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Morphological integration and developmental progress during fish ontogeny in two contrasting habitats
Laurence Fischer-Rousseau1, Richard Cloutier, Miriam Leah Zelditch
1Laboratoire de Biologie évolutive, Université du Québec à Rimouski, Rimouski, QC G5L 3A1, Canada.
Evolution & Development
|November 3, 2009
Summary
Brook charrs (Salvelinus fontinalis) show distinct developmental periods influencing morphological integration. Juvenile body shape variability may not reflect early developmental signals, cautioning against inferring early causes from later stages.
Area of Science:
- Evolutionary biology
- Developmental biology
- Ichthyology
Background:
- Morphological integration can be influenced by environmental factors and change dynamically during an organism's development.
- Brook charrs (Salvelinus fontinalis) exhibit trophic polymorphism, making them an ideal model for studying the ontogeny of morphological integration.
Purpose of the Study:
- To investigate the ontogenetic dynamics of morphological covariances and developmental progress in brook charrs from contrasting lake and stream habitats.
- To understand how environmental factors like water velocity shape developmental trajectories and integration patterns.
Main Methods:
- Utilized geometric morphometrics on 751 specimens and developmental progress analysis on 198 specimens of Salvelinus fontinalis.
- Compared populations from lake and stream environments, focusing on ossification events and shape changes across ontogeny.
Main Results:
- Identified two distinct developmental periods: early (alevins) with rapid shape change and decreasing integration, and later (juveniles) with stabilized shape and increasing integration.
- Observed significant decreases in shape variance during the alevin stage and stabilization during the juvenile stage.
- Found stability in the underlying ontogenetic dynamics of variability and gradual changes in covariation structure within each habitat.
Conclusions:
- Juvenile body shape variability may not retain signals from early ontogeny, suggesting caution when using juveniles to infer earlier causes of variation.
- Inferring the causes of morphological integration from static covariance studies presents significant challenges.
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