Evolução correlacionada de características reprodutivas em Mutisia

Abstract

Over the evolutionary history of the Angiosperms flowers took many forms, colors and shapes with changes on these floral traits related to attract pollinators or avoid unwanted visitors, some examples of these relations are: the presence of a color pattern in a flower to attract bees and the corolla length which is related to the inaccessibility of resources, a long capitula has it’s resources more inaccessible to visitors being best visited by long-billed hummingbirds, short-billed hummingbirds become restricted to access resources on short capitule that has it’s resources more accessible. Our objective is to describe the evolutionary history of the floral morphology in the capitule in the genus Mutisia as with it’s sister species Pachylaena atriplicifolia and study the correlation of these morphological traits with color patterns. Following the phylogeny proposed in Moreira et. al (2020), the genus Mutisia is composed of 63 taxons spread in South America, 59 species occur in the Andean region and 4 species distributed in Brazil, Paraguay, Uruguay and Argentina, Mutisia species has a big and conspicuous capitula, it’s morphology vary on size, shape, color and presence of color pattern being pollinated by bees or hummingbirds. For the data, we used 40 species of the genus Mutisia and it’s sister Pachylaena atriplicifolia, with a total of 41 taxons. We collected vouchers available on virtual herbariums and made the reconstruction of it’s ancestor characters with the function fastAnc in the package phytools. To make the correlation between corolla length and color patters we used the function gls in the package nlme and the package geiger, all analysis was made in R environment. Currently in the species of the group show big capitule, it’s resources more inaccessible, more conspicuous and a round shape, with exception of the grandiflora clade. We found characters of the possible ancestor of Mutisia to show smaller capitula, more inconspicuous, more accessible and with a round shape. We couldn’t find a correlation between color pattern and corolla length, stating that theses changes occurred by different evolutionary pressures. The clade grandiflora evolved to bigger capitula with an elongated shape and without color pattern, presenting characteristics of a group specialized in hummingbird pollination, this clade inhabits the north of the Andes in the Equator, an environment with high altitude and probably low occurrence of bees. So, the presence of elongated capitula without a color pattern in this clade maybe not be due to bee avoidance, but to guarantee pollination by specializing in hummingbirds on top of hills.