Journal Article
Intraspecific variation in limblessness in vertebrates: a unique example of microevolution
Adriaens, D., Devaere, S., Teugels, G.G., Dekegel, B. and Verraes, W
Record Number:
4386
Year:
2002
Journal:
Biological Journal of the Linnean Society
Pages:
367-377
Volume:
75
Abstract:
The variation in limb reduction in vertebrates has generally been observed as characterizing higher-level taxa. Such
structural changes are thus considered to reflect macroevolutionary processes. A statistical analysis of metric variables
of some species of the African catfish family, Clariidae, suggests that fin reduction occurs at the microevolutionary
level as well. In at least three species of that family intraspecific variation in the presence/absence of the
pelvic fins was observed, and one species also showed similar variation for the pectoral fins. Discriminant function
analysis confirmed that the variation is intraspecific, and even occurs within the same population. Sexual dimorphism
could be excluded. This variation can be observed in the most anguilliform species of the clariid family, suggesting
a link with body elongation (as is the case in tetrapods that show limb reduction). Pelvic fin loss appears
to precede pectoral fin reduction during evolution. From the morphology it could be ascertained that the loss of the
pelvic fins is coupled to the loss of the pelvic girdle, contrary to the case for the pectoral fins and girdle. Differences
in functionality may explain this. Breeding results support the occurrence of intraspecific variation, as an F1 offspring
showed a difference compared with the parents. For at least one species, the benefit from body elongation
and limb reduction can be related to its highly specialized life style, as it lives subterraneanly in muddy soil of the
Central African rainforest.
Times Cited:
4