This study examines species divergence time and phylogenetic relationships across 195 plant taxa using two widely used chloroplast molecular markers, rbcL and matK, analysed through Bayesian Inference in MrBayes under relaxed molecular clocks. Divergence time estimation was calibrated against seven fossil constraints, including Palaeonitella cranii (≥ 410 Ma), Rhyniophyta/Cooksonia (420–430 Ma), and Archaefructus sinensis (125–130 Ma). Three datasets, rbcL, matK, and the concatenated rbcL+matK dataset, were analysed under the GTR + G + I substitution model to evaluate marker performance. The concatenated rbcL+matK dataset produced the deepest and most precisely constrained divergence estimates, dating land plant origin to 457.6 MYA, seed plant emergence to approximately 330 MYA, crown angiosperm radiation to 138.7 MYA, and the monocot–eudicot split to 125.0 MYA, all consistent with established fossil benchmarks. Sequence statistics revealed contrasting levels of nucleotide diversity between the two markers. Tajima’s D values differed among datasets, but because sampling was interspecific rather than population-based, we interpreted these statistics descriptively rather than as direct evidence of specific selective or demographic processes. The combined dataset displayed intermediate diversity (π = 0.1758) alongside narrower highest posterior density (HPD) intervals, reflecting improved estimation precision. The resulting time-calibrated phylogeny resolved 13 major clades spanning charophyte outgroups (447.60 MYA) through gymnosperms (412.25 MYA), pteridophytes, bryophytes, and monocots (395.08 MYA), to all eudicot superclades, providing a broad temporal framework across major geological intervals. Single-gene analyses revealed systematic limitations: rbcL underestimated deep divergence times, while matK generated wider HPD intervals at shallow nodes. The concatenated dataset generally showed stronger node support, fewer apparent polytomies, and narrower 95
Invasive climbing plants are among the most aggressive groups in tropical ecosystems, largely due to their high competitive capacity, which is still poorly understood in the early stages of growth. In this study, we investigated the effects of interactions between the invasive Cryptostegia madagascariensis and two native species from Northeast Brazil, Cenostigma bracteosum and Piptadenia retusa,during initial establishment under two light conditions. We conducted experiments on intra- and interspecific competition, varying the combinations of species while maintaining a density of two plants per pot and including a control treatment (single plants), under two light conditions (full sun and 50
The influence of a changing climate on the phenology of organisms in a region is dependent on how regional climate cues the timing of local life history events and how those cues are changing over time. There is extensive evidence of phenological shifts in flowering time over the past 50 years in response to increasing temperatures in temperate regions, but far less is known about tropical regions where seasonality is less temperature driven. We examined historical datasets of flowering patterns in two guilds of ornithophilous plants in the montane cloud forests of Monteverde, Costa Rica in order to test the hypothesis that drought accumulation patterns rather than temperature cue flowering. Bimonthly censuses of flower production were used to quantify flower production during two sampling periods:1981–1983, 1986–1991, the species studied here appear to cue flowering patterns to either accumulated drought units or a combination of accumulated drought units and chill units prior to flowering. These results have implications for how tropical cloud forest plants will respond to climate change to the extent that drought and chill patterns are changing with time.
The genus Bistorta (Polygonaceae) includes several medicinally important species, yet genomic resources remain limited for many taxa. In this study, we assembled and annotated the complete chloroplast genomes of B. vacciniifolia and B. griffithii and compared them with previously published genomes within the genus. Both genomes exhibited the typical quadripartite structure of angiosperm chloroplasts and showed highly conserved gene content and organization. Comparative analyses identified several highly variable regions and potential molecular markers, while phylogenetic reconstruction clarified relationships within Bistorta and across Polygonaceae. These results provide new genomic resources and contribute to understanding chloroplast genome evolution and phylogenetic relationships in the genus.
