Early morphological variation and induction of phenotypic plasticity in Patagonian pejerrey

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.O objetivo deste trabalho foi estudar a variação morfológica e plasticidade fenotípica do peixe-rei da Patagônia Odontesthes hatcheri (Teleostei: Atherinopsidae), a dependência da morfologia inicial no tempo de desenvolvimento e temperatura, e a indução de alterações morfológicas pela alimentação controlada em juvenis. Embriões recém-nascidos, incubados a duas temperaturas diferentes (13 e 18ºC) e juvenis foram utilizados para o estudo de indução de plasticidade fenotípica. Formas do corpo e cabeça foram analisadas com técnicas de morfometria geométrica e medições lineares. Os nossos resultados mostraram que a variação da forma no nascimento foi relacionada com a curvatura da cabeça do embrião no saco vitelino, aumentando o ângulo de cabeça-tronco devido ao endireitamento progressivo do embrião. O ângulo da cabeça-tronco relacionou-se com a temperatura de incubação, com os embriões incubados na temperatura elevada sendo mais curvados. Os embriões que eclodiram mais cedo tinham sacos vitelinos maiores do que aqueles que eclodiram tardiamente. Em juvenis, os experimentos de alimentação controlada adicionaram nova variação morfológica àquela dos juvenis selvagens. Em todas as comparações, a espessura da cabeça, o tamanho da pré-maxila e mandíbula, e a posição do olho mostraram uma maior variação devido à alimentação controlada. Estes resultados irão contribuir para a compreensão da complexidade da variação morfológica de O. hatcheri.

Phenotypic diversity, population structure and stress protein-based capacitoring in populations of Xeropicta derbentina, a heat-tolerant land snail species

“…Heat stress can influence phenotypic variation (Child et al 1940;Imasheva et al 1997;Royer et al 2009;Sisodia and Singh 2009;Hansen et al 2011;Crichigno et al 2012) and chaperones were suggested to canalize phenotypic development and, therefore, to act as capacitors of phenotypic variation (Rutherford and Lindquist 1998;Roberts and Feder 1999;Queitsch et al 2002;Rutherford 2003). Thus, it seems reasonable to hypothesize that they also participate in the regulation of phenotypic variation in natural populations of polymorphic land snails.…”

Native and exotic fishes in a Patagonian reservoir with rainbow trout cage culture: spatial and trophic resource use

“…Although both species fed extensively on Daphnia, O. hatcheri consumed more snails, and less terrestrial insects, whereas rainbow trout showed the opposite pattern. This difference could be the consequence of the stenophagous character of adult O. hatcheri (Crichigno et al, 2012), past competition leading to trophic and spatial segregation (i.e. less pelagic, more littoral-benthic habits for O. hatcheri), and/or the result of O. hatcheri abandoning the western side of the reservoir (sites MH and CL; Cussac et al, 2014 and present results) where coasts are forested and abundance of terrestrial insects (hemipterans of the exotic Pinus spp.)…”

Populations of Odontesthes (Teleostei: Atheriniformes) in the Andean region of Southern South America: body shape and hybrid individuals

“…In agreement with Aigo et al (2008), who positively relate abundance of O. hatcheri to the area of the lake, and the dependence of cephalic shape of O. hatcheri on coastline development (Crichigno et al, 2013), significant relationships between DFs and independent variables affecting quality and quantity of planktonic food availability (TP and altitude) were observed. Part of this variation could be ascribed to phenotypic plasticity (Crichigno et al, 2012).…”

“…Morphometric analyses can effectively discriminate between the species and their putative hybrids, in spite of the very small morphological differences, even when morphological variation includes the possible effects of genetic introgression, environmental dependence, and phenotypic plasticity (Crichigno et al, 2012).…”