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Dynamic evolutionary interplay between ontogenetic skull patterning and whole-head integration
Joni Ollonen1, Eraqi R Khannoon2,3, Simone Macrì1
1Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
Nature Ecology & Evolution
|January 10, 2024
Summary
Snake and lizard skull evolution resulted from gradual changes in spatial and temporal development. Sensory organs significantly influenced skull shape, revealing key insights into vertebrate craniofacial development.
Area of Science:
- Evolutionary biology
- Developmental biology
- Comparative anatomy
Background:
- Vertebrate skull morphology is adaptable, reflecting function and ecology.
- Underlying developmental and macroevolutionary mechanisms of skull diversity are not fully understood.
Purpose of the Study:
- To investigate developmental and evolutionary patterns of skull variation in squamate reptiles.
- To analyze skull shape and covariation throughout ontogeny in snakes and lizards.
Main Methods:
- Geometric morphometrics applied to a large dataset of squamate specimens (209 individuals, 169 embryos, 44 species).
- Analysis spanned from early craniofacial development to fully ossified skulls.
Main Results:
- Skull differences between snakes and lizards evolved via heterotopy (spatial changes) and heterochrony (timing/rate changes).
- Phenotypic integration of the developing snake head is higher than in lizards, influenced by sensory organ development (eyes, nasal cavity, Jacobson's organ).
Conclusions:
- Early embryonic and ontogenetic interactions, particularly sensory organ influence, are crucial for craniofacial evolution and diversification in squamates.
- Findings offer insights into cranio-cerebral relationships across vertebrates.
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