Sex and male breeding state predict intraspecific trait variation in mouth‐brooding fishes

Abstract

Sex-specific reproductive roles contribute to sexual dimorphic morphological trait variations. In uniparental mouth-brooding fishes, the mouth performs a reproductive function in addition to its key roles in feeding and respiration, resulting in the potential for sex-specific functional performance trade-offs. Trait differences related to parental care may occur when the individual matures or be restricted to periods when the parent is mouth-brooding. This study explored sexual dimorphism and morphological trait adaptations related to feeding, breeding, respiration and locomotion performance in two paternal mouth-brooding freshwater fishes (Glossamia aprion and Neoarius graeffei). Eight morphological traits were evaluated for sexual dimorphism (non-brooder males vs. females) and male breeding state differences (brooders vs. non-brooders). Male breeding state was a significant predictor of trait variation in both species. Brooders differed in buccal volume and in several feeding and locomotory traits compared to non-brooder males. Non-brooder males had bigger buccal volumes and relative eye diameters (G. aprion) and larger relative gape sizes (N. graeffei) compared to females, a potential response to both mouth-brooding and feeding requirements. Although there were clear trait differences between brooder and non-brooder males, further research is required to confirm whether individuals return to their former morphology once mouth-brooding has ceased or if trait differences are maintained post-brooding. This study highlights the importance of considering the potential impacts of intraspecific trait variation on the performance of critical life functions, such as feeding, respiration and locomotion across the life history.

Sexual Dimorphism and Discrimination of Barbel Steed (Hemibarbus labeo) in the Jinhe River, China: An Indicator of Habitat Status

“…Animal sexual size dimorphism (SSD) is usually explained as a result of sexual selection, ecological selection, and fertility selection [8,[43][44][45]. Fish have three main SSD types: (1) female adults are larger than male adults; (2) female adults are smaller than male adults; and (3) males and females are similar in size, but there are differences in local characteristics [46][47][48].…”

Description of eight new mitochondrial genomes for the genus Neoarius and phylogenetic considerations for the family Ariidae (Siluriformes)

“…The reproductive period for these species typically starts in spring, around September, and extends until the end of summer, in February. Notably, N. graeffei employs a rare reproductive strategy known as mouthbrooding, where the eggs are incubated in the mouth of the adult individual until they mature enough to be independent [ 3 ].…”