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1.
Mitochondrion ; 76: 101884, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38626841

RESUMEN

Linguistic data from South Asia identified several language isolates in the subcontinent. The Vedda, an indigenous population of Sri Lanka, are the least studied amongst them. Therefore, to understand the initial peopling of Sri Lanka and the genetic affinity of the Vedda with other populations in Eurasia, we extensively studied the high-resolution autosomal and mitogenomes from the Vedda population of Sri Lanka. Our autosomal analyses suggest a close genetic link of Vedda with the tribal populations of India despite no evidence of close linguistic affinity, thus suggesting a deep genetic link of the Vedda with these populations. The mitogenomic analysis supports this association by pointing to an ancient link with Indian populations. We suggest that the Vedda population is a genetically drifted group with limited gene flow from neighbouring Sinhalese and Sri Lankan Tamil populations. Interestingly, the genetic ancestry sharing of Vedda neglects the isolation-by-distance model. Collectively, the demography of Sri Lanka is unique, where Sinhalese and Sri Lankan Tamil populations excessively admixed, whilst Vedda largely preserved their isolation and deep genetic association with India.


Asunto(s)
Genética de Población , Humanos , Sri Lanka , Flujo Génico , Genoma Mitocondrial , Lenguaje , India , Variación Genética , Sur de Asia
2.
Nature ; 628(8009): 811-817, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38632397

RESUMEN

Hybridization allows adaptations to be shared among lineages and may trigger the evolution of new species1,2. However, convincing examples of homoploid hybrid speciation remain rare because it is challenging to demonstrate that hybridization was crucial in generating reproductive isolation3. Here we combine population genomic analysis with quantitative trait locus mapping of species-specific traits to examine a case of hybrid speciation in Heliconius butterflies. We show that Heliconius elevatus is a hybrid species that is sympatric with both parents and has persisted as an independently evolving lineage for at least 180,000 years. This is despite pervasive and ongoing gene flow with one parent, Heliconius pardalinus, which homogenizes 99% of their genomes. The remaining 1% introgressed from the other parent, Heliconius melpomene, and is scattered widely across the H. elevatus genome in islands of divergence from H. pardalinus. These islands contain multiple traits that are under disruptive selection, including colour pattern, wing shape, host plant preference, sex pheromones and mate choice. Collectively, these traits place H. elevatus on its own adaptive peak and permit coexistence with both parents. Our results show that speciation was driven by introgression of ecological traits, and that speciation with gene flow is possible with a multilocus genetic architecture.


Asunto(s)
Mariposas Diurnas , Introgresión Genética , Especiación Genética , Hibridación Genética , Sitios de Carácter Cuantitativo , Animales , Femenino , Masculino , Mariposas Diurnas/anatomía & histología , Mariposas Diurnas/clasificación , Mariposas Diurnas/genética , Flujo Génico , Introgresión Genética/genética , Genoma de los Insectos/genética , Preferencia en el Apareamiento Animal , Fenotipo , Pigmentación/genética , Sitios de Carácter Cuantitativo/genética , Aislamiento Reproductivo , Selección Genética/genética , Especificidad de la Especie , Simpatría/genética , Alas de Animales/anatomía & histología , Alas de Animales/metabolismo
3.
Commun Biol ; 7(1): 468, 2024 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-38632370

RESUMEN

Bacterial species often comprise well-separated lineages, likely emerged and maintained by genetic isolation and/or ecological divergence. How these two evolutionary actors interact in the shaping of bacterial population structure is currently not fully understood. In this study, we investigate the genetic and ecological drivers underlying the evolution of Serratia marcescens, an opportunistic pathogen with high genomic flexibility and able to colonise diverse environments. Comparative genomic analyses reveal a population structure composed of five deeply-demarcated genetic clusters with open pan-genome but limited inter-cluster gene flow, partially explained by Restriction-Modification (R-M) systems incompatibility. Furthermore, a large-scale research on hundred-thousands metagenomic datasets reveals only a partial habitat separation of the clusters. Globally, two clusters only show a separate gene composition coherent with ecological adaptations. These results suggest that genetic isolation has preceded ecological adaptations in the shaping of the species diversity, an evolutionary scenario coherent with the Evolutionary Extended Synthesis.


Asunto(s)
Variación Genética , Serratia marcescens , Serratia marcescens/genética , Ecosistema , Flujo Génico , Genómica
4.
Mol Ecol ; 33(9): e17346, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38581173

RESUMEN

Wildlife populations are becoming increasingly fragmented by anthropogenic development. Small and isolated populations often face an elevated risk of extinction, in part due to inbreeding depression. Here, we examine the genomic consequences of urbanization in a caracal (Caracal caracal) population that has become isolated in the Cape Peninsula region of the City of Cape Town, South Africa, and is thought to number ~50 individuals. We document low levels of migration into the population over the past ~75 years, with an estimated rate of 1.3 effective migrants per generation. As a consequence of this isolation and small population size, levels of inbreeding are elevated in the contemporary Cape Peninsula population (mean FROH = 0.20). Inbreeding primarily manifests as long runs of homozygosity >10 Mb, consistent with the effects of isolation due to the rapid recent growth of Cape Town. To explore how reduced migration and elevated inbreeding may impact future population dynamics, we parameterized an eco-evolutionary simulation model. We find that if migration rates do not change in the future, the population is expected to decline, though with a low projected risk of extinction. However, if migration rates decline or anthropogenic mortality rates increase, the potential risk of extinction is greatly elevated. To avert a population decline, we suggest that translocating migrants into the Cape Peninsula to initiate a genetic rescue may be warranted in the near future. Our analysis highlights the utility of genomic datasets coupled with computational simulation models for investigating the influence of gene flow on population viability.


Asunto(s)
Flujo Génico , Genética de Población , Endogamia , Dinámica Poblacional , Animales , Sudáfrica , Densidad de Población , Urbanización , Migración Animal
5.
Mol Ecol ; 33(9): e17338, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38572696

RESUMEN

The maintenance of polymorphisms often depends on multiple selective forces, but less is known on the role of stochastic or historical processes in maintaining variation. The common wall lizard (Podarcis muralis) is a colour polymorphic species in which local colour morph frequencies are thought to be modulated by natural and sexual selection. Here, we used genome-wide single-nucleotide polymorphism data to investigate the relationships between morph composition and population biogeography at a regional scale, by comparing morph composition with patterns of genetic variation of 54 populations sampled across the Pyrenees. We found that genetic divergence was explained by geographic distance but not by environmental features. Differences in morph composition were associated with genetic and environmental differentiation, as well as differences in sex ratio. Thus, variation in colour morph frequencies could have arisen via historical events and/or differences in the permeability to gene flow, possibly shaped by the complex topography and environment. In agreement with this hypothesis, colour morph diversity was positively correlated with genetic diversity and rates of gene flow and inversely correlated with the likelihood of the occurrence of bottlenecks. Concurrently, we did not find conclusive evidence for selection in the two colour loci. As an illustration of these effects, we observed that populations with higher proportions of the rarer yellow and yellow-orange morphs had higher genetic diversity. Our results suggest that processes involving a decay in overall genetic diversity, such as reduced gene flow and/or bottleneck events have an important role in shaping population-specific morph composition via non-selective processes.


Asunto(s)
Flujo Génico , Genética de Población , Lagartos , Polimorfismo de Nucleótido Simple , Lagartos/genética , Lagartos/anatomía & histología , Lagartos/clasificación , Animales , Pigmentación/genética , Selección Genética , Variación Genética , Filogeografía , Masculino
6.
PLoS One ; 19(4): e0301577, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38635781

RESUMEN

The striped catfish Pseudoplatystoma magdaleniatum is a large-sized migratory species from the north Andes region, endemic to Magdalena basin and one of the major fishery resources. Despite the estimated reduction of over 80% of the fisheries production of this species throughout the basin in recent decades, its population in the lower Magdalena-Cauca basin showed healthy genetics after molecular analyses. However, the current conservation status of this species and several habitat disturbances demand the re-evaluation of its population genetics to infer evolutionary risks and assess potential changes. This work analyzed a total of 164 samples from the Cauca River collected downstream the Ituango Dam between 2019-2021 using species-specific microsatellite markers to compare the genetic diversity and structure in samples collected between 2010-2014 from the lower Magdalena-Cauca basin, previously analyzed. Our results showed a relatively stable panmictic population over time (4 to 10 years), with high genetic diversity and evidence of recent bottleneck. Promoting habitat connectivity to conserve gene flow, characterizing diversity and genetic structure over the entire basin, and integrating the results with future monitoring are important aspects for the management planning for P. magdaleniatum in the Magdalena-Cauca basin.


Asunto(s)
Bagres , Flujo Génico , Animales , Bagres/genética , Genética de Población , Repeticiones de Microsatélite/genética , Variación Genética
7.
Biosystems ; 239: 105199, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38641198

RESUMEN

Over the past quarter-century, the field of evolutionary biology has been transformed by the emergence of complete genome sequences and the conceptual framework known as the 'Net of Life.' This paradigm shift challenges traditional notions of evolution as a tree-like process, emphasizing the complex, interconnected network of gene flow that may blur the boundaries between distinct lineages. In this context, gene loss, rather than horizontal gene transfer, is the primary driver of gene content, with vertical inheritance playing a principal role. The 'Net of Life' not only impacts our understanding of genome evolution but also has profound implications for classification systems, the rapid appearance of new traits, and the spread of diseases. Here, we explore the core tenets of the 'Net of Life' and its implications for genome-scale phylogenetic divergence, providing a comprehensive framework for further investigations in evolutionary biology.


Asunto(s)
Evolución Molecular , Flujo Génico , Genoma , Filogenia , Genoma/genética , Animales , Humanos , Transferencia de Gen Horizontal , Modelos Genéticos , Evolución Biológica
8.
Curr Biol ; 34(9): 2020-2029.e6, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38614080

RESUMEN

Low genomic diversity is generally indicative of small population size and is considered detrimental by decreasing long-term adaptability.1,2,3,4,5,6 Moreover, small population size may promote gene flow with congeners and outbreeding depression.7,8,9,10,11,12,13 Here, we examine the connection between habitat availability, effective population size (Ne), and extinction by generating a 40× nuclear genome from the extinct blue antelope (Hippotragus leucophaeus). Historically endemic to the relatively small Cape Floristic Region in southernmost Africa,14,15 populations were thought to have expanded and contracted across glacial-interglacial cycles, tracking suitable habitat.16,17,18 However, we found long-term low Ne, unaffected by glacial cycles, suggesting persistence with low genomic diversity for many millennia prior to extinction in ∼AD 1800. A lack of inbreeding, alongside high levels of genetic purging, suggests adaptation to this long-term low Ne and that human impacts during the colonial era (e.g., hunting and landscape transformation), rather than longer-term ecological processes, were central to its extinction. Phylogenomic analyses uncovered gene flow between roan (H. equinus) and blue antelope, as well as between roan and sable antelope (H. niger), approximately at the time of divergence of blue and sable antelope (∼1.9 Ma). Finally, we identified the LYST and ASIP genes as candidates for the eponymous bluish pelt color of the blue antelope. Our results revise numerous aspects of our understanding of the interplay between genomic diversity and evolutionary history and provide the resources for uncovering the genetic basis of this extinct species' unique traits.


Asunto(s)
Antílopes , Extinción Biológica , Densidad de Población , Animales , Antílopes/genética , Antílopes/fisiología , Variación Genética , Flujo Génico , Adaptación Fisiológica/genética , Ecosistema , Genoma
9.
Anim Genet ; 55(3): 410-419, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38584302

RESUMEN

The Baise horse, an indigenous horse breed mainly distributed in the Baise region of Guangxi province in southwest China, has a long history as draft animal. However, there is a lack of research regarding the origin and ancestral composition of the Baise horse. In this study, whole-genome resequencing data from 236 horses of seven Chinese indigenous horse breeds, five foreign horse breeds, and four Przewalski's horses were used to investigate the relationships between the Baise horse and other horse breeds. The results showed that foreign horse breeds had no significant impact on the formation of the Baise horse. The two southwestern horse populations, the Debao pony and the Jinjiang horse, exhibit the closest genetic affinity with the Baise horse. This is consistent with their adjacent geographical distribution. Analysis of the migration route revealed a gene flow from the Chakouyi horse into the Baise horse. In summary, our results confirm that the formation of the Baise horse did not involve participation from foreign breeds. Geographical distance emerges as a crucial factor in determining the genetic relationships with the Baise horse. Gene flows of indigenous horse breeds along ancient routes of trade activities had played a role in the formation of the Baise horse.


Asunto(s)
Secuenciación Completa del Genoma , Animales , Caballos/genética , Secuenciación Completa del Genoma/veterinaria , China , Cruzamiento , Flujo Génico , Genoma
10.
J Hered ; 115(3): 277-291, 2024 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-38501510

RESUMEN

The Zagros Mountains, characterized by complex topography and three large drainage systems, harbor the endemic freshwater crab Potamon persicum in Iran. Our study delves into the evolutionary history of P. persicum, utilizing two mitochondrial and one nuclear marker. We collected 214 specimens from 24 localities, identifying 21 haplotypes grouped into two major evolutionary lineages. Substantial differentiation exists between drainage systems and lineages. Historical demographic analysis revealed a significant decrease in population size during the late Holocene, accompanied by a recent population bottleneck. Species distribution modeling has revealed eastward shifts in suitable habitats between the last glacial maximum and the present day. Following the last glacial maximum, habitat fragmentation occurred, resulting in the establishment of small populations. These smaller populations are more vulnerable to climatic and geological events, thereby limiting gene flow and accelerating genetic differentiation within species. Historical biogeographic analysis traced the origin of P. persicum to the western Zagros Mountains, with major genetic divergence occurring during the Pleistocene. Our genetic analyses suggest that P. persicum may have shown a genetic pattern similar to a classical ring species before the Pleistocene. The Namak Lake sub-basin could have served as a contact zone where populations did not interbreed but were connected through gene flow in a geographic ring. Currently, genetic separation is evident between basins, indicating that P. persicum in the Zagros Mountains is not a contemporary ring species. Also, our biogeographical analysis estimated that range evolution may have been driven initially by dispersal, and only during the late Pleistocene by vicariance.


Asunto(s)
ADN Mitocondrial , Flujo Génico , Variación Genética , Genética de Población , Haplotipos , Filogeografía , Animales , ADN Mitocondrial/genética , Filogenia , Irán , Ecosistema , Agua Dulce , Braquiuros/genética , Braquiuros/clasificación , Densidad de Población , Análisis de Secuencia de ADN , Teorema de Bayes
11.
Ann Bot ; 133(7): 917-930, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38441303

RESUMEN

BACKGROUND AND AIMS: Plant breeders are increasingly turning to crop wild relatives (CWRs) to ensure food security in a rapidly changing environment. However, CWR populations are confronted with various human-induced threats, including hybridization with their nearby cultivated crops. This might be a particular problem for wild coffee species, which often occur near coffee cultivation areas. Here, we briefly review the evidence for wild Coffea arabica (cultivated as Arabica coffee) and Coffea canephora (cultivated as Robusta coffee) and then focused on C. canephora in the Yangambi region in the Democratic Republic of the Congo. There, we examined the geographical distribution of cultivated C. canephora and the incidence of hybridization between cultivated and wild individuals within the rainforest. METHODS: We collected 71 C. canephora individuals from home gardens and 12 C. canephora individuals from the tropical rainforest in the Yangambi region and genotyped them using genotyping-by-sequencing (GBS). We compared the fingerprints with existing GBS data from 388 C. canephora individuals from natural tropical rainforests and the INERA Coffee Collection, a Robusta coffee field gene bank and the most probable source of cultivated genotypes in the area. We then established robust diagnostic fingerprints that genetically differentiate cultivated from wild coffee, identified cultivated-wild hybrids and mapped their geographical position in the rainforest. KEY RESULTS: We identified cultivated genotypes and cultivated-wild hybrids in zones with clear anthropogenic activity, and where cultivated C. canephora in home gardens may serve as a source for crop-to-wild gene flow. We found relatively few hybrids and backcrosses in the rainforests. CONCLUSIONS: The cultivation of C. canephora in close proximity to its wild gene pool has led to cultivated genotypes and cultivated-wild hybrids appearing within the natural habitats of C. canephora. Yet, given the high genetic similarity between the cultivated and wild gene pool, together with the relatively low incidence of hybridization, our results indicate that the overall impact in terms of risk of introgression remains limited so far.


Asunto(s)
Coffea , Flujo Génico , Coffea/genética , República Democrática del Congo , Productos Agrícolas/genética , Hibridación Genética , Bosque Lluvioso , Genotipo
12.
Nat Commun ; 15(1): 2286, 2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38480728

RESUMEN

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging cause of human infection with invasive disease incidence and clinical manifestations comparable to the closely related species, Streptococcus pyogenes. Through systematic genomic analyses of 501 disseminated SDSE strains, we demonstrate extensive overlap between the genomes of SDSE and S. pyogenes. More than 75% of core genes are shared between the two species with one third demonstrating evidence of cross-species recombination. Twenty-five percent of mobile genetic element (MGE) clusters and 16 of 55 SDSE MGE insertion regions were shared across species. Assessing potential cross-protection from leading S. pyogenes vaccine candidates on SDSE, 12/34 preclinical vaccine antigen genes were shown to be present in >99% of isolates of both species. Relevant to possible vaccine evasion, six vaccine candidate genes demonstrated evidence of inter-species recombination. These findings demonstrate previously unappreciated levels of genomic overlap between these closely related pathogens with implications for streptococcal pathobiology, disease surveillance and prevention.


Asunto(s)
Infecciones Estreptocócicas , Streptococcus , Vacunas , Humanos , Streptococcus pyogenes/genética , Flujo Génico
13.
Proc Natl Acad Sci U S A ; 121(12): e2316008121, 2024 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-38466849

RESUMEN

Introgression is pervasive across the tree of life but varies across taxa, geography, and genomic regions. However, the factors modulating this variation and how they may be affected by global change are not well understood. Here, we used 200 genomes and a 15-y site-specific environmental dataset to investigate the effects of environmental variation and mating system divergence on the magnitude of introgression between a recently diverged outcrosser-selfer pair of annual plants in the genus Clarkia. These sister taxa diverged very recently and subsequently came into secondary sympatry where they form replicated contact zones. Consistent with observations of other outcrosser-selfer pairs, we found that introgression was asymmetric between taxa, with substantially more introgression from the selfer to the outcrosser. This asymmetry was caused by a bias in the direction of initial F1 hybrid formation and subsequent backcrossing. We also found extensive variation in the outcrosser's admixture proportion among contact zones, which was predicted nearly entirely by interannual variance in spring precipitation. Greater fluctuations in spring precipitation resulted in higher admixture proportions, likely mediated by the effects of spring precipitation on the expression of traits that determine premating reproductive isolation. Climate-driven hybridization dynamics may be particularly affected by global change, potentially reshaping species boundaries and adaptation to novel environments.


Asunto(s)
Clarkia , Clarkia/genética , Reproducción , Aislamiento Reproductivo , Hibridación Genética , Genoma , Flujo Génico
14.
Mol Phylogenet Evol ; 195: 108054, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38471599

RESUMEN

The phylogeny and systematics of the genus Allium have been studied with a variety of diverse data types, including an increasing amount of molecular data. However, strong phylogenetic discordance and high levels of uncertainty have prevented the identification of a consistent phylogeny. The difficulty in establishing phylogenetic consensus and evidence for genealogical discordance make Allium a compelling test case to assess the relative contribution of incomplete lineage sorting (ILS), gene flow and gene tree estimation error on phylogenetic reconstruction. In this study, we obtained 75 transcriptomes of 38 Allium species across 10 subgenera. Whole plastid genome, single copy genes and consensus CDS were generated to estimate phylogenetic trees both using coalescence and concatenation methods. Multiple approaches including coalescence simulation, quartet sampling, reticulate network inference, sequence simulation, theta of ILS and reticulation index were carried out across the CDS gene trees to investigate the degrees of ILS, gene flow and gene tree estimation error. Afterward, a regression analysis was used to test the relative contributions of each of these forms of uncertainty to the final phylogeny. Despite extensive topological discordance among gene trees, we found a fully supported species tree that agrees with the most of well-accepted relationships and establishes monophyly of the genus Allium. We presented clear evidence for substantial ILS across the phylogeny of Allium. Further, we identified two ancient hybridization events for the formation of the second evolutionary line and subg. Butomissa as well as several introgression events between recently diverged species. Our regression analysis revealed that gene tree inference error and gene flow were the two most dominant factors explaining for the overall gene tree variation, with the difficulty in disentangling the effects of ILS and gene tree estimation error due to a positive correlation between them. Based on our efforts to mitigate the methodological errors in reconstructing trees, we believed ILS and gene flow are two principal reasons for the oft-reported phylogenetic heterogeneity of Allium. This study presents a strongly-supported and well-resolved phylogenetic backbone for the sampled Allium species, and exemplifies how to untangle heterogeneity in phylogenetic signal and reconstruct the true evolutionary history of the target taxa.


Asunto(s)
Flujo Génico , Filogenia , Simulación por Computador
15.
Infect Genet Evol ; 120: 105584, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38521481

RESUMEN

Management of Dermanyssus gallinae, a cosmopolitan hematophagous mite responsible for damage in layer poultry farming, is hampered by a lack of knowledge of its spatio-temporal population dynamics. Previous studies have shown that the circulation of this pest between farms is of strictly anthropogenic origin, that a mitochondrial haplogroup has been expanding on European farms since the beginning of the 21st century and that its local population growth may be particularly rapid. To refine our understanding of how D. gallinae spreads within and among farms, we characterized the genetic structure of mite populations at different spatial scales and sought to identify the main factors interrupting gene flow between poultry houses and between mitochondrial haplogroups. To this end, we selected and validated the first set of nuclear microsatellite markers for D. gallinae and sequenced a region of the CO1-encoding mitochondrial gene in a subsample of microsatellite-genotyped mites. We also tested certain conditions required for effective contamination of a poultry house through field experimentation, and conducted a survey of practices during poultry transfers. Our results confirm the role of poultry transport in the dissemination of mite populations, but the frequency of effective contamination after the introduction of contaminated material into poultry houses seems lower than expected. The high persistence of mites on farms, even during periods when poultry houses are empty and cleaned, and the very large number of nodes in the logistic network (large number of companies supplying pullets or transporting animals) undoubtedly explain the very high prevalence on farms. Substantial genetic diversity was measured in farm populations, probably as a result of the mite's known haplodiploid mode of sexual reproduction, coupled with the dense logistic network. The possibility of the occasional occurrence of asexual reproduction in this sexually reproducing mite was also revealed in our analyses, which could explain the extreme aggressiveness of its demographic dynamics under certain conditions.


Asunto(s)
Repeticiones de Microsatélite , Infestaciones por Ácaros , Ácaros , Animales , Ácaros/genética , Infestaciones por Ácaros/veterinaria , Infestaciones por Ácaros/parasitología , Enfermedades de las Aves de Corral/parasitología , Pollos/parasitología , Aves de Corral/parasitología , Granjas , Flujo Génico , Haplotipos , Variación Genética
16.
PLoS Biol ; 22(3): e3002460, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38498548

RESUMEN

A recent study questioned the use of branch length methods to assess the relative timing of horizontal gene transfers because of the effects of so-called "ghost" lineages. This Formal Comment discusses key considerations regarding the potential effect of missing lineages when assessing relative timing of evolutionary events.


Asunto(s)
Evolución Biológica , Flujo Génico , Filogenia , Transferencia de Gen Horizontal
17.
Mol Ecol ; 33(7): e17307, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38444224

RESUMEN

Upright branching sponges, such as Aplysina cauliformis, provide critical three-dimensional habitat for other organisms and assist in stabilizing coral reef substrata, but are highly susceptible to breakage during storms. Breakage can increase sponge fragmentation, contributing to population clonality and inbreeding. Conversely, storms could provide opportunities for new genotypes to enter populations via larval recruitment, resulting in greater genetic diversity in locations with frequent storms. The unprecedented occurrence of two Category 5 hurricanes in close succession during 2017 in the U.S. Virgin Islands (USVI) provided a unique opportunity to evaluate whether recolonization of newly available substrata on coral reefs was due to local (e.g. re-growth of remnants, fragmentation, larval recruitment) or remote (e.g. larval transport and immigration) sponge genotypes. We sampled A. cauliformis adults and juveniles from four reefs around St. Thomas and two in St. Croix (USVI). Using a 2bRAD protocol, all samples were genotyped for single-nucleotide polymorphisms (SNPs). Results showed that these major storm events favoured sponge larval recruitment but did not increase the genetic diversity of A. cauliformis populations. Recolonization of substratum post-storms via clonality was lower (15%) than expected and instead was mainly due to sexual reproduction (85%) via local larval recruitment. Storms did enhance gene flow among and within reef sites located south of St. Thomas and north of St. Croix. Therefore, populations of clonal marine species with low pelagic dispersion, such as A. cauliformis, may benefit from increased frequency and magnitude of hurricanes for the maintenance of genetic diversity and to combat inbreeding, enhancing the resilience of Caribbean sponge communities to extreme storm events.


Asunto(s)
Antozoos , Tormentas Ciclónicas , Animales , Flujo Génico , Arrecifes de Coral , Ecosistema , Región del Caribe
18.
Nat Commun ; 15(1): 2122, 2024 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-38459017

RESUMEN

Speciation is a continuous process driven by genetic, geographic, and ecological barriers to gene flow. It is widely investigated in multicellular eukaryotes, yet we are only beginning to comprehend the relative importance of mechanisms driving the emergence of barriers to gene flow in microbial populations. Here, we explored the diversification of the nearly ubiquitous soil cyanobacterium Microcoleus. Our dataset consisted of 291 genomes, of which 202 strains and eight herbarium specimens were sequenced for this study. We found that Microcoleus represents a global speciation continuum of at least 12 lineages, which radiated during Eocene/Oligocene aridification and exhibit varying degrees of divergence and gene flow. The lineage divergence has been driven by selection, geographical distance, and the environment. Evidence of genetic divergence and selection was widespread across the genome, but we identified regions of exceptional differentiation containing candidate genes associated with stress response and biosynthesis of secondary metabolites.


Asunto(s)
Flujo Genético , Especiación Genética , Flujo Génico , Genoma , Filogenia
19.
Mol Ecol ; 33(8): e17317, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38488670

RESUMEN

Genomes are heterogeneous during the early stages of speciation, with small 'islands' of DNA appearing to reflect strong adaptive differences, surrounded by vast seas of relative homogeneity. As species diverge, secondary contact zones between them can act as an interface and selectively filter through advantageous alleles of hybrid origin. Such introgression is another important adaptive process, one that allows beneficial mosaics of recombinant DNA ('rivers') to flow from one species into another. Although genomic islands of divergence appear to be associated with reproductive isolation, and genomic rivers form by adaptive introgression, it is unknown whether islands and rivers tend to be the same or different loci. We examined three replicate secondary contact zones for the Yosemite toad (Anaxyrus canorus) using two genomic data sets and a morphometric data set to answer the questions: (1) How predictably different are islands and rivers, both in terms of genomic location and gene function? (2) Are the adaptive genetic trait loci underlying tadpole growth and development reliably islands, rivers or neither? We found that island and river loci have significant overlap within a contact zone, suggesting that some loci are first islands, and later are predictably converted into rivers. However, gene ontology enrichment analysis showed strong overlap in gene function unique to all island loci, suggesting predictability in overall gene pathways for islands. Genome-wide association study outliers for tadpole development included LPIN3, a lipid metabolism gene potentially involved in climate change adaptation, that is island-like for all three contact zones, but also appears to be introgressing (as a river) across one zone. Taken together, our results suggest that adaptive divergence and introgression may be more complementary forces than currently appreciated.


Asunto(s)
Genética de Población , Transcriptoma , Transcriptoma/genética , Estudio de Asociación del Genoma Completo , Genoma , Genómica , Flujo Génico , Especiación Genética , Hibridación Genética , Aislamiento Reproductivo
20.
Heredity (Edinb) ; 132(4): 211-220, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38472424

RESUMEN

Inbreeding can reduce offspring fitness and has substantial implications for the genetic diversity and long-term viability of populations. In social cooperative canids, inbreeding is conditioned by the geographic proximity between opposite-sex kin outside natal groups and the presence of related individuals in neighbouring groups. Consequently, challenges in moving into other regions where the species is present can also affect inbreeding rates. These can be particularly problematic in areas of high human density, where movement can be restricted, even for highly vagile species. In this study, we investigate the socio-ecological dynamics of Iberian wolf packs in the human-dominated landscape of Alto Minho, in northwest Portugal, where wolves exhibit a high prevalence of short-distance dispersal and limited gene flow with neighbouring regions. We hypothesise that mating occurs regardless of relatedness, resulting in recurrent inbreeding due to high kin encounter rates. Using data from a 10-year non-invasive genetic monitoring programme and a combination of relatedness estimates and genealogical reconstructions, we describe genetic diversity, mate choice, and dispersal strategies among Alto Minho packs. In contrast with expectations, our findings reveal relatedness-based mate choice, low kin encounter rates, and a reduced number of inbreeding events. We observed a high prevalence of philopatry, particularly among female breeders, with the most common breeding strategy involving the pairing of a philopatric female with an unrelated immigrant male. Overall, wolves were not inbred, and temporal changes in genetic diversity were not significant. Our findings are discussed, considering the demographic trend of wolves in Alto Minho and its human-dominated landscape.


Asunto(s)
Endogamia , Lobos , Humanos , Animales , Masculino , Femenino , Lobos/genética , Cruzamiento , Reproducción/genética , Flujo Génico , Conducta Sexual Animal
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