@article {24, title = {Characterization of the North American beaver (Castor canadensis) papillomavirus genome.}, journal = {Vet Microbiol}, volume = {168}, year = {2014}, month = {2014 Jan 10}, pages = {214-20}, abstract = {

The papillomaviruses comprise a large group of viruses that cause proliferations of the stratified squamous epithelium of skin and mucosa in a variety of animals. An earlier report identified a novel papillomavirus of the North American beaver, Castor canadensis (CcanPV1) that was associated with cutaneous exophytic lesions. In the current study, we determined the sequence of the complete 7435 basepair genome of CcanPV1. The genome contains an Upstream Regulatory Region located between the end of L1 and the start of E6, and seven canonical papillomavirus open reading frames encoding five early (E6, E7, E1, E2, and E4) and two late (L2 and L1) proteins. No E5 open reading frame was detected. Phylogenetic analysis of the CcanPV1 genome places the virus between the genera Kappapapillomavirus and Mupapillomavirus. Analyses of the papillomavirus genomes detected in different species of the order Rodentia indicate these viruses do not form a monophyletic clade.

}, keywords = {Animals, Genome, Viral, Molecular Sequence Data, Open Reading Frames, Papillomaviridae, Papillomavirus Infections, Phylogeny, Rodentia, United States}, issn = {1873-2542}, doi = {10.1016/j.vetmic.2013.11.011}, author = {Rogovskyy, Artem S and Chen, Zigui and Burk, Robert D and Bankhead, Troy} } @article {23, title = {Mitochondrial genomes reveal slow rates of molecular evolution and the timing of speciation in beavers (Castor), one of the largest rodent species.}, journal = {PLoS One}, volume = {6}, year = {2011}, month = {2011 Jan 28}, pages = {e14622}, abstract = {

BACKGROUND: Beavers are one of the largest and ecologically most distinct rodent species. Little is known about their evolution and even their closest phylogenetic relatives have not yet been identified with certainty. Similarly, little is known about the timing of divergence events within the genus Castor.

METHODOLOGY/PRINCIPAL FINDINGS: We sequenced complete mitochondrial genomes from both extant beaver species and used these sequences to place beavers in the phylogenetic tree of rodents and date their divergence from other rodents as well as the divergence events within the genus Castor. Our analyses support the phylogenetic position of beavers as a sister lineage to the scaly tailed squirrel Anomalurus within the mouse related clade. Molecular dating places the divergence time of the lineages leading to beavers and Anomalurus as early as around 54 million years ago (mya). The living beaver species, Castor canadensis from North America and Castor fiber from Eurasia, although similar in appearance, appear to have diverged from a common ancestor more than seven mya. This result is consistent with the hypothesis that a migration of Castor from Eurasia to North America as early as 7.5 mya could have initiated their speciation. We date the common ancestor of the extant Eurasian beaver relict populations to around 210,000 years ago, much earlier than previously thought. Finally, the substitution rate of Castor mitochondrial DNA is considerably lower than that of other rodents. We found evidence that this is correlated with the longer life span of beavers compared to other rodents.

CONCLUSIONS/SIGNIFICANCE: A phylogenetic analysis of mitochondrial genome sequences suggests a sister-group relationship between Castor and Anomalurus, and allows molecular dating of species divergence in congruence with paleontological data. The implementation of a relaxed molecular clock enabled us to estimate mitochondrial substitution rates and to evaluate the effect of life history traits on it.

}, keywords = {Animals, Evolution, Molecular, Genetic Speciation, Genome, Mitochondrial, Kinetics, Phylogeny, Rodentia}, issn = {1932-6203}, doi = {10.1371/journal.pone.0014622}, author = {Horn, Susanne and Durka, Walter and Wolf, Ronny and Ermala, Aslak and Stubbe, Annegret and Stubbe, Michael and Hofreiter, Michael} } @article {25, title = {Re-evaluation of Sinocastor (Rodentia: Castoridae) with implications on the origin of modern beavers.}, journal = {PLoS One}, volume = {5}, year = {2010}, month = {2010 Nov 15}, pages = {e13990}, abstract = {

The extant beaver, Castor, has played an important role shaping landscapes and ecosystems in Eurasia and North America, yet the origins and early evolution of this lineage remain poorly understood. Here we use a geometric morphometric approach to help re-evaluate the phylogenetic affinities of a fossil skull from the Late Miocene of China. This specimen was originally considered Sinocastor, and later transferred to Castor. The aim of this study was to determine whether this form is an early member of Castor, or if it represents a lineage outside of Castor. The specimen was compared to 38 specimens of modern Castor (both C. canadensis and C. fiber) as well as fossil specimens of C. fiber (Pleistocene), C. californicus (Pliocene) and the early castorids Steneofiber eseri (early Miocene). The results show that the specimen falls outside the Castor morphospace and that compared to Castor, Sinocastor possesses a: 1) narrower post-orbital constriction, 2) anteroposteriorly shortened basioccipital depression, 3) shortened incisive foramen, 4) more posteriorly located palatine foramen, 5) longer rostrum, and 6) longer braincase. Also the specimen shows a much shallower basiocciptal depression than what is seen in living Castor, as well as prominently rooted molars. We conclude that Sinocastor is a valid genus. Given the prevalence of apparently primitive traits, Sinocastor might be a near relative of the lineage that gave rise to Castor, implying a possible Asiatic origin for Castor.

}, keywords = {Animals, China, Female, Fossils, Geography, Male, North America, Phylogeny, Rodentia, Skull, Species Specificity}, issn = {1932-6203}, doi = {10.1371/journal.pone.0013990}, author = {Rybczynski, Natalia and Ross, Elizabeth M and Samuels, Joshua X and Korth, William W} } @article {26, title = {Development of nine new microsatellite loci for the American beaver, Castor canadensis (Rodentia: Castoridae), and cross-species amplification in the European beaver, Castor fiber.}, journal = {Mol Ecol Resour}, volume = {9}, year = {2009}, month = {2009 Mar}, pages = {551-4}, abstract = {

We developed nine new nuclear dinucleotide microsatellite loci for Castor canadensis. All loci were polymorphic, except for one. The number of alleles ranged from two to four and from five to 12 in populations from Arizona and Wisconsin, respectively. Average heterozygosity ranged from 0.13 to 0.86 per locus. Since cross-species amplification in Castor fiber was successful only in four loci, we tested also nine recently published C. canadensis loci in the Eurasian species. Eight of the published loci amplified; however, three were monomorphic. The number of alleles was lower in C. fiber than in C. canadensis at all loci tested.

}, issn = {1755-098X}, doi = {10.1111/j.1755-0998.2008.02364.x}, author = {Pelz-Serrano, Karla and Munguia-Vega, Adrian and Piaggio, Antoinette J and Neubaum, Melissa and Munclinger, Pavel and P{\'a}rtl, Adam and VAN Riper Iii, Charles and Culver, Melanie} } @article {27, title = {Isolation and characterization of microsatellite loci in the beaver (Castor canadensis).}, journal = {Mol Ecol Resour}, volume = {8}, year = {2008}, month = {2008 May}, pages = {616-8}, abstract = {

We have isolated and characterized 10 microsatellite loci in the beaver (Castor canadensis). Sixty individuals from southern and central Illinois were screened at each locus. All loci exhibited moderate levels of polymorphism, ranging from five to 13 alleles per locus with average heterozygosity ranging from 0.317 to 0.867. Locus Cca5 deviated significantly from HWE (P~<~0.001). The locus pair Cca4/Cca5 was shown to be in linkage disequilibrium in southern Illinois, but not in the central Illinois population. The remaining eight loci will be useful in investigations of mating and kinship patterns in beaver populations in Illinois.

}, issn = {1755-098X}, doi = {10.1111/j.1471-8286.2007.02016.x}, author = {Crawford, J and Liu, Z and Nelson, T and Nielsen, C and Bloomquist, C} } @article {28, title = {Comparative morphological study on the stereo-structure of the lingual papillae and their connective tissue cores of the American beaver (Castor canadensis).}, journal = {Okajimas Folia Anat Jpn}, volume = {82}, year = {2006}, month = {2006 Feb}, pages = {127-37}, abstract = {

The lingual papillae and the connective tissue cores (CTC) of the American beaver were examined by light and scanning electron microscopy. The tongue of American beaver was about 9 cm in length, 3.5 cm in width, and has a lingual prominence. Four types of papillae (filiform, fungiform, vallate and foliate papillae) were observed. The filiform papillae can be classified into three types (filiform, large filiform and dorm-like papillae). Filiform papillae distributed on the anterior tongue and posterior of the lingual prominence consisted of a posterior thick main process and several small accessory processes. After removal of the epithelium, the CTCs of the filiform papillae had U-shaped, horseshoe-like primary cores with 10-15 rod-shaped small accessory cores. Large filiform papillae were distributed at the anterior margin of the lingual prominence. Dome-like papillae were distributed at the top of lingual prominence. Fungiform papillae were observed two types. Fungiform papillae, which were distributed at the anterior tongue, were round shaped. Fungiform papillae of the posterior of the lingual prominence were large and surrounded with a papillary groove. At the posterior of the tongue, three vallate papillae were arranged in a triangular pattern. Foliate papillae were on 22 to 25 parallel ridges and grooves.

}, keywords = {Animals, Connective Tissue, Epithelium, Feeding Behavior, Female, Male, Microscopy, Microscopy, Electron, Scanning, Rodentia, Tongue}, issn = {0030-154X}, doi = {10.2535/ofaj.82.127}, author = {Shindo, Junji and Yoshimura, Ken and Kobayashi, Kan} } @article {29, title = {The chromosomes of the Canadian Beaver Castor canadensis.}, journal = {Can J Genet Cytol}, volume = {21}, year = {1979}, month = {1979 Mar}, pages = {37-42}, abstract = {

A chromosome analysis of 24 Canadian beavers, Castor canadensis Kuhl (12 males and 12 females), captured in Laurentides Park, Q{\'e}bec, has been performed from preparations of blood lymphocyte and skin cultures. The chromosome number was found to be 2n = 40. Measurements were made to determine relative lengths and arm ratios of chromosomes, which are metacentric or submetacentric. Results are in agreement with those already published regarding the chromosome number, but differ in the identification of the X chromosome, and in the morphology of the Y and some autosomes. C- ad G-banding techniques allowed the precise identification of individual chromosome pairs. A detailed idiogram of G-bands is presented.

}, keywords = {Animals, Chromosome Banding, Chromosomes, Female, Karyotyping, Male, Rodentia, Sex Chromosomes}, issn = {0008-4093}, doi = {10.1139/g79-006}, author = {Genest, F B and Morisset, P and Patenaude, R P} }