Varanid Teeth Asymmetry and Correlation to Body Size

Area of Science:

• Comparative anatomy
• Vertebrate paleontology
• Evolutionary biology

Background:

• Stressors like injuries and hormone levels increase fluctuating asymmetry in vertebrates.
• Digit and skull asymmetry correlate with stress in snakes and lizards.
• Teeth asymmetry is a potential biomarker for stress and brain laterality.

Purpose of the Study:

• To investigate the relationship between body size and teeth asymmetry in the Varanidae lizard family.
• To determine if body size influences directional asymmetry in varanid teeth.

Main Methods:

• Landmark/semi-landmark analysis of 671 tooth pairs from 13 varanid species.
• Calculation of Centroid Size and asymmetry for each tooth pair.
• Statistical analysis of the correlation between body size and teeth asymmetry.

Main Results:

• Right-biased asymmetry was significantly greater in the upper tooth row.
• A significant positive linear correlation was found between body size and right-biased teeth asymmetry in Varanus, excluding V. komodoensis.
• V. komodoensis showed varied asymmetry trends based on size, with larger individuals exhibiting more scatter and left-biased asymmetry.

Conclusions:

• Body size is a significant factor influencing teeth asymmetry in Varanus lizards, potentially linked to environmental stressors.
• The unique asymmetry patterns in V. komodoensis may be due to ontogenetic niche shifts or other factors requiring further study.
• Body asymmetry, including teeth asymmetry, may reflect underlying brain laterality in reptiles.