Multi-year pair-bonding in Murray cod (Maccullochella peelii)

Area of Science:

• Evolutionary biology
• Ichthyology
• Molecular ecology

Background:

• Mating strategies in fishes, including polygyny, polyandry, and monogamy, are crucial for understanding sexual selection.
• Monogamy in freshwater fishes has been understudied, with most research focusing on marine species and observational methods.
• Long-term pair bonding, common in other vertebrates, has not been previously documented in wild freshwater fishes.

Purpose of the Study:

• To investigate the occurrence of long-term pair bonding and monogamous mating strategies in a wild freshwater fish species.
• To apply advanced molecular techniques for inferring mating behaviors in the absence of parental genotypes.
• To provide insights into the evolutionary dynamics of mating systems in freshwater ichthyofauna.

Main Methods:

• Utilized single nucleotide polymorphisms (SNPs) as a molecular tool for genetic analysis in a non-model organism.
• Employed probabilistic genetic analysis methods to infer sibling relationships and mating strategies without parental genotypes.
• Analyzed stable isotope signatures in larvae to corroborate genetic findings regarding maternal lineage.

Main Results:

• Demonstrated multi-year pair bonding in an Australian Percichthyid fish exhibiting paternal care.
• Identified full sibling pairs of larvae across multiple years using SNP data, confirming monogamous mating.
• Stable isotope data supported the genetic inference of shared maternal origin for sibling larvae.
• Spatial and temporal clustering of sibling larvae reduced the likelihood of false positive identifications.

Conclusions:

• Established the first evidence of multi-year pair bonding in a wild freshwater fish.
• Highlighted significant conservation and management implications for the studied species.
• Proposed the SNP-based approach as a valuable tool for studying mating strategies and behavioral ecology in diverse freshwater fish populations.
• Encouraged further research into monogamy and alternative mating strategies in freshwater fishes, alongside improvements in SNP data analysis methods.