TEMPORAL AND GEOGRAPHICAL VARIATION OF SHREWS OF THE SICILIAN-MALTESE ARCHIPELAGO SINCE THE PLEISTOCENE R Hutterer To cite this version: R Hutterer. TEMPORAL AND GEOGRAPHICAL VARIATION OF SHREWS OF THE SICILIAN- MALTESE ARCHIPELAGO SINCE THE PLEISTOCENE. Vie et Milieu / Life & Environment, Observatoire Océanologique - Laboratoire Arago, 1990, pp.213-216. hal-03036099 HAL Id: hal-03036099 https://hal.archives-ouvertes.fr/hal-03036099 Submitted on 2 Dec 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. VIE MILIEU, 1990, 40 (2/3) : 213-217 TEMPORAL AND GEOGRAPHICAL VARIATION OF SHREWS OF THE SICILIAN-MALTESE ARCHIPELAGO SINCE THE PLEISTOCENE R. HUTTERER Muséum Alexander Koenig, Adenauerallee 150-164, D 5300 Bonn 1, W. Germany MAMMALIA ABSTRACT - A synthesis is given on the temporal and geographical size variation SORICIDAE of the shrew Crocidura sicula Miller, 1901. It is shown that Pleistocene popula- CROCIDURA tions from Sicily and Malta, described as a separate species by Kotsakis (1986), SICILY MALTA have evolved to the present-day populations of Sicily, the Egadi Islands, and Gozo. SIZE VARIATION Due to sea level changes, probably ail thèse islands were temporarily connected EVOLUTION by land-bridges during the Pleistocene. Subséquent geographical isolation led to the évolution of at least three morphologically distinct extant populations. MAMMALIA RESUME - Une synthèse des variations de taille temporelles et géographiques SORICIDAE de l'espèce Crocidura sicula Miller, 1901, depuis le Pléistocène, est présentée. CROCIDURA Les populations de Sicile et de Malte, décrites en tant qu'espèce séparée par Kot- SICILE MALTE sakis (1986) ont évolué vers les populations actuelles de Sicile, des îles Egadiennes VARIATION et de Gozo. Ces îles ont probablement été reliées entre elles pendant le Pléistocène; ÉVOLUTION par suite des variations du niveau marin et de l'isolement géographique qui en résulte, l'évolution conduit à au moins trois populations contemporaines, distinctes par leur morphologie. INTRODUCTION MATERIAL AND METHODS The shrews of the Mediterranean Islands have Approximately 3105 fossil and 86 extant spéci- been subject of contradictory taxonomic opinions mens of Crocidura from the Sicilian-Maltese ar- for many years. This is especially true for Sicily, chipelago were studied, covering a period from the the Egadi Islands, and Malta (Fig. 1). It is the Early Pleistocene to Présent. A full description of merit of Vogel (1988) to have shown that the the methods and the collections used will be given Crocidura species of Sicily has a particular kary- in a fortheoming paper. Data on the Pleistocene otype and represents an endémie species. More re- shrews of Spinagallo, Sicily, were taken from Kot- cently, the same karyotype was found in shrews sakis (1986). of Gozo, which led Vogel et al. (1989) to the con- clusion that ail extant populations of Sicily, Gozo, and the Egadi Islands probably form one biologi- cal species, for which the name Crocidura sicula RESULTS Miller, 1901 is available. However, Vogel et al. (1989) and Sarà et al. (in prep.) found considér- able morphological variation within the species. 1. Characters of extinct and extant populations Fuithermore, extinct populations of Malta and Sicily, described by Malec and Storch (1970), Storch Ail extant populations of C. sicula are charac- (1970) and Kotsakis (1986), could not yet be cor- terized by a sharply bicoloured body and tail. The rectly classified. This paper gives a brief synthesis rostrum of the skull is flat and slender, and the of variation and taxonomy of ail thèse populations, infra-orbital bridge is narrow. The most charac- based on fossil and récent material, and a first idea teristic tooth is P4 : its parastyle is massive and of their possible évolution. angular like a brick, and the dorsal edge of the 214 R. HUTTERER 100 Wm Fig. 1. - Map of Sicily and surrounding archipelagos. The stippled area shows the extension of land to a depth of less than 200 meters below présent sea surface. Fig. 2. - Superimposed outlines of the extemal view of the fourth upper premolar (upper row) and the posterior view of the condylar process of the mandible (below) for samples of Crocidura sicula from (MP) Malta, Pleistocene, (MH) Malta, Holocene, (GR) Gozo, Récent, (SR) Sicily, Récent, and (ER) Egadi Islands, Récent. Scale is 1 mm. cingulum is undulated, not straight (Vogel et al., Egadi, and Gozo. The same applies to the condylar 1989). The same characters are found in fossil process of the mandible. Its shape is rather char- spécimens from Malta (Fig. 2). In principle, the acteristic in shrews (see Hutterer, 1987; Molina form of the parastyle is similar in Pleistocene and and Hutterer, 1989); in Crocidura sicula it is rela- Présent populations, however, the angular form is tively short and stout and différences between the more constant in the extant shrews of Sicily, examined populations only concern the size EVOLUTION OF CROCIDURA SICULA 215 (fig. 2). Other characters checked but not shown ably in their dimensions, Sicily being largest, and here do not indicate any fundamental différence Gozo and Egadi smallest. It is also interesting that between them, either. the size réduction is more pronounced for the tibia length than for the skull size (Fig. 3B)). MB (mm) ^ 2. The problem of the long legs Kotsakis (1986) described remains of Crocidura D Oo from Upper Pleistocene (Wiirmian) sédiments of Spinagallo, Sicily, as a new species, Crocidura esui (corrected here to C. esuae, according to the rules of the ICZN), and he and Esu et al. (1988) also referred fossils from the Ghar-Dalam Cave, Malta, to the new species. Its diagnostic character is a very long tibia, which led the author to the spéculation that the species was adapted to aquatic 7.7 7.9 8,3 8,5 8.7 9 9,1 9,3 9,5 9,7 habits. However, in a review of anatomical adap- UTR (mm) tations of shrews (Hutterer, 1985) it was shown that semi-aquatic species do only occur in the sub- + Gozo R * Malta H □ Malta P Egadi R 0 Sicily R family Soricinae, not in the Crocidurinae. Size (*) B 120 Moreover, a comparison of tibia length and skull Size reauction of Crocidura sicula size (Table I) demonstrates that within the 7 popu- 110 100 Table 1. - Length of tibia (TL) and maxillary breadth 90 (MB) in living and extinct populations of Crocidura sicula (sensu lato). 80 70 Local ity/Period TL + sd n MB ± sd n 60 H MALTA/GOZO SICILY/EGADI 50 Malta, Ghar-Dalam/ Malta EP Malta UP Matta NL Gozo Sicily UP Sicily Egadi Early Pleistocene 16.3 ± 0.6 200 6.6 ± 0.2 51 Localities / Periods Sicily, Spinagallo/ Upper Pleistocene —1— Tibia -*- Mean skull values [Kotsakis 1986] [15.1 17.6] 17 [6.0-6.2] 3 Malta, Ghar-Dalam/ Fig. 3. - A, a scatter diagram of upper toothrow length Upper Pleistocene 14.9 1 - (UTR) versus maxillary breadth (MB) for five popula- sicily/ Récent 13.5 + 0.5 20 6.1 ± 0.2 24 tions of Crocidura sicula. R = Récent, H = Holocene, Malta, Ghar-Dalam/ P = Pleistocene. B, size réduction of C. sicula from the Neolithic 12.5 0.8 5 5.9 ± 0.1 12 Pleistocene to Présent. Mean values for tibia length and for five skull measurements expressed as percentages of Gozo/ Récent 12.3 2 5.8 ± 0.1 27 the Pleistocene population of Ghar-Dalam Cave, Malta. Egadi Is./ Récent 12.3 1 5.7 ± 0.2 8 EP = Early Pleistocene, UP = Upper Pleistocene, NL = Neolithic, other samples from extant populations. lations both variables decreased from the Pleisto- cene to Présent. The longer legs of the Pleistocene shrews were associated with larger body size. As there is no other character which would separate C. esuae from Holocene populations of C. sicula, DISCUSSION I prefer to include it into the latter species. No substantial character différences could be found between Pleistocene shrews of Malta and 3. Size changes from the Pleistocene to Présent Sicily, previously referred to C. esuae, and be- tween Holocene and Récent populations of C. sicula. A comparison of several cranial and skeletal Moreover, it was found that the tibia length varies measurements of the 7 populations shows a re- with body size. Therefore I see no reason to dis- markable variation in size (Fig. 3A). In gênerai, tinguish différent species in this group. However, the Pleistocene samples are the largest, and the a temporal size réduction of 25 % has never been Récent ones the smallest. There is always overlap documented for a shrew and seems quite unusual. between at least two samples. Maximum réduction Fig. 3 also shows that the extremities suffered in size is 25 %. This trend also counts for the tooth more size réduction than the skull, which seems size, for example of M3. A detailed comparison, logical, as there appears to be a limit for the réduc- which will be given in a forthcoming paper, also tion of the brain and dentition. However, it remains shows that the extant populations differ consider- unknown whether a part of the tibia-lengthening 216 R. HUTTERER was due to adaptative processes. An answer to this CONTOLI L., B. BENINCASA-STAGNI & A.R. question would require a detailed knowledge of the MARENZI, 1989. Morfometria e morfologia di landscape of Malta and Sicily during the Pleistocene.