Comparative chloroplast DNA phylogeography of two tropical pioneer trees, Macaranga gigantea and Macaranga pearsonii (Euphorbiaceae)

Abstract

Macaranga (Euphorbiaceae) has received much ecological and evolutionary research attention as a genus that includes some of the most conspicuous pioneer trees of Southeast Asian tropical rainforests and because of its manifold associations with ants, including about 30 species that are obligate ant-plants (myrmecophytes). We used sequence data from three chloroplast DNA loci (ccmp5, ccmp6, atpB-rbcL) to assess phylogeographical patterns in species of Macaranga, section Pruinosae, sampled from various regions of Borneo and the Malay Peninsula. Fortynine chloroplast DNA haplotypes (HT) were identified among 768 specimens from five species, Macaranga gigantea (N= 329; 23 HT), Macaranga pearsonii (N=347; 21 HT), Macaranga puberula (N=24; 4 HT), Macaranga hosei (N= 48; 6 HT), and Macaranga pruinosa (N=20; 5 HT). Fortyone haplotypes were species-specific, whereas eight haplotypes were shared by two, three, or four species and occupied internal positions in a parsimony network. Population genetic parameters based on haplotype frequencies proved to be in a similar range in the non-myrmecophytic M. gigantea and in the ant-associated M. pearsonii, which have overlapping distributions in northern and eastern Borneo. A comparison of G ST and N ST values revealed a strong phylogeographic structure in both species, whereas colonization pathways suggested by the network topology were different. Both species exhibited similar levels of haplotypic diversity and moderate to high levels of population differentiation. There were no obvious indications for an influence of the symbiotic ant partners on the population structure of their host plants.

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

“…Molecular phylogeographic studies are also important to long-term conservation goals, because a unit of conservation within species is often defined by geographic patterns of genetic variation (Avise 2000). Several cpDNA phylogeographic studies for Southeast Asian tree genera (Lithocarpus and Macaranga) have been conducted so far, but are based on data from multiple species within a genus (Cannon & Manos 2003, Bänfer et al 2006, but see Guicking et al 2011). For example, phylogeographic structure of cpDNA haplotypes has been used to reconstruct migration routes of temperate tree species in Europe (e.g., Taberlet et al 1998) and North America (Soltis et al 1997).…”

“…and (2) to what extent did low sea levels during the Pleistocene facilitate migration between the Malay Peninsula and Borneo? Given that phylogeographic study of single species can be misleading due to the persistence of ancient DNA polymorphisms and occurrence of hybridization and introgression (Jakob & Blattner 2006, Guicking et al 2011, inclusion of data for a number of closely related species within Shorea could also be helpful for precisely identifying the origin of genetic diversity within S. curtisii. As these cpDNA regions have been recently used for the phylogenetic study of Shorea species (Tsumura et al 2011), we incorporated the data in the analysis to infer shared haplotypes between S. curtisii and the other species.…”

High gene flow in two thrips-pollinated South-East Asian pioneer trees: genetic diversity and population structure ofMacaranga hypoleucaandM. beccariana(Euphorbiaceae)

“…0.7 (Table ). Similar values were previously found in two species of Macaranga section Pruinosae , with one to six plastid DNA haplotypes per population and haplotype diversities of zero to 0.73 (Guicking et al ., ) and in M. winkleri Pax & K.Hoffm. (C. Baier, pers.…”

“…), which are unlikely to fly long distances. Dispersal of seeds is therefore expected to be locally restricted in Macaranga , and this is in concordance with the results of our studies (see also Guicking et al ., ).…”

“…Pollen flow, however, is likely to play an important role in maintaining genetic connectivity among established populations in pioneer trees, and a high efficiency of gene flow via pollen may explain low nuclear SSR‐based population structure as found in different Macaranga spp. (Guicking et al ., ; this study). Low population differention was also found in Cecropia obtusifolia Bertol.…”