Metabolic rate is negatively linked to adult survival but does not explain latitudinal differences in songbirds. (28th January 2020)

• Record Type: Journal Article
• Authors: Boyce, Andy J.; Mouton, James C.; Lloyd, Penn; Wolf, Blair O.; Martin, Thomas E.
• Editors: Norris, Ryan
• Is Part Of: Ecology letters. Volume 23:Number 4(2020)
• Page Start: 642
• Page End: 652
• Publication Date: 2020-01-28
• Subjects: BMR -- demography -- life history -- lifespan -- metabolism -- pace of life -- physiology -- rate of living -- RMR -- senescence; Ecology -- Periodicals; 577
• DOI: 10.1111/ele.13464
• Languages: English
• ISSNs: 1461-023X

Abstract

Abstract: Survival rates vary dramatically among species and predictably across latitudes, but causes of this variation are unclear. The rate‐of‐living hypothesis posits that physiological damage from metabolism causes species with faster metabolic rates to exhibit lower survival rates. However, whether increased survival commonly observed in tropical and south temperate latitudes is associated with slower metabolic rate remains unclear. We compared metabolic rates and annual survival rates that we measured across 46 species, and from literature data across 147 species of birds in northern, southern and tropical latitudes. High metabolic rates were associated with lower survival but survival varied substantially among latitudinal regions independent of metabolism. The inability of metabolic rate to explain latitudinal variation in survival suggests (1) species may evolve physiological mechanisms that mitigate physiological damage from cellular metabolism and (2) extrinsic rather than intrinsic sources of mortality are the primary causes of latitudinal differences in survival. Abstract : The rate of living hypothesis is almost 100 years old, but it remains unclear whether metabolic rate explains global variation in survival rates among closely‐related species. Based on field and literature data from nearly 200 species of songbirds, we find a weak negative relationship between metabolic rate and survival, but large unexplained variation in annual survival across latitudes. This result rejects a longstanding hypothesis and raises the possibility that interspecific variation in longevity is primarily the result of either extrinsic mortality rates or physiological mechanisms to mitigate damage from cellular metabolism.