Morphological integration during postnatal ontogeny: implications for evolutionary biology

Area of Science:

• Evolutionary biology
• Developmental biology
• Quantitative genetics

Background:

• Understanding how phenotypic covariance evolves during development is crucial for evolutionary insights.
• Mammalian cranial covariance patterns are known to change during ontogeny (development).
• The impact of ontogenetic variation in covariance on evolutionary response to selection remains unclear.

Purpose of the Study:

• To quantify changes in covariance patterns during postnatal development.
• To identify ontogenetic stages with the most significant covariance differences.
• To assess if developmental covariance patterns share underlying processes with additive genetic covariance.

Main Methods:

• Analysis of postnatal ontogenetic series in marsupials and placentals.
• Comparison of phenotypic covariance matrices (P-matrices) across developmental stages.
• Comparison of developmental P-matrices with adult P-matrices and additive genetic covariance matrices (G-matrices).

Main Results:

• Covariance patterns were conserved from weaning onwards across all studied ontogenetic series.
• Conserved covariance patterns likely share underlying processes with the additive genetic covariance matrix (G-matrix).
• Developmental covariance patterns showed significant differences in early ontogeny but stabilized later.

Conclusions:

• Phenotypic covariance patterns stabilize after weaning during postnatal ontogeny.
• The processes shaping the additive genetic covariance matrix (G-matrix) likely also shape later developmental covariance.
• Ontogenetic changes in covariance patterns are unlikely to significantly affect the net evolutionary response to selection after weaning.