17. Host Mediated Adaptation - Speculations about the alien species (Movies: Alien)
Description
This article is from the Alien Movies FAQ, by Darryll Hobsonand Eelko de Vos E.W.C.deVos@TWI.TUDelft.NL with numerous contributions by others.
17. Host Mediated Adaptation - Speculations about the alien species (Movies: Alien)
A further means to adapt to an environment is by adopting
strategies developed earlier by another species. The embryo is in a prime
position to learn about the metabolic and environmental conditions of its
host. Knowledge of local environmental conditions such as the pH,
atmospheric content and energy generation schemes would be important
for post emergence survival. Varying energy generation schemes may
result in differing metabolisms. Knowledge of the metabolic level and
requirements of the host gives an advantage to be used in hunting such
hosts. The development of the nymph might mimic other physical
attributes of the host as well. For example, if the host spent much time
hanging upside down, the nymph could develop that way as well, making
it a competent predator in an "upside down" environment.
Adult organisms are presumably adapted to their environment via
some combination of this host mediated process in concert with post-
emergence selection. In the primitive species, larval offspring of these
adapted adults will have to evaluate the state of the environment to
determine if they should seek a mobile host to find a more hospitable
environment, or if the should seek one to which they are adapted.
If a larva chooses a mobile host, its embryo may posses different
metabolic requirements or a generally different metabolism, which may
result in the death of the embryo after prolonged exposure. The nymph
must remain capable of aborting its development at the minimum possible
stage and emerging from the host, developing a new adaptive strategy
from the information gathered from the host, and surviving to reproduce
and create eggs adapted to the new environment. This minimum stage is
limbless, displaying only the buds of limbs, and uses the segmented tail
for propulsion.
If the larva chooses a host to which it is adapted, there will be
much less danger to the embryo from the host's metabolism, and the
nymph will be able to develop to its full form prior to emergence. This full
form possesses two sets of limbs in addition to the tail. It is possible
that a host chosen by a larva that detects no impending environmental shift
might be immobile or vegetative in nature.
Once a relatively stable environment has been located (in which
several rounds of reproduction were possible), a varying progression of
emergent nymph and adult forms might be observed, as pressures of
selection and host mediated adaptation refine the organism's strategy for
survival in the environment.
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