Demographic History of Shorea curtisii (Dipterocarpaceae) Inferred from Chloroplast DNA Sequence Variations

Abstract

We assessed the variability of chloroplast DNA sequences in populations of the dipterocarp forest tree, Shorea curtisii. This species is widely distributed in hill and coastal hill dipterocarp forests of the Malay Peninsula, whereas isolated populations are found in the coastal hills of north Borneo. Two chloroplast DNA regions (1555 bp of trnH-psbA-trnK and 925 bp of trnL-trnF) were sequenced from 123 individuals collected from six Malay Peninsula and two Bornean populations. There were 15 chloroplast haplotypes derived from 16 polymorphic sites. A haplotype network revealed two distinct haplogroups that correlate with two geographic regions, the Malay Peninsula and Borneo. These two haplogroups differed by a number of mutations, and no haplotypes were shared between populations from the different geographic regions. This suggests an ancient diversification of these haplogroups, and that long-distance seed dispersal was unlikely to have occurred during the Pleistocene when the Sunda Shelf was a contiguous landmass. Phylogenetic analysis of the haplotypes together with those found in other Shorea species showed that two haplogroups in S. curtisii appear in different positions of the phylogenetic tree. This could be explained by the persistence of ancestral polymorphisms or by ancient chloroplast capture. Low levels of genetic differentiation were found between populations within each geographic region. Signature of a bottleneck followed by demographic expansion was detected in the Malay Peninsula haplogroup. The presence of two distinct evolutionary lineages in the different regions suggests that they should be managed independently to conserve the major sources of genetic diversity in S. curtisii.

Nuclear and chloroplast DNA phylogeography reveals Pleistocene divergence and subsequent secondary contact of two genetic lineages of the tropical rainforest tree species Shorea leprosula (Dipterocarpaceae) in South‐East Asia

“…Similar phylogeographic patterns have been found for the same species using allozymes (Lee et al 2000) and AFLPs (Cao et al 2006). As we described in the Introduction, indications of the genetic uniqueness of Borneo populations in comparison with those of the other districts have also been observed in several other trees species, for example, Shorea curtisii (Kamiya et al 2012) and Shorea parvifolia (Iwanaga et al 2012), as well as various other terrestrial organisms distributed across Sundaland (for examples, see Fernando et al 2003;Hirai et al 2005;Steiper 2006;Wilting et al 2010). However, few previous studies have examined so many populations across such a large geographic range in Sundaland, and none have used two types of genetic markers simultaneously, at least in analyses of widespread tree species of the region.…”

“…As we described in the Introduction, indications of the genetic uniqueness of Borneo populations in comparison with those of the other districts have also been observed in several other trees species, for example, Shorea curtisii (Kamiya et al . ) and Shorea parvifolia (Iwanaga et al . ), as well as various other terrestrial organisms distributed across Sundaland (for examples, see Fernando et al .…”

“…Several authors have also investigated the genetic structure of common canopy trees in tropical rainforests of Sundaland, such as Shorea curtisii (Kamiya et al . ) and Shorea parvifolia (Iwanaga et al . ).…”

“…The latter hypothesis is supported by marked genetic divergences between the two areas observed in rainforest-dwelling mammals including elephants (Fernando et al 2003), gibbons (Hirai et al 2005), orangutans (Steiper 2006) and leopards (Wilting et al 2010). Several authors have also investigated the genetic structure of common canopy trees in tropical rainforests of Sundaland, such as Shorea curtisii (Kamiya et al 2012) and Shorea parvifolia (Iwanaga et al 2012). However, most of these earlier studies contained the following methodological shortcomings.…”

Dipterocarp Biology as a Window to the Understanding of Tropical Forest Structure: Where are we Looking Now?

“…Dipterocarps and their forests have been subject to considerable climate and edaphic changes associated with sea level changes in the Sunda region (Cannon et al 2009). Kamiya et al (2012) offer molecular evidence of regional genetic patterns likely arising from these changes, giving an example from Shorea xanthophylla. At the more local scale, Harata et al (2012) examine patterns of fine-scale spatial genetic structure and their relationship with pollinator size, fruit size, and adult tree density within single populations of selected species in Lambir, Sarawak.…”