1
|
Jiménez R, Burgos M, Barrionuevo FJ. The Biology and Evolution of Fierce Females (Moles and Hyenas). Annu Rev Anim Biosci 2023; 11:141-162. [PMID: 36130099 DOI: 10.1146/annurev-animal-050622-043424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Talpid moles and spotted hyenas have become the paradigms of anatomical and behavioral female masculinization. Females of many mole species develop ovotestes that produce testosterone, show external genitalia that resemble that of males, and close their vaginal orifice after every estrus, and female spotted hyenas lack an external vaginal orifice and develop a pseudoscrotum and a large pseudopenis through which they urinate, mate, and give birth. We review current knowledge about several significant aspects of the biology and evolution of these females, including (a) their specific study methods; (b) their unique anatomical features, and how these peculiarities influence certain physiological functions; and (c) the role that steroid hormones as well as genetic and environmental factors may have in urogenital system development, aggressive behavior, and social dominance. Nevertheless, both mole and hyena females are exceptionally efficient mothers, so their peculiar genitalia should not call into question their femininity.
Collapse
Affiliation(s)
- Rafael Jiménez
- Department of Genetics, Institute of Biotechnology, and Center of Biomedical Research (CIBM), University of Granada, Armilla, Granada, Spain; , ,
| | - Miguel Burgos
- Department of Genetics, Institute of Biotechnology, and Center of Biomedical Research (CIBM), University of Granada, Armilla, Granada, Spain; , ,
| | - Francisco J Barrionuevo
- Department of Genetics, Institute of Biotechnology, and Center of Biomedical Research (CIBM), University of Granada, Armilla, Granada, Spain; , ,
| |
Collapse
|
2
|
Spagnuolo OSB, Lemerle MA, Holekamp KE, Wiesel I. The value of individual identification in studies of free-living hyenas and aardwolves. Mamm Biol 2022; 102:1089-1112. [PMID: 36530605 PMCID: PMC9744671 DOI: 10.1007/s42991-022-00309-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 09/09/2022] [Indexed: 12/15/2022]
Abstract
From population estimates to social evolution, much of our understanding of the family Hyaenidae is drawn from studies of known individuals. The extant species in this family (spotted hyenas, Crocuta crocuta, brown hyenas, Parahyaena brunnea, striped hyenas, Hyaena hyaena, and aardwolves, Proteles cristata) are behaviorally diverse, presenting an equally diverse set of logistical constraints on capturing and marking individuals. All these species are individually identifiable by their coat patterns, providing a useful alternative to man-made markings. Many studies have demonstrated the utility of this method in answering a wide range of research questions across all four species, with some employing a creative fusion of techniques. Despite its pervasiveness in basic research on hyenas and aardwolves, individual identification has rarely been applied to the conservation and management of these species. We argue that individual identification using naturally occurring markings in applied research could prove immensely helpful, as this could further improve accuracy of density estimates, reveal characteristics of suitable habitat, identify threats to population persistence, and help to identify individual problem animals.
Collapse
Affiliation(s)
| | | | | | - Ingrid Wiesel
- Brown Hyena Research Project, Lüderitz, 9000 Namibia
| |
Collapse
|
3
|
Gicquel M, East ML, Hofer H, Benhaiem S. Early-life adversity predicts performance and fitness in a wild social carnivore. J Anim Ecol 2022; 91:2074-2086. [PMID: 35971285 DOI: 10.1111/1365-2656.13785] [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: 11/29/2021] [Accepted: 07/07/2022] [Indexed: 11/30/2022]
Abstract
Studies on humans indicate that encountering multiple sources of adversity in childhood increases the risk of poor long-term health and premature death. Far less is known about cumulative effects of adversity during early life in wildlife. Focusing on the spotted hyena Crocuta crocuta, a social mammal with small litters, extensive maternal care, slow development and access to resources determined by social rank, we determined the contribution of ecological, maternal, social and demographic factors during early life on performance and fitness, and tested whether the impact of early-life adversity is cumulative. Using longitudinal data from 666 female hyenas in the Serengeti National Park, we determined the early growth rate, survival to adulthood, age at first reproduction (AFR), lifetime reproductive success (LRS) and longevity. We fitted multivariate models in which we tested the effects of environmental factors on these performance measures. We then constructed a cumulative adversity index and fitted models to test the effect of this index on each performance measure. Finally, the value of cumulative adversity models was tested by comparing them to multivariate and single-effect models in which the effect of each environmental factor was considered separately. High maternal rank decreased the AFR of daughters. Singleton and dominant cubs had higher growth rate than subordinate cubs, and singletons also had a higher survival chance to adulthood than subordinates. Daughters of prime age mothers had a higher growth rate, longevity and LRS. Little and heavy rainfall decreased survival to adulthood. Increasing numbers of lactating female clan members decreased growth rate, survival to adulthood and LRS. Cumulative adversity negatively affected short-term performance and LRS. Multivariate models outperformed cumulative adversity and single-effect models for all measures except for AFR and longevity, for which single-effect models performed better. Our results suggest that in some wildlife populations the combination of specific conditions in early life may matter more than the accumulation of adverse conditions as such.
Collapse
Affiliation(s)
- Morgane Gicquel
- Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.,Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Marion L East
- Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Heribert Hofer
- Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany.,Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.,Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Sarah Benhaiem
- Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| |
Collapse
|
4
|
McCormick SK, Holekamp KE, Smale L, Weldele ML, Glickman SE, Place NJ. Sex Differences in Spotted Hyenas. Cold Spring Harb Perspect Biol 2022; 14:a039180. [PMID: 34649923 PMCID: PMC9248831 DOI: 10.1101/cshperspect.a039180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The apparent virilization of the female spotted hyena raises questions about sex differences in behavior and morphology. We review these sex differences to find a mosaic of dimorphic traits, some of which conform to mammalian norms. These include space-use, dispersal behavior, sexual behavior, and parental behavior. By contrast, sex differences are reversed from mammalian norms in the hyena's aggressive behavior, social dominance, and territory defense. Androgen exposure early in development appears to enhance aggressiveness in female hyenas. Weapons, hunting behavior, and neonatal body mass do not differ between males and females, but females are slightly larger than males as adults. Sex differences in the hyena's nervous system are relatively subtle. Overall, it appears that the "masculinized" behavioral traits in female spotted hyenas are those, such as aggression, that are essential to ensuring consistent access to food; food critically limits female reproductive success in this species because female spotted hyenas have the highest energetic investment per litter of any mammalian carnivore. Evidently, natural selection has acted to modify traits related to food access, but has left intact those traits that are unrelated to acquiring food, such that they conform to patterns of sexual dimorphism in other mammals.
Collapse
Affiliation(s)
- S Kevin McCormick
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, Michigan 48824, USA
| | - Kay E Holekamp
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, Michigan 48824, USA
| | - Laura Smale
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Psychology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Mary L Weldele
- Departments of Psychology and Integrative Biology, University of California, Berkeley, California 94720, USA
| | - Stephen E Glickman
- Departments of Psychology and Integrative Biology, University of California, Berkeley, California 94720, USA
| | - Ned J Place
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| |
Collapse
|
5
|
Dheer A, Samarasinghe D, Dloniak SM, Braczkowski A. Using camera traps to study hyenas: challenges, opportunities, and outlook. Mamm Biol 2022. [DOI: 10.1007/s42991-021-00188-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractThe use of remote camera traps has accelerated rapidly in the field of large carnivore science since the 1990s. Members of the Hyaenidae are important components of functional ecosystems in Africa and parts of the Middle East and South Asia, and make good candidates for study using camera traps. However, camera trap studies of hyenas remain rare in the literature when compared to species like tigers Panthera tigris, leopards Panthera pardus, and snow leopards Panthera uncia. In this paper, we examine the published use of camera traps for hyenas (n = 34 studies implemented between 2007 and 2020) and examine the logistical challenges of using camera traps, such as individual identification, limited sexual dimorphism, and complex social structures, for studies of hyena population biology, behavioral ecology, and conservation. We highlight what these challenges may mean for data analyses and interpretation. We also suggest potential benefits of further camera trap studies of this taxonomic family, including new insights into social behavior, range extensions, and robust density estimates.
Collapse
|
6
|
Bouffet-Halle A, Yang W, Gardner MG, Whiting MJ, Wapstra E, Uller T, While GM. Characterisation and cross-amplification of sex-specific genetic markers in Australasian Egerniinae lizards and their implications for understanding the evolution of sex determination and social complexity. AUST J ZOOL 2022. [DOI: 10.1071/zo21023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
7
|
Holekamp KE, Strauss ED. Reproduction Within a Hierarchical Society from a Female's Perspective. Integr Comp Biol 2021; 60:753-764. [PMID: 32667986 DOI: 10.1093/icb/icaa068] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The reproductive biology of many female mammals is affected by their social environment and their interactions with conspecifics. In mammalian societies structured by linear dominance hierarchies, such as that of the spotted hyena (Crocuta crocuta), a female's social rank can have profound effects on both her reproductive success and her longevity. In this species, social rank determines priority of access to food, which is the resource limiting reproduction. Due largely to rank-related variation in access to food, reproduction from the perspective of a female spotted hyena can only be understood in the context of her position in the social hierarchy. In this review, we examine the effects of rank on the various phases of reproduction, from mating to weaning. Summed over many individual reproductive lifespans, the effect of rank at these different reproductive phases leads to dramatic rank-related variation in fitness among females and their lineages. Finally, we ask why females reproduce socially despite these apparent costs of group living to low-ranking females. Gregariousness enhances the fitness of females regardless of their positions in the social hierarchy, and females attempting to survive and reproduce without clanmates lose all their offspring. The positive effects of gregariousness appear to result from having female allies, both kin and non-kin, who cooperate to advertise and defend a shared territory, acquire, and defend food resources, maintain the status quo, and occasionally also to rise in social rank.
Collapse
Affiliation(s)
- Kay E Holekamp
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI 48824, USA
| | - Eli D Strauss
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI 48824, USA.,School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| |
Collapse
|
8
|
Turner JW, Robitaille AL, Bills PS, Holekamp KE. Early-life relationships matter: Social position during early life predicts fitness among female spotted hyenas. J Anim Ecol 2020; 90:183-196. [PMID: 32578217 DOI: 10.1111/1365-2656.13282] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 05/20/2020] [Indexed: 12/26/2022]
Abstract
How social development in early-life affects fitness remains poorly understood. Though there is growing evidence that early-life relationships can affect fitness, little research has investigated how social positions develop or whether there are particularly important periods for social position development in an animal's life history. In long-lived species in particular, understanding the lasting consequences of early-life social environments requires detailed, long-term datasets. Here we used a 25-year dataset to test whether social positions held during early development predicted adult fitness. Specifically, we quantified social position using three social network metrics: degree, strength and betweenness. We determined the social position of each individual in three types of networks during each of three stages of ontogeny to test whether they predict annual reproductive success (ARS) or longevity among adult female spotted hyenas Crocuta crocuta. The social positions occupied by juvenile hyenas did predict their fitness, but the effects of social position on fitness measures differed between stages of early development. Network metrics when individuals were young adults better predicted ARS, but network metrics for younger animals, particularly when youngsters were confined to the communal den, better predicted longevity than did metrics assessed during other stages of development. Our study shows how multiple types of social bonds formed during multiple stages of social development predict lifetime fitness outcomes. We suggest that social bonds formed during specific phases of development may be more important than others when considering fitness outcomes.
Collapse
Affiliation(s)
- Julie W Turner
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology, and Behavior, East Lansing, MI, USA.,Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Alec L Robitaille
- Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Patrick S Bills
- Institute for Cyber-Enabled Research, Michigan State University, East Lansing, MI, USA
| | - Kay E Holekamp
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology, and Behavior, East Lansing, MI, USA
| |
Collapse
|
9
|
Yang C, Li F, Xiong Z, Koepfli KP, Ryder O, Perelman P, Li Q, Zhang G. A draft genome assembly of spotted hyena, Crocuta crocuta. Sci Data 2020; 7:126. [PMID: 32345970 PMCID: PMC7189233 DOI: 10.1038/s41597-020-0468-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/31/2020] [Indexed: 11/09/2022] Open
Abstract
The spotted hyena (Crocuta crocuta), one of the largest terrestrial predators native to sub-Saharan Africa, is well known for its matriarchal social system and large-sized social group in which larger females dominate smaller males. Spotted hyenas are highly adaptable predators as they both actively hunt prey and scavenge kills by other predators, and possess an enhanced hypercarnivorous dentition that allows them to crack open bones and thereby feed on nearly all parts of a carcass. Here, we present a high-quality genome assembly of C. crocuta that was generated using a hybrid assembly strategy with Illumina multi-size libraries. A genome of about 2.3 Gb was generated with a scaffold N50 length of 7.2 Mb. More than 35.28% genome region was identified as repetitive elements, and 22,747 protein-coding genes were identified in the genome, with 97.45% of these annotated by databases. This high-quality genome will provide an opportunity to gain insight into the evolution of social behavior and social cognition in mammals, as well as for population genetics and metagenomics studies.
Collapse
Affiliation(s)
- Chentao Yang
- BGI-Shenzhen, Shenzhen, 518083, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, 518120, China
| | - Fang Li
- BGI-Shenzhen, Shenzhen, 518083, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, 518120, China
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Zijun Xiong
- BGI-Shenzhen, Shenzhen, 518083, China
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences (CAS), Kunming, Yunnan, 650223, China
| | - Klaus-Peter Koepfli
- Smithsonian Conservation Biology Institute, Center for Species Survival, National Zoological Park, Front Royal, Virginia 22630 and, Washington, DC, 20008, USA
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State, University, St. Petersburg, 199034, Russia
| | - Oliver Ryder
- San Diego Zoo Institute for Conservation Research, Escondido, CA, 92027, USA
| | - Polina Perelman
- Institute of Molecular and Cellular Biology, Lavrentiev ave. 8/2, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Qiye Li
- BGI-Shenzhen, Shenzhen, 518083, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, 518120, China
| | - Guojie Zhang
- BGI-Shenzhen, Shenzhen, 518083, China.
- China National GeneBank, BGI-Shenzhen, Shenzhen, 518120, China.
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, DK-2100, Copenhagen, Denmark.
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences (CAS), Kunming, Yunnan, 650223, China.
| |
Collapse
|
10
|
Laubach ZM, Faulk CD, Dolinoy DC, Montrose L, Jones TR, Ray D, Pioon MO, Holekamp KE. Early life social and ecological determinants of global DNA methylation in wild spotted hyenas. Mol Ecol 2019; 28:3799-3812. [PMID: 31291495 DOI: 10.1111/mec.15174] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/14/2019] [Accepted: 06/19/2019] [Indexed: 12/26/2022]
Abstract
Environmental factors early in life can have lasting influence on the development and phenotypes of animals, but the underlying molecular modifications remain poorly understood. We examined cross-sectional associations among early life socioecological factors and global DNA methylation in 293 wild spotted hyenas (Crocuta crocuta) in the Masai Mara National Reserve, Kenya, grouped according to three age classes (cub, subadult and adult). Explanatory variables of interest included annual maternal rank based on outcomes of dyadic agonistic interactions, litter size, wild ungulate prey density and anthropogenic disturbance in the year each hyena was born based on counts of illegal livestock in the Reserve. The dependent variable of interest was global DNA methylation, assessed via the LUminometric Methylation Assay, which provides a percentage methylation value calculated at CCGG sites across the genome. Among cubs, we observed approximately 2.75% higher CCGG methylation in offspring born to high- than low-ranking mothers. Among cubs and subadults, higher anthropogenic disturbance corresponded with greater %CCGG methylation. In both cubs and adults, we found an inverse association between prey density measured before a hyena was 3 months old and %CCGG methylation. Our results suggest that maternal rank, anthropogenic disturbance and prey availability early in life are associated with later life global DNA methylation. Future studies are required to understand the extent to which these DNA methylation patterns relate to adult phenotypes and fitness outcomes.
Collapse
Affiliation(s)
- Zachary M Laubach
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.,Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI, USA.,BEACON, NSF Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Mara Hyena Project, Michigan State University, Masai Mara National Reserve, Talek, Kenya
| | | | - Dana C Dolinoy
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA.,Department of Nutritional Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Luke Montrose
- Department of Nutritional Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Tamara R Jones
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Donna Ray
- Divisions of Geriatric Medicine and Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Malit O Pioon
- Mara Hyena Project, Michigan State University, Masai Mara National Reserve, Talek, Kenya
| | - Kay E Holekamp
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.,Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI, USA.,BEACON, NSF Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Mara Hyena Project, Michigan State University, Masai Mara National Reserve, Talek, Kenya
| |
Collapse
|
11
|
Ferreira SCM, Hofer H, Madeira de Carvalho L, East ML. Parasite infections in a social carnivore: Evidence of their fitness consequences and factors modulating infection load. Ecol Evol 2019; 9:8783-8799. [PMID: 31410280 PMCID: PMC6686355 DOI: 10.1002/ece3.5431] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 05/19/2019] [Accepted: 06/08/2019] [Indexed: 01/03/2023] Open
Abstract
There are substantial individual differences in parasite composition and infection load in wildlife populations. Few studies have investigated the factors shaping this heterogeneity in large wild mammals or the impact of parasite infections on Darwinian fitness, particularly in juveniles. A host's parasite composition and infection load can be shaped by factors that determine contact with infective parasite stages and those that determine the host's resistance to infection, such as abiotic and social environmental factors, and age. Host-parasite interactions and synergies between coinfecting parasites may also be important. We test predictions derived from these different processes to investigate factors shaping infection loads (fecal egg/oocyte load) of two energetically costly gastrointestinal parasites: the hookworm Ancylostoma and the intracellular Cystoisospora, in juvenile spotted hyenas (Crocuta crocuta) in the Serengeti National Park, in Tanzania. We also assess whether parasite infections curtail survival to adulthood and longevity. Ancylostoma and Cystoisospora infection loads declined as the number of adult clan members increased, a result consistent with an encounter-reduction effect whereby adults reduced encounters between juveniles and infective larvae, but were not affected by the number of juveniles in a clan. Infection loads decreased with age, possibly because active immune responses to infection improved with age. Differences in parasite load between clans possibly indicate variation in abiotic environmental factors between clan den sites. The survival of juveniles (<365 days old) to adulthood decreased with Ancylostoma load, increased with age, and was modulated by maternal social status. High-ranking individuals with low Ancylostoma loads had a higher survivorship during the first 4 years of life than high-ranking individuals with high Ancylostoma loads. These findings suggest that high infection loads with energetically costly parasites such as hookworms during early life can have negative fitness consequences.
Collapse
Affiliation(s)
| | - Heribert Hofer
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Department of Veterinary MedicineFreie Universität BerlinBerlinGermany
- Department of Biology, Chemistry and PharmacyFreie Universität BerlinBerlinGermany
| | - Luis Madeira de Carvalho
- Centre for Interdisciplinary Research in Animal Health (CIISA), Faculdade de Medicina VeterinariaUniversidade de LisboaLisbonPortugal
| | - Marion L. East
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| |
Collapse
|
12
|
Holekamp KE, Sawdy MA. The evolution of matrilineal social systems in fissiped carnivores. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180065. [PMID: 31303158 DOI: 10.1098/rstb.2018.0065] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We review matrilineal relationships in the societies of fissiped mammalian carnivores, focusing on how the most complex of these may have evolved from simpler systems. Although competition for food is very intense at the trophic level occupied by most carnivores, and although most species of extant fissiped carnivores therefore lead solitary lives, some species show at least rudimentary clustering of maternal kin and matrilineal resource-sharing or transmission of critical resources between generations. The resources shared or transmitted range from individual food items and territories to entire networks of potential allies. The greatest elaboration of matrilineal relationships has occurred in two large carnivores, lions and spotted hyenas, which occur sympatrically throughout much of Africa. The societies of both these species apparently evolved in response to a shared suite of ecological conditions. The highly matrilineal societies of spotted hyenas are unique among carnivores and closely resemble the societies of many cercopithecine primates. The conditions favouring the evolution of matrilineal societies in carnivores include male-biased dispersal, female philopatry, the need for assistance in protecting or provisioning offspring, reliance on large or abundant prey, particularly in open habitat, high population density and kin-structured cooperative interactions that have strong positive effects on fitness. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.
Collapse
Affiliation(s)
- Kay E Holekamp
- 1 Department of Integrative Biology, Michigan State University , East Lansing, MI , USA.,2 Program in Ecology, Evolutionary Biology and Behavior, Michigan State University , East Lansing, MI , USA
| | - Maggie A Sawdy
- 1 Department of Integrative Biology, Michigan State University , East Lansing, MI , USA.,2 Program in Ecology, Evolutionary Biology and Behavior, Michigan State University , East Lansing, MI , USA
| |
Collapse
|
13
|
Defreyne J, Kreukels B, T'Sjoen G, Staphorsius A, Den Heijer M, Heylens G, Elaut E. No correlation between serum testosterone levels and state-level anger intensity in transgender people: Results from the European Network for the Investigation of Gender Incongruence. Horm Behav 2019; 110:29-39. [PMID: 30822410 DOI: 10.1016/j.yhbeh.2019.02.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/25/2019] [Accepted: 02/25/2019] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Anger is a state of emotions ranging from irritation to intense rage. Aggression implies externalizing anger through destructive/punitive behaviour. The World Professional Association for Transgender Health (WPATH) Standards of Care, Edition 7 (SOC7) guidelines warn about aggression in transgender men (TM) on testosterone treatment. We aimed to assess whether anger intensity increases in TM and decreases in transgender women (TW) after initiation of gender affirming hormone therapy and to identify predictors for anger intensity in transgender people. METHODS This prospective cohort study was part of the European Network for the Investigation of Gender Incongruence (ENIGI). Anger intensity was prospectively assessed in 898 participants (440 TM, 468 TW) by STAXI-2 (State-Trait Anger Expression Inventory-2) State Anger (S-Anger) during a three-year follow-up period, starting at the initiation of hormone treatment. Data were analysed cross-sectionally and prospectively. RESULTS There was no change in STAXI-2 S-Anger scores. At three, twelve and thirty-six months of gender affirming hormone therapy, STAXI-2 S-Anger scores were not correlated to serum testosterone levels, although there was a correlation with various psychological measures after three and twelve months. TM experiencing menstrual spotting after three months had higher STAXI-2 S-Anger scores compared to those without (median 26.5 [18.0-29.8] versus 15.0 [15.0-17.0], P = 0.020). Changes in STAXI-2 S-Anger scores were not correlated to changes in serum testosterone levels after three, twelve and thirty-six months in TM or TW. CONCLUSIONS State-level anger intensity is associated with psychological and/or psychiatric vulnerability, but not exogenous testosterone therapy or serum testosterone levels in transgender people.
Collapse
Affiliation(s)
- Justine Defreyne
- Ghent University Hospital, Department of Endocrinology, C. Heymanslaan 10, 9000 Ghent, Belgium.
| | - Baudewijntje Kreukels
- Amsterdam University Medical Center, VUmc, Department of Psychology and Center of Expertise on Gender Dysphoria, De Boelelaan 1117, 1081 HV Amsterdam, the Netherlands
| | - Guy T'Sjoen
- Ghent University Hospital, Department of Endocrinology and Center for Sexology and Gender, De Pintelaan 185, 9000 Ghent, Belgium
| | - Annemieke Staphorsius
- Amsterdam University Medical Center, VUmc, Department of Endocrinology and Center of Expertise on Gender Dysphoria, De Boelelaan 1117, 1081 HV Amsterdam, the Netherlands
| | - Martin Den Heijer
- Amsterdam University Medical Center, VUmc, Department of Endocrinology and Center of Expertise on Gender Dysphoria, De Boelelaan 1117, 1081 HV Amsterdam, the Netherlands
| | - Gunter Heylens
- Ghent University Hospital, Center for Sexology and Gender, C. Heymanslaan 10, 9000 Ghent, Belgium
| | - Els Elaut
- Ghent University Hospital, Center for Sexology and Gender, C. Heymanslaan 10, 9000 Ghent, Belgium
| |
Collapse
|
14
|
Is play a behavior system, and, if so, what kind? Behav Processes 2019; 160:1-9. [DOI: 10.1016/j.beproc.2018.12.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 12/29/2022]
|
15
|
Heaver J, Waters M. A retrospective study of mortality in Eurasian lynx (Lynx lynx) in UK zoos. Zoo Biol 2019; 38:200-208. [PMID: 30672008 PMCID: PMC6850182 DOI: 10.1002/zoo.21476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 11/18/2018] [Accepted: 12/14/2018] [Indexed: 11/07/2022]
Abstract
IUCN currently classifies the Eurasian lynx (Lynx lynx) as “Least Concern,” however, across its six to nine subspecies, some isolated populations are classified as “Endangered” or “Critically Endangered.” Despite this and the species’ relative ubiquity in European zoos, a retrospective mortality study of a captive population has not previously been performed. By analyzing necropsy reports, animal records, and the European studbook, we were able to ascertain a cause of death for 38 (73%) of the 52 recorded lynx deaths in UK zoos during the study period (January 1, 2000 to November 1, 2015). “Culling” as part of population management was the most common cause of death (21%) followed by neoplastic (16%), circulatory (11%), neurological (11%), and genitourinary (11%) disease. “Geriatric” individuals accounted for 62% of lynx to die within the study period, 23% were “neonates” and 15% “adults.” Neoplasia, circulatory disease, and culling were the leading causes of death in each of these age categories, respectively. Excluding “culls” and “neonates,” the mean age at death was 18.81 ± 0.42 years, consistent with existing data. Squamous cell carcinoma was reported in three individuals (8%) and suspected idiopathic epilepsy in four individuals (11%), warranting further investigation. Intraspecific killing (3%) and neonatal mortality, excluding culls, (14%) were reported with lower prevalence than expected based on previous studies of similar species. The lack of data available and high incidence of culling of individuals with a high inbreeding coefficient highlights the need for improved record‐keeping and consultation with the studbook coordinator, respectively.
Collapse
Affiliation(s)
- Joseph Heaver
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, UK
| | - Michael Waters
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, UK
| |
Collapse
|
16
|
Social support drives female dominance in the spotted hyaena. Nat Ecol Evol 2018; 3:71-76. [DOI: 10.1038/s41559-018-0718-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 10/11/2018] [Indexed: 11/08/2022]
|
17
|
Marescot L, Benhaiem S, Gimenez O, Hofer H, Lebreton J, Olarte‐Castillo XA, Kramer‐Schadt S, East ML. Social status mediates the fitness costs of infection with canine distemper virus in Serengeti spotted hyenas. Funct Ecol 2018; 32:1237-1250. [PMID: 32313354 PMCID: PMC7163977 DOI: 10.1111/1365-2435.13059] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 01/26/2018] [Indexed: 02/06/2023]
Abstract
The extent to which the fitness costs of infection are mediated by key life-history traits such as age or social status is still unclear. Within populations, individual heterogeneity in the outcome of infection is the result of two successive processes; the degree of contact with the pathogen (exposure) and the immune response to infection. In social mammals, because individuals holding high social status typically interact more frequently with group members, they should be more often in contact with infected individuals than those of low social status. However, when access to resources is determined by social status, individuals with a high social status are often better nourished, have a greater opportunity to allocate resources to immune processes and therefore should have a smaller chance of succumbing to infection than individuals with low social status.We investigated the risk and fitness costs of infection during a virulent epidemic of canine distemper virus (CDV) in a social carnivore, the spotted hyena, in the Serengeti National Park. We analysed two decades of detailed life-history data from 625 females and 816 males using a multi-event capture-mark-recapture model that accounts for uncertainty in the assignment of individual infection states.Cubs of mothers with a high social status had a lower probability of CDV infection and were more likely to survive infection than those with low social status. Subadult and adult females with high social status had a higher infection probability than those with low social status. Subadult females and pre-breeder males that had recovered from CDV infection had a lower survival than susceptible ones.Our study disentangles the relative importance of individual exposure and resource allocation to immune processes, demonstrates fitness costs of infection for juveniles, particularly for those with low social status, shows that patterns of infection can be driven by different mechanisms among juveniles and adults and establishes a negative relationship between infection and fitness in a free-ranging mammal. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13059/suppinfo is available for this article.
Collapse
Affiliation(s)
- Lucile Marescot
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Sarah Benhaiem
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Olivier Gimenez
- CEFEUMR 5175CNRSUniversité de MontpellierUniversité Paul‐Valéry MontpellierEPHEMontpellier Cedex 5France
| | - Heribert Hofer
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Department of Veterinary MedicineFreie Universität BerlinBerlinGermany
- Department of Biology, Chemistry, PharmacyFreie Universität BerlinBerlinGermany
| | - Jean‐Dominique Lebreton
- CEFEUMR 5175CNRSUniversité de MontpellierUniversité Paul‐Valéry MontpellierEPHEMontpellier Cedex 5France
| | | | - Stephanie Kramer‐Schadt
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Marion L. East
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| |
Collapse
|
18
|
Prospective Evaluation of Self-Reported Aggression in Transgender Persons. J Sex Med 2018; 15:768-776. [DOI: 10.1016/j.jsxm.2018.03.079] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 03/21/2018] [Accepted: 03/21/2018] [Indexed: 11/23/2022]
|
19
|
Turner JW, Bills PS, Holekamp KE. Ontogenetic change in determinants of social network position in the spotted hyena. Behav Ecol Sociobiol 2017. [DOI: 10.1007/s00265-017-2426-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
20
|
Unusually high-pitched neonate distress calls of the open-habitat Mongolian gazelle (Procapra gutturosa) and their anatomical and hormonal predictors. Naturwissenschaften 2017; 104:50. [PMID: 28578533 DOI: 10.1007/s00114-017-1471-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 12/25/2022]
Abstract
In neonate ruminants, the acoustic structure of vocalizations may depend on sex, vocal anatomy, hormonal profiles and body mass and on environmental factors. In neonate wild-living Mongolian gazelles Procapra gutturosa, hand-captured during biomedical monitoring in the Daurian steppes at the Russian-Mongolian border, we spectrographically analysed distress calls and measured body mass of 22 individuals (6 males, 16 females). For 20 (5 male, 15 female) of these individuals, serum testosterone levels were also analysed. In addition, we measured relevant dimensions of the vocal apparatus (larynx, vocal folds, vocal tract) in one stillborn male Mongolian gazelle specimen. Neonate distress calls of either sex were high in maximum fundamental frequency (800-900 Hz), but the beginning and minimum fundamental frequencies were significantly lower in males than in females. Body mass was larger in males than in females. The levels of serum testosterone were marginally higher in males. No correlations were found between either body mass or serum testosterone values and any acoustic variable for males and females analysed together or separately. We discuss that the high-frequency calls of neonate Mongolian gazelles are more typical for closed-habitat neonate ruminants, whereas other open-habitat neonate ruminants (goitred gazelle Gazella subgutturosa, saiga antelope Saiga tatarica and reindeer Rangifer tarandus) produce low-frequency (<200 Hz) distress calls. Proximate cause for the high fundamental frequency of distress calls of neonate Mongolian gazelles is their very short, atypical vocal folds (4 mm) compared to the 7-mm vocal folds of neonate goitred gazelles, producing distress calls as low as 120 Hz.
Collapse
|
21
|
Sharpe LL, Rubow J, Cherry MI. Robbing rivals: interference foraging competition reflects female reproductive competition in a cooperative mammal. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2015.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
22
|
Petty JMA, Drea CM. Female rule in lemurs is ancestral and hormonally mediated. Sci Rep 2015; 5:9631. [PMID: 25950904 PMCID: PMC4423346 DOI: 10.1038/srep09631] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/20/2015] [Indexed: 11/26/2022] Open
Abstract
Female social dominance (FSD) over males is unusual in mammals, yet characterizes most Malagasy lemurs, which represent almost 30% of all primates. Despite its prevalence in this suborder, both the evolutionary trajectory and proximate mechanism of FSD remain unclear. Potentially associated with FSD is a suite of behavioural, physiological and morphological traits in females that implicates (as a putative mechanism) 'masculinization' via androgen exposure; however, relative to conspecific males, female lemurs curiously show little evidence of raised androgen concentrations. By observing mixed-sex pairs of related Eulemur species, we identified two key study groups--one comprised of species expressing FSD and increased female scent marking, the other comprised of species (from a recently evolved clade) showing equal status between the sexes and the more traditional pattern of sexually dimorphic behaviour. Comparing females from these two groups, we show that FSD is associated with more masculine androgen profiles. Based on the widespread prevalence of male-like features in female lemurs and a current phylogeny, we suggest that relaxation of hormonally mediated FSD emerged only recently and that female masculinization may be the ancestral lemur condition, an idea that could revolutionize our understanding of the ancient socioecology and evolution of primate social systems.
Collapse
Affiliation(s)
- Joseph M. A. Petty
- University Program in Ecology, Duke University, Durham, NC 27708 USA
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708 USA
| | - Christine M. Drea
- University Program in Ecology, Duke University, Durham, NC 27708 USA
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708 USA
- Department of Biology, Duke University, Durham, NC 27708 USA
| |
Collapse
|
23
|
Attunement to the fertility status of same-sex rivals: women's testosterone responses to olfactory ovulation cues. EVOL HUM BEHAV 2013. [DOI: 10.1016/j.evolhumbehav.2013.07.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
24
|
French JA, Mustoe AC, Cavanaugh J, Birnie AK. The influence of androgenic steroid hormones on female aggression in 'atypical' mammals. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130084. [PMID: 24167314 PMCID: PMC3826213 DOI: 10.1098/rstb.2013.0084] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dimorphism on dominance and agonistic behaviour in mammals tends to be strongly biased toward males. In this review, we focus on a select few species of mammals in which females are as or more aggressive than males, and/or are dominant to males, and explore the role of androgenic hormones in mediating this important difference. While the data are not as clear-cut as those published on traditional laboratory mammals, our review highlights important endocrine substrates for both organizational and activational influences of steroids on female aggressive behaviour. We highlight areas in which further observations and experiments are crucial, especially the potential facilitative effects of androgens on female aggression. Finally, new and innovative techniques, including molecular genetics and receptor pharmacology, portend important insights into the ways in which androgenic hormones regulate aggressive behaviour in 'atypical' female mammals.
Collapse
Affiliation(s)
- Jeffrey A. French
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
- Department of Biology, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Aaryn C. Mustoe
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Jon Cavanaugh
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Andrew K. Birnie
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
| |
Collapse
|
25
|
Benhaiem S, Hofer H, Kramer-Schadt S, Brunner E, East ML. Sibling rivalry: training effects, emergence of dominance and incomplete control. Proc Biol Sci 2012; 279:3727-35. [PMID: 22719032 DOI: 10.1098/rspb.2012.0925] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Within-brood or -litter dominance provides fitness-related benefits if dominant siblings selfishly skew access to food provided by parents in their favour. Models of facultative siblicide assume that dominants exert complete control over their subordinate sibling's access to food and that control is maintained, irrespective of the subordinate's hunger level. By contrast, a recent functional hypothesis suggests that subordinates should contest access to food when the cost of not doing so is high. Here, we show that within spotted hyena (Crocuta crocuta) twin litters, dominants most effectively skew access to maternal milk in their favour when their aggression prompts a highly submissive response. When hungry, subordinates were less submissive in response to aggression, thereby decreasing lost suckling time and increasing suckling time lost by dominants. In a species where adult females socially dominate adult males, juvenile females were more often dominant than males in mixed-sex litters, and subordinate sisters used more effective counter-tactics against dominant brothers than subordinate brothers against dominant sisters. Our results provide, to our knowledge, the first evidence in a mammal that dominant offspring in twin litters do not exert complete control over their sibling's access to resources (milk), and that sibling dominance relationships are influenced by sibling sex and training effects.
Collapse
Affiliation(s)
- Sarah Benhaiem
- Leibniz Institute for Zoo and Wildlife Research, 10315 Berlin, Germany.
| | | | | | | | | |
Collapse
|
26
|
Andersen IL, Nævdal E, Bøe KE. Maternal investment, sibling competition, and offspring survival with increasing litter size and parity in pigs (Sus scrofa). Behav Ecol Sociobiol 2011; 65:1159-1167. [PMID: 21743767 PMCID: PMC3096772 DOI: 10.1007/s00265-010-1128-4] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 11/17/2010] [Accepted: 11/24/2010] [Indexed: 11/24/2022]
Abstract
The aim of this study was to examine the effects of litter size and parity on sibling competition, piglet survival, and weight gain. It was predicted that competition for teats would increase with increasing litter size, resulting in a higher mortality due to maternal infanticide (i.e., crushing) and starvation, thus keeping the number of surviving piglets constant. We predicted negative effects on weight gain with increasing litter size. Based on maternal investment theory, we also predicted that piglet mortality would be higher for litters born late in a sow's life and thus that the number of surviving piglets would be higher in early litters. As predicted, piglet mortality increased with increasing litter size both due to an increased proportion of crushed piglets, where most of them failed in the teat competition, and due to starvation caused by increased sibling competition, resulting in a constant number of survivors. Piglet weight at day 1 and growth until weaning also declined with increasing litter size. Sows in parity four had higher piglet mortality due to starvation, but the number of surviving piglets was not affected by parity. In conclusion, piglet mortality caused by maternal crushing of piglets, many of which had no teat success, and starvation caused by sibling competition, increased with increasing litter size for most sow parities. The constant number of surviving piglets at the time of weaning suggests that 10 to 11 piglets could be close to the upper limit that the domestic sow is capable of taking care of.
Collapse
Affiliation(s)
- Inger Lise Andersen
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Eric Nævdal
- Frisch Centre, Gaustadalléen 21, 0349 Oslo, Norway
| | - Knut Egil Bøe
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| |
Collapse
|
27
|
Holekamp KE, Dloniak SM. Intraspecific Variation in the Behavioral Ecology of a Tropical Carnivore, the Spotted Hyena. ADVANCES IN THE STUDY OF BEHAVIOR 2010. [DOI: 10.1016/s0065-3454(10)42006-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
|
28
|
Rice WR, Gavrilets S, Friberg U. Sexually antagonistic chromosomal cuckoos. Biol Lett 2009; 5:686-8. [PMID: 19364719 PMCID: PMC2781942 DOI: 10.1098/rsbl.2009.0061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 03/16/2009] [Indexed: 11/12/2022] Open
Abstract
The two kinds of sex chromosomes in the heterogametic parent are transmitted to offspring with different sexes, causing opposite-sex siblings to be completely unrelated for genes located on these chromosomes. Just as the nest-parasitic cuckoo chick is selected to harm its unrelated nest-mates in order to garner more shared resources, sibling competition causes the sex chromosomes to be selected to harm siblings that do not carry them. Here we quantify and contrast this selection on the X and Y, or Z and W, sex chromosomes. We also develop a hypothesis for how this selection can contribute to the decay of the non-recombining sex chromosome.
Collapse
Affiliation(s)
- William R Rice
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA.
| | | | | |
Collapse
|
29
|
Hodge S, Thornton A, Flower T, Clutton-Brock T. Food limitation increases aggression in juvenile meerkats. Behav Ecol 2009. [DOI: 10.1093/beheco/arp071] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
30
|
Frankand LG, Glickman SE. Giving birth through a penile clitoris: parturition and dystocia in the spotted hyaena (Crocuta crocuta). J Zool (1987) 2009. [DOI: 10.1111/j.1469-7998.1994.tb04871.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
31
|
The rarity of twins: a result of an evolutionary battle between mothers and daughters—or do they agree? Behav Ecol Sociobiol 2009. [DOI: 10.1007/s00265-009-0745-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
32
|
McFadden D. Masculinization of the mammalian cochlea. Hear Res 2009; 252:37-48. [PMID: 19272340 DOI: 10.1016/j.heares.2009.01.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 01/08/2009] [Accepted: 01/12/2009] [Indexed: 11/30/2022]
Abstract
Otoacoustic emissions (OAEs) differ between the sexes in humans, rhesus and marmoset monkeys, and sheep. OAEs also are different in a number of special populations of humans. Those basic findings are reviewed and discussed in the context of possible prenatal-androgen effects on the auditory system. A parsimonious explanation for several outcomes is that prenatal exposure to high levels of androgens can weaken the cochlear amplifiers and thereby weaken otoacoustic emissions (OAEs). Prenatal androgen exposure apparently also can alter auditory evoked potentials (AEPs). Some non-hormonal factors possibly capable of producing sex and group differences are discussed, and some speculations are offered about specific cochlear structures that might differ between the two sexes.
Collapse
Affiliation(s)
- Dennis McFadden
- Department of Psychology and Center for Perceptual Systems, University of Texas at Austin, Seay Building, 1 University Station, A8000, Austin, TX 78712-0187, USA.
| |
Collapse
|
33
|
McFadden D, Pasanen EG, Valero MD, Roberts EK, Lee TM. Effect of prenatal androgens on click-evoked otoacoustic emissions in male and female sheep (Ovis aries). Horm Behav 2009; 55:98-105. [PMID: 18834887 PMCID: PMC2649662 DOI: 10.1016/j.yhbeh.2008.08.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 07/31/2008] [Accepted: 08/26/2008] [Indexed: 11/24/2022]
Abstract
Otoacoustic emissions (OAEs) were measured in male and female Suffolk sheep (Ovis aries). Some sheep had been administered androgens or estrogens during prenatal development, some were gonadectomized after birth, and some were allowed to develop normally. As previously reported for spotted hyenas, gonadectomy did not alter the OAEs for either sex; accordingly, the untreated/intact and the untreated/gonadectomized animals were pooled to form the control groups. The click-evoked otoacoustic emissions (CEOAEs) exhibited by the female control group (N=12) were slightly stronger (effect size=0.42) than those in the male control group (N=15), which is the same direction of effect reported for humans and rhesus monkeys. Females administered testosterone prenatally (N=16) had substantially weaker (masculinized) CEOAEs than control females (effect size=1.15). Both of these outcomes are in accord with the idea that prenatal exposure to androgens weakens the cochlear mechanisms that underlie the production of OAEs. The CEOAEs of males administered testosterone prenatally (N=5) were not different from those of control males, an outcome also seen in similarly treated rhesus monkeys. Males administered dihydrotestosterone (DHT) prenatally (N=3) had slightly stronger (hypo-masculinized) CEOAEs than control males. No spontaneous otoacoustic emissions (SOAEs) were found in any ears, a common finding in non-human species. To our knowledge, this is the first ruminant species measured for OAEs.
Collapse
Affiliation(s)
- Dennis McFadden
- Department of Psychology and Center for Perceptual Systems, University of Texas at Austin, 1 University Station A8000, Austin, TX 78712-0187, USA.
| | | | | | | | | |
Collapse
|
34
|
McFadden D. What Do Sex, Twins, Spotted Hyenas, ADHD, and Sexual Orientation Have in Common? PERSPECTIVES ON PSYCHOLOGICAL SCIENCE 2008; 3:309-23. [DOI: 10.1111/j.1745-6924.2008.00082.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The otoacoustic emissions (OAEs) measured in a collection of special populations of humans and certain nonhuman species suggest that OAEs may provide a window into some processes of human prenatal development and sexual differentiation. For reasons that are unclear, OAEs appear to be highly sensitive to events occurring during prenatal development that seem to be related to the degree of exposure to androgens a fetus receives. The (largely circumstantial) evidence for a relationship between androgen exposure and OAE strength comes from a series of studies of twins, children with attention-deficit/hyperactivity disorder, people of differing sexual orientations, and spotted hyenas, among others. Some conclusions are bolstered by parallel studies using auditory evoked potentials (AEPs). OAEs and AEPs are simple, objective, noninvasive measures that appear to have potential as tools of value to researchers working on a wide variety of basic and applied topics beyond audition.
Collapse
Affiliation(s)
- Dennis McFadden
- Department of Psychology and Center for Perceptual Systems, University of Texas
| |
Collapse
|
35
|
BIKNEVICIUS AUDRONER, LEIGH STEVENR. Patterns of growth of the mandibular corpus in spotted hyenas (Crocuta crocuta) and cougars (Puma concolor). Zool J Linn Soc 2008. [DOI: 10.1111/j.1096-3642.1997.tb01276.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
36
|
Raihani NJ, Ridley AR, Browning LE, Nelson-Flower MJ, Knowles S. Juvenile Female Aggression in Cooperatively Breeding Pied Babblers: Causes and Contexts. Ethology 2008. [DOI: 10.1111/j.1439-0310.2008.01482.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
37
|
Rödel HG, Hudson R, von Holst D. Optimal litter size for individual growth of European rabbit pups depends on their thermal environment. Oecologia 2008; 155:677-89. [DOI: 10.1007/s00442-008-0958-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 12/19/2007] [Indexed: 11/29/2022]
|
38
|
Naidenko SV, Antonevich AL, Erofeeva MN. Hormonal response to a synthetic analog of adrenocorticotropic hormone in lynx pups (Lynx lynx L.). DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2007; 416:341-4. [PMID: 18047013 DOI: 10.1134/s0012496607050055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- S V Naidenko
- Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninskii pr. 33, Moscow, 117071 Russia
| | | | | |
Collapse
|
39
|
Wahaj SA, Place NJ, Weldele ML, Glickman SE, Holekamp KE. Siblicide in the spotted hyena: analysis with ultrasonic examination of wild and captive individuals. Behav Ecol 2007. [DOI: 10.1093/beheco/arm076] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
40
|
Conley AJ, Corbin CJ, Browne P, Mapes SM, Place NJ, Hughes AL, Glickman SE. Placental Expression and Molecular Characterization of Aromatase Cytochrome P450 in the Spotted Hyena (Crocuta crocuta). Placenta 2007; 28:668-75. [PMID: 17198727 DOI: 10.1016/j.placenta.2006.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 11/13/2006] [Accepted: 11/17/2006] [Indexed: 11/29/2022]
Abstract
At birth, the external genitalia of female spotted hyenas (Crocuta crocuta) are the most masculinized of any known mammal, but are still sexually differentiated. Placental aromatase cytochrome P450 (P450arom) is an important route of androgen metabolism protecting human female fetuses from virilization in utero. Therefore, placental P450arom expression was examined in spotted hyenas to determine levels during genital differentiation, and to compare molecular characteristics between the hyena and human placental enzymes. Hyena placental P450arom activity was determined at gestational days (GD) 31, 35, 45, 65 and 95 (term, 110), and the relative sensitivity of hyena and human placental enzyme to inhibition by the specific inhibitor, Letrozole, was also examined. Expression of hyena P450arom in placenta was localized by immuno-histochemistry, and a full-length cDNA was cloned for phylogenetic analysis. Aromatase activity increased from GD31 to a peak at 45 and 65, apparently decreasing later in gestation. This activity was more sensitive to inhibition by Letrozole than was human placental aromatase activity. Expression of P450arom was localized to syncytiotrophoblast and giant cells of mid-gestation placentas. The coding sequence of hyena P450arom was 94% and 86% identical to the canine and human enzymes respectively, as reflected by phylogenetic analyses. These data demonstrate for the first time that hyena placental aromatase activity is comparable to that of human placentas when genital differentiation is in progress. This suggests that even in female spotted hyenas clitoral differentiation is likely protected from virilization by placental androgen metabolism. Decreased placental aromatase activity in late gestation may be equally important in allowing androgen to program behaviors at birth. Although hyena P450arom is closely related to the canine enzyme, both placental anatomy and P450arom expression differ. Other hyaenids and carnivores must be investigated to determine the morphological and functional ancestral state of their placentas, as it relates to evolutionary relationships among species in this important taxonomic group.
Collapse
Affiliation(s)
- A J Conley
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, 1 Shields Avenue, Davis, CA 95616, USA.
| | | | | | | | | | | | | |
Collapse
|
41
|
Siblicide in Serengeti spotted hyenas: a long-term study of maternal input and cub survival. Behav Ecol Sociobiol 2007. [DOI: 10.1007/s00265-007-0421-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
42
|
White PP. Maternal response to neonatal sibling conflict in the spotted hyena, Crocuta crocuta. Behav Ecol Sociobiol 2007. [DOI: 10.1007/s00265-007-0422-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
43
|
Wagner AP, Frank LG, Creel S, Coscia EM. Transient genital abnormalities in striped hyenas (Hyaena hyaena). Horm Behav 2007; 51:626-32. [PMID: 17442316 DOI: 10.1016/j.yhbeh.2007.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2006] [Revised: 03/05/2007] [Accepted: 03/07/2007] [Indexed: 10/23/2022]
Abstract
The highly masculinized genitalia of female spotted hyenas Crocuta crocuta is unique among mammals: Crocuta have no external vagina so urination, penile intromission and parturition take place through the clitoris, which mimics a fully erectile male penis. Among hyenids, virilization of external female genitalia has previously been observed only in Crocuta, so functional explanations of masculinization have focused on aspects of social ecology unique to the species. Here we first show that the striped hyena Hyaena hyaena exhibits both unusual similarity in male and female androgen concentrations and transient genital anomalies characterized by a convergence in genital appearance among young males and females. We then evaluate hypotheses regarding the evolution of genital masculinization in the Hyaenidae and other taxa. Hyaena are behaviorally solitary, so discovery of unusual genital development patterns in this species does not support any current evolutionary models for masculinization in Crocuta, which all rely on the trait originating within a highly social species. Some hypotheses can be modified so that masculinization in Crocuta represents an extreme elaboration of a preexisting trait, shared as a homology with Hyaena.
Collapse
Affiliation(s)
- Aaron P Wagner
- Department of Ecology, Montana State University, Bozeman, MT 59717, USA.
| | | | | | | |
Collapse
|
44
|
Uller T. Sex-specific sibling interactions and offspring fitness in vertebrates: patterns and implications for maternal sex ratios. Biol Rev Camb Philos Soc 2006; 81:207-17. [PMID: 16677432 DOI: 10.1017/s1464793105006962] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 11/04/2005] [Accepted: 11/04/2005] [Indexed: 11/06/2022]
Abstract
Vertebrate sex ratios are notorious for their lack of fit to theoretical models, both with respect to the direction and the magnitude of the sex ratio adjustment. The reasons for this are likely to be linked to simplifying assumptions regarding vertebrate life histories. More specifically, if the sex ratio adjustment itself influences offspring fitness, due to sex-specific interactions among offspring, this could affect optimal sex ratios. A review of the literature suggests that sex-specific sibling interactions in vertebrates result from three major causes: (i) sex asymmetries in competitive ability, for example due to sexual dimorphism, (ii) sex-specific cooperation or helping, and (iii) sex asymmetries in non-competitive interactions, for example steroid leakage between fetuses. Incorporating sex-specific sibling interactions into a sex ratio model shows that they will affect maternal sex ratio strategies and, under some conditions, can repress other selection pressures for sex ratio adjustment. Furthermore, sex-specific interactions could also explain patterns of within-brood sex ratio (e.g. in relation to laying order). Failure to take sex-specific sibling interactions into account could partly explain the lack of sex ratio adjustment in accordance with theoretical expectations in vertebrates, and differences among taxa in sex-specific sibling interactions generate predictions for comparative and experimental studies.
Collapse
Affiliation(s)
- Tobias Uller
- School of Biological Sciences, University of Wollongong, NSW 2522, Australia.
| |
Collapse
|
45
|
Lark KG, Chase K, Sutter NB. Genetic architecture of the dog: sexual size dimorphism and functional morphology. Trends Genet 2006; 22:537-44. [PMID: 16934357 PMCID: PMC2785546 DOI: 10.1016/j.tig.2006.08.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 05/11/2006] [Accepted: 08/04/2006] [Indexed: 10/24/2022]
Abstract
Purebred dogs are a valuable resource for genetic analysis of quantitative traits. Quantitative traits are complex, controlled by many genes that are contained within regions of the genome known as quantitative trait loci (QTL). The genetic architecture of quantitative traits is defined by the characteristics of these genes: their number, the magnitude of their effects, their positions in the genome and their interactions with each other. QTL analysis is a valuable tool for exploring genetic architecture, and highlighting regions of the genome that contribute to the variation of a trait within a population.
Collapse
Affiliation(s)
- Karl G Lark
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA.
| | | | | |
Collapse
|
46
|
McFadden D, Pasanen EG, Weldele ML, Glickman SE, Place NJ. Masculinized otoacoustic emissions in female spotted hyenas (Crocuta crocuta). Horm Behav 2006; 50:285-92. [PMID: 16682033 DOI: 10.1016/j.yhbeh.2006.03.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Revised: 03/22/2006] [Accepted: 03/23/2006] [Indexed: 10/24/2022]
Abstract
In humans and rhesus monkeys, click-evoked otoacoustic emissions (CEOAEs) are stronger in females than in males, and there is considerable circumstantial evidence that this sex difference is attributable to the greater exposure to androgens prenatally in males. Because female spotted hyenas are highly androgenized beginning early in prenatal development, we expected an absence of sexual dimorphism in the CEOAEs of this species. The CEOAEs obtained from 9 male and 7 female spotted hyenas confirmed that expectation. The implication is that the marked androgenization to which female spotted hyenas are exposed masculinizes the cochlear mechanism responsible for CEOAEs. The CEOAEs measured in 3 male and 3 female hyenas that had been treated with anti-androgenic agents during prenatal development were stronger than the CEOAEs of the untreated animals, in accord with the implied inverse relationship between prenatal androgen exposure and the strength of the cochlear mechanisms producing CEOAEs. The CEOAEs of three ovariectomized females and two castrated males were essentially the same as those for the untreated females and males, suggesting that there is little or no activational effect of hormones on CEOAE strength in spotted hyenas. Distortion product OAEs (DPOAEs) also were measured. Those sex differences also were generally small (as they are in humans), and the effects of the anti-androgen agents were inconsistent. Thus, prenatal androgen exposure apparently does affect OAEs, but the effects appear to be greater for the reflection-based cochlear mechanism that underlies CEOAEs than for the nonlinear cochlear mechanism underlying DPOAEs.
Collapse
Affiliation(s)
- Dennis McFadden
- Department of Psychology and Center for Perceptual Systems, University of Texas, 1 University Station A8000, Austin, TX 78712-0187, USA.
| | | | | | | | | |
Collapse
|
47
|
|
48
|
Abstract
Drawing on the concepts and theory of dominance in adult vertebrates, this article categorizes the relationships of dominance between infant siblings, identifies the behavioral mechanisms that give rise to those relationships, and proposes a model to explain their evolution. Dominance relationships in avian broods can be classified according to the agonistic roles of dominants and subordinates as "aggression-submission," "aggression-resistance," "aggression-aggression," "aggression-avoidance," "rotating dominance," and "flock dominance." These relationships differ mainly in the submissiveness/pugnacity of subordinates, which is pivotal, and in the specificity/generality of the learning processes that underlie them. As in the dominance hierarchies of adult vertebrates, agonistic roles are engendered and maintained by several mechanisms, including differential fighting ability, assessment, trained winning and losing (especially in altricial species), learned individual relationships (especially in precocial species), site-specific learning, and probably group-level effects. An evolutionary framework in which the species-typical dominance relationship is determined by feeding mode, confinement, cost of subordination, and capacity for individual recognition, can be extended to mammalian litters and account for the aggression-submission and aggression-resistance observed in distinct populations of spotted hyenas and the "site-specific dominance" (teat ownership) of some pigs, felids, and hyraxes. Little is known about agonism in the litters of other mammals or broods of poikilotherms, but some species of fish and crocodilians have the potential for dominance among broodmates.
Collapse
Affiliation(s)
- Hugh Drummond
- Instituto de Ecología, Universidad Nacional Autónoma de México DF.
| |
Collapse
|
49
|
Leippert D, Goymann W, Hofer H. Between-litter siblicide in captive Indian false vampire bats (Megaderma lyra). J Zool (1987) 2006. [DOI: 10.1111/j.1469-7998.2000.tb00810.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
50
|
Archer J. Testosterone and human aggression: an evaluation of the challenge hypothesis. Neurosci Biobehav Rev 2006; 30:319-45. [PMID: 16483890 DOI: 10.1016/j.neubiorev.2004.12.007] [Citation(s) in RCA: 828] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 11/05/2004] [Accepted: 12/02/2004] [Indexed: 11/16/2022]
Abstract
Research on testosterone-behavior relationships in humans is assessed in relation to a version of the challenge hypothesis, originally proposed to account for testosterone-aggression associations in monogamous birds. Predictions were that that testosterone would rise at puberty to moderate levels, which supported reproductive physiology and behavior. Sexual arousal and challenges involving young males would raise testosterone levels further. In turn, this would facilitate direct competitive behavior, including aggression. When males are required to care for offspring, testosterone levels will decrease. Testosterone levels will also be associated with different behavioral profiles among men, associated with life history strategies involving emphasis on either mating or parental effort. Most of these predictions were supported by the review of current research, although most studies were not designed to specifically test the challenge hypothesis.
Collapse
Affiliation(s)
- John Archer
- Department of Psychology, University of Central Lancashire, Preston, Lancashire PR12HE, UK.
| |
Collapse
|