Loss of genetic diversity in tropical trees: effects of seed disperser behavior.

BRAVO, S.P.

Miami

Congreso; The Association for Tropical Biology and Conservation Meeting; 2004

The Association for Tropical Biology and Conservation

Loss of genetic diversity as effect of seed disperser behaviour   S.P.Bravo Laboratorio de Ecología Funcional. Depto. Ecología, Genética y Evolución. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Ciudad Universitaria Pab.II 4piso. 1428 Buenos Aires. Argentina. sbravo@bg.fcen.uba.ar   Seed dispersers may favor gene flow, reduce endogamy and promote genetic diversity within plant population. However, depending on the food choice by the disperser and on the pattern of seed distribution that it generates (e.g. clumped), the disperser activities could result in a decrease of genetic diversity, instead of its increase. A high level of clumping characterizes the seed dispersal pattern produced by howler monkeys (Alouatta spp). Black howlers (Alouatta caraya), in particular, are the most abundant arboreal frugivore in flooded forest along Paraná River from northern Argentina. This important seed disperser mammal tends to use seeds of Ocotea diospyrifolia infested by Heilipus spp. Larva in the study site. The larva consumes the seed endosperm and the embryo and consequently damages the seeds if black howlers do not consume them. The passage through the black howler digestive tract eliminates the larvae. Trees with a large percentage of infested fruits exhibit a slow rate of germination, however if the seeds passes through the digestive tract of black howlers, its germination rates tend to be higher and similar to germination rates of seeds from trees with low proportion of infested seeds. Black howlers are the main dispersers of O. diospyrifolia in study site; 90 % of these tree species sapling are established in black howler’s latrines. Black howlers food choice facilitates the reproduction of the slow germination phenotypes (the trees heavily infested by the larvae), perhaps promoting the loss of genetic diversity O. diospyrifolia populations.