RNA/DNA ratios in American glass eels ( Anguilla rostrata ): evidence for latitudinal variation in physiological status and constraints to oceanic migration?

Simon Laflamme (1) , Caroline Côté (1) , Pierre-Alexandre Gagnaire (1) , Martin Castonguay (2, 3) , Louis Bernatchez (1)

1 IBIS - Institut de Biologie Intégrative et des Systèmes [Québec]
2 Centre Hospitalier Universitaire de Québec
3 Institut Maurice-Lamontagne

During their larval leptocephalus phase, newly hatched American eels undergo an extensive oceanic migration from the Sargasso Sea toward coastal and freshwater habitats. Their subsequent metamorphosis into glass eel is accompanied by drastic morphological and physiological changes preceding settlement over a wide geographic range. The main objective of this study was to compare RNA/DNA ratios and condition factor among glass eels in order to test the null hypothesis of no difference in physiological status and metabolic activity of glass eels at the outcome of their oceanic migration. This was achieved by analyzing glass eel samples collected at the mouth of 17 tributaries covering a latitudinal gradient across the species distribution range from Florida to Gaspésie (Québec). Our main observations were (i) a latitudinal increase in mean total length; (ii) a latitudinal variation in mean RNA/DNA ratios, which was best explained by a quadratic model reaching its minimum in the central range of sampling locations; and (iii) a latitudinal variation in Fulton's condition factor, which was best explained by a quadratic model reaching its maximum in the central range of sampling locations. Below we discuss the possible links between latitudinal variation in glass eel physiological status and variable energetic and environmental constraints to oceanic migration as a function of latitudinal distribution.

Mots clés: phenotypic plasticity; RNA/DNA ratio Correspondence; Eel; fish; migration

Domaines: Biodiversité et Ecologie

Simon Laflamme, Caroline Côté, Pierre-Alexandre Gagnaire, Martin Castonguay, Louis Bernatchez. RNA/DNA ratios in American glass eels ( Anguilla rostrata ): evidence for latitudinal variation in physiological status and constraints to oceanic migration?. Ecology and Evolution, 2012, 2 (5), pp.875-884. ⟨10.1002/ece3.212⟩. ⟨hal-02395286⟩