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Johannesson K, Faria R, Le Moan A, Rafajlović M, Westram AM, Butlin RK, Stankowski S. Diverse pathways to speciation revealed by marine snails. Trends Genet 2024; 40:337-351. [PMID: 38395682 DOI: 10.1016/j.tig.2024.01.002] [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: 09/30/2023] [Revised: 01/06/2024] [Accepted: 01/10/2024] [Indexed: 02/25/2024]
Abstract
Speciation is a key evolutionary process that is not yet fully understood. Combining population genomic and ecological data from multiple diverging pairs of marine snails (Littorina) supports the search for speciation mechanisms. Placing pairs on a one-dimensional speciation continuum, from undifferentiated populations to species, obscured the complexity of speciation. Adding multiple axes helped to describe either speciation routes or reproductive isolation in the snails. Divergent ecological selection repeatedly generated barriers between ecotypes, but appeared less important in completing speciation while genetic incompatibilities played a key role. Chromosomal inversions contributed to genomic barriers, but with variable impact. A multidimensional (hypercube) approach supported framing of questions and identification of knowledge gaps and can be useful to understand speciation in many other systems.
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Affiliation(s)
- Kerstin Johannesson
- Department of Marine Sciences, University of Gothenburg, Tjärnö Marine Laboratory, SE 45296 Strömstad, Sweden; The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden.
| | - Rui Faria
- The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden; CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal; BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661 Vairão, Portugal
| | - Alan Le Moan
- The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden; CNRS & Sorbonne Université, Station Biologique de Roscoff, Roscoff, France
| | - Marina Rafajlović
- The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden; Department of Marine Sciences, University of Gothenburg, SE 41390 Gothenburg, Sweden; Gothenburg Global Biodiversity Centre, University of Gothenburg, Gothenburg, Sweden
| | - Anja Marie Westram
- Department of Marine Sciences, University of Gothenburg, Tjärnö Marine Laboratory, SE 45296 Strömstad, Sweden; The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden; Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Roger K Butlin
- Department of Marine Sciences, University of Gothenburg, Tjärnö Marine Laboratory, SE 45296 Strömstad, Sweden; The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden; Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Sheffield, UK
| | - Sean Stankowski
- The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden; Institute of Science and Technology Austria, Klosterneuburg, Austria; Department of Ecology and Evolution, University of Sussex, Brighton, UK
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2
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Reeve J, Butlin RK, Koch EL, Stankowski S, Faria R. Chromosomal inversion polymorphisms are widespread across the species ranges of rough periwinkles (Littorina saxatilis and L. arcana). Mol Ecol 2023. [PMID: 37843465 DOI: 10.1111/mec.17160] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 09/13/2023] [Accepted: 09/20/2023] [Indexed: 10/17/2023]
Abstract
Inversions are thought to play a key role in adaptation and speciation, suppressing recombination between diverging populations. Genes influencing adaptive traits cluster in inversions, and changes in inversion frequencies are associated with environmental differences. However, in many organisms, it is unclear if inversions are geographically and taxonomically widespread. The intertidal snail, Littorina saxatilis, is one such example. Strong associations between putative polymorphic inversions and phenotypic differences have been demonstrated between two ecotypes of L. saxatilis in Sweden and inferred elsewhere, but no direct evidence for inversion polymorphism currently exists across the species range. Using whole genome data from 107 snails, most inversion polymorphisms were found to be widespread across the species range. The frequencies of some inversion arrangements were significantly different among ecotypes, suggesting a parallel adaptive role. Many inversions were also polymorphic in the sister species, L. arcana, hinting at an ancient origin.
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Affiliation(s)
- James Reeve
- Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, Sweden
| | - Roger K Butlin
- Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, Sweden
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield, UK
| | - Eva L Koch
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield, UK
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Sean Stankowski
- Institute of Science and Technology - Austria, Klosterneuburg, Austria
| | - Rui Faria
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield, UK
- Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
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3
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Montie S, Thomsen MS. Spatiotemporal stressors, not secondary structures or small temperature increases, control rapid facilitation of intertidal epifauna. MARINE ENVIRONMENTAL RESEARCH 2023; 187:105969. [PMID: 37003078 DOI: 10.1016/j.marenvres.2023.105969] [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: 01/31/2023] [Revised: 03/21/2023] [Accepted: 03/24/2023] [Indexed: 06/19/2023]
Abstract
Small animals (epifauna) are ubiquitous in marine systems. Epifauna have high secondary production and provide trophic linkages between primary producers and higher-order consumers, like fish. Despite their importance, little is known about how these animals respond to warming or how their communities vary across spatiotemporal gradients. Here we use mimics of turf seaweed and invasive kelp holdfast to test, in a 5-factorial field experiment, whether intertidal epifauna are facilitated by different habitat structures, temperature conditions, and along cooccurring spatiotemporal gradients. We found that facilitation of epifauna by intertidal turf seaweed peaked in summer, at low elevation, in older habitats and at a less wave-exposed site. However, epifauna were not affected by the presence of a secondary structure like kelp holdfast mimics or small temperature increases from passive solar heating of black and white mimics. There were many significant two-way, but few higher order interactions, showing stronger facilitation under specific environmental conditions, like at low elevation in summer, or low elevation in old habitats. These results highlight that turf-associated epifauna are controlled by vertical elevation, season, hydrodynamics, and habitat age, and appear to be resilient to small temperature increases. Findings are important to better understand linkages between primary producers and higher order consumers and system-wide productivity, and because fast growing turf, facilitated by global warming and eutrophication, are increasingly outcompeting slower growing large perennial canopy forming seaweeds, like kelp and rockweeds.
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Affiliation(s)
- Shinae Montie
- Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
| | - Mads S Thomsen
- Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand; Aarhus University, Department of Ecoscience, 4000, Roskilde, Denmark
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4
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Sil M, Roy A, Bhat HNP, Palden T, Karanth KP, Aravind NA. Role of paleoclimatic and paleohydrological processes in lineage divergence in freshwater organisms: A snippet from lentic genus Pila. Mol Phylogenet Evol 2023; 181:107723. [PMID: 36720420 DOI: 10.1016/j.ympev.2023.107723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 11/09/2022] [Accepted: 01/24/2023] [Indexed: 01/31/2023]
Abstract
The Indian subcontinent is extremely diverse in terms of its flora and fauna. However, only a handful of studies have aimed to understand the diversity of freshwater invertebrates using multiple lines of evidence in recent times. Here we aimed to estimate the cryptic diversity of two widespread freshwater snail species within the genus Pila (Röding, 1798) and uncover the processes behind lineage diversification in these species. We sequenced mitochondrial and nuclear markers from a comprehensive sampling of specimens from different river basins in India. We implemented an integrative taxonomy approach to delimit the lineages in these groups, employing phylogenetic, geometric morphometric and niche modelling-based methods. Then, we investigated the drivers of lineage divergence in these species using population genetic tools in conjunction with divergence time estimation. We found that both species consist of several genetically and ecologically distinct lineages. The genetic data showed that several of these lineages are restricted to a single or a few river basins. The divergence time estimation analyses indicated that the time frame of divergence within the species coincided with paleohydrological and paleoclimatic events in the Miocene. The diversification was primarily driven by allopatric isolation into different river basins. To conclude, the study sheds light on the complex interaction between the habitat preference of the species and the environment in shaping the diversification patterns in this group.
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Affiliation(s)
- Maitreya Sil
- Suri Sehgal Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, India; National Institute for Science Education and Research, Bhubaneswar 752050, India.
| | - Abhisikta Roy
- Suri Sehgal Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, India
| | - H N Poorna Bhat
- Suri Sehgal Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, India
| | - Tenzin Palden
- Centre for Ecological Sciences, Indian Institute of Science, Malleshwaram, Bangalore 560012, India
| | - K Praveen Karanth
- Centre for Ecological Sciences, Indian Institute of Science, Malleshwaram, Bangalore 560012, India
| | - N A Aravind
- Suri Sehgal Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, India; Yenepoya Research Centre, Yenepoya University, Derlakatte, Mangalore, India.
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5
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Panova MAZ, Varfolomeeva MA, Gafarova ER, Maltseva AL, Mikhailova NA, Granovitch AI. First insights into the gut microbiomes and the diet of the Littorina snail ecotypes, a recently emerged marine evolutionary model. Evol Appl 2023; 16:365-378. [PMID: 36793697 PMCID: PMC9923488 DOI: 10.1111/eva.13447] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 07/07/2022] [Indexed: 11/26/2022] Open
Abstract
Microbes can play a prominent role in the evolution of their hosts, facilitating adaptation to various environments and promoting ecological divergence. The Wave and Crab ecotypes of the intertidal snail Littorina saxatilis is an evolutionary model of rapid and repeated adaptation to environmental gradients. While patterns of genomic divergence of the Littorina ecotypes along the shore gradients have been extensively studied, their microbiomes have been so far overlooked. The aim of the present study is to start filling this gap by comparing gut microbiome composition of the Wave and Crab ecotypes using metabarcoding approach. Since Littorina snails are micro-grazers feeding on the intertidal biofilm, we also compare biofilm composition (i.e. typical snail diet) in the crab and wave habitats. In the results, we found that bacterial and eukaryotic biofilm composition varies between the typical habitats of the ecotypes. Further, the snail gut bacteriome was different from outer environments, being dominated by Gammaproteobacteria, Fusobacteria, Bacteroidia and Alphaproteobacteria. There were clear differences in the gut bacterial communities between the Crab and the Wave ecotypes as well as between the Wave ecotype snails from the low and high shores. These differences were both observed in the abundances and in the presence of different bacteria, as well as at different taxonomic level, from bacterial OTU's to families. Altogether, our first insights show that Littorina snails and their associated bacteria are a promising marine system to study co-evolution of the microbes and their hosts, which can help us to predict the future for wild species in the face of rapidly changing marine environments.
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Affiliation(s)
- Marina A. Z. Panova
- Department of Marine Sciences‐TjärnöUniversity of GothenburgGothenburgSweden
- The Centre for Marine Evolutionary Biology CeMEBUniversity of GothenburgGothenburgSweden
| | | | - Elizaveta R. Gafarova
- Department of Invertebrate ZoologySt. Petersburg State UniversitySt. PetersburgRussia
| | - Arina L. Maltseva
- Department of Invertebrate ZoologySt. Petersburg State UniversitySt. PetersburgRussia
| | - Natalia A. Mikhailova
- Department of Invertebrate ZoologySt. Petersburg State UniversitySt. PetersburgRussia
- Centre of Cell TechnologiesInstitute of Cytology RASSt. PetersburgRussia
| | - Andrei I. Granovitch
- Department of Invertebrate ZoologySt. Petersburg State UniversitySt. PetersburgRussia
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6
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Koch EL, Ravinet M, Westram AM, Johannesson K, Butlin RK. Genetic architecture of repeated phenotypic divergence in Littorina saxatilis ecotype evolution. Evolution 2022; 76:2332-2346. [PMID: 35994296 PMCID: PMC9826283 DOI: 10.1111/evo.14602] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 06/24/2022] [Accepted: 07/23/2022] [Indexed: 01/22/2023]
Abstract
Chromosomal inversions have been shown to play a major role in a local adaptation by suppressing recombination between alternative arrangements and maintaining beneficial allele combinations. However, so far, their importance relative to the remaining genome remains largely unknown. Understanding the genetic architecture of adaptation requires better estimates of how loci of different effect sizes contribute to phenotypic variation. Here, we used three Swedish islands where the marine snail Littorina saxatilis has repeatedly evolved into two distinct ecotypes along a habitat transition. We estimated the contribution of inversion polymorphisms to phenotypic divergence while controlling for polygenic effects in the remaining genome using a quantitative genetics framework. We confirmed the importance of inversions but showed that contributions of loci outside inversions are of similar magnitude, with variable proportions dependent on the trait and the population. Some inversions showed consistent effects across all sites, whereas others exhibited site-specific effects, indicating that the genomic basis for replicated phenotypic divergence is only partly shared. The contributions of sexual dimorphism as well as environmental factors to phenotypic variation were significant but minor compared to inversions and polygenic background. Overall, this integrated approach provides insight into the multiple mechanisms contributing to parallel phenotypic divergence.
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Affiliation(s)
- Eva L. Koch
- School of BiosciencesUniversity of SheffieldSheffieldUK,Department of ZoologyUniversity of CambridgeCambridgeUK
| | - Mark Ravinet
- School of Life SciencesUniversity of NottinghamNottinghamUK
| | - Anja M. Westram
- Institute of Science and Technology Austria (ISTA)KlosterneuburgAustria,Faculty of Biosciences and AquacultureNord UniversityBodøNorway
| | - Kerstin Johannesson
- Marine Science, Tjärnö Marine LaboratoryUniversity of GothenburgGothenburgSweden
| | - Roger K. Butlin
- School of BiosciencesUniversity of SheffieldSheffieldUK,Marine Science, Tjärnö Marine LaboratoryUniversity of GothenburgGothenburgSweden
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7
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White NJ, Beckerman AP, Snook RR, Brockhurst MA, Butlin RK, Eyres I. Experimental evolution of local adaptation under unidimensional and multidimensional selection. Curr Biol 2022; 32:1310-1318.e4. [DOI: 10.1016/j.cub.2022.01.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 11/25/2021] [Accepted: 01/18/2022] [Indexed: 01/17/2023]
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8
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Maltseva AL, Varfolomeeva MA, Ayanka RV, Gafarova ER, Repkin EA, Pavlova PA, Shavarda AL, Mikhailova NA, Granovitch AI. Linking ecology, morphology, and metabolism: Niche differentiation in sympatric populations of closely related species of the genus Littorina ( Neritrema). Ecol Evol 2021; 11:11134-11154. [PMID: 34429908 PMCID: PMC8366845 DOI: 10.1002/ece3.7901] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 05/08/2021] [Accepted: 06/22/2021] [Indexed: 12/03/2022] Open
Abstract
Divergence of ecological niches in phylogenetically closely related species indicates the importance of ecology in speciation, especially for sympatric species are considered. Such ecological diversification provides an advantage of alleviating interspecies competition and promotes more efficient exploitation of environmental resources, thus being a basis for ecological speciation. We analyzed a group of closely related species from the subgenus Neritrema (genus Littorina, Caenogastropoda) from the gravel-bouldery shores. In two distant sites at the Barents and Norwegian Sea, we examined the patterns of snail distribution during low tide (quantitative sampling stratified by intertidal level, presence of macrophytes, macrophyte species, and position on them), shell shape and its variability (geometric morphometrics), and metabolic characteristics (metabolomic profiling). The studied species diversified microbiotopes, which imply an important role of ecological specification in the recent evolution of this group. The only exception to this trend was the species pair L. arcana / L. saxatilis, which is specifically discussed. The ecological divergence was accompanied by differences in shell shape and metabolomic characteristics. Significant differences were found between L. obtusata versus L. fabalis and L. saxatilis / L. arcana versus L. compressa both in shell morphology and in metabolomes. L. saxatilis demonstrated a clear variability depending on intertidal level which corresponds to a shift in conditions within the occupied microhabitat. Interestingly, the differences between L. arcana (inhabiting the upper intertidal level) and L. compressa (inhabiting the lower one) were analogous to those between the upper and lower fractions of L. saxatilis. No significant level-dependent changes were found between the upper and lower fractions of L. obtusata, most probably due to habitat amelioration by fucoid macroalgae. All these results are discussed in the contexts of the role of ecology in speciation, ecological niche dynamics and conservatism, and evolutionary history of the Neritrema species.
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Affiliation(s)
- Arina L Maltseva
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
| | - Marina A Varfolomeeva
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
| | - Roman V Ayanka
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
| | - Elizaveta R Gafarova
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
| | - Egor A Repkin
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
| | - Polina A Pavlova
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
| | - Alexei L Shavarda
- Department of Analytical Phytochemistry Komarov Botanical Institute St. Petersburg Russia
- Research Park Centre for Molecular and Cell Technologies St. Petersburg State University St. Petersburg Russia
| | - Natalia A Mikhailova
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
- Centre of Cell Technologies Institute of Cytology Russian Academy of Sciences St. Petersburg Russia
| | - Andrei I Granovitch
- Department of Invertebrate Zoology St. Petersburg State University St. Petersburg Russia
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9
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Westram AM, Faria R, Johannesson K, Butlin R. Using replicate hybrid zones to understand the genomic basis of adaptive divergence. Mol Ecol 2021; 30:3797-3814. [PMID: 33638231 DOI: 10.1111/mec.15861] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 02/12/2021] [Indexed: 12/28/2022]
Abstract
Combining hybrid zone analysis with genomic data is a promising approach to understanding the genomic basis of adaptive divergence. It allows for the identification of genomic regions underlying barriers to gene flow. It also provides insights into spatial patterns of allele frequency change, informing about the interplay between environmental factors, dispersal and selection. However, when only a single hybrid zone is analysed, it is difficult to separate patterns generated by selection from those resulting from chance. Therefore, it is beneficial to look for repeatable patterns across replicate hybrid zones in the same system. We applied this approach to the marine snail Littorina saxatilis, which contains two ecotypes, adapted to wave-exposed rocks vs. high-predation boulder fields. The existence of numerous hybrid zones between ecotypes offered the opportunity to test for the repeatability of genomic architectures and spatial patterns of divergence. We sampled and phenotyped snails from seven replicate hybrid zones on the Swedish west coast and genotyped them for thousands of single nucleotide polymorphisms. Shell shape and size showed parallel clines across all zones. Many genomic regions showing steep clines and/or high differentiation were shared among hybrid zones, consistent with a common evolutionary history and extensive gene flow between zones, and supporting the importance of these regions for divergence. In particular, we found that several large putative inversions contribute to divergence in all locations. Additionally, we found evidence for consistent displacement of clines from the boulder-rock transition. Our results demonstrate patterns of spatial variation that would not be accessible without continuous spatial sampling, a large genomic data set and replicate hybrid zones.
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Affiliation(s)
- Anja M Westram
- IST Austria, Klosterneuburg, Austria.,Animal & Plant Sciences, Western Bank, University of Sheffield, Sheffield, UK.,Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Rui Faria
- Animal & Plant Sciences, Western Bank, University of Sheffield, Sheffield, UK.,CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal.,CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Porto, Portugal
| | - Kerstin Johannesson
- Marine Sciences, Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, Sweden
| | - Roger Butlin
- Animal & Plant Sciences, Western Bank, University of Sheffield, Sheffield, UK.,Marine Sciences, Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, Sweden
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10
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Koch EL, Morales HE, Larsson J, Westram AM, Faria R, Lemmon AR, Lemmon EM, Johannesson K, Butlin RK. Genetic variation for adaptive traits is associated with polymorphic inversions in Littorina saxatilis. Evol Lett 2021; 5:196-213. [PMID: 34136269 PMCID: PMC8190449 DOI: 10.1002/evl3.227] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 02/06/2021] [Accepted: 03/29/2021] [Indexed: 01/11/2023] Open
Abstract
Chromosomal inversions have long been recognized for their role in local adaptation. By suppressing recombination in heterozygous individuals, they can maintain coadapted gene complexes and protect them from homogenizing effects of gene flow. However, to fully understand their importance for local adaptation we need to know their influence on phenotypes under divergent selection. For this, the marine snail Littorina saxatilis provides an ideal study system. Divergent ecotypes adapted to wave action and crab predation occur in close proximity on intertidal shores with gene flow between them. Here, we used F2 individuals obtained from crosses between the ecotypes to test for associations between genomic regions and traits distinguishing the Crab‐/Wave‐adapted ecotypes including size, shape, shell thickness, and behavior. We show that most of these traits are influenced by two previously detected inversion regions that are divergent between ecotypes. We thus gain a better understanding of one important underlying mechanism responsible for the rapid and repeated formation of ecotypes: divergent selection acting on inversions. We also found that some inversions contributed to more than one trait suggesting that they may contain several loci involved in adaptation, consistent with the hypothesis that suppression of recombination within inversions facilitates differentiation in the presence of gene flow.
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Affiliation(s)
- Eva L Koch
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom
| | - Hernán E Morales
- Evolutionary Genetics Section Globe Institute University of Copenhagen Copenhagen Denmark.,Department of Marine Sciences University of Gothenburg Strömstad 45296 Sweden
| | - Jenny Larsson
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom
| | - Anja M Westram
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom.,IST Austria Klosterneuburg Austria
| | - Rui Faria
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom.,CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos Universidade do Porto Vairão Portugal
| | - Alan R Lemmon
- Department of Scientific Computing Florida State University Tallahassee Florida FL 32306-4120
| | - E Moriarty Lemmon
- Department of Biological Science Florida State University Tallahassee Florida FL 32306-4295
| | - Kerstin Johannesson
- Department of Marine Sciences University of Gothenburg Strömstad 45296 Sweden
| | - Roger K Butlin
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom.,Department of Marine Sciences University of Gothenburg Strömstad 45296 Sweden
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11
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Santos CA, Sonoda GG, Cortez T, Coutinho LL, Andrade SCS. Transcriptome Expression of Biomineralization Genes in Littoraria flava Gastropod in Brazilian Rocky Shore Reveals Evidence of Local Adaptation. Genome Biol Evol 2021; 13:6171147. [PMID: 33720344 PMCID: PMC8070887 DOI: 10.1093/gbe/evab050] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/09/2021] [Accepted: 03/11/2021] [Indexed: 12/11/2022] Open
Abstract
Understanding how selection shapes population differentiation and local adaptation in marine species remains one of the greatest challenges in the field of evolutionary biology. The selection of genes in response to environment-specific factors and microenvironmental variation often results in chaotic genetic patchiness, which is commonly observed in rocky shore organisms. To identify these genes, the expression profile of the marine gastropod Littoraria flava collected from four Southeast Brazilian locations in ten rocky shore sites was analyzed. In this first L. flava transcriptome, 250,641 unigenes were generated, and 24% returned hits after functional annotation. Independent paired comparisons between 1) transects, 2) sites within transects, and 3) sites from different transects were performed for differential expression, detecting 8,622 unique differentially expressed genes. Araçá (AR) and São João (SJ) transect comparisons showed the most divergent gene products. For local adaptation, fitness-related differentially expressed genes were chosen for selection tests. Nine and 24 genes under adaptative and purifying selection, respectively, were most related to biomineralization in AR and chaperones in SJ. The biomineralization-genes perlucin and gigasin-6 were positively selected exclusively in the site toward the open ocean in AR, with sequence variants leading to pronounced protein structure changes. Despite an intense gene flow among L. flava populations due to its planktonic larva, gene expression patterns within transects may be the result of selective pressures. Our findings represent the first step in understanding how microenvironmental genetic variation is maintained in rocky shore populations and the mechanisms underlying local adaptation in marine species.
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Affiliation(s)
- Camilla A Santos
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Gabriel G Sonoda
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Thainá Cortez
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Luiz L Coutinho
- Departamento de Ciência Animal, Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Universidade de São Paulo, Piracicaba, São Paulo, SP, Brazil
| | - Sónia C S Andrade
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
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12
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Smolinský R, Baláž V, Nürnberger B. Tadpoles of hybridising fire-bellied toads (B. bombina and B. variegata) differ in their susceptibility to predation. PLoS One 2020; 15:e0231804. [PMID: 33285552 PMCID: PMC7721483 DOI: 10.1371/journal.pone.0231804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 11/17/2020] [Indexed: 12/02/2022] Open
Abstract
The role of adaptive divergence in the formation of new species has been the subject of much recent debate. The most direct evidence comes from traits that can be shown to have diverged under natural selection and that now contribute to reproductive isolation. Here, we investigate differential adaptation of two fire-bellied toads (Anura, Bombinatoridae) to two types of aquatic habitat. Bombina bombina and B. variegata are two anciently diverged taxa that now reproduce in predator-rich ponds and ephemeral aquatic sites, respectively. Nevertheless, they hybridise extensively wherever their distribution ranges adjoin. We show in laboratory experiments that, as expected, B. variegata tadpoles are at relatively greater risk of predation from dragonfly larvae, even when they display a predator-induced phenotype. These tadpoles spent relatively more time swimming and so prompted more attacks from the visually hunting predators. We argue in the discussion that genomic regions linked to high activity in B. variegata should be barred from introgression into the B. bombina gene pool and thus contribute to gene flow barriers that keep the two taxa from merging into one.
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Affiliation(s)
- Radovan Smolinský
- Research Facility Studenec, Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
| | - Vojtech Baláž
- Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Beate Nürnberger
- Research Facility Studenec, Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
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13
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Galindo J, Carvalho J, Sotelo G, Duvetorp M, Costa D, Kemppainen P, Panova M, Kaliontzopoulou A, Johannesson K, Faria R. Genetic and morphological divergence between Littorina fabalis ecotypes in Northern Europe. J Evol Biol 2020; 34:97-113. [PMID: 32935387 DOI: 10.1111/jeb.13705] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 06/15/2020] [Accepted: 09/07/2020] [Indexed: 01/21/2023]
Abstract
Low dispersal marine intertidal species facing strong divergent selective pressures associated with steep environmental gradients have a great potential to inform us about local adaptation and reproductive isolation. Among these, gastropods of the genus Littorina offer a unique system to study parallel phenotypic divergence resulting from adaptation to different habitats related with wave exposure. In this study, we focused on two Littorina fabalis ecotypes from Northern European shores and compared patterns of habitat-related phenotypic and genetic divergence across three different geographic levels (local, regional and global). Geometric morphometric analyses revealed that individuals from habitats moderately exposed to waves usually present a larger shell size with a wider aperture than those from sheltered habitats. The phenotypic clustering of L. fabalis by habitat across most locations (mainly in terms of shell size) support an important role of ecology in morphological divergence. A genome scan based on amplified fragment length polymorphisms (AFLPs) revealed a heterogeneous pattern of differentiation across the genome between populations from the two different habitats, suggesting ecotype divergence in the presence of gene flow. The contrasting patterns of genetic structure between nonoutlier and outlier loci, and the decreased sharing of outlier loci with geographic distance among locations are compatible with parallel evolution of phenotypic divergence, with an important contribution of gene flow and/or ancestral variation. In the future, model-based inference studies based on sequence data across the entire genome will help unravelling these evolutionary hypotheses, improving our knowledge about adaptation and its influence on diversification within the marine realm.
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Affiliation(s)
- Juan Galindo
- Department of Biochemistry, Genetics and Immunology, Universidade de Vigo, Vigo, Spain.,Centro de Investigación Mariña (CIM-UVIGO), Vigo, Spain
| | - João Carvalho
- cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Portugal
| | - Graciela Sotelo
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Mårten Duvetorp
- Department of Marine Sciences -Tjärnö, University of Gothenburg, Strömstad, Sweden
| | - Diana Costa
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal.,CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal
| | - Petri Kemppainen
- Ecological Genetics Research Unit, Research Programme in Organismal and Evolutionary Biology, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Marina Panova
- Department of Marine Sciences -Tjärnö, University of Gothenburg, Strömstad, Sweden
| | - Antigoni Kaliontzopoulou
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal
| | - Kerstin Johannesson
- Department of Marine Sciences -Tjärnö, University of Gothenburg, Strömstad, Sweden
| | - Rui Faria
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.,CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal
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14
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Vasconcelos J, Sousa R, Tuset VM, Riera R. Island effect in the shell phenotypic plasticity of an intertidal gastropod. ZOOLOGY 2020; 141:125802. [PMID: 32574815 DOI: 10.1016/j.zool.2020.125802] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 04/21/2020] [Accepted: 05/06/2020] [Indexed: 11/28/2022]
Abstract
The pattern of shell shape variation in populations of the top shell, Phorcus sauciatus from Madeira Island (NE Atlantic) was analysed as a function of substrate type and wave exposure, using geometric morphometrics. We hypothesized that P. sauciatus shows morphological variations to inhabit contrasting environments. Highly significant differences in shell shape were found depending on both substrate type and coastal exposure. The most marked differences were found between exposed and sheltered environments. Rounded shells in exposed environments may be explained by physiological reasons, since larger muscles are needed to ensure attachment to substrate in areas subject to harsh conditions. On the other side, conically-shaped shells may accommodate a larger body but with a smaller foot, an adaptation to sheltered environments. Slight shape variations were also observed among substrates, mostly in the degree of differentiation of some whorls. Differences could be related to a particular use of habitat and/or to the degree of exposure to water current. These results suggest that P. sauciatus is locally adapted to varying coastal hydrodynamics and may be considered as a good model in studies on adaptations of fauna to certain climate change effects.
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Affiliation(s)
- J Vasconcelos
- Secretaria Regional de Educação, Avenida Zarco, Edifício do Governo Regional, 9004-528, Funchal, Madeira, Portugal; Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Casilla 297, Concepción, Chile; Centro de Ciências do Mar e do Ambiente (MARE), Quinta do Lorde Marina, Sítio da Piedade, 9200-044, Caniçal, Madeira, Portugal.
| | - R Sousa
- Direção de Serviços de Monitorização, Estudos e Investigação do Mar (DSEIMar), Direção Regional do Mar, Avenida do Mar e das Comunidades Madeirenses nº23, 1º andar, 9000-054, Funchal, Madeira, Portugal; Observatório Oceânico da Madeira, Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação (OOM/ARDITI) - Edifício Madeira Tecnopolo, 9020-105, Funchal, Madeira, Portugal.
| | - V M Tuset
- Department of Renewable Marine Resources, Institute of Marine Sciences (CSIC), Passeig Marítim 37-49, Barcelona 08003, Catalonia, Spain.
| | - R Riera
- Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Casilla 297, Concepción, Chile.
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15
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Perini S, Rafajlović M, Westram AM, Johannesson K, Butlin RK. Assortative mating, sexual selection, and their consequences for gene flow in Littorina. Evolution 2020; 74:1482-1497. [PMID: 32472616 DOI: 10.1111/evo.14027] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/07/2020] [Accepted: 05/21/2020] [Indexed: 01/01/2023]
Abstract
When divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple-effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail, Littorina saxatilis, occur in North Atlantic rocky-shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size-assortative mating has previously been documented. Here, we analyze the mating pattern in L. saxatilis with respect to size in intensively sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment.
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Affiliation(s)
- Samuel Perini
- Department of Marine Sciences, Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, 45296, Sweden
| | - Marina Rafajlović
- Department of Marine Sciences, University of Gothenburg, Gothenburg, 40530, Sweden
| | | | - Kerstin Johannesson
- Department of Marine Sciences, Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, 45296, Sweden
| | - Roger K Butlin
- Department of Marine Sciences, Tjärnö Marine Laboratory, University of Gothenburg, Strömstad, 45296, Sweden.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S102TN, United Kingdom
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16
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Larsson J, Westram AM, Bengmark S, Lundh T, Butlin RK. A developmentally descriptive method for quantifying shape in gastropod shells. J R Soc Interface 2020. [PMCID: PMC7061706 DOI: 10.1098/rsif.2019.0721] [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] [Indexed: 11/12/2022] Open
Abstract
The growth of snail shells can be described by simple mathematical rules. Variation in a few parameters can explain much of the diversity of shell shapes seen in nature. However, empirical studies of gastropod shell shape variation typically use geometric morphometric approaches, which do not capture this growth pattern. We have developed a way to infer a set of developmentally descriptive shape parameters based on three-dimensional logarithmic helicospiral growth and using landmarks from two-dimensional shell images as input. We demonstrate the utility of this approach, and compare it to the geometric morphometric approach, using a large set of Littorina saxatilis shells in which locally adapted populations differ in shape. Our method can be modified easily to make it applicable to a wide range of shell forms, which would allow for investigations of the similarities and differences between and within many different species of gastropods.
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Affiliation(s)
- J. Larsson
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | | | - S. Bengmark
- Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden
| | - T. Lundh
- Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden
| | - R. K. Butlin
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
- Department of Marine Sciences, University of Gothenburg, Stömstad, Sweden
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17
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Johannesson K, Zagrodzka Z, Faria R, Marie Westram A, Butlin RK. Is embryo abortion a post-zygotic barrier to gene flow between Littorina ecotypes? J Evol Biol 2019; 33:342-351. [PMID: 31724256 PMCID: PMC7079066 DOI: 10.1111/jeb.13570] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 11/07/2019] [Accepted: 11/12/2019] [Indexed: 11/25/2022]
Abstract
Genetic incompatibilities contribute to reproductive isolation between many diverging populations, but it is still unclear to what extent they play a role if divergence happens with gene flow. In contact zones between the "Crab" and "Wave" ecotypes of the snail Littorina saxatilis, divergent selection forms strong barriers to gene flow, while the role of post‐zygotic barriers due to selection against hybrids remains unclear. High embryo abortion rates in this species could indicate the presence of such barriers. Post‐zygotic barriers might include genetic incompatibilities (e.g. Dobzhansky–Muller incompatibilities) but also maladaptation, both expected to be most pronounced in contact zones. In addition, embryo abortion might reflect physiological stress on females and embryos independent of any genetic stress. We examined all embryos of >500 females sampled outside and inside contact zones of three populations in Sweden. Females' clutch size ranged from 0 to 1,011 embryos (mean 130 ± 123), and abortion rates varied between 0% and 100% (mean 12%). We described female genotypes by using a hybrid index based on hundreds of SNPs differentiated between ecotypes with which we characterized female genotypes. We also calculated female SNP heterozygosity and inversion karyotype. Clutch size did not vary with female hybrid index, and abortion rates were only weakly related to hybrid index in two sites but not at all in a third site. No additional variation in abortion rate was explained by female SNP heterozygosity, but increased female inversion heterozygosity added slightly to increased abortion. Our results show only weak and probably biologically insignificant post‐zygotic barriers contributing to ecotype divergence, and the high and variable abortion rates were marginally, if at all, explained by hybrid index of females.
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Affiliation(s)
- Kerstin Johannesson
- Department of Marine Sciences at Tjärnö, University of Gothenburg, Strömstad, Sweden
| | - Zuzanna Zagrodzka
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Rui Faria
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.,CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal
| | | | - Roger K Butlin
- Department of Marine Sciences at Tjärnö, University of Gothenburg, Strömstad, Sweden.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
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18
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Wong ELY, Nevado B, Osborne OG, Papadopulos AST, Bridle JR, Hiscock SJ, Filatov DA. Strong divergent selection at multiple loci in two closely related species of ragworts adapted to high and low elevations on Mount Etna. Mol Ecol 2019; 29:394-412. [PMID: 31793091 DOI: 10.1111/mec.15319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 11/28/2019] [Accepted: 11/28/2019] [Indexed: 12/20/2022]
Abstract
Recently diverged species present particularly informative systems for studying speciation and maintenance of genetic divergence in the face of gene flow. We investigated speciation in two closely related Senecio species, S. aethnensis and S. chrysanthemifolius, which grow at high and low elevations, respectively, on Mount Etna, Sicily and form a hybrid zone at intermediate elevations. We used a newly generated genome-wide single nucleotide polymorphism (SNP) dataset from 192 individuals collected over 18 localities along an elevational gradient to reconstruct the likely history of speciation, identify highly differentiated SNPs, and estimate the strength of divergent selection. We found that speciation in this system involved heterogeneous and bidirectional gene flow along the genome, and species experienced marked population size changes in the past. Furthermore, we identified highly-differentiated SNPs between the species, some of which are located in genes potentially involved in ecological differences between species (such as photosynthesis and UV response). We analysed the shape of these SNPs' allele frequency clines along the elevational gradient. These clines show significantly variable coincidence and concordance, indicative of the presence of multifarious selective forces. Selection against hybrids is estimated to be very strong (0.16-0.78) and one of the highest reported in literature. The combination of strong cumulative selection across the genome and previously identified intrinsic incompatibilities probably work together to maintain the genetic and phenotypic differentiation between these species - pointing to the importance of considering both intrinsic and extrinsic factors when studying divergence and speciation.
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Affiliation(s)
- Edgar L Y Wong
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Bruno Nevado
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Owen G Osborne
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | | | - Jon R Bridle
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Simon J Hiscock
- Department of Plant Sciences, University of Oxford, Oxford, UK
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19
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White NJ, Snook RR, Eyres I. The Past and Future of Experimental Speciation. Trends Ecol Evol 2019; 35:10-21. [PMID: 31522756 DOI: 10.1016/j.tree.2019.08.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/08/2019] [Accepted: 08/14/2019] [Indexed: 12/22/2022]
Abstract
Speciation is the result of evolutionary processes that generate barriers to gene flow between populations, facilitating reproductive isolation. Speciation is typically studied via theoretical models and snapshot tests in natural populations. Experimental speciation enables real-time direct tests of speciation theory and has been long touted as a critical complement to other approaches. We argue that, despite its promise to elucidate the evolution of reproductive isolation, experimental speciation has been underutilised and lags behind other contributions to speciation research. We review recent experiments and outline a framework for how experimental speciation can be implemented to address current outstanding questions that are otherwise challenging to answer. Greater uptake of this approach is necessary to rapidly advance understanding of speciation.
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Affiliation(s)
- Nathan J White
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Rhonda R Snook
- Department of Zoology, Stockholm University, Stockholm 106-91, Sweden
| | - Isobel Eyres
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
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20
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Ecomorphology of a generalist freshwater gastropod: complex relations of shell morphology, habitat, and fecundity. ORG DIVERS EVOL 2018. [DOI: 10.1007/s13127-018-0377-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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21
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Westram AM, Rafajlović M, Chaube P, Faria R, Larsson T, Panova M, Ravinet M, Blomberg A, Mehlig B, Johannesson K, Butlin R. Clines on the seashore: The genomic architecture underlying rapid divergence in the face of gene flow. Evol Lett 2018; 2:297-309. [PMID: 30283683 PMCID: PMC6121805 DOI: 10.1002/evl3.74] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 06/14/2018] [Accepted: 06/29/2018] [Indexed: 12/16/2022] Open
Abstract
Adaptive divergence and speciation may happen despite opposition by gene flow. Identifying the genomic basis underlying divergence with gene flow is a major task in evolutionary genomics. Most approaches (e.g., outlier scans) focus on genomic regions of high differentiation. However, not all genomic architectures potentially underlying divergence are expected to show extreme differentiation. Here, we develop an approach that combines hybrid zone analysis (i.e., focuses on spatial patterns of allele frequency change) with system-specific simulations to identify loci inconsistent with neutral evolution. We apply this to a genome-wide SNP set from an ideally suited study organism, the intertidal snail Littorina saxatilis, which shows primary divergence between ecotypes associated with different shore habitats. We detect many SNPs with clinal patterns, most of which are consistent with neutrality. Among non-neutral SNPs, most are located within three large putative inversions differentiating ecotypes. Many non-neutral SNPs show relatively low levels of differentiation. We discuss potential reasons for this pattern, including loose linkage to selected variants, polygenic adaptation and a component of balancing selection within populations (which may be expected for inversions). Our work is in line with theory predicting a role for inversions in divergence, and emphasizes that genomic regions contributing to divergence may not always be accessible with methods purely based on allele frequency differences. These conclusions call for approaches that take spatial patterns of allele frequency change into account in other systems.
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Affiliation(s)
- Anja M. Westram
- Department of Animal and Plant SciencesUniversity of SheffieldUK
- Current address: IST AustriaAm Campus 13400KlosterneuburgAustria
| | - Marina Rafajlović
- Department of Marine SciencesUniversity of Gothenburg40530GothenburgSweden
- Department of PhysicsUniversity of Gothenburg41296GothenburgSweden
| | - Pragya Chaube
- Department of Animal and Plant SciencesUniversity of SheffieldUK
| | - Rui Faria
- Department of Animal and Plant SciencesUniversity of SheffieldUK
| | - Tomas Larsson
- Department of Marine SciencesUniversity of Gothenburg40530GothenburgSweden
| | - Marina Panova
- Department of Marine Sciences ‐ TjärnöUniversity of Gothenburg45296StrömstadSweden
| | - Mark Ravinet
- CEES (Centre for Ecological and Evolutionary Synthesis)University of OsloOslo0316Norway
| | - Anders Blomberg
- Department of Chemistry and Molecular BiologyUniversity of Gothenburg40530GothenburgSweden
| | - Bernhard Mehlig
- Department of PhysicsUniversity of Gothenburg41296GothenburgSweden
| | - Kerstin Johannesson
- Department of Marine Sciences ‐ TjärnöUniversity of Gothenburg45296StrömstadSweden
| | - Roger Butlin
- Department of Animal and Plant SciencesUniversity of SheffieldUK
- Department of Marine Sciences ‐ TjärnöUniversity of Gothenburg45296StrömstadSweden
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22
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Ravinet M. Notes from a snail island: Littorinid evolution and adaptation. Mol Ecol 2018; 27:2781-2789. [PMID: 29802775 DOI: 10.1111/mec.14730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/01/2018] [Accepted: 05/06/2018] [Indexed: 12/20/2022]
Abstract
The most successful study systems are built on a foundation of decades of research on the basic biology, ecology and life history of the organisms in question. Combined with new technologies, this can provide a formidable means to address important issues in evolutionary biology and molecular ecology. Littorinid marine snails are a good example of this, with a rich literature on their taxonomy, speciation, thermal tolerance and behavioural adaptations. In August 2017, an international meeting on Littorinid evolution was held at the Tjärnö Marine Research Laboratory in Western Sweden. In this meeting review, I provide a summary of some of the exciting work on parallel evolution, sexual selection and adaptation to environmental stress presented there. I argue that newly available genomic resources present an opportunity for integrating the traditionally divergent fields of speciation and environmental adaptation in Littorinid research.
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Affiliation(s)
- Mark Ravinet
- Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
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23
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Johannesson K, Butlin RK, Panova M, Westram AM. Mechanisms of Adaptive Divergence and Speciation in Littorina saxatilis: Integrating Knowledge from Ecology and Genetics with New Data Emerging from Genomic Studies. POPULATION GENOMICS 2017. [DOI: 10.1007/13836_2017_6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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