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Faria FS, Areal M, Bitner-Mathé BC. Thermal Stress and Adult Fitness in a Drosophila suzukii Neotropical Propagule. NEOTROPICAL ENTOMOLOGY 2023; 52:993-1004. [PMID: 37702970 DOI: 10.1007/s13744-023-01075-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 07/24/2023] [Indexed: 09/14/2023]
Abstract
Drosophila suzukii (Matsumura 1931) is a cosmopolitan horticultural pest originally from temperate East Asia; yet, its recent introduction in southeast and central Brazil raises the possibility it might expand into warmer climatic zones. In theoretical terms, the adaptive potential of invasive species can be impaired by the lack of genetic variation, but, on the other hand, phenotypic plasticity might play an important role in the adaptation to the new environment. In this context, we investigated the effects of temperature variation (18°C, 22°C, and 28°C) on fitness traits and size of male reproductive organs (accessory glands and testis) in a natural D. suzukii population recently introduced in the neotropical region. Development time decreased significantly with increasing temperature, but egg-to-adult survival was not affected, attaining rates around 50% for the three temperatures. Development at 28°C affected differentially adult male and female biological performance: males displayed higher mortality and severe and permanent reduction in offspring production, whereas females showed the same mortality as controls and a temporary decrease in offspring production, followed of a clear recovery. Finally, reproductive organs size in immature and mature males was affected by developmental temperature variation in the following ways. Testis length decreased with body size (i.e., at higher temperatures) and increased with maturation time after adult hatching, whereas for accessory glands there was no significant difference between different temperatures, resulting in proportionally larger glands for smaller body sizes. These results show differences in developmental dynamics of reproductive tract structures due to temperature variation.
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Affiliation(s)
- Flavio Silva Faria
- Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mariana Areal
- Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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2
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Shanmugam D, Espinosa M, Gassen J, van Lamsweerde A, Pearson JT, Benhar E, Hill S. A multi-site study of the relationship between photoperiod and ovulation rate using Natural Cycles data. Sci Rep 2023; 13:8379. [PMID: 37225722 DOI: 10.1038/s41598-023-34940-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 05/10/2023] [Indexed: 05/26/2023] Open
Abstract
Many species exhibit seasonal patterns of breeding. Although humans can shield themselves from many season-related stressors, they appear to exhibit seasonal patterns of investment in reproductive function nonetheless, with levels of sex steroid hormones being highest during the spring and summer months. The current research builds on this work, examining the relationship between day length and ovarian function in two large samples of women using data from the Natural Cycles birth control application in each Sweden and the United States. We hypothesized that longer days would predict higher ovulation rates and sexual motivation. Results revealed that increasing day length duration predicts increased ovulation rate and sexual behavior, even while controlling for other relevant factors. Results suggest that day length may contribute to observed variance in women's ovarian function and sexual desire.
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Affiliation(s)
- Divya Shanmugam
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Matthew Espinosa
- Department of Psychology, Texas Christian University, 2955 S. University Dr., Fort Worth, TX, 76129, USA
| | - Jeffrey Gassen
- Department of Anthropology, Baylor University, 1214 S. 4Th St., Waco, TX, 76706, USA
| | | | | | | | - Sarah Hill
- Department of Psychology, Texas Christian University, 2955 S. University Dr., Fort Worth, TX, 76129, USA
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3
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Maciel EA, Guilherme FA. Species density per grid cell no longer predicts the local abundance of woody plants. ECOL INFORM 2022. [DOI: 10.1016/j.ecoinf.2022.101866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Jørgensen DB, Ørsted M, Kristensen TN. Sustained positive consequences of genetic rescue of fitness and behavioural traits in inbred populations of Drosophila melanogaster. J Evol Biol 2022; 35:868-878. [PMID: 35532930 PMCID: PMC9325394 DOI: 10.1111/jeb.14015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 04/10/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022]
Abstract
One solution to alleviate the detrimental genetic effects associated with reductions in population size and fragmentation is to introduce immigrants from other populations. While the effects of this genetic rescue on fitness traits are fairly well known, it is less clear to what extent inbreeding depression and subsequent genetic rescue affect behavioural traits. In this study, replicated crosses between inbred lines of Drosophila melanogaster were performed in order to investigate the effects of inbreeding and genetic rescue on egg-to-adult viability and negative geotaxis behaviour-a locomotor response used to measure, e.g. the effects of physiological ageing. Transgenerational effects of outcrossing were investigated by examining the fitness consequences in both the F1 and F4 generation. The majority of inbred lines showed evidence for inbreeding depression for both egg-to-adult viability and behavioural performance (95% and 66% of lines, respectively), with inbreeding depression being more pronounced for viability compared with the locomotor response. Subsequent outcrossing with immigrants led to an alleviation of the negative effects for both viability and geotaxis response resulting in inbred lines being similar to the outbred controls, with beneficial effects persisting from F1 to F4 . Overall, the results clearly show that genetic rescue can provide transgenerational rescue of small, inbred populations by rapidly improving population fitness components. Thus, we show that even the negative effects of inbreeding on behaviour, similar to that of neurodegeneration associated with physiological ageing, can be reversed by genetic rescue.
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Affiliation(s)
| | - Michael Ørsted
- Department of Chemistry and Bioscience, Aalborg University, Aalborg E, Denmark.,Department of Biology, Aarhus University, Aarhus C, Denmark
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5
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Stojanova B, Maurice S, Cheptou PO. Season-dependent effect of cleistogamy in Lamium amplexicaule: flower type origin versus inbreeding status. AMERICAN JOURNAL OF BOTANY 2020; 107:155-163. [PMID: 31889300 DOI: 10.1002/ajb2.1410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Inbreeding depression is traditionally considered a major factor favoring outcrossing in hermaphrodites. Recent experiments have shown that environmental conditions can influence the magnitude of inbreeding depression, but their relevance in natural populations is unclear. To investigate this, we studied the cleistogamous species Lamium amplexicaule, an annual species with individuals experiencing either spring or autumn environmental conditions. In this species, the proportion of cleistogamous/chasmogamous flowers changes according to seasonal cues (e.g., temperature, photoperiod). Our hypothesis was that the plasticity of cleistogamy is an adaptation to seasonal fitness variation in different flower progenies. METHODS To test this hypothesis, we produced the three possible types of progenies through controlled crosses: (1) selfed progeny from cleistogamous flowers; (2) chasmogamous selfed progeny; and (3) chasmogamous outcrossed progeny. Progeny fitness was then measured in a common garden in the two reproduction seasons (autumn and spring). RESULTS The results showed that season had a major impact on fitness. The fitness of the different progeny types changed across seasons, indicating that the effect of cleistogamy on progeny performance is season-dependent, consistent with a previous study in a similar environment. Surprisingly, the flower from which the progeny issued (cleistogamous or chasmogamous) had more impact on fitness than the inbred status of the progeny (selfed versus outcrossed), suggesting a potential role of epigenetic processes. CONCLUSIONS The observed patterns of variation were not consistent either with adaptation to environment-dependent inbreeding depression or to variation in resource availability, but were possibly consistent with adaptation to seasonal pollinator activity.
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Affiliation(s)
- Bojana Stojanova
- Department of Biology and Ecology & Institute of Environmental Technologies, Faculty of Science, University of Ostrava, Chittussiho 10, 71000, Ostrava, Czech Republic
- ISEM, Université de Montpellier, CNRS, IRD, Montpellier, France
- CEFE, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valery, Montpellier, EPHE - 1919 route de Mende, 34293, Montpellier cedex 05, France
| | | | - Pierre-Olivier Cheptou
- CEFE, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valery, Montpellier, EPHE - 1919 route de Mende, 34293, Montpellier cedex 05, France
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Zhao L, Li Y, Lou J, Yang Z, Liao H, Fu Q, Guo Z, Lian S, Hu X, Bao Z. Transcriptomic Profiling Provides Insights into Inbreeding Depression in Yesso Scallop Patinopecten yessoensis. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2019; 21:623-633. [PMID: 31300903 DOI: 10.1007/s10126-019-09907-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 05/30/2019] [Indexed: 06/10/2023]
Abstract
Inbreeding often causes a decline in biological fitness, known as inbreeding depression. In genetics study, inbreeding coefficient f gives the proportion by which the heterozygosity of an individual is reduced by inbreeding. With the development of high-throughput sequencing, researchers were able to perform deep approaches to investigate which genes are affected by inbreeding and reveal some molecular underpinnings of inbreeding depression. As one commercially important species, Yesso scallop Patinopecten yessoensis confront the same dilemma of inbreeding depression. To examine how inbreeding affects gene expression, we compared the transcriptome of two experimentally selfing families with inbreeding coefficient f reached 0.5 as well as one natural population (f ≈ 0) of P. yessoensis. A total of 24 RNA-Seq libraries were constructed using scallop adductor muscle, and eventually 676.56 M (96.85%) HQ reads were acquired. Based on differential gene analysis, we were able to identify nine common differentially expressed genes (DEGs) across the top-ranked 30 DEGs in both selfing families in comparation with the natural population. Remarkable, through weighted gene co-expression network analysis (WGCNA), five common DEGs were found enriched in the most significant inbreeding related functional module M14 (FDR = 1.64E-156), including SREBP1, G3BP2, SBK1, KIAA1161, and AATs-Glupro. These five genes showed significantly higher expression in self-bred progeny. Suggested by the genetic functional analysis, up-regulated SREBP1, G3BP2, and KIAA1161 may suggest a perturbing lipid metabolism, a severe inframammary reaction or immune response, and a stress-responsive behavior. Besides, the significant higher SBK1 and AATs-Glupro may reflect the abnormal cellular physiological situation. Together, these genetic aberrant transcriptomic performances may contribute to inbreeding depression in P. yessoensis, deteriorating the stress tolerance and survival phenotype in self-bred progeny. Our results would lay a foundation for further comprehensive understanding of bivalve inbreeding depression, which may potentially benefit the genetic breeding for scallop aquaculture.
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Affiliation(s)
- Liang Zhao
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
| | - Yangping Li
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Jiarun Lou
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Zhihui Yang
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Huan Liao
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Qiang Fu
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Zhenyi Guo
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
| | - Shanshan Lian
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China.
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
| | - Xiaoli Hu
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
| | - Zhenmin Bao
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), Ocean University of China, Qingdao, 266003, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
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7
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Leicht K, Jokela J, Seppälä O. Inbreeding does not alter the response to an experimental heat wave in a freshwater snail. PLoS One 2019; 14:e0220669. [PMID: 31393914 PMCID: PMC6687150 DOI: 10.1371/journal.pone.0220669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/19/2019] [Indexed: 11/18/2022] Open
Abstract
Global climate change affects natural populations of many species by increasing the average temperature and the frequency of extreme weather events (e.g. summer heat waves). The ability of organisms to cope with these environmental changes can, however, depend on their genetic properties. For instance, genetic load owing to inbreeding could alter organisms' responses to climate change-mediated environmental changes but such effects are often overlooked. We investigated the effects of an experimental heat wave (25°C versus 15°C) on life history (reproduction, size) and constitutive immune defence traits (phenoloxidase-like and antibacterial activity of haemolymph) in relation to inbreeding by manipulating the mating type (outcrossing, self-fertilization) in two populations of a hermaphroditic freshwater snail, Lymnaea stagnalis. High temperature increased reproduction and size of snails but impaired their immune function. In one of the two study populations, inbreeding reduced reproductive output of snails indicating inbreeding depression. Furthermore, this effect did not depend on the temperature snails were exposed to. Our results suggest that L. stagnalis snails can be negatively affected by inbreeding but it may not alter their responses to heat waves.
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Affiliation(s)
- Katja Leicht
- Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Jukka Jokela
- Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
| | - Otto Seppälä
- Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
- Research Department for Limnology, University of Innsbruck, Mondsee, Austria
- * E-mail:
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8
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Stewart KA, Draaijer R, Kolasa MR, Smallegange IM. The role of genetic diversity in the evolution and maintenance of environmentally-cued, male alternative reproductive tactics. BMC Evol Biol 2019; 19:58. [PMID: 30777004 PMCID: PMC6379956 DOI: 10.1186/s12862-019-1385-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/12/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alternative reproductive tactics (ARTs) are taxonomically pervasive strategies adopted by individuals to maximize reproductive success within populations. Even for conditionally-dependent traits, consensus postulates most ARTs involve both genetic and environmental interactions (GEIs), but to date, quantifying genetic variation underlying the threshold disposing an individual to switch phenotypes in response to an environmental cue has been a difficult undertaking. Our study aims to investigate the origins and maintenance of ARTs within environmentally disparate populations of the microscopic bulb mite, Rhizoglyphus robini, that express 'fighter' and 'scrambler' male morphs mediated by a complex combination of environmental and genetic factors. RESULTS Using never-before-published individual genetic profiling, we found all individuals across populations are highly inbred with the exception of scrambler males in stressed environments. In fact within the poor environment, scrambler males and females showed no significant difference in genetic differentiation (Fst) compared to all other comparisons, and although fighters were highly divergent from the rest of the population in both poor or rich environments (e.g., Fst, STRUCTURE), fighters demonstrated approximately three times less genetic divergence from the population in poor environments. AMOVA analyses further corroborated significant genetic differentiation across subpopulations, between morphs and sexes, and among subpopulations within each environment. CONCLUSION Our study provides new insights into the origin of ARTs in the bulb mite, highlighting the importance of GEIs: genetic correlations, epistatic interactions, and sex-specific inbreeding depression across environmental stressors. Asymmetric reproductive output, coupled with the purging of highly inbred individuals during environmental oscillations, also facilitates genetic variation within populations, despite evidence for strong directional selection. This cryptic genetic variation also conceivably facilitates stable population persistence even in the face of spatially or temporally unstable environmental challenges. Ultimately, understanding the genetic context that maintains thresholds, even for conditionally-dependent ARTs, will enhance our understanding of within population variation and our ability to predict responses to selection.
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Affiliation(s)
- K A Stewart
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands.
| | - R Draaijer
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands
| | - M R Kolasa
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17 St., 31-016, Krakow, Poland
| | - I M Smallegange
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands
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9
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Ali N. Digest: Stress and inbreeding depression in Drosophila melanogaster. Evolution 2018; 72:1727-1729. [PMID: 30024026 DOI: 10.1111/evo.13524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 06/12/2018] [Indexed: 11/30/2022]
Abstract
Do stressful conditions exacerbate inbreeding depression? Using Drosophila melanogaster, Schou et al. (2018) examine the mechanisms underlying the interaction between stress and inbreeding depression. The authors found that gene expression in inbred individuals was highly stochastic under benign conditions, but differential gene expression in inbred individuals was reduced compared to controls under stressful conditions.
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Affiliation(s)
- Nadya Ali
- Committee on Evolutionary Biology, University of Chicago (Doctoral student), Chicago, Illinois, 60637
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10
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Schou MF, Bechsgaard J, Muñoz J, Kristensen TN. Genome-wide regulatory deterioration impedes adaptive responses to stress in inbred populations of Drosophila melanogaster. Evolution 2018; 72:1614-1628. [PMID: 29738620 DOI: 10.1111/evo.13497] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 04/21/2018] [Accepted: 05/01/2018] [Indexed: 02/28/2024]
Abstract
Inbreeding depression is often intensified under environmental stress (i.e., inbreeding-stress interaction). Although the fitness consequences of this phenomenon are well-described, underlying mechanisms such as an increased expression of deleterious alleles under stress, or a lower capacity for adaptive responses to stress with inbreeding, have rarely been investigated. We investigated a fitness component (egg-to-adult viability) and gene-expression patterns using RNA-seq analyses in noninbred control lines and in inbred lines of Drosophila melanogaster exposed to benign temperature or heat stress. We find little support for an increase in the cumulative expression of deleterious alleles under stress. Instead, inbred individuals had a reduced ability to induce an adaptive gene regulatory stress response compared to controls. The decrease in egg-to-adult viability due to stress was most pronounced in the lines with the largest deviation in the adaptive stress response (R2 = 0.48). Thus, we find strong evidence for a lower capacity of inbred individuals to respond by gene regulation to stress and that this is the main driver of inbreeding-stress interactions. In comparison, the altered gene expression due to inbreeding at benign temperature showed no correlation with fitness and was pronounced in genomic regions experiencing the highest increase in homozygosity.
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Affiliation(s)
- Mads F Schou
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Jesper Bechsgaard
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Joaquin Muñoz
- Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg East, Denmark
| | - Torsten N Kristensen
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark
- Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg East, Denmark
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11
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Vega‐Trejo R, Head ML, Keogh JS, Jennions MD. Experimental evidence for sexual selection against inbred males. J Anim Ecol 2017; 86:394-404. [DOI: 10.1111/1365-2656.12615] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/24/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Regina Vega‐Trejo
- Division of Ecology and Evolution, Research School of Biology The Australian National University, Acton Canberra ACT 2601 Australia
| | - Megan L. Head
- Division of Ecology and Evolution, Research School of Biology The Australian National University, Acton Canberra ACT 2601 Australia
| | - J. Scott Keogh
- Division of Ecology and Evolution, Research School of Biology The Australian National University, Acton Canberra ACT 2601 Australia
| | - Michael D. Jennions
- Division of Ecology and Evolution, Research School of Biology The Australian National University, Acton Canberra ACT 2601 Australia
- Wissenschaftskolleg zu Berlin Wallotstraße 19 14193 Berlin Germany
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12
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Inbreeding depression by environment interactions in a free-living mammal population. Heredity (Edinb) 2016; 118:64-77. [PMID: 27876804 PMCID: PMC5176111 DOI: 10.1038/hdy.2016.100] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 08/06/2016] [Accepted: 08/12/2016] [Indexed: 12/12/2022] Open
Abstract
Experimental studies often find that inbreeding depression is more severe in harsh environments, but the few studies of in situ wild populations available to date rarely find strong support for this effect. We investigated evidence for inbreeding depression by environment interactions in nine traits in the individually monitored Soay sheep population of St Kilda, using genomic inbreeding coefficients based on 37 037 single-nucleotide polymorphism loci, and population density as an axis of environmental variation. All traits showed variation with population density and all traits showed some evidence for depression because of either an individual's own inbreeding or maternal inbreeding. However, only six traits showed evidence for an interaction in the expected direction, and only two interactions were statistically significant. We identify three possible reasons why wild population studies may generally fail to find strong support for interactions between inbreeding depression and environmental variation compared with experimental studies. First, for species with biparental inbreeding only, the amount of observed inbreeding in natural populations is generally low compared with that used in experimental studies. Second, it is possible that experimental studies sometimes actually impose higher levels of stress than organisms experience in the wild. Third, some purging of the deleterious recessive alleles that underpin interaction effects may occur in the wild.
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13
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Ebel ER, Phillips PC. Intrinsic differences between males and females determine sex-specific consequences of inbreeding. BMC Evol Biol 2016; 16:36. [PMID: 26860745 PMCID: PMC4748534 DOI: 10.1186/s12862-016-0604-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/28/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Inbreeding increases homozygosity and exposes deleterious recessive alleles, generally decreasing the fitness of inbred individuals. Interestingly, males and females are usually affected differently by inbreeding, though the more vulnerable sex depends on the species and trait measured. RESULTS We used the soil-dwelling nematode Caenorhabditis remanei to examine sex-specific inbreeding depression across nine lineages, five levels of inbreeding, and hundreds of thousands of progeny. Female nematodes consistently suffered greater fitness losses than their male counterparts, especially at high levels of inbreeding. CONCLUSIONS These results suggest that females experience stronger selection on genes contributing to reproductive traits. Inbreeding depression in males may be further reduced by sex chromosome hemizygosity, which affects the dominance of some mutations, as well as by the absence of sexual selection. Determining the relative contributions of sex-specific expression, genes on the sex chromosomes, and the environment they are filtered through-including opportunities for sexual selection-may explain the frequent though inconsistent records of sex differences in inbreeding depression, along with their implications for conservation and the evolution of mating systems.
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Affiliation(s)
- Emily R Ebel
- Institute of Ecology and Evolution and Department of Biology, 5289 University of Oregon, 97403, Eugene, Oregon, USA.,Present address: Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution and Department of Biology, 5289 University of Oregon, 97403, Eugene, Oregon, USA.
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14
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Enders LS, Nunney L. Reduction in the cumulative effect of stress-induced inbreeding depression due to intragenerational purging in Drosophila melanogaster. Heredity (Edinb) 2015; 116:304-13. [PMID: 26604190 DOI: 10.1038/hdy.2015.103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 11/09/2022] Open
Abstract
Environmental stress generally exacerbates the harmful effects of inbreeding and it has been proposed that this could be exploited in purging deleterious alleles from threatened inbred populations. However, understanding what factors contribute to variability in the strength of inbreeding depression (ID) observed across adverse environmental conditions remains a challenge. Here, we examined how the nature and timing of stress affects ID and the potential for purging using inbred and outbred Drosophila melanogaster larvae exposed to biotic (larval competition, bacteria infection) and abiotic (ethanol, heat) stressors compared with unstressed controls. ID was measured during (larval survival) and after (male mating success) stress exposure. The level of stress imposed by each stressor was approximately equal, averaging a 42% reduction in outbred larval survival relative to controls. All stressors induced on average the same ID, causing a threefold increase in lethal equivalents for larval survival relative to controls. However, stress-induced ID in larval success was followed by a 30% reduction in ID in mating success of surviving males. We propose that this fitness recovery is due to 'intragenerational purging' whereby fitness correlations facilitate stress-induced purging that increases the average fitness of survivors in later life history stages. For biotic stressors, post-stress reductions in ID are consistent with intragenerational purging, whereas for abiotic stressors, there appeared to be an interaction between purging and stress-induced physiological damage. For all stressors, there was no net effect of stress on lifetime ID compared with unstressed controls, undermining the prediction that stress enhances the effectiveness of population-level purging across generations.
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Affiliation(s)
- L S Enders
- Department of Biology, University of California, Riverside, Riverside, CA, USA.,Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - L Nunney
- Department of Biology, University of California, Riverside, Riverside, CA, USA
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Brock PM, Goodman SJ, Hall AJ, Cruz M, Acevedo-Whitehouse K. Context-dependent associations between heterozygosity and immune variation in a wild carnivore. BMC Evol Biol 2015; 15:242. [PMID: 26537228 PMCID: PMC4634738 DOI: 10.1186/s12862-015-0519-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 10/23/2015] [Indexed: 11/25/2022] Open
Abstract
Background A multitude of correlations between heterozygosity and fitness proxies associated with disease have been reported from wild populations, but the genetic basis of these associations is unresolved. We used a longitudinal dataset on wild Galapagos sea lions (Zalophus wollebaeki) to develop a relatively new perspective on this problem, by testing for associations between heterozygosity and immune variation across age classes and between ecological contexts. Results Homozygosity by locus was negatively correlated with serum immunoglobulin G production in pups (0–3 months of age), suggesting that reduced genetic diversity has a detrimental influence on the early development of immune defence in the Galapagos sea lion. In addition, homozygosity by locus was positively correlated with total circulating leukocyte concentration in juveniles (6–24 months of age), but only in a colony subject to the anthropogenic environmental impacts of development, pollution and introduced species, which suggests that reduced genetic diversity influences mature immune system activity in circumstances of high antigen exposure. Conclusions These findings demonstrate the environmental context-dependency of the phenotypic expression of immune variation, which is implicit in the theory of ecoimmunology, but which has been rarely demonstrated in the wild. They also indicate that heterozygosity may be linked to the maintenance of heterogeneity in mammalian immune system development and response to infection, adding to the body of evidence on the nature of the mechanistic link between heterozygosity and fitness. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0519-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Patrick M Brock
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK. .,Zoological Society of London, Regent's Park, London, NW1 4RY, UK. .,School of Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | | | - Ailsa J Hall
- Sea Mammal Research Unit, Scottish Ocean Institute, University of St. Andrews, Fife, KY16 8LB, UK.
| | - Marilyn Cruz
- Galapagos Genetics, Epidemiology and Pathology Laboratory, Galapagos National Park & University of Guayaquil, Puerto Ayora, Galapagos Islands, Ecuador.
| | - Karina Acevedo-Whitehouse
- Zoological Society of London, Regent's Park, London, NW1 4RY, UK. .,Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, Queretaro, 76230, Mexico.
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16
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Schou MF, Loeschcke V, Kristensen TN. Inbreeding depression across a nutritional stress continuum. Heredity (Edinb) 2015; 115:56-62. [PMID: 26059969 DOI: 10.1038/hdy.2015.16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/05/2015] [Indexed: 11/09/2022] Open
Abstract
Many natural populations experience inbreeding and genetic drift as a consequence of nonrandom mating or low population size. Furthermore, they face environmental challenges that may interact synergistically with deleterious consequences of increased homozygosity and further decrease fitness. Most studies on inbreeding-environment (I-E) interactions use one or two stress levels, whereby the resolution of the possible stress and inbreeding depression interaction is low. Here we produced Drosophila melanogaster replicate populations, maintained at three different population sizes (10, 50 and a control size of 500) for 25 generations. A nutritional stress gradient was imposed on the replicate populations by exposing them to 11 different concentrations of yeast in the developmental medium. We assessed the consequences of nutritional stress by scoring egg-to-adult viability and body mass of emerged flies. We found: (1) unequivocal evidence for I-E interactions in egg-to-adult viability and to a lesser extent in dry body mass, with inbreeding depression being more severe under higher levels of nutritional stress; (2) a steeper increase in inbreeding depression for replicate populations of size 10 with increasing nutritional stress than for replicate populations of size 50; (3) a nonlinear norm of reaction between inbreeding depression and nutritional stress; and (4) a faster increase in number of lethal equivalents in replicate populations of size 10 compared with replicate populations of size 50 with increasing nutritional stress levels. Our data provide novel and strong evidence that deleterious fitness consequences of I-E interactions are more pronounced at higher nutritional stress and at higher inbreeding levels.
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Affiliation(s)
- M F Schou
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - V Loeschcke
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - T N Kristensen
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
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17
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Kristensen TN, Hoffmann AA, Pertoldi C, Stronen AV. What can livestock breeders learn from conservation genetics and vice versa? Front Genet 2015; 6:38. [PMID: 25713584 PMCID: PMC4322732 DOI: 10.3389/fgene.2015.00038] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 01/26/2015] [Indexed: 11/17/2022] Open
Abstract
The management of livestock breeds and threatened natural population share common challenges, including small effective population sizes, high risk of inbreeding, and the potential benefits and costs associated with mixing disparate gene pools. Here, we consider what has been learnt about these issues, the ways in which the knowledge gained from one area might be applied to the other, and the potential of genomics to provide new insights. Although there are key differences stemming from the importance of artificial versus natural selection and the decreased level of environmental heterogeneity experienced by many livestock populations, we suspect that information from genetic rescue in natural populations could be usefully applied to livestock. This includes an increased emphasis on maintaining substantial population sizes at the expense of genetic uniqueness in ensuring future adaptability, and on emphasizing the way that environmental changes can influence the relative fitness of deleterious alleles and genotypes in small populations. We also suspect that information gained from cross-breeding and the maintenance of unique breeds will be increasingly important for the preservation of genetic variation in small natural populations. In particular, selected genes identified in domestic populations provide genetic markers for exploring adaptive evolution in threatened natural populations. Genomic technologies in the two disciplines will be important in the future in realizing genetic gains in livestock and maximizing adaptive capacity in wildlife, and particularly in understanding how parts of the genome may respond differently when exposed to population processes and selection.
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Affiliation(s)
- Torsten N. Kristensen
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg UniversityAalborg, Denmark
| | - Ary A. Hoffmann
- Department of Zoology and Department of Genetics, Bio21 Institute, The University of MelbourneMelbourne, VIC, Australia
| | - Cino Pertoldi
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg UniversityAalborg, Denmark
- Aalborg ZooAalborg, Denmark
| | - Astrid V. Stronen
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg UniversityAalborg, Denmark
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18
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Goodrich SH, Beans CM, Roach DA. Environmental conditions during early life determine the consequences of inbreeding in Agrostemma githago
(Caryophyllaceae). J Evol Biol 2013; 26:499-508. [DOI: 10.1111/jeb.12065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 10/25/2012] [Indexed: 12/01/2022]
Affiliation(s)
- S. H. Goodrich
- Department of Biology; University of Virginia; Charlottesville VA USA
| | - C. M. Beans
- Department of Biology; University of Virginia; Charlottesville VA USA
| | - D. A. Roach
- Department of Biology; University of Virginia; Charlottesville VA USA
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19
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Reed DH, Fox CW, Enders LS, Kristensen TN. Inbreeding-stress interactions: evolutionary and conservation consequences. Ann N Y Acad Sci 2012; 1256:33-48. [PMID: 22583046 DOI: 10.1111/j.1749-6632.2012.06548.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The effect of environmental stress on the magnitude of inbreeding depression has a long history of intensive study. Inbreeding-stress interactions are of great importance to the viability of populations of conservation concern and have numerous evolutionary ramifications. However, such interactions are controversial. Several meta-analyses over the last decade, combined with omic studies, have provided considerable insight into the generality of inbreeding-stress interactions, its physiological basis, and have provided the foundation for future studies. In this review, we examine the genetic and physiological mechanisms proposed to explain why inbreeding-stress interactions occur. We specifically examine whether the increase in inbreeding depression with increasing stress could be due to a concomitant increase in phenotypic variation, using a larger data set than any previous study. Phenotypic variation does usually increase with stress, and this increase can explain some of the inbreeding-stress interaction, but it cannot explain all of it. Overall, research suggests that inbreeding-stress interactions can occur via multiple independent channels, though the relative contribution of each of the mechanisms is unknown. To better understand the causes and consequences of inbreeding-stress interactions in natural populations, future research should focus on elucidating the genetic architecture of such interactions and quantifying naturally occurring levels of stress in the wild.
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Affiliation(s)
- David H Reed
- Department of Biology, University of Louisville, Louisville, Kentucky, USA
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