Evolutionary patterns of cranial ontogeny in sigmodontine rodents

SEGURA V.; FLORES D.; JAYAT J. PABLO; MARTIN GABRIEL

JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021

0947-5745

Sigmodontines comprise one of the most diverse radiations of mammals.The cranial ontogeny has been studied in several mammals, but remains poorlystudied in the group. We quantified theontogenetic pattern for 22 sigmodontine species and 8 outgroups, generatingpartial reconstructions of ancestral allometric growth patterns, and testingthe role of evolutionary history on cranial ontogeny. Sigmodontines wereconservative in growth pattern, without unique patterns defining tribes. The allometric growth of thecranium was mostly negative, with Akodontini being the most isometric andPhyllotini the most allometric tribes. Allometry of variablesassociated with the neurocranium were mostly negative, while those linked totrophic functions showed positive allometry or isometry. A general craniallengthening was detected, but variables associated with cranial width or heightgrew at lower rates. Cranial growth and development were associated with changes in themusculature functionally involved in bite and mastication. Most changesoccurred in earlier postnatal stages, achieving an early morphological optimum.Few changes in the rate of growth at internalnodes were detected, and the stasis along the backbone was recurrent. Cranial elongation was a pattern widespread in thesample, and likely a plesiomorphic condition. The few synapomorphies definingthe ancestor of Sigmodontinae conform to a pattern with zygomaticarches little expanded laterally and globose braincases. The conservative pattern maybe attributed to the biomechanically optimal morphology for omnivorous diets,suggesting that the generalized morphology allows the exploitation of multipletypes of food with minor morphological adjustments.