Title: STRUCTURE, BIODIVERSITY & HISTORICAL BIOGEOGRAPHY OF NEMATODE FAUNAS IN HOLARCTIC RUMINANTS: MORPHOLOGICAL & MOLECULAR DIAGNOSES FOR T. BOREOARCTICUS SP N. (NEMATODA: OSTERTAGIINAE), A DIMORPHIC CRYPTIC SPECIES IN MUSKOXEN...
Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 18, 1999
Publication Date: N/A
Interpretive Summary: Biodiversity of the nematode faunas in North American ruminants continues to be poorly defined. Discovery of a new species of a medium stomach worm, Teladorsagia boreoarcticus, in arctic ruminants highlights this situation and reenforces the concept that the fauna in North America is composed of endemic versus recently introduced species, both of which may have an impact on animal health. Teladorsagia boreoarcticus appears to represent a component of a complex of cryptic, or poorly differentiated, species in bovids and cervids from North America and the Holarctic region. Discovery and description of this species, based on molecular and morphological characters, serves to indicate our incomplete knowledge of the nematodes that may be exchanged between domestic and wild sheep. Our lack of understanding of the ecological limitations on dissemination of these nematodes is emphasized. Significantly, this indicates that there are more species of medium stomach worms that parasitize ruminants than previously recognized, although this fauna was thought to be well defined. Elucidation of the historical and geographical influences on diversity and distribution of nematodes in domestic and wild ruminants is requisite to define the interface between agricultural and natural ecosystems, and the potential for emergence of pathogens.
Discovery of the ostertagiine nematode, Teladorsagia boreoarcticus sp. n., in muskoxen, Ovibos moschatus, from the central Canadian Arctic highlights the paucity of knowledge about the genealogical and numerical diversity of nematode faunas characteristic of artiodactyls at high latitudes across the Holarctic. Teladorsagia boreoarcticus is a dimorphic cryptic species distinguished from T. circumcincta/T. trifurcata in domestic sheep by a 13% divergence in the ND4 region of mt DNA, constant differences in the synlophe and significantly longer esophageal valve, spicules, gubernaculum and bursa. Teladorsagia boreoarcticus represents an archaic component of the North American fauna and may have a Holarctic distribution in muskoxen and caribou. Recognition of T. boreoarcticus in muskoxen, in part corroborates hypotheses for the existence of a cryptic species complex of Teladorsagia spp. among Caprinae and Cervidae at high latitudes and indicates the importance of climatological determinants during the late Tertiary and Pleistocene on diversification of the fauna. Also reinforced is the concept of the North American fauna as a mosaic of endemic and introduced species. Discovery of this species has additional implications and indicates: (1) our knowledge is incomplete relative to potentially pathogenic nematodes that could be exchanged among domestic and wild caprines; (2) we do not have sufficient knowledge of the fauna to understand the interface between agricultural and natural ecosystems across the Holarctic.