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Angst P, Haag CR, Ben-Ami F, Fields PD, Ebert D. Genome-Wide Allele Frequency Changes Reveal That Dynamic Metapopulations Evolve Differently. Mol Biol Evol 2024; 41:msae128. [PMID: 38935572 PMCID: PMC11229820 DOI: 10.1093/molbev/msae128] [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: 02/14/2024] [Revised: 06/14/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024] Open
Abstract
Two important characteristics of metapopulations are extinction-(re)colonization dynamics and gene flow between subpopulations. These processes can cause strong shifts in genome-wide allele frequencies that are generally not observed in "classical" (large, stable, and panmictic) populations. Subpopulations founded by one or a few individuals, the so-called propagule model, are initially expected to show intermediate allele frequencies at polymorphic sites until natural selection and genetic drift drive allele frequencies toward a mutation-selection-drift equilibrium characterized by a negative exponential-like distribution of the site frequency spectrum. We followed changes in site frequency spectrum distribution in a natural metapopulation of the cyclically parthenogenetic pond-dwelling microcrustacean Daphnia magna using biannual pool-seq samples collected over a 5-yr period from 118 ponds occupied by subpopulations of known age. As expected under the propagule model, site frequency spectra in newly founded subpopulations trended toward intermediate allele frequencies and shifted toward right-skewed distributions as the populations aged. Immigration and subsequent hybrid vigor altered this dynamic. We show that the analysis of site frequency spectrum dynamics is a powerful approach to understand evolution in metapopulations. It allowed us to disentangle evolutionary processes occurring in a natural metapopulation, where many subpopulations evolve in parallel. Thereby, stochastic processes like founder and immigration events lead to a pattern of subpopulation divergence, while genetic drift leads to converging site frequency spectrum distributions in the persisting subpopulations. The observed processes are well explained by the propagule model and highlight that metapopulations evolve differently from classical populations.
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Affiliation(s)
- Pascal Angst
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
| | - Christoph R Haag
- CEFE, Université de Montpellier, CNRS, EPHE, IRD, Montpellier 34293, France
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
| | - Frida Ben-Ami
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
- School of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
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Zhang X, Yang W, Blair D, Hu W, Yin M. RNA-seq analysis reveals changes in mRNA expression during development in Daphnia mitsukuri. BMC Genomics 2024; 25:302. [PMID: 38515024 PMCID: PMC10958850 DOI: 10.1186/s12864-024-10210-8] [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: 03/11/2024] [Indexed: 03/23/2024] Open
Abstract
Temporal transcriptional variation is a major contributor to functional evolution and the developmental process. Parthenogenetic water fleas of the genus Daphnia (Cladocera) provide an ideal model to characterize gene expression patterns across distinct developmental stages. Herein, we report RNA-seq data for female Daphnia mitsukuri at three developmental stages: the embryo, juvenile (three timepoints) and adult. Comparisons of gene expression patterns among these three developmental stages and weighted gene co-expression network analysis based on expression data across developmental stages identified sets of genes underpinning each of the developmental stages of D. mitsukuri. Specifically, highly expressed genes (HEGs) at the embryonic developmental stage were associated with cell proliferation, ensuring the necessary foundation for subsequent development; HEGs at the juvenile stages were associated with chemosensory perception, visual perception and neurotransmission, allowing individuals to enhance detection of potential environmental risks; HEGs at the adult stage were associated with antioxidative defensive systems, enabling adults to mount an efficient response to perceived environmental risks. Additionally, we found a significant overlap between expanded gene families of Daphnia species and HEGs at the juvenile stages, and these genes were associated with visual perception and neurotransmission. Our work provides a resource of developmental transcriptomes, and comparative analyses that characterize gene expression dynamics throughout development of Daphnia.
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Affiliation(s)
- Xiuping Zhang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Songhu Road 2005, Shanghai, China
| | - Wenwu Yang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Songhu Road 2005, Shanghai, China
| | - David Blair
- College of Marine and Environmental Sciences, James Cook University, Townsville Qld, 4811, Australia
| | - Wei Hu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Songhu Road 2005, Shanghai, China
| | - Mingbo Yin
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Songhu Road 2005, Shanghai, China.
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3
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Maruoka N, Makino T, Urabe J. RNA-seq analysis to identify genes related to resting egg production of panarctic Daphnia pulex. BMC Genomics 2023; 24:262. [PMID: 37198540 DOI: 10.1186/s12864-023-09369-3] [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: 02/17/2023] [Accepted: 05/08/2023] [Indexed: 05/19/2023] Open
Abstract
BACKGROUND The genus Daphnia switches its reproductive mode from subitaneous egg production to resting egg production in response to environmental stimuli. Although this life history trait is essential for surviving unsuitable environments, the molecular mechanism of resting egg production is little understood. In this study, we examined genes related to induction of resting egg production using two genotypes of panarctic Daphnia pulex, the JPN1 and JPN2 lineages, which differ genetically in the frequency of resting egg production. We reared these genotypes under high and low food levels. At the high food level, individuals of both genotypes continually produced subitaneous eggs, whereas at the low food level, only the JPN2 genotype produced resting eggs. Then, we performed RNA-seq analysis on specimens of three instars, including before and after egg production. RESULTS These results showed that expressed genes differed significantly between individuals grown under high and low food levels and among individuals of different instars and genotypes. Among these differentially expressed genes (DEGs), we found 16 that changed expression level before resting egg production. Some of these genes showed high-level expression only before resting egg production and one gene was an ortholog of bubblegum (bgm), which is reportedly up-regulated before diapause in bumblebees. According to gene ontology (GO) enrichment analysis, one GO term annotated as long-chain fatty acid biosynthetic process was enriched among these 16 genes. In addition, GO terms related to glycometabolism were enriched among down-regulated genes of individuals holding resting eggs, compared to those before resting egg production. CONCLUSIONS We found candidate genes highly expressed only before resting egg production. Although functions of candidate genes found in this study have not been reported previously in Daphnia, catabolism of long-chain fatty acids and metabolism of glycerates are related to diapause in other organisms. Thus, it is highly probable that candidate genes identified in this study are related to the molecular mechanism regulating resting egg production in Daphnia.
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Affiliation(s)
- Natsumi Maruoka
- Graduate School of Life sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, 022-795-6686, Miyagi, Japan.
- Center for Bioscience Research and Education, Utsunomiya University, 350 Mine-machi, Utsunomiya, 321-8505, 028-649-5129, Tochigi, Japan.
| | - Takashi Makino
- Graduate School of Life sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, 022-795-6686, Miyagi, Japan
| | - Jotaro Urabe
- Graduate School of Life sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, 022-795-6686, Miyagi, Japan
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4
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Ebert D. Daphnia as a versatile model system in ecology and evolution. EvoDevo 2022; 13:16. [PMID: 35941607 PMCID: PMC9360664 DOI: 10.1186/s13227-022-00199-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 06/20/2022] [Indexed: 11/10/2022] Open
Abstract
Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host–parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role.
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Affiliation(s)
- Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, CH-4051, Basel, Switzerland.
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5
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Cremer R, Wacker A, Schwarzenberger A. More Light Please: Daphnia Benefit From Light Pollution by Increased Tolerance Toward Cyanobacterial Chymotrypsin Inhibitors. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.834422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cryptochromes are evolutionary ancient blue-light photoreceptors that are part of the circadian clock in the nervous system of many organisms. Cryptochromes transfer information of the predominant light regime to the clock which results in the fast adjustment to photoperiod. Therefore, the clock is sensitive to light changes and can be affected by anthropogenic Artificial Light At Night (ALAN). This in turn has consequences for clock associated behavioral processes, e.g., diel vertical migration (DVM) of zooplankton. In freshwater ecosystems, the zooplankton genus Daphnia performs DVM in order to escape optically hunting predators and to avoid UV light. Concomitantly, Daphnia experience circadian changes in food-supply during DVM. Daphnia play the keystone role in the carbon-transfer to the next trophic level. Therefore, the whole ecosystem is affected during the occurrence of cyanobacteria blooms as cyanobacteria reduce food quality due to their production of digestive inhibitors (e.g., protease inhibitors). In other organisms, digestion is linked to the circadian clock. If this is also the case for Daphnia, the expression of protease genes should show a rhythmic expression following circadian expression of clock genes (e.g., cryptochrome 2). We tested this hypothesis and demonstrated that gene expression of the clock and of proteases was affected by ALAN. Contrary to our expectations, the activity of one type of proteases (chymotrypsins) was increased by ALAN. This indicates that higher protease activity might improve the diet utilization. Therefore, we treated D. magna with a chymotrypsin-inhibitor producing cyanobacterium and found that ALAN actually led to an increase in Daphnia’s growth rate in comparison to growth on the same cyanobacterium in control light conditions. We conclude that this increased tolerance to protease inhibitors putatively enables Daphnia populations to better control cyanobacterial blooms that produce chymotrypsin inhibitors in the Anthropocene, which is defined by light pollution and by an increase of cyanobacterial blooms due to eutrophication.
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Chin TA, Cristescu ME. Speciation in Daphnia. Mol Ecol 2021; 30:1398-1418. [PMID: 33522056 DOI: 10.1111/mec.15824] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/11/2021] [Accepted: 01/20/2021] [Indexed: 11/26/2022]
Abstract
The microcrustacean Daphnia is arguably one of the most studied zooplankton species, having a well understood ecology, life history, and a relatively well studied evolutionary history. Despite this wealth of knowledge, species boundaries within closely related species in this genus often remain elusive and the major evolutionary forces driving the diversity of daphniids remain controversial. This genus contains more than 80 species with multiple cryptic species complexes, with many closely related species able to hybridize. Here, we review speciation research in Daphnia within the framework of current speciation theory. We evaluate the role of geography, ecology, and biology in restricting gene flow and promoting diversification. Of the 253 speciation studies on Daphnia, the majority of studies examine geographic barriers (55%). While evidence shows that geographic barriers play a role in species divergence, ecological barriers are also probably prominent in Daphnia speciation. We assess the contribution of ecological and nonecological reproductive isolating barriers between closely related species of Daphnia and found that none of the reproductive isolating barriers are restricting gene flow completely. Research on reproductive isolating barriers has disproportionally focused on two species complexes, the Daphnia pulex and Daphnia longispina species complexes. Finally, we identify areas of research that remain relatively unexplored and discuss future research directions that build our understanding of speciation in daphniids.
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Affiliation(s)
- Tiffany A Chin
- Department of Biology, McGill University, Montreal, QC, Canada
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7
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The expression of circadian clock genes in Daphnia magna diapause. Sci Rep 2020; 10:19928. [PMID: 33199823 PMCID: PMC7669902 DOI: 10.1038/s41598-020-77065-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 10/30/2020] [Indexed: 11/17/2022] Open
Abstract
Diapause is a mechanism necessary for survival in arthropods. Often diapause induction and resurrection is light-dependent and therefore dependent on the photoperiod length and on the number of consecutive short-days. In many organisms, including the microcrustacean Daphnia magna, one functional entity with the capacity to measure seasonal changes in day-length is the circadian clock. There is a long-standing discussion that the circadian clock also controls photoperiod-induced diapause. We tested this hypothesis in D. magna, an organism which goes into a state of suspended animation with the shortening of the photoperiod. We measured gene expression of clock genes in diapause-destined embryos of D. magna in the initiation, resting and resurrection phases and checked it against gene expression levels of continuously developing embryos. We demonstrate that some genes of the clock are differentially expressed during diapause induction but not during its maintenance. Furthermore, the photoreceptor gene cry2 and the clock-associated gene brp are highly expressed during induction and early diapause, probably in order to produce excess mRNA to prepare for immediate resurrection. After resurrection, both types of embryos show a similar pattern of gene expression during development. Our study contributes significantly to the understanding of the molecular basis of diapause induction, maintenance and termination.
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8
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Baldwin-Brown JG, Long AD. Genomic Signatures of Local Adaptation in Clam Shrimp (Eulimnadia texana) from Natural Vernal Pools. Genome Biol Evol 2020; 12:1194-1206. [PMID: 32539143 PMCID: PMC7486962 DOI: 10.1093/gbe/evaa120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2020] [Indexed: 12/20/2022] Open
Abstract
Vernal pools are unique in their isolation and the strong selection acting on their resident species. Vernal pool clam shrimp (Eulimnadia texana) are a promising model due to ease of culturing, short generation time, small genomes, and obligate desiccated diapaused eggs. Clam shrimp are also androdioecious (sexes include males and hermaphrodites), and here we use population-scaled recombination rates to support the hypothesis that the heterogametic sex is recombination free in these shrimp. We collected short-read sequence data from pooled samples from different vernal pools to gain insights into local adaptation. We identify genomic regions in which some populations have allele frequencies that differ significantly from the metapopulation. BayPass (Gautier M. 2015. Genome-wide scan for adaptive divergence and association with population-specific covariates. Genetics 201(4):1555-1579.) detected 19 such genomic regions showing an excess of population subdivision. These regions on average are 550 bp in size and had 2.5 genes within 5 kb of them. Genes located near these regions are involved in Malpighian tubule function and osmoregulation, an essential function in vernal pools. It is likely that salinity profiles vary between pools and over time, and variants at these genes are adapted to local salinity conditions.
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Affiliation(s)
| | - Anthony D Long
- Department of Ecology and Evolutionary Biology, University of California Irvine
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9
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Czypionka T, Fields PD, Routtu J, van den Berg E, Ebert D, De Meester L. The genetic architecture underlying diapause termination in a planktonic crustacean. Mol Ecol 2019; 28:998-1008. [PMID: 30592346 DOI: 10.1111/mec.15001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 11/15/2018] [Accepted: 11/27/2018] [Indexed: 01/17/2023]
Abstract
Diapause is a feature of the life cycle of many invertebrates by which unfavourable environmental conditions can be outlived. The seasonal timing of diapause allows organisms to adapt to seasonal changes in habitat suitability and thus is key to their fitness. In the planktonic crustacean Daphnia, various cues can induce the production of diapause stages that are resistant to heat, drought or freezing and contain one to two embryos in developmental arrest. Daphnia is a keystone species of many freshwater ecosystems, where it acts as the main link between phytoplankton and higher trophic levels. The correct seasonal timing of diapause termination is essential to maintain trophic interactions and is achieved via a genetically based interpretation of environmental cues like photoperiod and temperature. Field monitoring and modelling studies raised concerns on whether populations can advance their seasonal release from diapause to advances in spring phenology under global change, or if a failure to adapt will cause trophic mismatches negatively affecting ecosystem functioning. Our capacity to understand and predict the evolution of diapause timing requires information about the genetic architecture underlying this trait. In this study, we identified eight quantitative trait loci (QTLs) and four epistatic interactions that together explained 66.5% of the variation in diapause termination in Daphnia magna using QTL mapping. Our results suggest that the most significant QTL is modulating diapause termination dependent on photoperiod and is involved in three of the four detected epistatic interactions. Candidate genes at this QTL could be identified through the integration with genome data and included the presynaptic active zone protein bruchpilot. Our findings contribute to understanding the genomic control of seasonal diapause timing in an ecological relevant species.
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Affiliation(s)
- Till Czypionka
- Laboratory of Aquatic Ecology and Evolutionary Biology, KU Leuven, Leuven, Belgium
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Jarkko Routtu
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland.,Molecular Ecology, Martin-Luther-Universität, Halle-Wittenberg, Germany
| | - Edwin van den Berg
- Laboratory of Aquatic Ecology and Evolutionary Biology, KU Leuven, Leuven, Belgium
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Luc De Meester
- Laboratory of Aquatic Ecology and Evolutionary Biology, KU Leuven, Leuven, Belgium
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10
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Seefeldt L, Ebert D. Temperature- versus precipitation-limitation shape local temperature tolerance in a Holarctic freshwater crustacean. Proc Biol Sci 2019; 286:20190929. [PMID: 31337313 PMCID: PMC6661336 DOI: 10.1098/rspb.2019.0929] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Species with wide geographical distributions are often adapted locally to the prevailing temperatures. To understand how they respond to ongoing climatic change, we must appreciate the interplay between temperature, seasonality and the organism's life cycle. The temperature experienced by many organisms results from an often-overlooked combination of climate and phenology. Summer-active (high latitude) populations are expected to adapt to local summer temperatures, but this is not expected for populations that outlive the summer in their dormant stage (low latitude, precipitation-limited). We recorded reproduction and survival in genotypes from 123 Holarctic populations of Daphnia magna during a multi-generation thermal ramp experiment. Genotypes from summer-active populations showed a positive relationship between heat tolerance and local summer temperature, whereas winter-active populations did not. These findings are consistent with the hypothesis that D. magna adapts to the local temperatures the animals experience during their planktonic phase. We conclude that predicting local temperature adaptation, in particular in the light of climate change, needs to consider the phenology of geographically wide-ranging species.
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Affiliation(s)
- Leonie Seefeldt
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
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11
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Toyota K, Cambronero Cuenca M, Dhandapani V, Suppa A, Rossi V, Colbourne JK, Orsini L. Transgenerational response to early spring warming in Daphnia. Sci Rep 2019; 9:4449. [PMID: 30872717 PMCID: PMC6418131 DOI: 10.1038/s41598-019-40946-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 02/27/2019] [Indexed: 01/30/2023] Open
Abstract
Temperature and photoperiod regulate key fitness traits in plants and animals. However, with temperature increase due to global warming, temperature cue thresholds are experienced at shorter photoperiods, disrupting the optimal seasonal timing of physiological, developmental and reproductive events in many species. Understanding the mechanisms of adaptation to the asynchrony between temperature and photoperiod is key to inform our understanding of how species will respond to global warming. Here, we studied the transgenerational mechanisms of responses of the cyclical parthenogen Daphnia magna to different photoperiod lengths co-occurring with warm temperature thereby assessing the impact of earlier spring warming on its fitness. Daphnia uses temperature and photoperiod cues to time dormancy, and to switch between sexual and asexual reproduction. Daphnia life cycle offers the opportunity to measure the relative contribution of plastic and genetic responses to environmental change across generations and over evolutionary time. We use transgenerational common garden experiments on three populations 'resurrected' from a biological archive experiencing temperature increase over five decades. Our results suggest that response to early spring warming evolved underpinned by a complex interaction between plastic and genetic mechanisms while a positive maternal contribution at matching environments between parental and offspring generation was also observed.
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Affiliation(s)
- Kenji Toyota
- Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
- Department of Biological Science, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa, 259-1293, Japan
- Department of Biological Science and Technology, Tokyo University of Science, Katsushika, Tokyo, Japan
| | - Maria Cambronero Cuenca
- Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
- Aquatic Ecology Department, EAWAG, Kastanienbaum, Switzerland
| | - Vignesh Dhandapani
- Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Antonio Suppa
- Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
- Department of Chemistry, Life Sciences and Environmental Sustainability University of Parma, Department of Life Sciences, Viale Usberti, 11/A, Parma, Italy
| | - Valeria Rossi
- Department of Chemistry, Life Sciences and Environmental Sustainability University of Parma, Department of Life Sciences, Viale Usberti, 11/A, Parma, Italy
| | - John K Colbourne
- Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Luisa Orsini
- Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
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12
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Genomic signatures of local adaptation to the degree of environmental predictability in rotifers. Sci Rep 2018; 8:16051. [PMID: 30375419 PMCID: PMC6207753 DOI: 10.1038/s41598-018-34188-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 09/27/2018] [Indexed: 11/09/2022] Open
Abstract
Environmental fluctuations are ubiquitous and thus essential for the study of adaptation. Despite this, genome evolution in response to environmental fluctuations —and more specifically to the degree of environmental predictability– is still unknown. Saline lakes in the Mediterranean region are remarkably diverse in their ecological conditions, which can lead to divergent local adaptation patterns in the inhabiting aquatic organisms. The facultatively sexual rotifer Brachionus plicatilis shows diverging local adaptation in its life-history traits in relation to estimated environmental predictability in its habitats. Here, we used an integrative approach —combining environmental, phenotypic and genomic data for the same populations– to understand the genomic basis of this diverging adaptation. Firstly, a novel draft genome for B. plicatilis was assembled. Then, genome-wide polymorphisms were studied using genotyping by sequencing on 270 clones from nine populations in eastern Spain. As a result, 4,543 high-quality SNPs were identified and genotyped. More than 90 SNPs were found to be putatively under selection with signatures of diversifying and balancing selection. Over 140 SNPs were correlated with environmental or phenotypic variables revealing signatures of local adaptation, including environmental predictability. Putative functions were associated to most of these SNPs, since they were located within annotated genes. Our results reveal associations between genomic variation and the degree of environmental predictability, providing genomic evidence of adaptation to local conditions in natural rotifer populations.
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13
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Bourgeois Y, Stritt C, Walser JC, Gordon SP, Vogel JP, Roulin AC. Genome-wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:438-451. [PMID: 30044522 DOI: 10.1111/tpj.14042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 06/20/2018] [Accepted: 07/17/2018] [Indexed: 06/08/2023]
Abstract
Grasses are essential plants for ecosystem functioning. Quantifying the selective pressures that act on natural variation in grass species is therefore essential regarding biodiversity maintenance. In this study, we investigate the selection pressures that act on two distinct populations of the grass model Brachypodium distachyon without prior knowledge about the traits under selection. We took advantage of whole-genome sequencing data produced for 44 natural accessions of B. distachyon and used complementary genome-wide selection scans (GWSS) methods to detect genomic regions under balancing and positive selection. We show that selection is shaping genetic diversity at multiple temporal and spatial scales in this species, and affects different genomic regions across the two populations. Gene ontology annotation of candidate genes reveals that pathogens may constitute important factors of positive and balancing selection in B. distachyon. We eventually cross-validated our results with quantitative trait locus data available for leaf-rust resistance in this species and demonstrate that, when paired with classical trait mapping, GWSS can help pinpointing candidate genes for further molecular validation. Thanks to a near base-perfect reference genome and the large collection of freely available natural accessions collected across its natural range, B. distachyon appears as a prime system for studies in ecology, population genomics and evolutionary biology.
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Affiliation(s)
- Yann Bourgeois
- New York University Abu Dhabi, PO Box 129188, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | - Christoph Stritt
- Institute of Plant and Microbial Biology, University of Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland
| | - Jean-Claude Walser
- Genetic Diversity Centre, ETH Zürich, Universitätstrasse 16, Zurich, Switzerland
| | - Sean P Gordon
- DOE Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - John P Vogel
- DOE Joint Genome Institute, Walnut Creek, CA, 94598, USA
| | - Anne C Roulin
- Institute of Plant and Microbial Biology, University of Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland
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14
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QTL mapping of a natural genetic polymorphism for long-term parasite persistence in Daphnia populations. Parasitology 2017; 144:1686-1694. [DOI: 10.1017/s0031182017001032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYKnowing the determinants of the geographic ranges of parasites is important for understanding their evolutionary ecology, epidemiology and their potential to expand their range. Here we explore the determinants of geographic range in the peculiar case of a parasite species – the microsporidian Hamiltosporidium tvaerminnensis – that has a limited geographic distribution in a wide-spread host – Daphnia magna. We conducted a quantitative trait loci (QTLs) analysis with monoclonal F2D. magna populations originating from a cross between a susceptible northern European genotype and a resistant central European genotype. Contrary to our expectations, long-term persistence turned out to be a quantitative trait across the F2 offspring. Evidence for two QTLs, one epistatic interaction and for further minor QTL was found. This finding contrasts markedly with the previously described bimodal pattern for long-term parasite persistence in natural host genotypes across Europe and leaves open the question of how a quantitative genetic trait could determine the disjunct geographic distribution of the parasite across Europe.
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Battelle BA. Opsins and Their Expression Patterns in the Xiphosuran Limulus polyphemus. THE BIOLOGICAL BULLETIN 2017; 233:3-20. [PMID: 29182506 DOI: 10.1086/693730] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The American horseshoe crab Limulus polyphemus (Linnaeus, 1758) is one of four extant species of xiphosuran chelicerates, the sister group to arachnids. Because of their position in the arthropod family tree and because they exhibit many plesiomorphic characteristics, Xiphosura are considered a proxy for the euchelicerate ancestor and therefore important for understanding the evolution and diversification of chelicerates and arthropods. Limulus polyphemus is the most extensively studied xiphosuran, and its visual system has long been a focus of studies critical for our understanding of basic mechanisms of vision and the evolution of visual systems in arthropods. Building upon a wealth of information about the anatomy and physiology of its visual system, advances in genetic approaches have greatly expanded possibilities for understanding its biochemistry. This review focuses on studies of opsin expression in L. polyphemus, which have been significantly advanced by the availability of transcriptomes and a recent high-quality assembly of its genome. These studies show that the repertoire of expressed opsins in L. polyphemus is far larger than anticipated, that the regulation of their expression in rhabdoms is far more complex than anticipated, and that photosensitivity may be distributed widely throughout the L. polyphemus central nervous system. The visual system of L. polyphemus is now arguably the best understood among chelicerates, and as such, it is a critical resource for furthering our understanding of the evolution and diversification of visual systems in arthropods.
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Key Words
- CNS, central nervous system
- LE, lateral eye
- LWS, long wavelength-sensitive
- LpArthOps, Limulus arthropsin
- LpCOps, Limulus C-type opsin
- LpOps, Limulus opsin
- LpPerOps, Limulus peropsin
- ME, median eye
- MWS, medium wavelength-sensitive
- Rh-LpOps, Limulus opsin in rhabdoms
- SWS, short wavelength-sensitive
- VE, ventral eye
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Bourgeois Y, Roulin AC, Müller K, Ebert D. Parasitism drives host genome evolution: Insights from thePasteuria ramosa-Daphnia magnasystem. Evolution 2017; 71:1106-1113. [DOI: 10.1111/evo.13209] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 02/16/2017] [Indexed: 01/14/2023]
Affiliation(s)
- Yann Bourgeois
- Zoological Institute; Basel University; Vesalgasse 1 4051 Basel Switzerland
| | - Anne C. Roulin
- Zoological Institute; Basel University; Vesalgasse 1 4051 Basel Switzerland
- Institute of Plant and Microbial Biology; Zollikerstrasse 107 8008 Zürich Switzerland
| | - Kristina Müller
- Zoological Institute; Basel University; Vesalgasse 1 4051 Basel Switzerland
| | - Dieter Ebert
- Zoological Institute; Basel University; Vesalgasse 1 4051 Basel Switzerland
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