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Myrmekophyten sind standig von Ameisen besiedelte Pflanzen. Die Ameisen erhalten eine Wohnstatt und Futter von der Pflanze, im Gegenzug beschutzen sie ihren Wirt vor Herbivoren und pflanzlichen Konkurrenten. Die vielfaltigen Beziehungen zwischen tropischen Pionierbaumen der Gattung Macaranga und ihren Partnerameisen der Gattung Crematogaster stellen die bedeutendste und artenreichste mutualistische Ameisen-Pflanzen-Assoziation der Altwelttropen dar. Mit Hilfe vergleichender DNA-Sequenzierung und molekularer Marker-Technologien analysieren wir die Verwandtschaftsverhaltnisse innerhalb der etwa 30 myrmekophytischen Macaranga-Arten und ihre Co-Evolution mit Ameisen sowie die Populationsgenetik und historische Biogeografie einzelner Artengruppen. Ausmas und Strukturierung der genetischen Diversitat dieser Pionierbaumarten zeigen interessante Korrelationen mit ihrer Reproduktionsbiologie und der Besiedlung von zunehmend fragmentierten Pionierhabitaten im tropischen Regenwald. Molecular systematic studies in Southeast Asian ant-plants Myrmecophytes are plants that are permanently inhabited by ants. They provide nesting space and feed their partners, whereas the ants protect their hosts from herbivores and competitors such as climbers and lianas. The manifold relationships between tropical pioneer trees of the genus Macaranga and their partner ants of the genus Crematogaster constitute the most important and species-rich mutualistic ant-plant relationship of the Paleotropics. We use comparative DNA sequencing and molecular marker technologies to evaluate phylogenetic relationships among the about 30 myrmecophytic Macaranga species as well as their co-evolution with ants. We also study the population genetics and historical biogeography of particular Macaranga species groups. Patterns of genetic diversity and differentiation in these pioneer tree species show interesting correlations with their reproductive biology and with characteristics of the increasingly fragmented pioneer habitats in the rainforests of Sundaland.

In the present study, we use mtDNA sequence data (cyt b gene) in combination with nuclear DNA sequences (C-mos, Rag2 genes, R35 intron), nuclear genomic fingerprints (ISSR) and morphological data to reveal species diversity within the Southeast Asian leaf turtle genus Cyclemys, a morphologically difficult group comprising cryptic species. Two morphologically distinct major groupings exist, a yellow-bellied species group with three taxa (Cyclemys atripons, C. dentata, C. pulchristriata) and a dark-bellied species group. The latter contains besides the morphologically variable C. oldhamii three additional new species (C. enigmatica n. sp., C. fusca n. sp., C. gemeli n. sp.). According to mtDNA data, C. fusca and C. gemeli constitute with high support the sister group of a clade comprising all other species, indicating that the dark-bellied species are not monophyletic, despite morphological similarity. mtDNA sequences of C. enigmatica, being highly distinct in nuclear genomic markers, do not differ from the sympatric C. dentata, suggesting that the original mitochondrial genome of C. enigmatica was lost due to introgressive hybridization. Morphological discrimination of Cyclemys species is possible using multivariate methods. However, gross morphology of most dark-bellied species on the one hand and of C. atripons and C. pulchristriata on the other is so similar that reliable species determination is only possible when genetic markers are used. The high diversity within Cyclemys requires revision of the IUCN Red List Categories for leaf turtles because the former assessment was based on the wrong assumption that in the entire range of the genus occurs only a single species.

We developed primer sequences for five polymorphic microsatellite loci in the tropical ant-plant genus Macaranga (Euphorbiaceae). Population genetic parameters were determined on the basis of 30 individuals from each of two Macaranga species in Borneo. Allele numbers per locus ranged from three to 13. Expected and observed heterozygosities ranged from 0.160 to 0.850 and from 0.130 to 0.700, respectively. Four of the five primer pairs cross-amplify polymorphic PCR products in a wide range of Macaranga species.