Perspectives in Plant Ecology Evolution and Systematics最新文献

The asymmetric pattern in species richness is a notable feature across different lineages and geographic regions. While some lineages have high richness, diversity and wide distribution, others have the opposite. Despite low rates of diversification, the latter might also be phylogenetically isolated. Lineages that accumulate these characteristics are known as “depauperons'' and explaining their existence and persistence through time is still a challenge. The plant family Melastomataceae contains both megadiverse lineages (such as the tribe Miconieae, with around 1900 species) and groups with few species (such as the tribes Eriocnemeae, Lithobieae, and Rupestreeae with 7, 1 and 2 species, respectively). These three clades are restricted to eastern Brazil, where they have been seldom studied. The lack of information about their basic biology as well as which processes determine their distribution have not been previously studied. Here we integrated metrics of dispersal ability, species distribution models (SDMs) and natural history data compilation in order to uncover common patterns shared by these depauperons in Melastomataceae and raise conservation concerns. For all nine species we estimated the dispersal ability and generated SDMs in different time-periods (past, present and future). Dispersal ability was associated with predicted distribution models under future scenarios to evaluate shifts and/or retractions in suitable areas. In addition, we compared the climatic tolerances of the depauperons with their megadiverse sister tribes via climatic envelopes. Overall, our results indicate limited dispersal ability, dependency on water for dispersal, and restricted niche as common characteristics for all species in the deupauperon tribes Eriocnemeae, Lithobieae and Rupestreeae. Our analyses also show that the climatic niche spaces of the depauperons are limited and totally included within the niche space of its sister tribes. Based on our findings, the level of threat in these groups can be potentiated by rapid climate change, mainly due to their inability to spread over long distances, restricted niches and increased habitat fragmentation. We suggest that future conservational actions prioritize these unique taxa in Melastomataceae, especially if a phylogenetic diversity perspective is taken into account.

Campo rupestre and campo de altitude are two highly diverse plant formations that are found in montane areas in eastern Brazil. These formations are associated with landscapes having different geological histories and are part of different phytogeographic domains under different climatic conditions. It is unclear however, whether lineages in each area have different diversification dynamics and climatic niche evolution. Here we analyze biogeographical history, climatic niche evolution and diversification dynamics of the Cambessedesieae (Melastomataceae), a clade with many endemics in each formation. We use a time-calibrated phylogenetic tree alongside carefully curated distribution points to estimate ancestral ranges and compare diversification dynamics and climatic niche evolution across the group, using models of geographical range evolution (BioGeoBEARS), diversification dynamics (BAMM, GeoSSE) and trait-evolution (l1ou). Our results show that Cambessedesieae is a relatively old (Early Eocene, 48 Mya) clade in comparison to other lineages of similar distribution. An initial split between lineages that are mainly endemic to either formation happened earlier, but, surprisingly, these two lineages have similar diversification dynamics and climatic niche evolution. Shifts in climatic regimes in extant lineages occurred more recently and are not associated with changes in diversification rates. Overall, we show that lineages endemic to montane areas and having different geological histories and in different climatic and phytogeographic contexts can have similar diversification patterns.

The aim of this study was to determine physiological and molecular grounds for high adaptation potential of invasive populations of Rosa rubiginosa to soil drought. We assume that the invasive populations possess specific and effective adaptive mechanisms making them capable pioneer and nurse plants in dry environments. By colonizing the land, they limit its degradation and initiate revitalization of areas damaged by soil droughts. We analyzed plant water status, the photosynthetic apparatus activity, carbohydrate and phenolic content, the level of non-enzymatic antioxidants and RbcL protein associated with fixation of CO₂. The research involved native (Northern Hemisphere: Poland, Spain) and invasive (Southern Hemisphere: Argentine, New Zealand) populations. Contrary to the native population, the invasive one demonstrated soil drought induced specific responses aimed at maintaining high water potential in the leaves, greater content of soluble carbohydrates, and higher osmotic potential. In the invasive population, the accumulation of soluble carbohydrates prevailed over their consumption for the synthesis of phenolic compounds. The invasive plants also maintained high content of assimilation pigments and showed greater level of non-enzymatic antioxidants. Reduced activity of the photosynthetic apparatus was associated both with increased energy amount dissipated from PSII and the efficiency with which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors. The study results pave the path for further research on the genetic basis of sweet briar response to soil drought in the context of progressive steppe formation and desertification.

In Brazil, the country with the highest plant species richness in the world, biodiverse savannas and grasslands – i.e., grassy ecosystems, which occupy 27% of the country – have historically been neglected in conservation and scientific treatments. Reasons for this neglect include misconceptions about the characteristics and dynamics of these ecosystems, as well as inconsistent or regionally restricted terminology that impeded a more adequate communication about Brazil's savannas and grasslands, both within the country and internationally. Toward improved communication and recognition of Brazil’s diversity of ecosystems, we present the key drivers that control the main types of grassy ecosystems across Brazil (including in regions of the country where forests dominate). In doing so, we synthesize the main features of each grassy ecosystem in terms of physiognomy and ecological dynamics (e.g., relationships with herbivores and fire). We propose a terminology both for major grassland regions and for regionally relevant vegetation physiognomies. We also discuss terms associated with human land management and restoration of grassy ecosystems. Finally, we suggest key research needs to advance our understanding of the ecology and conservation values of Brazil’s grassy ecosystems. We expect that a common and shared terminology and understanding, as proposed here, will stimulate more integrative research that will be fundamental to developing improved conservation and restoration strategies.

Seed dispersal is an essential ecological process for plant (re)colonization, especially in intensively human-altered habitats such as old-fields (i.e. abandoned farmlands) where seed arrival is often limited. Assessment of spatial patterns of mammal-generated seed rain and their matching with the spatial distribution of adult plants provides essential information on the patterns and pace of the (re)colonization processes. For instance, increased seedling survival far from adult plants could indicate density-dependent mortality (Janzen-Connell) effects whereas increased survival close to adult plants could suggest facilitative effects. Here, we characterized during two dispersal seasons the spatial distribution of feces from four frugivorous mammals and quantified its spatial association with the distribution of adult plants of the pioneer Mediterranean dwarf palm (Chamaerops humilis) in two old-fields in southwestern Spain. We also estimated the dispersal kernels of both emerged and surviving seedlings and assessed potential evidence for Janzen-Connell and/or facilitative effects. Using a spatially explicit approach, we revealed strong differences between study sites in the strength and scale of spatial associations between mammal feces with C. humilis seeds and adult dwarf palms, being strongly positive at small scales in one site and slightly positive at larger scales in the other one. Further, we found some evidence of both Janzen-Connell and facilitative effects depending on the study site. Altogether, our results emphasize the central role as seed disperser of the Eurasian badger (Meles meles) in the natural (re)colonization of Mediterranean old-fields and the spatial variations of the underlying mechanisms and demographic consequences for plant populations.

Among the fascinating and highly specialized vascular plants in the hyperarid core of the Chilean and Peruvian Atacama Desert there are few Tillandsia species from the bromeliad family (Bromeliaceae). These grow epiarenically on bare sand without a functional root system, and in some rare cases they build up a monospecific and often the only landscape characterizing vegetation type, which is called Tillandsiales or Tillandsia loma. Tillandsia landbeckii is the dominating epiarenic species in Chile totally dependent on fog serving as the only water resource. Herein we elaborate on the hypothesis that migration and multiple colonization in concert with putative introgression from other Tillandsia species build up the present day phylogeographic distribution pattern and may contribute to the evolutionary dynamics and long-term success in hyperarid desert systems. Genomic analyses using GBS (genotyping-by-sequencing) data from the nuclear and plastid genome were conducted at the population level. A genome skimming approach was used to generate reference plastome data. The results indicate that both, multiple colonization and secondary contact of old gene pools and interspecies geneflow, contribute to present-day population genetic structure. Local-scale analysis also indicates that these past footprints of evolutionary history do contribute to present-day local adaptive potential of the species.

Grime’s CSR classification of functional strategies in terms of competitors, stress-tolerators and ruderals provides a helpful framework for understanding and predicting vegetation responses to environmental changes. To evaluate the importance of alternative processes that structure plant communities, it is useful to disentangle the community functional variation into interspecific and intraspecific components and assess their degree of co-variation. Few efforts have been made to investigate the habitat filtering theory in all the interspecific and intraspecific components of a plant community. We hypothesized that under intense climatic conditions, such as drought and cold, functional diversity would decrease towards the dominance of stress tolerant strategies, and that such trends would be reinforced by similar variation at the intraspecific level. We investigated the effect of climatic variation on functional diversity and on community-weighted mean along an elevation gradient in central Italy that ranges from dry and warm climatic conditions at lower elevation to cold and moist ones at higher elevation. We ran regression models to disentangle the total community components for both functional diversity and community-weighted mean into interspecific effect, intraspecific effect and their covariation along the climatic gradient. Our observations were in line with the theory of habitat filtering: we found lower diversity of the Grime strategy for species at both warmer and colder climatic conditions, with dominance of the stress-tolerant strategy. Similarly, the intraspecific effect was lower in cold conditions but higher under drier conditions, which seems to indicate that different processes act at the level of individuals. Given the important intraspecific variability observed in this study, it can be proposed that investigations of vegetation communities should take the role of intraspecific variability into greater consideration.

The orchid genus Ophrys is a textbook example of a taxonomic controversy, with the number of species recognised in different classifications varying from around 10 to over 350, causing confusion among researchers and enthusiasts. Here, we illustrate that there are multiple drivers behind that disagreement, representing debates and discussions of various nature, and then reflect on strategies to mitigate confusion among the users of Ophrys taxonomies, reconciling legitimate taxonomic debates with demands for clarity among the broader biological community. First, we distil six possible factors explaining taxonomic disagreement from general literature on taxonomic difficulties, and assess the importance of each of them for the Ophrys controversy. We then explore two strategies to reduce confusion among the users of the taxonomies in question. On the one hand, we illustrate the possibility of constructing a consensus-based reference taxonomy for external users, despite the ongoing taxonomic disagreement, and on the other hand we explore a ‘pluralist’ alternative, in which different classifications are allowed to coexist, but in an orderly manner. Doing so, we build a case for the Ophrys systematics community to reflect collectively on which strategy to adopt.

Recently diverged species may hybridize in their contact zones if complete reproductive isolation has not yet emerged. Petunia inflata and P. interior are closely related species with a narrow geographic distribution in Argentina and southern Brazil. They share morphological features, genetic markers, pollinators, and occupy a transitional area between the Pampa grasslands and the Brazilian Atlantic Forest. Here, we used genomic data to verify species boundaries, identify putative hybrids, and shed light on their speciation process. We characterized 59 individuals from allopatric and contact zones using genotyping-by-sequencing technology, resulting in a final dataset with 21,759 neutral single nucleotide polymorphisms used to perform structure, demographic, and hybridization analyses. These species belong to distinct evolutionary lineages that hybridized after secondary contact. A combination of geographic distance, elevation, and climate explains the genetic divergence between species. Niche overlap analysis revealed that even though these species have overlapping distributions and similar habitat preferences, they are more distinct than expected by chance, rejecting the niche conservatism hypothesis. Demographic analysis suggested that the Pleistocene climatic changes led species to diverge but they came into secondary contact during the Holocene. The secondary contact led to limited gene flow between species and bidirectional introgression. The distribution expansion of these species’ ancestor to a transitional zone between biomes, associated with elevational ranges and habitat fragmentation promoted speciation and niche differentiation.