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Developmental origin of limb size variation in lizards
Robin M Andrews1, Sable A Skewes1
1Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia.
Evolution & Development
|May 3, 2017
Summary
Species-specific differences in lizard limb and tail lengths emerge abruptly during early embryonic development, not gradually. This finding highlights the importance of early developmental processes in shaping adult reptile morphology and evolutionary adaptations.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Comparative Anatomy
Background:
- Reptile hatchlings possess adult morphology, indicating its emergence during embryonic development.
- Understanding embryonic development is key to linking phenotypic variation mechanisms with natural selection on post-hatching individuals.
Purpose of the Study:
- To investigate the timing of species-specific differences in limb and tail lengths during embryonic development in lizards.
- To differentiate between gradual (continuous allometry) and abrupt (transpositional allometry) emergence of size differences.
Main Methods:
- Comparative analysis of allometric patterns in early limb growth across four lizard species.
- Observation of limb and tail bud development during embryogenesis.
Main Results:
- Species-specific differences in limb and tail lengths were observed to emerge abruptly (transpositional allometry).
- These differences were evident as early as the limb and tail buds protruded from the body wall.
Conclusions:
- Early embryonic development, specifically the initial bud formation stage, establishes species-specific limb and tail length differences in lizards.
- Investigating genes involved in early tetrapod limb development is crucial for understanding the genetic basis of interspecific variation in limb length.
- Comparative gene regulation studies can illuminate mechanisms of adaptive variation in limb size, including reduction and loss, in squamate reptiles.
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