1
|
Míčková K, Tomášek O, Jelínek V, Šulc M, Pazdera L, Albrechtová J, Albrecht T. Age-related changes in sperm traits and evidence for aging costs of sperm production in a sexually promiscuous passerine. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1105596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
In many animal species, organismal performance declines with age in a process known as aging or senescence. Senescence typically leads to a deterioration of physiological functionality and can impact the development of primary sexual phenotypes. Sperm production is a complex and costly process that is sensitive to changes in individual physiological state, yet remarkably little is known about age-related changes in sperm performance and aging costs of sperm production. Here we use a non-linear generalized additive mixed models (GAMM) modelling to evaluate age-related changes in postcopulatory sexual traits in the European barn swallow (Hirundo rustica rustica), a relatively short lived sexually promiscuous passerine species, where male extra-pair fertilization success has been shown to increase with age. We confirmed a positive relationship between sperm midpiece length and sperm velocity in this species. Within-male changes in sperm morphology and sperm velocity were in general absent, with only sperm length decreasing linearly with increasing age, although this change was negligible compared to the overall variation in sperm size among males. In contrast, the cloacal protuberance (CP) size changed nonlinearly with age, with an initial increase between the first and third year of life followed by a plateau. The results further indicate the existence of a trade-off between investments in sperm production and survival as males with large CP tended to have a reduced lifespan. This seems consistent with the idea of expensive sperm production and survival aging costs associated with investments in post-copulatory traits in this sexually promiscuous species.
Collapse
|
2
|
Purchase CF, Rooke AC, Gaudry MJ, Treberg JR, Mittell EA, Morrissey MB, Rennie MD. A synthesis of senescence predictions for indeterminate growth, and support from multiple tests in wild lake trout. Proc Biol Sci 2022; 289:20212146. [PMID: 34982951 PMCID: PMC8727146 DOI: 10.1098/rspb.2021.2146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/06/2021] [Indexed: 01/14/2023] Open
Abstract
Senescence-the deterioration of functionality with age-varies widely across taxa in pattern and rate. Insights into why and how this variation occurs are hindered by the predominance of laboratory-focused research on short-lived model species with determinate growth. We synthesize evolutionary theories of senescence, highlight key information gaps and clarify predictions for species with low mortality and variable degrees of indeterminate growth. Lake trout are an ideal species to evaluate predictions in the wild. We monitored individual males from two populations (1976-2017) longitudinally for changes in adult mortality (actuarial senescence) and body condition (proxy for energy balance). A cross-sectional approach (2017) compared young (ages 4-10 years) and old (18-37 years) adults for (i) phenotypic performance in body condition, and semen quality-which is related to fertility under sperm competition (reproductive senescence)-and (ii) relative telomere length (potential proxy for cellular senescence). Adult growth in these particular populations is constrained by a simplified foodweb, and our data support predictions of negligible senescence when maximum size is only slightly larger than maturation size. Negative senescence (aka reverse senescence) may occur in other lake trout populations where diet shifts allow maximum sizes to greatly exceed maturation size.
Collapse
Affiliation(s)
- Craig F. Purchase
- Department of Biology, Memorial University of Newfoundland, St John's, Canada
| | - Anna C. Rooke
- Department of Biology, Memorial University of Newfoundland, St John's, Canada
| | - Michael J. Gaudry
- Department of Biological Sciences, University of Manitoba, Winnipeg, Canada
| | - Jason R. Treberg
- Department of Biological Sciences, University of Manitoba, Winnipeg, Canada
- Centre on Aging, University of Manitoba, Winnipeg, Canada
| | | | | | - Michael D. Rennie
- Department of Biology, Lakehead University, Thunder Bay, Canada
- IISD Experimental Lakes Area, Canada
| |
Collapse
|
3
|
OUP accepted manuscript. Brief Funct Genomics 2022; 21:243-269. [DOI: 10.1093/bfgp/elac007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 11/14/2022] Open
|
4
|
Lemaître JF, Rey B, Gaillard JM, Régis C, Gilot-Fromont E, Débias F, Duhayer J, Pardonnet S, Pellerin M, Haghani A, Zoller JA, Li CZ, Horvath S. DNA methylation as a tool to explore ageing in wild roe deer populations. Mol Ecol Resour 2021; 22:1002-1015. [PMID: 34665921 PMCID: PMC9297961 DOI: 10.1111/1755-0998.13533] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 09/24/2021] [Accepted: 10/11/2021] [Indexed: 12/12/2022]
Abstract
DNA methylation‐based biomarkers of ageing (epigenetic clocks) promise to lead to new insights into evolutionary biology of ageing. Relatively little is known about how the natural environment affects epigenetic ageing effects in wild species. In this study, we took advantage of a unique long‐term (>40 years) longitudinal monitoring of individual roe deer (Capreolus capreolus) living in two wild populations (Chizé and Trois‐Fontaines, France) facing different ecological contexts, to investigate the relationship between chronological age and levels of DNA methylation (DNAm). We generated novel DNA methylation data from n = 94 blood samples, from which we extracted leucocyte DNA, using a custom methylation array (HorvathMammalMethylChip40). We present three DNA methylation‐based estimators of age (DNAm or epigenetic age), which were trained in males, females, and both sexes combined. We investigated how sex differences influenced the relationship between DNAm age and chronological age using sex‐specific epigenetic clocks. Our results highlight that old females may display a lower degree of biological ageing than males. Further, we identify the main sites of epigenetic alteration that have distinct ageing patterns between the two sexes. These findings open the door to promising avenues of research at the crossroads of evolutionary biology and biogerontology.
Collapse
Affiliation(s)
- Jean-François Lemaître
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Benjamin Rey
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Jean-Michel Gaillard
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Corinne Régis
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Emmanuelle Gilot-Fromont
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France.,Université de Lyon, VetAgro Sup, Marcy-l'Etoile, France
| | - François Débias
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Jeanne Duhayer
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Sylvia Pardonnet
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Maryline Pellerin
- Direction de la Recherche et de l'Appui Scientifique, Office Français de la Biodiversité, Unité Ongulés Sauvages, Gap, France
| | - Amin Haghani
- Human Genetics, David Geffen School of Medicine, University of California, Los Angeles California, USA
| | - Joseph A Zoller
- Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, California, USA
| | - Caesar Z Li
- Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, California, USA
| | - Steve Horvath
- Human Genetics, David Geffen School of Medicine, University of California, Los Angeles California, USA.,Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, California, USA
| |
Collapse
|
5
|
Frigerio D, Sumasgutner P, Kotrschal K, Kleindorfer S, Hemetsberger J. From individual to population level: Temperature and snow cover modulate fledging success through breeding phenology in greylag geese (Anser anser). Sci Rep 2021; 11:16100. [PMID: 34373490 PMCID: PMC8352867 DOI: 10.1038/s41598-021-95011-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/19/2021] [Indexed: 11/15/2022] Open
Abstract
Local weather conditions may be used as environmental cues by animals to optimize their breeding behaviour, and could be affected by climate change. We measured associations between climate, breeding phenology, and reproductive output in greylag geese (Anser anser) across 29 years (1990-2018). The birds are individually marked, which allows accurate long-term monitoring of life-history parameters for all pairs within the flock. We had three aims: (1) identify climate patterns at a local scale in Upper Austria, (2) measure the association between climate and greylag goose breeding phenology, and (3) measure the relationship between climate and both clutch size and fledging success. Ambient temperature increased 2 °C across the 29-years study period, and higher winter temperature was associated with earlier onset of egg-laying. Using the hatch-fledge ratio, average annual temperature was the strongest predictor for the proportion of fledged goslings per season. There is evidence for an optimum time window for egg-laying (the earliest and latest eggs laid had the lowest fledging success). These findings broaden our understanding of environmental effects and population-level shifts which could be associated with increased ambient temperature and can thus inform future research about the ecological consequences of climate changes and reproductive output in avian systems.
Collapse
Affiliation(s)
- Didone Frigerio
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Fischerau 11, 4645, Grünau im Almtal, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Petra Sumasgutner
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Fischerau 11, 4645, Grünau im Almtal, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Kurt Kotrschal
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Fischerau 11, 4645, Grünau im Almtal, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Sonia Kleindorfer
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Fischerau 11, 4645, Grünau im Almtal, Austria.
- Department of Behavioral and Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia.
| | - Josef Hemetsberger
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Fischerau 11, 4645, Grünau im Almtal, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| |
Collapse
|
6
|
Heinze J, Giehr J. The plasticity of lifespan in social insects. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190734. [PMID: 33678025 PMCID: PMC7938164 DOI: 10.1098/rstb.2019.0734] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 01/11/2023] Open
Abstract
One of the central questions of ageing research is why lifespans of organisms differ so tremendously among related taxa and, even more surprising, among members of the same species. Social insects provide a particularly pronounced example for this. Here, we review previously published information on lifespan plasticity in social insects and provide new data on worker lifespan in the ant Cardiocondyla obscurior, which because of its relatively short lifespan is a convenient model to study ageing. We show that individual lifespan may vary within species with several reproductive and social traits, such as egg-laying rate, queen number, task, colony size and colony composition. For example, in Cardiocondyla, highly fecund queens live longer than reproductively less active queens, and workers tend to live longer when transferred into a novel social environment or, as we show with new data, into small colonies. We hypothesize that this plasticity of lifespan serves to maximize the reproductive output of the colony as a whole and thus the inclusive fitness of all individuals. The underlying mechanisms that link the social environment or reproductive status with lifespan are currently unresolved. Several studies in honeybees and ants indicate an involvement of nutrient-sensing pathways, but the details appear to differ among species. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'
Collapse
Affiliation(s)
- Jürgen Heinze
- Zoology/Evolutionary Biology, University of Regensburg, Regensburg 93040 Germany
| | - Julia Giehr
- Zoology/Evolutionary Biology, University of Regensburg, Regensburg 93040 Germany
| |
Collapse
|
7
|
Seo AY, Speakman JR, Selman C. Metabolic rate through the life-course: From the organism to the organelle. Exp Gerontol 2020; 140:111059. [PMID: 32853835 DOI: 10.1016/j.exger.2020.111059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Arnold Y Seo
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
| | - John R Speakman
- Center for Energy Metabolism and Reproduction, Shenzhen Institutes of Advanced Technology, Shenzhen, China; Institute of Biological and Environmental Science, University of Aberdeen, Aberdeen AB24 2TZ, UK.
| | - Colin Selman
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
| |
Collapse
|
8
|
Gangloff EJ, Schwartz TS, Klabacka R, Huebschman N, Liu AY, Bronikowski AM. Mitochondria as central characters in a complex narrative: Linking genomics, energetics, pace-of-life, and aging in natural populations of garter snakes. Exp Gerontol 2020; 137:110967. [DOI: 10.1016/j.exger.2020.110967] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 04/11/2020] [Accepted: 05/01/2020] [Indexed: 12/18/2022]
|
9
|
Affiliation(s)
- Jean‐Michel Gaillard
- Laboratoire de Biométrie et Biologie Evolutive UMR5558 CNRS Université Lyon 1 University of Lyon Villeurbanne France
| | - Jean‐François Lemaître
- Laboratoire de Biométrie et Biologie Evolutive UMR5558 CNRS Université Lyon 1 University of Lyon Villeurbanne France
| |
Collapse
|
10
|
Hartmann C, Heinze J, Bernadou A. Age-dependent changes in cuticular color and pteridine levels in a clonal ant. JOURNAL OF INSECT PHYSIOLOGY 2019; 118:103943. [PMID: 31518554 DOI: 10.1016/j.jinsphys.2019.103943] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 06/10/2023]
Abstract
Social insects are emerging models for studying aging and the longevity/fecundity trade-off. Research on the demography of colonies and populations are hampered by the lack of reliable age markers. Here we investigate the suitability of cuticular pigmentation and pteridine fluorescence for age grading individuals of the clonal ant Platythyrea punctata. We found that both traits varied with age. Cuticular color darkened with individual's age until 25-30 days after hatching. For pteridine fluorescence, we found that P. punctata workers show a decrease in head pteridine levels over time until 70-80 days of age. Together with other markers, such as age-based behavior, cuticular coloration and pteridine fluorescence may help to estimate the age structure of colonies.
Collapse
Affiliation(s)
- Clara Hartmann
- Zoology / Evolutionary Biology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany.
| | - Jürgen Heinze
- Zoology / Evolutionary Biology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Abel Bernadou
- Zoology / Evolutionary Biology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| |
Collapse
|
11
|
Giraudeau M, Angelier F, Sepp T. Do Telomeres Influence Pace-of-Life-Strategies in Response to Environmental Conditions Over a Lifetime and Between Generations? Bioessays 2019; 41:e1800162. [DOI: 10.1002/bies.201800162] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/06/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Mathieu Giraudeau
- CREEC; 911 Avenue Agropolis; BP 6450134394 Montpellier Cedex 5 France
- MIVEGEC; UMR IRD/CNRS/UM 5290; 911 Avenue Agropolis, BP 6450134394 Montpellier Cedex 5 France
| | - Frederic Angelier
- CNRS CEBC-ULR; UMR 7372; Villiers en Bois 79360 Beauvoir sur Niort France
| | - Tuul Sepp
- Institute of Ecology and Earth Sciences; University of Tartu; Vanemuise 46 51014 Tartu Estonia
| |
Collapse
|
12
|
Lemaître JF, Gaillard JM. Reproductive senescence: new perspectives in the wild. Biol Rev Camb Philos Soc 2017; 92:2182-2199. [PMID: 28374548 DOI: 10.1111/brv.12328] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/23/2017] [Accepted: 03/03/2017] [Indexed: 11/26/2022]
Abstract
According to recent empirical studies, reproductive senescence, the decline in reproductive success with increasing age, seems to be nearly ubiquitous in the wild. However, a clear understanding of the evolutionary causes and consequences of reproductive senescence is still lacking and requires new and integrative approaches. After identifying the sequential and complex nature of female reproductive senescence, we show that the relative contributions of physiological decline and alterations in the efficiency of parental care to reproductive senescence remain unknown and need to be assessed in the light of current evolutionary theories of ageing. We demonstrate that, although reproductive senescence is generally studied only from the female viewpoint, age-specific female reproductive success strongly depends on male-female interactions. Thus, a reduction in male fertilization efficiency with increasing age has detrimental consequences for female fitness. Lastly, we call for investigations of the role of environmental conditions on reproductive senescence, which could provide salient insights into the underlying sex-specific mechanisms of reproductive success. We suggest that embracing such directions should allow building new bridges between reproductive senescence and the study of sperm competition, parental care, mate choice and environmental conditions.
Collapse
Affiliation(s)
- Jean-François Lemaître
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
| | - Jean-Michel Gaillard
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
| |
Collapse
|
13
|
Urvik J, Meitern R, Rattiste K, Saks L, Hõrak P, Sepp T. Variation in the Markers of Nutritional and Oxidative State in a Long-Lived Seabird: Associations with Age and Longevity. Physiol Biochem Zool 2016; 89:417-40. [PMID: 27617362 DOI: 10.1086/688180] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Age-related declines in life-history traits have been widely observed in free-living animals. Several theories link senescence to oxidative stress. The aim of this study was to measure several widely used markers of oxidative and nutritional state in a long-lived seabird, the common gull (Larus canus), in order to assess the suitability of these markers for describing deterioration in physiological condition associated with chronological age and survival. Associations with longevity and individual consistency of these parameters over the years (repeatability) were also assessed. Senescence in fitness parameters was observed during the study period: in females, laying date and clutch mass were related to bird age in a curvilinear manner, with middle-aged birds breeding earlier and laying heavier eggs. The only parameter associated with aging processes was glutathione concentration in erythrocytes, which was lower in female birds with longer life spans. Of indexes of nutritional state, plasma triglyceride concentration showed a between-individual increase with age, suggesting selective mortality of birds with low levels. Additionally, total plasma protein levels of individual males increased with age. The mostly negative results of this study hint that the commonly used parameters of physiological condition and oxidative state used in this study do not adequately reflect an individual's long-term health condition. Alternatively, it is possible that in common gulls, senescence occurs in reproductive mechanisms but not in mechanisms responsible for maintaining an organism's redox balance, consistent with the idea that different aspects of an organism's physiological condition age at different rates. Significant interannual repeatability was detected in three plasma constituents-carotenoids, uric acid, and total protein-all of which can possibly be linked to variation in dietary habits.
Collapse
|
14
|
Abstract
Lifespan and aging rates vary considerably across taxa; thus, understanding the factors that lead to this variation is a primary goal in biology and has ramifications for understanding constraints and flexibility in human aging. Theory predicts that senescence-declining reproduction and increasing mortality with advancing age-evolves when selection against harmful mutations is weaker at old ages relative to young ages or when selection favors pleiotropic alleles with beneficial effects early in life despite late-life costs. However, in many long-lived ectotherms, selection is expected to remain strong at old ages because reproductive output typically increases with age, which may lead to the evolution of slow or even negligible senescence. We show that, contrary to current thinking, both reproduction and survival decline with adult age in the painted turtle, Chrysemys picta, based on data spanning >20 y from a wild population. Older females, despite relatively high reproductive output, produced eggs with reduced hatching success. Additionally, age-specific mark-recapture analyses revealed increasing mortality with advancing adult age. These findings of reproductive and mortality senescence challenge the contention that chelonians do not age and more generally provide evidence of reduced fitness at old ages in nonmammalian species that exhibit long chronological lifespans.
Collapse
|
15
|
Raubenheimer D, Simpson SJ, Le Couteur DG, Solon-Biet SM, Coogan SCP. Nutritional ecology and the evolution of aging. Exp Gerontol 2016; 86:50-61. [PMID: 27094469 DOI: 10.1016/j.exger.2016.04.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 04/01/2016] [Accepted: 04/07/2016] [Indexed: 11/20/2022]
Abstract
Considerable progress has been made in understanding both evolutionary and mechanistic aspects of biological aging, although the two areas remain poorly integrated. We suggest that a greater emphasis on ecology can help to remedy this, by focusing on the interface between biological mechanisms and the environments in which they evolved by natural selection. Among the most salient aspects of the environment relevant to aging is nutrition, and yet in the bulk of aging research nutrition is coarsely represented as dietary restriction or caloric restriction, without consideration for how specific components of diet, beyond "energy" (the undifferentiated mix of macronutrients), are driving the observed effects. More recently, it has become clear that specific nutrients (notably amino acids) and interactions among nutrients (i.e., nutritional balance) play important roles in the biology of aging. We show how a method developed in nutritional ecology, called the Geometric Framework for nutrition, can help to understand the nutritional interactions of animals with their environments, by explicitly distinguishing the roles of calories, individual nutrients and nutrient balance. Central to these models are the active regulatory responses that animals use to mediate between variation in the nutritional environment and fitness-related consequences such as lifespan and reproduction. These homeostatic responses provide a guide for researchers that can help to link the biological mechanisms with evolutionary processes in the context of a multi-dimensional nutritional environment.
Collapse
Affiliation(s)
- David Raubenheimer
- Charles Perkins Centre, The University of Sydney, NSW, Australia; School of Life and Environmental Sciences, The University of Sydney, NSW, Australia.
| | - Stephen J Simpson
- Charles Perkins Centre, The University of Sydney, NSW, Australia; School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| | - David G Le Couteur
- Charles Perkins Centre, The University of Sydney, NSW, Australia; Ageing and Alzheimers Institute and ANZAC Research Institute, Concord Hospital, Concord 2139, Australia
| | - Samantha M Solon-Biet
- Charles Perkins Centre, The University of Sydney, NSW, Australia; Ageing and Alzheimers Institute and ANZAC Research Institute, Concord Hospital, Concord 2139, Australia
| | - Sean C P Coogan
- Charles Perkins Centre, The University of Sydney, NSW, Australia; School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| |
Collapse
|