| Abstract |
The complex geological history of the Aegean Archipelago where multiple geological events of land connections took place during the late Tertiary, have likely contributed to the diversification and distribution of many terrestrial animals. Connections offered opportunities for biological dispersal, while submergence of land bridges brought about distributive isolation among related taxa.
The well known geological history and the palaeogeography of the Aegean Archipelago offers the bases for many biogeographical and phylogenetic studies of terrestrial animals in the area. Scorpions are terrestrial animals, that show such high variability that they can be considered as appropriate model organisms for studies of biogeography, ecology and phylogeny. In the Aegean Archipelago there are three families of scorpions (Buthidae, Iuridae and
Euscorpiidae) that are not very well-studied. In this thesis, scorpions were used as tools for a comparative study on the adaptive and the evolutionary trends that appear in the Aegean Archipelago.
The three basic aims of this dissertation were: a) to make a review on the systematics and diversity of scorpions in the Aegean Archipelago, gathering all relevant literature, b) to survey the
ecological demands and the adaptive trends of scorpions in several habitats, and c) to approach the phylogeny/phylogeography of the three scorpion families of the Aegean Archipelago The bibliographic review showed that the following species are referred from Greece: Family Buthidae: Mesobuthus gibbosus. Family Iuridae: Calchas nordmanni and Iurus dufoureius. Family Euscorpiidae: Euscorpius italicus, E. naupliensis, E. sicanus, E. hadzii, E. koschewnikowi, E.
tergestinus and «E. carpathicus complex». Specifically in Crete there are three species: M. gibbosus, E. carpathicus candiota and I. dufoureius. The ecological survey revealed that E. c. candiota is more hydrophilic than M. gibbosus, so it appears in higher densities in places with higher humidity. Moreover, due to its cold hardiness, it
can survive at high altitudes (1650 m and 2100 m) and shift its activity towards autumn. By this adaptation, it probably avoids the bigger and more aggressive M. gibbosus, which might prey on it.
M. gibbosus is thermophylic and xerophylic, it appears in high densities in Crete and the peak of its activity is in summer. I. dufoureius prefers rather humid biotopes with dense vegetation. Its surface activity is very limited, which means either that its population is very small or that it is an obligate fossorial animal that comes on the surface of the ground very rarely. The reproductive period of all
three species is signaled by the peak of the activity of the males, which come on the surface searching for a mate. The gestation and the birth periods seem to vary among the species.
More specifically, the ecological study on M. gibbosus showed that the density of the active population is positively correlated with the environmental temperature, the mature individuals show low metabolic rhythms during the cold period, the immature individuals are active throughout the year, the seasonal activity of mature individuals is possibly synchronized with the food availability, while that of the immature is synchronized with the avoidance of intra-specific competition. The reproductive period is in summer, they show some kind of sociality and the shelter selection is based on the sex, the age class, the total body length and the month.
As for the differentiation and the adaptive trends of the genus Euscorpius, it has become clear that, among the Greek populations, the cretan population exhibits the highest number of trichobothria on the patella of the pincers (TPT) and the most pectinal teeth, while the population of Peloponnese has the less pectinal teeth and the less total body length, differences that indicate that the two populations may belong to different species. Additionally, the ability of the genus to survive in high altitudes suggests that it might have the ability of supercooling. Lastly, with the increase of the altitude, the number of TPT and the number of pectinal teeth (i.e. sense organs) as
well as the ratio P/M (i.e. food availability) increase too.
The phylogeography of the Greek scorpions showed that the phylogenetic patterns fit to the main palaeogeographic events of the Aegean Archipelago. Nevertheless, new data indicate some
possible land connections during the Miocene. More precisely, scorpions started to differentiate in the Aegean during the formation of the Mid-Aegean trench in the Middle Miocene. For the genus
Iurus, two clades were formed, the east and the west, which seem to correspond in two different species and not subspecies, as it was formerly believed. At M. gibbosus phylogenetic tree, there are
three clades that are grouped in island and mainland populations. Finally, the Euscorpius phylogeny revealed a completely different story from the one known to date: in some islands or group of islands the species were not the expected ones, based on literature, and this may be the case for some mainland populations as well. The most obvious example is the populations from Skyros island and Tinos-Andros island group that behave as completely isolated lineages. Resuming the phylogenetic analysis, the species of scorpions in the Aegean Archipelago could be reformed as following:
• Family Iuridae: Iurus asiaticus (east) και Iurus dufoureius (west)
• Family Buthidae: Mesobuthus sp. (Eastern Aegean islands) Mesobuthus gibbosus (rest of the Aegean region)
• Family Euscorpiidae: Euscorpius candiota (Crete, Kythira), Euscorpius naupliensis (Peloponnese, Zakynthos), Euscorpius sicanus (Prasonisi, Astypalaia, Central-Eastern Greece), Euscorpius sp1. (Skyros isl.) και Euscorpius sp2. (Eastern Aegean islands, Cyclades).
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