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Behaviourally specialized foragers are less efficient and live shorter lives than generalists in wasp colonies

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posted on 2021-11-02, 20:51 authored by D Santoro, Stephen HartleyStephen Hartley, Philip LesterPhilip Lester
A widely held assumption in ecology is that specialists are more efficient than generalists. However, empirical evidence for this fundamental assumption is surprisingly scarce and often contradictory. Theoretically, the evolution of alternative life history strategies is underpinned by a trade-off between activity levels and survival. We investigated the consequences of specialization in a foraging context, by comparing the performance and longevity of closely related individuals in a social insect, the common wasp (Vespula vulgaris). Using radio-frequency identification technology, we monitored the lifetime foraging activity of individual wasps from three colonies kept under natural foraging conditions. Returning foragers were video-recorded as they passed the nest entrance so that their foraging load could be assessed. There were substantial differences in foraging activity and survival within and between colonies. At the colony level, foraging specialization was weak. Yet, workers within each nest demonstrated a remarkable range of foraging specialization levels (defined as the degree of overlap between individual and colony-level task allocation) and efficiencies (defined by the number of successful trips and trip duration). We found that specialist foragers were less efficient than generalist siblings within the same colony. Behavioural specialists accomplished fewer successful trips per foraging day, and their trips were typically relatively longer. Specialized foragers also showed reduced life expectancy. The mortality risk was higher for individuals spending relatively more time in the field, yet we found no link between the level of specialization and relative field exposure. Our extensive dataset of unprecedented detail provides strong empirical evidence that behavioural specialization is not associated with a better lifetime performance, on the contrary, the opposite appears true for the common wasp. We also show that the survival of genetically similar individuals can be linked to life-long differences in behaviour according to classical life-history theory predictions.

Funding

Using interaction networks to explain invasion success and community dominance: wasps in an old and new world

Royal Society of New Zealand

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History

Preferred citation

Santoro, D., Hartley, S. & Lester, P. J. (2019). Behaviourally specialized foragers are less efficient and live shorter lives than generalists in wasp colonies. Scientific Reports, 9(1), 5366-. https://doi.org/10.1038/s41598-019-41791-0

Journal title

Scientific Reports

Volume

9

Issue

1

Publication date

2019-12-01

Pagination

5366

Publisher

Springer Science and Business Media LLC

Publication status

Published

Online publication date

2019-03-29

ISSN

2045-2322

eISSN

2045-2322

Article number

5366

Language

en