Reproductive traits in the southernmost landlocked population of the fish Galaxias maculatus

BOY, C.C.; ROJO, J.H.; FRAYSSE, C.P.; ODETTO, A.R.; AURELIANO, D.R.; PÉREZ, A.F.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2023

0018-8158

Thiswork aimed to study the reproductive traits of the southernmostlandlocked population of Galaxiasmaculatusliving under extreme environmental conditions (54.5ºS). Individualswere measured, weighed, sexed, and dissected. The reproductive cyclewas analyzed based on the monthly variation of the gonadosomaticindices (GSI) and the monthly proportion of gonadal stages(established through histology). Fecundity was evaluated by countingmacroscopically hydrated oocytes. The reproductive season of G.maculatusin the population assessed extended from March through November (themore protracted for the species described so far). The GSI was higherin males than females, with maximum individual values occurring atthe final maturation stage. The simultaneous presence ofpostovulatory follicles and developing oocytes indicates iteroparity.Our results suggest lower instantaneous investment in reproduction atthe individual level but a more prolonged throughout the year thanother populations of the species, even under more extreme winterconditions. Considering the increased reproduction costs underextreme habitats and based on our findings, we suggest howpopulations from the same geographic area can deploy differentstrategies to cope with energy trade-offs. These results highlightthe importance of integrated physiological and ecological approachesto elucidate the basis for variation in life-history traits.