Levels Of Gene Diversity Research Articles

Genome survey sequencing-based SSR marker development and their validation in Dendrocalamus longispathus.

Bamboo is an important genetic resource in India, supporting rural livelihood and industries. Unfortunately, most Indian bamboo taxa are devoid of basic genomic or marker information required to comprehend the genetic processes for further conservation and management. In this study, we perform genome survey sequencing for development of de novo genomic SSRs in Dendrocalamus longispathus, a socioeconomically important bamboo species of northeast India. Using Illumina platform, 69.49 million raw reads were generated and assembled into 1,145,321 contig with GC content 43% and N50 1228bp. In total, 46,984 microsatellite repeats were mined-out wherein di-nucleotide repeats were most abundant (54.71%) followed by mono- (31.91%) and tri-repeats (9.85%). Overall, AT-rich repeats were predominant in the genome, but GC-rich motifs were more frequent in tri-repeats. Afterwards, 21,596 SSR loci were successfully tagged with the primer pairs, and a subset of 50 were validated through polymerase chain reaction amplification. Of these, 36 SSR loci were successfully amplified, and 16 demonstrated polymorphism. Using 13 polymorphic SSRs, a moderate level of gene diversity (He = 0.480; Ar = 3.52) was recorded in the analysed populations of D. longispathus. Despite the high gene flow (Nm = 4.928) and low genetic differentiation (FST = 0.119), severe inbreeding (FIS = 0.407) was detected. Further, genetic clustering and STRUCTURE analysis revealed that the entire genetic variability is captured under two major gene pools. Conclusively, we present a comprehensive set of novel SSR markers in D. longispathus as well as other taxa of tropical woody bamboos.

Phenotypic and Allelic Distribution of the ABO and Rhesus Blood Groups among students at Hawassa University, Ethiopia

A prior information on the distribution of ABO and Rh groups is important for management of blood bank and transfusion, genetic counseling, anthropological studies, to study the association of blood groups and diet; to investigate the association between blood and diseases. This study aimed to determine the frequency of ABO and Rh bloods and investigate gene diversity at both loci among students in Ethiopia. A descriptive cross-sectional survey was employed involving randomly selected two thousand thirty nine (2039) university students (1054 males and 985 females) with an age range of 18–29 years. Blood groups were determined based on agglutination reaction. The most common blood group was found to be O (42.47%), followed by A (27.86%), B (21.87%), and AB (7.80 %). The frequency of Rh+ and Rh- were 90.88% and 9.12 %, respectively. The combined blood types showed O+, A+, B+ and AB+ were: 38.60 %, 25.20%, 20.10% and 7.00%, respectively. A slightly different distribution pattern of ABO blood group was observed among females from Amhara region (O> B> A>AB). The distribution of ABO phenotypes from Addis Ababa and Amhara did not differ significantly from those expected under the Hardy Weinberg Equilibrium. A high level of gene diversity was observed for both loci. In general, the O blood type is most frequent and followed by A, B and AB. A similar pattern of distribution of the ABO and Rh blood groups was found in male and female study subjects. The present study will generate baseline data that could be used in blood bank management and transfusion, genetic counseling, population genetic and anthropological studies, and for disease management.

Intraspecific differentiation of Allium canadense var. canadense (Amaryllidaceae) across the North American Coastal Plain

AbstractPolyploidy increases genetic variation in plants, leading to adaptations allowing expansion into novel habitats and increased genetic differentiation among populations isolated by barriers to dispersal. Allium canadense var. canadense is a polyploid taxon distributed within the North American Coastal Plain (NACP) biodiversity hotspot. It is the only one of six varieties in a species complex of wild onions native to North America that exhibits bulbils responsible for vegetative reproduction, which may lead to low levels of genetic variation within populations. Despite its threatened/endangered status in the northeast United States and noxious weed listing in Arkansas, USA, little is known about intraspecific differentiation among populations which may be impacted by riverine barriers or seasonal latitudinal gradients. We used sequences of one nuclear (ITS) and two chloroplast (trnL‐F and rpl32‐trnL) DNA regions generated from eight populations in the NACP and one population in Kansas, USA to examine genetic diversity and population structure of A. canadense var. canadense. A total of 12 ITS ribosomal and 10 chloroplast DNA haplotypes were identified. Phylogenetic analyses indicated two major lineages which corresponded to the genealogical relationships identified in the population structure analyses. Significant genetic subdivision among populations was detected across all populations by analysis of molecular variance. Overall, geographic structuring is apparent among populations of A. canadense var. canadense and populations showed moderate levels of gene diversity. These findings are indicative of the complex nature of polyploids and their contribution to genetic diversity among populations with mating systems that might otherwise have no phylogeographic structure.

Genetic diversity and detection of candidate loci associated with alternative morphotypes in a tailed amphibian

Abstract Phenotypic changes in response to environmental cues allow organisms to adapt and enhance their fitness in a given habitat. Despite the significance of phenotypic plasticity in the evolution and ecology of natural populations and the ongoing development of new genomic tools, the underlying genetic basis is still largely unknown. Herein, we examined the underlying mechanisms of genetic and phenotypic divergence among alternative morphs of a natural population of the Greek smooth newt (Lissotriton graecus). The studied population consists of fully aquatic individuals exhibiting facultative paedomorphosis, the retention of larval traits such as gills, and individuals that have passed metamorphosis (paedomorphic vs. metamorphic newts). Based on the single nucleotide polymorphisms (SNPs) obtained, we observed low genetic divergence between the two alternative morphs and similar levels of gene diversity on neutral markers. Despite the observed high gene flow between the morphs, an Fst approach for outliers detected candidate loci putatively associated with the alternative morphs that mapped to four genes. These identified genes have functional roles in metabolic processes that may mediate the persistence of alternative ontogenetic trajectories.

Addressing IGHV Gene Structural Diversity Enhances Immunoglobulin Repertoire Analysis: Lessons From Rhesus Macaque

The accurate germline gene assignment and assessment of somatic hypermutation in antibodies induced by immunization or infection are important in immunological studies. Here, we illustrate issues specific to the construction of comprehensive immunoglobulin (IG) germline gene reference databases for outbred animal species using rhesus macaques, a frequently used non-human primate model, as a model test case. We demonstrate that the genotypic variation found in macaque germline inference studies is reflected in similar levels of gene diversity in genomic assemblies. We show that the high frequency of IG heavy chain V (IGHV) region structural and gene copy number variation between subjects means that individual animals lack genes that are present in other animals. Therefore, gene databases compiled from a single or too few animals will inevitably result in inaccurate gene assignment and erroneous SHM level assessment for those genes it lacks. We demonstrate this by assigning a test macaque IgG library to the KIMDB, a database compiled of germline IGHV sequences from 27 rhesus macaques, and, alternatively, to the IMGT rhesus macaque database, based on IGHV genes inferred primarily from the genomic sequence of the rheMac10 reference assembly, supplemented with 10 genes from the Mmul_051212 assembly. We found that the use of a gene-restricted database led to overestimations of SHM by up to 5% due to misassignments. The principles described in the current study provide a model for the creation of comprehensive immunoglobulin reference databases from outbred species to ensure accurate gene assignment, lineage tracing and SHM calculations.

Genetic Diversity and Structure in a Closed Breeding System of Russian Honey Bees.

High levels of genetic diversity are critical to the success of breeding programs. Russian honey bees are a selected stock that undergoes breeding in a closed block-based mating system. Given its established history, Russian stock has longitudinal measures of genetic integrity (i.e., genetically based stock identity) and diversity. Assessments using genetic stock identification (GSI) have shown that genetic diversity parameters were assessed across breeding blocks for three generations, spanning 6 yr (2014, 2017, and 2020), showing levels comparable to those when the stock was initially released in 2008. Allelic richness (mean number of alleles) and gene diversity levels were consistent over time and among blocks. Blocks were generally not differentiated from one another within each year. However, the 2020 population was distinct when compared with bees sampled in both 2014 and 2017. Genetic distance relationships supported differentiation of the 2020 population by distinct clustering. The patterns observed here are consistent with historical changes made to the breeding program to increase stringency of the selection criteria.

Conservation genomics of an Australian cycad Cycas calcicola, and the Absence of Key Genotypes in Botanic Gardens

Understanding the genetic diversity of wild populations is fundamental to conserving species in-situ and ex-situ. To aid conservation plans and to inform ex-situ conservation, we examined the genetic diversity of the cycad Cycas calcicola (Cycadaceae). Samples were collected from wild populations in the Litchfield National Park and Katherine regions in the Northern Territory, Australia. Additional samples were obtained from botanic garden plants that were originally collected in the Katherine region, Daly River and Spirit Hills in the Northern Territory, Australia. Using RADseq we recovered 2271 informative genome-wide SNPs, revealing low to moderate levels of gene diversity (uHe = 0.037 to 0.135), very low levels of gene flow, and significant levels of inbreeding (mean FIS = 0.491). Population structure and multivariate analysis showed that populations fall into two genetic groups (Katherine vs Litchfield + Daly River + Spirit Hills). Genetic differentiation was twice as high between populations of the Katherine and Litchfield regions (FST ~ 0.1) compared to within these two regions (FST ~ 0.05). Increasing population fragmentation together with high levels of inbreeding and very little gene flow are concerning for the future adaptability of this species. The results indicated that the ex-situ collections (1) had significantly lower genetic diversity than the wild populations, and (2) only partly capture the genetic diversity present, particularly because the Litchfield National Park populations are not represented. We recommend that ex-situ collections be expanded to incorporate the genetic diversity found in Litchfield National Park and to increase the number of representatives from Daly River/Spirit Hills, and that in-situ populations from the Katherine and Greater Litchfield regions be conserved as separate management units.

Genetic Diversity and Population Structure of Endangered Catfish Rita rita (Hamilton, 1822) Revealed by Heterologous DNA Microsatellite Markers

Genetic information is essential for conservation and future aquaculture development of the endangered catfish Rita rita (Hamilton, 1822). Two hundred catfish, R. rita, 50 from four rivers, the Old Brahmaputra, Jamuna, Meghna and Kangsa were collected and analysed to evaluate the genetic diversity and population structure using five microsatellite primers (Cba06-KUL, Cba08-KUL, Cba09-KUL, Phy03-KUL and Phy07-KUL). Four of the five amplified loci were found polymorphic (P95) in all the populations and 46 alleles were recorded with 9 to 14 alleles per locus. Differences were observed in the total number of alleles ranging from 41 to 44, effective number of alleles from 29.96 to 37.46, observed heterozygosity from 0.57 to 0.76, Shannon’s information index from 2.09 to 2.30 and polymorphic information content from 0.84 to 0.88 among the four populations. Results exposed the highest levels of genetic diversity in the Meghna population while the lowest in the Kangsa population of R. rita. All the populations were significantly deviated (P < 0.001) from the Hardy-Weinberg equilibrium for all the loci. Nei’s genetic distance between populations ranged 0.007 to 0.017 with low overall genetic difference FST = 0.011 and high gene flow Nm = 24.333, indicating that R. rita populations were not subdivided. This study revealed a high level of gene diversity with deficiency in genetic heterogeneity in all the populations of R. rita, emphasising natural management, conservation and rehabilitation measures of this species.

Connectivity of Avicennia marina populations within a proposed marine transboundary conservation area between Kenya and Tanzania

Threatened ecosystems such as intertidal mangrove forests often span political boundaries and require cross-border conservation planning initiatives. Population connectivity is key to establish transboundary collaborative actions. In this study, we assessed genetic diversity and connectivity of mangrove populations in a proposed transboundary conservation area (TBCA) between Kenya and Tanzania, where human demography exerts increasing pressure on biodiversity and ecosystem services. East African mangrove ecosystems comprise a complex pattern of estuaries and coastal bays, with Avicennia marina as a major mangrove component. Our main objective was to test a hypothesis of overall migration directionality reflecting regional ocean surface current flows. Fourteen microsatellite markers in 670 A. marina trees revealed no overall significant difference in allele or gene diversity levels between populations but showed an overall effect of geographic distance with a gradient of admixed gene pools. Migration tests and Approximate Bayesian computations supported a customized stepping-stone model of overall south to north migration with bidirectional gene flow and admixture between adjacent bays near the Kenya-Tanzania border. Observed patterns of gene flow suggest an important effect of large rivers and connections via creeks. Our results indicate that relevance for conservation and management of mangroves areas may remain largely within a hydrological connectivity context of each bay, despite prevailing genetic estimates reflecting historically well-connected mangroves between bays. For sustainable management, populations must be considered complementary and not redundant. Hence, transboundary regions must primarily adhere to local contemporary conservation and management, and not solely rely on the assumption of strong regional connectivity built historically.

Metagenomic Analysis Reveals Microbial Community Structure and Metabolic Potential for Nitrogen Acquisition in the Oligotrophic Surface Water of the Indian Ocean.

Despite being the world’s third largest ocean, the Indian Ocean is one of the least studied and understood with respect to microbial diversity as well as biogeochemical and ecological functions. In this study, we investigated the microbial community and its metabolic potential for nitrogen (N) acquisition in the oligotrophic surface waters of the Indian Ocean using a metagenomic approach. Proteobacteria and Cyanobacteria dominated the microbial community with an average 37.85 and 23.56% of relative abundance, respectively, followed by Bacteroidetes (3.73%), Actinobacteria (1.69%), Firmicutes (0.76%), Verrucomicrobia (0.36%), and Planctomycetes (0.31%). Overall, only 24.3% of functional genes were common among all sampling stations indicating a high level of gene diversity. However, the presence of 82.6% common KEGG Orthology (KOs) in all samples showed high functional redundancy across the Indian Ocean. Temperature, phosphate, silicate and pH were important environmental factors regulating the microbial distribution in the Indian Ocean. The cyanobacterial genus Prochlorococcus was abundant with an average 17.4% of relative abundance in the surface waters, and while 54 Prochlorococcus genomes were detected, 53 were grouped mainly within HLII clade. In total, 179 of 234 Prochlorococcus sequences extracted from the global ocean dataset were clustered into HL clades and exhibited less divergence, but 55 sequences of LL clades presented more divergence exhibiting different branch length. The genes encoding enzymes related to ammonia metabolism, such as urease, glutamate dehydrogenase, ammonia transporter, and nitrilase presented higher abundances than the genes involved in inorganic N assimilation in both microbial community and metagenomic Prochlorococcus population. Furthermore, genes associated with dissimilatory nitrate reduction, denitrification, nitrogen fixation, nitrification and anammox were absent in metagenome Prochlorococcus population, i.e., nitrogenase and nitrate reductase. Notably, the de novo biosynthesis pathways of six different amino acids were incomplete in the metagenomic Prochlorococcus population and Prochlorococcus genomes, suggesting compensatory uptake of these amino acids from the environment. These results reveal the features of the taxonomic and functional structure of the Indian Ocean microbiome and their adaptive strategies to ambient N deficiency in the oligotrophic ocean.

Population structure of two morphotypes of Sideroxylon mascatense (A.DC.) T.D.Penn. in Oman

Sideroxylon mascatense (A.DC.) T.D.Penn is a wild fruit-producing plant belonging to the family Sapotaceae and found in North Africa, the Middle East, and parts of Asia. There are two main morphotypes according to existing literature, which are only known to coexist in Oman at high-altitudes, and are known by their vernacular names ‘Būt’ and ‘Hegimt’. For the current study, AFLP fingerprinting was used to analyze the molecular characteristics of these two morphotypes in Oman. The analysis revealed low to moderate levels of gene diversity for S. mascatense with h = 0.169–0.2148 varying by collection site. Genetic diversity of Būt was higher than that of Hegimt at h = 0.2093 and h = 0.1751 respectively. A moderate and significant level of genetic differentiation was found among morphotypes of S. mascatense (Fst = 0.1037 P-value < 0.00000; Nm = 2.16) according to the analysis of molecular variation (AMOVA). The cluster analysis separated the samples tested into two main clades, one with mostly ‘Būt’ and the other with mostly ‘Hegimt’ specimens. The current study, being the first of its type to analyze the molecular characteristics of S. mascatense, builds a foundation for future work on this unique mountain species that spans the arid regions of Asia and Africa.

No impact of a short-term climatic \u201cEl Ni\xf1o\u201d fluctuation on gut microbial diversity in populations of the Gal\xe1pagos marine iguana (Amblyrhynchus cristatus)

Gut microorganisms are crucial for many biological functions playing a pivotal role in the host’s well-being. We studied gut bacterial community structure of marine iguana populations across the Galápagos archipelago. Marine iguanas depend heavily on their specialized gut microbiome for the digestion of dietary algae, a resource whose growth was strongly reduced by severe “El Niño”-related climatic fluctuations in 2015/2016. As a consequence, marine iguana populations showed signs of starvation as expressed by a poor body condition. Body condition indices (BCI) varied between island populations indicating that food resources (i.e., algae) are affected differently across the archipelago during ‘El Niño’ events. Though this event impacted food availability for marine iguanas, we found that reductions in body condition due to “El Niño”-related starvation did not result in differences in bacterial gut community structure. Species richness of gut microorganisms was instead correlated with levels of neutral genetic diversity in the distinct host populations. Our data suggest that marine iguana populations with a higher level of gene diversity and allelic richness may harbor a more diverse gut microbiome than those populations with lower genetic diversity. Since low values of these diversity parameters usually correlate with small census and effective population sizes, we use our results to propose a novel hypothesis according to which small and genetically less diverse host populations might be characterized by less diverse microbiomes. Whether such genetically depauperate populations may experience additional threats from reduced dietary flexibility due to a limited intestinal microbiome is currently unclear and calls for further investigation.

Structure and genetic diversity of Theobroma speciosum (Malvaceae) and implications for Brazilian Amazon conservation

Abstract The genetic diversity of Theobroma speciosum is important because its use in breeding programs, once the species is closely related to species of great economic value such as Theobroma cacao (cocoa) and Theobroma grandiflorum (cupuaçu). Thus, the objective of this work is to characterize the intra and interpopulational genetic diversity of Theobroma speciosum in natural populations in the Brazilian Amazon. Ninety individuals of T. speciosum from four populations localized in different states of legal Amazon were selected and genotyped. The data were obtained by fluorescence microsatellite analysis and the number of alleles, number of private alleles, fixation index, observed and expected heterozygosity were analyzed. Bayesian analysis, AMOVA and PCOa were used to reveal the molecular genetic structure of the populations, using the programs Structure and GenAIEx 6.5, respectively. All populations studied present great levels of gene diversity, although, there was a greater similarity among the AUR, API and MAC populations, while RBC population presented higher heterozygosity and less inbreeding than the others, becoming a possible refuge area in the Amazon, and the most important population for T. speciosum conservation.

Assessment of genetic diversity and phylogenetic relationship among grouper species Epinephelus spp. from the Saudi waters of the Arabian Gulf.

Understanding of fish genetic characterization plays a vital role in the conservation and utilization of fish genetic resources of grouper species. The present study was carried out to assess the genetic diversity and phylogenetic relationships in five grouper species, Epinephelus spp. from eastern Saudi Arabian coast using two molecular marker systems, inter simple sequence repeat (ISSR) and microsatellite (SSR) markers. In total, 219 individuals grouper specimens (Epinephelus tauvina, E. coioides, E. bleekeri, E. malabaricus, and E. areolatus) were genotyped with 10 ISSR and 11 SSR selected primers. The ISSR produced 94 DNA fragments, of which 44 were polymorphic with an average of 2.13 fragment per primer. While SSR primers generated 107 alleles, all of them were polymorphic with an average 9.72 per primer. ISSR and SSR techniques demonstrated a high level of gene diversity and genetic distances illustrated by UPGMA dendrograms among the grouper species. The results proved that the SSR markers were highly informative and efficient in detecting genetic variability and relationships of the Epinephelus spp.

Genetic variation in common bean (Phaseolus vulgaris L.) using seed protein markers

Abstract The genetic diversity of common bean accessions were assessed using seed storage protein markers. At regional level, accessions from the two major growing regions showed the highest level of gene diversity (H = 0.322, I = 0.485, and H = 0.312, I = 0.473), which can be exploited for the future improvement of the crop. Based on phaseolin, the major storage protein in common bean, the majority of the accessions (86%) were grouped under Mesoamerican gene pool. Seed proteins were also used to differentiate various Phaseolus species, indicating the usefulness of seed storage proteins in species identification in this genus.

Genetic diversity assessment of Hemibagrus nemurus from rivers in Java Island, Indonesia using COI gene

Abstract. Nuryanto A, Komalawati N, Sugiharto. 2019. Genetic diversity assessment of Hemibagrus nemurus from rivers in Java Island, Indonesia using COI gene. Biodiversitas 20: 2707-2717. Green catfish (Hemibagrus nemurus) is a popular freshwater fish that highly exploited in almost all the rivers in Java Island. The exploited population tends to have low genetic diversity. Meanwhile, separated populations might lead to a genetic difference among the river populations. This study aims to investigate the genetic diversity and population variation of H. nemurus collected at eleven rivers across Java Island. The analysis based on 465 bp fragment of the cytochrome c oxidase 1 gene from 140 individuals. Analysis of overall populations proved that H. nemurus had a high gene diversity (h= 0.935±0.016) and nucleotide diversity (π = 0.073±0.036). Within population analysis also showed that H. nemurus populations showed high levels of gene diversity (h= 0.338±0.128 to 1.000±0.022) and nucleotide diversity (π =0.001±0.001 to 0.071±0.038). Those diversity values indicated that H. nemurus had high level of genetic diversity, except for the Citanduy population. Population comparison showed that significant genetic differences observed among populations (p= 0.000 for both variance component and Fst-value). However, pairwise comparison analysis indicated complex pattern of population differentiation. The high genetic diversity and complex pattern of population differentiation have important implication for H. nemurus conservation in Java Island.

The largest fish in the world's biggest river: Genetic connectivity and conservation of Arapaima gigas in the Amazon and Araguaia-Tocantins drainages.

Arapaima, pirarucu or paiche (Arapaima gigas) is one of the largest freshwater fish in the world, and has a long history of commercial exploitation in the Amazon region. To estimate levels of genetic variability and historical and recent connectivity in Arapaima, we examined variation in eleven microsatellite DNA markers in individuals from 22 localities in Brazil, Colombia, and Peru. The results of analysis of molecular variance, Bayesian clustering and discriminant analysis of principal components showed that Arapaima in our samples represents two major populations, one in the Amazonas and one in the Araguaia-Tocantins River basins. The Amazonas population is further structured by isolation-by-distance with the hydrologically largely unconnected Amapá locality representing the eastern-most extreme of this continuum; gene flow predominates at distances of less than 1500 km with localities separated by over 2000 km dominated by genetic drift and effectively forming different populations. We saw no evidence of multiple species of Arapaima in the Amazonas basin, and analysis of pairwise genetic divergence (FST) with Mantel tests and correlograms indicated that this largest population exhibits a large-scale pattern of isolation-by-distance, with which results from MIGRATE-N agreed. The degree and significance of genetic divergence indicates that most sampled localities represent demographically independent sub-populations, although we did identify several recent migration events between both proximal and more distant localities. The levels of genetic diversity were heterogeneous across sites, including low genetic diversity, effective population sizes, and evidence of genetic bottlenecks in several places. On average the levels of gene diversity and rarefied allelic richness were higher for localities along the Amazonas mainstem than in the tributaries, despite these being the areas of highest fishing pressure, while the lowest values were found in tributary headwaters, where landscape modification is a significant threat. We recommend that managers consider the regional and local threats to these populations and tailor strategies accordingly, strategies which should ensure the ability of young A. gigas to disperse through floodplain corridors to maintain genetic diversity among otherwise sedentary adult sub-populations.

Intraspecific genetic variability, differentiation and evolutionary relationships revealed through microsatellite loci in seven economically important Calamus species

Population density, species richness and critical population parameters are crucial in determining the levels of gene diversity in dioecious species of the genus Calamus. The extent of intraspecific and intrageneric genetic variability in Calamus from the southern Western Ghats of India was studied using 26 microsatellite markers by sampling 227 individuals belonging to seven economically important species. The heterozygosity of microsatellite loci ranged from zero to 0.78. Average gene diversity within species was 0.13; in all species it was 0.18 and amongst species was 0.06. The Shannon Information Index was the lowest for Calamus metzianus (0.11), whereas it ranged from 0.16 to 0.26 for other species. The expected heterozygosity varied from 0.08 to 0.18. Calamus hookerianus and Calamu travancoricus showed the highest genetic differentiation (44%) revealed through Fst values, whereas the lowest (22%) was observed between Calamus gamblei and Calamu thwaitesii. Population structuring and phylogenetic analysis differentiated the seven species. Due to overexploitation and loss of rare alleles, small populations could lead to fertilization between closely related individuals, resulting in inbreeding and increasing the risk of extinction. This could be important for species such as C. metzianus where allelic polymorphism was 23%, whereas for all other species it was 38% to 46%. Genetic diversity “micro-hotspots” were identified from the protected area network of the southern and central Western Ghats with highest observed heterozygosity. Four micro-hotspots from the Agasthyamalai Biosphere Reserve and the Pushpagiri Wildlife Sanctuary may be possible for long-term conservation programs. The findings of this study lay a strong foundation for strengthening protected area networks, especially areas with intermediate levels of disturbance.

Genetic Diversity and Population Structure in Upland Rice (Oryza sativa L.) of Mizoram, North East India as Revealed by Morphological, Biochemical and Molecular Markers.

Upland rice landraces from different villages of Mizoram, Northeast India were analyzed for seed morphology, amylose content, aromatic characteristic, seed storage protein profiling and genetic diversity. Results revealed variation in grain length, width, weight and shape. Protein profiling showed polypeptide bands ranging from 7 to 10 with similarity coefficient from 0.556 to 1.000 in the studied populations. Population genetic analysis using simple sequence repeats markers revealed a total of 63 alleles with a high level of gene diversity at 0.6468. High values of Fst and PIC estimates were found at 0.7239 and 0.5984 respectively. The Biruchuk population was found to be the most genetically diverse cultivar and least gene diversity was found in Tuikuk buh. The UPGMA trees based on seed morphology, seed storage protein profiling and simple sequence repeats diversity showed the grouping of rice cultivars into three clusters which were further supported by model-based STRUCTURE analysis. This finding is the first-hand report in upland rice of the state and can be useful for selecting suitable rice lines for prebreeding and germplasm conservation of indigenous hill rice cultivars of Mizoram.

Effects of the Tanaka Line on the genetic structure of Bombax ceiba (Malvaceae) in dry-hot valley areas of southwest China.

Southwest China is an important biodiversity hotspot. The interactions among the complex topography, climate change, and ecological factors in the dry‐hot valley areas in southwest China may have profoundly affected the genetic structure of plant species in this region. In this study, we determined the effects of the Tanaka Line on genetic variation in the wild Bombax ceiba tree in southwest China. We sampled 224 individuals from 17 populations throughout the dry‐hot valley regions. Six polymorphic expressed sequence tag–simple sequence repeat primers were employed to sequence the PCR products using the first‐generation Sanger technique. The analysis based on population genetics suggested that B. ceiba exhibited a high level of gene diversity (H E: 0.2377–0.4775; I: 0.3997–0.7848). The 17 populations were divided into two groups by cluster analysis, which corresponded to geographic characters on each side of the Tanaka Line. In addition, a Mantel test indicated that the phylogeographic structure among the populations could be fitted to the isolation‐by‐distance model (r 2 = .2553, p < .001). A barrier test indicated that there were obstacles among populations and between the two groups due to complex terrain isolation and geographic heterogeneity. We inferred that the Tanaka Line might have promoted the intraspecific phylogeographic subdivision and divergence of B. ceiba. These results provide new insights into the effects of the Tanaka Line on genetic isolation and population differentiation of plant species in southwest China.