Center Of Origin Research Articles

Diversification and subspecies patterning of the goitered gazelle (Gazella subgutturosa) in Iran.

Goitered gazelles, Gazella subgutturosa, exist in arid and semiarid regions of Asia from the Middle to the Far East. Although large populations were present over a vast area until recently, a decline of the population as a result of hunting, poaching, and habitat loss led to the IUCN classification of G. subgutturosa as “vulnerable." We examined genetic diversity, structure, and phylogeny of G. subgutturosa using mitochondrial cytochrome b sequences from 18 geographically distant populations in Iran. The median‐joining network of cyt b haplotypes indicated that three clades of goitered gazelles can be distinguished: a Middle Eastern clade west of the Zagros Mountains (and connected to populations in Turkey and Iraq), a Central Iranian clade (with connection to Azerbaijan), and an Asiatic clade in northeastern Iran (with connection to Turkmenistan, Uzbekistan, and other Asian countries as far as northeastern China and Mongolia). Based on our results, we argue that Iran is the center of diversification of goitered gazelles, due to the presence of large mountain ranges and deserts that lead to the separation of populations. In accordance with previous morphological studies, we identified the Asiatic clade as the subspecies G. s. yarkandensis, and the other two clades as the nominate form G. s. subgutturosa. The new genetic information for goitered gazelles in Iran provides the basis for future national conservation programs of this species.

<p><strong>An assessment of the local endemism of flowering plants in the northern Western Ghats and Konkan regions of India: checklist, habitat characteristics, distribution, and conservation</strong></p>

The Western Ghats of India support a significant amount of biodiversity despite heavy habitat loss. The northern part of this biodiversity hot-spot, along with Konkan, is considerably different from its southern and central counterparts on account of lesser precipitation and extended dry season. Though this region has been floristically surveyed well, there was a long need for a synthesis on local endemism of the flowering plants. Therefore, the present work was undertaken to produce an updated list of the local endemic plant species of the region with an analysis of habitat characteristics and their survival strategies. An extensive review of literature, herbarium records, and field studies yielded a checklist of 181 taxa including four monospecific genera which were examined for their distribution across their latitudinal spread and habitat specificity. A majority of the endemics are therophytes with their predominance, especially on rock outcrops. Northern Western Ghats seems to be the center of rapid diversification of certain herbaceous endemic genera like Ceropegia, Glyphochloa, Dipcadi, Eriocaulon and a few others. Despite being declared as a biodiversity hot-spot and having a higher concentration of endemic taxa, the region is underrepresented in global IUCN threat status assessments. The implication of effective conservation measures is necessary and the data presented in the manuscript can be used as a proxy for conservation planning.

DIVERSIDAD GENÉTICA EN POBLACIONES DE RAZAS MEXICANAS DE MAÍZ

El maíz (Zea mays L.) de México presenta amplia diversidad debido a que este país es considerado como centro de origen, domesticación y diversificación de esta especie, y si bien existen estudios al respecto, la gran abundancia de tipos hace pertinente profundizar en su análisis. El presente estudio tuvo como objetivo evaluar la diversidad genética inter e intra-poblacional de 25 poblaciones de razas de maíz con 10 marcadores SSR. La primera coordenada principal explicó 42.11 % y la segunda 18.18 % de la variación total. Se encontró un promedio de 2.6 alelos por locus y un valor de diversidad génica de 0.44. El estadístico FST (0.427) indicó una alta diferenciación genética entre las razas de maíz (Zea mays L.). Las razas Serrano de Jalisco y Tabloncillo mostraron los índices más altos de diversidad génica (0.53). La variación inter-poblacional fue del 43 %. Las razas destinadas para usos especiales y con distribución geográfica limitada, como Comiteco (0.33) y Chalqueño (0.30), presentaron los niveles más bajos de diversidad y a su vez exhibieron graves procesos de endogamia (FIT = 0.618) y deriva genética.

Allopolyploidy and genomic differentiation in holocentric species of the Eleocharis montana complex (Cyperaceae)

Polyploidy and hybridization are key events in plant evolution. Due to these events, complexes of species can be formed. Dysploidy, a frequent chromosome change in holocentric organisms, may add some difficulties to species delimitation, especially in Cyperaceae. The Eleocharis montana complex is known for its members with overlapping morpho-anatomical features and unclear circumscription. To understand its biological history, several tools were used to investigate different American populations, including morpho-anatomical analysis, genome size estimates, cytogenomic analysis, molecular marker characterization, and genomic in situ hybridization (GISH). Despite overlapping morphological features, it was possible to separate two groups, the first containing E. parodii and E. subarticulata, presenting diploid and dysploid karyotypes, respectively, and small DNA C-values. The second contained E. elegans, E. contracta, and E. montana, with large genomes created by polyploidy. All analyses suggest that E. montana with 2n = 40 is a cytotype of E. contracta with 2n = 20, and both evolved from a natural hybridization involving E. parodii (2n = 10) and a second progenitor that is yet unknown. Furthermore, the GISH results indicated that E. parodii may be an ancestor of E. elegans. All species occur in the probable center of diversification in Austral South America, where the hybridization zone is identified. Fieldwork and information obtained from herbaria indicate that diploid and dysploid species (E. subarticulata and E. parodii) do not occur beyond the center of diversification. However, E. elegans and specially E. montana occur more widely, occupying different flooded environments and landscapes.

Introgression Among Cultivated and Wild Grapevine in Tuscany.

Wild grapevine, Vitis vinifera L. subsp. sylvestris (Gmelin, Hegi) is spontaneous to Europe and common in Tuscany. In this study, wild grapevines were identified in 22 populations from eight locations in Tuscan Maremma (Grosseto and Siena province). The plants were propagated by cuttings, collected in a vineyard, genotyped by nuclear simple sequence repeats (SSRs), chloroplast SSRs and single nucleotide polymorphisms (SNPs), and compared to locally cultivated varieties (Vitis vinifera L. subsp. sativa) and to non-vinifera and non-vitis genotypes. The identity analysis revealed that some individuals were redundant genotypes, suggesting natural vegetative propagation. In addition, four of the supposed V.v. sylvestris were in fact naturalized V.v. sativa. The majority of putative sylvestris genotypes had chlorotype A, while the remainder had chlorotype D, as the majority of Vitis vinifera subsp. sativa cultivated in Italy. Some of the recovered sylvestris genotypes appeared to be natural crosses with cultivated grapevine varieties in Tuscany, and their chlorotype suggests a higher pollen flow from sativa to the sylvestris genotypes than in the opposite direction. In addition, other genotypes appeared to be crosses within sylvestris, sylvestris-sativa or sylvestris-sylvestris siblings, or equivalent relationships. These relationships suggest a noticeably level of sexual reproductive activities among sylvestris and sylvestris-sativa genotypes. A cluster and structure analysis clearly differentiated the true sylvestris from the sativa, and the non-vinifera or non-vitis genotypes, and also highlighted a possible introgression of sylvestris into some Italian and French cultivated varieties. The results therefore suggest that, in addition to the primary ancient center of domestication from the Near East to Central Asia, the introgression among cultivated and wild grapevine occurred in other centers of diversification along the migration routes, contributing to the domestication processes, and suggesting that these processes are still ongoing despite the reduction in populations of sylvestris. The results also highlight that the GrapeReSeq 18K Vitis genotyping chip are suitable for non-vitis genotyping and that the range of SNPs heterozygosity in sylvestris appears to be up to 6% less and does not overlap the heterozygosity range of sativa genotypes.

What should we call the Levant mole? Unravelling the systematics and demography of Talpa levantis Thomas, 1906 sensu lato (Mammalia: Talpidae)

Turkey hosts 5 of the 11 species of Talpa described to date and Anatolia, in particular, appears to be an important centre of diversity for this genus. Of these taxa, the Levant mole, Talpa levantis Thomas, 1906 has been found to consist of two genetically divergent sublineages, which may represent separate species. Here, we use a combination of mitochondrial and nuclear DNA sequences from specimens of T. levantis s.lat., collected across the species’ geographical range, to explore the systematics and demographic history of Levant moles. Both mitochondrial and nuclear markers confirm the existence of distinct eastern and western sublineages, which apparently diverged from each other in the early Pleistocene. Given the degree of cytochrome-b divergence between these (7.28%), we consider them to represent independent cryptic species. By including topotypic specimens of T. levantis s. str. in our study, we are able to show that this name applies to the western sublineage, distributed across most of the Anatolian Black Sea coastal region, from the vicinity of Trabzon in the east, westwards to Marmara. The earliest name available for the eastern taxon, found in Transcaucasia and adjacent parts of north-eastern Anatolia, is T. transcaucasica Dahl, 1944. Cytochrome-b haplotype diversity in T. levantis is relatively high and demographic analyses suggest that the species may have survived in multiple, separate, refugial areas during the Pleistocene. Our work brings the total number of named mole species recognized in Turkey to six, emphasising the importance of this region as a global centre of mole diversification.

Molecular phylogeny and species delimitation of Amiota alboguttata and Amiota basdeni species groups (Diptera: Drosophilidae) from East Asia

Abstract Phylogenetic relationships of the two largest species groups in the genus Amiota [the Amiota alboguttata group (29 known and six new species) and the Amiota basdeni group (17 known and three new species)] were reconstructed using two mitochondrial gene sequences (COI and ND2). The paraphyly of the A. alboguttata group was identified based on molecular evidence. The monophyletic A. basdeni group is found to be nested in the A. alboguttata group, rendering the latter paraphyletic. Automatic barcode gap discovery and Bayesian phylogenetics and phylogeography methods were used to assess species limits of the A. alboguttata and A. basdeni groups. The results indicate that most analysed species could be delimited clearly, including nine new species (Amiota beama sp. nov., Amiota cyclophylla sp. nov., Amiota flormontana sp. nov., Amiota obtusa sp. nov., Amiota planiceps sp. nov., Amiota scrobicula sp. nov., Amiota jianjuni sp. nov., Amiota tentacula sp. nov. and Amiota xinglaii sp. nov.), except for some closely related morphospecies. Furthermore, based on the highly biased distributions of these two groups, southwestern China is hypothesized to be a possible centre of origin and diversification for Amiota in East Asia.

Global biogeographic synthesis and priority conservation regions of the relict tree family Juglandaceae

AbstractAimTo establish a complete database of Juglandaceae at a spatiotemporal scale and develop a phylogeographic framework with which to elucidate the distributional patterns, diversity patterns, origins, evolution, and conservation priority regions of this family.LocationWorldwide.TaxonWalnut family (Juglandaceae).MethodsData on the distribution of all the extant and fossil species of Juglandaceae were collected, followed by analyses of its latitudinal distribution, elevational distribution, and species and generic diversity. Furthermore, based on all genera and 87% of the species, we reconstructed phylogenetic relationships, estimated divergence times, calculated phylogenetic diversity and inferred ancestral distributions.ResultsExtant Juglandaceae (10 genera and 60 species) are mainly distributed in eastern Asia and North America (principally between 20 and 40°N). Tropical Juglandaceae mainly inhabit mountainous areas higher than 1,000 m, especially in the New World. Southwest China and northern Vietnam are characterized by high species, generic and phylogenetic diversity. The United States of America has only high species diversity. The area of origin of Juglandaceae was North America and Europe in the early Eocene, and its widespread dispersal mainly occurred between 13 and 26 Ma.Main conclusionsThe members of Juglandaceae inhabit areas with temperate climatic conditions. The diversification centre has shifted intercontinentally from North America and Europe to Southwest China and northern Vietnam, which are identified as conservation priority regions. The high‐latitude cooling during the Oligocene followed by a long‐term stable warmer climate in the early and middle Miocene drove the southward translocation of the family.

Vavilov Centers or Vavilov Cultures? Evidence for the Law of Homologous Series in World System Evolution

Vavilov Centers or Vavilov Cultures? Evidence for the Law of Homologous Series in World System Evolution

VALIDACIÓN EMPÍRICA DE LA TEORÍA MULTICÉNTRICA DEL ORIGEN Y DIVERSIDAD DEL MAÍZ EN MÉXICO

Mesoamerica is considered as the center of origin and diversity of maize (Zea mays L.). The multicentric theory on the origin and diversity of maize defines five centers of origin-domestication, from which four macro regions or primary centers of diversification of this cereal were conformed, from which the different races and the concentration of diversity emerged. A center of genetic diversity is defined as the geographical area where there is morphological, genetic diversity, or both, for a certain species, characterized by harboring populations of wild relatives and constituting a genetic reserve. The objective of this study was to empirically validate the geographic regions of Mexico that conform to the definition of a center of genetic diversity for maize. Spatial analysis was used to examine the diversity and distribution of 24,126 accessions of native maize and 1,106 records of wild relatives (Teosinte: 692 and Tripsacum: 414) collected during the period 1926 2014, available at germplasm banks and herbaria of national and international agricultural research and education institutions located in Mexico and, through the use of geographic information systems and modeling. In accordance with the criteria and definitions considered in the multicentric theory on maize origin and diversity, 19 geographic regions were empirically defined and validated to be considered as centers of genetic diversity of maize native to Mexico.

<p><strong>New species of <em>Archisargus </em>from the Middle Jurassic Daohugou of Northeastern China (Diptera: Brachycera: Archisargidae)</strong></p>

Archisargidae, an extinct family of the suborder Brachycera, are traditionally attributed to the infraorder Stratiomyomorpha (Oberprieler & Yeates, 2012). The type genus, Archisargus Rohdendorf, 1938, is a small group including only four species from two well-known localities, the Karatau Formation of Kazakhstan and the Jiulongshan Formation of China. Rohdendorf (1938) erected the genus based on the species Archisargus pulcher from the Karatau Formation of Kazakhstan, and assigned it to Stratiomyidae. Hennig (1954) questioned Rohdendorf’s assignment and pointed out that the characters of the Stratiomyidae were absent, but he didn’t propose an appropriate placement for this genus. Rohdendorf (1962) reconsidered the systematic position of the genus and established the new family Archisargidae based on the genus. In fact, the description of the Archisargus was not informative due to the incomplete preservation of the type specimen (only Sc and R were mentioned) (Rohdendorf, 1938). Mostovski (1997) re-described the type specimen of Archisargus pulcher, clarified the status of the genus, and described a second species, Archisargus maximus, which was also from Karatau, Kazakhstan. A decade later, Zhang et al. (2007) described two older species from the Middle Jurassic of Daohugou, China. The Daohugou locality is well-known for its diverse fossil insects, representing an important diversification center of insects during the Mesozoic Era (Ren et al., 2009; Wang et al., 2010, 2012; Gao et al., 2012; Gu et al., 2012; Meng et al., 2017; Ren et al., 2019). Herein, we describe a new species, Archisargus aequinervus sp. nov., from this locality. Additionally, a key to species of the genus is provided.

Phylogeny and species delimitation of Strobilomyces (Boletaceae), with an emphasis on the Asian species.

Strobilomyces is broadly distributed geographically and serves an important ecological function. However, it has been difficult to delimit species within the genus, primarily due to developmental variations and phenotypic plasticity. To elucidate phylogenetic relationships among species within the genus and to understand its species diversity, especially in Asia, materials of the genus collected from five continents (Africa, Asia, Australia, Europe, and North/Central America) were investigated. The phylogeny of Strobilomyces was reconstructed based on nucleotide sequences of four genes coding for: the largest and the second largest subunits of the RNA polymerase II (RPB1 and RPB2); the translation elongation factor subunit 1-α (TEF1); and the mitochondrial cytochrome oxidase subunit 3 (COX3). The combined results based on molecular phylogenetics, morphological characters, host tree associations, and geographical distribution patterns support a new classification consisting of two sections, sect. Strobilomyces and sect. Echinati. Using the genealogical concordance phylogenetic species recognition (GCPSR) approach, at least 33 phylogenetic species in Asia can be delimited, all of which are supported by morphological features, and five phylogenetic species remain to be described. The mountainous region of Southwest China is especially special, containing at least 21 species and likely represents a centre of diversification. We further compared our specimens with the type specimens of 25 species of Strobilomyces. Our comparisons suggest that, there are a total of 31 distinct species, while S. sanmingensis, S. verruculosus, S. subnigricans, and S. zangii/S. areolatus, are synonyms of S. mirandus, S. giganteus, S. alpinus and S. seminudus, respectively. Eight new species, namely, S. albidus, S. anthracinus, S. calidus, S. cingulatus, S. densisquamosus, S. douformis, S. microreticulatus and S. pinophilus, are described. A dichotomous key to the Asian Strobilomyces species is provided.

Review on Heterosis and Combining Ability Study for Yield and Morphological Characters of Coffee (Coffea arabica L) in Ethiopia

Ethiopia is both the center of origin and diversification of Coffee arabica. Despite the existence of high genetic diversity in coffee population that provides immense opportunities for improvement program, shortage of improved varieties (pure line and hybrid varieties) is the major one. It is obvious that research work carried out so far on coffee genetics and breeding was not adequate to address these diverse agro-ecologies of the country. Heterosis and combining ability studies are some of the basic breeding tools to address such problems. Some studies had been focused on assessment of heterosis and combining ability analysis for yield and morphological characters of coffee in Ethiopia and the presence of heterosis was reported in crosses of selected indigenous C. arabica L. varieties in Ethiopia under different set of studies mainly due to presence of diverse parental lines. These results clearly suggested that the possibility to bring significant coffee improvement through heterosis and combining ability analysis. Therefore, continuous crossing program should be required to acquire many more cross combinations for intensive and extensive evaluation to develop better performing and high yielding hybrids for Ethiopian origin coffee. Keywords: Coffee Arabica, morphological traits, yield, Heterosis and combining ability DOI : 10.7176/JEES/9-12-03 Publication date: December 31 st 2019

The complex evolutionary history of apricots: Species divergence, gene flow and multiple domestication events.

Domestication is an excellent model to study diversification and this evolutionary process can be different in perennial plants, such as fruit trees, compared to annual crops. Here, we inferred the history of wild apricot species divergence and of apricot domestication history across Eurasia, with a special focus on Central and Eastern Asia, based on microsatellite markers and approximate Bayesian computation. We significantly extended our previous sampling of apricots in Europe and Central Asia towards Eastern Asia, resulting in a total sample of 271 cultivated samples and 306 wild apricots across Eurasia, mainly Prunus armeniaca and Prunus sibirica, with some Prunus mume and Prunus mandshurica. We recovered wild Chinese species as genetically differentiated clusters, with P.sibirica being divided into two clusters, one possibly resulting from hybridization with P.armeniaca. Central Asia also appeared as a diversification centre of wild apricots. We further revealed at least three domestication events, without bottlenecks, that gave rise to European, Southern Central Asian and Chinese cultivated apricots, with ancient gene flow among them. The domestication event in China possibly resulted from ancient hybridization between wild populations from Central and Eastern Asia. We also detected extensive footprints of recent admixture in all groups of cultivated apricots. Our results thus show that apricot is an excellent model for studying speciation and domestication in long-lived perennial fruit trees.

The other side of the Sahulian coin: biogeography and evolution of Melanesian forest dragons (Agamidae)

AbstractNew Guinea has been considered both as a refuge for mesic rainforest-associated lineages that contracted in response to the late Cenozoic aridification of Australia and as a centre of biotic diversification and radiation since the mid-Miocene or earlier. Here, we estimate the diversity and a phylogeny for the Australo-Papuan forest dragons (Sauria: Agamidae; ~20 species) in order to examine the following: (1) whether New Guinea and/or proto-Papuan Islands may have been a biogeographical refuge or a source for diversity in Australia; (2) whether mesic rainforest environments are ancestral to the entire radiation, as may be predicted by the New Guinea refuge hypothesis; and (3) more broadly, how agamid ecological diversity varies across the contrasting environments of Australia and New Guinea. Patterns of lineage distribution and diversity suggest that extinction in Australia, and colonization and radiation on proto-Papuan islands, have both shaped the extant diversity and distribution of forest dragons since the mid-Miocene. The ancestral biome for all Australo-Papuan agamids is ambiguous. Both rainforest and arid-adapted radiations probably started in the early Miocene. However, despite deep-lineage diversity in New Guinea rainforest habitats, overall species and ecological diversity is low when compared with more arid areas, with terrestrial taxa being strikingly absent.

RED BOWL-SHAPED FLOWERS: CONVERGENCE FOR BEETLE POLLINATION IN THE MEDITERRANEAN REGION

ABSTRACT Anemone coronaria, Papaver rhoeas, Ranunculus asiaticus, and Tulipa agenensis are pollinated primarily by scarabaeid beetles (Amphicoma, Glaphyridae) and secondarily by bees (Lasioglossum marginatum Br., Halictidae, and Synhalonia plumigera Kohl, Anthophoridae). The four plant species have large bowl-shaped flowers which are orange-red in color with a black center, radial symmetry, weak scent (to humans), and filamentous stamens. It is suggested that there is a convergent evolution of red bowl-shaped flowers in the East Mediterranean region, concordant with a center of diversity in the genus Amphicoma. The floral phenology of these “Poppy guild” species correlated positively with the amount of edible pollen produced by each of them and with the visiting frequencies of their pollinators. Field experiments showed that Amphicoma beetles also preferred red, odorless flower models over odorless models of different colors, and models with a dark center over plain red ones. This evidence extends the cla...

<p><strong>Phylogenetic relationships of <em>Echeveria </em>(Crassulaceae) and related genera from Mexico, based on three DNA barcoding loci</strong></p>

Mexico is considered as diversification and endemism center of the genus Echeveria. Previous tree inference studies have shown the genus to be non-monophyletic in relation to other genera, but sampling for Echeveria has been poor, and has not allowed to understand the relationships within the genus. In this work, Bayesian and maximum likelihood phylogenetic analysis were performed, using a combined standard DNA barcoding loci matrix (rbcL, matK and ITS2) and GenBank ITS2 accessions for Graptopetalum, some Sedum and few Echeveria taxa. The selection of taxa encompasses all current infrageneric categories of the genus Echeveria, as well as species from genera previously associated with it. The inferred consensus trees suggested that Echeveria is paraphyletic. Instead, four main clades were retrieved within the “Echeveria group”: Clade I includes exclusively Pachyphytum species. Clade II is formed by the majority of series Urbiniae; Clade III encompasses series Chloranthae, Ciliatae, Echeveria, Mucronatae, Nudae, Racemosae, Thyrsiflorae, Pachyphytum cuicatecananum and Thompsonella; Clade IV contains series Angulatae, Gibbiflorae, Occidentales, Pruinosae, Secundae, some Urbiniae species, Valvatae. genera Cremnophila, Graptopetalum and Reidmorania. Pachyphytum and Thompsonella were retrieved as monophyletic groups, but the first outside Echeveria while the latter inside. Results of our study suggest that Echeveria and the Echeveria Group require a redefinition.

Molecular characterisation of some stubby root nematodes (Nematoda: Trichodoridae) from the USA and other countries

Summary The stubby root nematodes are world-wide distributed polyphagous root ectoparasites and can cause damage to a wide range of crops and natural vegetation. In this study, 22 valid and putative species of stubby root nematodes were identified in 37 samples collected in Malaysia, Mexico, Russia, and the USA (California, Florida, Minnesota and Nevada). The analysis of 58 new sequences of the D2-D3 expansion fragments of 28S rRNA gene revealed the following species: Nanidorus minor from California, Florida and Mexico, N. renifer from Florida, two unidentified Nanidorus species from California and Malaysia, respectively, Paratrichodorus allius from Florida and Minnesota, P. pachydermus and Paratrichodorus sp. from Russia, Trichodorus californicus, T. intermedius, and T. obscurus from California, T. obtusus from Florida, eight unidentified Trichodorus species from California, one unidentified Trichodorus species from Nevada, and two unidentified species of stubby root nematodes, one of Trichodorus and another undetermined species from Mexico. Molecular characterisation of T. californicus, T. intermedius and T. obscurus is given for the first time. The phylogenetic tree reconstructed from the analysis of 108 D2-D3 of 28S rRNA gene sequences of 58 valid and putative species of the stubby root nematodes contained five major clades: i) Trichodorus from Europe, Asia and North America; ii) Nanidorus and Trichodorus from Asia; iii) Trichodorus from California; iv) Paratrichodorus from several distant geographical regions; and v) Monotrichodorus from Central and South America. It has been hypothesised that the California Floristic Province is one of the centres of origin and diversification of stubby root nematodes. There is no information on the economic importance of the stubby root nematode species found in California and Mexico. The confirmation of the occurrence of N. renifer and P. allius in Florida should be of concern for the blueberry and potato industries in the state.

Water Quality and Macroinvertebrate Community in Dryland Streams: The Case of the Tehuacán-Cuicatlán Biosphere Reserve (México) Facing Climate Change

The Tehuacán-Cuicatlán Biosphere Reserve (TCBR), the southernmost semi-arid zone of North America, includes two dryland streams, the Río Salado (RS) and Río Grande (RG); it is surrounded by high vegetation diversity, a cacti diversification center, and the densest columnar cacti forest worldwide. However, no scientific knowledge is currently available on these dryland streams. We evaluated water quality, its relationship with the local geological characteristics, land uses, and the composition of aquatic macroinvertebrates (AM), analyzing their bioindicator potential. These results were discussed in relation to climate change predictions. The RS showed higher mineralization, salinity, hardness, water and air temperature, and low water quality index (WQI), relative to the RG. A discriminant analysis showed spatial (mineralization, salinity, and hardness in the RS) and temporal patterns (higher nitrogen compounds and temperature in the rainy season). The RS showed a lower AM diversity (40 taxa) compared to the RG (73 taxa); Ephemeroptera-Plecoptera-Trichoptera reached higher values in the RG. A co-inertia analysis identified five groups of sites with different AM assemblages and water quality characteristics. Climate change predictions for the TCBR suggest increased aridity, higher temperature, and lower rainfall, leading to reduced river flow and increased salinity and mineralization. These could alter habitat features and connectivity, with loss of AM diversity, highlighting the vulnerability of these unique ecosystems to climate change.

Re-evaluation of the role of Indian germplasm as center of melon diversification based on genotyping-by-sequencing analysis

BackgroundThe importance of Indian germplasm as origin and primary center of diversity of cultivated melon is widely accepted. Genetic diversity of several collections from Indian has been studied previously, although an integrated analysis of these collections in a global diversity perspective has not been possible. In this study, a sample of Indian collections together with a selection of world-wide cultivars to analyze the genetic diversity structure based on Genotype by Sequence data.ResultsA set of 6158 informative Single Nucleotide Polymorphism (SNP) in 175 melon accessions was generated. Melon germplasm could be classified into six major groups, in concordance with horticultural groups. Indian group was in the center of the diversity plot, with the highest genetic diversity. No strict genetic differentiation between wild and cultivated accessions was appreciated in this group. Genomic regions likely involved in the process of diversification were also found. Interestingly, some SNPs differentiating inodorus and cantalupensis groups are linked to Quantitiative Trait Loci involved in ripening behavior (a major characteristic that differentiate those groups). Linkage disequilibrium was found to be low (17 kb), with more rapid decay in euchromatic (8 kb) than heterochromatic (30 kb) regions, demonstrating that recombination events do occur within heterochromatn, although at lower frequency than in euchromatin. Concomitantly, haplotype blocks were relatively small (59 kb). Some of those haplotype blocks were found fixed in different melon groups, being therefore candidate regions that are involved in the diversification of melon cultivars.ConclusionsThe results support the hypothesis that India is the primary center of diversity of melon, Occidental and Far-East cultivars have been developed by divergent selection. Indian germplasm is genetically distinct from African germplasm, supporting independent domestication events. The current set of traditional Indian accessions may be considered as a population rather than a standard collection of fixed landraces with high intercrossing between cultivated and wild melons.