Address for correspondence: Scott F. Gilbert, Department of Biology, Swarthmore College, Swarthmore, PA 19108. Voice: 610-328-8049.
sgilber1{at}swarthmore.edu
Ann. N.Y. Acad. Sci. 981: 202-218 (2002).
Epigenesis concerns the interactions through which the inherited
potentials of the genome become actualized into an adult organism.
In addition to epigenetic interactions occurring within the
developing embryo, there are also critical epigenetic interactions
occurring between the embryo and its environment. These interactions
can determine the sex of the embryo, increase its fitness, or
even be involved in the formation of particular organs. This
essay will outline the history of environmental concerns in
developmental biology and provide some reasons for the decline
and resurgence of these ideas, and it will then focus on two
areas that have recently gained much attention: predator-induced
polyphenisms and developmental symbioses. Research in these
two areas of interspecies cooperation in morphogenesis has profound
implications for what we consider to be normal development and
how we proceed to study it. Studies of predator-induced polyphenism
have shown that soluble factors from predators can change the
development of prey in specific ways. Prey has evolved mechanisms
to sense compounds released from their predators and to use
these chemical cues to change their development in ways that
prevent predation. New techniques in molecular biology, especially
polymerase chain reaction and microarray analysis, have shown
that symbioses between embryos and bacteria are widespread and
that animals may use bacterial cues to complete their development.
