may not have these ornaments or armaments (typically females), and instead of competing, they usually choose among potential suitors and provide the bulk of parental care to the young. This process of male competition and female choosiness is known as sexual selection.
For materials and information on teaching sex- and gender-related topics in biology see www.projectbiodiversify.org/sex
Reposted with permission with the caveat that these posts are several years old and Project Biodiversify and other efforts like Gender Inclusive Biology and other LBGTQIA2+ people are always working to improve and update.