1
|
Maag N, Cozzi G, Seager D, Manser M, Sickmüller A, Hildebrandt TB, Clutton-Brock T, Ozgul A. Dispersal-induced social stress prolongs gestation in wild meerkats. Biol Lett 2023; 19:20230183. [PMID: 37376852 PMCID: PMC10300508 DOI: 10.1098/rsbl.2023.0183] [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: 04/21/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
In the majority of mammals, gestation length is relatively consistent and seldom varies by more than 3%. In a few species, females can adjust gestation length by delaying the development of the embryo after implantation. Delays in embryonic development allow females to defer the rising energetic costs of gestation when conditions are unfavourable, reducing the risk of embryo loss. Dispersal in mammals that breed cooperatively is a period when food intake is likely to be suppressed and stress levels are likely to be high. Here, we show that pregnant dispersing meerkats (Suricata suricatta), which have been aggressively evicted from their natal group and experience weight loss and extended periods of social stress, prolong their gestation by means of delayed embryonic development. Repeated ultrasound scans of wild, unanaesthetized females throughout their pregnancies showed that pregnancies of dispersers were on average 6.3% longer and more variable in length (52-65 days) than those of residents (54-56 days). The variation in dispersers shows that, unlike most mammals, meerkats can adapt to stress by adjusting their pregnancy length by up to 25%. By doing so, they potentially rearrange the costs of gestation during adverse conditions of dispersal and enhance offspring survival.
Collapse
Affiliation(s)
- Nino Maag
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
| | - Gabriele Cozzi
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
| | - David Seager
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Marta Manser
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
- Mammal Research Institute, University of Pretoria, cnr Lynnwood Road and Roper Street, Hatfield 0028, South Africa
| | - Anna Sickmüller
- Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315 Berlin, Germany
| | - Thomas B. Hildebrandt
- Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315 Berlin, Germany
- Freie Universität Berlin, Kaiserwerther Strasse 16-18, 14195 Berlin, Germany
| | - Tim Clutton-Brock
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Mammal Research Institute, University of Pretoria, cnr Lynnwood Road and Roper Street, Hatfield 0028, South Africa
| | - Arpat Ozgul
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland
- Kalahari Research Centre, Kuruman River Reserve, Van Zylsrus 8467, South Africa
| |
Collapse
|
2
|
Drea CM, Davies CS. Meerkat manners: Endocrine mediation of female dominance and reproductive control in a cooperative breeder. Horm Behav 2022; 145:105245. [PMID: 35988450 DOI: 10.1016/j.yhbeh.2022.105245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/18/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022]
Abstract
This article is part of a Special Issue (Hormones and Hierarchies). To gain more balanced understanding of sexual selection and mammalian sexual differentiation processes, this review addresses behavioral sex differences and hormonal mediators of intrasexual competition in the meerkat (Suricata suricatta) - a cooperative breeder unusual among vertebrates in its female aggression, degree of reproductive skew, and phenotypic divergence. Focused on the evolution, function, mechanism, and development of female dominance, the male remains a key reference point throughout. Integrated review of endocrine function does not support routine physiological suppression in subordinates of either sex, but instead a ramp up of weight, reproduction, aggression, and sex steroids, particularly androgens, in dominant females. Important and timely questions about female competition are thus addressed by shifting emphasis from mediators of reproductive suppression to mediators of reproductive control, and from organizational and activational roles of androgens in males to their roles in females. Unusually, we ask not only how inequity is maintained, but how dominance is acquired within a lifetime and across generations. Antiandrogens administered in the field to males and pregnant dominant females confirm the importance of androgen-mediated food competition. Moreover, effects of maternal endocrine milieu on offspring development reveal a heritable, androgenic route to female aggression, likely promoting reproductive priority along dominant matrilines. Integrating endocrine measures with long-term behavioral, ecological, morphological, and life-history data on normative and experimental individuals, across life stages and generations, provides better appreciation of the role of naturally circulating androgens in regulating the female phenotype, and sheds new light on the evolution of female dominance, reproductive inequity, and cooperative breeding.
Collapse
Affiliation(s)
- Christine M Drea
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708-0383, USA; Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa.
| | - Charli S Davies
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708-0383, USA; Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
| |
Collapse
|
3
|
Drea CM, Davies CS, Greene LK, Mitchell J, Blondel DV, Shearer CL, Feldblum JT, Dimac-Stohl KA, Smyth-Kabay KN, Clutton-Brock TH. An intergenerational androgenic mechanism of female intrasexual competition in the cooperatively breeding meerkat. Nat Commun 2021; 12:7332. [PMID: 34921140 PMCID: PMC8683399 DOI: 10.1038/s41467-021-27496-x] [Citation(s) in RCA: 3] [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: 12/28/2020] [Accepted: 11/22/2021] [Indexed: 12/27/2022] Open
Abstract
Female intrasexual competition can be intense in cooperatively breeding species, with some dominant breeders (matriarchs) limiting reproduction in subordinates via aggression, eviction or infanticide. In males, such tendencies bidirectionally link to testosterone, but in females, there has been little systematic investigation of androgen-mediated behaviour within and across generations. In 22 clans of wild meerkats (Suricata suricatta), we show that matriarchs 1) express peak androgen concentrations during late gestation, 2) when displaying peak feeding competition, dominance behaviour, and evictions, and 3) relative to subordinates, produce offspring that are more aggressive in early development. Late-gestation antiandrogen treatment of matriarchs 4) specifically reduces dominance behaviour, is associated with infrequent evictions, decreases social centrality within the clan, 5) increases aggression in cohabiting subordinate dams, and 6) reduces offspring aggression. These effects implicate androgen-mediated aggression in the operation of female sexual selection, and intergenerational transmission of masculinised phenotypes in the evolution of meerkat cooperative breeding.
Collapse
Affiliation(s)
- Christine M Drea
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA.
- Department of Biology, Duke University, Durham, NC, 27708, USA.
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa.
| | - Charli S Davies
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Lydia K Greene
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Duke Lemur Center, Duke University, Durham, NC, 27705, USA
| | - Jessica Mitchell
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Nuffield Centre for International Health and Development, University of Leeds, Leeds, West Yorkshire, LS2 9JT, UK
| | - Dimitri V Blondel
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Department of Biology, North Carolina Wesleyan College, Rocky Mount, NC, 27804, USA
| | - Caroline L Shearer
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
| | - Joseph T Feldblum
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Department of Anthropology and Society of Fellows, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kristin A Dimac-Stohl
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Department of Biology, Duke University, Durham, NC, 27708, USA
| | - Kendra N Smyth-Kabay
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Boston Consulting Group, Bethesda, MD, 20814, USA
| | - Tim H Clutton-Brock
- Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
- Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK
- Mammal Research Institute, University of Pretoria, 0002, Pretoria, South Africa
| |
Collapse
|
4
|
Feleke BE, Feleke TE, Nigussie AA, Misgan E. The effects of stillbirth and abortion on the next pregnancy: a longitudinal study. BMC WOMENS HEALTH 2021; 21:340. [PMID: 34563190 PMCID: PMC8464111 DOI: 10.1186/s12905-021-01485-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 09/02/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND Abortion and stillbirths are the common obstetrics condition in Ethiopia and their effect on the next pregnancy was not well identified in resource limited settings. The aim of the study was to assess the effect of stillbirth and abortion on the next pregnancy. METHODS A prospective cohort study design was implemented. The study was conducted in Mecha demographic surveillance and field research center catchment areas. The data were collected from January 2015 to March 2019. Epi-info software was used to calculate the sample size. The systematic random sampling technique was used to select stillbirth and abortion women. Poison regression was used to identify the predictors of MCH service utilization; descriptive statistics were used to identify the prevalence of blood borne pathogens. The Kaplan Meier survival curve was used to estimate survival to pregnancy and pregnancy related medical disorders. RESULTS 1091 stillbirth and 3,026 abortion women were followed. Hepatitis B was present in 6% of abortion and 3.2% of stillbirth women. Hepatitis C was diagnosed in 4.7% of abortion and 0.3% of stillbirth women. HIV was detected in 3% of abortion and 0.8% of stillbirth women. MCH service utilization was determined by knowledge of contraceptives [IRR 1.29, 95% CI 1.18-1.42], tertiary education [IRR 4.29, 95% CI 3.72-4.96], secondary education. [IRR 3.14, 95% CI 2.73-3.61], married women [IRR 2.08, 95% CI 1.84-2.34], family size [IRR 0.67, 95% CI 1.001-1.01], the median time of pregnancy after stillbirth and abortion were 12 months. Ante-partum hemorrhage was observed in 23.1% of pregnant mothers with a past history of abortion cases and post-partum hemorrhage was observed in 25.6% of pregnant mothers with a past history of abortion. PREGNANCY INDUCED DIABETES MELLITUS was observed 14.3% of pregnant mothers with a past history of stillbirth and pregnancy-induced hypertension were observed in 9.2% of mothers with a past history of stillbirth. CONCLUSION Obstetric hemorrhage was the common complications of abortion women while Pregnancy-induced diabetic Mellitus and pregnancy-induced hypertension were the most common complications of stillbirth for the next pregnancy.
Collapse
Affiliation(s)
- Berhanu Elfu Feleke
- Department of Epidemiology and Biostatistics, University of Bahir Dar, Bahir Dar, Ethiopia.
| | | | | | - Eyaya Misgan
- Department of Gynecology and Obstetrics, University of Bahir Dar, Bahir Dar, Ethiopia
| |
Collapse
|
5
|
Freeman AR. Female-female reproductive suppression: impacts on signals and behavior. Integr Comp Biol 2021; 61:1827-1840. [PMID: 33871603 DOI: 10.1093/icb/icab027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Female-female reproductive suppression is evident in an array of mammals, including rodents, primates, and carnivores. By suppressing others, breeding females can benefit by reducing competition from other females and their offspring. There are neuroendocrinological changes during suppression which result in altered behavior, reproductive cycling, and communication. This review, which focuses on species in Rodentia, explores the current theoretical frameworks of female-female reproductive suppression, how female presence and rank impacts reproductive suppression, and some of the proposed mechanisms of suppression. Finally, the understudied role of olfactory communication in female-female reproductive suppression is discussed to identify current gaps in our understanding of this topic.
Collapse
Affiliation(s)
- Angela R Freeman
- Department of Psychology, Cornell University, 211 Uris Hall, Cornell University, Ithaca, NY 14853
| |
Collapse
|
6
|
Liu N, Chen J, He Y, Jia H, Jiang D, Li S, Yang Y, Dai Z, Wu Z, Wu G. Effects of maternal L-proline supplementation on inflammatory cytokines at the placenta and fetus interface of mice. Amino Acids 2020; 52:587-596. [PMID: 32170468 DOI: 10.1007/s00726-020-02837-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 03/06/2020] [Indexed: 12/12/2022]
Abstract
Dietary L-proline (proline) supplementation during gestation enhances fetal survival and placental development in mice. The objective of the present study was to test the hypothesis that this beneficial effect of proline was associated with alterations in inflammatory response at the placenta and fetus interface. Populations of immune cells present in peripheral blood mononuclear cells (PBMC) were determined by flow cytometry analysis. The concentrations of immunoglobulins in plasma, and the concentrations of cytokines in plasma, uterus, placenta, and amniotic fluid were measured using a bead-based immunoassay. The data showed that proline supplementation led to higher (P < 0.05) populations of B lymphocytes (CD3-CD19+), natural killer (NK) cells (CD3-NK1.1+), and dendritic cells (DCs, CD11c+MHCII+) in peripheral blood, as compared with the controls. Conversely, mice fed a proline-supplemented diet had a lower population of neutrophils (CD11b+F4/80-). Further study showed that proline supplementation decreased (P < 0.05) the concentrations of (1) interleukin (IL)-23, IL-1α, and IL-6 in plasma; (2) IL-6 in the uterus; and (3) tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein (MCP)-1, and IL-17 in the placenta; and (4) interferon (IFN)-γ in amniotic fluid, compared with controls. Conversely, proline supplementation resulted in higher (P < 0.05) concentrations of (1) IL-10, IL-17 and granulocyte-macrophage colony-stimulating factor (GM-CSF) in plasma; (2) IL-10 and IL-1α in the uterus; and (3) IL-1α, IL-1β, IL-10, IL-27, and IFN-β in amniotic fluid, compared with controls. Moreover, concentrations of immunoglobulin (Ig) G2b and IgM were enhanced (P < 0.05) by proline administration. Taken together, our results reveal a regulatory effect of proline in the immunological response at the maternal-fetal interface, which is critical for embryonic development and fetal survival.
Collapse
Affiliation(s)
- Ning Liu
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Jingqing Chen
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Yu He
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Hai Jia
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Da Jiang
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Shuai Li
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Ying Yang
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Zhaolai Dai
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China
| | - Zhenlong Wu
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
| | - Guoyao Wu
- Department of Animal Nutrition and Feed Science, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
- Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
| |
Collapse
|
7
|
Solano ME, Arck PC. Steroids, Pregnancy and Fetal Development. Front Immunol 2020; 10:3017. [PMID: 32038609 PMCID: PMC6987319 DOI: 10.3389/fimmu.2019.03017] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 12/09/2019] [Indexed: 12/21/2022] Open
Abstract
Maternal glucocorticoids critically rise during pregnancy reaching up to a 20-fold increase of mid-pregnancy concentrations. Concurrently, another steroid hormone, progesterone, increases. Progesterone, which shows structural similarities to glucocorticoids, can bind the intracellular glucocorticoid receptor, although with lower affinity. Progesterone is essential for the establishment and continuation of pregnancy and it is generally acknowledged to promote maternal immune tolerance to fetal alloantigens through a wealth of immunomodulatory mechanisms. Despite the potent immunomodulatory capacity of glucocorticoids, little is known about their role during pregnancy. Here we aim to compare general aspects of glucocorticoids and progesterone during pregnancy, including shared common steroidogenic pathways, plasma transporters, regulatory pathways, expression of receptors, and mechanisms of action in immune cells. It was recently acknowledged that progesterone receptors are not ubiquitously expressed on immune cells and that pivotal features of progesterone induced- maternal immune adaptations to pregnancy are mediated via the glucocorticoid receptor, including e.g., T regulatory cells expansion. We hypothesize that a tight equilibrium between progesterone and glucocorticoids is critically required and recapitulate evidence supporting that their disequilibrium underlie pregnancy complications. Such a disequilibrium can occur, e.g., after maternal stress perception, which triggers the release of glucocorticoids and impair progesterone secretion, resulting in intrauterine inflammation. These endocrine misbalance might be interconnected, as increase in glucocorticoid synthesis, e.g., upon stress, may occur in detriment of progesterone steroidogenesis, by depleting the common precursor pregnenolone. Abundant literature supports that progesterone deficiency underlies pregnancy complications in which immune tolerance is challenged. In these settings, it is largely yet undefined if and how glucocorticoids are affected. However, although progesterone immunomodulation during pregnancy appear to be chiefly mediated glucocorticoid receptors, excess glucocorticoids cannot compensate by progesterone deficiency, indicating that additional und still undercover mechanisms are at play.
Collapse
Affiliation(s)
- Maria Emilia Solano
- Department for Obstetrics and Fetal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Petra Clara Arck
- Department for Obstetrics and Fetal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| |
Collapse
|
8
|
Rosenbaum S, Gettler LT. With a little help from her friends (and family) part II: Non-maternal caregiving behavior and physiology in mammals. Physiol Behav 2019; 193:12-24. [PMID: 29933837 DOI: 10.1016/j.physbeh.2017.12.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 12/21/2017] [Indexed: 12/15/2022]
Abstract
The diversity of competing frameworks for explaining the evolution of non-maternal care in mammals (Part I, this issue) reflects the vast range of behaviors and associated outcomes these theories attempt to subsume. Caretaking comprises a wide variety of behavioral domains, and is mediated by an equally large range of physiological systems. In Part II, we provide an overview of how non-maternal care in mammals is expressed, the ways in which it is regulated, and the many effects such care has on both recipients and caretakers. We also discuss the two primary ways in which closer integration of ultimate and proximate levels of explanation can be useful when addressing questions about non-maternal caretaking. Specifically, proximate mechanisms provide important functional clues, and are key to testing theory concerning evolutionary tradeoffs. Finally, we highlight a number of methodological and publication biases that currently shape the literature, which provide opportunities for knowledge advancement in this domain going forward. In this conclusion to our two-part introduction, we provide a broad survey of the behavior and physiology that the contributions to this special issue represent.
Collapse
Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, Northwestern University, Evanston, IL, United States; Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, IL, United States.
| | - Lee T Gettler
- Department of Anthropology, University of Notre Dame, Notre Dame, IN, United States; The Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| |
Collapse
|
9
|
Rosenbaum S, Gettler LT. With a little help from her friends (and family) part I: the ecology and evolution of non-maternal care in mammals. Physiol Behav 2019; 193:1-11. [PMID: 29933836 DOI: 10.1016/j.physbeh.2017.12.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 11/27/2017] [Accepted: 12/20/2017] [Indexed: 10/28/2022]
Abstract
In the class Mammalia, most young are cared for exclusively by their mothers. In species where mothers receive help, however, non-maternal caregivers may play a crucial role in development and life history trajectories. In turn, recipients of such care may have important impacts on caregivers of all types. In Part I of this overview, we briefly review the evolutionary barriers to widespread non-maternal care in mammals, and explain why the exceptions are of particular theoretical importance. We also summarize the current understanding of the selective forces leading to non-maternal care, and the taxa and types of caretakers amongst which it occurs. Finally, we argue for a fresh look at the categorization schemes that have traditionally been used to separate various types of mammalian non-maternal caregivers. This two-part introduction is aimed at scientists from multiple disciplines who study diverse organismal systems. It draws from the social and biological sciences literatures to provide an overview of this special issue of Physiology and Behavior's suite of methodological offerings and theoretical underpinnings.
Collapse
Affiliation(s)
- Stacy Rosenbaum
- Department of Anthropology, Northwestern University, Evanston, IL, United States; Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, IL, United States.
| | - Lee T Gettler
- Department of Anthropology, University of Notre Dame, Notre Dame, IN, United States; The Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| |
Collapse
|
10
|
Smyth KN, Caruso NM, Davies CS, Clutton-Brock TH, Drea CM. Social and endocrine correlates of immune function in meerkats: implications for the immunocompetence handicap hypothesis. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180435. [PMID: 30225031 PMCID: PMC6124081 DOI: 10.1098/rsos.180435] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
Social status can mediate effects on the immune system, with profound consequences for individual health; nevertheless, most investigators of status-related disparities in free-ranging animals have used faecal parasite burdens to proxy immune function in the males of male-dominant species. We instead use direct measures of innate immune function (complement and natural antibodies) to examine status-related immunocompetence in both sexes of a female-dominant species. The meerkat is a unique model for such a study because it is a cooperatively breeding species in which status-related differences are extreme, evident in reproductive skew, morphology, behaviour, communication and physiology, including that dominant females naturally express the greatest total androgen (androstenedione plus testosterone) concentrations. We found that, relative to subordinates, dominant animals had reduced serum bacteria-killing abilities; also, relative to subordinate females, dominant females had reduced haemolytic complement activities. Irrespective of an individual's sex or social status, androstenedione concentrations (but not body condition, age or reproductive activity) negatively predicted concurrent immunocompetence. Thus, dominant meerkats of both sexes are immunocompromised. Moreover, in female meerkats, androstenedione perhaps acting directly or via local conversion, may exert a double-edged effect of promoting dominance and reproductive success at the cost of increased parasitism and reduced immune function. Given the prominent signalling of dominance in female meerkats, these findings may relate to the immunocompetence handicap hypothesis (ICHH); however, our data would suggest that the endocrine mechanism underlying the ICHH need not be mediated solely by testosterone and might explain trade-offs in females, as well as in males.
Collapse
Affiliation(s)
- Kendra N. Smyth
- University Program in Ecology, Duke University, Durham, NC, USA
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
- Kalahari Research Trust, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
| | - Nicholas M. Caruso
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Charli S. Davies
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
- Kalahari Research Trust, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
| | - Tim H. Clutton-Brock
- Kalahari Research Trust, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
- Department of Zoology, University of Cambridge, Cambridge, UK
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Christine M. Drea
- University Program in Ecology, Duke University, Durham, NC, USA
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA
- Department of Biology, Duke University, Durham, NC, USA
- Kalahari Research Trust, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa
| |
Collapse
|