Academic literature on the topic 'Syngaméon'

The eastern North American white oaks, a complex of approximately 16 potentially interbreeding species, have become a classic model for studying the genetic nature of species in a syngameon. Genetic work over the past two decades has demonstrated the reality of oak species, but gene flow between sympatric oaks raises the question of whether there are conserved regions of the genome that define oak species. Does gene flow homogenize the entire genome? Do the regions of the genome that distinguish a species in one part of its range differ from the regions that distinguish it in other parts of its range, where it grows in sympatry withdifferent species? Or are there regions of the genome that are relatively conserved across species ranges? In this study, we revisit seven species of the eastern North American white oak syngameon using a set of 80 single-nucleotide polymorphisms (SNPs) selected in a previous study because they show differences among, and consistency within, the species. We test the hypothesis that there exist segments of the genome that do not become homogenized by repeated introgression, but retain distinct alleles characteristic of each species. We undertake a range-wide sampling to investigate whether SNPs that appeared to be fixed based on a relatively small sample in our previous work are fixed or nearly fixed across the range of the species. Each of the seven species remains genetically distinct across its range, given our diagnostic set of markers, with relatively few individuals exhibiting admixture of multiple species. SNPs map back to all 12 Quercus linkage groups (chromosomes) and are separated from each other by an average of 7.47 million bp (± 8.74 million bp, SD), but are significantly clustered relative to a random null distribution, suggesting that our SNP toolkit reflects genome-wide patterns of divergence while potentially being concentrated in regions of the genome that reflect a higher-than-average history of among-species divergence. This application of a DNA toolkit designed for the simple problem of identifying species in the field has two important implications. First, the eastern North American white oak syngameon is composed of entities that most taxonomists would consider “good species.” Second, and more fundamentally, species in the syngameon are genetically coherent because characteristic portions of the genome remain divergent despite a history of introgression. Understanding the conditions under which some loci diverge while others introgress is key to understanding the origins and maintenance of global tree diversity.

Using the traditional research methods, based on the example of local and cultivated representatives of the Tacamahaca (Spach) Penjkovsky subgenus growing in Russia and neighboring countries, the concept of a species in poplars (genus Populus L., Salicaceae) has been developed. It is suggested that the sections of black poplars (Aigeiros Duby) and balsamic poplars (Tacamahaca Spach) in Eurasia form a single supraspecific system with a common gene pool, which is very similar to syngameon. The taxonomic species that make up such a system are different dynamic states of this system and exist in the equilibrium state between natural selection, which forms and preserves the specifics of each dynamic state, and gene flows from other taxonomic species. Such a system can also be considered as a large Linnaean species represented by many subspecies or even geographical and ecological races. The use of molecular genetic methods for the taxonomic species study in the Populus genus is difficult due to the powerful flow of genes between the species, since the species differ in a small number of genes responsible for adaptive characters. The sections of the subgenus Tacamahaca poplars are ecological. The combination of species in these sections is not so much about the unity of their origin, but about the common growing conditions: black poplars tend to grow in lowlands, while the balsamic poplars tend to grow in the mountains, with which the poplars’ diagnostic characters are associated. In nature, belonging to a certain section is more profitable than the intermediate state, but in cultivation and in the urban environment, the opposite situation is observed.

AbstractIn the present work, numerous species of useful and wild plants were identified in the archaeobotanical samples (moat deposit and two ceramic jugs) collected from the mediaeval locality of the Kolno Castle, near Brzeg, south-western Poland. At the confluence of two rivers, in the vicinity of the castle, it was possible to cultivate cereals on poor alluvial soil, in the ground with a layer of ferruginous concretions. The characteristic weeds of the classes Secalinetea and Chenopodietea indicated the cultivation of winter cereals and garden plants. Polymorphic populations of millet were cultivated. Apart from the annual plants, the following fruit trees were grown: plums, peaches and walnuts. Fruits of many wild species were also gathered for consumption. Correlation analysis of the characters of Prunus L. stones proved that the development of the organ is conservative. Morphometric analysis of the plum stones showed that in addition to the specimens belonging to the species Prunus spinosa L. and Prunus domestica L./Prunus insititia L., there were hybrids between these two species. Multivariate analyses evidenced that the complexes of cultivated and wild plums and cherries can form hybrid syngameons revealing continuous variation and non-random structure. The variability of filbert nuts corresponded to the variability of a large modern population of this species that is composed of many genetically different morphotypes. Variabilities of inter-specific units of fossil and contemporary forms belonging to various taxa were described by ellipsoids of various shapes and arrangements in the three-dimensional ordination space.

Background: Quercus is recognized as a taxonomically complex genus, but also as a model clade in many important fields in biology, such that a good recognition of its species is necessary. The chosen species concept to use in Quercus will determine the empirical criteria used to recognize them, which will impact several areas of knowledge. Questions: What are the main sources of variation that hinder the delimitation of species in Quercus? What species concepts we use explicitly to recognize species in Quercus? What is the advantage of using different empirical criteria both integrally and simultaneously in delimitation of species of oaks? Studied species: Species of Quercus Method: Bibliographic review of the main sources of variation in Quercus, and the species concepts, specifically those used in Quercus. Results: Plasticity, convergence, hybridization and introgression, and incomplete divergence were identified as the main sources of variation in oaks. Taxonomic and ecological species concepts are those mainly and traditionally used in Quercus. Syngameons are important to know and understand the biology and evolution of Quercus species. These systems indicate that there are preserved genes that provide coherence and morphologic, ecologic and genetic identity to species, even if hybridization, backcrossing and introgression occur. Conclusions: Preserved genes that provide coherence to species, suggest using taxonomic, ecologic and genetic concepts to delimit problematic species in species complexes in Quercus. The simultaneous use of data that these concepts support (multicriteria analysis), will give more confidence to get closer to the nature of the species and build an integrative taxonomy.

Les forêts tropicales abritent la plus grande diversité d'espèces au monde, un fait qui reste en partie inexpliqué et dont l'origine est sujette à débat. Même à l'échelle de l'hectare, les forêts tropicales abritent des genres riches en espèces, avec des espèces d’arbres étroitement apparentées qui coexistent en sympatrie. En raison de contraintes phylogénétiques, on s'attend à ce que les espèces étroitement apparentées possèdent des niches et des stratégies fonctionnelles similaires, ce qui questionne les mécanismes de leur coexistence locale. Les espèces étroitement apparentées peuvent former un complexe d'espèces, composé d’espèces morphologiquement similaires ou qui partagent une importante proportion de leur variabilité génétique en raison d'une ascendance commune récente ou d'hybridation, et qui peut résulter d'une radiation écologique adaptative des espèces selon des gradients environnementaux. Malgré le rôle clé des complexes d'espèces dans l'écologie, la diversification et l'évolution des forêts néotropicales, les forces éco-évolutives qui créent et maintiennent la diversité au sein des complexes d'espèces néotropicales restent peu connues. Nous avons exploré la variabilité génétique intraspécifique comme un continuum au sein de populations structurées d'espèces étroitement apparentées, et mesuré son rôle sur la performance individuelle des arbres à travers la croissance dans le temps, tout en tenant compte des effets d'un environnement finement caractérisé au niveau abiotique et biotique. En combinant des inventaires forestiers, des données topographiques, des traits fonctionnels foliaires et des données de capture de gènes dans la station de recherche de Paracou, en Guyane Française, nous avons utilisé la génomique des populations, les analyses d'associations environnementales et génomiques, et la modélisation Bayésienne sur les complexes d'espèces Symphonia et Eschweilera clade Parvifolia. Nous avons montré que les complexes d'espèces d'arbres couvrent l’ensemble des gradients locaux de topographie et de compétition présents dans le site d'étude alors que la plupart des espèces qui les composent présentent une différenciation de niche marquée le long de ces mêmes gradients. Plus précisément, dans les complexes d'espèces étudiés, la diminution de la disponibilité en eau, par exemple depuis les bas-fonds jusqu’aux plateaux, a entraîné une modification des traits fonctionnels foliaires, depuis des stratégies d'acquisition à des stratégies conservatrices, tant entre les espèces qu'au sein de celles-ci. Les espèces de Symphonia sont génétiquement adaptées à la distribution de l'eau et des nutriments, elles coexistent donc localement en exploitant un large gradient d'habitats locaux. Inversement, les espèces d'Eschweilera sont différentiellement adaptées à la chimie du sol et évitent les habitats les plus humides et hydromorphes. Enfin, les génotypes individuels des espèces de Symphonia sont différentiellement adaptés pour se régénérer et croître en réponse à la fine dynamique spatio-temporelle des trouées forestières, avec des stratégies adaptatives de croissance divergentes le long des niches de succession. Par conséquent, la topographie et la dynamique des trouées forestières entraînent des adaptations spatio-temporelles à fine échelle des individus au sein et entre les espèces des complexes d'espèces Symphonia et Eschweilera. Je suggère que les adaptations à la topographie et à la dynamique des trouées forestières favorisent la coexistence des individus au sein et entre les espèces des complexes d'espèces, et peut-être plus généralement entre les espèces d'arbres de forêts matures. Dans l'ensemble, je soutiens le rôle primordial des individus au sein des espèces dans la diversité des forêts tropicales, et suggère que nous devrions élaborer une théorie de l'écologie des communautés en commençant par les individus, car les interactions avec les environnements se produisent après tout au niveau de l’individu
Tropical forests shelter the highest species diversity worldwide, a fact that remains partly unexplained and the origin of which is subject to debate. Even at the hectare-scale, tropical forests shelter species-rich genera with closely-related tree species coexisting in sympatry. Due to phylogenetic constraints, closely related species are expected to have similar niches and functional strategies, which raises questions on the mechanisms of their local coexistence. Closely related species may form a species complex, defined as morphologically similar species that share large amounts of genetic variation due to recent common ancestry and hybridization, and that can result from ecological adaptive radiation of species segregating along environmental gradients. Despite the key role of species complexes in Neotropical forest ecology, diversification, and evolution, little is known of the eco-evolutionary forces creating and maintaining diversity within Neotropical species complexes. We explored the intraspecific genomic variability as a continuum within structured populations of closely related species, and measured its role on individual tree performance through growth over time, while accounting for effects of a finely-characterized environment at the abiotic and biotic level. Combining tree inventories, LiDAR-derived topographic data, leaf functional traits, and gene capture data in the research station of Paracou, French Guiana, we used population genomics, environmental association analyses, genome-wide association studies and Bayesian modelling on the tree species complexes Symphonia and Eschweilera clade Parvifolia. We showed that the species complexes of Neotropical trees cover all local gradients of topography and competition and are therefore widespread in the study site whereas most of the species within them exhibit pervasive niche differentiation along these same gradients. Specifically, in the species complexes Symphonia and Eschweilera clade Parvifolia, the decrease in water availability due to higher topographic position, e.g., from bottomlands to plateaus, has led to a change in leaf functional traits from acquisitive strategies to conservative strategies, both among and within species. Symphonia species are genetically adapted to the distribution of water and nutrients, hence they coexist locally through exploiting a broad gradient of local habitats. Conversely, Eschweilera species are differentially adapted to soil chemistry and avoid the wettest, hydromorphic habitats. Last but not least, individual tree genotypes of Symphonia species are differentially adapted to regenerate and thrive in response to the fine spatio-temporal dynamics of forest gaps with divergent adaptive growth strategies along successional niches. Consequently, topography and the dynamics of forest gaps drive fine-scale spatio-temporal adaptations of individuals within and among distinct but genetically connected species within the species complexes Symphonia and Eschweilera clade Parvifolia. Fine-scale topography drives genetic divergence and niche differentiation with genetic adaptations among species, while forest gap dynamics maintains genetic diversity with divergent adaptive strategies within species. I suggest that adaptations of tree species and individuals to topography and dynamics of forest gaps promote coexistence within and among species within species complexes, and perhaps among mature forest tree species outside species complexes. Overall, I defend the primordial role of individuals within species in tropical forest diversity, suggesting that we should develop a theory of community ecology starting with individuals, because interactions with environments happen after all at the individual level