The Evolution of Skull Shape in Boana faber Clade: Unraveling Heterochrony's Influence

Abstract

Variation in shape and size within a lineage, driven by developmental processes, plays a key role in diversification. Here, we explore the effects of allometry and heterochrony on the skull shape evolution during the post-metamorphic period of species within the Boana faber clade, which vary considerably in body size. We analyzed 61 skulls of specimens belonging to eight species of the Boana faber clade, in addition to two outgroups, through 2D geometric morphometric analyses taken from CT-Scan images. Our results demonstrated that skull shape is considerably impacted by the size, represented by centroid size, and this effect can be observed from ontogenetic and evolutionary perspectives. In this way, we accessed the ontogenetic trajectories of analysed species and, in light of the phylogenetic hypothesis of the clade, we discussed the observed variation based on the concept of heterochrony, suggesting that a peramorphic pattern has evolved in the group.