The goal of this project is to investigate species diversity and relationships in a group of ants, Crematogaster, on the island of Madagascar. These are diverse and dominant arboreal ants with a worldwide distribution for which accurate estimates of the number of species are much-needed but notoriously problematic. This study uses morphological and genetic methods to identify species and to describe any new species of these ants in Madagascar and to investigate their relatedness to other members of the group that are found in different geographical regions.
Madagascar is one of the world?s biodiversity hotspots, harboring a unique flora and fauna, including the charismatic lemurs and plants such as the Madagascar periwinkle, valued both as an ornamental and a source of anti-cancer drugs. This research contributes significantly to understanding the unique evolutionary history of Malagasy plants and animals and delivers complete distribution records and species estimates that are needed as a basis for all further ecological and conservation measures. Broad dissemination of data is achieved through the development of web-based species identification tools, and through the education of local students and resource management authorities in Madagascar. This study thereby supports ongoing efforts to define areas for the expansion of the protected area network in Madagascar, and further enhances the local research capacity through educational activities.
The goal of this project was to investigate relationships and species diversity in a group of ants, the genus Crematogaster. These are diverse and dominant arboreal ants with a worldwide distribution for which accurate estimates of diversity and genealogy are much-needed but notoriously problematic. This study used genetic methods to investigate relationships within this group of ants worldwide, with a special interest placed on the colonization history of the island of Madagascar. Furthermore, both morphology (i.e., external anatomical characteristics) and DNA were used to delimit and describe the species of these ants in Madagascar, in order to provide diversity and distribution data to conservation policy makers and identification tools to local Madagascar researchers. Our genetic data and evolutionary phylogenetic analyses lend strong support for the existence of three major groups within Crematogaster ants. Molecular clock dating and analysis of biogeographic patterns further suggest that the common ancestor of Crematogaster evolved in South-East Asia about 40-45 million years ago, and that the three major groups also originated in this region around 24-30 million years ago (late Oligocene to early Miocene). The data indicate that these ants first dispersed out of South-East Asia to Africa 22-30 million years ago. The global distribution of Crematogaster was achieved by subsequent colonizations of all major landmasses by two of the three major groups within Crematogaster. The third group diversified exclusively in South-East Asia and Australia. The Madagascar Crematogaster represent eight distinct groupings, and thus eight independent dispersal events to Madagascar are inferred, mostly from mainland Africa about 5-10 million years ago. We found the previous internal classification of Crematogaster, consisting of 15 subgroupings, to not adequately represent the relationships within the genus, and therefore we revised it to reflect the inferred evolutionary history. This newly erected classification can now function as a framework for further in-depth research studies on these ants. Morphological and molecular work focusing on the Madagascar species revealed thirteen new species of Crematogaster, and aided in resolving a number of nomenclatural problems. A pattern emerging from our research on the species-level taxonomy of Crematogaster is the occurrence of one or two widespread species per species-group that are morphologically highly variable and have thus been historically 'overnamed'. In contrast, we discovered a number of new species in each species-group that have more restricted, and locally endemic distributions. A short field project in Madagascar further concentrated on the dissemination of our research results through the education of local university students in ant collecting and identification methods. Our project constitutes the most extensive biogeographical study on a globally distributed group of ants to date, and is thus significant in estimating for the first time the historical spread of such a cosmopolitan genus. Understanding the history of ant dispersal becomes important in particular when invasive ant species are concerned, such as the red imported fire ant or the Argentine ant. Madagascar is one of the world’s foremost biodiversity hotspots, harboring a unique flora and fauna, including the charismatic lemurs and plants such as the Madagascar periwinkle, valued both as an ornamental and a source of anti-cancer drugs. This research contributed significantly to our understanding of the unique evolutionary history of the Malagasy plants and animals, and it delivers complete distribution records and species estimates that are needed as a basis for all further ecological and conservation measures. This study thereby supported ongoing efforts to define areas for the expansion of the protected area network in Madagascar. Through our educational activities we have further contributed to the enhancement of local research capacity in Madagascar.
