Sistemática e Evolução - Pôsteres - 29/11/2023 - 15:30 h às 16:30 h

Coronula diadema barnacle is a filter-feeding epibiont, with a larval stage that typically settles on humpback whales (Megaptera novaeangliae). This study aimed to investigate potential differences in the adult barnacle's morphology considering two main factors: 1) the host's sex, as males exhibit more aggressive behavior during competition for mature females, including body, head, and tail slaps, suggesting possible variations in barnacle shape depending on the host's sex; 2) the settlement location on the host's body, as different regions may experience distinct hydrodynamic conditions and nutrient availability, potentially influencing barnacle morphology. 196 barnacles were collected from 21 humpback whales found stranded in the states of Bahia, Rio de Janeiro and Rio Grande do Sul, along the Brazilian coast. Morphometric analyses were conducted using dorsal and lateral photographs, with 11 and seven landmarks, respectively, all properly scaled. A Procrustes analysis was applied to generate a covariance matrix, which was then subjected to principal component analysis (PCA) to identify differences among predefined groups (ventral grooves, pectoral fins, and genitals; male and female). Preliminary results revealed slight differences between males and females in lateral photographs and variations between pectoral fins, ventral grooves, and genitals in dorsal photographs. The first two components of PCA explained eigenvalues of 75% in lateral photographs and 45% in dorsal photographs. By averaging the data based on sex in both lateral and dorsal photographs, the primary source of variation was associated with PC1. Regarding settlement location, higher variation was observed in PC2 in dorsal photographs, confirming the existence of morphometric differences related to settlement. Overall, this study sheds light on the potential influence of host sex and settlement location on the morphology of C. diadema barnacles attached to humpback whales, providing valuable insights into the ecological and evolutionary dynamics between the epibiont and its host.