Insights into adaptive behavioural plasticity from the guppy model system.

Behavioural plasticity allows organisms to respond to environmental challenges on short time scales. But what are the ecological and evolutionary processes that underlie behavioural plasticity? The answer to this question is complex and requires experimental dissection of the physiological, neural and molecular mechanisms contributing to behavioural plasticity as well as an understanding of the ecological and evolutionary contexts under which behavioural plasticity is adaptive. Here, we discuss key insights that research with Trinidadian guppies has provided on the underpinnings of adaptive behavioural plasticity. First, we present evidence that guppies exhibit contextual, developmental and transgenerational behavioural plasticity. Next, we review work on behavioural plasticity in guppies spanning three ecological contexts (predation, parasitism and turbidity) and three underlying mechanisms (endocrinological, neurobiological and genetic). Finally, we provide three outstanding questions that could leverage guppies further as a study system and give suggestions for how this research could be done. Research on behavioural plasticity in guppies has provided, and will continue to provide, a valuable opportunity to improve understanding of the ecological and evolutionary causes and consequences of behavioural plasticity.

Genetic association with boldness and maternal performance in a free-ranging population of grey seals (Halichoerus grypus).

Individual variation in quantitative traits clearly influence many ecological and evolutionary processes. Moderate to high heritability estimates of personality and life-history traits suggest some level of genetic control over these traits. Yet, we know very little of the underlying genetic architecture of phenotypic variation in the wild. In this study, we used a candidate gene approach to investigate the association of genetic variants with repeated measures of boldness and maternal performance traits (weaning mass and lactation duration) collected over an 11- and 28-year period, respectively, in a free-ranging population of grey seals on Sable Island National Park Reserve, Canada. We isolated and re-sequenced five genes: dopamine receptor D4 (DRD4), serotonin transporter (SERT), oxytocin receptor (OXTR), and melanocortin receptors 1 (MC1R) and 5 (MC5R). We discovered single nucleotide polymorphisms (SNPs) in each gene; and, after accounting for loci in linkage disequilibrium and filtering due to missing data, we were able to test for genotype-phenotype relationships at seven loci in three genes (DRD4, SERT, and MC1R). We tested for association between these loci and traits of 180 females having extreme shy-bold phenotypes using mixed-effects models. One locus within SERT was significantly associated with boldness (effect size = 0.189) and a second locus within DRD4 with weaning mass (effect size = 0.232). Altogether, genotypes explained 6.52-13.66% of total trait variation. Our study substantiates SERT and DRD4 as important determinants of behaviour, and provides unique insight into the molecular mechanisms underlying maternal performance variation in a marine predator.

Natural history study of an understudied sea catfish species from Panama (Siluriformes: Ariidae)

The semi-anadromous sea catfish species Cathorops tuyra (Ariidae, Besudo sea catfish) from the Tropical Eastern Pacific has been found reproductively active in the freshwater rivers and lakes of the Panama Canal. Despite growing concerns for biodiversity, reports on natural history are lacking for many Neotropical sea catfishes. We aimed to provide data on the diet and seasonal timing of spawning of C. tuyra for an autochthonous, semi-anadromous, brackish water population from Rio Santa Maria and an allochthonous freshwater non-migrating population from Rio Chagres, an affluent to the Panama Canal, to understand how changing from semi-anadromous to residential lifestyle affects the natural history of a species. Fish from both sampling sites were dissected and information on stomach content, size, weight, parasitic load, sex, maturity, and number of eggs were recorded. In Rio Chagres, there was a female bias and individuals were larger and in pre-spawning mode compared to Rio Santa Maria. Parasite prevalence was low in Rio Chagres and zero in Rio Santa Maria. The diets were very similar between populations: gastropods, bivalves, and insects were the most important prey items in both rivers representing a diverse omnivorous diet that is similar to that of other catfishes.(AU)

El bagre de mar semi-anádromo Cathorops tuyra (Ariidae, Bagre besudo) del Pacífico Oriental Tropical se encuentra reproductivamente activa en los ríos y lagos del Canal de Panamá. A pesar de la creciente preocupación por la biodiversidad, faltan informes sobre la historia natural de muchos de los bagres Neotropicales. Nuestro objetivo es proporcionar datos básicos sobre la dieta y el momento del desove estacional de C. tuyra para una población autóctona semi-anádroma de agua salobre de Río Santa María y una población alóctona residente de agua dulce de Río Chagres para comprender cómo el cambio de un estilo de vida semi-anádromo a residencial afecta la historia natural de una especie. Se disecaron peces de ambos sitios de muestreo y se registró la información de contenido del estómago, tamaño, peso, carga parasitaria, sexo, madurez y número de huevos. En Río Chagres hubo un sesgo femenino y los individuos eran más grandes y estaban en modo pre-desove que en Río Santa María. La prevalencia de parásitos fue baja en el Río Chagres y cero en Río Santa María. Las dietas fueron muy similares entre poblaciones: gasterópodos, bivalvos e insectos fueron las presas más importantes en ambos ríos, lo que representa una dieta omnívora diversa, que es similar a la de otros bagres.(AU)