Geographic variation of floral traits in Nicotiana glauca: Relationships with biotic and abiotic factors. Acta Oecologica

NATTERO J.; SÉRSIC, A. N.; COCUCCI A. A.

ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY

GAUTHIER-VILLARS/EDITIONS ELSEVIER

Lugar: Paris; Año: 2011 vol. 37 p. 503 - 511

1146-609X

p { margin-bottom: 0.25cm; line-height: 120%; }Geographic patternof phenotypic variation can appear in a clinal or a mosaic fashionand can evidenceadaptive or non-adaptive variation. To shed light onthe mechanisms underlying this variation, westudied therelationships between geographic variation of floral traits and bothbiotic and abiotic factorsof the hummingbird-pollinated plant,Nicotiana glauca, across its natural range. We obtainedfloralmeasures of 38 populations from an area about 1600 km long and1050 km wide and an altitude rangefrom 7 to over 3400 m. We used aMANOVA to detect between-population differentiations in flowertraitsand a DFA to determine the traits that best discriminate betweenpopulations. To test for associ-ations between floral traits andclimatic variables we used correlation analysis. We explored anypossibledistance-based pattern of variation (either geographic oraltitudinal) in floral traits or bill length ofpollinators usingMantel tests. Finally, we used a multiple regression to analyzesimultaneously theeffects and relative importance of abioticpredictor variables and bill length on corolla length. We foundahigh variation in flower traits among populations. Morphometrictraits were the ones that bestdiscriminated across populations.There was a clinal pattern of floral phenotypic variation explainedbyclimatic factors. Differences in floral phenotypic distances werestructured by altitudinal distances butnot by geographic distances.Bill length of the hummingbird pollinators was structured both byaltitu-dinal and geographic distances. Differences in bill length ofhummingbird pollinators explained differ-ences in corolla lengthacross populations. Our findings support the assumption of flowerevolution ata broad geographic scale. Floral traits seem to bestructured not only by altitude but also by climaticfactors.