CMS & NCTS Joint Activity - Evolution of masting -- synchronized and intermittent
Trees in mature forests often show synchronized and intermittent
reproduction, named masting. The dynamics of the resource reserves of
individuals demonstrate that, even in a constant environment, trees
may show a large between-year fluctuation in seed crops, being
synchronized over the whole forest if the fruit production is limited
by the availability of outcross pollen (pollen coupling). We studied
the conditions for masting to evolve. Assumptions are: the forest is
composed of a number of sites, each occupied by a canopy tree. After a
tree dies, the vacant site becomes available for recruitment from
seeds. We found that the regeneration dynamics of trees are very
important for masting evolution: masting will never evolve if the
vacant sites (gaps) created in a year are all filled by individuals
from seeds produced in the same year, even if seed production is
improved in mast years (via enhanced pollination efficiency and
satiating seed predators). This is because the intense competition
among seeds for acquiring the vacant site cancels out the benefit of
seed production success. Masting can evolve if seedlings can survive
over several years waiting for gap openings.
2010-01-06 11:00 ~ 2009-01-06 12:00
Prof. Yoh Iwasa (Department of Biology, Kyushu University)