Name: Ferreira S
Biodeserts supervisor: Brito JC
Co-supervisor: Phillip C. Watts, University of Oulu, Finland
Title: Evolutionary history, biogeography and conservation of endangered Odonates in the Mediterranean Basin
Institution: University of Porto
Status: Completed
Abstract
The Mediterranean Basin is a biodiversity hotspot: it is one of the world’s richest places in terms of animal and plant diversity, with a high levels of endemism. It is also an area that has experienced intense human development for thousands of years, leading to substantial impacts in the ecosystems. In particular, freshwater ecosystems are under great pressure as water resources are becoming particularly scarce and demand for water is continuously increasing. Dragonflies are a group of insects particularly vulnerable to impacts on freshwater ecosystems given their aquatic larvae. Of the 165 Mediterranean dragonflies species, 19% are classed as threatened and 16% are Near Threatened. This thesis aimed to contribute to a better understanding of the evolutionary history, biogeography and conservation status of selected endangered odonates in the Mediterranean Basin.
The development of Odonata phylogeographic studies has been hampered by the lack of a set of independent, polymorphic nuclear DNA markers. Therefore we started by developing new molecular markers to improve the resolution of phylogeographic studies of coenagrionids and other odonates. We followed an exon-primed, intron-crossing (EPIC) PCR strategy to develop five new, polymorphic nuclear DNA sequence loci (six distinct DNA fragments) for the southern damselfly Coenagrion mercuriale. Between three and five of these new markers could be PCR-amplified in five other species from the genus Coenagrion; one locus (PRMT) can be used in 26 other species of odonates that we examined, including species of Anisoptera belonging to the genus Onychogomphus. These new nuclear genetic markers provide a useful complement to the existing mitochondrial and nuclear loci for research in odonates.
Secondly, we explored the phylogenetic relationships within two genera in the Western Palaearctic: Cordulegaster and Onychogomphus to assess species/taxa distinctiveness and to frame endangered taxa in a phylogenetic context, clarifying the systematics of these groups. Our data support the existence of two major monophyletic groups corresponding to the traditional boltonii- and bidentata-groups. The validity of all described species was confirmed, but results on subspecies validity varied. There was no clear separation among the four subspecies of C. boltonii, with the exception of the populations of Cordulegaster boltonii algirica from North Africa. Similarly, no genetic differentiation was found between the two subspecies of C. bidentata, C. b. bidentata and C. b. sicilica. All species of Onychogomphus are genetically distinct, including a new taxon described as Onychogomphus boudoti Ferreira, 2014.
We explore the phylogeographic history of Coenagrion mercuriale based on mitochondrial and the new nuclear DNA markers. We combined genetic analyses with ecological niche-based modelling to understand the genetic diversity of C. mercuriale along its distribution area and how past climatic oscillations affect the distribution of this species to identify Evolutionary Conservation Units within this taxon. Three deep lineages were identified: an Italian, a North African, and a Western European, which ranges from Iberian Peninsula to United Kingdom and Germany. Projections to past conditions predicted that stable areas of climatic suitability was restricted to six isolated areas: one in Italy, two in Morocco and three in the Western Europe. No gene flow was found between the three lineages. Higher genetic diversity across markers was found in the Western Europe and the North African lineages, with higher values in Western Europe for mtDNA and one nuclear marker and in North Africa for two of the three nuclear markers.
Finally, we investigated the current status of North African populations of two Coenagrion species. We updated information on extinct and extant populations of Coenagrion mercuriale in North Africa and characterized the localities with regard to their topography, climate and anthropogenic use (anthrome). These C. mercuriale populations are being lost and this damselfly is experiencing a range contraction. This species, which occupied predominantly areas of high value for human settlement, is now mainly restricted to high altitudes. Nevertheless, the extant populations remain under threat of extinction due to increasing demand for water, changes in agricultural practices and land conversion. North African populations of Coenagrion puella, a species even rarer than C. mercuriale in North Africa are genetically distinct from their European counterparts (at both mitochondrial and nuclear genetic markers), with lack of shared haplotypes between individuals from the two continents. These results re-invigorate the debate on the validity of the North African endemic C. puella kocheri, and we propose that the two lineages of C. puella should be managed as distinct molecular operational taxonomic units (MOTUs).