Individual- and population-level drivers of consistent foraging success across environments

Summary:

Foraging success is an important trait for Darwinian fitness (i.e., the ability to survive and reproduce) that may be constraint by changes in the environment. However, animals may possess behavioural traits that enable them to maintain foraging success under fluctuating environmental conditions. Identifying such traits is important for our understanding of the relationship between the responses of species at the organism level and their overall performance at population and ecosystem levels.

In fishes, assessing the behavioural responses of individuals in their natural environment can be extremely challenging, but guppies inhabiting shallow, isolated pools in a rainforest river provide an ideal system for such studies. Using video equipment and fluorescent color tagging to identify individuals, Snijders et al. assessed the ability of guppies, (Poecilia reticulata) to locate and reach novel food patches in two different natural pools. First, individuals were assessed in batches of 6-8 fish for their ability to forage in one pool and then they were translocated to a second pool where they were assessed again the following day. In addition to foraging success, the authors also assessed sex and proportion of time individuals spend near other individuals (i.e., social tendency).

Findings:

• Individuals that reached more food patches in the first pool also reached more food patches in the second pool.
• More social fish reached more food patches than less social fish.
• Males reached more food patches than females.
• Females appear to compensate for fewer food patches reached by having a higher bit rate than males.

Snijders et al. conclude that individual traits such as sex and social tendency can be important drivers of consistent foraging success across different environments in the wild.

Interest:

I am interested in this preprint because it documents consistency in a performance trait across different environments in the wild as researchers are performing an increasing number of studies on the physiological and behavioural responses of individuals to environmental stressors. Incorporating the results of such studies into ecological species distribution models would be expected to greatly improve the ability of modelers to accurately predict the biogeographic responses of fishes to climate change.

The findings of this study opens up the possibility of running parallel experiments, testing whether the responses of individuals to environmental stressors under controlled laboratory conditions correlates with the responses of individuals to the same stressors in the wild. Studies like these are vital if we are to bridge the gaps between data collected on the responses of fishes to environmental changes at the organism, population and ecosystem levels.

Future directions:

Are there specific constant environmental (elevated temperature, hypoxia, turbidity) or physiological (starvation) conditions under which the observed consistency in foraging success across different natural pools disappear? And are these reproducible in the lab?

Related literature:

JW Brownscombe, SJ Cooke, DA Algera, KC Hanson, EJ Eliason, NJ Burnett, AJ Danylchuk, SG Hinch, AP Farrell (2017). Ecology of exercise in wild fish: Integrating concepts of individual physiological capacity, behavior, and fitness through diverse case studies. Integrative and Comparative Biology 57, 281–292. DOI: 10.1093/icb/icx012

 

Posted on: 17 March 2018

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