The repeatome is composed of diverse families of repetitive DNA that keep signatures on the historical events that shaped the evolution of their hosting species. The cold seasonal Loliinae subtribe ...includes worldwide distributed taxa, some of which are the most important forage and lawn species (fescues and ray-grasses). The Loliinae are prone to hybridization and polyploidization. It has been observed a striking two-fold difference in genome size between the broad-leaved (BL) and fine-leaved (FL) Loliinae diploids and a general trend of genome reduction of some high polyploids. We have used genome skimming data to uncover the composition, abundance, and potential phylogenetic signal of repetitive elements across 47 representatives of the main Loliinae lineages. Independent and comparative analyses of repetitive sequences and of 5S rDNA loci were performed for all taxa under study and for four evolutionary Loliinae groups Loliinae, Broad-leaved (BL), Fine-leaved (FL), and Schedonorus lineages. Our data showed that the proportion of the genome covered by the repeatome in the Loliinae species was relatively high (average ∼ 51.8%), ranging from high percentages in some diploids (68.7%) to low percentages in some high-polyploids (30.7%), and that changes in their genome sizes were likely caused by gains or losses in their repeat elements. Ty3-gypsy Retand and Ty1-copia Angela retrotransposons were the most frequent repeat families in the Loliinae although the relatively more conservative Angela repeats presented the highest correlation of repeat content with genome size variation and the highest phylogenetic signal of the whole repeatome. By contrast, Athila retrotransposons presented evidence of recent proliferations almost exclusively in the
Lolium
clade. The repeatome evolutionary networks showed an overall topological congruence with the nuclear 35S rDNA phylogeny and a geographic-based structure for some lineages. The evolution of the Loliinae repeatome suggests a plausible scenario of recurrent allopolyploidizations followed by diploidizations that generated the large genome sizes of BL diploids as well as large genomic rearrangements in highly hybridogenous lineages that caused massive repeatome and genome contractions in the Schedonorus and Aulaxyper polyploids. Our study has contributed to disentangling the impact of the repeatome dynamics on the genome diversification and evolution of the Loliinae grasses.
Oceanic islands constitute natural laboratories to study plant speciation and biogeographic patterns of island endemics. Juan Fernandez is a southern Pacific archipelago consisting of three small ...oceanic islands located 600-700 km west of the Chilean coastline. Exposed to current cold seasonal oceanic climate, these 5.8-1 Ma old islands harbor a remarkable endemic flora. All known Fernandezian endemic grass species belong to two genera,
and
, of uncertain taxonomic adscription. Classical and modern classifications have placed them either in Bromeae (
), Duthieinae, Aveneae/Poeae, or Loliinae (fine-leaved
); however, none of them have clarified their evolutionary relationships with respect to their closest
relatives.
includes four species, which are endemic to Masatierra (Robinson Crusoe island) (
and
) and to Masafuera (Alejandro Selkirk island) (
and
). The monotypic
is a rare endemic species to Masatierra which is only known from its type locality and is currently considered extinct. We have used museomic approaches to uncover the challenging evolutionary history of these endemic grasses and to infer the divergence and dispersal patterns from their ancestors. Genome skimming data were produced from herbarium samples of
and
, and the 164 years old type specimen of
, as well as for a collection of 33 species representing the main broad- and fine-leaved Loliinae lineages. Paired-end reads were successfully mapped to plastomes and nuclear ribosomal cistrons of reference
species and used to reconstruct phylogenetic trees. Filtered ITS and
TLF sequences from these genomes were further combined with our large Loliinae data sets for accurate biogeographic reconstruction. Nuclear and plastome data recovered a strongly supported fine-leaved Fernandezian clade where
was resolved as sister to
. Bayesian divergence dating and dispersal-extinction-cladogenesis range evolution analyses estimated the split of the Fernandezian clade from its ancestral southern American Pampas-Ventanian Loliinae lineage in the Miocene-Pliocene transition, following a long distance dispersal from the continent to the uplifted volcanic palaeo-island of Santa Clara-Masatierra. Consecutive Pliocene-Pleistocene splits and a Masatierra-to-Masafuera dispersal paved the way for
speciation of
and
taxa.
Oritrophium (Kunth) Cuatrec. is a neotropical genus with a disjunct distribution in the Andes (Bolivia, Colombia, Ecuador, Peru, and Venezuela), the center of Mexico, and the mountains of the Guiana ...Shield in Venezuela, with a remarkable diversity in Ecuador. We present a taxonomic study for Ecuador that represents the first modern and exhaustive revision of this genus in this country. We recognize eight species and four subespecies. We provide a dichotomous key, descriptions, synonyms, morphological and nomenclatural notes, distribution maps, and photographs of living plants. Three names are lectotypified and two names are neotypified.
Mountains are paramount for exploring biodiversity patterns due to the mosaic of topographies and climates encompassed over short distances. Biodiversity research has traditionally focused on ...taxonomic diversity when investigating changes along elevational gradients, but other facets should be considered. For first time, we simultaneously assessed elevational trends in taxonomic, functional, and phylogenetic diversity of woody plants in Andean tropical montane forests and explored their underlying ecological and evolutionary causes. This investigation covered four transects (traversing ca. 2200 m a.s.l.) encompassing 114 plots of 0.1 ha across a broad latitudinal range (ca. 10°). Using Hill numbers to quantify abundance-based diversity among 37,869 individuals we observed a consistent decrease in taxonomic, functional, and phylogenetic diversity as elevation increased, although the decrease was less pronounced for higher Hill orders. The exception was a slight increase in phylogenetic diversity when dominant species were over-weighted. The decrease in taxonomic and functional diversity might be attributed to an environmental filtering process towards highlands, where the increasingly harsher conditions exclude species and functional strategies. Besides, the differences in steepness decrease between Hill orders suggest that rare species disproportionately contribute to functional diversity. For phylogenetic diversity the shifting elevational trend between Hill orders indicates a greater than previously considered influence in central Andean highlands of tropical lowlands originated species with strong niche conservatism relative to distantly related temperate lineages. This could be explained by a decreasing presence and abundance of temperate, extratropical taxa towards the central Andes relative to northern or southern Andes, where they are more prevalent.
•Patterns of taxonomic, functional and phylogenetic diversity in tropical woody plants were assessed for the first time across elevational gradients in Andean tropical montane forests.•Taxonomic, functional, and phylogenetic diversity decrease with elevation with only the exception of a slight increase in phylogenetic diversity when dominant species are over-weighted.•The decrease in taxonomic and functional diversity might be the result of environmental filtering process.•The increase in phylogenetic diversity only when focus is given to dominant species might be explained by a lesser presence of extratropical taxa towards the central Andes relative to northern or southern Andes.
(cornsalad) is a taxonomically complex genus formed by 50-65 annual Holarctic species classified into at least four main sections. Carpological traits (sizes and shapes of achenes and calyx teeth) ...have been used to characterize its sections and species. However, the potential systematic value of these traits at different taxonomic ranks (from sections to species (and infraspecific taxa)) has not been tested phylogenetically yet. Here, we have assessed the evolutionary systematic value of
diagnostic carpological traits at different hierarchical ranks and have demonstrated their ability to separate taxa at the sectional level but not at species level for species of several species pairs. A total of 426 individuals (17 species, 4 sections) of
were analyzed using AFLP and plastid data. Genetic clusters, phylogenetic trees, and haplotype networks support the taxonomic classification of
at the four studied sectional levels (
. sects.
,
,
,
) but show admixture for ten taxa from five species pairs (
,
), which are not reciprocally monophyletic. Dating analyses indicate that the
sections are relatively old (mid-Miocene), while most species diverged in the Pliocene-Pleistocene. A new section
sect.
is described to accommodate the highly divergent and taxonomically distinct
type species. Taxonomic treatments that recognize the sectional ranks and that subsume the separate species of each species pair into single species represent a natural classification for
.
Allopolyploidy is considered a driver of diversity in subtribe Loliinae. We investigate the evolution and systematics of the poorly studied Mesoamerican and South American polyploid broad-leaved ...Festuca L. species of uncertain origin and unclear taxonomy. A taxonomic study of seven diagnostic morphological traits was conducted on a representation of 22 species. Phylogenomic analyses were performed on a representation of these supraspecific taxa and all other Loliinae lineages using separate data from the entire plastome, nuclear rDNA 45S and 5S genes, and repetitive DNA elements. F. subgen. Mallopetalon falls within the fine-leaved (FL) Loliinae clade, whereas the remaining taxa are nested within the broad-leaved (BL) Loliinae clade forming two separate Mexico–Central–South American (MCSAI, MCSAII) lineages. MCSAI includes representatives of F. sect. Glabricarpae and F. subgen. Asperifolia plus F. superba, and MCSAII of F. subgen. Erosiflorae and F. sect. Ruprechtia plus F. argentina. MCSAII likely had a BL Leucopoa paternal ancestor, MCSAI and MCSAII a BL Meso-South American maternal ancestor, and Mallopetalon FL, American I–II ancestors. Plastome vs. nuclear topological discordances corroborated the hybrid allopolyploid origins of these taxa, some of which probably originated from Northern Hemisphere ancestors. The observed data indicate rapid reticulate radiations in the Central–South American subcontinent. Our systematic study supports the reclassification of some studied taxa in different supraspecific Festuca ranks.
Oritrophium (Kunth) Cuatrec. is a neotropical genus with a disjunct distribution in the Andes (Bolivia, Colombia, Ecuador, Peru, and Venezuela), the center of Mexico, and the mountains of the Guiana ...Shield in Venezuela, with a remarkable diversity in Ecuador. We present a taxonomic study for Ecuador that represents the first modern and exhaustive revision of this genus in this country. We recognize eight species and four subespecies. We provide a dichotomous key, descriptions, synonyms, morphological and nomenclatural notes, distribution maps, and photographs of living plants. Three names are lectotypified and two names are neotypified.
Oritrophium (Kunth) Cuatrec. es un género neotropical con
distribución disyunta a lo largo de los Andes (Bolivia, Colombia, Ecuador,
Perú y Venezuela), el centro de México y las montañas del Escudo Guayanés
en Venezuela, con una notable diversidad en Ecuador. Presentamos un
estudio taxonómico del género para Ecuador, el cual representa la primera
revisión moderna y exhaustiva del género en este país. Se reconocen
ocho especies y cuatro subespecies. Se incluye una clave taxonómica,
descripciones, sinonimia, observaciones morfológicas y nomenclaturales,
mapas de distribución y fotografías de las plantas en su hábitat. Tres
nombres se han lectotipificado y otros dos se han neotipificado.
Many studies have tried to assess the role of both deterministic and stochastic processes in community assembly, yet a lack of consensus exists on which processes are more prevalent and at which ...spatial scales they operate. To shed light on this issue, we tested two nonmutually exclusive, scale-dependent hypotheses: (1) that competitive exclusion dominates at small spatial scales; and (2) that environmental filtering does so at larger ones. To accomplish this, we studied the functional patterns of tropical montane forest communities along two altitudinal gradients, in Ecuador and Peru, using floristic and functional data from 60 plots of 0.1 ha. We found no evidence of either functional overdispersion or clustering at small spatial scales, but we did find functional clustering at larger ones. The observed pattern of clustering, consistent with an environmental filtering process, was more evident when maximizing the environmental differences among any pair of plots. To strengthen the link between the observed community functional pattern and the underlying process of environmental filtering, we explored differences in the climatic preferences of the most abundant species found at lower and higher elevations and examined whether their abundances shifted along the elevation gradient. We found (1) that greater community functional differences (observed between lower and upper tropical montane forest assemblies) were mostly the result of strong climatic preferences, maintained across the Neotropics; and (2) that the abundances of such species shifted along the elevational gradient. Our findings support the conclusion that, at large spatial scales, environmental filtering is the overriding mechanism for community assembly, because the pattern of functional clustering was linked to species’ similarities in their climatic preferences, which ultimately resulted in shifts in species abundances along the gradient. However, there was no evidence of competitive exclusion at more homogeneous, smaller spatial scales, where plant species effectively compete for resources.
Allopolyploidy is considered a driver of diversity in subtribe Loliinae. We investigate the evolution and systematics of the poorly studied Mesoamerican and South American polyploid broad-leaved ...Festuca L. species of uncertain origin and unclear taxonomy. A taxonomic study of seven diagnostic morphological traits was conducted on a representation of 22 species. Phylogenomic analyses were performed on a representation of these supraspecific taxa and all other Loliinae lineages using separate data from the entire plastome, nuclear rDNA 45S and 5S genes, and repetitive DNA elements. F. subgen. Mallopetalon falls within the fine-leaved (FL) Loliinae clade, whereas the remaining taxa are nested within the broad-leaved (BL) Loliinae clade forming two separate Mexico–Central–South American (MCSAI, MCSAII) lineages. MCSAI includes representatives of F. sect. Glabricarpae and F. subgen. Asperifolia plus F. superba, and MCSAII of F. subgen. Erosiflorae and F. sect. Ruprechtia plus F. argentina. MCSAII likely had a BL Leucopoa paternal ancestor, MCSAI and MCSAII a BL Meso-South American maternal ancestor, and Mallopetalon FL, American I–II ancestors. Plastome vs. nuclear topological discordances corroborated the hybrid allopolyploid origins of these taxa, some of which probably originated from Northern Hemisphere ancestors. The observed data indicate rapid reticulate radiations in the Central–South American subcontinent. Our systematic study supports the reclassification of some studied taxa in different supraspecific Festuca ranks.
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