Estudo comparativo de duas espécies ornitófilas em borda de uma ilha de mata de galeria, Uberlândia-MG

Abstract

The Angiosperms present some kinds of interactions with animals including mutualistic interactions associated with pollination. Plants developed flower morphology adapted to attract different vectors in order to make pollination functional. Diverse floral characters suchas color, shape, size and floral resource are adapted to groups of taxonomically related pollinators and can be viewed as pollination syndromes. The bird-pollinated flowers generally are tubular, strong colors like red, orange and pink, absence of odor, abundant nectar, diurnal anthesis and separation between the nectar chamber and the stigma and anthers. Amongst the birds that visit flowers, the hummingbirds present specializations such small body, fine, long and/or bending beak, agility when visiting hanging/pendant flowers, spatial memory and other characteristics that allow them to use floral resources. The objective of this study is to analyze the floral biology, pollination and the reproductive system, of two bird-pollinated species. Gaylussacia brasiliensis (Ericaceae) and Costus spiralis (Costaceae) are two species pollinated by hummingbird that occur nearby on the edge of an island of gallery forest in the Ecological reserve of the Clube Caça e Pesca Itororó de Uberlândia - MG. These plants present differences in the amount of nectar produced, distribution in the environment, size and shape of the flowers, and number of flowers per individual. G. brasiliensis e C. spiralis are adapted to pollination by different group of hummingbirds, Trochilinae and Phaethornithinae respectively. Gaylussacia brasiliensis presents a shorter corolla tube and produces smaller amounts of nectar than C. spiralis. It is has a contagious distribution in the environment and opens many flowers per inflorescences and individual, receiving visits from less specialized Trochilinae hummingbirds. On the other hand, Costus spiralis presents flowers with longer and curved tube produces nectar in larger amounts and higher sugar concentration than G. brasiliensis. It is distributed in the environment in low density groups and each inflorescence produces only one or two flowers per day. This more specialized strategy requires pollinators that have longer and slightly curved beaks. These differences found in floral morphology, distribution and nectar associates to morphologic differences, metabolism and behavior of the hummingbirds allow the coexistence of these species in the nature.