1
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Tooth A, Morosinotto C, Karell P. Sex allocation is color morph-specific and associated with fledging condition in a wild bird. Behav Ecol 2024; 35:arae039. [PMID: 38818250 PMCID: PMC11138213 DOI: 10.1093/beheco/arae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 04/03/2024] [Accepted: 05/14/2024] [Indexed: 06/01/2024] Open
Abstract
Melanin-based color polymorphism is predicted to evolve and maintain through differential fitness of morphs in different environments, and several empirical studies indicate that life history strategies, physiology, and behavior vary among color morphs. Sex allocation theory predicts that parents should adjust their sex allocation based on differential costs of raising sons and daughters, and therefore, color morphs are expected to modify their brood sex ratio decisions. In color polymorphic tawny owls (Strix aluco), the pheomelanistic brown morph is associated with higher energy requirements, faster growth, and higher parental effort than the gray morph. As hypothesized, we find that brown tawny owl mothers produced more daughters in early broods and more males in late broods, whereas gray mothers did the opposite. At fledging, daughters of early broods and of brown mothers were heavier than those of late broods or gray mothers. Hence, larger and more costly daughters appeared to benefit more than males from being born to brown mothers early in the season. Brown mothers breeding later in the season produced more cheap sons, while gray mothers face fewer challenges under limited resources and favor daughters. These findings suggest that environmental conditions influence brood sex allocation strategies of genetically determined color morphs differently.
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Affiliation(s)
- Amandine Tooth
- Department of Biology, Lund University, Sölvegatan 37 (Ecology Building), SE-223 62 Lund, Sweden
| | - Chiara Morosinotto
- Department of Biology, Lund University, Sölvegatan 37 (Ecology Building), SE-223 62 Lund, Sweden
- Bioeconomy Research Team, Novia University of Applied Sciences, Raseborgsvägen 9, FI-10600 Raseborg, Finland
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
- National Biodiversity Future Center (NBFC), Piazza Marina 61, I-90133 Palermo, Italy
| | - Patrik Karell
- Department of Biology, Lund University, Sölvegatan 37 (Ecology Building), SE-223 62 Lund, Sweden
- Bioeconomy Research Team, Novia University of Applied Sciences, Raseborgsvägen 9, FI-10600 Raseborg, Finland
- Evolutionary Biology Center, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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2
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Wells CP, Lyon BE, Thow CM, Stair T, Jones M, Hinton M, Eadie JM. Limited evidence of biased offspring sex allocation in a cavity-nesting conspecific brood parasite. Behav Ecol 2024; 35:arae024. [PMID: 39372888 PMCID: PMC11453106 DOI: 10.1093/beheco/arae024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/08/2024] [Accepted: 03/27/2024] [Indexed: 10/08/2024] Open
Abstract
Sex allocation theory predicts that mothers should bias investment in offspring toward the sex that yields higher fitness returns; one such bias may be a skewed offspring sex ratio. Sex allocation is well-studied in birds with cooperative breeding systems, with theory on local resource enhancement and production of helpers at the nest, but little theoretical or empirical work has focused on birds with brood parasitic breeding systems. Wood ducks (Aix sponsa) are a conspecific brood parasite, and rates of parasitism appear to increase with density. Because female wood ducks show high natal philopatry and nest sites are often limiting, local resource competition (LRC) theory predicts that females should overproduce male offspring-the dispersing sex-when competition (density) is high. However, the unique features of conspecific brood parasitism generate alternative predictions from other sex allocation theory, which we develop and test here. We experimentally manipulated nesting density of female wood ducks in 4 populations from 2013 to 2016, and analyzed the resulting sex allocation of >2000 ducklings. In contrast to predictions we did not find overproduction of male offspring by females in high-density populations, females in better condition, or parasitic females; modest support for LRC was found in overproduction of only female parasitic offspring with higher nest box availability. The lack of evidence for sex ratio biases, as expected for LRC and some aspects of brood parasitism, could reflect conflicting selection pressures from nest competition and brood parasitism, or that mechanisms of adaptive sex ratio bias are not possible.
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Affiliation(s)
- Caitlin P Wells
- Department of Fish, Wildlife, and Conservation Biology; Colorado State University, 901 Amy Van Dyken Way, Fort Collins, CO 80523, USA
- Department of Wildlife, Fish, and Conservation Biology; University of California, 1088 Academic Surge, Davis, CA 95616, USA
| | - Bruce E Lyon
- Department of Ecology and Evolution; University of California, UCSC/Coastal Biology Building 130 McAllister Way, Santa Cruz, CA 95060, USA
| | - Caroline M Thow
- Department of Ecology and Evolution; University of California, UCSC/Coastal Biology Building 130 McAllister Way, Santa Cruz, CA 95060, USA
| | - Tez Stair
- Department of Wildlife, Fish, and Conservation Biology; University of California, 1088 Academic Surge, Davis, CA 95616, USA
| | - Melissa Jones
- Department of Wildlife, Fish, and Conservation Biology; University of California, 1088 Academic Surge, Davis, CA 95616, USA
| | - Mitch Hinton
- Department of Wildlife, Fish, and Conservation Biology; University of California, 1088 Academic Surge, Davis, CA 95616, USA
| | - John M Eadie
- Department of Wildlife, Fish, and Conservation Biology; University of California, 1088 Academic Surge, Davis, CA 95616, USA
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3
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Diamond-Smith NG, Epstein A, Zlatnik MG, Treleaven E. The association between timing in pregnancy of drought and excess rainfall, infant sex, and birthweight: Evidence from Nepal. Environ Epidemiol 2023; 7:e263. [PMID: 37840861 PMCID: PMC10569756 DOI: 10.1097/ee9.0000000000000263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 09/26/2022] [Accepted: 06/26/2023] [Indexed: 10/17/2023] Open
Abstract
Background Past research on the impact of climatic events, such as drought, on birth outcomes has primarily been focused in Africa, with less research in South Asia, including Nepal. Existing evidence has generally found that drought impacts birthweight and infant sex, with differences by trimester. Additionally, less research has looked at the impact of excess rain on birth outcomes or focused on the impact of rainfall extremes in the preconception period. Using data from a large demographic surveillance system in Nepal, combined with a novel measure of drought/excess rainfall, we explore the impact of these on birthweight by time in pregnancy. Methods Using survey data from the 2016 to 2019 Chitwan Valley Study in rural Nepal combined with data from Climate Hazards InfraRed Precipitation with Station, we explored the association between excess rainfall and drought and birthweight, looking at exposure in the preconception period, and by trimester of pregnancy. We also explore the impact of excess rainfall and drought on infant sex and delivery with a skilled birth attendant. We used multilevel regressions and explored for effect modification by maternal age. Results Drought in the first trimester is associated with lower birthweight (β = -82.9 g; 95% confidence interval [CI] = 164.7, -1.2) and drought in the preconception period with a high likelihood of having a male (odds ratio [OR] = 1.41; 95% CI = 1.01, 2.01). Excess rainfall in the first trimester is associated with high birthweight (β = 111.6 g; 95% CI = 20.5, 202.7) and higher odds of having a male (OR = 1.48; 95% CI = 1.02, 2.16), and in the third trimester with higher odds of low birth weight (OR = 2.50; 95% CI = 1.40, 4.45). Conclusions Increasing rainfall extremes will likely impact birth outcomes and could have implications for sex ratios at birth.
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Affiliation(s)
- Nadia G. Diamond-Smith
- Department of Epidemiology and Biostatistics and Institute for Global Health Sciences, University of California, San Francisco, San Francisco, California
| | - Adrienne Epstein
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California
| | - Marya G. Zlatnik
- Division of Maternal Fetal Medicine, Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology, & Reproductive Sciences, University of California, San Francisco, San Francisco, California
| | - Emily Treleaven
- Institute for Social Research, University of Michigan, Ann Arbor, Michigan
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4
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Satta V, Pira A, Cherchi S, Nissardi S, Rotta A, Pirastru M, Mereu P, Zedda M, Bogliolo L, Naitana S, Leoni GG. Adaptive Response to Gillnets Bycatch in a North Sardinia Mediterranean Shag ( Gulosus aristotelis desmarestii) Population. Animals (Basel) 2023; 13:2142. [PMID: 37443940 DOI: 10.3390/ani13132142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023] Open
Abstract
Mediterranean Shag (Gulosus aristotelis desmarestii) is a seabird endemic to the Mediterranean and Black Seas, recently included in the IUCN list of threatened Species. Most of the reproductive colonies are hosted in Sardinia and surrounding islets. Bycatch in fishing nets is one of the most significant threats for this population. Our work aimed to assess alterations in the sex ratio caused by bycatch and to study the adaptive response of the population to a skewed adult sex ratio. The sex ratio of Mediterranean Shags found drowned in the gillnets near the colonies and that of the nestlings of the Corcelli (northeast Sardinia) colony was determined using the sex-linked polymorphism of the gene Chromobox-Helicase-DNA-binding 1. The data of the shags found drowned in gillnets evidenced a high mortality rate (83.3%; p < 0.001) and a larger size of males (35% heavier than females, p < 0.05) compared to females, supporting the theory that heavier individuals are able to forage at great depths. With 64.8% of the nestlings being male, the sex ratio of nestlings was statistically different from parity (p < 0.05). Furthermore, it was related to the brood size. In one- and two-chick broods, 73% and 70% of nestlings, respectively, were males, while in three-chick broods, only 33% were males. Our data identify the higher rate of male shags drowned in gillnets as a factor causing an alteration of the sex ratio in the Mediterranean Shag population. According to the Sex Allocation Theory, an adaptive adjustment of sex made by adult females restores the Mendelian sex ratio in the population.
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Affiliation(s)
- Valentina Satta
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Angela Pira
- Acquario di Cala Gonone, Via La Favorita, 08022 Cala Gonone, Italy
| | - Santino Cherchi
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | | | - Andrea Rotta
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Monica Pirastru
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/B, 07100 Sassari, Italy
| | - Paolo Mereu
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/B, 07100 Sassari, Italy
| | - Marco Zedda
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Luisa Bogliolo
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Salvatore Naitana
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Giovanni Giuseppe Leoni
- Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
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5
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Gómez-López G, Martínez F, Sanz-Aguilar A, Carrete M, Blanco G. Nestling sex ratio is unaffected by individual and population traits in the griffon vulture. Curr Zool 2023; 69:227-235. [PMID: 37351302 PMCID: PMC10284052 DOI: 10.1093/cz/zoac046] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 06/07/2022] [Indexed: 10/26/2023] Open
Abstract
Variation in offspring sex ratios is a central topic in animal demography and population dynamics. Most studies have focused on bird species with marked sexual dimorphism and multiple-nestling broods, where the offspring sex ratio is often biased due to different individual or environmental variables. However, biases in offspring sex ratios have been far less investigated in monomorphic and single-egg laying species, and few studies have evaluated long-term and large-scale variations in the sex ratio of nestling vultures. Here, we explore individual and environmental factors potentially affecting the secondary sex ratio of the monomorphic griffon vulture Gyps fulvus. We used information collected at three breeding nuclei from central Spain over a 30-year period (1990-2020) to analyse the effects of nestling age, parental age, breeding phenology, conspecific density, population reproductive parameters, and spatial and temporal variability on nestling sex. Sex ratio did not differ from parity either at the population or the nuclei level. No significant between-year differences were detected, even under highly changing conditions of food availability associated with the mad-cow crisis. We found that tree nesting breeders tend to have more sons than daughters, but as this nesting behavior is rare and we consequently have a small sample size, this issue would require additional examination. Whereas further research is needed to assess the potential effect of breeder identity on nestling sex ratio, this study contributes to understanding the basic ecology and population dynamics of Griffon Vultures, a long-lived species with deferred maturity and low fecundity, whose minor deviations in the offspring sex ratio might imply major changes at the population level.
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Affiliation(s)
- Guillermo Gómez-López
- Department of Evolutionary Ecology, National Museum of Natural Sciences (MNCN), Spanish National Research Council (CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain
| | - Félix Martínez
- Escuela Internacional de Doctorado, Universidad Rey Juan Carlos (URJC), Tulipán s/n, 28933 Móstoles, Madrid, Spain
| | - Ana Sanz-Aguilar
- Animal Demography and Ecology Group, Institut Mediterrani d’Estudis Avançats (IMEDEA), Miquel Marqués 21, 07020 Esporles, Mallorca, Spain
- Applied Zoology and Conservation Group, Universitat de les Illes Balears (UIB), Ctra. De Valldemossa km. 7.5, 07122, Palma, Spain
| | - Martina Carrete
- Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide (UPO), Ctra. de Utrera km. 1, 41013 Sevilla, Spain
| | - Guillermo Blanco
- Department of Evolutionary Ecology, National Museum of Natural Sciences (MNCN), Spanish National Research Council (CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain
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6
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Huang Y, Lo YH, Hsu JC, Le TS, Yang FJ, Chang T, Braendle C, Wang J. Widespread sex ratio polymorphism in Caenorhabditis nematodes. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221636. [PMID: 36938539 PMCID: PMC10014251 DOI: 10.1098/rsos.221636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Although equal sex ratio is ubiquitous and represents an equilibrium in evolutionary theory, biased sex ratios are predicted for certain local conditions. Cases of sex ratio bias have been mostly reported for single species, but little is known about its evolution above the species level. Here, we surveyed progeny sex ratios in 23 species of the nematode genus Caenorhabditis, including 19 for which we tested multiple strains. For the species with multiple strains, five species had female-biased and two had non-biased sex ratios in all strains, respectively. The other 12 species showed polymorphic sex ratios across strains. Female-biased sex ratios could be due to sperm competition whereby X-bearing sperm outcompete nullo-X sperm during fertilization. In this model, when sperm are limited allowing all sperm to be used, sex ratios are expected to be equal. However, in assays limiting mating to a few hours, most strains showed similarly biased sex ratios compared with unlimited mating experiments, except that one C. becei strain showed significantly reduced female bias compared with unlimited mating. Our study shows frequent polymorphism in sex ratios within Caenorhabditis species and that sperm competition alone cannot explain the sex ratio bias.
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Affiliation(s)
- Yun Huang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yun-Hua Lo
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Jung-Chen Hsu
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Tho Son Le
- Department of Molecular Genetics and Gene Technology, College of Forestry Biotechnology, Vietnam National University of Forestry, Hanoi, Vietnam
| | - Fang-Jung Yang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Tiffany Chang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | | | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
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7
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Borger MJ, Richardson DS, Dugdale H, Burke T, Komdeur J. Testing the environmental buffering hypothesis of cooperative breeding in the Seychelles warbler. Acta Ethol 2023. [DOI: 10.1007/s10211-022-00408-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AbstractSpecies are facing environmental challenges caused by rapidly changing environments. Globally, extreme weather events, like droughts or extreme rainfall, are increasing in frequency. Natural selection usually acts slowly, while adaptations through phenotypic plasticity are limited. Therefore, organisms may utilise other mechanisms to cope with such rapid change. Cooperative breeding is hypothesised to be one such mechanism, as helpers could increase survival probabilities of offspring, especially in harsh years. Rainfall is a cue for onset of breeding in many tropical species, to ensure young are born when food abundance is highest. Using 21 years of data, we investigate the effect of rainfall on social behaviour and life history in the insectivorous Seychelles warbler (Acrocephalus sechellensis), a facultative cooperative breeder. We found that low rainfall is associated with reduced reproductive output and possibly with decreased survival. However, there were no statistical differences in response between groups with helpers, groups with only non-helping subordinates, and breeding pairs without subordinates. With low rainfall, more sons (the sex less likely to help) were produced, and those subordinate males already present were less likely to help. Thus, in contrast to expectations, cooperative breeding does not seem to buffer against harsh environments in Seychelles warblers, indicating that group living may be costly and thus not a mechanism for coping with changing environments. Our study showed that the interaction between the environment and life histories, including social behaviour, is complex, but that this interaction is important to consider when studying the impact of changing environments on species survival.
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8
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Brood sex ratio variation in a colonial raptor, the Eleonora's falcon, Falco eleonorae. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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9
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Facultative and persistent offspring sex-ratio bias in relation to the social environment in cooperatively breeding red-winged fairy-wrens (Malurus elegans). Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03221-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Abstract
Females should facultatively bias offspring sex ratio when fitness returns vary among sexes. In cooperative breeders, where individuals help raise others’ young, overproducing the philopatric sex will be adaptive when helpers are absent, whereas overproducing the dispersive sex may be adaptive to reduce intrasexual competition. Thus, fitness returns are expected to vary with the social environment. However, any offspring sex-ratio biases may also result from consistent among-female differences (e.g. quality) and/or environmental variables (e.g. food availability). Yet, few studies have disentangled facultative from persistent biases. We investigated offspring sex-ratio biases in relation to the social environment in cooperatively breeding red-winged fairy-wrens (Malurus elegans). Repeated observations of the same females over nine years allowed for disentanglement of facultative from persistent biases. Females without help did not overproduce daughters, despite female helpers being associated with higher fledgling survival (resource enhancement hypothesis). Instead, females without helpers facultatively overproduced sons —the slower dispersing sex— thereby ensuring long-term helper availability. Furthermore, offspring sex ratio was not biased towards the rarer sex of helpers present in the group or population (resource competition hypothesis). However, females with sex-biased helping produced similarly skewed offspring sex ratios. This among-female association may not be surprising, because helpers are previous seasons’ offspring. Thus, in addition to facultative responses to prevailing social conditions, we found evidence for persistent biases among females. This could potentially explain previous evidence for resource competition/enhancement that have typically been interpreted as facultative responses, highlighting the need for a within-female approach to better understand the adaptiveness of sex-ratio biases.
Significance statement
Under certain conditions, females may benefit from producing a biased offspring sex ratio, but evidence for such effects in vertebrates is weak and inconsistent. Here, using observations of the same females under different social conditions, we show that cooperatively breeding red-winged fairy-wrens facultatively biased offspring sex ratio towards sons when living in pairs, thereby ensuring the availability of a workforce to assist in raising future offspring. However, biased offspring sex ratio patterns may also be the result of consistent differences among females. Indeed, we also found evidence for such patterns and suggest that this could be an explanation for previous findings which are often interpreted as facultative responses.
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10
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Ellis SL, Lohman MG, Sedinger JS, Williams PJ, Riecke TV. Long-term trends and drought: Spatiotemporal variation in juvenile sex ratios of North American ducks. Ecol Evol 2022; 12:e9099. [PMID: 35845362 PMCID: PMC9280441 DOI: 10.1002/ece3.9099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 06/12/2022] [Accepted: 06/20/2022] [Indexed: 11/30/2022] Open
Abstract
Sex ratios affect population dynamics and individual fitness, and changing sex ratios can be indicative of shifts in sex-specific survival at different life stages. While climate and landscape changes alter sex ratios of wild bird populations, long-term, landscape scale assessments of sex ratios are rare. Further, little work has been done to understand changes in sex ratios in avian communities. In this manuscript, we analyze long-term (1961-2015) data on five species of ducks across five broad climatic regions of the United States to estimate the effects of drought and long-term trends on the proportion of juvenile females captured at banding. As waterfowl have a 1:1 sex ratio at hatch, we interpret changes in sex ratios of captured juveniles as changes in sex-specific survival rates during early life. Seven of 12 species-region pairs exhibited evidence for long-term trends in the proportion of juvenile females at banding. The proportion of juvenile females at banding increased for duck populations in the western United States and typically declined for duck populations in the eastern United States. We only observed evidence for an effect of drought in two of the 12 species-region pairs, where the proportion of females declined during drought. As changes to North American landscapes and climate continue and intensify, we expect continued changes in sex-specific juvenile survival rates. More broadly, we encourage further research examining the mechanisms underlying long-term trends in juvenile sex ratios in avian communities.
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Affiliation(s)
- Sage L. Ellis
- Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoNevadaUSA
| | - Madeleine G. Lohman
- Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoNevadaUSA
- Program in Ecology, Evolution, and Conservation BiologyUniversity of NevadaRenoNevadaUSA
| | - James S. Sedinger
- Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoNevadaUSA
| | - Perry J. Williams
- Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoNevadaUSA
| | - Thomas V. Riecke
- Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoNevadaUSA
- Program in Ecology, Evolution, and Conservation BiologyUniversity of NevadaRenoNevadaUSA
- Swiss Ornithological InstituteSempachSwitzerland
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11
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Supergenes, supergenomes, and complex social traits. Proc Natl Acad Sci U S A 2022; 119:2118971118. [PMID: 34987104 PMCID: PMC8764664 DOI: 10.1073/pnas.2118971118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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12
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Bouffet-Halle A, Yang W, Gardner MG, Whiting MJ, Wapstra E, Uller T, While GM. Characterisation and cross-amplification of sex-specific genetic markers in Australasian Egerniinae lizards and their implications for understanding the evolution of sex determination and social complexity. AUST J ZOOL 2022. [DOI: 10.1071/zo21023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Harvey K, Lavretsky P, Foth J, Williams CK. Nest parasitism, promiscuity, and relatedness among wood ducks. PLoS One 2021; 16:e0257105. [PMID: 34855769 PMCID: PMC8639054 DOI: 10.1371/journal.pone.0257105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/23/2021] [Indexed: 11/19/2022] Open
Abstract
Nest parasitism is a common reproductive strategy used by many species of cavity nesting birds. Among these, the wood duck (Aix sponsa) is known to have evolved very specific strategies of when and whom to parasitize that is often based on population and/or environmental queues. Here, we investigated the genetic relationship of two female wood ducks competing over an artificial nesting box in Delaware, including the continued incubation of one female despite the death and body remains of the other female throughout the incubation process. We test whether such an extreme case of nest parasitism can be explained by relatedness, egg lineage composition, or a combination of other factors. To do so, we extracted genomic DNA from blood and tissue of the females, as well as chorioallantoic membranes of all viable and inviable eggs. Subsequently, we assessed relatedness among females and eggs based on hundreds of nuclear loci and the mitochondrial control region. We concluded that (1) the two incubating females were entirely unrelated, (2) the single clutch is in fact represented by a minimum of four unrelated females, and (3) a single female can lay eggs sired by different males. The latter finding is the first direct evidence for successful extra-pair copulation in wood ducks. With decreasing costs and increasing effectiveness, genomic methods have the potential to provide important insights into more complex ecological and evolutionary tactics of such populations.
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Affiliation(s)
- Kayla Harvey
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, New York, United States of America
- Delaware Department of Natural Resources and Environmental Control–Division of Fish & Wildlife, Dover, Delaware, United States of America
| | - Philip Lavretsky
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Justyn Foth
- Delaware Department of Natural Resources and Environmental Control–Division of Fish & Wildlife, Dover, Delaware, United States of America
- Division of Bird Habitat Conservation, United States Fish and Wildlife Service, Falls Church, Virginia, United States of America
| | - Christopher K. Williams
- Delaware Department of Natural Resources and Environmental Control–Division of Fish & Wildlife, Dover, Delaware, United States of America
- Department of Entomology and Wildlife Ecology, University of Delaware, Newark, Delaware, United States of America
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14
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Lagunas-Robles G, Purcell J, Brelsford A. Linked supergenes underlie split sex ratio and social organization in an ant. Proc Natl Acad Sci U S A 2021; 118:e2101427118. [PMID: 34772805 PMCID: PMC8609651 DOI: 10.1073/pnas.2101427118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2021] [Indexed: 12/19/2022] Open
Abstract
Sexually reproducing organisms usually invest equally in male and female offspring. Deviations from this pattern have led researchers to new discoveries in the study of parent-offspring conflict, genomic conflict, and cooperative breeding. Some social insect species exhibit the unusual population-level pattern of split sex ratio, wherein some colonies specialize in the production of future queens and others specialize in the production of males. Theoretical work predicted that worker control of sex ratio and variation in relatedness asymmetry among colonies would cause each colony to specialize in the production of one sex. While some empirical tests supported theoretical predictions, others deviated from them, leaving many questions about how split sex ratio emerges. One factor yet to be investigated is whether colony sex ratio may be influenced by the genotypes of queens or workers. Here, we sequence the genomes of 138 Formica glacialis workers from 34 male-producing and 34 gyne-producing colonies to determine whether split sex ratio is under genetic control. We identify a supergene spanning 5.5 Mbp that is closely associated with sex allocation in this system. Strikingly, this supergene is adjacent to another supergene spanning 5 Mbp that is associated with variation in colony queen number. We identify a similar pattern in a second related species, Formica podzolica. The discovery that split sex ratio is determined, at least in part, by a supergene in two species opens future research on the evolutionary drivers of split sex ratio.
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Affiliation(s)
- German Lagunas-Robles
- Department of Evolution, Ecology and Organismal Biology, University of California, Riverside, CA 92521
| | - Jessica Purcell
- Department of Entomology, University of California, Riverside, CA 92521
| | - Alan Brelsford
- Department of Evolution, Ecology and Organismal Biology, University of California, Riverside, CA 92521;
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15
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Iritani R, West SA, Abe J. Cooperative interactions among females can lead to even more extraordinary sex ratios. Evol Lett 2021; 5:370-384. [PMID: 34367662 PMCID: PMC8327954 DOI: 10.1002/evl3.217] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/04/2021] [Accepted: 01/15/2021] [Indexed: 11/29/2022] Open
Abstract
Hamilton's local mate competition theory provided an explanation for extraordinary female-biased sex ratios in a range of organisms. When mating takes place locally, in structured populations, a female-biased sex ratio is favored to reduce competition between related males, and to provide more mates for males. However, there are a number of wasp species in which the sex ratios appear to more female biased than predicted by Hamilton's theory. It has been hypothesized that the additional female bias in these wasp species results from cooperative interactions between females. We investigated theoretically the extent to which cooperation between related females can interact with local mate competition to favor even more female-biased sex ratios. We found that (i) cooperation between females can lead to sex ratios that are more female biased than predicted by local competition theory alone, and (ii) sex ratios can be more female biased when the cooperation occurs from offspring to mothers before dispersal, rather than cooperation between siblings after dispersal. Our models formally confirm the verbal predictions made in previous experimental studies, which could be applied to a range of organisms. Specifically, cooperation can help explain sex ratio biases in Sclerodermus and Melittobia wasps, although quantitative comparisons between predictions and data suggest that some additional factors may be operating.
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Affiliation(s)
- Ryosuke Iritani
- Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS)RIKENWako351‐0198Japan
| | - Stuart A. West
- Department of ZoologyUniversity of OxfordOxfordOX1 3PSUnited Kingdom
| | - Jun Abe
- Faculty of Liberal ArtsMeiji Gakuin UniversityYokohama244–8539Japan
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16
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Abe J, Iritani R, Tsuchida K, Kamimura Y, West SA. A solution to a sex ratio puzzle in Melittobia wasps. Proc Natl Acad Sci U S A 2021; 118:e2024656118. [PMID: 33972440 PMCID: PMC8157915 DOI: 10.1073/pnas.2024656118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The puzzling sex ratio behavior of Melittobia wasps has long posed one of the greatest questions in the field of sex allocation. Laboratory experiments have found that, in contrast to the predictions of theory and the behavior of numerous other organisms, Melittobia females do not produce fewer female-biased offspring sex ratios when more females lay eggs on a patch. We solve this puzzle by showing that, in nature, females of Melittobia australica have a sophisticated sex ratio behavior, in which their strategy also depends on whether they have dispersed from the patch where they emerged. When females have not dispersed, they lay eggs with close relatives, which keeps local mate competition high even with multiple females, and therefore, they are selected to produce consistently female-biased sex ratios. Laboratory experiments mimic these conditions. In contrast, when females disperse, they interact with nonrelatives, and thus adjust their sex ratio depending on the number of females laying eggs. Consequently, females appear to use dispersal status as an indirect cue of relatedness and whether they should adjust their sex ratio in response to the number of females laying eggs on the patch.
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Affiliation(s)
- Jun Abe
- Faculty of Liberal Arts, Meijigakuin University, Yokohama, Kanagawa 244-8539, Japan;
- Research Institute for Integrated Science, Kanagawa University, Hiratsuka, Kanagawa 159-1293, Japan
| | - Ryosuke Iritani
- RIKEN Interdisciplinary Theoretical and Mathematical Sciences, Wako, Saitama 351-0198, Japan
| | - Koji Tsuchida
- Faculty of Applied Biological Sciences, Gifu University, 501-1193 Gifu, Japan
| | - Yoshitaka Kamimura
- Department of Biology, Keio University, Yokohama, Kanagawa 223-8521, Japan
| | - Stuart A West
- Department of Zoology, Oxford University, OX1 3SZ Oxford, United Kingdom
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Pierron F, Lorioux S, Héroin D, Daffe G, Etcheverria B, Cachot J, Morin B, Dufour S, Gonzalez P. Transgenerational epigenetic sex determination: Environment experienced by female fish affects offspring sex ratio. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 277:116864. [PMID: 33714788 DOI: 10.1016/j.envpol.2021.116864] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 02/22/2021] [Accepted: 02/27/2021] [Indexed: 06/12/2023]
Abstract
Sex determination is a complex process that can be influenced by environment in various taxa. Disturbed environments can affect population sex ratios and thus threaten their viability. Emerging evidences support a role of epigenetic mechanisms, notably DNA methylation, in environmental sex determination (ESD). In this work, using zebrafish as model and a transgenerational experiment comprising 4 successive generations, we report a strength link between the promotor methylation level of three genes in female gonads and population sex ratio. One generation of zebrafish was exposed throughout its lifetime to cadmium (Cd), a non-essential metal, at an environmentally relevant concentration. The subsequent generations were not exposed. At the first and the third generation a subset of individuals was exposed to an elevated temperature, a well-known masculinizing factor in zebrafish. While heat was associated to an increase in the methylation level of cyp19a1a gene and population masculinization, foxl2a/dmrt1 methylation levels appeared to be influenced by Cd and fish density leading to offspring feminization. Ancestral Cd exposure indeed led to a progressive feminization of the population over generations and affected the sex plastic response of zebrafish in response to heat. The effect of Cd on the methylation level of foxl2a was observed until the third generation, supporting potential transgenerational inheritance. Our results support (i) a key role of cyp19a1a methylation in SD in zebrafish in response to environmental cues and (ii) the fact that the environment experienced by parents, namely mothers in the present case, can affect their offspring sex ratio via environment-induced DNA methylation changes in gonads.
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Affiliation(s)
- Fabien Pierron
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600, Pessac, France.
| | - Sophie Lorioux
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600, Pessac, France
| | - Débora Héroin
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600, Pessac, France
| | - Guillemine Daffe
- Univ. Bordeaux, CNRS, INRAE, La Rochelle Univ., UMS 2567 POREA, F-33615, Pessac, France
| | | | - Jérôme Cachot
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600, Pessac, France
| | - Bénédicte Morin
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600, Pessac, France
| | - Sylvie Dufour
- Laboratory Biology of Aquatic Organisms and Ecosystems (BOREA), Muséum National D'Histoire Naturelle, CNRS, IRD, Sorbonne Université, Université de Caen Normandie, Université des Antilles, 75231, Paris Cedex, 05, France
| | - Patrice Gonzalez
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600, Pessac, France
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BARTLOW ANDREWW, JANKOWSKI MARKD, HATHCOCK CHARLESD, RYTI RANDALLT, RENEAU STEVENL, FAIR JEANNEM. Sex ratio of Western Bluebirds Sialia mexicana is mediated by phenology and clutch size. THE IBIS 2021; 163:977-989. [PMID: 35801167 PMCID: PMC9257600 DOI: 10.1111/ibi.12935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 01/25/2021] [Indexed: 06/15/2023]
Abstract
Mothers may produce more of one sex to maximize their fitness if there are differences in the cost of producing each sex or there are differences in their relative reproductive value. Breeding date and clutch size are known to influence offspring sex ratios in birds through sex differences in dispersal, social behaviours, differential mortality, and available food resources. We tested if breeding date, clutch size and drought conditions influenced offspring sex ratios in a sexually size-monomorphic species, the Western Bluebird, by interrogating a 21-year dataset. After controlling for differential mortality, we found that hatch dates late in the breeding season were associated with the production of more females, suggesting that the value of producing males declines as the breeding season progresses. When clutch size was taken into account, small clutches yielded significantly more females late in the breeding season compared to the early and middle parts of the breeding season that produced significantly more males. Large clutches early in the season tended to produce more females, although this was not significant. Drought severity was not correlated with sex ratio adjustment. We propose and discuss several explanations for these patterns, including male offspring, but not female offspring, acting as helpers, increased female nestling provisioning late in the breeding season, differences in food abundance, and egg-laying order. Future work will help to uncover the mechanisms leading to these patterns. Identifying patterns and mechanisms of sex ratio skew from long-term datasets is important for informing predictions regarding life-history trade-offs in wildlife populations.
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Affiliation(s)
- ANDREW W. BARTLOW
- Los Alamos National Laboratory, Biosecurity and Public Health, Mailstop M888, Los Alamos, NM 87545, USA
| | - MARK D. JANKOWSKI
- Laboratory Services and Applied Science Division, U.S. Environmental Protection Agency, 1200 6 Avenue, Suite 900, Seattle, WA 98101, USA
| | - CHARLES D. HATHCOCK
- Los Alamos National Laboratory, Environmental Stewardship, Los Alamos, NM 87545, USA
| | - RANDALL T. RYTI
- Neptune and Company, Inc., 1505 15th St #B, Los Alamos, NM 87544, USA
| | - STEVEN L. RENEAU
- Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545
| | - JEANNE M. FAIR
- Los Alamos National Laboratory, Biosecurity and Public Health, Mailstop M888, Los Alamos, NM 87545, USA
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Mermoz ME, Villarruel C, de la Colina A, Mahler B. Fledgling sex-ratio is biased towards the helping sex in a Neotropical cooperative breeder, the brown-and-yellow marshbird (Pseudoleistes virescens). BEHAVIOUR 2021. [DOI: 10.1163/1568539x-bja10061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
In many cooperatively breeding species, helpers increase the breeding success of their parents. The repayment hypothesis predicts a skewed sex-ratio towards the helping sex at population level; at individual level bias would increase in broods attended by a smaller number of helpers. We studied a brown-and-yellow marshbird (Pseudoleistes virescens) population during 11 breeding seasons. We found that 90% of helpers were males and that they increased nestling survival, although this effect disappeared in presence of parasitic shiny cowbirds. Helpers sometimes helped at nests of adults other than their parents. Population sex-ratio of fledglings was highly skewed towards males (1.4:1). At individual level, male-biased sex-ratio of fledglings was more pronounced early in the season and increased with brood losses but was not affected by number of helpers. Marshbirds feed at communal areas so retaining helpers would not be costly. Therefore, a general skew towards males might be the best adaptive strategy.
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Affiliation(s)
- Myriam E. Mermoz
- Instituto de Ecología, Genética, y Evolución de Buenos Aires (UBA-CONICET), Intendente Güiraldes 2160 — Ciudad Universitaria — C1428EGA, CABA, Argentina
- Departamento de Ecología, Genética, y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
| | - Cecilia Villarruel
- Departamento de Ecología, Genética, y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
- Current address: Instituto de Fisiología, Biología Molecular y Neurociencias (UBA-CONICET), Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
| | - Alicia de la Colina
- Instituto de Ecología, Genética, y Evolución de Buenos Aires (UBA-CONICET), Intendente Güiraldes 2160 — Ciudad Universitaria — C1428EGA, CABA, Argentina
- Current address: Departamento de Conservación e Investigación, Fundación Temaikèn — B1625 Escobar, Prov. de Buenos Aires, Argentina
| | - Bettina Mahler
- Instituto de Ecología, Genética, y Evolución de Buenos Aires (UBA-CONICET), Intendente Güiraldes 2160 — Ciudad Universitaria — C1428EGA, CABA, Argentina
- Departamento de Ecología, Genética, y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
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20
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Kappeler PM. Parental Care. Anim Behav 2021. [DOI: 10.1007/978-3-030-82879-0_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Firman RC, Tedeschi JN, Garcia-Gonzalez F. Sperm sex ratio adjustment in a mammal: perceived male competition leads to elevated proportions of female-producing sperm. Biol Lett 2020; 16:20190929. [PMID: 32486939 DOI: 10.1098/rsbl.2019.0929] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mammal sex allocation research has focused almost exclusively on maternal traits, but it is now apparent that fathers can also influence offspring sex ratios. Parents that produce female offspring under conditions of intense male-male competition can benefit with greater assurance of maximized grand-parentage. Adaptive adjustment in the sperm sex ratio, for example with an increase in the production of X-chromosome bearing sperm (CBS), is one potential paternal mechanism for achieving female-biased sex ratios. Here, we tested this mechanistic hypothesis by varying the risk of male-male competition that male house mice perceived during development, and quantifying sperm sex ratios at sexual maturity. Our analyses revealed that males exposed to a competitive 'risk' produced lower proportions of Y-CBS compared to males that matured under 'no risk' of competition. We also explored whether testosterone production was linked to sperm sex ratio variation, but found no evidence to support this. We discuss our findings in relation to the adaptive value of sperm sex ratio adjustments and the role of steroid hormones in socially induced sex allocation.
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Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Jamie N Tedeschi
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Francisco Garcia-Gonzalez
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.,Estacion Biológica de Doñana, CSIC, Sevilla, Spain
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22
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Firman RC. Exposure to high male density causes maternal stress and female-biased sex ratios in a mammal. Proc Biol Sci 2020; 287:20192909. [PMID: 32370673 PMCID: PMC7282911 DOI: 10.1098/rspb.2019.2909] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 04/14/2020] [Indexed: 12/29/2022] Open
Abstract
A shift from the traditional perspective that maternal stress is invariably costly has instigated recent interest into its adaptive role in offspring sex allocation. Stress generated by social instability has been linked to offspring sex ratio biases that favour the production of female offspring, which converges with the theoretical prediction that mothers in the poor condition are better off investing in daughters rather than sons. However, previous research has failed to disentangle two different processes: the passive consequence of maternal stress on sex-specific mortality and the adaptive effect of maternal stress at the time of conception. Here, I show that exposure to high male density social conditions leads to elevated stress hormone levels and female-biased in utero offspring sex ratios in house mice (Mus musculus domesticus), and identify that sex-specific offspring production-not sex-specific mortality-is the mechanism accounting for these sex ratio skews. This outcome reflects the optimal fitness scenario for mothers in a male-dominated environment: the production of daughters, who are guaranteed high mate availability, minimizes male-male competition for their sons. Overall, this study supports the idea that maternal stress has the potential to be adaptive and advances our understanding of how exposure to different social conditions can influence sex allocation in mammals.
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Affiliation(s)
- Renée C. Firman
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
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23
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Wrobel ER, Molina E, Khan NY, Akingbemi BT, Mendonca MT, Navara KJ. Androgen and mineralocorticoid receptors are present on the germinal disc region in laying hens: Potential mediators of sex ratio adjustment in birds? Gen Comp Endocrinol 2020; 287:113353. [PMID: 31809721 DOI: 10.1016/j.ygcen.2019.113353] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/26/2019] [Accepted: 12/01/2019] [Indexed: 11/21/2022]
Abstract
Female birds skew offspring sex ratios based on environmental and social stimuli; however, the mechanism mediating this phenomenon remains unknown. Growing evidence suggests that testosterone and corticosterone may influence meiosis, as they skew sex ratios when given immediately before chromosomal segregation. It is unclear if these hormones act on the germinal disc (GD) or through a downstream mediator. It is also unknown whether the GD contains receptors for these hormones. If testosterone and/or corticosterone act on the GD to skew sex ratios, then the GD should have receptors for them and that receptor levels should be higher in the GD regions compared to other follicular regions. Furthermore, fluctuations of receptor levels should occur near meiotic segregation. We collected ovarian follicles at 5 h pre-ovulation (just before meiotic segregation) and 20 h pre-ovulation (when sex chromosomes are arrested), and measured androgen receptor (AR) and mineralocorticoid receptor (MR) protein levels via Western blot. ARs and MRs were on the follicle in the GD and non-GD regions, and at 5 h and 20 h pre-ovulation. Both AR and MR protein levels were higher in the GD region than the non-GD region at both time points, but did not differ between time points. These results suggest that hen ovarian follicles have receptors for testosterone and corticosterone, and that the ability for testosterone to respond may be specifically higher in the GD-region, providing further support for the role of testosterone in the alteration of meiotic segregation.
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Affiliation(s)
- Elizabeth R Wrobel
- Poultry Science Department, University of Georgia, 203 Poultry Science Bldg., Athens, GA 30602, USA.
| | - Erica Molina
- Biological Sciences Department, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA
| | - Nicola Y Khan
- School of Psychology and Neuroscience, University of St. Andrews, South Street, St. Andrews KY16 9JP, Scotland, UK
| | - Benson T Akingbemi
- Department of Anatomy, Physiology and Pharmacology, Auburn University, 109 Greene Hall, College of Veterinary Medicine, Auburn, AL 36849, USA
| | - Mary T Mendonca
- Biological Sciences Department, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA
| | - Kristen J Navara
- Poultry Science Department, University of Georgia, 203 Poultry Science Bldg., Athens, GA 30602, USA
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24
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Lavoie MD, Tedeschi JN, Garcia‐Gonzalez F, Firman RC. Exposure to male-dominated environments during development influences sperm sex ratios at sexual maturity. Evol Lett 2019; 3:392-402. [PMID: 31388448 PMCID: PMC6675145 DOI: 10.1002/evl3.123] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/15/2019] [Accepted: 05/21/2019] [Indexed: 11/18/2022] Open
Abstract
Different stages during development are important when it comes to phenotypic adjustments in response to external stimuli. Critical stages in mammals are the prenatal phase, where embryos are exposed to a milieu of sex steroid hormones, and the early-postnatal phase, where littermates interact and experience their incipient social environment. Further, the postmaternal environment will influence the development of traits that are linked to reproductive success in adulthood. Accumulated evidence of male-driven sex allocation establishes the currently untested hypothesis that the sperm sex ratio is a plastic trait that can be mediated to align with prevailing social conditions. Here, we used natural variation in the maternal environment and experimentally manipulated the postmaternal environment to identify the importance of these developmental phases on sperm sex ratio adjustments in wild house mice (Mus musculus domesticus). We found that male density in both environments was predictive of sperm sex ratios at sexual maturity: males from more male-biased litters and males maturing under high male density produced elevated levels of Y-chromosome-bearing sperm. Our findings indicate that the sperm sex ratio is a variable phenotypic trait that responds to the external environment, and highlight the potential that these adjustments function as a mechanism of male-driven sex allocation.
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Affiliation(s)
- Misha D. Lavoie
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
| | - Jamie N. Tedeschi
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
| | - Francisco Garcia‐Gonzalez
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
- Estacion Biológica de DoñanaCSICSevillaSpain
| | - Renée C. Firman
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
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25
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Page AE, Myers S, Dyble M, Migliano AB. Why so many Agta boys? Explaining 'extreme' sex ratios in Philippine foragers. EVOLUTIONARY HUMAN SCIENCES 2019; 1:e5. [PMID: 37588404 PMCID: PMC10427305 DOI: 10.1017/ehs.2019.4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Male-biased sex ratios have been observed in multiple small-scale societies. Although intentional and systematic female-biased mortality has been posited as an explanation, there is often a lack of ethnographic evidence of systematic female neglect and/or infanticide. The Agta, a foraging population from the Philippines, have a skewed sex ratio of 1.29 (129 males per 100 females) aged 15 years or under. We hypothesised that this skew was not caused by greater female deaths, but due to an adaptive response, where more males were produced at birth in reaction to high male-biased extrinsic mortality. To test this hypothesis we utilise census, childcare and mortality data from 915 Agta. The Agta's sex ratio is significantly male-biased in the <1 (n = 48, 2:1) and 1-5 year (n = 170, 1.39:1) age cohorts; however, we find no evidence of systematic female neglect in patterns of childcare. Furthermore, the sex ratio decreases over cohorts, becoming balanced by the end of the juvenile period, owing to significantly higher male mortality. Taken together, these results are not supportive of female infanticide or neglect, and instead suggest an adaptive mechanism, acting in utero as a response to male-biased juvenile mortality, following Fisherian principles of equalising parental investment.
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Affiliation(s)
- Abigail E. Page
- Department of Anthropology, University College London, London, UK
- Department of Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Sarah Myers
- Department of Anthropology, University College London, London, UK
| | - Mark Dyble
- Jesus College, University of Cambridge, Cambridge, UK
| | - Andrea Bamberg Migliano
- Department of Anthropology, University College London, London, UK
- Department of Anthropology, University of Zurich, Zurich, Switzerland
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26
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Li J, Wang Y, Lv L, Wang P, Hatchwell BJ, Zhang Z. Context-dependent strategies of food allocation among offspring in a facultative cooperative breeder. Behav Ecol 2019. [DOI: 10.1093/beheco/arz037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Natural selection should favor adoption of parental strategies that maximize fitness when allocating investment among offspring. In birds, begging displays often convey information of nestling need and quality, allowing parents to make adaptive food allocation decisions. We investigated how adults utilized cues likely to represent nestling competitive ability (begging position) and need (begging intensity) and a cue independent of nestling control (nestling sex) to distribute food among nestlings in a facultative cooperative breeder, the black-throated tit (Aegithalos concinnus). We found that parents reduced their efforts when helped, suggesting that parents of helped broods would have the potential to satisfy nestling needs more than unhelped parents. This suggestion was supported by the fact that nestling mass increased faster in helped than in unhelped nests. We found no effect of nestling sex on food allocation, but, as predicted, we found that adults responded differently to begging signals in relation to the presence of helpers and brood size. First, helped parents were more responsive to nestling begging intensity than parents without helpers. Second, female parents and helpers had a stronger preference for nestling begging position in large than in small broods. Third, the preference for nestling begging position was greater for unhelped than for helped female parents. These results provide evidence that carers adjust their preference for different offspring begging signals based on availability of food resources.
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Affiliation(s)
- Jianqiang Li
- School of Nature Conservation, Beijing Forestry University, Beijing, China
| | - Yong Wang
- Department of Biological and Environmental Sciences, School of Agricultural, Life and Natural Sciences, Alabama A&M University, Normal, AL, USA
| | - Lei Lv
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Pengcheng Wang
- Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Ben J Hatchwell
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Zhengwang Zhang
- Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
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27
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Merkling T, Hatch SA, Leclaire S, Danchin E, Blanchard P. Offspring sex-ratio and environmental conditions in a seabird with sex-specific rearing costs: a long-term experimental approach. Evol Ecol 2019. [DOI: 10.1007/s10682-019-09983-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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28
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Szász E, Garamszegi LZ, Rosivall B. What is behind the variation in mate quality dependent sex ratio adjustment? - A meta-analysis. OIKOS 2019. [DOI: 10.1111/oik.05157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Eszter Szász
- Dept of Systematic Zoology and Ecology, Eötvös Loránd Univ; Pázmány Péter sétány 1/C HU-1117 Budapest Hungary
| | - László Zsolt Garamszegi
- Depto de Ecología Evolutiva, Estación Biológica de Donaña-CSIC; Sevilla España
- MTA-ELTE-Theoretical Biology and Evolutionary Ecology Research Group, Eötvös Loránd Univ; Budapest Hungary
| | - Balázs Rosivall
- Dept of Systematic Zoology and Ecology, Eötvös Loránd Univ; Pázmány Péter sétány 1/C HU-1117 Budapest Hungary
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29
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Santi M, Picchi L, Lorenzi MC. Dynamic modulation of reproductive strategies in a simultaneous hermaphrodite and preference for the male role. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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30
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Khwaja N, Preston SAJ, Briskie JV, Hatchwell BJ. Testing the predictions of sex allocation hypotheses in dimorphic, cooperatively breeding riflemen. Ecol Evol 2018; 8:3693-3701. [PMID: 29686850 PMCID: PMC5901175 DOI: 10.1002/ece3.3934] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/08/2018] [Accepted: 01/23/2018] [Indexed: 11/29/2022] Open
Abstract
Evolutionary theory predicts that parents should invest equally in the two sexes. If one sex is more costly, a production bias is predicted in favour of the other. Two well‐studied causes of differential costs are size dimorphism, in which the larger sex should be more costly, and sex‐biased helping in cooperative breeders, in which the more helpful sex should be less costly because future helping “repays” some of its parents’ investment. We studied a bird species in which both processes should favor production of males. Female riflemen Acanthisitta chloris are larger than males, and we documented greater provisioning effort in more female‐biased broods indicating they are likely costlier to raise. Riflemen are also cooperative breeders, and males provide more help than females. Contrary to expectations, we observed no male bias in brood sex ratios, which did not differ significantly from parity. We tested whether the lack of a population‐wide pattern was a result of facultative sex allocation by individual females, but this hypothesis was not supported either. Our results show an absence of adaptive patterns despite a clear directional hypothesis derived from theory. This appears to be associated with a suboptimal female‐biased investment ratio. We conclude that predictions of adaptive sex allocation may falter because of mechanistic constraint, unrecognized costs and benefits, or weak selection.
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Affiliation(s)
- Nyil Khwaja
- Department of Animal & Plant Sciences University of Sheffield Sheffield UK
| | | | - James V Briskie
- School of Biological Sciences University of Canterbury Christchurch New Zealand
| | - Ben J Hatchwell
- Department of Animal & Plant Sciences University of Sheffield Sheffield UK
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31
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Kato T, Matsui S, Terai Y, Tanabe H, Hashima S, Kasahara S, Morimoto G, Mikami OK, Ueda K, Kutsukake N. Male-specific mortality biases secondary sex ratio in Eurasian tree sparrows Passer montanus. Ecol Evol 2017; 7:10675-10682. [PMID: 29299247 PMCID: PMC5743541 DOI: 10.1002/ece3.3575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 11/10/2022] Open
Abstract
Sex allocation theory predicts that parents bias the offspring sex ratio strategically. In avian species, the offspring sex ratio can be biased at multiple growth stages, although the mechanisms are not well known. It is crucial to reveal a cause and timing of biased offspring sex ratio. We investigated (i) offspring sex ratio at multiple growth stages, from laying to fledging; and (ii) the stage at which offspring sex ratio became biased; and (iii) the cause of biased offspring sex ratio in Eurasian tree sparrows Passer montanus. Sex determination of 218 offspring, including hatchlings and unhatched eggs from 41 clutches, suggested that the offspring sex ratio was not biased at the egg‐laying stage but was significantly female‐biased after the laying stage due to higher mortality of male embryos. Half of the unhatched eggs showed no sign of embryo development (37/74, 50.00%), and most undeveloped eggs were male (36/37, 97.30%). Additional experiments using an incubator suggested that the cause of embryo developmental failure was a lack of developmental ability within the egg, rather than a failure of incubation. This study highlights the importance of clarifying offspring sex ratio at multiple stages and suggests that offspring sex ratio is adjusted after fertilization.
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Affiliation(s)
- Takahiro Kato
- Department of Evolutionary Studies of Biosystems School of Advanced Sciences SOKENDAI (The Graduate University for Advanced Studies) Hayama Japan
| | - Shin Matsui
- Department of Biology School of Biological Sciences Tokai Univerrsity Sapporo Japan
| | - Yohey Terai
- Department of Evolutionary Studies of Biosystems School of Advanced Sciences SOKENDAI (The Graduate University for Advanced Studies) Hayama Japan
| | - Hideyuki Tanabe
- Department of Evolutionary Studies of Biosystems School of Advanced Sciences SOKENDAI (The Graduate University for Advanced Studies) Hayama Japan
| | - Sayaka Hashima
- Department of Life Science Graduate School of Engineering Science Akita University Akita Japan
| | - Satoe Kasahara
- Faculty of Agriculture and Life Science Hirosaki University Hirosaki Japan
| | - Gen Morimoto
- Division of Avian Conservation Yamashina Institute for Ornithology Abiko City Japan.,Wildlife Conservation Center Department of Life Sciences Toho University Chiba Japan
| | - Osamu K Mikami
- Department of International and Regional Studies Faculty of Education Hokkaido University of Education Hakodate Japan
| | | | - Nobuyuki Kutsukake
- Department of Evolutionary Studies of Biosystems School of Advanced Sciences SOKENDAI (The Graduate University for Advanced Studies) Hayama Japan
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32
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Woelber BK, Hall CL, Howard DR. Environmental cues influence parental brood structure decisions in the burying beetle Nicrophorus marginatus. J ETHOL 2017. [DOI: 10.1007/s10164-017-0527-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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33
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Khwaja N, Hatchwell BJ, Freckleton RP, Green JP. Sex Allocation Patterns across Cooperatively Breeding Birds Do Not Support Predictions of the Repayment Hypothesis. Am Nat 2017; 190:547-556. [PMID: 28937820 DOI: 10.1086/693532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The repayment hypothesis predicts that reproductive females in cooperative breeding systems overproduce the helping sex. Thanks to well-documented examples of this predicted sex ratio bias, repayment has been considered an important driver of variation in sex allocation patterns. Here we test this hypothesis using data on population brood sex ratios and facultative sex allocation from 28 cooperatively breeding bird species. We find that biased sex ratios of helpers do not correlate with production biases in brood sex ratios, contrary to predictions. We also test whether females facultatively produce the helping sex in response to a deficiency of help (i.e., when they have fewer or no helpers). Although this is observed in a few species, it is not a significant trend overall, with a mean effect size close to zero. We conclude that, surprisingly, repayment does not appear to be a widespread influence on sex ratios in cooperatively breeding birds. We discuss possible explanations for our results and encourage further examination of the repayment model.
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34
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Sex-specific early survival drives adult sex ratio bias in snowy plovers and impacts mating system and population growth. Proc Natl Acad Sci U S A 2017. [PMID: 28634289 DOI: 10.1073/pnas.1620043114] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Adult sex ratio (ASR) is a central concept in population biology and a key factor in sexual selection, but why do most demographic models ignore sex biases? Vital rates often vary between the sexes and across life history, but their relative contributions to ASR variation remain poorly understood-an essential step to evaluate sex ratio theories in the wild and inform conservation. Here, we combine structured two-sex population models with individual-based mark-recapture data from an intensively monitored polygamous population of snowy plovers. We show that a strongly male-biased ASR (0.63) is primarily driven by sex-specific survival of juveniles rather than adults or dependent offspring. This finding provides empirical support for theories of unbiased sex allocation when sex differences in survival arise after the period of parental investment. Importantly, a conventional model ignoring sex biases significantly overestimated population viability. We suggest that sex-specific population models are essential to understand the population dynamics of sexual organisms: reproduction and population growth are most sensitive to perturbations in survival of the limiting sex. Overall, our study suggests that sex-biased early survival may contribute toward mating system evolution and population persistence, with implications for both sexual selection theory and biodiversity conservation.
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35
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Trouvé S, Jourdane J, Renaud F, Durand P, Morand S. ADAPTIVE SEX ALLOCATION IN A SIMULTANEOUS HERMAPHRODITE. Evolution 2017; 53:1599-1604. [DOI: 10.1111/j.1558-5646.1999.tb05423.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/1998] [Accepted: 05/06/1999] [Indexed: 11/30/2022]
Affiliation(s)
- Sandrine Trouvé
- Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Laboratoire de Biologie Animale; UMR 5555 du CNRS, Université de Perpignan; Av. de Villeneuve 66860 Perpignan Cedex France
| | - Joseph Jourdane
- Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Laboratoire de Biologie Animale; UMR 5555 du CNRS, Université de Perpignan; Av. de Villeneuve 66860 Perpignan Cedex France
| | - François Renaud
- Centre d'Etude sur le Polymorphisme des Micro-Organismes, CEPM/UMR CNRS-IRD 9926; Equipe: “Evolution des Systèmes Symbiotiques,” IRD; 911 Av. Agropolis, B.P. 5045 34032 Montpellier Cedex 1 France
| | - Patrick Durand
- Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Laboratoire de Biologie Animale; UMR 5555 du CNRS, Université de Perpignan; Av. de Villeneuve 66860 Perpignan Cedex France
| | - Serge Morand
- Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Laboratoire de Biologie Animale; UMR 5555 du CNRS, Université de Perpignan; Av. de Villeneuve 66860 Perpignan Cedex France
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36
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Reynolds RT, Lambert JS, Flather CH, White GC, Bird BJ, Baggett LS, Lambert C, Bayard De Volo S. Long-term demography of the Northern Goshawk in a variable environment. WILDLIFE MONOGRAPHS 2017. [DOI: 10.1002/wmon.1023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Richard T. Reynolds
- Rocky Mountain Research Station; 240 West Prospect Road Fort Collins CO 80526 USA
| | - Jeffrey S. Lambert
- Rocky Mountain Research Station; 240 West Prospect Road Fort Collins CO 80526 USA
| | - Curtis H. Flather
- Rocky Mountain Research Station; 240 West Prospect Road Fort Collins CO 80526 USA
| | - Gary C. White
- Department of Fisheries and Wildlife and Conservation Biology; Colorado State University; Fort Collins CO 80523 USA
| | - Benjamin J. Bird
- Rocky Mountain Research Station; 240 West Prospect Road Fort Collins CO 80526 USA
| | - L. Scott Baggett
- Rocky Mountain Research Station; 240 West Prospect Road Fort Collins CO 80526 USA
| | - Carrie Lambert
- Rocky Mountain Research Station; 240 West Prospect Road Fort Collins CO 80526 USA
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37
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Sato A, Karino K. Evidence for Strategic Sex Allocation in the Guppy ( Poecilia reticulata): Brood Sex Ratio and Size Predict Subsequent Adult Male Mating Success. Ethology 2017. [DOI: 10.1111/eth.12591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Aya Sato
- Faculty of Education; Gunma University; Maebashi Gunma Japan
| | - Kenji Karino
- Department of Biology; Tokyo Gakugei University; Koganei Tokyo Japan
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38
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Costanzo A, Panseri S, Giorgi A, Romano A, Caprioli M, Saino N. The Odour of Sex: Sex-Related Differences in Volatile Compound Composition among Barn Swallow Eggs Carrying Embryos of Either Sex. PLoS One 2016; 11:e0165055. [PMID: 27851741 PMCID: PMC5112806 DOI: 10.1371/journal.pone.0165055] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 10/05/2016] [Indexed: 11/18/2022] Open
Abstract
Avian communication has been traditionally believed to be mainly mediated by visual and auditory channels. However, an increasing number of studies are disclosing the role of olfaction in the interaction of birds with their social environment and with other species, as well as in other behaviors such as nest recognition, food location and navigation. Olfaction has also been suggested to play a role in parent-offspring communication not only in the post- but also in the pre-hatching period. Volatile compounds produced during embryogenesis and passively released through the eggshell pores may indeed represent the only cue at parents' disposal to assess offspring quality, including the sex composition of their clutch before hatching. In turn, sex identification before hatching may mediate adaptive strategies of allocation to either sex. In the present study, we analyzed odour composition of barn swallow eggs incubated in their nest in order to identify any sex-related differences in volatile compounds emitted. For the first time in any bird species, we also investigated whether odour composition is associated with relatedness. The evidence of differences in odour composition among eggs containing embryos of either sex indicates that parents have a cue to identify their brood sex composition even before hatching which can be used to modulate their behavior accordingly. Moreover, odour similarity within nests may represent the prerequisite for kin recognition in this species.
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Affiliation(s)
| | - Sara Panseri
- Department of Veterinary Science and Public Health, University of Milan, Milan, Italy
| | - Annamaria Giorgi
- Centre for Applied Studies in the Sustainable Management and Protection of the Mountain Environment, Ge.S.Di.Mont., University of Milan, Edolo, Brescia, Italy
| | - Andrea Romano
- Department of Biosciences, University of Milan, Milan, Italy
| | | | - Nicola Saino
- Department of Biosciences, University of Milan, Milan, Italy
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39
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Song Z, Lou Y, Hu Y, Deng Q, Gao W, Zhang K. Local resource competition affects sex allocation in a bird: experimental evidence. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.08.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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40
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Bouvier JC, Boivin T, Charmantier A, Lambrechts M, Lavigne C. More daughters in a less favourable world: Breeding in intensively-managed orchards affects tertiary sex-ratio in the great tit. Basic Appl Ecol 2016. [DOI: 10.1016/j.baae.2016.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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41
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42
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Turkia T, Selonen V, Brommer JE. Large-scale spatial synchrony in red squirrel ( Sciurus vulgaris) sex ratios. J Mammal 2016. [DOI: 10.1093/jmammal/gyw004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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43
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Sex allocation and secondary sex ratio in Cuban boa (Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters. Naturwissenschaften 2016; 103:48. [PMID: 27216175 DOI: 10.1007/s00114-016-1369-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/23/2016] [Accepted: 04/25/2016] [Indexed: 10/21/2022]
Abstract
Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (∼200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes.
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44
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No facultative manipulation of offspring sex ratio in relation to parental genetic characteristics in a bird with sex-specific heterozygosity-fitness correlation. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2119-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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45
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Romano A, Costanzo A, Caprioli M, Parolini M, Ambrosini R, Rubolini D, Saino N. Better-surviving barn swallow mothers produce more and better-surviving sons. Evolution 2016; 70:1120-8. [PMID: 26990898 DOI: 10.1111/evo.12908] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 03/04/2016] [Accepted: 03/08/2016] [Indexed: 11/28/2022]
Abstract
Sex allocation theory predicts that parents are selected to bias their progeny sex ratio (SR) toward the sex that will benefit the most from parental quality. Because parental quality may differentially affect survival of sons and daughters, a pivotal test of the adaptive value of SR adjustment is whether parents overproduce offspring of the sex that accrues larger fitness advantages from high parental quality. However, this crucial test of the long-term fitness consequences of sex allocation decisions has seldom been performed. In this study of the barn swallow (Hirundo rustica), we showed a positive correlation between the proportion of sons and maternal annual survival. We then experimentally demonstrated that this association did not depend on the differential costs of rearing offspring of either sex. Finally, we showed that maternal lifespan positively predicted lifespan of sons but not of daughters. Because in barn swallows lifespan is a strong determinant of lifetime reproductive success, the results suggest that mothers overproduce offspring of the sex that benefits the most from maternal quality. Hence, irrespective of mechanisms causing the SR bias and mother-son covariation in lifespan, we provide strong evidence that sex allocation decisions of mothers can highly impact on their lifetime fitness.
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Affiliation(s)
- Andrea Romano
- Department of Biosciences, University of Milan, I-20133, Milan, Italy.
| | | | - Manuela Caprioli
- Department of Biosciences, University of Milan, I-20133, Milan, Italy
| | - Marco Parolini
- Department of Biosciences, University of Milan, I-20133, Milan, Italy
| | - Roberto Ambrosini
- Department of Earth and Environmental Sciences (DISAT), University of Milano-Bicocca, I-20126, Milan, Italy
| | - Diego Rubolini
- Department of Biosciences, University of Milan, I-20133, Milan, Italy
| | - Nicola Saino
- Department of Biosciences, University of Milan, I-20133, Milan, Italy.
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46
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Are there physiological constraints on maternal ability to adjust sex ratios in mammals? J Zool (1987) 2016. [DOI: 10.1111/jzo.12327] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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47
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Schwanz LE, Robert KA. Costs of Rearing the Wrong Sex: Cross-Fostering to Manipulate Offspring Sex in Tammar Wallabies. PLoS One 2016; 11:e0146011. [PMID: 26849128 PMCID: PMC4743941 DOI: 10.1371/journal.pone.0146011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/12/2015] [Indexed: 11/19/2022] Open
Abstract
Sex allocation theory assumes that offspring sex (son vs. daughter) has consequences for maternal fitness. The most compelling experiment to test this theory would involve manipulating offspring sex and measuring the fitness consequences of having the "wrong" sex. Unfortunately, the logistical challenges of such an experiment limit its application. In tammar wallabies (Macropus eugenii), previous evidence suggests that mothers in good body condition are more likely to produce sons compared to mothers in poor condition, in support of the Trivers-Willard Hypothesis (TW) of condition-dependent sex allocation. More recently, we have found in our population of tammar wallabies that females with seemingly poor access to resources (based on condition loss over the dry summer) are more likely to produce sons, consistent with predictions from the Local Resource Competition (LRC) hypothesis, which proposes that production of sons or daughters is driven by the level of potential competition between mothers and philopatric daughters. We conducted a cross-fostering experiment in free-ranging tammar wallabies to disassociate the effects of rearing and birthing offspring of each sex. This allowed us to test the prediction of the LRC hypothesis that rearing daughters reduces the future direct fitness of mothers post-weaning and the prediction of the TW hypothesis that rearing sons requires more energy during lactation. Overall, we found limited costs to the mother of rearing the "wrong" sex, with switching of offspring sex only reducing the likelihood of a mother having a pouch young the following year. Thus, we found some support for both hypotheses in that rearing an unexpected son or an unexpected daughter both lead to reduced future maternal fitness. The study suggests that there may be context-specific costs associated with rearing the "wrong" sex.
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Affiliation(s)
- Lisa E. Schwanz
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD, Australia
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia
| | - Kylie A. Robert
- School of Animal Biology, The University of Western Australia, Perth, WA, Australia
- Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, VIC, Australia
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48
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Edwards AM, Cameron EZ, Pereira JC, Ferguson‐Smith MA. Paternal sex allocation: how variable is the sperm sex ratio? J Zool (1987) 2016. [DOI: 10.1111/jzo.12317] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. M. Edwards
- School of Biological Sciences University of Tasmania Hobart TAS Australia
- Department of Veterinary Medicine University of Cambridge Cambridge UK
| | - E. Z. Cameron
- School of Biological Sciences University of Tasmania Hobart TAS Australia
| | - J. C. Pereira
- Department of Veterinary Medicine University of Cambridge Cambridge UK
- Cytocell Ltd. Cambridge Technopark Cambridge UK
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49
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Ferrandiz-Rovira M, Freixas L, Torre I, Míguez S, Arrizabalaga A. Male-biased litter sex ratio in the southernmost Iberian population of edible dormouse: a strategy against isolation? ANIM BIOL 2016. [DOI: 10.1163/15707563-00002512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Litter sex ratio is a key component of parental fitness due to its impact on lifetime reproductive success. Multiple causes may lay at the origin of sex ratio variation among species and populations, such as maternal condition, local resource competition, presence of helpers, habitat quality or inbreeding levels. Whereas variation in sex allocation between species is relatively well understood, it is still unclear how and why litter sex allocation differs within species. Here, we present an analysis of litter sex ratio variation in two populations of edible dormice (Glis glis) over nine years of study. Populations are situated in the Montnegre and Montseny massifs in Catalonia (NE Iberian Peninsula). The Montnegre population is nowadays an isolated population located at the southernmost range edge of the species in the Iberian Peninsula. Litter sex ratio was male-biased in Montnegre but balanced in Montseny, whereas both populations showed a balanced adult sex ratio. We suggest that this differential sex allocation investment in Montnegre, may be a strategy to overcome isolation effects in this massif, as males are the dispersing sex in this and other rodent species.
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Affiliation(s)
- Mariona Ferrandiz-Rovira
- 1CREAF, Cerdanyola del Vallès 08193, Catalonia, Spain
- 2Univ Autònoma de Barcelona, Cerdanyola del Vallès 08193, Catalonia, Spain
| | - Lídia Freixas
- 3Museu de Ciències Naturals de Granollers, Granollers 08402, Catalonia, Spain
| | - Ignasi Torre
- 3Museu de Ciències Naturals de Granollers, Granollers 08402, Catalonia, Spain
| | - Sílvia Míguez
- 3Museu de Ciències Naturals de Granollers, Granollers 08402, Catalonia, Spain
| | - Antoni Arrizabalaga
- 3Museu de Ciències Naturals de Granollers, Granollers 08402, Catalonia, Spain
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50
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Koppmann-Rumpf B, Scherbaum-Heberer C, Schmidt KH. Influence of mortality and dispersal on sex ratio of the edible dormouse (Glis glis). FOLIA ZOOLOGICA 2015. [DOI: 10.25225/fozo.v64.i4.a4.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Bettina Koppmann-Rumpf
- Ecological Research Centre Schluechtern, Georg-Flemmig-Str. 5, 36381 Schluechtern, Germany
- J.W. Goethe University Frankfurt, Siesmayerstr. 70, 60323 Frankfurt am Main, Germany
| | | | - Karl-Heinz Schmidt
- Ecological Research Centre Schluechtern, Georg-Flemmig-Str. 5, 36381 Schluechtern, Germany
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