Ann. Zool. Fennici 50: 247–255 ISSN 0003-455X (print), ISSN 1797-2450 (online) Helsinki 2013 © Finnish Zoological and Botanical Publishing Board 2013 Influence of climate on segment number in Geophilus flavus, a centipede species inhabiting Sognefjord in western Norway Stylianos M. Simaiakis1,2,*, Per Djursvoll3 & Robert Bergersen4 1) Department of Biological Sciences, University of Cyprus, P.O. Box 20537, CY-1678 Nicosia, Cyprus (*corresponding author’s e-mails: [email protected] & [email protected]) 2) Natural History Museum of Crete, University of Crete, Knossos Av., PoBox 2208, GR-71409 Heraklion, Greece 3) University Museum of Bergen, Realfagbygget, NO-5020 Bergen, Norway 4) Tromsø Museum, University of Tromsø, NO-9037 Tromsø, Norway Received 12 Oct. 2012, final version received 2 Feb. 2013, accepted 1 Mar. 2013 Simaiakis, S. M., Djursvoll, P. & Bergersen, R. 2013: Influence of climate on segment number in Geophilus flavus, a centipede species inhabiting Sognefjord in western Norway. — Ann. Zool. Fennici 50: 247–255. Since in laboratory experiments a relationship between segment number and tempera- ture in geophilomorph centipedes has been proven, we suggest that climatic variation in nature could have a direct effect on segment number. To address this hypothesis we examine the way in which local climatic factors in Sognefjord — air temperature and precipitation both changing along a longitudinal gradient — exert their effect on seg- ment number in Geophilus flavus. Changes in G. flavus segment number along the cli- matic gradient are similar to that found in previous laboratory experiments with Striga- mia maritima, but are even more pronounced. In G. flavus, a 1.5 difference in the mean segment number is found in populations that occur in Sognefjord along a temperature gradient of only about 1.4 °C. In contrast, several degrees centigrade were required to produce a similar increase in the mean segment number in laboratory experiments involvingP S. maritimaR . E P R I N T Introduction an odd number of leg-bearing segments (LBS). There have been numerous studies presenting There are five extant orders of centipedes: Scu- segment numbers in geophilomorphs (Bergsoe tigeromorpha, Lithobiomorpha and Craterostig- & Meinert 1866, Stuxberg 1871, Attems 1929, momorpha with 15 leg pairs, Scolopendromorpha Hammer 1931), while some others focused on the with 21 or 23 leg pairs (although in Scolopen- geographic variation in segment numbers (Lewis dropsis duplicata also other numbers have been 1985, Horneland & Meidell 1986, Arthur 1999, found, see Minelli et al. 2009), and Geophilo- Arthur & Kettle 2001, Simaiakis & Mylonas morpha whose numbers of leg pairs vary widely: 2006). Only recently, scientists have started to from 27 to 191 (Minelli & Bortoletto 1988, seek the mechanism of segmentation in geophi- Minelli et al. 2000). All adult centipedes have lomorphs (Arthur & Farrow 1999, Minelli 2000, 248 Simaiakis et al. • ANN. ZOOL. FeNNIcI Vol. 50 2001, Kettle et al. 2003, Chipman et al. 2004a, eastern Mediterranean area (Simaiakis & Mylo- Chipman & Akam 2008, Brena & Akam 2012) nas 2006, Simaiakis 2009). However, none of and study the evolution of body patterns (Minelli these studies attempted to correlate local mete- et al. 2010) to show that a double-segment perio- orological variables with segment numbers to dicity was involved in segment generation (Chip- support the case for the existence of tempera- man et al. 2004b). Kettle and Arthur (2000) were ture-dependent plasticity and related geographic the first to find out that number of leg pairs varies clines within geophilomorph species. Since we with latitude across the east coast of Britain, now have strong laboratory evidence for the in accordance with the proposal that body size effect of temperature on the number of leg increases with decreasing latitude (specimens pairs in S. maritima (Kettle et al. 2003, Vedel from colder regions tend to be smaller and with et al. 2008, 2009, 2010) we decided to carry out fewer trunk segments than those from warmer a study in a geographical region (Sognefjord) regions, see Eason 1979, Hayden et al. 2012). where climatic data are available to find the Up to now, Strigamia maritima is the main effect of temperature and precipitation on LBS model species for studies of segmentation and numbers in a geophilomorph species. Since in segment number variation (Kettle et al. 2003, embryos LBS numbers increase lineary with Vedel et al. 2010, Brena & Akam 2012, Hayden increasing temperature (for more details see et al. 2012). Previous works have shown that this Vedel et al. 2008), we may expect changes in variation has both environmental and genetic climate parameters towards the inner part of the bases (for further discussion see Vedel et al. fjord to explain, at least partially, the variation in 2008, 2009). Moreover, the results of laboratory LBS number in G. flavus. experiments presented to date demonstrate that in S. maritima, temperature affects the number of LBS that develop during embryogenesis (Vedel Material and methods et al. 2010). Therefore, we hypotesize that in geophilomorphs in nature, temperature variation Sample collection in Sognefjord — not necessarily resulting from a latitudinal cline — during early embryogenesis, could have Individuals of Geophilus flavus can be easily a significant effect on segment number (see also found in Sognefjord at low altitudes along cer- Vedel et al. 2010). To proove this hypothesis, tain parts of the fjord (e.g., narrow valleys at the adequate climatic data from a particular area heads of its branches, close to the sea shore, and would be necessary. There are several reasons along river banks). For the purpose of this study, why Sognefjord — located in Sogn og Fjor- 421 adult specimens were collected between 31 dane county (61°N, 5°–8°E) — was selected to May and 25 August 2009 from eight location be a region to study geographic variation in S. in the fjord (see Fig. 1). All the specimens were maritima segment number: (i) rich network of collected by hand, preserved in 75% ethanol, permanent and temporaryP Rmeteorological E sta- Pidentified R according I toN the descriptiveT key in tions across the fjord (Norwegian Meteorologi- Andersson et al. (2005), and deposited in the cal Institute, Utaaker & Skaar 1970), (ii) long University Museum of Bergen. While collect- west–east profile from the open Norwegian Sea ing the animals between 31 May and 20 June, to the central parts of southern Norway (Utaaker we observed many brood cavities with females & Skaar 1970), and (iii) topography causing coiled around their eggs (Fig. 2). significant differences in local climate (e.g., The total number of specimens collected as temperature, precipitation) over short distances well as other data used in this study are pre- (Utaaker 1980). sented in Table 1. Previous studies mainly dealt with segment number variation along a wide or narrow geo- graphical gradient either in the northwestern Climate data Europe (Kettle & Arthur 2000, Arthur & Kettle 2001, Simaiakis et al. 2010) or in the north- To obtain the climate data for the study sites ANN. ZOOL. FeNNIcI Vol. 50 • Effect of climate on segment number in Geophilus flavus 249 Fig. 1. Sampling sites in Sognefjord (Sogn og Fjordane district) in west- ern Norway. Lavik (La), Vadheim (Va), Høyanger (Ho), Balestrand (Ba), Leikanger (Le), Sogndal (So), Kaupanger (Ka) and Årdal (Ar). we used the climate database of the Norwegian Meteorological Institute accessible via the free web portal “eKlima”. The database contains cli- mate data from numerous weather stations in Sognefjord since 1931 to present. In addition, detailed climatic tables for the years 1964–1966 were obtained from Utaaker and Skaar (1970). In this study, we used mean monthly normal values of temperature (°C) and sum monthly normal values of precipitation (mm) for the period 1931–1990 from meteorological stations located close to the sampling sites (see Appen- dix). Since the climate data for Kaupanger (site 7, see Appendix) were insufficient, we used the Fig. 2. Female Geophilus flavus with eggs in a brood cavity in situ. This photo was taken at the collection site data from the Gaupne meteorological station near Vadheim, on 20 June 2009. (Norwegian Meteorological Institute), and tem- porary meteorological stations which operated between 1964 and 1966 (Utaaker & Skaar 1970) The long-term meteorological data indicate close to Kaupanger and almost at the same longi- that the climate in the fjord changes from strictly tudinal coordinate. oceanic in its outer part (6.9 °C mean annual air Table 1. Numbers (n) of female and male Geophilus flavus collected from each site in Sognefjord, numbers of specimens with particular leg-bearing-segment (LBS) numbers (49 to 57), and mean LBS in females and males. The sites are arrangedP from west R (Lavik) to eastE (Årdal). P R I N T Site in Sognefjord Sampling date Lat. Long. Females Males (°N) (°e) LBS LBS n 53 55 57 mean n 49 51 53 55 mean 1. Lavik (La) 31 May 2009 61.105 5.505 36 15 18 3 54.33 48 2 25 21 0 51.79 2. Vadheim (Va) 20 June 2009 61.212 5.838 32 16 16 0 54.00 33 0 26 7 0 51.42 3. Høyanger (Ho) 20 June 2009 61.219 6.074 21 5 15 1 54.62 16 1 3 12 0 52.38 4. Balestrand (Ba) 25 Aug. 2009 61.226 6.485 11 1 7 3 55.36 14 0 0 14 0 53.00 5. Leikanger (Le) 25 Aug. 2009 61.185 6.808 24 1 19 4 55.25 28 0 7 20 1 52.57 6. Sogndal (So) 20 Aug. 2009 61.231 7.086 17 2 12 3 55.12 37 0 13 21 3 52.46 7. Kaupanger (Ka) 20 Aug. 2009 61.177 7.266 26 3 15 8 55.38 22 0 1 19 2 53.09 8.