Diversification of Galianthe species (Rubiaceae) in the Neotropical seasonally dry forests: A study case of a mainly subshrub genus

FLORENTÍN, J. E.; ARANA, M. D.; PRADO, D. ; MORRONE J. J; SALAS, R. M.

Copenhagen

Congreso; VII International Rubiaceae and Gentianales Conference; 2017

Galianthe isexclusivetotheNeotropicalregionandconsistsof50speciesdividedintotwosubgenera: Galianthe, with 39 South American species, and Ebelia with 11 species inMesoamerica and South America. The aims were to establish the distribution patterns ofGalianthe speciesbytrackanalysis,andtoevaluatetheircurrentdistributionbasedontheavailable tectonic information and the biogeographical regionalization of the Neotropicalregion.Atotalof(±)1400geographicalrecordsof53speciesfrom57herbariawereanalysed,representing100%ofthespeciesassignedtoGalianthe.Individualtrackswereobtainedforeach species by plotting localities and connecting them by minimum-spanning trees.Generalized tracks and nodes were determined from the spatial overlap among individualtracks.Individualandgeneralizedtracks,andnodesweregeographicallylocatedusingDIVAGIS.Generalizedtracksandnodesweresuperimposedontwomaps,oneofthemwiththebiogeographicalprovincesoftheNeotropicalregion,andtheotherwiththedistributionofNeotropicalseasonallydryforests.Fivegeneralizedtracksandfournodeswereidentified,alllocatedwithin theBrazilianandChacoan subregions.ThesenodescoincidewithalmostallfragmentsofNeotropicalseasonallydryforests.TheoriginoftheSpermacoce clade,whereGalianthe belongs,wasdatedfortheMiocene.Theearlydispersalofthespecies,alongwiththeseveralvicarianteventssuchastheriseoftheAndes,thecoolingandaridificationduringtheOligocene-Miocene,theformationoftheChacoansubregion,andthealluvialdynamicsduring the Pliocene-Holocene favoured the adaptiveradiation ofGalianthe species.In thesameway,theintimatecoincidenceoftheancestralbiotaofGalianthe withthefragmentsofNeotropical seasonally dry forests allow us to hypothesize that those remnants of forestscouldserveasrefugiaduringunfavourablegeologicperiods,andhence,influencingactivelyinthecurrentdistributionoftheirspecies.