Genetic Divergence
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Udit Kumar ◽  
Pramila . ◽  
K. Prasad ◽  
R.K. Tiwari ◽  
Saipayan Ghosh ◽  

Background: Dolichos bean is an important leguminous vegetable having a wide range of variation in different quantitative characters. Assessing genetic diversity among dolichos bean accessions can ensure development of suitable high-yielding and adapted varieties with suitable maturity period. Methods: Fifteen genotypes were evaluated for different characters in Dolichos bean at two locations of Dr. Rajendra Prasad Central Agricultural University viz. Vegetable Research Farm, Pusa and Krishi Vigyan Kendra, Birauli, Samastipur, Bihar during the year 2018-19 and pooled data was analyzed. The genotypes were evaluated for genetic variability and genetic divergence for 14 characters. For the assessment of genetic diversity among the fifteen genotypes of dolichos bean, Mahalanobis (D2) statistic (Mahalanobis, 1936) was used, following the procedure given by Rao, 1952. Grouping of genotypes into clusters was done using Tocher’s method as described by Rao, 1952. Result: Phenotypic Coefficient of Variation (PCV) was slightly higher than Genotypic Coefficient of Variation (GCV) for all the characters indicated that the characters were less influenced by environment. The characters having high heritability and high genetic advance include harvesting duration, number of pods per plant, pod length, pod diameter, individual pod weight, weight of seeds per pod, 100 fresh green seed weight, pod yield and percent incidence of yellow mosaic virus. Therefore, selection for above characters is highly effective. Genetic diversity analysis evaluated that all genotypes could be placed into 6 clusters. Genotypes grouped in Cluster III and I have highest mean value for all characters as well as highest inter-cluster distance.

Zootaxa ◽  
2021 ◽  
Vol 5006 (1) ◽  
pp. 127-168

Four new species of the Palaearctic crangonyctid amphipod genus Lyurella Derzhavin, 1939 (Crustacea: Amphipoda: Crangonyctidae), L. mikhailovi sp. n., L. fanagorica sp. n., L. fontinalis sp. n. and L. asheensis sp. n., are described based on an integrative approach from the subterranean habitats of the southwestern foothills of the Greater Caucasian Ridge (the north-eastern Black Sea coast). Despite the relative proximity of the habitats, the interspecific genetic divergence (by COI mtDNA gene marker) between the newly outlined Caucasian species of the genus varied from 11 to 21%, demonstrating a long-term isolation and lack of gene flow for at least 3–7Mya, starting from the Pliocene. The lowest genetic divergence between L. shepsiensis Sidorov, 2015 and L. asheensis sp. n., estimated as 4%, is also considered species-specific due to the presence of distinct morphological differences. We discuss the phylogeny, morphology, and distribution and provide a key for all known species of Lyurella. DNA barcoding data for all species, including the type species of the genus, Lyurella hyrcana Derzhavin, 1939, are presented for the first time.

2021 ◽  
Vol 9 ◽  
Adam D. Leaché ◽  
Hayden R. Davis ◽  
Sonal Singhal ◽  
Matthew K. Fujita ◽  
Megan E. Lahti ◽  

Phylogenomic investigations of biodiversity facilitate the detection of fine-scale population genetic structure and the demographic histories of species and populations. However, determining whether or not the genetic divergence measured among populations reflects species-level differentiation remains a central challenge in species delimitation. One potential solution is to compare genetic divergence between putative new species with other closely related species, sometimes referred to as a reference-based taxonomy. To be described as a new species, a population should be at least as divergent as other species. Here, we develop a reference-based taxonomy for Horned Lizards (Phrynosoma; 17 species) using phylogenomic data (ddRADseq data) to provide a framework for delimiting species in the Greater Short-horned Lizard species complex (P. hernandesi). Previous species delimitation studies of this species complex have produced conflicting results, with morphological data suggesting that P. hernandesi consists of five species, whereas mitochondrial DNA support anywhere from 1 to 10 + species. To help address this conflict, we first estimated a time-calibrated species tree for P. hernandesi and close relatives using SNP data. These results support the paraphyly of P. hernandesi; we recommend the recognition of two species to promote a taxonomy that is consistent with species monophyly. There is strong evidence for three populations within P. hernandesi, and demographic modeling and admixture analyses suggest that these populations are not reproductively isolated, which is consistent with previous morphological analyses that suggest hybridization could be common. Finally, we characterize the population-species boundary by quantifying levels of genetic divergence for all 18 Phrynosoma species. Genetic divergence measures for western and southern populations of P. hernandesi failed to exceed those of other Phrynosoma species, but the relatively small population size estimated for the northern population causes it to appear as a relatively divergent species. These comparisons underscore the difficulties associated with putting a reference-based approach to species delimitation into practice. Nevertheless, the reference-based approach offers a promising framework for the consistent assessment of biodiversity within clades of organisms with similar life histories and ecological traits.

2021 ◽  
Vol 35 (4) ◽  
pp. 562-577
Paulo Henrique Silva ◽  
Suelen Alves Vianna ◽  
Cássia Regina Limonta Carvalho ◽  
Joaquim Adelino de Azevedo Filho ◽  
Carlos Augusto Colombo

Divergência genética entre espécies de palmeiras Acrocomia Mart. baseada em descritores morfoagronômicos   PAULO HENRIQUE DA SILVA1, SUELEN ALVES VIANNA2, CÁSSIA REGINA LIMONTA CARVALHO3, JOAQUIM ADELINO DE AZEVEDO FILHO4, CARLOS AUGUSTO COLOMBO5   1 Mestrando no Curso de Pós-Graduação em Agricultura Tropical e Subtropical – Genética, Melhoramento e Biotecnologia Vegetal- Instituto Agronômico (IAC). Avenida: Barão de Itapura, 1481, Botafogo, Campinas, SP, Brasil, CEP: 13.020-902.  [email protected] 2 Pós Doutoranda no Centro de Pesquisa & Desenvolvimento de Recursos Genéticos Vegetais, Laboratório de Biologia Molecular – Instituto Agronômico (IAC). Avenida: Barão de Itapura, 1481, Botafogo, Campinas, SP, Brasil, CEP: 13.020-902.  [email protected] 3 Pesquisadora no Centro de Pesquisa & Desenvolvimento de Recursos Genéticos Vegetais, Laboratório de Fitoquímica – Instituto Agronômico (IAC). Avenida: Barão de Itapura, 1481, Botafogo, Campinas, SP, Brasil, CEP: 13.020-902.  [email protected] 4 Pesquisador na Agência Paulista de Tecnologia dos Agronegócios (APTA) - Pólo Regional do Leste Paulista. Rua: Dr. José Paiva Castro, 1493, Monte Alegre do Sul, SP, CEP: 13.910-000. [email protected] 5  Pesquisador no Centro de Pesquisa & Desenvolvimento de Recursos Genéticos Vegetais, Laboratório de Biologia Molecular – Instituto Agronômico (IAC). Avenida: Barão de Itapura, 1481, Botafogo, Campinas, SP, Brasil, CEP: 13.020-902.  [email protected]   Resumo: As palmeiras nativas Acrocomia aculeata e Acrocomia totai são utilizadas para diversos fins sobretudo, o uso da polpa fresca ou processada para alimentação e a extração de óleo da polpa e da amêndoa com diversas aplicações. Sabendo de seu potencial econômico e a dúvida existente sobre sua taxonomia, foi realizada a caracterização de 60 indivíduos em três populações de cada uma das espécies com o uso de 41 descritores morfoagronômicos. Os dados foram analisados com o uso de estatística univariada e multivariada (estimativa de similaridade pelo índice de Gower e formação dos agrupamentos pelo método UPGMA). Foi encontrada grande variação na maioria dos descritores analisados dentro e entre populações e espécies. A população de Luz-MG apresentou os maiores valores relativos aos descritores de frutos e a de Corumbá-MS os menores. A análise de agrupamento revelou a formação de dois grandes grupos correspondentes às espécies analisadas e a subdivisão dentro de cada um destes corresponde a sua origem geográfica. A variação encontrada dentro de cada uma das espécies pode orientar a seleção de indivíduos mais produtivos em programas de melhoramento e a divergência entre espécies além de comprovar sua taxonomia subsidia futuros estudos e sua melhor utilização.   Palavras-chave: Acrocomia aculeata, Acrocomia totai, Arecaceae, diversidade, pré-melhoramento   GENETIC DIVERGENCE AMONG SPECIES OF PALM TREES Acrocomia Mart. BASED ON MORPHOAGRONOMIC DESCRIPTORS   ABSTRACT: The native palm trees Acrocomia aculeata and Acrocomia totai are used for several purposes, mainly, the use of fresh or processed pulp for food and the extraction of oil from the pulp and almond with different applications. Knowing its economic potential and doubt about its taxonomy, 60 individuals were characterized in three populations of each species using 41 morpho-agronomic descriptors. The data were analyzed using univariate and multivariate statistics (similarity estimate using the Gower index and formation of clusters using the UPGMA method). Great variation was found in most of the descriptors analyzed within and between populations and species. The population of Luz-MG had the highest values ​​for fruit descriptors and the population of Corumbá-MS the lowest. The cluster analysis revealed the formation of two large groups corresponding to the analyzed species and the subdivision within each of these corresponds to their geographical origin. The variation found within each species can guide the selection of more productive individuals in breeding programs and the divergence between species, in addition to proving their taxonomy supports future studies and their better use.   Keywords: Acrocomia aculeata, Acrocomia totai, Arecaceae, diversity, pre-breeding.

Swosti S. Das ◽  
K. Kishore ◽  
D. Lenka ◽  
D. K. Dash ◽  
K. C. Samal ◽  

An experiment was conducted during 2018-2020 to study the genetic diversity in 24 morphological traits using D2 statistics in mango genotypes of eastern tropical region of India. Present study reveals that the clustering pattern based on D2 statistics grouped 40 genotypes of mango into 7 clusters, out of which cluster VI (7397.45) shows the highest intracluster value followed by cluster III (5346.99) and cluster V (4130.4), indicating considerable genetic divergence among the accessions of this cluster. While maximum inter- cluster distance was observed between the cluster VI and VII (300180) followed by cluster II and VI (289267.7) and cluster I and VI (214380.5) indicated that the accessions belonging to these groups were genetically most diverse and can be used as a parent in hybridization programme. Wide range of genetic diversity observed among cluster VI and cluster VII, can either be utilized for breeding programmes for genetic improvement in mango or directly adopted as a variety. Fruit yield exhibited significant contribution towards the genetic divergence (60.77%) followed by fruit weight (26.79%), stone percentage (4.74%), peel percentage (2.31%) and pulp percentage (2.05%).

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254413
João de Andrade Dutra Filho ◽  
Tercilio Calsa Júnior ◽  
Djalma Euzébio Simões Neto ◽  
Lauter Silva Souto ◽  
Anielson dos Santos Souza ◽  

The best agro-industrial performance presented by a crop genotype in one environment may not be reproduced in another owing to complex edaphoclimatic variations. Therefore, breeding programs are constantly attempting to obtain, through artificial hybridization, novel genotypes with high adaptability and stability potential. The objective of this study was to analyze genetic divergence in sugarcane based on the genotypic values of adaptability and stability. A total of 11 sugarcane genotypes were analyzed for eight agro-industrial traits. The genotypic values of the traits were determined using mixed model methodology, and the genetic divergence based on phenotypic and genotypic values was measured using the Mahalanobis distance. The distance matrices were correlated using the Mantel test, and the genotypes were grouped using the Tocher method. Genetic divergence is more accurate when based on genotypic values free of genotype–environment interactions and will differ from genetic divergence based on phenotypic data, changing the genotype allocations in the groups. The above methodology can be applied to assess genetic divergence to obtain novel sugarcane genotypes with higher productivity that are adapted to intensive agricultural systems using diverse technologies. This methodology can also be tested in other crops to increase accuracy in selecting the parents to be crossed.

Dhiraj Bhandari ◽  
Anita Singh

Background: Mustard represents a rich diversity and widely cultivated in 23 states and union territories of India. However, much of this diversity is concentrated in the Indo-Gangetic plains and the sub-mountain Himalayas. Genetic diversity plays a significant role in plant improvement because a hybrid between the lines of diverse origin usually display a greater heterosis than those between closely related ones which permit the selection of genetically divergent plants to obtain the desirable recombination of segregating generation. Therefore, the present study was undertaken to assess “Genetic Divergence in Leafy Mustard (Brassica juncea. var. rugosa) germplasm grown under Tarai condition of Uttarakhand” and to identify divergent parents for hybridization program, which would provide superior transgressive segregants from collected germplasm. Methods: The present investigation consisted of thirty-two genotypes of leafy mustard and the research was carried out at Vegetable Research Centre (VRC), G.B. Pant University of Agriculture and Technology, Pantnagar, U.S. Nagar (Uttarakhand) in rabi season of 2015-2016. Mustard genotypes were sown in randomized block design with three replications in field and data were observed for seventeen quantitative and qualitative characters. The estimation of genetic divergence was done with the help of Mahalonobis D2 statistic as suggested by Rao (1952). Cluster analysis by Tocher method for all the traits was done. Result: Thirty two germplasm of leafy mustard for different characters and grouped them into six clusters using Mahalanobis D2 statistic. The analysis revealed the maximum inter cluster distance was (20534.12) between cluster V and cluster VI so, we can create variation by inter mating genotypes from these two clusters to each other and the maximum intra cluster distance in cluster III (441.91) with six germplasm. It means we can intermate genotypes of this cluster with each other (2014/MGVAR-2, FS-13-1, FS-13-4, 2014/MGVAR-4, PRHC-12-9-1, PRHC-12-7-2, FS-13-3 and Pusa Sag 1) to create variation in next generations. The clustering pattern could be utilized in selection of parents for crossing and deciding the best cross combinations which may generate the highest possible variability for various traits.

ZooKeys ◽  
2021 ◽  
Vol 1048 ◽  
pp. 79-89
Nikolai L. Orlov ◽  
Oleg A. Ermakov ◽  
Tao Thien Nguyen ◽  
Natalia B. Ananjeva

Based on the combination of molecular and morphological data, we herein report the second known finding of the xenodermid snake species Parafimbrios vietnamensis Ziegler, Ngo, Pham, Nguyen, Le & Nguyen, 2018. The male individual was found in the Yen Bai Province of northwestern Vietnam, more than 200 km from the type locality in Lai Chau Province. Genetic divergence between the newly-collected male and the holotype was low (1.7%), and is in agreement with morphological data that supports that they are conspecific. We give a detailed description of the morphological characters and coloration of the new record and provide an expanded diagnosis of P. vietnamensis. Parafimbrios is a poorly-understood genus, and our recent discovery brings the total number of known specimens of the genus to nine, 1/3 of them having been found in Vietnam (one specimen of P. lao and now two specimens of P. vietnamensis).

Zootaxa ◽  
2021 ◽  
Vol 4999 (1) ◽  
pp. 58-76
Quyen Hanh Do ◽  

A new species of the Cyrtodactylus irregularis group is described from Ninh Thuan Province, southern Vietnam based on molecular divergence and morphological differences. Cyrtodactylus orlovi sp. nov. is distinguished from the remaining Indochinese bent-toed geckos by having the unique combination of the following characters: size medium (SVL 61.0–77.7 mm); dorsal tubercles in 16–20 irregular rows; 36–39 ventral scale rows; precloacal pores absent in females, 5 or 6 in males, in a continuous row; femoral pores absent; 3–8 enlarged femoral scales; postcloacal spurs 1 or 2; lamellae under toe IV 16–19; a continuous neckband; a highly irregular transverse banded dorsal pattern; the absence of transversely enlarged median subcaudal scales. In phylogenetic analyses, the new species was revealed to be the sister taxon to a clade consisting of Cyrtodactylus cattienensis and the most recently described species from Vietnam, C. chungi, with 12.1–12.4% and 11.7 % pairwise genetic divergence from the two species, respectively, based on a fragment of the mitochondrial COI gene.  

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