[TERMITE BIOLOGY] ET TU, ZOOTERMOPSIS?
3/23/2010
Because most termites are workers that stay in their parents’ colony their entire life and never reproduce, they contradicted Darwin’s "survival of the fittest" principle, which favors the traits that lead to reproductive success.
This was a big problem for Darwin and for evolution, explained Dr. Barbara Thorne, professor of entomology at the University of Maryland, whose recent "Accelerated Inheritance" study helped unravel this evolutionary mystery.
Worker termites, she found, were just waiting for the right time to seize the throne.
Thorne and colleagues studied dampwood termites (Zootermopsis nevadensis), a primitive species that stays confined to the wood it infests. They are the closest, living species sharing social, developmental and habitat characteristics with ancient ancestors.
Research found when neighboring, unrelated colonies met under bark, a battle ensued where kings and queens of one or both colonies were assassinated and cannibalized. The two colonies then joined forces, cooperating to form a larger colony, with new reproductives emerging from the worker ranks.
Sticking with the colony and working well with non-relatives improved a termite’s opportunity to inherit the "reproductive throne." This offered far greater success than the alternative: leave the colony, find a mate and reproduce fertile offspring without the support of an established colony.
...
Read more here/Leia mais aqui: PCT Online
+++++
Evolution of eusociality and the soldier caste in termites: Influence of intraspecific competition and accelerated inheritance
Barbara L. Thorne*,
Nancy L. Breisch, and
Mario L. Muscedere
-Author Affiliations
Department of Entomology, University of Maryland, College Park, MD 20742-4454
Edited by Bert Hölldobler, University of Wurzburg, Wurzburg, Germany, and approved August 25, 2003 (received for review June 9, 2003)
Abstract
We present new hypotheses and report experimental evidence for powerful selective forces impelling the evolution of both eusociality and the soldier caste in termites. Termite ancestors likely had a nesting and developmental life history similar to that of the living family Termopsidae, in which foraging does not occur outside the host wood, and nonsoldier helpers retain lifelong options for differentiation into reproductives. A local neighborhood of families that live exclusively within a limited resource results in interactions between conspecific colonies, high mortality of founding reproductives, and opportunities for accelerated inheritance of the nest and population by offspring that differentiate into nondispersing neotenic reproductives. In addition, fertile reproductive soldiers, a type of neotenic previously considered rare and docile, frequently develop in this intraspecific competitive context. They can be highly aggressive in subsequent interactions, supporting the hypothesis that intercolonial battles influenced the evolution of modern sterile termite soldier weaponry and behaviors.
Footnotes
↵ * To whom correspondence should be addressed. E-mail:bthorne@umd.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviation: mRS, male reproductive soldier.
↵ † In the most primitive living Termopsid, Archotermopsis wroughtoniDesneux, gonads of all soldiers are as well developed as in alates (44), but their fertility is not established.
↵ ‡ In formal termite terminology, Termopsidae do not have true workers because those individuals retain substantial developmental plasticity (35); however, in the functional sense that they help and work within the colony, we refer to them as helpers or workers in this paper.
Copyright © 2003, The National Academy of Sciences
+++++
PDF gratuito deste artigo aqui.
