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PubMed1985

Basal metabolic rates in mammals: taxonomic differences in the allometry of BMR and body mass.

No single equation adequately describes the allometric relation between body mass and BMR for mammals. Least squares regression of log-transformed data for 248 eutherian species results in a line with a slope (-0.30) significantly different from that of Kleiber's line (-0.25). Interordinal comparisons of least squares regressions of log-transformed BMR and mass suggest that the Insectivora have a significantly steeper slope to their allometric relationship than do most other orders, while the non-insectivore orders are statistically homogeneous with respect to slope. With respect to elevation, Edentata have the lowest BMRs; Marsupialia, Primates and Chiroptera are indistinguishable from each other but above the edentates; Primates, Chiroptera, Rodentia, Lagomorpha and Carnivora form the next highest homogeneous grouping; and Artiodactyla have the highest BMRs, significantly greater than all but Lagomorpha and Carnivora. Analysis of intraordinal variation within the Rodentia suggests significant heterogeneity among families in BMR-mass allometry.

Animals↗
PubMed1990

Ultrastructure of synapses and golgi analysis of neurons in neocortex of the lateral gyrus (visual cortex) of the dolphin and pilot whale.

Qualitative and computerized quantitative analyses of ultrastructural features of synapses in different layers of the primary visual cortex in the dolphin (Stenella coeruleoalba) and the pilot whale (Globicephala melaena) were carried out. Also, Golgi and cytoarchitectonic analyses were performed in the same species of cetaceans and, additionally, in Tursiops truncatus and Phocaena phocaena. It was found that on a synaptic level, as well as in cytoarchitectonic and Golgi features, the neocortex of cetaceans combines evolutionary progressive features and conservative features with a marked prevalence of the latter. Thus, the total number of synapses in visual neocortex in cetaceans is closer to this value in higher Primates. On the other hand, the laminar density of synapses per mm3 is generally the same in all layers in cetacean visual cortex and numerically is close to values found in small lissencephalic brains. Also, the synapse/neuron ratio in the dolphin visual cortex is of the same order as in cortices of rodents and lagomorphs and much higher than in cortices of advanced terrestrial mammals. Layers I and II contain approximately 70% of the total synapses in the cortical slab through visual cortex. Layer I also contains the extraverted dendrites of neurons of layer II and thus these two layers resemble a paleoarchicortical type of organization superimposed on a more typical neocortical organization of the lower cortical layers. In this respect the convexity neocortex of cetaceans is generally similar to the neocortices of phylogenetically ancient extant mammals such as basal Insectivora and Chiroptera.

Animals↗
PubMed1988

Tension fibroblasts and the connective tissue matrix of the spiral ligament.

Fibroblasts with stress fibers (tension fibroblasts) have previously been described in the marginal region of the spiral ligament of bats and mice (Henson et al., 1984, 1985). The location, structure and attachments of these cells and the fact that they contain contraction associated proteins, have suggested a role in the generation of tension within the basilar membrane-spiral ligament complex. In this study the structure of these fibroblasts and their relationships to different types of connective tissue matrices were examined in representative Marsupalia, Insectivora, Chiroptera, Rodentia, Lagomorpha, Carnivora and Primates. Tension fibroblasts occur in all species but they are remarkably different in their actin filament content, their structure and distribution, and in their association with the extracellular matrix and otic capsule. Six types of matrices are described (dense filamentous, bundled, laminated, honeycombed, trabeculated and loose filamentous). The configurations of the cells and fibers indicate that tension on the basilar membrane may be accomplished in different ways and to different degrees in different mammals. The arrangement of the matrix and cells in some animals is markedly different in the parts of the cochlea that respond to high, middle and low frequencies.

Actins↗
PubMed2004

Apparent scarcity of glial fibrillary acidic protein expression in the brain of the pygmy shrew Sorex minutus as revealed by immunocytochemistry.

We examined astroglial cells in the brain of the pygmy shrew Sorex minutus (Insectivora). For that purpose we labeled glial fibrillary acidic protein (GFAP) immunohistochemically in brain sections with a polyclonal antibody. Antigen retrieval experiments were performed to counteract formaldehyde fixation masking of GFAP epitopes. Our results showed remarkable paucity of GFAP-immunoreactive cells and fibers in the cerebral cortex and nuclei, as well as in the majority of the diencephalic and mesencephalic structures. In the forebrain, significant numbers of GFAP-containing astrocytes were found only in the ependyma and subventricular zones, superficial part of layer I of the cerebral cortex, and the majority of white matter structures. In the diencephalon, habenular nuclei were rich in GFAP-immunopositive astrocytes and labeled radial fibers were extended between median eminence and the third ventricle. A considerably higher density of labeled astrocytes was detected in the caudal brainstem and cerebellum. In contrast, in the mouse brain, immunoreactive astrocytes were present in large quantities in various structures. Staining of sections of the shrew brain against glutamine synthetase revealed abundance of immunofluorescent astrocytes in many areas, especially in the shrew cerebral cortex. It seems probable that in the shrew brain only a limited fraction of astroglia expresses GFAP, while other astroglial cells can be detected with different markers. It is possible that the rodent type of astroglial GFAP expression might not be common to insectivores and probably to some other mammalian orders.

Animals↗
PubMed2005

The broad spectrum of Trichinella hosts: from cold- to warm-blooded animals.

In recent years, studies on Trichinella have shown that the host range is wider than previously believed and new Trichinella species and genotypes have been described. Three classes of vertebrates are known to act as hosts, mammals, birds and reptiles, and infected vertebrates have been detected on all continents but Antarctica. Mammals represent the most important hosts and all Trichinella species are able to develop in this vertebrate class. Natural infections with Trichinella have been described in more than 150 mammalian species belonging to 12 orders (i.e., Marsupialia, Insectivora, Edentata, Chiroptera, Lagomorpha, Rodentia, Cetacea, Carnivora, Perissodactyla, Artiodactyla, Tylopoda and Primates). The epidemiology of the infection greatly varies by species relative to characteristics, such as diet, life span, distribution, behaviour, and relationships with humans. The non-encapsulated species Trichinella pseudospiralis, detected in both mammals (14 species) and birds (13 species), shows a cosmopolitan distribution with three distinguishable populations in the Palearctic, Nearctic and Australian regions. Two additional non-encapsulated species, Trichinella papuae, detected in wild pigs and saltwater crocodiles of Papua New Guinea, and Trichinella zimbabwensis, detected in farmed Nile crocodiles of Zimbabwe, can complete their life cycle in both mammals and reptiles. To the best of our knowledge, T. papuae and T. zimbabwensis are the only two parasites known to complete their entire life cycle independently of whether the host is warm-blooded or cold-blooded. This suggests that these two Trichinella species are capable of activating different physiological mechanisms, according to the specific vertebrate class hosting them.

Animals↗
PubMed1998

A new spontaneous animal model of NIDDM without obesity in the musk shrew.

The EDS (early-onset diabetes in suncus) colony has been developed as a new closed breeding colony of the musk shrew (Suncus murinus, Insectivora) exhibiting a high incidence of spontaneous diabetes mellitus. We investigated the characteristic features of diabetic shrews in this colony. All diabetic shrews are characterized by glycosuria (Tes-tape value > or = 3+), hyperglycemia (23.3 +/- 0.8 mmol/l) and polyuria, and they were affected by the age of 3 months. Cumulative incidence (64.1% in males and 27.8% in females) was kept intact after the age of 3 months. The growth pattern of diabetic shrews was similar to that of non-diabetic shrews, and obesity was not consistent in diabetic shrews. The intraperioneal glucose tolerance test revealed both impaired glucose tolerance and impaired insulin secretion in diabetic shrews. Insulin sensitivity of diabetic shrews decreased in the intraperioneal insulin tolerance test. Neither severe hypertrophy nor lymphocytic infiltration was observed in pancreatic islets of diabetic shrews. These facts suggested that diabetic shrews in the EDS colony should be classified as early-onset non-insulin dependent diabetes mellitus (NIDDM) without obesity. Early-onset of severe hyperglycemia with impaired glucose tolerance is a distinctive character compared with other non-obese NIDDM models in rodents. We concluded that the diabetic shrews in the EDS colony are a new animal model of human NIDDM without obesity.

Age of Onset↗
PubMed1998

Toxin-induced IDDM (insulin dependent diabetes mellitus) in the musk shrew.

We administered streptozotocin (STZ) and alloxan (AL) to the musk shrew (Suncus murinus, Insectivora) to determine the effective diabetogenic dose of the two toxins for this species. A single intraperitoneal (i.p.) injection of 75 mg/kgBW or the consecutive 5-day s injection of 25 mg/kgBW of STZ to non-fasted shrews, effectively (100%) induced hyperglycemia (> or = 300 mg/dl) with hypoinsulinaemia (< 30% of control level) in male shrews at 10 days after administration. Morphological studies showed cytological changes of B cells in the pancreatic islets of diabetic shrews. Hyperglycemic shrews induced by STZ were thus in IDDM (insulin dependent diabetes mellitus), and showed high susceptibility to the diabetogenic effect of STZ as compared with rodents. Shrews showed a sex difference in the diabetogenic susceptibility to STZ as do mice (male > female). They also showed a species specific resistance to the diabetogenic effect of AL. Of the eight shrews (with 8-hr fasting) that has been treated with a single injection of 200 mg/kgBW of AL, seven (88%) survived at least 10 days, showing no signs of hyperglycemia. All shrews died within 3 day s after injection of 250 or 300 mg/kgBW. These results indicated that the STZ-induced diabetic shrew is a unique animal model and may be useful for IDDM research. On the other hand, the musk shrew was highly resistant to the diabetogenic effects of AL.

Alloxan↗
PubMed2000

Fatty liver and hyperlipidemia in IDDM (insulin-dependent diabetes mellitus) of streptozotocin-treated shrews.

Severe IDDM (insulin-dependent diabetes mellitus) was produced in the musk shrew (Suncus murimus, Insectivora) by a high dose (a single intraperitoneal injection of 100 mg/kg Body Weight) of streptozotocin (STZ) injection. All shrews that were administered a high dose of STZ exhibited hyperglycemia (449 +/- 16 mg/dl vs 73 +/- 4 mg/dl in controls) and hypoinsulinemia(0.25 +/- 0.07 ng/ml vs 10.96 +/- 1.97 ng/ml in controls) with ketosuria 10 days after injection. Their livers were enlarged and exhibited ayellowish-brown color with marked triglyceride (TG) accumulation (63.25 +/- 7.10 mg/g Liver vs 2.11 +/- 0.19 mg/g Liver in controls). It is probable that the increased influx of fatty acids into the liver induced by hypoinsulinemia and the low capacity of excretion of lipoprotein secretion from liver in the musk shrew resulting from a deficiency of apolipoprotein B synthesis play important roles in fatty liver formation. Hyperlipidemia was another feature in shrews with severe IDDM. The blood TG level was especially high in these shrews (899 +/- 178 mg/dl vs 23 +/- 5 mg/dl in controls). These results indicate that the IDDM shrew, induced by high doses of STZ, is a unique model characterized by fatty liver and hyperlipidemia and may be useful for studying lipid metabolism of IDDM.

Animals↗
PubMed2000

Tissue, sex and age specific accumulation of heavy metals (Zn, Cu, Pb, Cd) by populations of the mole (Talpa europaea L.) in a central urban area.

Heavy metal accumulation was studied in urban populations of moles, Talpa europaea L. (Insectivora) at three sites along the "Donaukanal" in Vienna. Kidneys, liver, lung, gonads, spleen, pancreas, femur, stomach + content, heart and skin were analysed for Zn, Cu, Pb and Cd contents. Female moles showed higher Zn concentrations in spleen, gonads and skin, higher Cd concentrations in femur and stomach and lower Cu content in kidneys compared to males. Age classes were determined using teeth section. A significant increase in Cd concentration with age was found in kidneys, liver, heart, lung, skin and femur, with the highest increase for kidney samples. Pb accumulated in bone tissue (femur) with increasing age. Although significant site differences in heavy metal concentrations of soil and vegetation samples existed, these differences were only partly reflected by tissue contents.

Aging↗
PubMed1998

Neuromuscular transmission and innervation in the urinary bladder of the insectivore Suncus murinus.

In isolated preparations of the urinary bladder detrusor of the house musk shrew Suncus murinus (order: insectivora; family: Soricidae), electrical field stimulation (0.5-32 pulses/s) evoked neurogenic contractile responses that were markedly attenuated by atropine (1 microM). The non-cholinergic component was reduced but not abolished by the P2-purinoceptor antagonist, suramin (300 microM). Thus, neuromuscular transmission in the suncus urinary bladder is effected by cholinergic and purinergic nerves together with an as-yet unidentified component. Using immunohistochemical methods, the suncus urinary bladder was seen to be supplied by nerves containing neuropeptide Y, tyrosine hydroxylase, vasoactive intestinal polypeptide, galanin, substance P, calcitonin gene-related peptide and type I nitric oxide synthase. The pattern of responses to electrical field stimulation was more similar to that of humans and Old World primates, than to that of rodents or lagomorphs. The pattern of innervation of the bladder wall, in terms of the distribution of populations containing a given neuropeptide, was very similar to that in humans. Hence, Suncus murinus may provide a novel species for modelling the neuropharmacology of the human bladder, and also for studying the evolution of autonomic innervation.

Animals↗
PubMed2001

Calbindin-D28k and calretinin immunoreactive neurons in the olfactory bulb of the musk shrew, Suncus murinus.

The distribution, morphological features, and postnatal development of calbindin-D28k (CB) and calretinin (CR) immunoreactive neurons in the main olfactory bulb (MOB) of the musk shrew, Suncus murinus, were studied by immunostaining to determine the degree of colocalization of CB and CR, and the relationship of CB and CR to neuron development in the MOB of animals of the order Insectivora. In adults, CB-positive neurons were identified as periglomerular and perinidal cells in the periglomerular region, as superficial short-axon cells in the external plexiform layer, and as four types of interneurons (Cajal, horizontal, Golgi, and bitufted cells) in the mitral cell, internal plexiform, and granule cell layers. CR-positive neurons were identified as projection neurons (tufted and mitral cells) and interneurons (periglomerular, perinidal, and granule cells). On postnatal days 1 and 3, CB-positive neurons revealed numerous processes finely arborized near the somata, and were morphologically unidentifiable. At the same time, CR-positive neurons were identified as young periglomerular and granule cells, and as migrating bipolar cells extending leading processes with growth cones in each layer of the MOB and the subependymal layer between the anterior lateral ventricle and the center of the MOB. On postnatal day 28, mature CB-positive and CR-positive interneurons were distributed in their corresponding layers, whereas migrating CR-positive bipolar cells were rarely detected. No cells colocalized CB and CR. The results suggest that perinidal cells in the shrew MOB may develop postnatally, together with glomerular and granule cells. We suggest that CB is associated with mechanisms of the outgrowth of neuronal processes, whereas CR is involved in mechanisms of cell migration and outgrowth of neuronal processes, in some types of neurons in the developing stage of the shrew MOB.

Age Factors↗
PubMed1996

Liver apoptosis after dimethylnitrosamine administration in shrews.

Female house musk shrews (Suncus murinus, Insectivora) were given a single i.p. dose of 30 mg/kg dimethylnitrosamine (DMN) at 8 weeks of age which was lethal 36 to 48 hrs after dosing. Liver tissues were collected from shrews killed 3, 6, 16, 24 and 36 hrs after treatment, and the sequential development of the lesions was characterized. DMN induced acute centrilobular cell injury. In 6 hrs, a few cells became apoptotic in the centrilobular area; the number increased at 16 hrs and 24 hrs, and was prominent at 36 hrs. There was no inflammatory reaction or necrosis and hemorrhage was not obvious. These apoptotic cells as well as normal appearing cells in the centrilobular area were labeled by the TUNEL method. In both hepatocytes and endothelial cells, apoptosis was confirmed electron microscopically as nuclear chromatin condensation at the periphery with no mitochondria swelling. When an i.p. dose of 10 mg/kg DMN was given twice at 8 and 9 weeks of age, no acute toxicity was induced, and the liver of shrews surviving for 50 weeks of age was normal with no tumor formation. These findings indicate that a single i.p. administration of 30 mg/kg DMN induced severe and fatal toxicity on liver tissues in shrews due to apoptosis, whereas 2 x 10 mg/kg DMN had no carcinogenic effect.

Animals↗
PubMed2004

"Lipotyphlan" phylogeny based on the growth hormone receptor gene: a reanalysis.

From an evolutionary perspective, "insectivores" have been one of the most important mammalian groups for over a century. Morphologists have successively pruned flying lemurs, elephant shrews, and tree shrews from Insectivora, but have retained chrysochlorids, tenrecs, erinaceids, soricids, talpids, and solenodontids in crown-group Lipotyphla. With the appearance of large molecular data sets, the monophyly of Lipotyphla has proved untenable. Rather, an emerging consensus is that Lipotyphla is a diphyletic taxon comprised of two monophyletic groups, Afrosoricida and Eulipotyphla. A recent paper by Malia et al. [Mol. Phylogenet. Evol. 24 (2002) 91-101] challenged this view and argued that "While the data [Growth Hormone Receptor] were unable to support the orders Lipotyphla, Eulipotyphla, and Tenrecoidea [= Afrosoricida] this was most likely due to the polyphyly of these groups and not to problems associated with the gene itself such as saturation or highly divergent sequences em leader " (p. 100). We analyzed Malia et al.'s original GHR data set (at both nuclear and protein level), an expanded GHR data set that included 49 additional sequences, and a concatenated data set that included GHR, BRCA1, vWF, and A2AB for a diverse selection of lipotyphlan taxa. Although protein analyses proved inconclusive, all analyses at the DNA level clearly show that the statement of Malia et al. is erroneous. Indeed, likelihood analyses with GHR and with the concatenated data set provide more support for Eulipotyphla and Afrosoricida than for competing hypotheses. These results also highlight the potential pitfalls of single-gene and parsimony-only analyses.

Animals↗
PubMed2004

Novelties of conception in insectivorous mammals (Lipotyphla), particularly shrews.

In the order Lipotyphla (Insectivora), certain reproductive features differ quite distinctly from the eutherian norms, and are of interest with regard to the evolution of mammalian gamete function and perhaps for questions of lipotyphlan phylogeny. As seen in one or more members of five lipotyphlan families (shrews, moles, hedgehogs, golden moles, tenrecs), these features can involve the configuration of the male tract including the penis, the morphology of the sperm head, the anatomy of the oviduct and the patterns of sperm transport within it, the character of the cumulus oophorus, and the way in which fertilising spermatozoa interact with the eggs. However, the picture is by no means uniform within the order. Reproductive idiosyncrasies occur variously in the different lipotyphlan families, and appear consistently and strikingly in shrews--the group studied most extensively. Compared to the patterns in most Eutheria, the most interesting anomalies in soricids include (a) the regulation of sperm transport to the site of fertilisation by oviduct crypts, whose arrangement can vary even according to species, (b) a circumscribed matrix-free cumulus oophorus that appears essential for fertilisation as the inducer of the acrosome reaction, (c) barbs on the acrosome-reacted sperm head by which it may attach to the zona pellucida. With regard to the bearing such reproductive traits might have on lipotyphlan systematics, the African mouse shrew (Myosorex varius) displays a mix of traits that characterize either crocidurine or soricine shrews, consistent with the proposal that it belongs in a more primitive tribe, Myosoricinae, or subfamily, the Crocidosoricinae, from which the crocidurine and soricine lines probably evolved. Moreover, although elephant shrews are assigned now to a separate order (Macroscelidea), they display several of the unusual reproductive features seen in lipotyphlans, particularly in chrysochlorids and tenrecs. On the other hand, if used as a phylogenetic yardstick, none of the reproductive features described serves to define the Lipotyphla as classically constituted within one order, nor necessarily all the relationships suggested by recent sequencing studies of nuclear and mitochondrial genes.

Animals↗
PubMed1999

Aonchotheca musimon n. sp. (Nematoda : Capillariinae) from the mouflon Ovis musimon in the sub-antarctic Kerguelen archipelago, with comments on the relationships with A. bilobata (Bhalerao, 1933) Moravec, 1982 and other species of the genus.

An intestinal capillariid nematode, Aonchotheca musimon n. sp., is described from Ovis musimon imported into the Kerguelen archipelago (Terres Australes et Antarctiques Françaises). The comparison of this new material with other Aonchotheca spp. is based on the usual characters, i.e. spicule, caudal bursa, number of papillae, stichosome, bacillary bands, shape of the cirrus, and on the length of the ejaculatory duct which appears to be of some phylogenetic value. A. musimon, of which the spicule is 208-230 microm long, is close to A. bilobata, another parasite of bovids, which is redescribed here. It is distinct from this species because the posterior region of the female worm is cylindrical instead of conical, the lateral alae of the male worm are longer, quadrangular and vesicular instead of triangular and smooth, the caudal bursa has a folded dorso-lateral edge, there is a recurrent ventral fold of the cirrus, the slender distal part of the spicule is longer, the oesophagus is shorter in both sexes and the slightly larger eggs have a thicker shell. These two species from bovids and A. murissylvatici from murid rodents, of which the main characters are similar, represent a small group with a very elongate ejaculatory duct (1.9-2.5 mm). This is in contrast to a larger group of species with a short ejaculatory duct (350-600 microm), which are parasites of Chiroptera (A. brosseti, A. chabaudi, A. landauae, A. gabonensis), Insectivora (A. erinacei), mustelid Carnivora (A. putorii, A. mustelorum) and glirid rodents (A. myoxinitelae, A. legerae). A. bovis and A. dessetae, respectively parasites of bovids and lagomorphs, present an ejaculatory duct of intermediary length and do not belong to these groups. Several species are transferred to the genus Aonchotheca: A. kashmirensis (Raina & Kaul, 1982) n. comb., A. legerae (Justine, Ferté & Bain, 1987) n. comb., A. forresteri (Kinsella & Pence, 1987) n. comb., A. chabaudi (Justine, 1989) n. comb., A. landauae (Justine, 1989) n. comb., A. brosseti (Justine, 1989) n. comb., A. gabonensis (Justine, 1989) n. comb. and A. dessetae (Justine, 1990) n. comb.

Animals↗
PubMed2002

Two new species of Heligmoptera Nadtochiy, 1977 (Nematoda: Trichostrongylina: Heligmosomoidea) from myospalacine rodents in China (Gansu), with a redefinition of the genus.

Two species, Heligmoptera giraudouxi n. sp. and H. querei n. sp., are described. These are co-parasites of the small intestine of Myospalax fontanierii in China (Gansu). H. giraudouxi is closely related to the only existing species of the genus, H. myospalaxi (Nadtochiy, 1970), a parasite of Myospalax psilurus in the Primor'e Region of Russia. It is distinguished by the pattern of the left lateral lobe. H. querei differs from the two other species by possessing a long dorsal ray and from H. giraudouxi by the length of the left ala. From a phylogenetic point of view, these three species may form a small clade, adapted to Myospalax spp., derived from related forms in Insectivora, this capture resulting in the appearance of monodelphy.

Animals↗
PubMed1997

Endemic African mammals shake the phylogenetic tree.

The order Insectivora, including living taxa (lipotyphlans) and archaic fossil forms, is central to the question of higher-level relationships among placental mammals. Beginning with Huxley, it has been argued that insectivores retain many primitive features and are closer to the ancestral stock of mammals than are other living groups. Nevertheless, cladistic analysis suggests that living insectivores, at least, are united by derived anatomical features. Here we analyse DNA sequences from three mitochondrial genes and two nuclear genes to examine relationships of insectivores to other mammals. The representative insectivores are not monophyletic in any of our analyses. Rather, golden moles are included in a clade that contains hyraxes, manatees, elephants, elephant shrews and aardvarks. Members of this group are of presumed African origin. This implies that there was an extensive African radiation from a single common ancestor that gave rise to ecologically divergent adaptive types. 12S ribosomal RNA transversions suggest that the base of this radiation occurred during Africa's window of isolation in the Cretaceous period before land connections were developed with Europe in the early Cenozoic era.

Africa↗
PubMed2003

Evidence for gene flow in parasitic nematodes between two host species of shrews.

We describe the genetic structure of populations of the intestinal nematode Longistriata caudabullata (Trichostrongyloidea: Heligmosomidae), a common parasite of short-tailed shrews (genus Blarina, Insectivora: Soricidae). Parasites and hosts were collected from a transect across a contact zone between two species of hosts, Blarina brevicauda and B. hylophaga, in central North America. An 800-base pairs (bp) fragment of the ND4 mitochondrial DNA (mtDNA) gene was sequenced for 28 worms and a 783-bp fragment of the mtDNA control region was analysed for 16 shrews. Phylogenetic analyses of mtDNA sequences revealed reciprocal monophyly for the shrew species, concordant with morphological diagnosis, and supported the idea that the transect cuts through a secondary contact zone between well-differentiated B. brevicauda and B. hylophaga. In contrast to this pattern, the parasitic nematode mtDNA phylogeny was not subdivided according to host affiliation. Genealogical discordance between parasite and host phylogenies suggests extensive gene flow among parasites across the host species boundary.

Animals↗