| Abstract |
The genus Phlebotomus (Diptera: Psychodidae) belongs to the subfamily of
Phlebotominae, which comprises a group of small insects, known as sand flies. Sand flies
are small, hairy dipteran insects that feed on blood during their breeding season. They
are medically important insects, as they are capable of transmitting Leishmania parasites,
which cause canine and human leishmaniases. Sand flies are found mainly in tropical and
subtropical regions, while several species have wide geographical distributions,
occupying European, African and Asiatic regions. They are also nocturnal insects and
their life cycle is regulated by humidity and temperature.
Worldwide, there are over than 800 recognised sand fly species. Their systematic
classification is the subject of several studies, since there is not any universal
classification system that is acceptable to all researchers. The most widely used
systematic classification, places sand flies into 6 genera (3 in the New World and 3 in the
Old World). According to this classification, the genus Phlebotomus is present only in the
Old World and includes 14 subgenera. Six of them are found in Greece. To date, 14 sand
fly species are present in Greece, 11 belonging to the genus Phlebotomus and 3 to the
genus Sergentomyia. Eight of them are transmitting or are suspected to transmit
Leishmania parasites. Most of the Phlebotomus species present in Greece, have wide
geographical distributions, occupying Mediterranean, African or Asiatic regions. On the
contrary, P. (Adlerius) creticus and P. (Transphlebotomus) killicki are found only in the
Aegean region and the eastern Mediterranean respectively.
The present dissertation focuses on the local species of the genus Phlebotomus,
that were collected from 12 Greek Aegean islands. These islands are located between the
Greek mainland, Turkey and north Africa. The Greek Aegean Islands provide an
interesting area for phylogenetic and phylogeographic studies because of their
topography and geological history. The Aegean archipelago consists of many islands and
islets with great heterogeneity and a wide variety of properties. Their palaeogeographical
history included events such as the Messinian salinity crisis, the Aegean Barrier and the
glacial and interglacial periods.
Comprehensive molecular and morphological studies on the sand fly fauna of
Greece are limited, and most existing research (using molecular or morphological
techniques) is focused either on a limited number of species or on a limited dataset (few
genetic markers, or few morphological characters). Thus, the present dissertation aimed
to study the local sand fly species of the Greek Aegean islands, investigating their
phylogenetic relationships and evolutionary history through molecular and
morphological analyses. To accomplish these, phylogenetic, phylogeographic and
morphological analyses were performed on 6 genetic loci (2 mitochondrial and 4 nuclear
loci), and 91 morphological characters (44 male characters and 47 female characters).
Our analyses revealed for the first time the presence of P. (Larroussius) cf. major
and P.(Paraphlebotomus) sergenti in the Greek Aegean islands. The phylogenetic analyses revealed 3 major clades. The first clade included P. (Artemievus) alexandri, P.
(Phlebotomus) papatasi, P. (Paraphlebotomus) sergenti and P. (Paraphlebotomus) similis.
The other 2 clades appeared more closely related to each other. The second clade
included the representatives of the subgenera Transphlebotomus and Adlerius, and the
third clade included the representatives of the subgenus Larroussius. The mtDNA and
nDNA gene trees indicated a plausible mitochondrial introgression (most likely through
hybridization) between the closely related species of the P. (Larroussius) major complex.
Phlebotomus (Adlerius) balcanicus was identified as the sister species of P. (Adlerius)
creticus, however, in the species delimitation analysis, P. (Adlerius) balcanicus was not
estimated as a distinct species, probably due to the lack of nuclear data.
From a palaeogeographical viewpoint, the major driving force that shaped the
biogeographic history of the studied local Phlebotomus species seems to be the dispersal
that started in the Oligocene epoch. Several speciation events occurred at the end of
Miocene and the Plio-Pleistocene, including multiple dispersal events of Asiatic origin.
The Messinian salinity crisis seems to have played important role in the divergence of the
lineages of P. (Larroussius) perniciosus and P. (Larroussius) tobbi. The bimodal
Mediterranean climate was identified as the main driver for the diversification of the P.
(Paraphlebotomus) sergenti and P. (Paraphlebotomus) similis lineages. Finally, the glacial
and interglacial periods were identified as key drivers for the diversification of the P.
(Larroussius) major complex, as well as the lineages of P. (Adlerius) balcanicus and P.
(Adlerius) creticus.
The interspecific and intraspecific morphological diversity in the local sand fly
species and populations, was highlighted through the morphological analyses. The
interspecific diversity that was found in the local studied species was mostly in
agreement with that in the identification keys and previous morphological research
studies. Phlebotomus(Larroussius) cf. major had significant morphological differentiation
(in most morphological characters) from its sister species P. (Larroussius) neglectus. On
the other hand, the closely related species P. (Paraphlebotomus) sergenti and P.
(Paraphlebotomus) similis had minor morphological differences, hence, their
morphological separation remained extremely difficult. Phlebotomus (Larroussius)
neglectus revealed to have a strong intraspecific morphological diversity, since the sand
fly populations in Ikaria and Andros presented significant differentiation from (in most
morphological characters) all the other populations.
In conclusion, the present study highlights the importance of the Greek Aegean
islands, however, it also stresses the need for further sampling and additional
morphological and molecular analyses. Future studies should include a more
comprehensive phylogeny of the entire genus, incorporating more sand fly species and
various populations of each species. Finally, the establishment of new updated
identification keys should be targeted in future studies, incorporating new taxonomic
characters and species
|
Collections
