Invisible pair bonds detected by molecular analyses.

Area of Science:

• * Evolutionary biology
• * Animal behavior
• * Ichthyology

Background:

• * Pair bonds are crucial for understanding social organization evolution.
• * Traditional identification of pair bonds relies on observable physical proximity.
• * Such methods may overlook pair bonds in species lacking visible pairings, like schooling fish.

Purpose of the Study:

• * To investigate the existence of pair bonds in Xenotilapia rotundiventralis, a cichlid fish species.
• * To determine if mating pairs maintain bonds during the hypothesized female-to-male transfer of young.
• * To provide the first evidence of pair bonds in a species where physical proximity is not observed.

Main Methods:

• * Conducted parentage analysis using 10 microsatellite markers.
• * Analyzed genetic relationships between mouthbrooding adults and the young in their mouths.
• * Utilized genetic data to infer mating pair associations and bond duration.

Main Results:

• * Parentage analysis confirmed mouthbrooding adults as the genetic parents of the young.
• * Findings strongly suggest that the transfer of young occurs between established mating partners.
• * This indicates that pair bonds are maintained at least until the young are shifted from female to male.

Conclusions:

• * Xenotilapia rotundiventralis exhibits pair bonds, challenging the necessity of physical proximity for their detection.
• * The study demonstrates a novel method for identifying pair bonds in schooling species.
• * This research advances the understanding of social organization and mating systems in fish.