Morphological variation in anuran limbs: Constraints and novelties

FABREZI, M.; CHULIVER PEREYRA, M; GOLDBERG, J.

JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2017

1552-5007

Anurans have three primary types of locomotion: walking, jumping and swimming.Additionally they may dig, climb, grasp, etc. All adult anurans have four limbs, with fourfingers on the hands and five toes on the feet. We summarized and updated knowledge onthe interspecific variation within anuran limbs, then discuss how developmental constraints(for example in size) and novelties may have influenced anuran diversification through thelocomotion. We analyze morphological variation from limb bud stages up to the final limbform resulting from certain skeletal organization and growth. We find limited morphometricvariation in the skeleton of different developmental modules (i.e., skull, trunk, urostyle, limbs) indicate the anuran body shape is largely constrained. We identify specializations of the stylopodium, zeugopodium and proximal carpals/tarsals that have evolved to facilitiatesaltatorial locomotion. We show that the anuran prepollex and prehallux are not vestigialdigits and that they have come to serve specialized function. Medial rotation of the manusin anurans appears to have evolved to help distribute the force of impact upon landing at theend of a jump. Additional skeletal elements in anuran limbs are intercalary elements andsesamoids. The intercalary elements appear within neobatrachians and are integrated withdigital pads in lineages capable of locomotion on smooth vertical surfaces. They haveallowed arboreal anurans to occupy a wide range of arboreal habitats.