Una aproximación filogenética al estudio del dimorfismo sexual de tamaño en Felidae y la evaluación de la regla de Rensch

Abstract

Martinez, P.A., Ferreira Amado, T., Bidau, C.J. 2014. A phylogenetic approach to the study of sexual size dimorphism in Felidae and an assessment of Rensch´s rule. Ecosistemas 23(1):27-36. Doi.: 10.7818/ECOS.2014.23-1.05 Sexual size dimorphism (SSD) is a poorly understood phenomenon with respect to its ontogenetic and evolutionary causes, and generalizations such as Rensch's rule that interprets the relationship between SSD and body size, have not been satisfactorily supported. We chose the Felidae to perform a comparative study of SSD because of its morphological homogeneity, reproductive characteristics, and range of body sizes. We posed three hypotheses: 1. polyginy that occurs in all felid species a predicts a high degree of male-biased SSD; 2. since a great variance in body size occurs, we predicted that, if Rensch's rule is verified, the sensibility of the employed methods will detect it in a sample comprising the whole size range; 3. since in Carnivora size is correlated with many ecological and life-history variables, if SSD scales with size according to Rensch's rule, it would be expected that SSD would be also correlated  with some of these variables. We constructed a databse of body masses and lengths of males and females of 90 % of the species of Felidae. We studied SSD and its relation to body size and performed comparisons with life-history, cliamtic, and geographic variables of all species usan phylogenetically independent contrasts (PICs). Felids showed high levels of SSD for body mass which could be the result of the polygynic behaviour and low/null male parental care generalized in the family. SSD did not show a relationship with body size thus not supporting Rensch's rule: SSD and body mass have completely non-coincident phylogenetic distribution patterns. Aslo, SSD did not show any correlation with the analyzed predictors. A larger number of studies at the intraspecific level of species with large distributions is needed to evaluate geographic size variation and its impact on SSD and to understand the mechanisms that modulate SSD within the family.