Developmental Instability and the Environment: Why Are Some Species of Shrews Better Indicators of Stress than Others?

Developmental instability is used commonly to assess environmental conditions, but it is frequently observed that some traits, individuals, and species are better indicators of environmental stress than others. Herein we addressed the mechanisms behind this variation by examining stress-induced developmental instability in three coexisting species of soricid shrews. We examined jaw development in shrews born in areas of extensive logging. We found that for each species, the sensitivity to stress was dependent on co-existence with other shrew species; a species reaction to stress was stronger when other shrew species were present on the study plot. Within species, morphology of the sex which seems to have longer period of growth was more sensitive to stress during development. Finally, on an individual level, sensitivity of different traits to stress was proportional to the degree of their functional integration (i.e., interrelationships due to involvement in the same function); stress-induced variation was confined mostly to functionally independent traits. Thus, variation in behavioral interactions among coexisting related species, duration of growth period, and degree of functional integration should be considered when examining the relationship between developmental instability and environmental change.