Acta Theriol (2014) 59:407–413 DOI 10.1007/s13364-014-0176-y
ORIGINAL PAPER
Morphometric and pelage color variation of two sibling species of shrew (Mammalia: Soricomorpha) Shunde Chen & Yang Liu & Zhiyu Sun & Feiyun Tu & Changkun Fu & Qiong Wang & Shaoying Liu
Received: 3 November 2013 / Accepted: 18 February 2014 / Published online: 5 March 2014 # Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland 2014
Abstract Pelage color variants have been documented in some small mammals, but there is not any reported about coat color variation in shrews. Here, pelage color variants of the two sibling species (Sorex cylindricauda and Sorex bedfordiae) were uncovered in different sampling sites. Our data may initiate new interest to pelage color variants in small mammals. Furthermore, the classification of two striped shrews has been controversial for several decades. We conducted a detailed examination of the morphometric characters for the two sibling shrews. Significant differences between the Communicated by: Jan M. Wójcik Electronic supplementary material The online version of this article (doi:10.1007/s13364-014-0176-y) contains supplementary material, which is available to authorized users. S. Chen : C. Fu : Q. Wang College of Life Sciences, Sichuan Normal University, Chengdu 610066, People’s Republic of China S. Chen e-mail:
[email protected] C. Fu e-mail:
[email protected] Q. Wang e-mail:
[email protected] Y. Liu : Z. Sun : S. Liu (*) Sichuan Academy of Forestry, Chengdu 610081, People’s Republic of China e-mail:
[email protected] Y. Liu e-mail:
[email protected] Z. Sun e-mail:
[email protected] F. Tu Institute of Wildlife Conservation, Jiangxi Academy of Forestry, Nanchang 330013, People’s Republic of China e-mail:
[email protected]
two species morphologically confirmed the two-species classification status. Keywords Sorex cylindricauda . Sorex bedfordiae . Pelage color variation . Morphometric analysis . Soricidae
Introduction The Sorex genus is type genus of Soricidae and consists of 77 species (Hutterer 2005). Eighteen species of them have been reported to occur in China, and most of them lack a comprehensive morphological study due to limited available samples (Hoffmann 1987; Lunde et al. 2004). Stripebacked shrews Sorex cylindricauda (Milne-Edwards 1871) and lesser striped shrew Sorex bedfordiae (Thomas 1911) are two sibling species, which are distinguished from other shrews by a dorsal stripe along the dorsal spine. The classification of two striped shrews has been controversial for several decades. They had been treated as three valid species (Milne-Edwards 1871; Thomas 1911), a single species (Allen 1938; Ellerman and Morrison-Scott 1966), or two valid species (Corbet 1978; Hoffmann 1987; Wu et al. 1991; Wang 2003; Hutterer 2005) in different taxonomic revisions. However, neither a comprehensive morphometric statistical analysis nor a detailed comparison of the two species is available in literature. Coat color is an important phenotypic characteristic in small mammals (Lai et al. 2008). Although many coat color variants due to melanin synthesis and distribution have been documented in small mammals (Smith et al. 1972; Silvers 1979; Steiner et al. 2009), there is not any reported about coat color variation in shrews. Furthermore, it has already been reported that coat color variants have led to systematic confusion in pikas and hares (Ge et al. 2012).
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Acta Theriol (2014) 59:407–413
Material and methods Specimens and data collection A total of 355 pelage specimens of S. bedfordiae from 28 locations and 46 individuals of S. cylindricauda from 12 locations were examined in this study (Table S1 and Fig. S1). All specimens studied were adult individuals. The coloration of each specimen’s skins was compared by using photographs. Photographs were taken with a Canon EOS7D and saved in TIFF format.
Morphometric analysis
Fig. 1 Representative pelage color variation in museum collections in S. cylindricauda. A group was collected from Tianquan and Meigu; B group was collected from Baoxing
In addition, biological data for the two striped shrews are absent, and they are listed as “Data Deficient” by the International Union for Conservation of Nature and Natural Resources (IUCN) (Smith and Johnston 2011a, b). Thus, the purposes of this study are to provide a comprehensive morphometric study and to evaluate the phenomenon of pelage color variants of two striped shrews.
A total of 101 intact skulls of adult specimens were further examined in the morphometric study, including 68 S. bedfordiae and 33 S. cylindricauda skulls (Table S1; Table S2). All pelage and skull specimens were deposited in Sichuan Academy of Forestry (Chengdu, China). External and cranial measurements were made using vernier calipers to the nearest 0.01 mm. Eleven external and cranial characters were recorded for each specimen. Two external measurements were recorded from specimen tags, including head–body length and length of tail. Nine cranial measurements followed those given by Hoffmann (1987) and Yang et al. (2007). The cranial measurements included (1) condylo-incisor length (CIL), occipital condyles to anterior tips of first incisor; (2) cranial breadth (CB), greatest breadth of braincase; (3) maxillary breadth (MB), greatest distance between tips of maxillary processes; (4) M2 to M2 breadth (M2–M2), greatest distance between anterior labial margins of
Fig. 2 Representative pelage color variation in museum collections in S. bedfordiae. A group was collected from Meigu and Jiuzhaigou; B group was collected from Baoxing; C group was collected from Yajiang and Hailuogou
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Table 1 Univariate statistics for selected external and cranial measurements of adult S. cylindricauda and S. bedfordiae Measurements
S. cylindricauda (N=33)
S. bedfordiae (N=68)
Minimum
Maximum
Mean
Standard deviation
Coefficient of variation
Minimum
Maximum
Mean
Standard deviation
Coefficient of variation
Head–body length
52
84
69.73
7.35
54.14
47
76
59.10
6.50
42.32
Length of tail Condyle–incisor length Cranial breadth Maxillary breadth M2–M2 breadth Interorbital breadth Palate–incisor length Lower tooth row length Upper tooth row length Mandibular length
45 18.54 8.12 4.50 4.30 3.34 7.72 7.10 7.50 11.00
67 21.72 9.50 5.70 5.90 4.32 9.60 8.20 9.20 13.20
55.83 19.73 8.98 5.13 4.85 3.72 8.50 7.71 8.32 11.87
5.08 0.75 0.32 0.29 0.37 0.22 0.48 0.26 0.44 0.58
25.88 0.57 0.10 0.08 0.14 0.05 0.23 0.07 0.20 0.34
47 17.10 7.10 3.30 3.12 3.00 7.10 5.68 7.00 10.0
62 18.90 8.80 5.30 5.00 3.90 8.50 7.60 8.30 10.96
55.94 17.94 8.12 4.38 4.03 3.40 7.54 6.89 7.37 10.48
3.57 0.40 0.37 0.33 0.27 0.17 0.25 0.25 0.25 0.25
12.79 0.16 0.14 0.11 0.07 0.02 0.06 0.06 0.06 0.06
second upper molars; (5) interorbital breadth (IOB), least lateral diameter of skull at anterior ends of orbits, just posterior to maxillary processes; (6) palate–incisor length (PIL), posterior margin of palate in midline to anterior tips of first incisors; (7) upper tooth row length (UTRL), greatest length of tooth row from posterior margin of alveolus of M3 to anterior tip of the first incisor; (8) lower tooth row length (LTRL), greatest length of lower tooth row at alveolus of M3 to anterior tip of incisors; and (9) mandibular length (ML), length of mandible including the first incisor. All statistical analyses were done using the Statistical Package for the Social Sciences (SPSS version 16.0). All variables were transformed into logarithms to eliminate the bias effect of large measurements in multivariate analysis Table 2 Independent-sample t test of different variables between the two striped shrews Variables
Sorex cylindricauda
Sorex bedfordiae
t
p
t
p
Head–body length Length of tail Condylo-incisor length Cranial breadth Maxillary breadth M2–M2 breadth Interorbital breadth Palate–incisor length Lower tooth row length Upper tooth row length
7.377 −0.123 15.562 11.249 10.970 12.515 7.787 13.087 13.641 13.503
0.000** 0.902 0.000** 0.000** 0.000** 0.000** 0.000** 0.000** 0.000** 0.000**
7.067 −0.109 12.777 11.884 11.499 11.215 7.093 10.700 12.227 11.222
0.000** 0.913 0.000** 0.000** 0.000** 0.000** 0.000** 0.000** 0.000** 0.000**
Mandibular length
16.594
0.000**
12.977
0.000**
**
p
