When Darwin published his
ideas on sexual selection, his emphasis was largely on birds, mammals and
insects (see graph below). Spiders continue to be a rather marginal group
in the study of sexual selection, but recent years have seen a steep increase
in papers. This review has three main parts:
First I focus on female choice
and male competition working in the various sensory modalities, with the
main conclusion that sexual selection in spiders may predominantly work
via channels of communication that are not as easily accessible to the
human observer as bird plumage, mammal weapons, and insect stridulation.
Then I consider some topics
for which spiders offer particularly useful model organisms, like sexual
size dimorphism, cannibalism, and sperm competition. The picture that is
emerging is a highly complex one, with seemingly homogenous characteristics
resulting from a variety of evolutionary and mechanistic causes.
Finally, this review presents
the current taxonomic status of the spider species cited by Darwin, and
shows that some of his examples appear better explained by natural than
by sexual selection.