Morphological Castes in a Vertebrate

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 97; no. 24; pp. 13194 - 13197
• Main Authors: O'Riain, M. J., Jarvis, J. U. M., Alexander, R., Buffenstein, R., Peeters, C.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 21.11.2000; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Analysis of Variance; Animal reproduction; Animals; Animals, Laboratory; Biological Sciences; Breeding; Evolution; Female; Female animals; Genetic Variation; Heterocephalus; Insect castes; Insect colonies; Insect morphology; Insect reproduction; Male; Male animals; Mating behavior; Mole Rats - anatomy & histology; Mole Rats - genetics; Mole Rats - physiology; Regression Analysis; Reproduction - physiology; Rodents; Social insects; Vertebrates; Zygoma - anatomy & histology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.97.24.13194

Morphological specialization for a specific role has, until now, been assumed to be restricted to social invertebrates. Herein we show that complete physical dimorphism has evolved between reproductives and helpers in the eusocial naked mole-rat. Dimorphism is a consequence of the lumbar vertebrae lengthening after the onset of reproduction in females. This is the only known example of morphological castes in a vertebrate and is distinct from continuous size variation between breeders and helpers in other species of cooperatively breeding vertebrates. The evolution of castes in a mammal and insects represents a striking example of convergent evolution for enhanced fecundity in societies characterized by high reproductive skew. Similarities in the selective environment between naked mole-rats and eusocial insect species highlight the selective conditions under which queen/worker castes are predicted to evolve in animal societies.