Fig. 1. Physiological diversity across levels of organization. Physiological diversity is the result of variation within and among individuals in physiological traits, which can be assessed from the molecular to the organismal level. The extent of variation in physiological traits among individuals (represented here with fish of different shades or sizes) contributes to the physiological diversity of a population. Variation within and among populations contributes to the physiological diversity of species. Variation within and among species contributes to the physiological diversity of a community.
Abstract
Variation in physiological traits can influence the relative resilience of individuals, populations and species of fish to environmental change. Thus, understanding the extent, origins, and consequences of physiological diversity is a key challenge for fish conservation. Physiological diversity within a species can arise as a result of ontogeny, growth, and differences between sexes, and can also be generated by various types of phenotypic plasticity including acclimation, developmental plasticity and transgenerational plasticity. Genetic differences among individuals, populations, and species are also crucial drivers of physiological diversity, and interact with all of the other processes to result in the physiological diversity of living systems. Describing and preserving physiological diversity not only can help target management actions, but also has intrinsic value because high physiological diversity increases ecosystem resilience and influences the capacity for evolutionary adaptation of species to changing environments. However, quantifying the extent of physiological diversity among fishes and assessing its impacts on resilience to environmental change is a daunting task. Despite this, there have already been success stories for fish conservation to date, and taking physiological diversity into account will continue to be critically important for the management and conservation of fish in the Anthropocene.