Parental behavior drives large bite force in an insular skink population

• Published in: Journal of zoology (1987) Vol. 307; no. 3; pp. 223 - 231
• Main Authors: Tseng, H.‐Y., Liao, C.‐P., Hsu, J.‐Y., Wang, L.‐Y., Huang, W.‐S.
• Format: Journal Article
• Language: English
• Published: London Blackwell Publishing Ltd 01.03.2019
• Subjects: Adaptation; Animal behavior; Animal reproduction; Biological competition; bite force; Biting; Body weight; Breeding success; Competition; Courtship; Eutropis longicaudata; Females; Force measurement; Guarding behavior; Head; Interactions; Interspecific relationships; Lizards; long‐tailed skink; Males; Oligodon formosanus; Ova; Parental behavior; Parental behaviour; parental care; Population studies; Populations; Predation; Predators; Prey; Reproduction; Reproductive behaviour; Sexual behavior; sexual dimorphism; Sexual selection; Skin; Snake bites; Orchid Island
• ISSN: 0952-8369; 1469-7998
• DOI: 10.1111/jzo.12638

Different environments may drive the evolution of morphological traits due to selection on organismal performance. In lizards, bite force plays an important role both for inter‐ and intra‐specific interactions, such as prey preference, resource competition, predatory defense, and courtship behavior. Individuals with large bite force may benefit from a high reproductive success through territorial defense or predatory deterrence. Under extremely high predation risk from the oophagic kukri snake (Oligodon formosanus), long‐tailed skinks (Eutropis longicaudata) on Orchid Island exhibit an exclusive post‐ovipositional parental care, not found in any other populations. In this study, we tested the assumption that Orchid Island skinks exhibit higher bite force than two other populations without egg‐guarding behavior. We investigated the three hypotheses that best explain this adaptation: (1) Orchid Island skinks have different parental care than Green Island and Taiwan skinks, which may drive larger bite force; (2) in the three populations, male–male competition and mating bites enhance bite force, leading males to present higher bite force than females; (3) head traits are indicators of bite force. Our results show for the first time that Orchid Island skinks exhibit larger bite force than the other populations do, which may be shaped by a higher egg‐predation pressure and the consequent parental behavior. Males exhibit stronger bite force likely due to a stronger sexual selection. Bite force of long‐tailed skink is positively correlated with larger body weight and head length, and the larger head can further enhance bite force for males in sexual selection. Bite force plays an important role both for inter‐ and intra‐specific interactions. Under extremely high predation risk from the reptile‐egg eating snake (Oligodon formosanus), long‐tailed skinks (Eutropis longicaudata) on Orchid Island display a unique egg‐guarding behavior, which drives larger bite force than in other populations without parental care. Males in three populations exhibit stronger bite force likely due to stronger sexual selection. Our study provides the first evidence that maternal care can drive higher bite force in lizards. Such higher bite force may have genetic‐based interaction, because in the same population, the males also have stronger bite force than in the other two male populations.