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Estimation of gene flow in the tropical-rainforest tree Neobalanocarpus heimii (Dipterocarpaceae), inferred from paternity analysis

Konuma A, Tsumura Y, Lee CT, Lee SL, Okuda T

Mol Ecol, 2000 Nov;9(11):1843-52.
PMID: 11091320

Pollen flow and population genetic structure among 30 potentially flowering individuals of Neobalanocarpus heimii, a tropical emergent tree, were investigated in a lowland tropical rainforest of Malaysia using microsatellite polymorphism. The 248 offspring in the vicinity of five reproductive trees of the 30 potentially flowering trees were used in paternity analysis for pollen-flow study. Four primer pairs, developed in different species of dipterocarps, were adopted to detect microsatellite polymorphism. Based upon microsatellite polymorphism, pollen flow and seed migration were detected. Pollen-flow events of more than 400 m were observed directly, based on paternity analysis in the study plot. The estimated average mating distance of the five reproductive trees was 524 m. This result suggests that reproduction of this species is mediated by a long-distance pollinator. The haplotypes of some offspring were not compatible with the nearest reproductive tree. Thus, the results suggest that some seeds are dispersed by a seed dispersal vector. Investigation of genetic structure showed significant and negative correlation of genetic relatedness and spatial distances between the 30 potentially flowering trees, but this correlation was weak. We suggest that long-distance gene flow and seed migration are responsible for the poorly developed genetic structure of this species.
Comparison of the fine-scale genetic structure of three dipterocarp species

Takeuchi Y, Ichikawa S, Konuma A, Tomaru N, Niiyama K, Lee SL, et al.

Heredity (Edinb), 2004 Apr;92(4):323-8.
PMID: 14735142

We investigated the fine-scale genetic structure of three tropical-rainforest trees, Hopea dryobalanoides, Shorea parvifolia and S. acuminata (Dipterocarpaceae), in Peninsular Malaysia, all of which cooccurred within a 6-ha plot in Pasoh Forest Reserve. A significant genetic structure was found in H. dryobalanoides, weaker (but still significant) genetic structure in S. parvifolia and nonsignificant structure in S. acuminata. Seeds of all three species are wind dispersed, and their flowers are thought to be insect pollinated. The most obvious difference among these species is their height: S. parvifolia and S. acuminata are canopy species, whereas H. dryobalanoides is a subcanopy species. Clear differences were also found among these species in their range of seed dispersal, which depends on the height of the release point; so taller trees disperse their seed more extensively. The estimates of seed dispersal area were consistent with the degree of genetic structure found in the three species. Therefore, tree height probably had a strong influence on the fine-scale genetic structure of the three species.
Fulltext Paternity analysis-based inference of pollen dispersal patterns, male fecundity variation, and influence of flowering tree density and general flowering magnitude in two dipterocarp species

Tani N, Tsumura Y, Kado T, Taguchi Y, Lee SL, Muhammad N, et al.

Ann Bot, 2009 Dec;104(7):1421-34.
PMID: 19808773 DOI: 10.1093/aob/mcp252

BACKGROUND AND AIMS: Knowledge of pollen dispersal patterns and variation of fecundity is essential to understanding plant evolutionary processes and to formulating strategies to conserve forest genetic resources. Nevertheless, the pollen dispersal pattern of dipterocarp, main canopy tree species in palaeo-tropical forest remains unclear, and flowering intensity variation in the field suggests heterogeneity of fecundity.
METHODS: Pollen dispersal patterns and male fecundity variation of Shorea leprosula and Shorea parvifolia ssp. parvifolia on Peninsular Malaysian were investigated during two general flowering seasons (2001 and 2002), using a neighbourhood model modified by including terms accounting for variation in male fecundity among individual trees to express heterogeneity in flowering.
KEY RESULTS: The pollen dispersal patterns of the two dipterocarp species were affected by differences in conspecific tree flowering density, and reductions in conspecific tree flowering density led to an increased selfing rate. Active pollen dispersal and a larger number of effective paternal parents were observed for both species in the season of greater magnitude of general flowering (2002).
CONCLUSIONS: The magnitude of general flowering, male fecundity variation, and distance between pollen donors and mother trees should be taken into account when attempting to predict the effects of management practices on the self-fertilization and genetic structure of key tree species in tropical forest, and also the sustainability of possible management strategies, especially selective logging regimes.
Size-related flowering and fecundity in the tropical canopy tree species, Shorea acuminata (Dipterocarpaceae) during two consecutive general flowerings

Naito Y, Kanzaki M, Numata S, Obayashi K, Konuma A, Nishimura S, et al.

J Plant Res, 2008 Jan;121(1):33-42.
PMID: 17943228

We monitored the reproductive status of all trees with diameters at breast height (dbh) >30 cm in a 40-ha plot at Pasoh, west Malaysia, and investigated the individual fecundity of 15 Shorea acuminata Dyer (Dipterocarpaceae) trees using seed-trapping methods during two consecutive general flowering periods in 2001 (GF2001) and 2002 (GF2002). The proportion of flowering trees was higher, and not dependent on size, in GF2002 (84.2%), than in GF2001 (54.5%), when flowering mainly occurred in trees with a dbh < or =70 cm. Fecundity parameters of individual trees per event varied widely (221,000-35,200,000 flowers, 0-139,000 mature seeds, and 1.04-177 kg total dry matter mass of fruit (TDM) per tree). Monotonic increases with increasing tree size were observed for flower production and TDM amongst trees up to 90 cm in dbh, but not for mature seed production or for any of these parameters amongst larger trees. The pattern of reproductive investment during the two consecutive reproductive events clearly differed between medium-sized and large trees; the former concentrated their reproductive investment in one of the reproductive events whereas the latter allocated their investment more evenly to both reproductive events. Our results suggest size-related differences in the resource allocation pattern for reproduction.