kuento@kuhub.cc.ukans.edu (11/03/90)
Here is a problem in population biology that - as far as I have been
able to discern - has never been described or analyzed for any type
of organism (and in the present case, it is crucial to an
understanding of the evolution of social behavior).
I study Sweat Bees (family Halictidae), many of which are primitively
social to varying degrees. My research has led me to conclude that
what determines "caste" (nest-founding females vs. "workers") is
whether or not a female mates when she is one or two days old. In
other words, caste is determined after adulthood is reached, and males
must be present for females to become future reproductives (gynes).
Sweat bees, of course, determine the sex of the eggs they lay, so it
is essential to the maintenance of sociality that they produce some
females before they produce their first males (if males emerge first,
or in large relative numbers, they will mate with the young females
and there will be no workers). Do you start to see the problems here?
How can one ever talk about sex ratio theory when (a) it becomes so
intertwined with sociality, and (b) not simply the *number* of males,
but also their time of emergence, dictates how many *FUNCTIONAL*
females are produced? For a mother sweat bee, it is a matter of
chance whether any given female egg she lays will result in a true
female (a gyne), or a partially-reproductive one (a worker - which
can lay occasional male eggs, sometimes female eggs, under the right
circumstances). It's hard enough to define the sex ratio when you
have two such classes of females, but to treat it as an evolutionary
problem becomes immensely complex. To make matters worse, it looks as
if male production is tied in to temperature and photoperiod, so in
cool springs, or years where nesting begins earlier in the season,
there are relatively more females produced early, and thus more of the
population is social (a higher percentage of workers), and the reverse
is true in years with warm springs or late nest initiation (more
males, fewer workers, and more non-social nests).
Are there ANY theories/models out there that are directly
applicable, or must I (as I've long suspected) generate a whole new
set of theories of my own to specifically deal with the intricacies
of this unique natural history? I'm open to suggestions/discussion.
----------------------------------------------------------------
Doug Yanega (Snow Museum, Univ. of KS, Lawrence, KS 66045)
My card: 0 The Fool "UT!" Bitnet: Beeman@ukanvm
"This is my theory, such as it is....which is mine. AAH-HEM!"