Levels Of Morphological Variation Research Articles

Study of the Germination of Six Begonia Species as an Effort to Preserve Genetic Resources

Begonia is an ornamental plant that has a high level of morphological diversity. Begonia propagation is mostly done vegetatively and very rarely to propagate sexually. Therefore, this study was conducted to determine the ability of six types of Begonia seeds to germinate. Six types of Begonia, namely B. x albopicta W. Bull 'Coral Rubra', B. gambutensis Ardi & D.C.Thomas, B. multistaminea Burt-Utley, B. nelumbifolia Schltdl. & Cham., B. ulmifolia Wild. and B. varipeltata D.C.Thomas. were grown in a petri dish and placed in a growth chamber with a temperature of 23.6 ℃, humidity of 74.5%, and a light intensity of 3,431 lux. The results showed that the different types of Begonia showed significant differences in all the parameters tested. B. nelumbifolia required 7.89 ± 0.18 days to germinate and is the fastest time than other types. The highest percentage of seed germination was also obtained by this species, amounting to 63.22%. In addition, B. nelumbifolia showed the best response to the germination rate coefficient, germination rate index, and germination index. This study revealed complete information about the germination of six types of Begonia. In addition, the ability to produced many seeds and the ease of germination made this plant have the potential to be cultivated through seeds. Furthermore, the information can be used as a basis for seed storage as an ex-situ conservation method to maintain genetic diversity.

Morphological and ecogeographical diversity analysis of maize germplasm in the high altitude Andes region of Ecuador

AbstractThe Andean region of Ecuador is the place of origin of many maize landraces grouped into 24 races. Definition of priorities for maize diversity conservation in this region can be supported by the spatial identification of areas with a high eco-geographical and phenotypic diversity. Six hundred thirty-six maize samples were morphologically characterized using 14 descriptors and assigned to a distinctive race. Additionally, sampled farms were characterized by 12 environmental variables. From these data, maps of morphological and eco-geographical diversity were obtained by using techniques to determine eco-geographical and phenotypic distances and applying them to each geographical neighbourhood. The races Patillo Ecuatoriano, Racimo de Uva and Uchima exhibited high intra-racial morphological variation, particularly in the shape of the ear, kernel row layout, cob diameter and total kernel number. The highest number of different races was observed in Imbabura, Azuay and Chimborazo provinces. The highest levels of morphological diversity were found in three cells (10 × 10 km), located in Pichincha, Chimborazo and Loja provinces. Two ecological niches, located in Loja province, showed high levels of eco-geographical diversity. A comparison between diversity maps revealed shared hotspots of morphological and eco-geographical diversity in the central and southwest areas of Imbabura province. The Andean highlands of Ecuador are an optimal refuge for the conservation of maize diversity, and the criteria of eco-geographical and morphological diversity and race richness should be considered when defining priority in situ conservation areas.

Assessing the potential for deep learning and computer vision to identify bumble bee species from images

Pollinators are undergoing a global decline. Although vital to pollinator conservation and ecological research, species-level identification is expensive, time consuming, and requires specialized taxonomic training. However, deep learning and computer vision are providing ways to open this methodological bottleneck through automated identification from images. Focusing on bumble bees, we compare four convolutional neural network classification models to evaluate prediction speed, accuracy, and the potential of this technology for automated bee identification. We gathered over 89,000 images of bumble bees, representing 36 species in North America, to train the ResNet, Wide ResNet, InceptionV3, and MnasNet models. Among these models, InceptionV3 presented a good balance of accuracy (91.6%) and average speed (3.34 ms). Species-level error rates were generally smaller for species represented by more training images. However, error rates also depended on the level of morphological variability among individuals within a species and similarity to other species. Continued development of this technology for automatic species identification and monitoring has the potential to be transformative for the fields of ecology and conservation. To this end, we present BeeMachine, a web application that allows anyone to use our classification model to identify bumble bees in their own images.

Morphological variation in two sigmodontine rodents along the mainland and the Fuegian archipelago in Chilean southern Patagonia

BackgroundAnalysis of morphological variation in archipelagos has been essential to understand the evolution of terrestrial vertebrates. In particular, these natural scenarios allow to assess morphological changes experienced by insular fauna compared to their mainland counterparts. In mammals, morphological changes of insular forms have been observed in size and shape of body and cranial traits. The southern Patagonia of Chile represents a unique scenario to analyze morphological variation in two of the most widely distributed small rodents along western southern South America: Abrothrix olivacea and Oligoryzomys longicaudatus.MethodsWe applied linear and three-dimensional geometric morphometric tools to analyze the variation in cranial morphology of A. olivacea (N = 80) and O. longicaudatus (N = 49). Sampled localities were distributed in the mainland and islands of the Fuegian archipelago in Chilean Patagonia. Standard multivariate methods, as Principal Components Analysis, and Logistic Regression models were carried out to evaluate differences in size and shape of crania.ResultsWe detected higher levels of morphological variation in the crania of A. olivacea if compared to O. longicaudatus. The variation was associated to cranial size instead of shape.We observed significant differences between insular and mainland individuals in A. olivacea, being the cranium size of this species significantly bigger on islands. Indeed, specimens of A. olivacea from “Isla Wellington”, exhibited the higher increment in cranium size compared to any other mainland and insular site sampled for this species. In contrast, insular and mainland forms of O. longicaudatus did not show significant differences in cranial morphology.ConclusionsWe suggest that the patterns of morphological variation observed in these two small rodents along Patagonia, could be explained in terms of the historical biogeography of the region, and the different ecological features of the studied species.

Geometric morphometrics of large South American camelids and their potential for the taxonomical identification in archaeological sites of the northern Argentina

ABSTRACT The large South American camelids, the llama (Lama glama) and the guanaco (Lama guanicoe), present a low level of morphological variation in the skeleton and a significant overlap in their body size at population scale. Therefore, if we consider the inter-specific and intra-specific variability, it is difficult to distinguish between wild (guanaco) and domestic (llama) species, based only on osteometric analysis of remains from archaeological sites. Techniques based on 2D geometric morphometric were applied in order to test their power for the taxonomic identification of these two camelids species through shape study of three anatomic elements: the first anterior and posterior phalanges, and the glenoid fossa of scapula. A total of 59 skeletal elements of 29 modern individuals and 14 archaeological specimens were analysed. The morphogeometric evaluation differentiated the skeletal element shapes of modern camelids groups. The archaeological samples revealed the presence of llama and guanaco in the archaeological record of the Argentinean Northwest at 1900–1300 BP. Nevertheless, domestic species were dominant in Antumpa site, whereas wild species were better represented in Condor II. This exploratory study provided an advance in the efforts of taxonomic identification of bone remains from the shape analysis performed on modern individuals of living species.

Индикаторные признаки адаптации субтропических древесных растений на основе комплексных исследований

For the Lower Volga region with difficult soil and climatic conditions, forecasts bear an increase in the length of the growing season, an increase in heat, and a softer winters. This indicates the need for studies of subtropical plants for an objective assessment of the identification of mechanisms for their adaptation and prospects for creating protective forest plantations in sparsely wooded regions. Theoretical and practical interest for the Volgograd region is a valuable fruit, medicinal, forest reclamation and ornamental shrub (unabi) plant Zizyphus jujuba Mill. (family Rhamnaceae). The purpose of the research is to study the ecological and physiological features of subtropical woody plants of Zizyphus jujuba and to identify indicator signs of their adaptation in the Volgograd region. The objects of research were the varietal plants of the unabi (Ta-yang-zao, Southerner - large-fruited, Druzhba, Phenicia - medium-fruited, Sochi, Temryuk - small-fruited). They are tested in the Volgograd region for the first time, obtained from the FSBI (city of Sochi) and are cultivated in FSBI FNTS Agroecology RAS (Volgograd region, Russia). The soils of the experimental plot (50 ° 4´-50 ° 5´N and 45 ° 22´-45 ° 23´E) are characterized by a low humus content (from 0.57 to 1.15%). It was revealed that the study area (Volgograd region) is characterized by a small amount of precipitation, low temperatures in winter, high temperatures in summer, droughts of high and medium intensity. The amplitude of the absolute maxima and minima varies from seventy-eight (dry steppe) to ninety degrees Celsius (semi-desert). It has been established that the agroclimatic resources of natural distribution areas differ from the introduction points of Zizyphus jujuba Mill. to culture. Different levels of morphological variability, as well as water availability, lead to a change in the ability to expend and retain water, to a lack of moisture in the leaves of Z.jujuba. The insignificant effect of drought on the state of the aboveground plant organs during the arid periods was observed in medium-sized and large-fruited varieties. Young, non-lignified shoots are damaged (at an air temperature of about 40 ° C and a decrease in air humidity of up to 10%). A decrease in leaf turgor was observed with water deficit indicators of 28.3-35.8%. Water deficiency decreases by 6-10% with increasing age, which is due to increased adaptation and regulation of water balance. According to the indicators of the relative electrolyte yield, groups were determined according to the degree of drought resistance: low - Southerner, Ta-Yan-Zao (4.23-4.71), medium - Finik, Friendship (3.10-3.61) and high - Temryuk, Sochi (1.64-1.99). Ecological tolerance of various organisms to low temperatures is quite specific. Evaluation of different varieties of Zizyphus jujuba under light-brown soils showed that the adaptation of plants to low temperatures increases with increasing age. In small varieties with an increase in age, the damage is minor. Based on the vegetation experience, the limits of ecological tolerance of small-fruited forms of Zizyphus jujuba to chloride salinity were established, which makes it possible to predict their successful cultivation on soils with a chlorine ion content of 0.1%. Thus, complex ecological and physiological studies of the adaptive capacity of subtropical plants Zizyphus jujuba revealed indicator signs that allow to evaluate and predict the degree of adaptation depending on the variety and the response to stress factors specific to the conditions of the Lower Volga region.

Signatures of echolocation and dietary ecology in the adaptive evolution of skull shape in bats

Morphological diversity may arise rapidly as a result of adaptation to novel ecological opportunities, but early bursts of trait evolution are rarely observed. Rather, models of discrete shifts between adaptive zones may better explain macroevolutionary dynamics across radiations. To investigate which of these processes underlie exceptional levels of morphological diversity during ecological diversification, we use modern phylogenetic tools and 3D geometric morphometric datasets to examine adaptive zone shifts in bat skull shape. Here we report that, while disparity was established early, bat skull evolution is best described by multiple adaptive zone shifts. Shifts are partially decoupled between the cranium and mandible, with cranial evolution more strongly driven by echolocation than diet. Phyllostomidae, a trophic adaptive radiation, exhibits more adaptive zone shifts than all other families combined. This pattern was potentially driven by ecological opportunity and facilitated by a shift to intermediate cranial shapes compared to oral-emitters and other nasal emitters.

Ocena genetičke raznolikosti genotipova tvrde pšenice prema karakteristikama koje je definisao UPOV

Estimation of the level of durum wheat germplasm genetic diversity is important for its classification and efficient use in breeding programmes. The aim of this study was to assess genetic diversity of durum wheat genotypes developed at the Institute of Field and Vegetable Crops in Novi Sad, Serbia, with 26 morphological characteristics based on the International Union for Protection of New Varieties of Plants guidelines. The Shannon diversity index was used as an indicator of morphological diversity and it ranged from 0.283 for glaucosity of lower side of the flag leaf blade and density of hairiness of uppermost node of the culm, to 0.950 for the ear colour, with the mean value of 0.616, indicating a medium to high level of morphological diversity. On average, the diversity was higher for traits relating to generative organs than for those associated with vegetative plant organs. The 21 morphological characteristics were sufficient to distinguish unique profiles of all durum wheat genotypes. The estimation of varietal diversity and identification of morphological characteristics with the highest discriminative power were done by multiple correspondence analysis. The traits that contributed the most to the distinction of genotypes were the ear colouration, length of beak of the lower glume, lower glume shape, ear length of awns at tip relative to ear length and colour of awns. Morphological characterization using the traits with the highest discriminative power could be a useful complementary method for durum wheat germplasm classification and diversity analysis.

Intraspecific variation and population ecology of Sinanodonta woodiana (Bivalvia, Unionidae) in connection with the introduction of this species in Ukraine

The bivalve mollusc Sinanodonta woodiana Lea, 1834, Chinese pond mussel is a species that quickly colonizes new territories. The article presents the results of research of the morphology and ecology of the Chinese pond mussel from a Repida River (Matroska Village, Odessa Oblast) and a pond in the Hnylop’yat River basin (Romanivka Village, Zhytomir Oblast). The biomass, density, age and sex structure of the populations of these animals were analyzed. The biomass of molluscs is 227.1 and 133.5 g/m2 from the Repida River and a pond in the Romanivka Village, respectively, the density is 1.8 and 0.5 ind./m2. The age structure of the population of S. woodiana is formed by juveniles (the number of 2–3 year old molluscs is 39.5 and 57.1% of two biotopes, respectively), individuals of middle age (4–6 years old – 51.2 and 38.1%) and individuals of the senior group (9.3 and 4.8%). The ratio of age groups in the age structure is 0.8 : 1 : 0.2 for molluscs from the River Repida and 1.5 : 1 : 0.1 for a S. woodiana from the pond. In the sex structure of the molluscs from Repida River males dominated (female: male ratio is 0.7 : 1), but in the sex structure of the investigated group from a pond females were quantitatively superior to males (1.3 : 1). The presence of a significant proportion of young individuals indicate an active reproduction of the local populations. We found glochidia in the gills of females of S. woodiana with a shell length of 9.3–17.5 cm. That is, even with slow growth rates of molluscs in a reservoir with a natural temperature condition of northern Ukraine, they are capable of reproduction at 2 years of age. The data on morphometry of the shells of Chinese pond mussels and biotopical preferences of investigated population of these mollusсs are given. The high level of morphological variability of the shells of S. woodiana, in particular their shape and color, is presented. In the river near the Matroska Village, the average length of a shell is 106±9.7 mm. Molluscs from the pond in the Romanivka Village have larger sizes (132.4±6.9 mm). S. woodiana have a relatively high, short (H/L index value is 0.68 and 0.61 in molluscs from the Repida River and a pond in the Romanivka Village, respectively) and rather convex shell (W/L index is 0.37 and 0.39). After acclimatization under the new conditions, a change in the morphometric indices of the shell in mollusсs from the pond in the Romanivka Village is noticeable. Thus, a statistically significant decrease in the H/L index and an increase in the W/H index in mollusсs from the pond were noted. There were no statistically significant differences in the W/L index. Consequently, mollusсs, introduced into the pond, had an absolute increase in the size of the shell and a relative decrease in its height. The low water temperature does not limit the spread of S. woodiana.

Phenotypic variability of Pyrus boissieriana Buhse: Implications for conservation and breeding

Pyrus boissieriana appears to be a promising species for its use as rootstock for the commercial pear (P. communis L.) in lowland areas prone to drought and flooding. The current study was conducted on the evaluation of phenotypic diversity among 102 accessions of wild pear (P. boissieriana). The accessions studied showed significant differences in terms of all the measured characters. The leaf length ranged from 19.33 to 51.33 mm and leaf width varied from 17.13 to 48.75 mm. The fruit length ranged from 8.26 to 22.51 mm and the range of 10 fruit weight was from 2.48 to 72.00 g. Fruit weight showed positive correlations with bunch length, bunch weight, fruit length, and fruit width. Principal component analysis (PCA) showed that the first eight PCs explained 80.47% of the total variance and the characters such bunch weight, fruit length, fruit width, fruit diameter, fruit weight, and fruit flesh length were the key characters in the present data set, which differentiated the accessions belonging different areas. The dendrogram obtained based on the measured characters grouped the accessions into three main clusters and indicated the existence different levels of morphological variation among the accessions, which is applicable and useful for pear breeding programs. The finding obtained here confirmed that the northern and northeastern parts of Iran are rich sources of pear genetic diversity which this valuable gene pool should be in situ and ex situ conserved.

Morphological and genetic analysis of batak fish (Tor soro) in North Sumatera

Research on the analysis of morphological and genetic variations of Batak fish (Tor soro) in North Sumatra has been conducted. The Batak fish samples were captured from flowing rivers at several districts in North Sumatera namely: Bahorok River (Langkat), Alian River (Toba Samosir), Batang Toru River (South Tapanuli). Truss method was used to analyze morphological parameters by using SPSS ver. 16.0 computer program, while the genetic parameters were analyzed by scoring amplified DNA strands visualized in electrophoresis using Polymerase Chain Reaction – Random Amplified Polymorphism DNA (PCR-RAPD) method. Primers used in this study were: OPA-02, OPA-03, OPA-04, OPC-01 and OPC-02. The PCR amplicons were then analyzed by using Numerical Taxonomy and Multivariate Analysis System (NTSYS) ver. 2.02. computer program. Dendrogram analysis showed that the level of morphological variability was at 1–25 euclidean distance. Dendogram analysis also showed that genetic diversity level was within coefficient of 0.23–0.71 in which obtained a diversity level of 48%. Based on the morphological and genetic results, it may be indicated that the Batak fishes originating from Batang Toru had a close similarity with Alian’s rather than Bahorok’s.

Hind wing variation in Leptura annularis complex among European and Asiatic populations (Coleoptera, Cerambycidae).

The ability to quantify morphological variation is essential for understanding the processes of species diversification. The geometric morphometrics approach allows reliable description of variation in animals, including insects. Here, this method was used to quantify the morphological variation among European and Asiatic populations of Leptura annularis Fabricius, 1801 and its closely related species L. mimica Bates, 1884, endemic for Japan and Sakhalin islands. Since the taxonomic status of these two taxa is differently interpreted by taxonomists, they are collectively called “Leptura annularis complex” in this paper. The analysis was based on the measurements of hind wings of 269 specimens from six populations from Europe and Asia. The level of morphological divergence between most of continental European and Asiatic populations was relatively small and proportional to the geographic distance between them. However, distinct morphotype was detected in Sakhalin Is. and Japan. These data confirm the morphological divergence of the endemic L. mimica species. Obtained results highlight the potential of the geometric morphometric method in studying morphological variation in beetles.

Morphology and phylogenetic position of three species of genus Camptocercus Baird, 1843 (Cladocera: Anomopoda: Chydoridae).

Morphology of three species of the cladoceran genus Camptocercus Baird, 1843 (Anomopoda: Chydoridae), North Asian C. streletskayae Smirnov, 1998, Australian C. australis Sars, 1896 and Neotropical C. dadayi Stingelin, 1913, is investigated. Revealed data confirm a high level of morphological diversity within the genus. C. australis and C. dadayi belong to the uncinatus-clade of the genus, while C. streletsakayae is an advanced species with unclear phylogenetic position within the genus.

A new subterranean Maraenobiotus (Crustacea: Copepoda) from Slovenia challenges the concept of polymorphic and widely distributed harpacticoids

Maraenobiotus slovenicus sp. nov. is described from subterranean waters of a very cold, temporary karstic spring in the vicinity of Velika Pasica cave, central Slovenia. A detailed examination of numerous specimens reveals a low level of morphological variability in this population. Morphological characters traditionally used in the genus Maraenobiotus Mrázek, 1893 would identify our population as a subspecies of the polymorphic and widely distributed M. vejdovskyi Mrázek, 1893. This species was reported from the Palearctic, with at least six accepted subspecies, some of which have been reported in sympatry or parapatry, sometimes even without any apparent niche partitioning. One of these subspecies, M. vejdovskyi truncatus Gurney, 1932, originally described from the UK and later on also reported from Italy and Japan, shares with our population the extremely reduced female principal caudal setae. However, a closer examination of the caudal armature and other characters reveals significant differences between these disjunct populations. We propose a hypothesis of distinct species within the M. vejdovskyi-complex, and critically review all recognized and some unrecognized morphotypes and subspecies. As a result, three new species names are proposed for previously reported populations from Italy and Japan: Maraenobiotus galassiae sp. nov.; M. isidai sp. nov.; and M. pescei sp. nov. Four subspecies of M. vejdovskyi are now elevated to the full specific rank: M. anglicus Gurney, 1932; M. arctica Löffler; M. tenuispina Roy; and M. truncatus Gurney, 1932. This hypothesis remains to be tested using molecular (and other) tools, but can serve as a viable alternative to the concept of polymorphic and widely distributed freshwater harpacticoids.http://zoobank.org/urn:lsid:zoobank.org:pub:92302CF9-21BA-4454-A3DD-337BB7152DCE

Taxonomic implications of morphological variation in three species of Trinomys (Rodentia: Echimyidae) from eastern Brazil.

Trinomys is a genus of terrestrial spiny rats from the Atlantic Forest, and three species occur in the state of Espírito Santo, eastern Brazil: T. gratiosus, T. paratus, and T. setosus. The levels of morphological variation within and among these species are virtually unknown, and their geographic ranges have not been properly assessed. These three species are externally very similar, hampering their identification in surveys and ecological studies that are not based on voucher specimens. We evaluated 162 specimens of Trinomys spp. from eastern Brazil, especially from the state of Espírito Santo, and used data from skulls, skins, and bacula to examine morphological variation and its taxonomic implications. We found extensive morphological variation in the skins and skulls even when diagnostic characters were examined, such as the number of dental lophs and bones contributing to the postorbital process. We also found variation in bacular shape among and within species, including polymorphism among individuals from the same population. The geographic range of each species in Espírito Santo was well defined: T. setosus occurred on the left (north) bank of the Doce River, and the other two species, T. gratiosus and T. paratus, occurred on the right (south) bank of this river; however, T. gratiosus was found at altitudes above 500 m, whereas T. paratus occurred below 580 m. Despite difficulties in species identification, the results of morphological and morphometric analyses are compatible with the current classification of these three species. In addition, the level of morphological variation found in specimens identified as T. g. panema--including types--falls within the range of T. g. gratiosus, confirming the taxonomic status of the former as a junior synonym of the latter.

A comparative study of morphospace occupation of mesopelagic fish assemblages from the Canary Islands (North-eastern Atlantic)

The morphology of fishes plays a very important role in the ecosystem biodiversity to show different evolutionary strategies. The morphological variations among species can be graphically represented in a morphospace and analysed using different methods. In this study we used different assemblages of mesopelagic fishes living in the Canary Islands (North-eastern Atlantic) to compare two methods: convex hull and patterning. The results demonstrated that the patterning of morphospace allowed understanding better the specific ecological strategies and structure of fish assemblages. By contrast, the convex hull is focused on a reduced number of species with a high level of morphological diversity which is located in the periphery of the morphospace. The study demonstrates that patterning analysis is a better tool for comparing these assemblages than convex hull, and it highlights the relevance of the distribution of points within the morphospace for characterizing fish assemblages.

Natural variation in fruit characteristics and seed germination of Jatropha curcas in Benin, West Africa

SummaryAn investigation was conducted in the ten phytodistricts of Benin, West Africa, in order to assess the level of morphological variation in Jatropha curcas seed and their germination potential. Hierarchical classification of the morphological traits of seeds identified five morphotypes, using 54% of the overall morphological information. Canonical discriminant analysis performed on the five morphotypes revealed highly significant differences. Morphotype 1 included seeds from the phytodistricts of Côtier, Pobè, The Ouémé Valley, and Plateau. Morphotype 2 and Morphotype 5 seeds were from the phytodistricts of Bassila, Zou, and Borgou-Sud; while Morphotype 3 and Morphotype 4 seeds were from the phytodistricts of Borgou-Nord, the Atacora Chain, and Mekrou-Pendjari. Significant morphological variation existed within the seeds as a consequence of genetic make-up and/or environmental effects. Seed from Mekrou-Pendjari and the Atacora Chain were black, smooth, light (0.67 g seed–1), and small (1.76 cm-long and 1.15 cm-wide). Seed from Plateau, Côtier,The Ouémé Valley, and Pobè zones were brown, rough, heavy (0.84 g seed–1), and large (1.97cm-long, 1.2 cm-wide). All seed germination started 4 d after sowing and ended between day-7 and day-8. Seed germination timing varied significantly with morphotype.

Comparison of four DNA extraction methods on various tissues and types of Sechium edule ( Jacq.) Sw.

Sechium edule is an important crop in Southern Mexico and Central America, and Mexico was the main producer, with 53% of the world production in 2012. This species presents high levels of morphological variation that have resulted in different types of varieties not clearly defined. However, morphological characteristics have not been sufficient to classify S. edule varieties, and it has been difficult to study the species genetic diversity. Because of it, there is a need to develop methods for studying the genetic diversity in S. edule. In this regard, the first step is to find a suitable DNA extraction method. For this reason, in this study four DNA extraction methods (two laboratory protocols, and two commercial kits) were compared for their efficiencies in yield and quality of DNA obtained from four different tissues of four S. edule types. Clear effects of extraction methods, types and tissues of S. edule were observed on DNA yield and quality.

Homage to Hutchinson, and the role of ecology in lineage divergence and speciation

AbstractAimA fundamental goal of biogeography is to explain why sister taxa are allopatric. Potential explanations include insufficient time for range expansion, adaptation to allopatrically distributed environments, or ecological similarity that prevents coexistence. Many sister species have been isolated for hundreds of thousands of years, providing ample time to attain sympatry. This focuses attention on the role of ecology. Allopatric phylogroups and phylogenetic sister species often exhibit morphological differences that are apparent responses to differing ecological conditions, revealing a role for ecology in lineage divergence and speciation. However, as Hutchinson proposed five decades ago, a certain level of morphological divergence is typically required before two taxa can partition resources and coexist. This paper uses ecological niche modelling and phylogeography to explore the role of niche divergence in shaping the ranges of sister taxa and in the speciation process.LocationAridlands of North America including the Sonoran and Chihuahuan deserts and Baja California.MethodsEcological niche models were constructed for avian sister phylogroups on either side of two biogeographical barriers: the Vizcaino Desert in Baja California (c. 28°–30° N), and the Cochise Filter Barrier, which divides the Sonoran and Chihuahuan deserts. Each phylogroup pair was tested for differences in niche identity and niche divergence (using the background test).ResultsNiche identity can be rejected for each phylogroup, although tests of niche divergence were insignificant.Main conclusionsAllopatric sister phylogroups exist in and respond to aspects of different environments, as shown by significant niche identity tests, leading to geographical variation that is often recognized taxonomically, supporting a role for ecology in lineage divergence. However, sister phylogroups also use shared ancestral components of the climatic niche more often than expected by chance, which might prevent selection from yielding divergence in traits related to resource use. Climatic niche divergence does not explain allopatric ranges of phylogroups. Allopatry is maintained because the phylogroups are too similar morphologically, lacking the necessary Hutchinsonian ratios for coexistence. The role of ecology in speciation differs between lineage and biological species concepts owing to their different ranking criteria.

Phenotypic and Genetic Uniformity in Three Populations of Panax notoginseng by Mass Selection

Aim: Panax notoginseng is an important traditional Chinese medicinal plant. Although the species has been cultivated for more than 400 years, a certified variety is still not available. Natural populations (NP) exhibit high levels of morphological variation and genetic diversity, suggesting that mass selection may be used to improve P. notoginseng. In previous studies, we established 38 mass selection populations based on certain morphological traits (target characters) and eliminated undesirable individuals over five successive generations. The objective of the present study was to evaluate phenotypic and genetic uniformity of three of these populations: purple-stem (PSP), green-stem (GSP), and erect-type (ETP) populations. Methods: To assess phenotypic uniformity, 12 morphological traits were measured in NP and the three selected populations. Genetic uniformity of these four populations was also evaluated using inter-simple sequence repeat (ISSR) markers. Results: Phenotypic uniformity was only exhibited with respect to target characters, including stem color in PSP and GSP, and petiole-peduncle angle in ETP. Average coefficients of variation detected for most non-target characters in PSP, GSP, and ETP were similar or higher to those of NP. When these four populations were analyzed using 129 ISSR markers, the percentage of polymorphic bands detected was 72.27% in PSP, 76.40% in GSP, 58.34% in ETP, and 76.23% in NP. Genetic identities (I) in PSP, GSP, and ETP were 0.9058, 0.8663, and 0.8703, respectively, with a value greater than 0.7814 in NP. Conclusion: Mass selection is an efficient way to improve target characters and genetic uniformity in P. notoginseng. Nevertheless, selection of specific individuals exhibiting comprehensive phenotypic traits may be necessary to accelerate the breeding process.