From: xgl (xli03@emory.edu)
Date: Mon Jan 08 2001 - 12:35:25 MST
okay, i've got _sociobiology_ on my lap. below are some passages
from wilson's discussion of hamiltonian kin selection in the order
hymenoptera (wasps, bees, ants, etc.).
-x
-------------------------------------------------------------------------------
[Chapter 20, The Social Insects]
[The Prime Movers of Higher Social Evolution in Insects]
"This strange calculus, when extended to other kin (see Table
20-3), leads to even stranger conclusions. Consider, for example, the
prediction that males should be more consistently selfish than females
toward everyone else in the colony. This is expected to be the case
because under all conditions except complete queen domination of the
workers, a male's expected reproductive success is greater than that of a
similar sized female (see below). In order for selection to favor male
altruism, such altruism would have to confer greater benefits than similar
altruism by a female -- an unlikely situation. Not only is this
prediction met in nature, its fulfillment seems explicable only by this
particular theory. The selfishness of male behavior is well know but has
never before been adequately explained -- in our language, the word
"drone" has come to designate any lazy, parasitic person. Not only do
hymenopteran males contribute virtually nothing to the labor of the
colony, but they are also highly competitive in begging food from female
members of the colony and become quite aggressive in contending with other
males for access to females during the nuptial flights. Nature has even
provided a control experiment: termites are not haplodiploid and yet have
equaled the hymenopterans in social evolution, for different reasons that
will be discussed later. According to the theory termite males should not
be drones. And they are not. Males constitute approximately half of the
worker force, contribute and equal share of the labor, and are as
altruistic to nestmates as are their sisters.
"A second, nonobvious prediction of the theory is that worders of
hymenopteran colonies should favor their own sons over their brothers. In
other words, workers should lay unfertilized eggs and try to rear them to
the exclusion of the queen's unfertilized eggs. This bias follows in part
from the simple fact that females are related to their sons by a degree
of 1/2 but to their brothers by a degree of only 1/4. It is enhanced by
the relations between sister workers, in a manner to be explained
shortly. Although the result seems odd, it can be reasonably well
documented. Males are commonly derived from worker-laid eggs in nests of
paper wasps (Yamanka, 1928), bumblebees (Ronaldo Zucchi, personal
communication), stingless bees of the genus Trigona (Bieg, 1972), and ants
of the genera Oecophylla and Myrmica (Ledoux, 1950; Brian, 1968). The
origin of males from workers appears to be a widespread phenomenon in the
social Hymenoptera. But it is no universal; in the ant genera Pheidole and
Solenopsis, for example, ovaries are completely lacking in the worker
caste. "
...
"In summary, the kin-selection hypothesis predicts that to the
extent that workers control the reproduction of the colony -- one might
even say to the extent they "exploit" the queen -- the ratio of investment
will fall between 1:1 and 3:1 in favor of queen production. If the mother
queen is in control, that is "exploiting" the workers, the ratio should be
the usual Fisherian 1:1. For various species of ants thus far measured,
the ratio is significantly greater than 1:1, and in many cases it falls
very close to 3:1 (Trivers, 1975)."
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 08:04:40 MST