The Zoogeographic Regions of the Aegean Sea: a Multi-Taxon Approach
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17_Layout 1 6/9/2018 11:30 ππ Page 279 The Zoogeographic Regions of the Aegean Sea: A Multi-Taxon Approach Kostas A. Triantis1*, Kostas Kougioumoutzis1*, Anastasios Legakis1, Ioannis Anastasiou1, Pavlos Andriopoulos1, Christos Georgiadis1, Petros Lymberakis2, Anthi Oikonomou3, Nikos Probonas4, Kostas Proios1, Vasiliki Spaneli2, Stylianos M. Simaiakis2, Apostolos Trichas2, Panayiotis Trigas5, Katerina Vardinoyannis2 and Spyros Sfenthourakis6 1Faculty of Biology, National & Kapodistrian University of Athens, Panepistimiopolis, 15703 Athens, Greece. Emails: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected] 2Natural History Museum of Crete, University of Crete, Knossou Ave. 71409, Irakleio, Crete, Greece. Emails: [email protected]; [email protected]; [email protected]; [email protected]; [email protected] 3Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavyssos, Greece. Email: [email protected] 440 Ekklision 12, Peristeri, Attiki, 12134, Greece. Email: [email protected] 5Faculty of Crop Science, Agricultural University of Athens, Iera Odos, GR-118 55, Athens, Greece. Email: [email protected]; 6Department of Biological Sciences, University of Cyprus, Panepistimiou Ave. 1, 2109, Aglantzia, Nicosia, Cyprus. Email: [email protected] *equal contribution ABSTRACT The Aegean archipelago is a typical archipelago of continental islands which stands at the cross- roads of Europe, Asia and Africa. Herein we present one of the few global studies of bioregional- ization,i.e., the process of identifying, delimiting and naming biogeographical regions, based on eight animal taxa, namely ants (Formicidae), land birds, reptiles and amphibians, land snails, ter- restrial isopods (Oniscidea), tenebrionid beetles (Tenebrionidae), Lepidoptera, Orthoptera and centipedes (Chilopoda). Dispersal ability, ecological requirements, and endemism seem to shape the major biogeographical regions identified. Further insights on the processes establishing biodi- versity patterns can be gained by such multi-taxon approaches. INTRODUCTION Already in the 19th century, naturalists such as von Humboldt and Bonpland (1807), Sclater (1858) and Wallace (1876) had noticed that the globe’s biota can be divided into a number of more or less distinct geographical units. Wallace (1876) used existing knowledge of his time on the distribution and taxonomic relationships of vertebrate families (Sclater, 1858), and divided the world into six ter- 279 17_Layout 1 6/9/2018 11:30 ππ Page 280 280 The Zoogeographic Regions of the Aegean Sea: A Multi-Taxon Approach restrial zoogeographic units and further recog- cios, & Geist, 2016; Borregaard et al., 2017; nised four subregions in each major unit. His Whittaker et al., 2017). was the first map of global terrestrial zoogeo- However, the vast majority of true geograph- graphic regions (see Holt et al., 2013). The iden- ical islands are not oceanic but continental-shelf tification of biogeographical regions (geographi- islands. Considering only those with an area cally distinct assemblages of species and com- larger than 1 km2, they represent a 27% of the munities) is a critical step towards unveiling total number of islands worldwide (Weigelt, processes establishing species diversity and un- Jetz, & Kreft, 2013). Although an accurate esti- derstanding the origins and relationships be- mation of all the geographical islands of the tween distinct faunal/floristic assemblages (e.g. world is not available, oceanic islands represent Kreft & Jetz, 2010; Holt et al., 2013; Vilhena & an even smaller fraction according to the crude Antonelli, 2015; Ficetola, Mazel, & Thuiller, estimation of ca. 1 million islands in the globe 2017). The development and integration of sev- by Fernández-Palacios (2011). eral multivariate hierarchical and network ap- The Aegean Sea hosts a typical archipelago of proaches (e.g., Kreft & Jetz, 2010; Leprieur & continental-shelf islands that has long fascinated Oikonomou, 2014; Vilhena & Antonelli, 2015; biogeographers (e.g., Rechinger, 1943; Rechinger Edler, Guedes, Zizka, Rosvall, & Antonelli, 2017; & Rechinger-Moser, 1951; Wettstein, 1953; Rune- Ficetola et al., 2017), in conjunction with the in- mark, 1970, 1971; Greuter, 1975; Mylonas, 1982, creasing availability of species distribution data, 1984; Sfenthourakis, 1996a,b; Strid, 1996, 2016; has sparkled a new interest in biogeographical Sfenthourakis, Giokas, & Mylonas, 1999; Fattorini, research at continental and global scales (Kreft 2002; Hausdorf & Hennig, 2005; Simaiakis, Minelli & Jetz, 2010; Holt et al., 2013; Ficetola et al., & Mylonas, 2005; Comes, Tribsch, & Bittkau, 2017) but also at local ones (Carstensen et al., 2008; Bittkau & Comes, 2009; Papadopoulou et 2012; Kougioumoutzis, Simaiakis, & Tiniakou, al., 2011; Triantis & Sfenthourakis, 2012; Simaiakis 2014; Oikonomou, Leprieur, Leonardos, 2014; et al., 2012, 2017; Kougioumoutzis et al., 2014, Kougioumoutzis et al., 2017). 2017; Poulakakis et al., 2015; Sfenthourakis & Tri- Islands have been the focal research area for antis, 2017; Jaros, Tribsch, & Comes, 2017), since several biogeographical phenomena and island it constitutes one of the largest archipelagos in research has culminated in the development of the world, with more than 7,000 islands and islets essential contributions to our understanding of lying at the crossroads of three different biogeo- key ecological and evolutionary processes (e.g., graphical regions, namely Europe, Asia and Africa immigration, extinction, turnover, speciation, (Triantis & Mylonas, 2009; Sfenthourakis & Tri- taxon cycles) and biodiversity patterns. Islands antis, 2017). Its high environmental and topo- constitute ideal study systems due to their com- graphical heterogeneity, complex palaeogeo- paratively small size, distinct boundaries and, graphical history, as well as high diversity and en- usually, less complex biota (Whittaker & Fernán- demism, render it an ideal stage for biodiversity dez-Palacios, 2007; Whittaker, Fernández-Pala- and biogeographical studies (Triantis & Mylonas, cios, Matthews, Borregaard, & Triantis, 2017). 2009; Trigas, Panitsa, & Tsiftsis, 2013; Sfen- Today, the focus on island research is stronger thourakis & Triantis, 2017). Recently, based on the than ever (Warren et al., 2015) even though in- distribution of 1,498 plants from 59 islands, Kou- sular faunas are considered species-poor and gioumoutzis et al. (2017) identified six different being on the receiver’s end of the colonization biogeographical areas for plants, which corre- process (e.g. MacArthur & Wilson, 1967; but spond well to the Aegean’s palaeogeography from see Bellemain & Ricklefs, 2008). In this context, the middle Miocene to the end of the Pleistocene oceanic islands and archipelagos have drawn (Figure 1). However, a similar approach for ani- much more attention compared to continental mals is still missing. island systems (e.g., Whittaker, Triantis, & Ladle, Herein we present the first study on biore- 2008; Triantis, Economo, Guilhaumon, & Rick- gionalization (the process of identifying, delimit- lefs, 2015; Triantis, Whittaker, Fernández-Pala- ing and naming biogeographical regions) of the 17_Layout 1 6/9/2018 11:30 ππ Page 281 281 The Zoogeographic Regions of the Aegean Sea: A Multi-Taxon Approach FIGURE 1 ¡ The major phytogeographical regions of the Aegean Sea based on Kougioumoutzis et al. (2017). Green: South Mainland & Islands, Fuchsia: North Mainland & Islands, Orange: North-Eastern Aegean, Blue: Central Aegean, Red: Crete, Yellow: South-Eastern Aegean. Aegean Sea based on several animal taxa. This is main distributional and palaeogeographical amongst the few global studies incorporating da- barriers reign supreme in the Aegean archipela- ta from multiple taxa, both vertebrates and in- go (Figure 2, see the review by Poulakakis et al., vertebrates, encompassing a variety of ecologi- 2015; Sakellariou & Galanidou, 2016; Sakellari- cal requirements and evolutionary histories. ou et al., 2017; and Fassoulas, present volume): (1) the formation of the Mid-Aegean Trench (MAT), (2) the isolation of Crete from Pelopon- THE MAJOR PALAEOGEOGRAPHICAL nisos after the Messinian Salinity Crisis, and (3) BARRIERS OF THE AEGEAN SEA the separation of Kasos and Karpathos from Ro- The palaeogeography of the Aegean has largely dos in the Pliocene. Most important in terms of shaped current biodiversity patterns (Greuter, geographical and temporal extent is the forma- 1975; Mylonas, 1982, 1984; Sfenthourakis, tion of a sea barrier (the MAT), which initiated 1996a; Comes et al., 2008; Triantis & Mylonas, at the end of middle Miocene (12 Ma) and was 2009; Lymberakis & Poulakakis, 2010; fully completed in the late Miocene (10–9 Ma). Poulakakis et al., 2015; Kougioumoutzis et al., The opening of the MAT started with sea intru- 2017; Sfenthourakis & Triantis, 2017). Three- sion separating Crete from the Karpathos’ is- 17_Layout 1 6/9/2018 11:30 ππ Page 282 282 The Zoogeographic Regions of the Aegean Sea: A Multi-Taxon Approach FIGURE 2 ¡ The major geological barriers in the Aegean Sea, based on Lymberakis & Poulakakis (2010) (see also Poulakakis et al., 2015) (numbers in millions of years). land complex at 12 Mya. This initial split then METHODS bifurcated, forming the N–S axis of the MAT that reached up to the modern island of Thasos Sources of data (9 Ma) and separated the Cyclades from the We recorded the