Early morphological variation and induction of phenotypic plasticity in Patagonian pejerrey

Sonia A Crichigno,Víctor E Cussac,Miguel A Battini

doi:10.1590/s1679-62252012005000007

Sonia A Crichigno, Víctor E Cussac + Show 1 more

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https://doi.org/10.1590/s1679-62252012005000007

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Journal: Neotropical Ichthyology	Publication Date: Jun 14, 2012
Citations: 12	License type: cc-by

Affiliation: National University of Comahue

Abstract

The aim of this work was to study two aspects of phenotypic plasticity in the Patagonian pejerrey Odontesthes hatcheri (Teleostei: Atherinopsidae) the dependence of the early morphology on developmental time and temperature, and the induction of morphological changes by controlled feeding in juveniles. Newly hatched free embryos, incubated at two different temperatures (13 and 18oC), and juveniles were used for the study and induction of phenotypic plasticity. Body and head shapes were analyzed with geometric morphometrics and linear measurements. Our results showed that shape variation at hatching was related to the bending of the embryo head on the yolk sac, increasing the head-trunk angle due to progressive straightening of the embryo. The head-trunk angle was related with temperature at incubation, with embryos incubated at higher temperature being more bent. Embryos that hatched earlier had bigger yolk sacs than those that hatched later. In juveniles, controlled feeding experiments added new morphological variation to that of wild juveniles. In all comparisons, the slenderness of the head, the size of premaxilla and jaw, and the position of the eye showed an enlarged variation due to controlled feeding. These results will contribute to comprehending the complexity of the morphological variation of O. hatcheri.

Highlights

There is abundant evidence of phenotypic plasticity in fishes (Balon, 2004)
In the same way, combined effects of temperature, parental couples (PC), and days after fertilization (DAF) at AH 2, showed one significant Discriminant Function (DF) that correctly classified 92.2 % of cases and explained 100% of variation (DF1, N = 64, Wilkslambda = 0.344, P< 0.001)
Deformation grids from both comparisons showed that the individuals incubated at 18oC had their heads curved over the yolk sac, unlike individuals incubated at 13oC (Fig. 5)

Summary

Introduction

There is abundant evidence of phenotypic plasticity in fishes (Balon, 2004). It is considered as the ability of an organism to react to environmental input with a change in form, state, movement, or rate of activity (West-Eberhard, 2003), or as the property of individual genotypes to produce different phenotypes when exposed to different environmental conditions (Pigliucci, 2001; Pigliucci et al, 2006; Pfennig et al, 2010).Induced phenotypic plasticity has been studied extensively (Grünbaum et al, 2007). There is abundant evidence of phenotypic plasticity in fishes (Balon, 2004). It is considered as the ability of an organism to react to environmental input with a change in form, state, movement, or rate of activity (West-Eberhard, 2003), or as the property of individual genotypes to produce different phenotypes when exposed to different environmental conditions (Pigliucci, 2001; Pigliucci et al, 2006; Pfennig et al, 2010). Temperature modulates the amount of time required to complete embryonic development, within a specific range for each species (Kunz, 2004; Kamler, 2008), and has effects on the morphology, physiology, and behavior of fish during development (Martell et al, 2005). Environmental effects other than temperature can act along the ontogeny, inducing a certain morphology. Diet induced body and head shape variation has been observed in Cichlasoma managuense (= Parachromis managuensis) and Lepomis humilis (Meyer, 1987; Hegrenes, 2001)

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