ABSTRACT
The integration of morphological and molecular data is essential to understand the affinities of fossil taxa and spatio-temporal evolutionary processes of organisms. However, homoplastic morphological characters can mislead the placement of fossil taxa and impact downstream analyses. Here, we provide an example of how to mitigate effectively the effect of morphological homoplasy on the placement of fossil taxa and biogeographic inferences of Cissampelideae. We assembled three data types, morphological data only, morphological data with a molecular scaffold and combined morphological and molecular data. By removing high-level homoplastic morphological data or reweighting the morphological characters, we conducted 15 parsimony, 12 undated Bayesian and four dated Bayesian analyses. Our results show that the 14 selected Cissampelideae fossil taxa are placed poorly when based only on morphological data, but the addition of molecular scaffold and combination of morphological and molecular data greatly improve the resolution of fossil nodes. We raise the monotypic Stephania subg. Botryodiscia to generic status and discover that three fossils previously assigned to Stephania should be members of Diploclisia. The Bayesian tip-dated tree recovered by removing homoplastic morphological characters with a Rescaled Consistency Index <0.25 has the highest stratigraphic fit and consequently generates more reasonable biogeographic reconstruction for Cissampelideae. Cissampelideae began to diversify in Asia in the latest Cretaceous and subsequently dispersed to South America around the Cretaceous-Palaeogene boundary. Two dispersal events from Asia to Africa occurred in the Early Eocene and the Late Eocene-Late Oligocene, respectively. These findings provide guidelines and practical methods for mitigating the effects of homoplastic morphological characters on fossil placements and Bayesian tip-dating, as well as insights into the past tropical floristic exchanges among different continents.
Subject(s)
Menispermaceae , Phylogeny , Menispermaceae/anatomy & histology , Menispermaceae/genetics , Bayes Theorem , Phylogeography , Fossils , Time FactorsABSTRACT
Cissampelos sympodialis Eichl. é uma espécie empregada na medicina popular do Nordeste do Brasil, cujos estudos farmacológicos são bastantes promissores no tratamento de doenças do trato respiratório. Neste trabalho realizou-se um estudo farmacobotânico de suas folhas, com o objetivo de elaborar morfodiagnoses macroscópicas e microscópicas que auxiliem sua caracterização. Realizaram-se secções paradérmicas (lâminas) e transversais de folhas (lâmina e pecíolo), posteriormente clarificadas e coradas com safranina e safrablue, respectivamente, e observadas ao microscópio óptico. Cissampelos sympodialis caracteriza-se pelas folhas peltadas, com as lâminas deltóides, nervação actinodroma-broquidodroma, e o pecíolo espessado nas extremidades. A epiderme é hipoestomática, com células de paredes anticlinais ondeadas na face adaxial e irregularmente sinuosa a ondeada na abaxial. O mesofilo é dorsiventral e o sistema vascular do pecíolo é formado de um anel de feixes isolados colaterais. Esparsos idioblastos de cristais prismáticos foram observados no parênquima peciolar. A morfologia foliar em conjunto com a anatomia da epiderme são caracteres distintivos para Cissampelos sympodialis.
Cissampelos sympodialis Eichl. is a plant species used in popular medicine in Northeast of Brazil, whose pharmacological studies are very promising in the treatment of diseases of the respiratory tract. In this work, a pharmacobotanical study of the leaves was performed with the objective to elaborate a macroscopical and microscopical morphodiagnosis to support its characterization. The microscopical morphodiagnosis was done with paradermic sections on the blades and cross sections on the blades and petioles followed by clarification and coloring with safranin and safrablue, respectively, and examined by optical microscopy. Cissampelos sympodialis has peltate leaves with deltoid blades with actinodromous -brochidodromous nervation, and the petioles are swollen at the extremities. The epidermis is hipostomatic with anticlinal walls of epidermal cells waved in the upper surface and irregularly sinuate to wavy on the lower surface. The mesophyll is dorsiventral and the vascular system of the petiole is formed by a ring of 6-7 free collateral bundles. Sparce idioblasts of prismatic crystals in parenchyma of petiole were observed. The morphology of the leaves and the anatomy of epidermis are distinguishing characters of Cissampelos sympodialis.