| Iberian shrew | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Eulipotyphla |
| Family: | Soricidae |
| Genus: | Sorex |
| Species: | S. granarius |
| Binomial name | |
| Sorex granarius Miller, 1910 | |
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| Iberian shrew range[image reference needed] | |
TheIberian shrew orLagranja shrew (Sorex granarius) is a species ofmammal in the familySoricidae. It is found inPortugal andSpain.
Relative to otherSorex species,S. granarius is intermediate in size, with a total body length (including the tail) of approximately 103.6 mm and an average weight of 6.3 g.[2] Adults are identified by their dark-colored back, which contrasts with their lighter tan sides and off-white belly.[2] The fur of young shrews has only two discernible colors: the darker color on the back and the lighter color on the belly.[2] In both adults and juveniles, the fur is also adapted for cold, damp habitats: each guard hair possesses an indentation along its length that helps to prevent water from reaching the body.[2]
The skull ofS. granarius can be used to distinguish it from other species belonging to the EuropeanSorex araneus group of shrews.[2] Comparatively, the snout ofS. granarius is small and flat, themandible possesses a diminishedcoronoid process and a narrow angular process, and thetemporal fossa of the skull resembles a triangle.[2]
TheSorex araneus group of European shrews consists ofS. araneus,S. coronatus, andS. granarius, with all members belonging to the orderSoricomorpha and the family Soricidae.[2] Because their morphology is virtually identical, species definitions rely primarily on genetic differences.[3][4] The phylogenetic positioning ofS. granarius has been historically difficult even with the use of genetic analyses. Mitochondrial DNA suggests that it is more closely related toS. araneus, while Y-chromosome markers imply a closer relationship withS. coronatus.[3] More recent studies using both autosomal and X-chromosomal markers offer greater support for the phylogenetic grouping ofS. granarius withS. coronatus,[5] as opposed to the traditional grouping ofS. granarius andS. araneus.[2]
The distribution ofS. granarius is lateral through theCentral System mountain range of the Iberian Peninsula and reaches Galicia, Spain in the north and the Tagus (Tejo) River in the south.[2] There is also speculation ofS. granarius cohabitation withS. coronatus in theIberian System.[4] In the wild,S. granarius is known to live in woody areas consisting of juniper (Juniperus nana),[4] beech (Fagus sylvatica), Pyrenean oak (Quercus pyrenaica), Scots pine (Pinus sylvestris), evergreen oak (Quercus rotundifolia), ash (Fraxinus), or birch (Betula) at 500 to 2000 meter elevations.[2]
Domestic cats (Felis catus), European wild cats (Felis silvestris), and barn owls (Tyto alba) have been noted to prey uponS. granarius[2].
In the group ofSorex araneus shrews, males possess distinctive XY1Y2 sex chromosomes.[2][3][6] The Y chromosome comprises two portions: the original Y sex chromosome (Y1) and a portion that forms an arm of one of the autosomal chromosomes (Y2).[6]S. granarius is unique among this group because it possesses primarilyacrocentric chromosomes with only two pairs ofmetacentric chromosomes, whereasS. araneus has a complete set of metacentric chromosomes.[6]
The telomere length and location ofS. granarius further distinguish the organism fromS. araneus:S. araneus possesses small telomeres on each chromosome that range in size from 6.8 to 15.2 kb.[7] The telomeres ofS. granarius are located only on the short arms of the acrocentric chromosomes, and can reach lengths of approximately 300 kb, making them the largest mammalian telomeres described to date.[5] Thesemega-telomeres appear to preserve their impressive length through both the enzyme telomerase and active homologous recombination.[7] Additionally, the intermittent repetitive sequences ofS. granarius telomeres are infused with ribosomal DNA, and it is the only knownEutherian mammal with this feature.[7]
