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Isanta‐Navarro J, Prater C, Peoples LM, Loladze I, Phan T, Jeyasingh PD, Church MJ, Kuang Y, Elser JJ. Revisiting the growth rate hypothesis: Towards a holistic stoichiometric understanding of growth. Ecol Lett 2022; 25:2324-2339. [PMID: 36089849 PMCID: PMC9595043 DOI: 10.1111/ele.14096] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/27/2022] [Accepted: 07/31/2022] [Indexed: 01/11/2023]
Abstract
The growth rate hypothesis (GRH) posits that variation in organismal stoichiometry (C:P and N:P ratios) is driven by growth-dependent allocation of P to ribosomal RNA. The GRH has found broad but not uniform support in studies across diverse biota and habitats. We synthesise information on how and why the tripartite growth-RNA-P relationship predicted by the GRH may be uncoupled and outline paths for both theoretical and empirical work needed to broaden the working domain of the GRH. We found strong support for growth to RNA (r2 = 0.59) and RNA-P to P (r2 = 0.63) relationships across taxa, but growth to P relationships were relatively weaker (r2 = 0.09). Together, the GRH was supported in ~50% of studies. Mechanisms behind GRH uncoupling were diverse but could generally be attributed to physiological (P accumulation in non-RNA pools, inactive ribosomes, translation elongation rates and protein turnover rates), ecological (limitation by resources other than P), and evolutionary (adaptation to different nutrient supply regimes) causes. These factors should be accounted for in empirical tests of the GRH and formalised mathematically to facilitate a predictive understanding of growth.
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Affiliation(s)
- Jana Isanta‐Navarro
- Flathead Lake Biological StationUniversity of MontanaPolsonMontanaUSA,Department of BiologyLund UniversityLundSweden
| | - Clay Prater
- Department of Integrative BiologyUniversity of OklahomaStillwaterOklahomaUSA
| | - Logan M. Peoples
- Flathead Lake Biological StationUniversity of MontanaPolsonMontanaUSA
| | - Irakli Loladze
- Bryan College of Health Sciences, Lincoln, NE, USA and School of Mathematical & Statistical SciencesArizona State UniversityTempeArizonaUSA
| | - Tin Phan
- Division of Theoretical Biology and BiophysicsLos Alamos National LaboratoryLos AlamosNew MexicoUSA
| | | | - Matthew J. Church
- Flathead Lake Biological StationUniversity of MontanaPolsonMontanaUSA
| | - Yang Kuang
- School of Life SciencesArizona State UniversityTempeArizonaUSA
| | - James J. Elser
- Flathead Lake Biological StationUniversity of MontanaPolsonMontanaUSA
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Devotta DA, Kent AD, Nelson DM, Walsh PB, Fraterrigo JM, Hu FS. Effects of alder- and salmon-derived nutrients on aquatic bacterial community structure and microbial community metabolism in subarctic lakes. Oecologia 2022; 199:711-724. [PMID: 35739283 DOI: 10.1007/s00442-022-05207-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/21/2022] [Indexed: 12/01/2022]
Abstract
Alder (Alnus spp.) and Pacific salmon (Oncorhynchus spp.) provide key nutrient subsidies to freshwater systems. In southwestern Alaska, alder-derived nutrients (ADNs) are increasing as alder cover expands in response to climate warming, while climate change and habitat degradation are reducing marine-derived nutrients (MDNs) in salmon-spawning habitats. To assess the relative influences of ADN and MDN on aquatic microbial community structure and function, we analyzed lake chemistry, bacterial community structure, and microbial metabolism in 13 lakes with varying alder cover and salmon abundance in southwestern Alaska. We conducted bioassays to determine microbial nutrient limitation and physical factors modulating microbial response to nutrient inputs (+N, +P and +NP treatments). Seasonal shifts in bacterial community structure (F = 7.47, P < 0.01) coincided with changes in lake nitrogen (N) and phosphorus (P) concentrations (r2 = 0.19 and 0.16, both P < 0.05), and putrescine degradation (r2 = 0.13, P = 0.06), suggesting the influx and microbial use of MDN. Higher microbial metabolism occurred in summer than spring, coinciding with salmon runs. Increased microbial metabolism occurred in lakes where more salmon spawned. Microbial metabolic activity was unrelated to alder cover, likely because ADN provides less resource diversity than MDN. When nutrients were added to spring samples, there was greater substrate use by microbial communities from lakes with elevated Chl a concentrations and large relative catchment areas (β estimates for all treatments > 0.56, all P < 0.07). Thus, physical watershed and lake features mediate the effects of nutrient subsidies on aquatic microbial metabolic activity.
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Affiliation(s)
- Denise A Devotta
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Urbana, IL, 61801, USA.
| | - Angela D Kent
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Urbana, IL, 61801, USA.,Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL, 61801, USA
| | - David M Nelson
- Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, MD, 21532, USA
| | - Patrick B Walsh
- Togiak National Wildlife Refuge, U.S. Fish and Wildlife Service, Dillingham, AK, 99576, USA
| | - Jennifer M Fraterrigo
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Urbana, IL, 61801, USA.,Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL, 61801, USA
| | - Feng Sheng Hu
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Urbana, IL, 61801, USA.,Department of Plant Biology, Department of Geology, University of Illinois, Urbana, IL, 61801, USA
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Rizzuto M, Leroux SJ, Vander Wal E, Wiersma YF, Heckford TR, Balluffi‐Fry J. Patterns and potential drivers of intraspecific variability in the body C, N, and P composition of a terrestrial consumer, the snowshoe hare ( Lepus americanus). Ecol Evol 2019; 9:14453-14464. [PMID: 31938532 PMCID: PMC6953652 DOI: 10.1002/ece3.5880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/04/2019] [Accepted: 11/03/2019] [Indexed: 11/09/2022] Open
Abstract
Intraspecific variability in ecological traits is widespread in nature. Recent evidence, mostly from aquatic ecosystems, shows individuals differing at the most fundamental level, that of their chemical composition. Age, sex, or body size and condition may be key drivers of intraspecific variability in the body concentrations of carbon (C), nitrogen (N), and phosphorus (P). However, we still have a rudimentary understanding of the patterns and drivers of intraspecific variability in chemical composition of terrestrial consumers, particularly vertebrates.Here, we investigate the elemental composition of the snowshoe hare Lepus americanus. Based on snowshoe hare ecology, we predicted older, larger individuals to have higher concentration of N or P and lower C content compared with younger, smaller individuals. We also predicted females to have higher concentrations of N, P, and lower C than males due to the higher reproductive costs they incur. Finally, we predicted that individuals in better body condition would have higher N and P than those in worse condition, irrespective of age.We obtained C, N, and P concentrations and ratios from a sample of 50 snowshoe hares. We then used general linear models to test our predictions on the relationship between age, sex, body size or condition and stoichiometric variability in hares.We found considerable variation in C, N, and P stoichiometry within our sample. Contrary to our predictions, we found weak evidence of N content decreasing with age. As well, sex appeared to have no relationship with hare body elemental composition. Conversely, as expected, P content increased with body size and condition. Finally, we found no relationship between variability in C content and any of our predictor variables.Snowshoe hare stoichiometry does not appear to vary with individual age, sex, body size, or condition. However, the weak relationship between body N concentration and age may suggest varying nutritional requirements of individuals at different ages. Conversely, body P's weak relationship to body size and condition appears in line with this limiting element's importance in terrestrial ecosystems. Snowshoe hares are keystone herbivores in the boreal forest of North America, and the substantial stoichiometric variability we find in our sample could have important implications for nutrient dynamics, in both boreal and adjacent ecosystems.
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Affiliation(s)
- Matteo Rizzuto
- Department of BiologyMemorial University of NewfoundlandSt. John'sNFCanada
| | - Shawn J. Leroux
- Department of BiologyMemorial University of NewfoundlandSt. John'sNFCanada
| | - Eric Vander Wal
- Department of BiologyMemorial University of NewfoundlandSt. John'sNFCanada
| | - Yolanda F. Wiersma
- Department of BiologyMemorial University of NewfoundlandSt. John'sNFCanada
| | - Travis R. Heckford
- Department of BiologyMemorial University of NewfoundlandSt. John'sNFCanada
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