Simao-Bianchini, R. | bioRxiv Science

bioRxiv2024

Too hot for the weeds? Exploring the impact of climate change in herbaceous Convolvulaceae in Cerrado and Mata Atlantica biomes (SE Brazil)

AimWe investigated the potential resilience to climatic change of nine species of weeds in Convolvulaceae, using predictive spatial modeling across two contrasting biomes in Southeastern Brazil: Cerrado (=Savanna) and Mata Atlantica (=Atlantic Forest). We inferred future changes in distribution area, the climatic variables that will be most impactful, and the potential occurrence of future climatic refuges. LocationSoutheastern Brazil (Sao Paulo, Brazil). MethodsA total of 195, taxonomically vetted, distribution records were compiled for nine species of Convolvulaceae. Potential distribution areas were modelled in RStudio 1.3.1056 with R 3.6.3 using modleR; environmental layers used were the 19 bioclimatic variables with 30 seconds resolution. After a correlation analysis, four bioclimatic variables were selected for distribution modelling: Temperature Seasonality (BIO4), Mean Temperature of Wettest Quarter (BIO8), Precipitation of Wettest Month (BIO13) and Precipitation of Driest Quarter (BIO17). The species distribution modelling was performed using the Maxent algorithm for the present time (1960-1990) and for future projections (2050 and 2070), under two different scenarios of projections, moderate and pessimistic.. The final distribution models were generated through the selection of primary models with a minimum level of TSS (True Skills Statistics) equal to 0.7. ResultsThe analysed species demonstrated different levels of response to climatic change: Distimake aegyptius, D. dissectus, and Evolvulus pteurocaulon exhibited a gain in the climatic suitability range, regardless of the future scenarios. Other species, such as E. glomeratus, Ipomoea bonariensis, and I. alba showed a decline in climatic suitability range, more accentuated in the pessimistic scenario. Three species showed a positive response in a moderate future scenario, but a decline in the most extreme projection. Areas that may act, in the future, as climatic refuges for the displaced species are also highlighted, in view of being prioritised for conservation. Main ConclusionThis study reveals that climate change will have varied impacts on herbaceous species of Convolvulaceae occurring in the Brazilian Cerrado and Mata Atlantica biomes. Some species are likely to benefit from climate change, showing an increase in climatic suitability in both moderate and pessimistic future scenarios. Other species, however, are expected to experience a decline in suitable climatic conditions, in particular under the most pessimistic climatic scenario, and are more likely to be threatened in the future, due to the constriction of suitable habitats. The analysis also highlights that certain regions may serve as important climatic refuges for these species in the future. These findings emphasize the necessity for targeted conservation plans to protect the biodiversity of the Cerrado and Mata Atlantica phytogeographic domains and weed management strategies - not only in the present but also in future climatic conditions.

ecology↗

bioRxiv2023

Barking up the wrong tree: the importance of morphology in plant molecular phylogenetic studies

Background and aimsKeraunea is a genus recently described in Convolvulaceae, though it has sat uncomfortably in this family. A recent molecular phylogenetic study suggests that its two morphologically almost identical species actually belong to different families, Malpighiaceae (Superrosids) and Ehretiaceae (Superasterids), although with little-to-no morphological evidence to support it. Material and methodsSequences of matK, rbcL, and ITS for all the 77 currently accepted genera of Malpighiaceae, K. brasiliensis and Elatinaceae (outgroup) were compiled from Genbank and analysed with Maximum Likelihood and Bayesian Inference criteria for nuclear, plastid and combined datasets. Additional database and herbarium studies were performed to locate and analyse all duplicates of the holotype of K. brasiliensis to check for misidentified or contaminated materials. Key resultsOur examination of expanded DNA datasets and herbarium sheets of all K. brasiliensis isotypes revealed that an error in tissue sampling was, in fact, what led to this species being placed in Malpighiaceae. Kews isotype had a leaf of Malpighiaceae (likely from Mascagnia cordifolia) stored in the fragment capsule, which was unfortunately sampled and sequenced instead of the actual leaves of K. brasiliensis. ConclusionsDNA sequences can be helpful in classifying taxa when morphology is conflicting or of a doubtful interpretation, with molecular phylogenetic placement becoming a popular tool that potentially accelerates the discovery of systematic relationships. However, good knowledge of plant morphology is essential for formulating the phylogenetic hypotheses to be tested and for a critical re-interpretation of the results in the context of biological information of the species or families. Thus, these techniques are, much like any others, prone to methodological errors. We highlight the crucial need to observe plant morphology alongside molecular phylogenetic results, particularly when the new hypotheses are in disagreement with the existing classification and at risk of incurring gross taxonomic mistakes.

plant biology↗