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Hernández CM, Ellner SP, Snyder RE, Hooker G. The natural history of luck: A synthesis study of structured population models. Ecol Lett 2024; 27:e14390. [PMID: 38549267 DOI: 10.1111/ele.14390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 01/18/2024] [Accepted: 02/08/2024] [Indexed: 04/02/2024]
Abstract
Chance pervades life. In turn, life histories are described by probabilities (e.g. survival and breeding) and averages across individuals (e.g. mean growth rate and age at maturity). In this study, we explored patterns of luck in lifetime outcomes by analysing structured population models for a wide array of plant and animal species. We calculated four response variables: variance and skewness in both lifespan and lifetime reproductive output (LRO), and partitioned them into contributions from different forms of luck. We examined relationships among response variables and a variety of life history traits. We found that variance in lifespan and variance in LRO were positively correlated across taxa, but that variance and skewness were negatively correlated for both lifespan and LRO. The most important life history trait was longevity, which shaped variance and skew in LRO through its effects on variance in lifespan. We found that luck in survival, growth, and fecundity all contributed to variance in LRO, but skew in LRO was overwhelmingly due to survival luck. Rapidly growing populations have larger variances in LRO and lifespan than shrinking populations. Our results indicate that luck-induced genetic drift may be most severe in recovering populations of species with long mature lifespan and high iteroparity.
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Affiliation(s)
- Christina M Hernández
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, USA
| | - Stephen P Ellner
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, USA
| | - Robin E Snyder
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Giles Hooker
- Department of Statistics and Data Science, Cornell University, Ithaca, New York, USA
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Clauss M, Müller DWH. Putting zoo animal cancer into perspective. Zoo Biol 2024; 43:15-21. [PMID: 37664965 DOI: 10.1002/zoo.21802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/30/2023] [Accepted: 08/25/2023] [Indexed: 09/05/2023]
Abstract
As part of a comparative research agenda that promises insights that help extend the human lifespan and combat cancer, cancer prevalence in zoo animals has received recent attention. Here, we want to draw attention to a principle of cancer research that was introduced into the zoo world as early on as 1933, but that seems to have gone somewhat forgotten: Cancer is mainly a disease of old age, and therefore studies aiming at identifying taxa that are particularly susceptible or resistant to cancer must control for whether the respective zoo populations are 'old.' In a comparative context, 'old age' cannot be measured in absolute terms (e.g., years), but only in relation to a species' maximum lifespan: Species that achieve, across zoos, a higher mean lifespan as a percent of their maximum lifespan are 'older.' When applying this metric to former as well as more recently published data on cancer prevalence, it appears that those species that become relatively old in zoos-in particular, the carnivores-have a relatively high cancer prevalence. Any improvement in animal husbandry-which reduces premature deaths-should, by default, lead to more cancer. Cancer in zoo animals, like any other old-age condition, might therefore be embraced as a proxy for good husbandry. Rather than following a sensationalist approach that dramatizes disease and death per se, zoos should be clear about what their husbandry goals are, what relative longevities they want to achieve for which species, and what old-age diseases they should therefore expect: in the end, one has to die of something.
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Affiliation(s)
- Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Veasey JS. In pursuit of peak animal welfare; the need to prioritize the meaningful over the measurable. Zoo Biol 2017; 36:413-425. [PMID: 29193216 DOI: 10.1002/zoo.21390] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/04/2017] [Accepted: 09/29/2017] [Indexed: 11/08/2022]
Abstract
Despite the diversity of animal welfare definitions, most recognise the centrality of the feelings of animals which are currently impossible to measure directly. As a result, animal welfare assessment is heavily reliant upon the indirect measurement of factors that either affect what animals feel, or are effected by how they feel. Physiological and health orientated measures have emerged as popular metrics for assessing welfare because they are quantifiable, can effect and be affected by how animals feel and have merits regardless of their relationship to the feelings of animals. However, their popularity in animal welfare assessment has led to them having a disproportionate influence on animal management to the detriment of animal welfare in numerous instances. Here, the case is made that a tension exists between management that prioritizes aspects of care reflecting popular animal welfare metrics such as those relating to physical health, and management that emphasizes psychological wellbeing. By re-examining the relative merits of physical and psychological priorities in animal management, an alternate animal welfare paradigm emerges less tied to traditional welfare metrics. This paradigm theorizes about the possibility for an optimal animal welfare state to exist where managed animal populations provided essential psychological outlets but protected from key physical stressors routinely experienced in the wild, might experience higher levels of welfare than wild populations would routinely experience. The proposition that optimal animal welfare could theoretically be achieved in well managed and well designed captive environments challenges a widely held ethical perspective that captivity is inherently bad for animal welfare.
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Affiliation(s)
- Jake S Veasey
- Care for the Rare c/o, School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Southwell, United Kingdom
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4
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Ruth Archer C, Basellini U, Hunt J, Simpson SJ, Lee KP, Baudisch A. Diet has independent effects on the pace and shape of aging in Drosophila melanogaster. Biogerontology 2017; 19:1-12. [PMID: 28914388 PMCID: PMC5765211 DOI: 10.1007/s10522-017-9729-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/05/2017] [Indexed: 11/29/2022]
Abstract
Studies examining how diet affects mortality risk over age typically characterise mortality using parameters such as aging rates, which condense how much and how quickly the risk of dying changes over time into a single measure. Demographers have suggested that decoupling the tempo and the magnitude of changing mortality risk may facilitate comparative analyses of mortality trajectories, but it is unclear what biologically meaningful information this approach offers. Here, we determine how the amount and ratio of protein and carbohydrate ingested by female Drosophila melanogaster affects how much mortality risk increases over a time-standardised life-course (the shape of aging) and the tempo at which animals live and die (the pace of aging). We find that pace values increased as flies consumed more carbohydrate but declined with increasing protein consumption. Shape values were independent of protein intake but were lowest in flies consuming ~90 μg of carbohydrate daily. As protein intake only affected the pace of aging, varying protein intake rescaled mortality trajectories (i.e. stretched or compressed survival curves), while varying carbohydrate consumption caused deviation from temporal rescaling (i.e. changed the topography of time-standardised survival curves), by affecting pace and shape. Clearly, the pace and shape of aging may vary independently in response to dietary manipulation. This suggests that there is the potential for pace and shape to evolve independently of one another and respond to different physiological processes. Understanding the mechanisms responsible for independent variation in pace and shape, may offer insight into the factors underlying diverse mortality trajectories.
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Affiliation(s)
- C Ruth Archer
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Treliever Road, Penryn, Cornwall, TR10 9FE, UK. .,MaxNetAging Research School, Max Planck Institute for Demographic Research, Konrad-Zuse-Straße 1, 18057, Rostock, Germany.
| | - Ugofilippo Basellini
- MaxNetAging Research School, Max Planck Institute for Demographic Research, Konrad-Zuse-Straße 1, 18057, Rostock, Germany.,Institut national d'études démographiques (INED), F-75020, Paris, France.,Max-Planck Odense Center on the Biodemography of Aging, Department of Public Health, University of Southern Denmark, J.B. Winsløws Vej 9B, 5000, Odense C, Denmark.,Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense C, Denmark
| | - John Hunt
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Treliever Road, Penryn, Cornwall, TR10 9FE, UK.,School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Stephen J Simpson
- Charles Perkins Centre and School of Life and Environmental Sciences, D17, Charles Perkins Centre Research and Education Hub, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Kwang Pum Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, Republic of Korea
| | - Annette Baudisch
- Max-Planck Odense Center on the Biodemography of Aging, Department of Public Health, University of Southern Denmark, J.B. Winsløws Vej 9B, 5000, Odense C, Denmark.,Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense C, Denmark
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Alroy J. Limits to captive breeding of mammals in zoos. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2015; 29:926-931. [PMID: 25736919 DOI: 10.1111/cobi.12471] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 11/18/2014] [Indexed: 06/04/2023]
Abstract
Captive breeding of mammals in zoos is the last hope for many of the best-known endangered species and has succeeded in saving some from certain extinction. However, the number of managed species selected is relatively small and focused on large-bodied, charismatic mammals that are not necessarily under strong threat and not always good candidates for reintroduction into the wild. Two interrelated and more fundamental questions go unanswered: have the major breeding programs succeeded at the basic level of maintaining and expanding populations, and is there room to expand them? I used published counts of births and deaths from 1970 to 2011 to quantify rates of growth of 118 captive-bred mammalian populations. These rates did not vary with body mass, contrary to strong predictions made in the ecological literature. Most of the larger managed mammalian populations expanded consistently and very few programs failed. However, growth rates have declined dramatically. The decline was predicted by changes in the ratio of the number of individuals within programs to the number of mammal populations held in major zoos. Rates decreased as the ratio of individuals in programs to populations increased. In other words, most of the programs that could exist already do exist. It therefore appears that debates over the general need for captive-breeding programs and the best selection of species are moot. Only a concerted effort could create room to manage a substantially larger number of endangered mammals.
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Affiliation(s)
- John Alroy
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
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Chantepie S, Teplitsky C, Pavard S, Sarrazin F, Descaves B, Lecuyer P, Robert A. Age-related variation and temporal patterns in the survival of a long-lived scavenger. OIKOS 2015. [DOI: 10.1111/oik.02216] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Stéphane Chantepie
- UMR 7204 MNHN-CNRS-UPMC Centre d'Ecologie et des Sciences de la Conservation, Muséum National d'Histoire Naturelle; 55, Rue Buffon FR-75005 Paris France
| | - Céline Teplitsky
- UMR 7204 MNHN-CNRS-UPMC Centre d'Ecologie et des Sciences de la Conservation, Muséum National d'Histoire Naturelle; 55, Rue Buffon FR-75005 Paris France
| | - Samuel Pavard
- UMR7206 MNHN-CNRS-UPD, Musée de l'Homme; 17 place du Trocadero FR-75016 Paris France
| | - François Sarrazin
- UMR 7204 MNHN-CNRS-UPMC Centre d'Ecologie et des Sciences de la Conservation, Muséum National d'Histoire Naturelle; 55, Rue Buffon FR-75005 Paris France
| | | | | | - Alexandre Robert
- UMR 7204 MNHN-CNRS-UPMC Centre d'Ecologie et des Sciences de la Conservation, Muséum National d'Histoire Naturelle; 55, Rue Buffon FR-75005 Paris France
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Robert A, Chantepie S, Pavard S, Sarrazin F, Teplitsky C. Actuarial senescence can increase the risk of extinction of mammal populations. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2015; 25:116-124. [PMID: 26255361 DOI: 10.1890/14-0221.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Despite recent acknowledgement that senescence can have negative impact on survival and fertility in natural environments across a wide range of animal species, we still do not know if it can reduce the viability of wild endangered populations. Focusing on actuarial senescence (i.e., the decline of survival probabilities at old ages), we use species-specific demographic information to project the extinction risk of wild populations of 58 species of mammals, accounting (or not) for senescence. Our projections reveal potential negative effects of aging on population viability, with an average decrease of 27% of the time to extinction and a potential deterioration of the population-level projected conservation status in 10% of the species. Senescence is associated with particularly strong increases of the extinction risk in species with low mortality rates and long intervals between litters, independently of their place in the phylogeny, indicating that the pace of life history can be used to forecast the detrimental effects of aging on the viability of species. The aim of the various existing systems of classification of threatened species is to set conservation priorities based on assessments of extinction risk. Our results indicate that the quantitative effects of senescence on extinction are highly heterogeneous, which can affect the ranking of species and populations when setting conservation, priorities. In mammals, based on life history traits of a few species, generic patterns of senescence can be incorporated into projection population models to minimize these biases in viability assessments.
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