An
essential component to understanding the unique nature of the axolotl is
having knowledge of the terms used to describe its role as a fully aquatic
amphibian. Many books, journal articles, and web sites use different
words to discuss the axolotl's development pattern. The following
is a list of the most common terms:
-
Neoteny:
a phenomenon brought about by the maturation of the reproductive system
in a larval form that fails to undergo metamorphosis (Gilbert and Raunio
1997)
-
Paedomorphosis:
the retention of ancestral juvenile characteristics in a descendant adult
species (Shaffer 1993)
-
Paedogenesis:
reproduction in the larval state (Rosenkilde and Ussing 1996)
As these definitions
suggest, the axolotl is a fully aquatic, sexually mature amphibian that
fails to completely metamorphose, and therefore retains some ancestral
juvenile characteristics. Within morphological literature, there
is no single term that seems to descriptively encompass all three of these
definitions. In fact, some appear to be used somewhat interchangeably.
Some biologists, like Gould, make convincing arguments to suggest that
neoteny applies only to examples where there is solid understanding of
the organism's evolutionary developmental history (Voss and Shaffer
1996). For the purposes of this web page, however, the use of any
one of these words will be in accordance with the source of that particular
information. |
