1
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Soler JJ, Møller AP. Defensive tolerance to parasitism is correlated with sexual selection in swallows. Oecologia 2023; 203:267-276. [PMID: 37462738 PMCID: PMC10684419 DOI: 10.1007/s00442-023-05419-5] [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: 12/19/2022] [Accepted: 07/07/2023] [Indexed: 11/18/2023]
Abstract
Parasite-mediated sexual selection has been the topic of extensive research and enthusiastic debate for more than three decades. Here, we suggest that secondary sexual characters may not only signal parasite resistance but also defensive tolerance. We exemplify this possibility by analysing information on two sexually selected traits, annual reproductive success, and ectoparasitism in a barn swallow Hirundo rustica population followed for more than 30 years. For each individual, we estimated the slope of the association between reproductive success and parasitism as an index of tolerance and subsequently explored the association with the expression of the sexually selected traits. In accordance with expectations of parasites playing a role in sexual selection, tail length was negatively related to load of chewing lice and nest size was positively related to tolerance to chewing lice. We discuss the importance of considering defensive tolerance for understanding the role of parasite-mediated sexual selection.
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Affiliation(s)
- Juan José Soler
- Depto. Ecología Funcional Y Evolutiva, Estación Experimental de Zonas Áridas, Sacramento S/N, La Cañada de San Urbano, 04120, Almería, Spain.
| | - Anders Pape Møller
- Ecologie Systématique Evolution, Université Paris-Sud, CNRS, Orsay, France
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2
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Dougherty LR, Rovenolt F, Luyet A, Jokela J, Stephenson JF. Ornaments indicate parasite load only if they are dynamic or parasites are contagious. Evol Lett 2023; 7:176-190. [PMID: 37251584 PMCID: PMC10210455 DOI: 10.1093/evlett/qrad017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 04/11/2023] [Accepted: 04/18/2023] [Indexed: 05/31/2023] Open
Abstract
Choosing to mate with an infected partner has several potential fitness costs, including disease transmission and infection-induced reductions in fecundity and parental care. By instead choosing a mate with no, or few, parasites, animals avoid these costs and may also obtain resistance genes for offspring. Within a population, then, the quality of sexually selected ornaments on which mate choice is based should correlate negatively with the number of parasites with which a host is infected ("parasite load"). However, the hundreds of tests of this prediction yield positive, negative, or no correlation between parasite load and ornament quality. Here, we use phylogenetically controlled meta-analysis of 424 correlations from 142 studies on a wide range of host and parasite taxa to evaluate explanations for this ambiguity. We found that ornament quality is weakly negatively correlated with parasite load overall, but the relationship is more strongly negative among ornaments that can dynamically change in quality, such as behavioral displays and skin pigmentation, and thus can accurately reflect current parasite load. The relationship was also more strongly negative among parasites that can transmit during sex. Thus, the direct benefit of avoiding parasite transmission may be a key driver of parasite-mediated sexual selection. No other moderators, including methodological details and whether males exhibit parental care, explained the substantial heterogeneity in our data set. We hope to stimulate research that more inclusively considers the many and varied ways in which parasites, sexual selection, and epidemiology intersect.
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Affiliation(s)
- Liam R Dougherty
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, United Kingdom
| | - Faith Rovenolt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Alexia Luyet
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Institute for Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Jukka Jokela
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Institute for Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Jessica F Stephenson
- Corresponding author: University of Pittsburgh Department of Biological Sciences, Clapp Hall, 4249 Fifth Avenue, Pittsburgh, PA 15260 USA.
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3
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Gómez-Llano M, McPeek MA, Siepielski AM. Environmental variation shapes and links parasitism to sexual selection. Evol Ecol 2023. [DOI: 10.1007/s10682-023-10236-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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4
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Cronin AD, Smit JAH, Muñoz MI, Poirier A, Moran PA, Jerem P, Halfwerk W. A comprehensive overview of the effects of urbanisation on sexual selection and sexual traits. Biol Rev Camb Philos Soc 2022; 97:1325-1345. [PMID: 35262266 PMCID: PMC9541148 DOI: 10.1111/brv.12845] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 12/18/2022]
Abstract
Urbanisation can affect mating opportunities and thereby alter inter- and intra-sexual selection pressures on sexual traits. Biotic and abiotic urban conditions can influence an individual's success in pre- and post-copulatory mating, for example through impacts on mate attraction and mate preference, fertilisation success, resource competition or rival interactions. Divergent sexual selection pressures can lead to differences in behavioural, physiological, morphological or life-history traits between urban and non-urban populations, ultimately driving adaptation and speciation. Most studies on urban sexual selection and mating interactions report differences between urban and non-urban populations or correlations between sexual traits and factors associated with increased urbanisation, such as pollution, food availability and risk of predation and parasitism. Here we review the literature on sexual selection and sexual traits in relation to urbanisation or urban-associated conditions. We provide an extensive list of abiotic and biotic factors that can influence processes involved in mating interactions, such as signal production and transmission, mate choice and mating opportunities. We discuss all relevant data through the lens of two, non-mutually exclusive theories on sexual selection, namely indicator and sensory models. Where possible, we indicate whether these models provide the same or different predictions regarding urban-adapted sexual signals and describe different experimental designs that can be useful for the different models as well as to investigate the drivers of sexual selection. We argue that we lack a good understanding of: (i) the factors driving urban sexual selection; (ii) whether reported changes in traits result in adaptive benefits; and (iii) whether these changes reflect a short-term ecological, or long-term evolutionary response. We highlight that urbanisation provides a unique opportunity to study the process and outcomes of sexual selection, but that this requires a highly integrative approach combining experimental and observational work.
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Affiliation(s)
- Andrew D Cronin
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Judith A H Smit
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Matías I Muñoz
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Armand Poirier
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Peter A Moran
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Paul Jerem
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
| | - Wouter Halfwerk
- Department of Ecological Sciences, Vrije Universiteit, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands
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5
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Gómez-Llano M, Narasimhan A, Svensson EI. Male-Male Competition Causes Parasite-Mediated Sexual Selection for Local Adaptation. Am Nat 2020; 196:344-354. [DOI: 10.1086/710039] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Carranza J, Pérez-Barbería J, Mateos C, Alarcos S, Torres-Porras J, Pérez-González J, Sánchez-Prieto CB, Valencia J, Castillo L, de la Peña E, Barja I, Seoane JM, Reglero MM, Flores A, Membrillo A. Social environment modulates investment in sex trait versus lifespan: red deer produce bigger antlers when facing more rivalry. Sci Rep 2020; 10:9234. [PMID: 32514059 PMCID: PMC7280183 DOI: 10.1038/s41598-020-65578-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 05/04/2020] [Indexed: 11/23/2022] Open
Abstract
Theory predicts that the plastic expression of sex-traits should be modulated not only by their production costs but also by the benefits derived from the presence of rivals and mates, yet there is a paucity of evidence for an adaptive response of sex-trait expression to social environment. We studied antler size, a costly and plastic sex trait, and tooth wear, a trait related to food intake and longevity, in over 4,000 male Iberian red deer (Cervus elaphus hispanicus) from 56 wild populations characterized by two contrasting management practices that affect male age structure and adult sex-ratio. As a consequence, these populations exhibit high and low levels of male-male competition for mating opportunities. We hypothesized that males under conditions of low intra-sexual competition would develop smaller antlers, after controlling for body size and age, than males under conditions of high intra-sexual competition, thus reducing energy demands (i.e. reducing intake and food comminution), and as a consequence, leading to less tooth wear and a concomitant longer potential lifespan. Our results supported these predictions. To reject possible uncontrolled factors that may have occurred in the wild populations, we carried out an experimental design on red deer in captivity, placing males in separate plots with females or with rival males during the period of antler growth. Males living with rivals grew larger antlers than males living in a female environment, which corroborates the results found in the wild populations. As far as we know, these results show, for the first time, the modulation of a sexual trait and its costs on longevity conditional upon the level of intra-sexual competition.
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Affiliation(s)
- Juan Carranza
- Wildlife Research Unit (UIRCP), Universidad de Córdoba, 14071, Córdoba, Spain.
| | - Javier Pérez-Barbería
- Wildlife Research Unit (UIRCP), Universidad de Córdoba, 14071, Córdoba, Spain
- Game and Livestock Resources Unit, University of Castilla-La Mancha, IDR, IREC, Albacete, 02071, Spain
| | - Concha Mateos
- Biology and Ethology Unit, Universidad de Extremadura, 10071, Cáceres, Spain
| | - Susana Alarcos
- Biology and Ethology Unit, Universidad de Extremadura, 10071, Cáceres, Spain
| | - Jerónimo Torres-Porras
- Department of Social and Experimental Sciences Teaching, Faculty of Educational Sciences, Universidad de Córdoba, 14071, Córdoba, Spain
| | | | | | - Juliana Valencia
- Didáctica de las Ciencias Experimentales, Facultad de Ciencias de la Educación, Universidad de Málaga, Málaga, Spain
| | - Leticia Castillo
- Biology and Ethology Unit, Universidad de Extremadura, 10071, Cáceres, Spain
| | - Eva de la Peña
- Wildlife Research Unit (UIRCP), Universidad de Córdoba, 14071, Córdoba, Spain
| | - Isabel Barja
- Department of Biology, Zoology Unit, Universidad Autónoma (UAM), 28049, Madrid, Spain
- Biodiversity and Global Change Research Centre (CIBC-UAM), Universidad Autónoma (UAM), 28049, Madrid, Spain
| | - José M Seoane
- Wildlife Research Unit (UIRCP), Universidad de Córdoba, 14071, Córdoba, Spain
| | - Manuel M Reglero
- Gestión Cinegética Integral S.L. and Lagunes Selección Genética S.L., Madrid, Spain
| | - Antonio Flores
- Biology and Ethology Unit, Universidad de Extremadura, 10071, Cáceres, Spain
| | - Alberto Membrillo
- Wildlife Research Unit (UIRCP), Universidad de Córdoba, 14071, Córdoba, Spain
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7
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Gould GM, Carter GG, Augustine JK. Divergent color signals from homologous unfeathered ornaments in two congeneric grouse. Ecol Evol 2019; 9:11833-11847. [PMID: 31695891 PMCID: PMC6822034 DOI: 10.1002/ece3.5687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 08/30/2019] [Accepted: 09/05/2019] [Indexed: 11/16/2022] Open
Abstract
Color-based visual signals are important aspects of communication throughout the animal kingdom. Individuals evaluate color to obtain information about age and condition and to behave accordingly. Birds display a variety of striking, conspicuous colors and make ideal subjects for the study of color signaling. While most studies of avian color focus on plumage, bare unfeathered body parts also display a wide range of color signals. Mate choice and intrasexual competitive interactions are easily observed in lekking grouse, which also signal with prominent unfeathered color patches. Most male grouse have one pair of colorful bare part ornaments (combs), and males of several species also have inflatable air sacs in their throat. Previous studies have mostly focused on comb color and size, but little is known about the signaling role of air sac color. We measured comb size and the color properties of combs and air sacs in the Lesser and Greater Prairie-Chickens (Tympanuchus pallidicinctus and T. cupido, respectively), and investigated whether these properties varied with age and mass. We found that mass predicted color properties of air sacs and that age predicted comb size in the Greater Prairie-Chicken, suggesting that these ornaments indicate condition dependence. No conclusive relationships between color and age or size were detected in the Lesser Prairie-Chicken. Color properties of both ornaments differed between the two species. Further research is needed to determine mechanisms that link condition to color and whether the information advertised by color signals from these ornaments is intended for males, females, or both.
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Affiliation(s)
- Geoffrey M. Gould
- Department of Evolution, Ecology and Organismal BiologyThe Ohio State UniversityColumbusOHUSA
| | - Gerald G. Carter
- Department of Evolution, Ecology and Organismal BiologyThe Ohio State UniversityColumbusOHUSA
| | - Jacqueline K. Augustine
- Department of Evolution, Ecology and Organismal BiologyThe Ohio State University at LimaLimaOHUSA
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8
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Scordato ESC. Male competition drives song divergence along an ecological gradient in an avian ring species. Evolution 2018; 72:2360-2377. [DOI: 10.1111/evo.13604] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 08/07/2018] [Accepted: 08/21/2018] [Indexed: 01/04/2023]
Affiliation(s)
- Elizabeth S. C. Scordato
- Committee on Evolutionary Biology The University of Chicago Chicago Illinois 60637
- Current Address: Department of Biological Sciences California State Polytechnic University Pomona California 91768
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9
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Jones P, Strickland B, Demarais S, Wang G, Dacus C. Nutrition and ontogeny influence weapon development in a long-lived mammal. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Selection in male cervids should optimize allocation of nutritional resources to the competing demands of body growth versus weapon development. We investigated allocation decisions of growing and mature male white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)) from three regions of low, moderate, and high diet quality. We tested (i) if deer under greater nutritional limitations would allocate proportionally less to antler growth, (ii) if antler and body mass became less variable with age, and (iii) if antler size consistently exhibited positive allometry with body mass across age classes and nutritional planes. Greater nutrition increased antler allocation in 2.5 to 4.5 year olds but not in yearlings or prime-aged males. Variability of antler mass decreased with age and was generally less in more fertile regions, but body mass was equally variable across all ages and regions. Antler mass was positively allometric with body mass for all combinations of age class and region but exhibited age- and region-related differences. Our results suggest that accruing body mass is more important to lifetime reproductive success than increasing weapon size. Reduced allometric coefficients in older males likely stem from increasing use of skeletal mineral reserves, selective pressures favoring greater body mass, and possible selection for optimal weapon strength and structure.
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Affiliation(s)
- P.D. Jones
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - B.K. Strickland
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - S. Demarais
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - G. Wang
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - C.M. Dacus
- Mississippi Department of Wildlife, Fisheries, and Parks, 1505 Eastover Drive, Jackson, MS 39211, USA
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10
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Richard FJ. Symbiotic Bacteria Influence the Odor and Mating Preference of Their Hosts. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00143] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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11
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Servedio MR, Boughman JW. The Role of Sexual Selection in Local Adaptation and Speciation. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2017. [DOI: 10.1146/annurev-ecolsys-110316-022905] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sexual selection plays several intricate and complex roles in the related processes of local adaptation and speciation. In some cases sexual selection can promote these processes, but in others it can be inhibitory. We present theoretical and empirical evidence supporting these dual effects of sexual selection during local adaptation, allopatric speciation, and speciation with gene flow. Much of the empirical evidence for sexual selection promoting speciation is suggestive rather than conclusive; we present what would constitute strong evidence for sexual selection driving speciation. We conclude that although there is ample evidence that sexual selection contributes to the speciation process, it is very likely to do so only in concert with natural selection.
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Affiliation(s)
- Maria R. Servedio
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Janette W. Boughman
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824
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McIntosh TL, Lee AJ, Sidari MJ, Stower RE, Sherlock JM, Dixson BJW. Microbes and masculinity: Does exposure to pathogenic cues alter women's preferences for male facial masculinity and beardedness? PLoS One 2017; 12:e0178206. [PMID: 28594843 PMCID: PMC5464545 DOI: 10.1371/journal.pone.0178206] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 05/08/2017] [Indexed: 11/18/2022] Open
Abstract
Women's preferences for men's androgen dependent secondary sexual traits are proposed to be phenotypically plastic in response to exposure to pathogens and pathogen disgust. While previous studies report that masculinity in facial shape is more attractive to women who have recently been exposed to pathogenic cues and who are high in self-reported pathogen disgust, facial hair may reduce male attractiveness under conditions of high pathogens as beards are a possible breeding ground for disease carrying ectoparasites. In the present study, we test whether women's preferences for beardedness and facial masculinity vary due to exposure to different pathogenic cues. Participants (N = 688, mean age + 1SD = 31.94 years, SD = 6.69, range = 18-67) rated the attractiveness of facial composite stimuli of men when they were clean-shaven or fully bearded. These stimuli were also manipulated in order to vary sexual dimorphism by ±50%. Ratings were conducted before and after exposure to one of four experimental treatments in which participants were primed to either high pathogens (e.g. infected cuts), ectoparasites (e.g. body lice), a mixture of pathogens and ectoparasites, or a control condition (e.g. innocuous liquids). Participants then completed the three-domain disgust scale measuring attitudes to moral, sexual and pathogen disgust. We predicted that women would prefer facial masculinity following exposure to pathogenic cues, but would show reduced preferences for facial hair following exposure to ectoparasites. Women preferred full beards over clean-shaven faces and masculinised over feminised faces. However, none of the experimental treatments influenced the direction of preferences for facial masculinity or beardedness. We also found no association between women's self-reported pathogen disgust and their preferences for facial masculinity. However, there was a weak positive association between moral disgust scores and preferences for facial masculinity, which might reflect conservatism and preferences for gender typicality in faces. Women's preferences for beards were positively associated with their pathogen disgust, which runs contrary to our predictions and may reflect preferences for high quality individuals who can withstand any costs of beardedness, although further replications are necessary before firm conclusions can be made. We conclude that there is little support for pathogenic exposure being a mechanism that underpins women's directional preferences for masculine traits.
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Affiliation(s)
- Toneya L. McIntosh
- School of Psychology, University of Queensland, Brisbane, Queensland, Australia
| | - Anthony J. Lee
- Institute of Neuroscience and Psychology, University of Glasgow, Scotland, United Kingdom
| | - Morgan J. Sidari
- School of Psychology, University of Queensland, Brisbane, Queensland, Australia
| | - Rebecca E. Stower
- School of Psychology, University of Queensland, Brisbane, Queensland, Australia
| | - James M. Sherlock
- School of Psychology, University of Queensland, Brisbane, Queensland, Australia
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Iglesias-Carrasco M, Head ML, Jennions MD, Cabido C. Condition-dependent trade-offs between sexual traits, body condition and immunity: the effect of novel habitats. BMC Evol Biol 2016; 16:135. [PMID: 27329759 PMCID: PMC4915150 DOI: 10.1186/s12862-016-0706-0] [Citation(s) in RCA: 8] [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: 04/07/2016] [Accepted: 06/09/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The optimal allocation of resources to sexual signals and other life history traits is usually dependent on an individual's condition, while variation in the expression of sexual traits across environments depends on the combined effects of local adaptation, mean condition, and phenotypic responses to environment-specific cues that affect resource allocation. A clear contrast can often be drawn between natural habitats and novel habitats, such as forest plantations and urban areas. In some species, males seem to change their sexual signals in these novel environments, but why this occurs and how it affects signal reliability is still poorly understood. RESULTS The relative size of sexual traits and level of immune responses were significantly lower for male palmate newts Lissotriton helveticus caught in pine and eucalyptus plantations compared to those caught in native forests, but there was no habitat-dependent difference in body condition (n = 18 sites, 382 males). The reliability with which sexual traits signalled body condition and immune responses was the same in all three habitats. Finally, we conducted a mesocosm experiment in which males were maintained in pine, eucalypt or oak infused water for 21 days. Males in plantation-like water (pine or eucalypt) showed significantly lower immune responses but no change in body condition. This matches the pattern seen for field-caught males. Unlike field-caught males, however, there was no relationship between water type and relative sexual trait size. CONCLUSIONS Pine and eucalyptus plantations are likely to be detrimental to male palmate newt because they are associated with reduced immune function and smaller sexual traits. This could be because ecological aspects of these novel habitats, such as high water turbidity or changes in male-male competition, drive selection for reduced investment into sexual traits. However, it is more probable that there are differences in the ease of acquisition, hence optimal allocation, of resources among habitats. Our mesocosm experiment also provides some evidence that water toxicity is a causal factor. Our findings offer insights into how plantations affect amphibian life histories, and how novel habitats might generate long-term selection for new resource allocation strategies in native species.
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Affiliation(s)
- Maider Iglesias-Carrasco
- />Department of Evolutionary Ecology, National Museum of Natural Sciences, Spanish National Research Council (CSIC), José Gutiérrez Abascal, 2, 28006 Madrid, Spain
- />Department of Herpetology, Aranzadi Science Society, Alto de Zorroaga, 1, 20014 Donostia-San Sebastián, Spain
| | - Megan L. Head
- />Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT Australia
| | - Michael D. Jennions
- />Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT Australia
| | - Carlos Cabido
- />Department of Herpetology, Aranzadi Science Society, Alto de Zorroaga, 1, 20014 Donostia-San Sebastián, Spain
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14
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Geary DC. Can Neglected Tropical Diseases Compromise Human Wellbeing in Sex-, Age-, and Trait-Specific Ways? PLoS Negl Trop Dis 2016; 10:e0004489. [PMID: 27077746 PMCID: PMC4831682 DOI: 10.1371/journal.pntd.0004489] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Traits that facilitate competition for reproductive resources or that influence mate choice have evolved to signal resilience to infectious disease and other stressors. As a result, the dynamics of competition and choice can, in theory, be used to generate predictions about sex-, age-, and trait-specific vulnerabilities for any sexually reproducing species, including humans. These dynamics and associated vulnerabilities are reviewed for nonhuman species, focusing on traits that are compromised by exposure to parasites. Using the same approach, sex-, age-, and trait-specific vulnerabilities to parasitic disease are illustrated for children's and adolescent's physical growth and fitness. Suggestions are then provided for widening the assessment of human vulnerabilities to include age-appropriate measures of behavioral (e.g., children's play) and cognitive (e.g., language fluency) traits. These are traits that are likely to be compromised by infection in age- and sex-specific ways. Inclusion of these types of measures in studies of neglected tropic diseases has the potential to provide a more nuanced understanding of how these diseases undermine human wellbeing and may provide a useful means to study the efficacy of associated treatments.
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Affiliation(s)
- David C. Geary
- Department of Psychological Sciences, Interdisciplinary Neuroscience, University of Missouri, Columbia, Missouri, United States of America
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15
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Lopez‐Idiaquez D, Vergara P, Fargallo JA, Martinez‐Padilla J. Old males reduce melanin-pigmented traits and increase reproductive outcome under worse environmental conditions in common kestrels. Ecol Evol 2016; 6:1224-35. [PMID: 26941948 PMCID: PMC4761766 DOI: 10.1002/ece3.1910] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/01/2015] [Indexed: 12/31/2022] Open
Abstract
Secondary sexual traits displayed by males and females may have evolved as a signal of individual quality. However, both individual quality and investment on producing or maintaining enhanced sexual traits change as individuals age. At the same time, the costs associated to produce sexual traits might be attenuated or increased if environmental conditions are benign or worse respectively. Accordingly, environmental conditions are expected to shape the association between the expression of sexual traits and their reproductive outcome as individuals age. Nonetheless, little is known about the environmental influence on the co-variation between sexual traits and reproductive outcome throughout the life of individuals. We studied the age-dependency of the number and size of back spots, a melanin-based and sexual trait in adults of common kestrels (Falco tinnunculus). We analysed the age-dependence of reproductive traits and the environmental influence, defined as vole abundance, using a 10-year individual-based dataset. We broke down age-related changes of reproductive traits into within- and between-individual variation to assess their contribution to population-level patterns. Our results showed a within-individual decrease in the number, but not the size, of back spots in males. The size of back spots was positively correlated with food availability in males. Reproductive performance of males increased as they aged, in agreement with the life-history theory but depending of vole abundance. Remarkably, we found that having fewer back spots was positively associated with clutch size only for old individuals under low-food conditions. We suggest that environmental variation may shape the association between the expression of a sexual signal and reproductive outcome. We speculate that the reliability of sexual traits is higher when environmental conditions are poor only for old individuals. Within an evolutionary context, we suggest that the expression of sexual traits might be constrained by environmental conditions at later stages of life.
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Affiliation(s)
- David Lopez‐Idiaquez
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
- Department of EcologyInstituto de Investigación en Recursos Cinegéticos – IRECRonda de Toledos/n. 13005Ciudad RealSpain
| | - Pablo Vergara
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
| | - Juan Antonio Fargallo
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
| | - Jesús Martinez‐Padilla
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
- Research Unit of Biodiversity (OU, CSIC, PA)Oviedo University33600MieresSpain
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16
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Montoya B, Valverde M, Rojas E, Torres R. Oxidative stress during courtship affects male and female reproductive effort differentially in a wild bird with biparental care. J Exp Biol 2016; 219:3915-3926. [DOI: 10.1242/jeb.141325] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 10/03/2016] [Indexed: 12/13/2022]
Abstract
Oxidative stress has been suggested as one of the physiological mechanisms modulating reproductive effort, including investment in mate choice. Here, we evaluated whether oxidative stress influences breeding decisions by acting as a cost of or constraint on reproduction in the brown booby (Sula leucogaster), a long-lived seabird with prolonged biparental care. We found that during courtship, levels of lipid peroxidation (LP) of males and females were positively associated with gular skin color, a trait presumably used in mate choice, while levels of reactive oxygen species (ROS) were higher as laying approached and in early breeding pairs. Evidence of a constraining effect of oxidative stress for females was suggested by the fact that females with higher ROS during courtship laid smaller first eggs and had chicks with lower rates of body mass gain, and higher female LP was associated with lower offspring attendance time. No evidence of an oxidative cost of parental effort was found; from courtship to parental care male and female' ROS decreased, and changes in LP levels were non-significant. Finally, using a cross-fostering experiment we found that offspring ROS was unrelated to rearing and genetic parents' ROS. Interestingly, offspring LP was positively associated with the LP during courtship of both the rearing parents and the genetic father, suggesting that offspring LP might have both a genetic and an environmental component. Hence, in the brown booby oxidative stress may be a cost of investment in reproductive traits before egg laying and constrain females' investment in eggs and parental care.
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Affiliation(s)
- Bibiana Montoya
- Laboratorio de Conducta Animal, Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México
| | - Mahara Valverde
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México
| | - Emilio Rojas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México
| | - Roxana Torres
- Laboratorio de Conducta Animal, Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México
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17
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Wenzel MA, Douglas A, James MC, Redpath SM, Piertney SB. The role of parasite-driven selection in shaping landscape genomic structure in red grouse (Lagopus lagopus scotica). Mol Ecol 2015; 25:324-41. [PMID: 26578090 DOI: 10.1111/mec.13473] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/09/2015] [Accepted: 11/10/2015] [Indexed: 12/25/2022]
Abstract
Landscape genomics promises to provide novel insights into how neutral and adaptive processes shape genome-wide variation within and among populations. However, there has been little emphasis on examining whether individual-based phenotype-genotype relationships derived from approaches such as genome-wide association (GWAS) manifest themselves as a population-level signature of selection in a landscape context. The two may prove irreconcilable as individual-level patterns become diluted by high levels of gene flow and complex phenotypic or environmental heterogeneity. We illustrate this issue with a case study that examines the role of the highly prevalent gastrointestinal nematode Trichostrongylus tenuis in shaping genomic signatures of selection in red grouse (Lagopus lagopus scotica). Individual-level GWAS involving 384 SNPs has previously identified five SNPs that explain variation in T. tenuis burden. Here, we examine whether these same SNPs display population-level relationships between T. tenuis burden and genetic structure across a small-scale landscape of 21 sites with heterogeneous parasite pressure. Moreover, we identify adaptive SNPs showing signatures of directional selection using F(ST) outlier analysis and relate population- and individual-level patterns of multilocus neutral and adaptive genetic structure to T. tenuis burden. The five candidate SNPs for parasite-driven selection were neither associated with T. tenuis burden on a population level, nor under directional selection. Similarly, there was no evidence of parasite-driven selection in SNPs identified as candidates for directional selection. We discuss these results in the context of red grouse ecology and highlight the broader consequences for the utility of landscape genomics approaches for identifying signatures of selection.
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Affiliation(s)
- Marius A Wenzel
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Alex Douglas
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Marianne C James
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Steve M Redpath
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Stuart B Piertney
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
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18
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Wenzel MA, James MC, Douglas A, Piertney SB. Genome-wide association and genome partitioning reveal novel genomic regions underlying variation in gastrointestinal nematode burden in a wild bird. Mol Ecol 2015; 24:4175-92. [PMID: 26179597 DOI: 10.1111/mec.13313] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 06/23/2015] [Accepted: 07/03/2015] [Indexed: 02/06/2023]
Abstract
Identifying the genetic architecture underlying complex phenotypes is a notoriously difficult problem that often impedes progress in understanding adaptive eco-evolutionary processes in natural populations. Host-parasite interactions are fundamentally important drivers of evolutionary processes, but a lack of understanding of the genes involved in the host's response to chronic parasite insult makes it particularly difficult to understand the mechanisms of host life history trade-offs and the adaptive dynamics involved. Here, we examine the genetic basis of gastrointestinal nematode (Trichostrongylus tenuis) burden in 695 red grouse (Lagopus lagopus scotica) individuals genotyped at 384 genome-wide SNPs. We first use genome-wide association to identify individual SNPs associated with nematode burden. We then partition genome-wide heritability to identify chromosomes with greater heritability than expected from gene content, due to harbouring a multitude of additive SNPs with individually undetectable effects. We identified five SNPs on five chromosomes that accounted for differences of up to 556 worms per bird, but together explained at best 4.9% of the phenotypic variance. These SNPs were closely linked to genes representing a range of physiological processes including the immune system, protein degradation and energy metabolism. Genome partitioning indicated genome-wide heritability of up to 29% and three chromosomes with excess heritability of up to 4.3% (total 8.9%). These results implicate SNPs and novel genomic regions underlying nematode burden in this system and suggest that this phenotype is somewhere between being based on few large-effect genes (oligogenic) and based on a large number of genes with small individual but large combined effects (polygenic).
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Affiliation(s)
- Marius A Wenzel
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Marianne C James
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Alex Douglas
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Stuart B Piertney
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
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19
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Wenzel MA, Piertney SB. Digging for gold nuggets: uncovering novel candidate genes for variation in gastrointestinal nematode burden in a wild bird species. J Evol Biol 2015; 28:807-25. [DOI: 10.1111/jeb.12614] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/13/2015] [Accepted: 02/16/2015] [Indexed: 12/16/2022]
Affiliation(s)
- M. A. Wenzel
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen UK
| | - S. B. Piertney
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen UK
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20
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Skrinda I, Krama T, Kecko S, Moore FR, Kaasik A, Meija L, Lietuvietis V, Rantala MJ, Krams I. Body height, immunity, facial and vocal attractiveness in young men. Naturwissenschaften 2014; 101:1017-25. [PMID: 25326093 DOI: 10.1007/s00114-014-1241-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 09/05/2014] [Accepted: 09/09/2014] [Indexed: 02/03/2023]
Abstract
Health, facial and vocal attributes and body height of men may affect a diverse range of social outcomes such as attractiveness to potential mates and competition for resources. Despite evidence that each parameter plays a role in mate choice, the relative role of each and inter-relationships between them, is still poorly understood. In this study, we tested relationships both between these parameters and with testosterone and immune function. We report positive relationships between testosterone with facial masculinity and attractiveness, and we found that facial masculinity predicted facial attractiveness and antibody response to a vaccine. Moreover, the relationship between antibody response to a hepatitis B vaccine and body height was found to be non-linear, with a positive relationship up to a height of 188 cm, but an inverse relationship in taller men. We found that vocal attractiveness was dependent upon vocal masculinity. The relationship between vocal attractiveness and body height was also non-linear, with a positive relationship of up to 178 cm, which then decreased in taller men. We did not find a significant relationship between body height and the fundamental frequency of vowel sounds provided by young men, while body height negatively correlated with the frequency of second formant. However, formant frequency was not associated with the strength of immune response. Our results demonstrate the potential of vaccination research to reveal costly traits that govern evolution of mate choice in humans and the importance of trade-offs among these traits.
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Affiliation(s)
- Ilona Skrinda
- Institute of Systematic Biology, University of Daugavpils, 5401, Daugavpils, Latvia
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21
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Body height affects the strength of immune response in young men, but not young women. Sci Rep 2014; 4:6223. [PMID: 25164474 PMCID: PMC5385821 DOI: 10.1038/srep06223] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/11/2014] [Indexed: 12/05/2022] Open
Abstract
Body height and other body attributes of humans may be associated with a diverse range of social outcomes such as attractiveness to potential mates. Despite evidence that each parameter plays a role in mate choice, we have little understanding of the relative role of each, and relationships between indices of physical appearance and general health. In this study we tested relationships between immune function and body height of young men and women. In men, we report a non-linear relationship between antibody response to a hepatitis-B vaccine and body height, with a positive relationship up to a height of 185 cm, but an inverse relationship in taller men. We did not find any significant relationship between body height and immune function in women. Our results demonstrate the potential of vaccination research to reveal costly traits that govern evolution of mate choice in humans and the importance of trade-offs among these traits.
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22
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Wenzel MA, Piertney SB. Fine-scale population epigenetic structure in relation to gastrointestinal parasite load in red grouse (Lagopus lagopus scotica). Mol Ecol 2014; 23:4256-73. [PMID: 24943398 PMCID: PMC4282444 DOI: 10.1111/mec.12833] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 12/27/2022]
Abstract
Epigenetic modification of cytosine methylation states can be elicited by environmental stresses and may be a key process affecting phenotypic plasticity and adaptation. Parasites are potent stressors with profound physiological and ecological effects on their host, but there is little understanding in how parasites may influence host methylation states. Here, we estimate epigenetic diversity and differentiation among 21 populations of red grouse (Lagopus lagopus scotica) in north-east Scotland and test for association of gastrointestinal parasite load (caecal nematode Trichostrongylus tenuis) with hepatic genome-wide and locus-specific methylation states. Following methylation-sensitive AFLP (MSAP), 129 bands, representing 73 methylation-susceptible and 56 nonmethylated epiloci, were scored across 234 individuals. The populations differed significantly in genome-wide methylation levels and were also significantly epigenetically (FSC = 0.0227; P < 0.001) and genetically (FSC = 0.0058; P < 0.001) differentiated. Parasite load was not associated with either genome-wide methylation levels or epigenetic differentiation. Instead, we found eight disproportionately differentiated epilocus-specific methylation states (FST outliers) using bayescan software and significant positive and negative association of 35 methylation states with parasite load from bespoke generalized estimating equations (GEE), simple logistic regression (sam) and Bayesian environmental analysis (bayenv2). Following Sanger sequencing, genome mapping and geneontology (go) annotation, some of these epiloci were linked to genes involved in regulation of cell cycle, signalling, metabolism, immune system and notably rRNA methylation, histone acetylation and small RNAs. These findings demonstrate an epigenetic signature of parasite load in populations of a wild bird and suggest intriguing physiological effects of parasite-associated cytosine methylation.
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Affiliation(s)
- Marius A Wenzel
- Institute of Biological and Environmental Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
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23
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Martínez-Padilla J, Pérez-Rodríguez L, Mougeot F, Ludwig S, Redpath SM. Intra-sexual competition alters the relationship between testosterone and ornament expression in a wild territorial bird. Horm Behav 2014; 65:435-44. [PMID: 24698833 DOI: 10.1016/j.yhbeh.2014.03.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 03/18/2014] [Accepted: 03/22/2014] [Indexed: 01/21/2023]
Abstract
In a reliable signalling system, individual quality is expected to mediate the costs associated with ornamental displays, with relatively lower costs being paid by individuals of higher quality. These relative costs should depend not only on individual quality, but also on levels of intra-sexual competition. We explored the current and delayed effects that testosterone implants have on bird ornamentation in populations with contrasted population densities, as a proxy for intra-sexual competition. In a replicated experiment, we manipulated testosterone in 196 yearling male red grouse Lagopus lagopus scoticus in autumn in populations of high and low levels of intra-sexual competition. Males were assigned to one of three exogenous testosterone (T) treatments: empty implants (T0), small T implants (T1) or larger T implants (T2). We monitored subsequent changes in testosterone levels, ornament size and carotenoid-based colouration, carotenoid levels and body condition from autumn to spring. Testosterone implants increased testosterone levels, comb redness and comb size, and decreased body condition but these effects depended on levels of intra-sexual competition. Specifically, T2-implanted birds increased testosterone levels and comb size more, and reduced body condition more, in populations where intra-sexual competition was low. In the following spring, testosterone levels of T2-treated birds kept increasing in populations where intra-sexual competition was high but not in populations where intra-sexual competition was low. Our results highlight that levels of intra-sexual competition alter the relationship between testosterone levels and ornament expression, influencing their condition-dependence; they also indicate that the outcome of standard hormone manipulation conducted in free-living animals vary depending on the population context.
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Affiliation(s)
- J Martínez-Padilla
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales, José Gutiérrez Abascal, 2, 23005, Madrid, Spain.
| | - L Pérez-Rodríguez
- Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC, UCLM, JCCM), Ronda de Toledo, s/n, 3005 Ciudad Real, Spain; Department of Evolutionary Ecology, Estación Biológica de Doñana, (EBD-CSIC), Avda. Americo Vespucio, s/n, 41092 Seville, Spain
| | - F Mougeot
- Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC, UCLM, JCCM), Ronda de Toledo, s/n, 3005 Ciudad Real, Spain; Estación Experimental de Zonas Áridas (CSIC), Ctra. de Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain
| | - S Ludwig
- Game & Wildlife Conservation Trust, Eggleston Hall, Barnard Castle, DL12 0AG UK
| | - S M Redpath
- School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
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24
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25
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Butler MW, Karanfilian B, Homsher M, McGraw KJ. Carotenoid supplementation during adulthood, but not development, decreases testis size in mallards. Comp Biochem Physiol A Mol Integr Physiol 2013; 166:465-9. [PMID: 23911982 DOI: 10.1016/j.cbpa.2013.07.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 07/23/2013] [Accepted: 07/23/2013] [Indexed: 01/05/2023]
Abstract
Nutritional constraints on reproduction are well-characterized in female animals, but rarely have particular nutrients been linked to male reproductive investments. Carotenoid pigments promote egg-laying and fertility in several animals, and are displayed externally within secondary sex traits by males of many colorful species to attract mates, but it is unclear if or how carotenoids affect male primary sex traits. We manipulated carotenoid availability in the diet of male mallards (Anas platyrhynchos) during both development and adulthood to determine effects on size and carotenoid content of the testes. We found that developmental carotenoid manipulations did not affect testis size or carotenoid concentration, but that increased carotenoid dietary levels at adulthood resulted in more carotenoid-rich, but smaller, testes. This latter result was surprising, given positive correlations in mammals between testicle size and carotenoid concentration. We also found negative correlations between testis size and carotenoid concentration for individual ducks, regardless of dietary treatment. These results suggest that carotenoid deposition into testis tissue can reduce investment in gonad size (and thus overall sperm count), although the functional consequences of this relationship remain to be tested.
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Affiliation(s)
- Michael W Butler
- Lafayette College, Department of Biology, Easton, PA, 18042-1778, USA; Arizona State University, School of Life Sciences, Tempe, AZ, 85287-4501, USA.
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26
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Warren IA, Gotoh H, Dworkin IM, Emlen DJ, Lavine LC. A general mechanism for conditional expression of exaggerated sexually-selected traits. Bioessays 2013; 35:889-99. [PMID: 23852854 DOI: 10.1002/bies.201300031] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sexually-selected exaggerated traits tend to be unusually reliable signals of individual condition, as their expression tends to be more sensitive to nutritional history and physiological circumstance than that of other phenotypes. As such, these traits are the foundation for many models of sexual selection and animal communication, such as "handicap" and "good genes" models. Exactly how expression of these traits is linked to the bearer's condition has been a central yet unresolved question, in part because the underlying physiological mechanisms regulating their development have remained largely unknown. Recent discoveries across animals as diverse as deer, beetles, and flies now implicate the widely conserved insulin-like signaling pathway, as a common physiological mechanism regulating condition-sensitive structures with extreme growth. This raises the exciting possibility that one highly conserved pathway may underlie the evolution of trait exaggeration in a multitude of sexually-selected signal traits across the animal kingdom.
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Affiliation(s)
- Ian A Warren
- School of Biological Sciences, University of Bristol, UK
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27
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Wenzel MA, Webster LMI, Paterson S, Mougeot F, Martínez-Padilla J, Piertney SB. A transcriptomic investigation of handicap models in sexual selection. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1442-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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28
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Vergara P, Redpath SM, Martínez-Padilla J, Mougeot F. Environmental conditions influence red grouse ornamentation at a population level. Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01974.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pablo Vergara
- School of Biological Sciences; University of Aberdeen; Tillydrone Av.; Aberdeen; AB24 2TZ; UK
| | - Stephen M. Redpath
- School of Biological Sciences; University of Aberdeen & The James Hutton Institute; Aberdeen Centre for Environmental Sustainability (ACES); Tillydrone Av.; Aberdeen; AB24 2TZ; UK
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29
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Vergara P, Martínez-Padilla J. Social context decouples the relationship between a sexual ornament and testosterone levels in a male wild bird. Horm Behav 2012; 62:407-12. [PMID: 22841824 DOI: 10.1016/j.yhbeh.2012.07.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/16/2012] [Accepted: 07/18/2012] [Indexed: 11/19/2022]
Abstract
In order to maximise fitness individuals should adjust their level of signalling according to their surrounding social environment. However, field experiments showing such adjustment of current signalling associated to changes in social context are lacking. Here, we manipulated levels of male aggressive- and dominance-related displays in a wild bird in our treated area by increasing testosterone levels using implants in a subset of males. We then compared the expression of sexual signals (i.e. comb size) between non-treated red grouse Lagopus lagopus scoticus males from control and treatment areas. We further explored the potential endocrinological mechanism linking social environment and signal expression by analysing testosterone levels in all males. Our treatment successfully increased overall aggressive- and dominance-related behaviours in the treatment area. Furthermore, testosterone-implanted birds increased their comb size as repeatedly shown in previous studies in male red grouse. Interestingly, untreated males living in the treatment area decreased their comb size, whilst increasing testosterone levels. Since comb size is a signal of dominance, untreated males from the treatment area may have perceived themselves as subordinate individuals and decreased their signalling levels to avoid confrontations with testosterone-treated, dominant individuals. In conclusion, our findings show that social context has the potential to regulate sexual signalling and testosterone levels. Our results highlight the role of social context when exploring the link between testosterone and behaviour, as it may reverse the relationship between both traits. Our results suggest that social context affects signalling and testosterone independently.
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Affiliation(s)
- Pablo Vergara
- School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
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