Cockroache; Ecology, behavior & history - W.J. Bell

sects, self-organization has been shaped by natural selection
to produce task specialization, and plays a role in
building behavior, decision making, synchronization of
activities, and trail formation (Page and Mitchell, 1998;
Camazine et al., 2001).
THE GROUND PLAN
Nature has set a very high bar for the attainment of eusociality,
and only extraordinary environmental challenges
and extraordinary circumstances in prior history can allow
an organism to scale it (Hölldobbler and Wilson,
2005). In the termite ancestor, a nitrogen-deficient, physically
difficult food source was undoubtedly the relevant
environmental challenge, and costly brood care was an essential
precedent. Nonetheless, the evolution of termite
eusociality cannot be divorced from an entire suite of interrelated
and influential morphological, behavioral, developmental,
and life history characteristics. These include
monogamy, altricial offspring, adult longevity,
extended developmental periods, multiple relationships
with microbial symbionts, proctodeal trophallaxis and
other food-sharing behaviors, reproduction and development
that closely track nutritional status, and semelparity
with age differentials within the brood (Nalepa, 1984,
1994). So many conditions were interrelated, aligned, and
influential in the transition that any attempt to reduce an
explanation to a few basic elements is an oversimplification.
It is important to note, however, that in integrated
character sets such as these, selection on just one
character can lead to changes in associated characters,
and these changes can occur with a minimum of genetic
change. It is in this manner that paedomorphic evolution
often proceeds, with small tweaks in regulatory genes that
result in maximum impact on an evolutionary trajectory
(Gould, 1977; Futuyma, 1986; Stanley, 1998). It is also notable
that all ground plan elements are found among extant
cockroaches, and that the core process, as in other social
insects (Hunt and Nalepa, 1994; Hunt and Amdam,
2005), is a shift in life history characters mediated by a
nutrient-dependent switch.
164 COCKROACHES