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McEntee MHF, Foroughirad V, Krzyszczyk E, Mann J. Sex bias in mortality risk changes over the lifespan of bottlenose dolphins. Proc Biol Sci 2023; 290:20230675. [PMID: 37491966 PMCID: PMC10369037 DOI: 10.1098/rspb.2023.0675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/26/2023] [Indexed: 07/27/2023] Open
Abstract
Research on sex biases in longevity in mammals often assumes that male investment in competition results in a female survival advantage that is constant throughout life. We use 35 years of longitudinal data on 1003 wild bottlenose dolphins (Tursiops aduncus) to examine age-specific mortality, demonstrating a time-varying effect of sex on mortality hazard over the five-decade lifespan of a social mammal. Males are at higher risk of mortality than females during the juvenile period, but the gap between male and female mortality hazard closes in the mid-teens, coincident with the onset of female reproduction. Female mortality hazard is non-significantly higher than male mortality hazard in adulthood, resulting in a moderate male bias in the oldest age class. Bottlenose dolphins have an intensely male-competitive mating system, and juvenile male mortality has been linked to social competition. Contrary to predictions from sexual selection theory, however, male-male competition does not result in sustained male-biased mortality. As female dolphins experience high costs of sexual coercion in addition to long and energetically expensive periods of gestation and lactation, this suggests that substantial female investment in reproduction can elevate female mortality risk and impact sex biases in lifespan.
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Affiliation(s)
| | | | - Ewa Krzyszczyk
- Department of Biology, Georgetown University, Washington, DC 20057, USA
- School of Natural Sciences, Bangor University, Bangor, Wales LL57 2DG, UK
| | - Janet Mann
- Department of Biology, Georgetown University, Washington, DC 20057, USA
- Department of Psychology, Georgetown University, Washington, DC 20057, USA
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Schacht R, Beissinger SR, Wedekind C, Jennions MD, Geffroy B, Liker A, Kappeler PM, Weissing FJ, Kramer KL, Hesketh T, Boissier J, Uggla C, Hollingshaus M, Székely T. Adult sex ratios: causes of variation and implications for animal and human societies. Commun Biol 2022; 5:1273. [PMID: 36402823 PMCID: PMC9675760 DOI: 10.1038/s42003-022-04223-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 11/03/2022] [Indexed: 11/21/2022] Open
Abstract
Converging lines of inquiry from across the social and biological sciences target the adult sex ratio (ASR; the proportion of males in the adult population) as a fundamental population-level determinant of behavior. The ASR, which indicates the relative number of potential mates to competitors in a population, frames the selective arena for competition, mate choice, and social interactions. Here we review a growing literature, focusing on methodological developments that sharpen knowledge of the demographic variables underlying ASR variation, experiments that enhance understanding of the consequences of ASR imbalance across societies, and phylogenetic analyses that provide novel insights into social evolution. We additionally highlight areas where research advances are expected to make accelerating contributions across the social sciences, evolutionary biology, and biodiversity conservation.
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Affiliation(s)
- Ryan Schacht
- grid.255364.30000 0001 2191 0423Department of Anthropology, East Carolina University, Greenville, NC USA
| | - Steven R. Beissinger
- grid.47840.3f0000 0001 2181 7878Department of Environmental Science, Policy and Management and Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720 USA
| | - Claus Wedekind
- grid.9851.50000 0001 2165 4204Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Michael D. Jennions
- grid.1001.00000 0001 2180 7477Ecology & Evolution, Research School of Biology, The Australian National University, Acton, Canberra 2601 Australia
| | - Benjamin Geffroy
- MARBEC Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - András Liker
- grid.7336.10000 0001 0203 5854ELKH-PE Evolutionary Ecology Research Group, University of Pannonia, 8210 Veszprém, Hungary ,grid.7336.10000 0001 0203 5854Behavioural Ecology Research Group, Center for Natural Sciences, University of Pannonia, 8210 Veszprém, Hungary
| | - Peter M. Kappeler
- grid.418215.b0000 0000 8502 7018Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute of Primate Biology, 37077 Göttingen, Germany ,grid.7450.60000 0001 2364 4210Department of Sociobiology/Anthropology, University of Göttingen, 37077 Göttingen, Germany
| | - Franz J. Weissing
- grid.4830.f0000 0004 0407 1981Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Karen L. Kramer
- grid.223827.e0000 0001 2193 0096Department of Anthropology, University of Utah, Salt Lake City, UT USA
| | - Therese Hesketh
- grid.83440.3b0000000121901201Institute of Global Health, University College London, London, UK ,grid.13402.340000 0004 1759 700XCentre for Global Health, Zhejiang University School of Medicine, Hangzhou, P.R. China
| | - Jérôme Boissier
- grid.4444.00000 0001 2112 9282IHPE Univ Perpignan Via Domitia, CNRS, Ifremer, Univ Montpellier, Perpignan, France
| | - Caroline Uggla
- grid.10548.380000 0004 1936 9377Stockholm University Demography Unit, Sociology Department, Stockholm University, 106 91 Stockholm, Sweden
| | - Mike Hollingshaus
- grid.223827.e0000 0001 2193 0096Kem C. Gardner Policy Institute, David Eccles School of Business, University of Utah, Salt Lake City, UT USA
| | - Tamás Székely
- grid.7340.00000 0001 2162 1699Milner Centre for Evolution, University of Bath, Bath, BA2 7AY UK ,grid.7122.60000 0001 1088 8582ELKH-DE Reproductive Strategies Research Group, Department of Zoology and Human Biology, University of Debrecen, H-4032 Debrecen, Hungary
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Fojas CL. Abandonment of the Middle Cumberland Region of Tennessee during the Mississippian period: Temporal and sex differences in survivorship. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 177:425-438. [PMID: 36787732 DOI: 10.1002/ajpa.24446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/25/2021] [Accepted: 11/03/2021] [Indexed: 11/08/2022]
Abstract
OBJECTIVES The current research explores survivorship differences in the Middle Cumberland Region of Tennessee during the Mississippian period (ca. 1000-1500 AD). Using updated paleodemographic methods, this study investigates whether individuals from the Late Mississippian period had lower survivorship compared to individuals from the Early Mississippian period, foreshadowing groups on the brink of abandonment. Additionally, this study examines whether there were sex disparities in survivorship. MATERIALS AND METHODS Adult age-at-death estimates from human skeletal remains (n = 545) were calculated using Transition Analysis, a Bayesian maximum likelihood method. Survivorship was reconstructed using Gompertz and Gompertz-Makeham hazards models, with Akaike Information Criterion compared to determine the best fitting model. RESULTS For individuals surviving into adulthood, mean age-at-death decreased by 7 years from the Early Mississippian to Late Mississippian period. Marked differences between the sexes indicate lower survivorship of females compared to males. Male survivorship decreased sharply from the Early Mississippian to Late Mississippian period, from a mean age-at-death of 57.99 years to 44.45 years. Female survivorship remained constant throughout the Mississippian period (41 years). DISCUSSION Temporal differences in male survivorship may be the result of interactions between climate change, decreased maize harvests, and sociopolitical strife. Sustained maternal mortality may have destabilized small-scale communities that characterized the Mississippian MCR, thereby precipitating population decline.
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Affiliation(s)
- Christina L Fojas
- Department of Physical Therapy, Marist College, Poughkeepsie, New York, USA
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Macfarlan SJ, Schacht R, Bourland I, Kapp S, Glad T, Lewis L, Claflin S, Darmiento N, Clegg T, Thorpe C, Peppelar T, Hall RG, Nguyen B, Davis CA, Santiago M, Henrickson C. NDVI predicts birth seasonality in historical Baja California Sur, Mexico: adaptive responses to arid ecosystems and the North American Monsoon. BIODEMOGRAPHY AND SOCIAL BIOLOGY 2021; 66:145-155. [PMID: 34182853 DOI: 10.1080/19485565.2020.1870924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Birth seasonality is a phenomenon whereby populations can be characterized by a single month or season in which births peak. While non-human animal research suggests that seasonal birth-pulses are related to variation in climate and local energy availability, social scientists debate the mechanisms responsible for it in humans. Here we investigate the role of precipitation, temperature, and energy availability on seasonal conception and birth pulses using a historical dataset from the Baja California peninsula - a hot, arid desert that experiences seasonal climatic fluctuations associated with the North American Monsoon. Analyses suggest that 1) local energy availability had a negative relationship with conception pulses; and 2) birth pulses had a positive relationship with local energy availability and a negative relationship with temperature. Taken together, our analyses suggest that women timed conceptions when local energy availability was lowest (challenging expectations of conception rates as simply reflecting ecological influences on female fecundity), so that children were born during the seasonal "green-up" associated with the North American Monsoon. Given our results, we speculate that birth seasonality represents a form of traditional ecological knowledge to improve neonate health and wellbeing.
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Affiliation(s)
- Shane J Macfarlan
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
- Center for Latin American Studies, University of Utah, Salt Lake City, Utah, USA
- Global Change and Sustainability Center, University of Utah, Salt Lake City, Utah, USA
| | - Ryan Schacht
- Department of Anthropology, East Carolina University, Greenville, North Carolina, USA
| | - Izabella Bourland
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
- Environmental and Sustainability Studies, University of Utah, Salt Lake City, Utah, USA
| | - Savannah Kapp
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - Trevor Glad
- Department of Music, University of Utah, Salt Lake City, Utah, USA
| | - Lauren Lewis
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - Spencer Claflin
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - Nathan Darmiento
- Center for Latin American Studies, University of Utah, Salt Lake City, Utah, USA
- Department of History, University of Utah, Salt Lake City, Utah, USA
| | - Tanner Clegg
- College of Humanities, University of Utah, Salt Lake City, Utah, USA
| | - Cole Thorpe
- Center for Latin American Studies, University of Utah, Salt Lake City, Utah, USA
- Department of Linguistics, University of Utah, Salt Lake City, Utah, USA
| | - Taylor Peppelar
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - R Grace Hall
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - Brian Nguyen
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - Connor A Davis
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
| | - Melissa Santiago
- Department of Anthropology, East Carolina University, Greenville, North Carolina, USA
| | - Celeste Henrickson
- Department of Anthropology, University of Utah, Salt Lake City, Utah, USA
- General Education, Nightingale College, Salt Lake City, Utah, USA
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