Individual differences

Individuals differ. But what environments or conditions select for more or less such individual variation? In black widows, individual differences increase in social (high density) situations, and decrease with disturbance (both effects during development).

Interestingly, differences across multiple axes often come together in ‘syndromes’ (such that a difference in one axis predicts differences in another). For individual social insects, this is studied in the context of division of labor (see section above), although often the syndromes may not conform to classic interpretations (e.g. be more along axes of low vs. high quality workers or lean/old vs fat/young workers).

Groups, or colonies, also differ. We show here that ant colonies vary along a life-history-related syndrome that is driven by nest site competition.

Physiology

Kelemen EP, Cao N, Cao T, Davidowitz G, Dornhaus A 2019 ‘Metabolic rate predicts the lifespan of workers in the bumble bee Bombus impatiens’ Apidologie 50: 195-203 - pdf - in bumble bee workers in the lab, resting metabolic rate measured at emergence explained 17% of variation in lifespan; colony identity explained more, body weight less of the variation; age did not seem to significantly affect resting metabolic rate.

Readers interested in differences in sensory physiology may also want to check out articles on ‘response thresholds’ in the division of labor section.

black widows

Black widows vary in a low vs high investment in foraging (many sticky threads) vs self-defense (better hideout) syndrome; we show that variation among individuals is driven by juvenile experience, and that social environments increase, but disturbance decreases variation.

DiRienzo N, Johnson C, Dornhaus A 2019 'Juvenile social experience generates differences in behavioral variation but not averages', Behavioral Ecology 30: 455–464 - pdf - juvenile experience of high density increases, juvenile experience of disturbance decreases population-level variation in behavior of black widow spiders

DiRienzo N, Schraft HA, Montiglio PO, Bradley CT, Dornhaus A, 2020, ‘Foraging behavior and extended phenotype independently affect foraging success in spiders’, Behavioral Ecology 31, 1242-1249 - pdf - aggressive behavior and number of gumfooted (sticky foraging) silk lines in the web of a black widow spider both and independently increase foraging success

Schraft H, Bilbrey C, Olenski M, DiRienzo N, Montiglio PO, Dornhaus A 2023 Injected serotonin decreases foraging aggression in black widow spiders (Latrodectus hesperus), but dopamine has no effect, Behavioural Processes 204: 104802 - what the title says

DiRienzo N, Bradley CT, Smith CA, Dornhaus A 2019 'Bringing down the house: male widow spiders reduce the webs of aggressive females more' Behavioral Ecology and Sociobiology 73: 1-10 - pdf - males tear down a portion of the females web; this study shows that this probably mostly serves to reduce female cannibalism (instead of signaling or reducing competition from other males)