CONICET | Buscador de Institutos y Recursos Humanos

Geographic pattern of phen otypic variation can appe ar in a clin al or a mosaic fashion an d can evide nceadaptive or non-a daptive vari ation. To shed light on the mec hanism s underlying thi s vari ation, westudie d the relationships between geographic vari ation of ﬂ oral traits and both biotic and abi otic factorsof t he humm ingbi rd-pollinated plant, Nicoti ana glauca , across its natural range. We obtai ned ﬂ oralmeas ures of 38 popula tions from an area abou t 160 0 km long and 1050 km wid e and an altitu de rangefrom 7 to over 340 0 m. We used a MANOVA to detect between-popu lation differentiation s in ﬂ owertraits and a DFA to determine the traits t hat be st disc riminate bet ween popul ations. To test for assoc i-ations between ﬂ oral traits and clima tic variabl es we used correlation ana lysis. We explored any possibledistan ce-based pattern of vari ation (eithe r geographic or altitu dinal) in ﬂ oral traits or bill length ofpoll inators using Mantel tests. Fina lly, we used a multip le regression to analyze simultan eously theeffect s and relative im portanc e of abiotic predictor vari ables and bill length on corolla length. We founda high variation in ﬂ ower traits am ong popul ations. Morphom etr ic traits were the ones that bestdiscrimi nated ac ross popul ations. The re was a clinal pattern of ﬂ oral phenotypic variation explained byclimati c factors. Differences in ﬂ oral phen otypi c distan ces were str uctured by altitu dinal distan ces butnot by geograph ic distan ces. Bill le ngth of the humm ingbird poll inators was structu red both by altitu-dinal and geographic distan ces. Differences in bill lengt h of hummin gbird poll inators explained differ-ences in corolla length across popu lations . Our ﬁ ndings supp ort the assu mption of ﬂ ower evolution ata broad geographic scale. Floral t raits seem to be str uctu red not only by alti tude but also by climaticfactors.