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Schlicht E, Gilsenan C, Santema P, Türk A, Wittenzellner A, Kempenaers B. Removal of older males increases extra-pair siring success of yearling males. PLoS Biol 2024; 22:e3002584. [PMID: 38626215 PMCID: PMC11020368 DOI: 10.1371/journal.pbio.3002584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 03/11/2024] [Indexed: 04/18/2024] Open
Abstract
In animals, reproductive performance typically improves over time early in life. Several ultimate and proximate mechanisms may contribute to such an age-related improvement and these mechanisms can act in a relative or in an absolute sense. Low performance of young individuals may be the consequence of a comparison or competition with older individuals (relative), or it may be due to specific traits of young individuals and be unrelated to the presence of older competitors (absolute). Here, we perform a test to disentangle whether the effect of age class (yearling or older) on male extra-pair siring success is relative or absolute. Male age is the most consistent predictor of male extra-pair siring success across bird species, yet the mechanisms underlying this pattern are not well understood. Low extra-pair siring success of yearling males may be a consequence of the presence of older ("adult") males (hypothesis 1), because adult males are more successful in intra- and intersexual interactions or because females prefer to copulate with adult males when available (relative preference). Alternatively, low extra-pair siring success of yearlings may be independent of the presence of adult males (hypothesis 2), for example, if yearling males on average invest less in extra-pair behavior or if females avoid them as extra-pair mates, independent of the availability of older males (absolute preference). To distinguish between these 2 hypotheses, we experimentally manipulated the age structure of a nest-box-breeding population of blue tits (Cyanistes caeruleus) by removing almost all adult males, and compared patterns of extra-pair paternity in the experimental year with those from the preceding 15 "control" years. Removal of adult males resulted in a substantial increase in the extra-pair siring success of yearling males compared to the "control" years, but did not affect the population-level frequency of extra-pair paternity or its spatial patterns. Our results provide clear evidence that extra-pair siring success of yearlings can increase and that it depends on the presence of older males in the population, indicating a relative effect of age on reproductive performance. These results suggest that older males outcompete yearling males in direct or indirect interactions, in sperm competition or as a result of differences in attractiveness to females.
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Affiliation(s)
- Emmi Schlicht
- Max Planck Institute for Biological Intelligence, Department of Ornithology, Seewiesen, Germany
| | - Carol Gilsenan
- Max Planck Institute for Biological Intelligence, Department of Ornithology, Seewiesen, Germany
| | - Peter Santema
- Max Planck Institute for Biological Intelligence, Department of Ornithology, Seewiesen, Germany
- Edward Grey Institute, Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Agnes Türk
- Max Planck Institute for Biological Intelligence, Department of Ornithology, Seewiesen, Germany
| | - Andrea Wittenzellner
- Max Planck Institute for Biological Intelligence, Department of Ornithology, Seewiesen, Germany
| | - Bart Kempenaers
- Max Planck Institute for Biological Intelligence, Department of Ornithology, Seewiesen, Germany
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Sanghvi K, Vega-Trejo R, Nakagawa S, Gascoigne SJL, Johnson SL, Salguero-Gómez R, Pizzari T, Sepil I. Meta-analysis shows no consistent evidence for senescence in ejaculate traits across animals. Nat Commun 2024; 15:558. [PMID: 38228708 PMCID: PMC10791739 DOI: 10.1038/s41467-024-44768-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
Male reproductive traits such as ejaculate size and quality, are expected to decline with advancing age due to senescence. It is however unclear whether this expectation is upheld across taxa. We perform a meta-analysis on 379 studies, to quantify the effects of advancing male age on ejaculate traits across 157 species of non-human animals. Contrary to predictions, we find no consistent pattern of age-dependent changes in ejaculate traits. This result partly reflects methodological limitations, such as studies sampling a low proportion of adult lifespan, or the inability of meta-analytical approaches to document non-linear ageing trajectories of ejaculate traits; which could potentially lead to an underestimation of senescence. Yet, we find taxon-specific differences in patterns of ejaculate senescence. For instance, older males produce less motile and slower sperm in ray-finned fishes, but larger ejaculates in insects, compared to younger males. Notably, lab rodents show senescence in most ejaculate traits measured. Our study challenges the notion of universal reproductive senescence, highlighting the need for controlled methodologies and a more nuanced understanding of reproductive senescence, cognisant of taxon-specific biology, experimental design, selection pressures, and life-history.
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Affiliation(s)
- Krish Sanghvi
- Department of Biology, University of Oxford, Oxford, UK.
| | | | - Shinichi Nakagawa
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
| | | | - Sheri L Johnson
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | | | | | - Irem Sepil
- Department of Biology, University of Oxford, Oxford, UK.
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Schlicht E, Kempenaers B. Age trajectories in extra-pair siring success suggest an effect of maturation or early-life experience. J Evol Biol 2023; 36:1213-1225. [PMID: 37438929 DOI: 10.1111/jeb.14201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 05/22/2023] [Accepted: 06/11/2023] [Indexed: 07/14/2023]
Abstract
Across birds, male age is the most consistent predictor of extra-pair siring success, yet little is known about age effects on paternity over the lifetime of individuals. Here, we use data from a 13-year study of a population of blue tits (Cyanistes caeruleus) to investigate how extra-pair siring success changes with age within individuals. Our results indicate that extra-pair siring success does not continuously increase with male age. Instead, siring success was related to male age in a threshold fashion, whereby yearling males were less likely to gain paternity than older males. This effect was independent of the age of the social partner, but influenced by the age of the extra-pair female: success of yearlings at siring extra-pair young (EPY) with older females was even lower. Among males that sired at least one EPY, the number of extra-pair mates and the proportion of EPY sired were unrelated to male age. We found no evidence for an influence of selective disappearance on extra-pair reproduction. Senescence, if anything, only occurs at ages blue tits rarely reach. A literature review indicates that an effect of male age on extra-pair siring success may be limited to the switch from yearling to older in many species. Thus, the generally observed age effect on male extra-pair siring success may be linked to age class rather than continuous ageing. This suggests that lack of experience or not fully completed maturation are important drivers of age patterns in extra-pair paternity.
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Affiliation(s)
- Emmi Schlicht
- Department of Ornithology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
| | - Bart Kempenaers
- Department of Ornithology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
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Pereira PDC, Henrique EP, da Costa ER, Falcão ADJ, de Melo MAD, Schneider MPC, Burbano RMR, Diniz DG, Magalhães NGDM, Sherry DF, Diniz CWP, Guerreiro-Diniz C. Molecular Changes in the Brain of the Wintering Calidris pusilla in the Mangroves of the Amazon River Estuary. Int J Mol Sci 2023; 24:12712. [PMID: 37628893 PMCID: PMC10454129 DOI: 10.3390/ijms241612712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/30/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
Migrant birds prepare differently to fly north for breeding in the spring and for the flight to lower latitudes during autumn, avoiding the cold and food shortages of the Northern Hemisphere's harsh winter. The molecular events associated with these fundamental stages in the life history of migrants include the differential gene expression in different tissues. Semipalmated sandpipers (Calidris pusilla) are Arctic-breeding shorebirds that migrate to the coast of South America during the non-breeding season. In a previous study, we demonstrated that between the beginning and the end of the wintering period, substantial glial changes and neurogenesis occur in the brain of C. pusilla. These changes follow the epic journey of the autumn migration when a 5-day non-stop transatlantic flight towards the coast of South America and the subsequent preparation for the long-distance flight of the spring migration takes place. Here, we tested the hypothesis that the differential gene expressions observed in the brains of individuals captured in the autumn and spring windows are consistent with the previously described cellular changes. We searched for differential gene expressions in the brain of the semipalmated sandpiper, of recently arrived birds (RA) from the autumnal migration, and that of individuals in the premigratory period (PM) in the spring. All individuals were collected in the tropical coastal of northern Brazil in the mangrove region of the Amazon River estuary. We generated a de novo neurotranscriptome for C. pusilla individuals and compared the gene expressions across libraries. To that end, we mapped an RNA-Seq that reads to the C. pusilla neurotranscriptome in four brain samples of each group and found that the differential gene expressions in newly arrived and premigratory birds were related with neurogenesis, metabolic pathways (ketone body biosynthetic and the catabolic and lipid biosynthetic processes), and glial changes (astrocyte-dopaminergic neuron signaling, astrocyte differentiation, astrocyte cell migration, and astrocyte activation involved in immune response), as well as genes related to the immune response to virus infections (Type I Interferons), inflammatory cytokines (IL-6, IL-1β, TNF, and NF-κB), NLRP3 inflammasome, anti-inflammatory cytokines (IL-10), and cell death pathways (pyroptosis- and caspase-related changes).
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Affiliation(s)
- Patrick Douglas Corrêa Pereira
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
| | - Ediely Pereira Henrique
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
| | - Emanuel Ramos da Costa
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
| | - Anderson de Jesus Falcão
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
| | - Mauro André Damasceno de Melo
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
| | | | | | - Daniel Guerreiro Diniz
- Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil
- Laboratório de Microscopia Eletrônica, Seção de Hepatologia, Instituto Evandro Chagas, Belém 66093-020, PA, Brazil
| | - Nara Gyzely de Morais Magalhães
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
| | - David Francis Sherry
- Department of Psychology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6G 1G9, Canada
| | - Cristovam Wanderley Picanço Diniz
- Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil
| | - Cristovam Guerreiro-Diniz
- Laboratório de Biologia Molecular e Neuroecologia, Campus Bragança, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança 68600-000, PA, Brazil; (P.D.C.P.)
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Rekdal SL, Anmarkrud JA, Lifjeld JT, Johnsen A. Do female bluethroats without extra-pair offspring have more MHC-compatible social mates? Behav Ecol Sociobiol 2023. [DOI: 10.1007/s00265-023-03311-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Abstract
Abstract
Genes of the major histocompatibility complex (MHC) are crucial for adaptive immunity in jawed vertebrates, and theory predicts that there should be mate choice for optimizing MHC constitution in the offspring. In a previous study, we demonstrated a non-random female choice of extra-pair males in the bluethroat (Luscinia svecica), yielding offspring that was closer to an intermediate MHC class II (MHCII) allele count than their within-pair halfsiblings. The present study tests whether social pairs with only within-pair young (WPY) in their brood, in the same study population, had a combined MHC-constitution closer to a presumed intermediate optimum, than social pairs with extra-pair young (EPY), with a corresponding pattern in their offspring. As expected, we found that WPY from pure WPY-broods were more MHC-optimal than WPY from mixed broods, but only in broods of young (second year) males. Correspondingly, there was a tendency for social pairs with only WPY in their brood to be more MHC-compatible than social pairs with EPY in their brood, when the male was young. Older bluethroat males have considerably larger testes than young males, and their higher sperm competitiveness could help them secure paternity in their own brood, also when they are not MHC-compatible. In other words, in the sexual conflict over paternity, females may be more likely to realise their preference for a MHC-compatible mate when paired to a young male. As a possible fitness indicator, immune responsiveness to an injected antigen (PHA) was elevated for offspring closer to “the golden mean” in MHCII allele count.
Significance statement
This study contributes to our understanding of MHC-based mate choice in extra-pair mating systems, by showing that female bluethroats (Luscinia svecica) with an MHCII-compatible social mate tend to have no extra-pair young in their brood, but only when the social male is young. This elucidates a possible sexual conflict, in which older social males are able to override female preferences and prevent other males from gaining paternity in their brood through higher sperm production. Studying systems in which extra-pair paternity occurs offers an insight into the genetic benefits of mate choice, as extra-pair males, in contrast to social males, generally contribute only sperm. Further, the strict and thorough genotyping scheme applied in this study enabled us to demonstrate a preference for “the golden mean” in MHC-diversity in a species with one of the highest MHC class II-diversity known to date.
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Míčková K, Tomášek O, Jelínek V, Šulc M, Pazdera L, Albrechtová J, Albrecht T. Age-related changes in sperm traits and evidence for aging costs of sperm production in a sexually promiscuous passerine. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1105596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
In many animal species, organismal performance declines with age in a process known as aging or senescence. Senescence typically leads to a deterioration of physiological functionality and can impact the development of primary sexual phenotypes. Sperm production is a complex and costly process that is sensitive to changes in individual physiological state, yet remarkably little is known about age-related changes in sperm performance and aging costs of sperm production. Here we use a non-linear generalized additive mixed models (GAMM) modelling to evaluate age-related changes in postcopulatory sexual traits in the European barn swallow (Hirundo rustica rustica), a relatively short lived sexually promiscuous passerine species, where male extra-pair fertilization success has been shown to increase with age. We confirmed a positive relationship between sperm midpiece length and sperm velocity in this species. Within-male changes in sperm morphology and sperm velocity were in general absent, with only sperm length decreasing linearly with increasing age, although this change was negligible compared to the overall variation in sperm size among males. In contrast, the cloacal protuberance (CP) size changed nonlinearly with age, with an initial increase between the first and third year of life followed by a plateau. The results further indicate the existence of a trade-off between investments in sperm production and survival as males with large CP tended to have a reduced lifespan. This seems consistent with the idea of expensive sperm production and survival aging costs associated with investments in post-copulatory traits in this sexually promiscuous species.
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