Microsatellite Analysis of the Breeding System and Seed Dispersal in Shorea leprosula (Dipterocarpaceae)

Abstract

To understand the breeding system and seed dispersal in Shorea leprosula (Dipterocarpaceae) in Peninsular Malaysia, a microsatellite analysis was conducted of embryos of immature and mature fruits fallen in litter traps under the crowns of five trees. Outcrossed and selfed progeny mothered by the trees and those dispersed from other trees were distinguished by genotypes of three polymorphic microsatellite loci. The mean outcrossing rate of mature fruit embryos in S. leprosula pollinated by thrips (0.91) was not lower than those previously reported from Shorea species pollinated by bees, even though thrips seem to be less efficient pollinators than bees. Although four of the five trees showed high and stable outcrossing rates during fruit maturation, the outcrossing rate increased in one tree with highly selfed embryos of immature fruits. These results suggest that inbreeding depression during fruit maturation as well as self-incompatibility reduce the proportion of inbred embryos. The proportion of fruits dispersed from neighbor trees in fruits trapped under a tree crown had a mean value of 0.20 and was lowest under the tree with highly selfed embryos of immature fruits. This low fraction of dispersed fruits under this tree suggests long distances from this tree to reproductive neighbors, which may reduce cross pollination.

Nucleotide variation in the GapC region of four species of Shorea and their putative hybrids

“…On the other hand, some insights about the effective population size could be gleaned from the ecological characteristics of Shorea species. First, Shorea species are predominantly outcrossing and they are partially self-incompatible (Chan, 1981;Nagamitsu et al, 2001;Obayashi et al, 2002;Sakai et al, 1999). However, their pollinators are mainly thrips and beetles, which can migrate only limited distance (Appanah & Chan, 1981;Sakai et al, 1999).…”

“…Lee et al (2000) showed high heterozygosity in Shorea leprosula using allozyme markers. Shorea curtisii and S. leprosula were studied using microsatellites showing high (>90%) outcrossing rate (Lee et al, 2000;Nagamitsu et al, 2001;Obayashi et al, 2002). Harada et al (1994) investigated S. acuminata, S. curtisii and S. leprosula using RAPD markers and found low inter-specific nucleotide divergence and high within species diversity, suggesting that the diversification of the genus Shorea occurred only recently and/or that there is considerable gene exchange among species.…”

Reduced density due to logging and its consequences on mating system and pollen flow in the African mahogany Entandrophragma cylindricum

“…They exhibit high outcrossing rates associated with close to complete self-incompatibility (Loveless, 1992;Doligez and Joly, 1997;Nason and Hamrick, 1997). Nevertheless, in pristine or 'little disturbed' habitats pollination often occurs preferentially between neighboring conspecifics resulting in correlated matings (Murawski and Hamrick, 1991;Stacy et al, 1996;Dawson et al, 1997;Kaufman et al, 1998;Nagamitsu et al, 2001;Dutech et al, 2002) though often in association with substantial long-distance pollen dispersal (Hamrick and Murawski, 1990;White et al, 2002;Latouche-Hallé et al, 2004).…”

Comparative study of AFLP and microsatellite variation in four Dipterocarp species from natural and artificial populations in Sarawak, Malaysia

“…The reported heterozygosities of these loci in Shorea critesii were 0.591, 0.844 and 0.640, respectively (Ujino et al, 1998). Nagamatsu et al (2001) reported values of 0.568, 0.795 and 0.614 in Shorea leprosula in Pasoh Forest Reserve for the loci Shc03, Shc07 and Shc09, respectively. The heterozygosities observed in our study are similar to the values in these studies.…”

“…Significant departure from HWE was observed in D. lancelolata and S. macrophylla. The mating system of some tropical tree species has been investigated using isozymes (Murawski & Hamrick, 1991;Bawa, 1992;O'Malley & Bawa, 1987;Kitamura et al, 1994) and microsatellites (Nagamatsu et al, 2001). Shiraishi et al (1990) studied the mating system of D. aromatica using isozymes in the Andulau Forest Reserve in Brunei and found that surviving seedlings were the products of random mating.…”