CONICET | Buscador de Institutos y Recursos Humanos

Abstract: We analyzed the flowering pattern (flowering period length, plant floral display) of 43Asteraceae species, co-occurring in natural populations of Chaco Serrano forests from centralArgentina. We considered the expected influences imposed by climate (variations in temperature,photoperiod, rainfall, and frosts), animal-plant interactions (richness and frequency of the floralvisitors), some plant attributes (plant growth form and seed dispersal mechanism), and phylogeneticrelationships among species. Cluster and null-model analyses were used to evaluate whether patternsof flowering times are aggregated, segregated, or random. Results showed that flowering phenologywas significantly correlated with the seasonal variation in temperature, photoperiod, rainfall, andfrosts. Cluster analysis showed the following groups: 1) species with long flowering periods, low plantfloral display, low frequency of visits of a few number of insect species, anemochorous fruits, andherbaceous growth form; 2) species with long flowering periods, low plant floral display,comparatively intermediate values of frequency and number of species of floral visitors, seed dispersalmechanisms other than anemochory, and mostly herbaceous plants; and 3) species with shortflowering periods, high plant floral display, high frequency of visits of a large number of species offloral visitors, mostly anemochorous and shrubby plants, with a tendency to a segregated floweringpattern. The three groups also differ in their phylogenetic membership: all basal species (except one)were classified within the cluster 2, while the other two clusters were composed by derived specieswithin Asteraceae. Our study clarifies some promising hypotheses concerned with the selective forcesthat underlie the patterns that can be related to the different ecological strategies evidenced withinthis group of co-occurring Asteraceae species.