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1.
Science ; 370(6513)2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33033187

RESUMO

Chen and Pfennig (Reports, 20 March 2020, p. 1377) analyze the fitness consequences of hybridization in toads but do not account for differences in survival among progeny. Apparent fitness effects depend on families with anomalously low survival, yet survival is crucial to evolutionary fitness. This and other analytical shortcomings demonstrate that a conclusion of adaptive mate choice is not yet justified.


Assuntos
Hibridização Genética , Comportamento Sexual Animal , Animais , Evolução Biológica , Feminino , Hibridização de Ácido Nucleico , Reprodução
2.
Science ; 370(6513)2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33033188

RESUMO

Braun et al contend that we did not account for survival, but we did. Differential survival does not alter our conclusions, which were also robust to removing anomalous families. They ignore the study system's natural history justifying our fitness measures, while failing to account for our behavioral data. We stand by our conclusion that females adaptively choose among heterospecific males.


Assuntos
Hibridização Genética , Comportamento Sexual Animal , Animais , Feminino , Masculino , Hibridização de Ácido Nucleico , Reprodução
3.
Proc Biol Sci ; 287(1934): 20200941, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32900317

RESUMO

Adaptive radiations (ARs) frequently show remarkable repeatability where single lineages undergo multiple independent episodes of AR in distant places and long-separate time points. Genetic variation generated through hybridization between distantly related lineages can promote AR. This mechanism, however, requires rare coincidence in space and time between a hybridization event and opening of ecological opportunity, because hybridization generates large genetic variation only locally and it will persist only for a short period. Hence, hybridization seems unlikely to explain recurrent AR in the same lineage. Contrary to these expectations, our evolutionary computer simulations demonstrate that admixture variation can geographically spread and persist for long periods if the hybrid population becomes separated into isolated sub-lineages. Subsequent secondary hybridization of some of these can reestablish genetic polymorphisms from the ancestral hybridization in places far from the birthplace of the hybrid clade and long after the ancestral hybridization event. Consequently, simulations revealed conditions where exceptional genetic variation, once generated through a rare hybridization event, can facilitate multiple ARs exploiting ecological opportunities available at distant points in time and space.


Assuntos
Especiação Genética , Hibridização Genética , Animais , Evolução Biológica , Filogenia , Reprodução
4.
Nat Commun ; 11(1): 4778, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32963241

RESUMO

Obtaining genetic variation information from indica rice hybrid parents and identification of loci associated with heterosis are important for hybrid rice breeding. Here, we resequence 1,143 indica accessions mostly selected from the parents of superior hybrid rice cultivars of China, identify genetic variations, and perform kinship analysis. We find different hybrid rice crossing patterns between 3- and 2-line superior hybrid lines. By calculating frequencies of parental variation differences (FPVDs), a more direct approach for studying rice heterosis, we identify loci that are linked to heterosis, which include 98 in superior 3-line hybrids and 36 in superior 2-line hybrids. As a proof of concept, we find two accessions harboring a deletion in OsNramp5, a previously reported gene functioning in cadmium absorption, which can be used to mitigate rice grain cadmium levels through hybrid breeding. Resource of indica rice genetic variation reported in this study will be valuable to geneticists and breeders.


Assuntos
Variação Genética , Vigor Híbrido/genética , Oryza/genética , Cruzamento , Proteínas de Transporte de Cátions/genética , China , Cruzamentos Genéticos , Deleção de Genes , Genes de Plantas , Hibridização Genética , Oryza/classificação , Filogenia , Proteínas de Plantas/genética , Polimorfismo de Nucleotídeo Único
5.
Nat Commun ; 11(1): 4468, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32901021

RESUMO

Speciation constrains the flow of genetic information between populations of sexually reproducing organisms. Gaining control over mechanisms of speciation would enable new strategies to manage wild populations of disease vectors, agricultural pests, and invasive species. Additionally, such control would provide safe biocontainment of transgenes and gene drives. Here, we demonstrate a general approach to create engineered genetic incompatibilities (EGIs) in the model insect Drosophila melanogaster. EGI couples a dominant lethal transgene with a recessive resistance allele. Strains homozygous for both elements are fertile and fecund when they mate with similarly engineered strains, but incompatible with wild-type strains that lack resistant alleles. EGI genotypes can also be tuned to cause hybrid lethality at different developmental life-stages. Further, we demonstrate that multiple orthogonal EGI strains of D. melanogaster can be engineered to be mutually incompatible with wild-type and with each other. EGI is a simple and robust approach in multiple sexually reproducing organisms.


Assuntos
Drosophila melanogaster/genética , Engenharia Genética/métodos , Especiação Genética , Animais , Animais Geneticamente Modificados , Cruzamentos Genéticos , Feminino , Genes de Insetos , Genes Letais , Genótipo , Hibridização Genética , Masculino , Modelos Genéticos , Transgenes
6.
PLoS One ; 15(9): e0238419, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32915803

RESUMO

The objectives of this study were: i) to classify animals into groups of high and low feed efficiency (FE) using three FE indexes (Residual feed intake (RFI), Residual weight gain (RG) and Feed conversion efficiency (FCE)), and ii) to evaluate whether crossbreed Holstein x Gyr heifers divergent for FE indexes exhibit differences in nutrient intake and digestibility, energy partitioning, heat production, methane emissions, nitrogen partitioning and blood parameters. Thirty-five heifers were housed in a tie-stall, received ad libitum TMR (75:25, corn silage: concentrate) and were ranked and classified into high (HE) or low efficiency (LE) for RFI, RG and FCE. The number of animals for each HE group were 13 (< 0.5 standard deviation (SD) for RFI, 11 for RG and 11 for FCE (> 0.5 SD) and for the LE were 10 (> 0.5 SD) for RFI, 11 for RG and 12 for FCE (< 0.5 SD). Gas exchanges (O2 consumption, CO2 and CH4 production) in open-circuit respiratory chambers and whole tract digestibility trial was performed. A completely randomized experimental design was used and the data were analyzed by ANOVA and correlation study. High efficiency animals for RFI produced less CO2, consumed less O2 and had lower heat production (HP). Methane production was positively correlated with RFI. High efficiency RG had higher O2 consumption and CO2 production in relation to LE-RG. High efficiency FCE had greater NFC digestibility, higher positive energy balance (EB) and excreted (11.4 g/d) less nitrogen in urine. High efficiency RG and FCE groups emitted less CH4 per kg of weight gain than LE animals. Animals HE for RFI and FCE had lower ß-hydroxybutyrate and higher glucose concentrations, respectively. The differences in intake, digestibility, energy and nitrogen partition, CH4 emission, blood metabolic variables and heat production between the HE and LE groups varied according to the efficiency indexes adopted. The HP (kcal/d/BW0.75) was lower for HE animals for RFI and FCE indexes.


Assuntos
Bovinos/fisiologia , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Bovinos/sangue , Bovinos/classificação , Digestão , Ingestão de Alimentos , Metabolismo Energético , Feminino , Hibridização Genética , Metano/metabolismo , Nitrogênio/metabolismo , Troca Gasosa Pulmonar
7.
PLoS One ; 15(8): e0237455, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32777809

RESUMO

De novo assembly of sequence reads from next generation sequencing platforms is a common strategy for detecting presence and sequencing of viruses in biospecimens. Amplification artifacts and presence of several related viruses in the same specimen can lead to assembly of erroneous, chimeric sequences. We now report that such chimeras can also occur between viral and non-viral biological sequences incorrectly joined together which may cause erroneous detection of viruses, highlighting the importance of performing a chimera checking step in bioinformatics pipelines. Using Illumina NextSeq and metagenomic sequencing, we analyzed 80 consecutive non-melanoma skin cancers (NMSCs) from 11 immunosuppressed patients together with 11 NMSCs from patients who had only developed 1 NMSC. We aligned high-quality reads against a Human Papillomavirus (HPV) database and found HPV sequences in 9/91 specimens. A previous bioinformatic analysis of the same crude sequencing data from some of these samples had found an additional 3 specimens to be HPV-positive after performing de novo assembly. The reason for the discrepancy was investigated and found to be mostly caused by chimeric sequences containing both viral and non-viral sequences. Non-viral sequences were present in these 3 samples. To avoid erroneous detection of HPV when performing sequencing, we thus developed a novel script to identify HPV chimeric sequences.


Assuntos
Biologia Computacional , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Hibridização Genética , Algoritmos , Metagenômica , Papillomaviridae/genética
8.
Proc Biol Sci ; 287(1932): 20201459, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-32752983

RESUMO

Hybridization events are not uncommon in marine environments where physical barriers are attenuated. Studies of coral reef taxa have suggested that hybridization predominantly occurs between parapatric species distributed along biogeographic suture zones. By contrast, little is known about the extent of sympatric hybridization on coral reefs, despite the large amount of biogeographic overlap shared by many coral reef species. Here, we investigate if the propensity for hybridization along suture zones represents a general phenomenon among coral reef fishes, by focusing on the marine angelfishes (family Pomacanthidae). Although hybridization has been reported for this family, it has not been thoroughly surveyed, with more recent hybridization studies focusing instead on closely related species from a population genetics perspective. We provide a comprehensive survey of hybridization among the Pomacanthidae, characterize the upper limits of genetic divergences between hybridizing species and investigate the occurrence of sympatric hybridization within this group. We report the occurrence of hybridization involving 42 species (48% of the family) from all but one genus of the Pomacanthidae. Our results indicate that the marine angelfishes are among the groups of coral reef fishes with the highest incidences of hybridization, not only between sympatric species, but also between deeply divergent lineages.


Assuntos
Peixes/fisiologia , Hibridização Genética , Simpatria , Animais , Recifes de Corais , Fluxo Gênico , Genética Populacional
9.
PLoS One ; 15(8): e0236515, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764757

RESUMO

With the increasing availability of high quality genomic data, there is opportunity to deeply explore the genealogical relationships of different gene loci between closely related species. In this study, we utilized genomes of Xenopus laevis (XLA, a tetraploid species with (L) and (S) sub-genomes) and X. tropicalis (XTR, a diploid species) to investigate whether synonymous substitution rates among orthologous or homoeologous genes displayed any heterogeneity. From over 1500 orthologous/homoeologous genes collected, we calculated proportion of synonymous substitutions between genomes/sub-genomes (k) and found variation within and between chromosomes. Within most chromosomes, we identified higher k with distance from the centromere, likely attributed to higher substitution rates and recombination in these regions. Using maximum likelihood methods, we identified further evidence supporting rate heterogeneity, and estimated species divergence times and ancestral population sizes. Estimated species divergence times (XLA.L-XLA.S: ~25.5 mya; XLA-XTR: ~33.0 mya) were slightly younger compared to a past study, attributed to consideration of population size in our study. Meanwhile, we found very large estimated population size in the ancestral populations of the two species (NA = 2.55 x 106). Local hybridization and population structure, which have not yet been well elucidated in frogs, may be a contributing factor to these possible large population sizes.


Assuntos
Evolução Molecular , Genoma/genética , Mutação Silenciosa/genética , Xenopus laevis/genética , Animais , Cromossomos , Heterogeneidade Genética , Hibridização Genética , Hibridização in Situ Fluorescente , Filogenia
10.
PLoS One ; 15(8): e0235962, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760091

RESUMO

Wild relatives represent a source of variation for many traits of interest for eggplant (Solanum melongena) breeding, as well as for broadening its genetic base. However, interspecific hybridization with wild relatives has been barely used in eggplant breeding programs, and reproductive barriers have resulted in reduced seed numbers in interspecific combinations. The mechanism underlying this phenomenon remains unclear. We hybridized females of cultivated eggplant 177 (Solanum melongena) with males of wild relatives 53 and Y11 (Solanum aethiopicum). Self-crossed 177 was the control. The seed number per control fruit was significantly higher than that of the hybrids. Paraffin sections showed no significant difference between control and 177×53 and 177×Y11. Double fertilization began 4 days post-pollination. Sperm cells were fused with egg cells 6 days post-pollination. To understand the differences in molecular mechanisms underlying this process, transcriptomes of ovaries at 0, 4, and 6 days after self-crossing and hybridization were analyzed. We screened 22,311 differentially expressed genes (DEGs) between the control and hybrids 4 and 6 days post-pollination. A total of 497 DEGs were shared among all pollination combinations. These DEGs were enriched in plant hormone transduction, cell senescence, metabolism, and biosynthesis pathways. DEG clustering analysis indicated distinct expression patterns between the control and hybrids but not between the hybrids. The DEGs in hybrids involved secondary metabolic process, phenylpropanoid metabolic process, and carboxypeptidase activity, while those in the control involved xyloglucan metabolic process, auxin-activated signaling pathway, cell wall polysaccharide metabolic process, and xyloglucosyl transferase activity. Additionally, 1683 transcription factors, including members of the AP2-ERF, MYB, bHLH, and B3 families may play important roles in self-crossing and hybridization. Our results provide insights into the regulatory mechanisms underlying variations between ovaries of self-crossed and hybrid eggplants and a basis for future studies on crossbreeding Solanum and genetic mechanisms underlying double fertilization.


Assuntos
Regulação da Expressão Gênica de Plantas , Hibridização Genética , Melhoramento Vegetal/métodos , Solanum/genética , Fertilização/genética , Perfilação da Expressão Gênica , Polinização
11.
PLoS One ; 15(8): e0236351, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785293

RESUMO

Hybrid performance during wheat breeding can be improved by analyzing genetic distance (GD) among wheat genotypes and determining its correlation with heterosis. This study evaluated the GD between 16 wheat genotypes by using 60 simple sequence repeat (SSR) markers to classify them according to their relationships and select those with greater genetic diversity, evaluate the correlation of the SSR marker distance with heterotic performance and specific combining ability (SCA) for heat stress tolerance, and identify traits that most influence grain yield (GY). Eight parental genotypes with greater genetic diversity and their 28 F1 hybrids generated using diallel crossing were evaluated for 12 measured traits in two seasons. The GD varied from 0.235 to 0.911 across the 16 genotypes. Cluster analysis based on the GD estimated using SSRs classified the genotypes into three major groups and six sub-groups, almost consistent with the results of principal coordinate analysis. The combined data indicated that five hybrids showed 20% greater yield than mid-parent or better-parent. Two hybrids (P2 × P4) and (P2 × P5), which showed the highest performance of days to heading (DH), grain filling duration (GFD), and GY, and had large genetic diversity among themselves (0.883 and 0.911, respectively), were deemed as promising heat-tolerant hybrids. They showed the best mid-parent heterosis and better-parent heterosis (BPH) for DH (-11.57 and -7.65%; -13.39 and -8.36%, respectively), GFD (12.74 and 12.17%; 12.09 and 10.59%, respectively), and GY (36.04 and 20.04%; 44.06 and 37.73%, respectively). Correlation between GD and each of BPH and SCA effects based on SSR markers was significantly positive for GFD, hundred kernel weight, number of kernels per spike, harvest index, GY, and grain filling rate and was significantly negative for DH. These correlations indicate that the performance of wheat hybrids with high GY and earliness could be predicted by determining the GD of the parents by using SSR markers. Multivariate analysis (stepwise regression and path coefficient) suggested that GFD, hundred kernel weight, days to maturity, and number of kernels per spike had the highest influence on GY.


Assuntos
Resposta ao Choque Térmico/genética , Vigor Híbrido/genética , Seleção Genética/genética , Triticum/genética , Pão , Cruzamento , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Flores/genética , Flores/crescimento & desenvolvimento , Genótipo , Humanos , Hibridização Genética/genética , Repetições de Microssatélites/genética , Fenótipo , Triticum/crescimento & desenvolvimento
12.
Nat Commun ; 11(1): 3670, 2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32728126

RESUMO

Our understanding of polyploid genome evolution is constrained because we cannot know the exact founders of a particular polyploid. To differentiate between founder effects and post polyploidization evolution, we use a pan-genomic approach to study the allotetraploid Brachypodium hybridum and its diploid progenitors. Comparative analysis suggests that most B. hybridum whole gene presence/absence variation is part of the standing variation in its diploid progenitors. Analysis of nuclear single nucleotide variants, plastomes and k-mers associated with retrotransposons reveals two independent origins for B. hybridum, ~1.4 and ~0.14 million years ago. Examination of gene expression in the younger B. hybridum lineage reveals no bias in overall subgenome expression. Our results are consistent with a gradual accumulation of genomic changes after polyploidization and a lack of subgenome expression dominance. Significantly, if we did not use a pan-genomic approach, we would grossly overestimate the number of genomic changes attributable to post polyploidization evolution.


Assuntos
Brachypodium/genética , Diploide , Evolução Molecular , Genoma de Planta , Poliploidia , Cromossomos de Plantas/genética , Genoma de Cloroplastos , Genômica , Hibridização Genética , Filogenia , Polimorfismo de Nucleotídeo Único , Retroelementos/genética , Especificidade da Espécie
13.
Nat Commun ; 11(1): 3375, 2020 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-32632155

RESUMO

Hybridization can drive speciation. We examine the hypothesis that Castanea henryi var. omeiensis is an evolutionary lineage that originated from hybridization between two near-sympatric diploid taxa, C. henryi var. henryi and C. mollissima. We produce a high-quality genome assembly for mollissima and characterize evolutionary relationships among related chestnut taxa. Our results show that C. henryi var. omeiensis has a mosaic genome but has accumulated divergence in all 12 chromosomes. We observe positive correlation between admixture proportions and recombination rates across the genome. Candidate barrier genomic regions, which isolate var. henryi and mollissima, are re-assorted in the hybrid lineage. We further find that the putative barrier segments concentrate in genomic regions with less recombination, suggesting that interaction between natural selection and recombination shapes the evolution of hybrid genomes during hybrid speciation. This study highlights that reassortment of parental barriers is an important mechanism in generating biodiversity.


Assuntos
Diploide , Fagaceae/genética , Genoma de Planta/genética , Hibridização Genética , Mosaicismo , Ploidias , Algoritmos , Evolução Molecular , Fagaceae/classificação , Especiação Genética , Modelos Genéticos , Recombinação Genética , Seleção Genética , Especificidade da Espécie , Sequenciamento Completo do Genoma/métodos
14.
Environ Pollut ; 266(Pt 1): 115074, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32629209

RESUMO

Several populations of the amphipod, Hyalella azteca, have developed resistance to pyrethroid insecticides due to non-target exposure, but the dominance of the resistance trait is unknown. The current study investigated the dominance level of point mutations in natural populations of insecticide-resistant H. azteca and determined whether H. azteca from different clades with and without resistant alleles can hybridize and produce viable offspring. A parent generation (P0) of non-resistant homozygous wild type H. azteca was crossbred with pyrethroid-resistant homozygous mutant animals and the tolerance of the filial 1 (F1) generation to the pyrethroid insecticide, permethrin, was measured. Then the genotypes of the F1 generation was examined to assure heterozygosity. The resistant parents had permethrin LC50 values that ranged from 52 to 82 times higher than the non-resistant animals and both crossbreeding experiments produced heterozygous hybrid offspring that had LC50 values similar to the non-resistant H. azteca parent. Dominance levels calculated for each of the crosses showed values close to 0, confirming that the L925I and L925V mutations were completely recessive. The lack of reproduction by hybrids of the C x D breeding confirmed that these clades are reproductively isolated and therefore introgression of adaptive alleles across these clades is unlikely. Potential evolutionary consequences of this selection include development of population bottlenecks, which may arise leading to fitness costs and reduced genetic diversity of H. azteca.


Assuntos
Anfípodes , Inseticidas/análise , Piretrinas , Poluentes Químicos da Água/análise , Animais , Hibridização Genética , Resistência a Inseticidas , Permetrina
15.
PLoS One ; 15(7): e0235789, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645117

RESUMO

Eisenia andrei (Ea) and E. fetida (Ef) lumbricid earthworms are simultaneous hermaphrodites potentially capable of self-fertilization and hybridization. We have shown previously that reproductive isolation in these species is incomplete in Ea and Ef earthworms of French provenance, as viable offspring appeared in inter-specific pairs. Fertile asymmetric hybrids developed from Ea-derived ova fertilized by Ef-derived spermatozoa, as well as Ea or Ef specimens derived after self-fertilization (resulting from admixture of endogenously produced spermatozoa with sperm from a partner), but never Ef-hybrids from Ef-ova fertilized by Ea-spermatozoa. The latter appeared only in backcrosses of Ea-hybrids with the Ef. Here we show that these phenomena are not unique for French Ea/Ef earthworms, but are shared by earthworms from French, Hungarian, and Polish laboratory cultures. Semi-quantitative studies on fertility of Ea-derived hybrids revealed gradually decreasing numbers of offspring in three successive generations, more rapid in backcrosses with Ef than with Ea, and the absence of progeny in pairs of hybrids, despite the presence of cocoons in almost all pairs. Based on species specific mitochondrial and nuclear DNA sequences, we provide the first examples of two unique sterile hybrids with mitonuclear mismatch and potential mitonuclear incompatibility among offspring of one of the hybrid+Ef pairs. Earthworms from the investigated populations did not reproduce when kept from hatching in isolation or with representatives of Dendrobaena veneta but started reproducing upon recognition of a related partner, such as Ea, Ef or their hybrids. The existence of Ea or Ef specimens among offspring of hybrid+Ea/Ef pairs might be explained either by partner-induced self-fertilization of Ea/Ef or hybrid-derived ova, or by cross-fertilization of Ea/Ef /hybrid ova by partner-derived spermatozoa; the latter might contribute to interspecific gene introgression.


Assuntos
Oligoquetos/fisiologia , Animais , Feminino , Fertilidade , Fertilização , França , Hungria , Hibridização Genética , Masculino , Oligoquetos/genética , Polônia , Reprodução , Isolamento Reprodutivo , Especificidade da Espécie , Espermatozoides/metabolismo
17.
Sci Total Environ ; 740: 140046, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32563876

RESUMO

Genetic diversity is expected to erode in disturbed habitats through strong selection, local extinctions, and recolonization associated with genetic bottlenecks and restricted gene flow. Despite this general prediction and over three decades of population genetics studies, our understanding of the long-term effect of environmental disturbance on local and regional genetic diversity remains limited. We conducted a population genetic survey of the microcrustacean Daphnia across a landscape subject to anthropogenic stressors from a century of industrial mining. At the local scale we found moderate genetic diversity (i.e., low clonal diversity), characteristic of habitat-specific selective sweeps and local extinctions, but high diversity and strong genetic structure at the regional scale despite the shared watershed of many lakes and exceptional dispersal ability of daphniids. Many habitats experienced changes in species assemblages, with the obligate asexual Daphnia pulex lineages-known only to inhabit ponds-dominating disrupted urban lakes. This habitat transition (pond to lake) was likely facilitated by the disruption of ecological barriers maintaining the genomic separation of these young species. Thus, disrupted habitats can exhibit complex and unexpected genetic patterns of local extinctions and recolonizations, followed by habitat transitions, hybridization and potential speciation events that are difficult to predict and should not be underestimated.


Assuntos
Genética Populacional , Hibridização Genética , Animais , Ecossistema , Fluxo Gênico , Variação Genética
18.
Am J Bot ; 107(6): 923-940, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32498125

RESUMO

PREMISE: Delimiting biodiversity units is difficult in organisms in which differentiation is obscured by hybridization, plasticity, and other factors that blur phenotypic boundaries. Such work is more complicated when the focal units are subspecies, the definition of which has not been broadly explored in the era of modern genetic methods. Eastwood manzanita (Arctostaphylos glandulosa Eastw.) is a widely distributed and morphologically complex chaparral shrub species with much subspecific variation, which has proven challenging to categorize. Currently 10 subspecies are recognized, however, many of them are not geographically segregated, and morphological intermediates are common. Subspecies delimitation is of particular importance in this species because two of the subspecies are rare. The goal of this study was to apply an evolutionary definition of "subspecies" to characterize structure within Eastwood manzanita. METHODS: We used publicly available geospatial environmental data and reduced-representation genome sequencing to characterize environmental and genetic differentiation among subspecies. In addition, we tested whether subspecies could be differentiated by environmentally associated genetic variation. RESULTS: Our analyses do not show genetic differentiation among subspecies of Eastwood manzanita, with the exception of one of the two rare subspecies. In addition, our environmental analyses did not show ecological differentiation, though limitations of the analysis prevent strong conclusions. CONCLUSIONS: Genetic structure within Eastwood manzanita does not correspond to current subspecies circumscriptions, but rather reflects geographic distribution. Our study suggests that subspecies concepts need to be reconsidered in long-lived plant species, especially in the age of next-generation sequencing.


Assuntos
Evolução Biológica , Deriva Genética , Biodiversidade , Variação Genética , Sequenciamento de Nucleotídeos em Larga Escala , Hibridização Genética , Filogenia
19.
Proc Biol Sci ; 287(1928): 20200690, 2020 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-32486979

RESUMO

Numerous pairs of evolutionarily divergent mammalian species have been shown to produce hybrid offspring. In some cases, F1 hybrids are able to produce F2s through matings with F1s. In other instances, the hybrids are only able to produce offspring themselves through backcrosses with a parent species owing to unisexual sterility (Haldane's Rule). Here, we explicitly tested whether genetic distance, computed from mitochondrial and nuclear genes, can be used as a proxy to predict the relative fertility of the hybrid offspring resulting from matings between species of terrestrial mammals. We assessed the proxy's predictive power using a well-characterized felid hybrid system, and applied it to modern and ancient hominins. Our results revealed a small overlap in mitochondrial genetic distance values that distinguish species pairs whose calculated distances fall within two categories: those whose hybrid offspring follow Haldane's Rule, and those whose hybrid F1 offspring can produce F2s. The strong correlation between genetic distance and hybrid fertility demonstrated here suggests that this proxy can be employed to predict whether the hybrid offspring of two mammalian species will follow Haldane's Rule.


Assuntos
Evolução Biológica , Hibridização Genética , Mamíferos , Animais , Fertilidade , Deriva Genética , Infertilidade , Mitocôndrias/genética , Reprodução
20.
An Acad Bras Cienc ; 92 Suppl 1: e20180874, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32491135

RESUMO

In plant breeding, the dialelic models univariate have aided the selection of parents for hybridization. Multivariate analyses allow combining and associating the multiple pieces of information of the genetic relationships between traits. Therefore, multivariate analyses might refine the discrimination and selection of the parents with greater potential to meet the goals of a plant breeding program. Here, we propose a method of multivariate analysis used for stablishing mega-traits (MTs) in diallel trials. The proposed model is applied in the evaluation of a multi-environment complete diallel trial with 90 F1's of simple maize hybrids. From a set of 14 traits, we demonstrated how establishing and interpreting MTs with agronomic implication. The diallel analyzes based on mega-traits present an important evolution in statistical procedures since the selection is based on several traits. We believe that the proposed method fills an important gap of plant breeding. In our example, three MTs were established. The first, formed by plant stature-related traits, the second by tassel size-related traits, and the third by grain yield-related traits. Individual and joint diallel analysis using the established MTs allowed identifying the best hybrid combinations for achieving F1's with lower plant stature, tassel size, and higher grain yield.


Assuntos
Hibridização Genética/genética , Melhoramento Vegetal/métodos , Zea mays/genética , Análise Fatorial , Genótipo , Análise Multivariada , Fenótipo , Zea mays/crescimento & desenvolvimento
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