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Although physiology ensures homeostasis and fitness in a particular environment, and ecological shifts cannot be realized without physiological changes, metabolic transformations during animal adaptive radiations still remain unexplored. We present a study of energy reserve storage in the salmonid assemblage inhabiting a cold-water Lake Kronotskoe. This assemblage diversified from Salvelinus malma and includes eight distinct ecomorphs with contrasting lifestyles and trophic specializations. We hypothesized that ecomorphs differ in energy storage and expenditure, and that their metabolic phenotypes should be among the primary targets of natural selection. To test this hypothesis, we compared the stored amount and ratio of carbohydrates, lipids, circulating peptides that supply the citric acid cycle, as well as proxy indicators of metabolic rate, the blood levels of plasma proteins (including albumin) and hemoglobin. Among ecomorphs, numerous significant differences in physiological parameters were found, closely related to the composition of food, the depth of habitat, and determined by internal factors, probably genetics. Each ecomorph has a specific metabolic phenotype corresponding to its tropho-ecological specialization and lifestyle. Metabolically advanced predators accumulate lipids; littoral insectivorous morphs grow slower and accumulate glycogen; amphipod feeders do not accumulate spare substances; the deepwater consumer of silt benthos differs in the most divergent physiological characteristics. We assume a specific selection on endocrine regulators of energy metabolism during the adaptive radiation of the assemblage, among which the most plausible candidates are thyroid hormones and leptin. [ABSTRACT FROM AUTHOR]

El'gygytgyn is the only ancient lake in the Arctic that avoided continental-scale glaciations. This lake is located on an arid mountain plateau, far from the main routes of post-glacial freshwater fish dispersal, and it is therefore challenging to consider the local fauna in a historical context. Here we present a study of the ecology and evolutionary history of the local charr complex (genus Salvelinus). We found that the endemic charrs exhibit extreme longevity, contrasting lifestyles and phenotypes. Salvelinus svetovidovi is a relic benthivorous species. The remaining charrs are descendants of Salvelinus taranetzi. Mitochondrial and microsatellite DNA polymorphisms analyzed in them and in charrs from surrounding basins indicate that S. taranetzi invaded the lake from Arctic Chukotka in the late Pleistocene as two distinct, previously diverged lineages. Descendants of both lineages occupied the pelagic food chain. The first lineage has flourished as a monomorphic planktivorous population since colonization. The second represents an example of a recent in-lake adaptive divergence, in which a deepwater piscivore specialist formed a new epilimnetic ecomorph of an impressive size (up to 9.0 kg). We suggest that this diversification was triggered by modern warming in the Arctic, which led to the formation of a productive littoral ecosystem. [ABSTRACT FROM AUTHOR]

Analysis of the developmental sequence variability provides data linking the ontogeny and phylogeny of the investigated objects. Here, we present a study of cranial ossifications sequence variability in the polyphyletic group of Cyprininae Barbus sensu lato (Cypriniformes, Teleostei). We analyzed the intra- and interspecific variability, compared sequences of closely related and phylogenetically distant species, reconstructed an alleged ancestral sequence, and assessed the sequence variations' evolutionary validity. As the results, we revealed that the observed sequence alterations occur due to intrinsic, likely genetic or epigenetic factors. The skull ossifications, as well as skull regions, differ in the variability level. The ossifications appearing at the intermediate phase and skull regions composing splanchnocranium are most variable. In contrast, the structures emerging at the early and late phases of skull development and regions of neurocranium are less variable. The majority of sequence alterations are non-adaptive and selectively neutral. Increase in their number accompanying the transition from intra- to interspecific and intergeneric levels resembles the accumulation of the selectively neutral genetic variations accompanying the increase of phylogenetic distance. Reconstructions of phylogenetic relationships between investigated species obtained with the analyses of sequence similarity and phylogenetic analyses using parsimony (PAUP) are consistent with the phylogenies based on molecular data and thus demonstrate the potential of sequence analysis for phylogenetic inference. [ABSTRACT FROM AUTHOR]

Volcanoes serve as natural laboratories expanding our understanding of the recent and past ecological and evolutionary processes. Here, we present data elucidating the developmental and phenotypic transformations providing rapid adaptation for the salmonid fish, Salvelinus malma, to volcanic impact. After being isolated by the mudflow in 1996, the locked descendants of sea-run charr managed to survive in the highly turbid and toxic environment. Initially, the population underwent a phase of high developmental instability accompanied by a surge in morphological deviations. Further, selection targeted the fish prone to migrate into the most toxic mainstream favoring a sedentary lifestyle at the less toxic spawning tributaries. In five–seven generations, the sedentary population recovered developmental homeostasis but diverged into a small-sized short-cycled form with low phenotypic variability. In response to toxicosis, the fish displayed an accelerated metabolic rate and precocious maturations. The spawners possessed fry morphology with no spawning dress. Sedentary fish also exhibited a decreased fecundity and did not build spawning nests. Thus, under the volcanic impact, S. malma demonstrated a rapid paedomorphic miniaturization, an evolutionary mechanism enabling to complete the reproductive cycle under the conditions of high risks of reaching the adaptive capacity limits. [ABSTRACT FROM AUTHOR]