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At least 739 records · Page 41Linked to original sources
PubMed1989

Sonography of the simple and complicated ipsilateral fused kidney.

Anomalies of renal fusion and their sonographic findings can be straightforward or quite complex. Sonograms of eight cases of simple and complicated anomalies of renal fusion in pediatric patients are reviewed to determine characteristic sonographic findings in such cases. The correct diagnosis can be suspected by evaluation of the following parameters: (1) the echoic texture of the renal "mass"; (2) the differential orientation of the renal pelves; (3) the content of the contralateral renal fossa; (4) the size of the ipsilateral kidney; (5) extension of the isthmus medially anterior to the spine; and (6) presence of a deep anteroposterior notch. Utilizing these parameters, a rationale for diagnosis and for selecting the appropriate sequence of further studies is suggested.

Child↗
PubMedDate not supplied

[Reaching behavior of rats during realization of a lateralized motor food skill].

Adult Wistar rats were trained to obtain food pellets from a narrow horizontal tube with a preferred forepaw. The feeder was equipped with five photoelectric sensors with 5-mm spacing. The following parameters were recorded: total number of movements performed for a given task, amplitude (depth) of each movement, number of anticipatory movements performed with different amplitudes, and amplitude of a successful movement. It was shown that in rats with good skill acquisition, a successful food extraction was preceded by a series of differently organized sequence of preliminary movements. In some rats, such a series consisted of initial non-deep attempts followed by movements with high amplitude, whereas in other animals, it was represented, mainly, by deep attempts. Both groups of animals terminated the series by grasping and extracting food from a long distance. It is suggested that the observed organizations of the lateralized food-getting behavior of rats under the given experimental conditions represent fixed (stereotyped) action patterns.

Animals↗
PubMed1990

The structure and ultrastructure of the rostral cartilage in the spiny eel, Macrognathus siamensis (Teleostei: Mastacembeloidei).

An elastic, cell-rich cartilage provides flexible support to the highly mobile, rostral tentacle of the mastacembelid, Macrognathus siamensis. Active movement of the tentacle is effected by skeletal muscles, the muscular bellies of which are located outside the organ. The tentacle returns to its original shape by elastic recoil. The cartilage resembles plant supporting tissue and the cartilages of certain invertebrates. It is surrounded by a thick perichondrium and articulates at a synovial joint with the supraethmoid. The chondrocytes are large and shrunken within lacunae. They contain glycogen and cytoplasmic stores of RNA. The matrix is reduced to thin seams between adjacent cells, and stains strongly with alcian blue and a variety of elastic stains. Parts of the matrix are trilaminar, and such an appearance recalls the distinction between the primary cell walls of adjacent plant cells and the intervening middle lamella. The perichondrium consists of an alternating sequence of cells, circularly arranged collagen fibres and a foamy, amorphous material of unknown composition. Deep to the perichondrium, the chondrocytes are packed with intermediate filaments. Membrane-bound organelles are not prominent, though mitochondria are located at the periphery of the cell. The ultrastructural similarities between these chondrocytes and those of hyaline-cell cartilage (chondroid) support the contention that Schaffer's concept of a rigid distinction between 'true' cartilage and 'chondroid' is no longer tenable. The matrix is devoid of collagen and is most distinctive. In the immediate vicinity of the cells it consists of matrix granules and matrix fibers but, where a trilaminar appearance is easily discernible, there is a central zone that consists of large masses of amorphous material that is presumed to contain elastin. Such amorphous material has not previously been seen in any teleostean elastic tissue. By contrast, elastic system fibres, readily demonstrable elsewhere in teleosts, are conspicuously absent.

Animals↗
PubMed1997

[An apparently sporadic case with spinocerebellar ataxia type 1 (SCA1)].

We reported a sporadic case with late onset SCA1. There was no family history of neurological diseases. His parents had been healthy until they died at the age of 77 and 89 years, respectively. The patient noticed gait disturbance at age of 60. Thereafter, he gradually developed cerebellar ataxia, hyporeflexia, mild atrophy of the facial and limb muscles and moderate deep sensory disturbance. MRI of the brain showed moderate atrophy of the cerebellum and brainstem. Sequencing analysis of SCA1 gene demonstrated that the patient had an expanded allele with 40 CAG repeats and no CAT interruption. Consequently, he was diagnosed as having SCA1. These results suggest the possibility that among apparently sporadic cases with cerebellar ataxia, there are some cases of SCA1 with mild CAG repeat expansion.

Atrophy↗
PubMedDate not supplied

The effects of patterned breathing and continuous positive airway pressure on cardiovascular regulation in healthy volunteers.

1. Although the increased heart rate variability in healthy subjects in association with slow patterned breathing and continuous positive airway pressure is well documented, there is no general agreement regarding the underlying mechanism. The arterial baroreceptor stimulation due to greater blood pressure variability, the stimulation of pulmonary stretch and low pressure baroreceptors can play important role in this phenomenon. 2. In order to assess the interplay between blood pressure and heart rate changes we have studied nine healthy volunteers (mean age was 22 yrs. range 19-24), by applying 6/min patterned breathing, and continuous positive airway pressure of 10 cm of water. ECG and finger blood pressure (Finapres 2300) was continuously recorded. The oscillation amplitude of R-R intervals were analysed as well as the time and frequency domain indexes of heart rate variability. The oscillation amplitude and the corresponding frequency domain components of systolic blood pressure were also calculated. 3. The forced deep breathing caused significant increase in heart rate variability as indicated by time and frequency domain analysis of R-R intervals (LF HRV ms2: spontaneous: 777.40 +/- 526.1, patterned breathing 6828.00 +/- 5468.0). The application of CPAP in the same rhythm during patterned breathing resulted in further enhancement in heart rate variability (LF HRV ms2: 9052.00 +/- 4533.0). The analysis of the same frequency domain components of systolic blood pressure showed marked elevation of the total and low frequency power during patterned breathing. (LF BPV mm Hg2: spontaneous: 8.24 +/- 6.2, patterned breathing: 16.22 +/- 9.7). Applying CPAP with the same breathing pattern elicited further significant increment in systolic blood pressure fluctuation (LF BPV mm Hg2: deep breathing + CPAP: 27.11 +/- 9.8). The baroreflex sensitivity as calculated from spontaneous HR and BP sequences was 11.66 +/- 2.9 at baseline and increased to 17.66 +/- 6.1 and changed to 15.22 +/- 3.2 with the addition of patterned breathing and CPAP, respectively. 4. Our findings indicate that the heart rate and blood pressure responses to slow patterned breathing may be interpreted as consequences of an altered baroreflex sensitivity. In contrast the active breathing with CPAP exerts mechanical effects which in turn present an augmented systemic baroreflex trigger, however, the baroreflex sensitivity remains unchanged.

Adult↗
PubMed2005

Migraine and cerebral white matter lesions: when to suspect cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

BACKGROUND: Patients with migraine are at an increased risk for white matter lesions, typically multiple, small, punctate hyperintensities in the deep or periventricular white matter, best observed on magnetic resonance imaging utilizing T2-weighted or FLAIR sequences. The underlying pathogenesis of white matter lesions in migraineurs is unknown, and the lesions are usually nonspecific and of unclear clinical significance. REVIEW SUMMARY: Often the presence of white matter lesions causes uncertainty for physicians and anxiety for patients and may lead to a variety of diagnostic tests and treatments. Occasionally, white matter lesions may represent a secondary cause for headaches such as CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). CADASIL is underrecognized and underdiagnosed; it should be suggested by (i) 1 or more of recurrent subcortical ischemic strokes (especially before age 60 and in the absence of vascular risk factors), migraine (especially with aura, including atypical or prolonged auras) and/or early cognitive decline or subcortical dementia; (ii) bilateral, multifocal, T2/FLAIR hyperintensities in the deep white matter and periventricular white matter with lesions involving the anterior temporal pole, external capsule, basal ganglia, and/or pons; and (iii) an autosomal-dominant family history of migraine, early-onset stroke, or dementia. The clinical spectrum of CADASIL is broad, and there is a poor genotype-phenotype correlation. In certain individuals or families, migraine may be the only clinical manifestation. CONCLUSIONS: While the prevalence of nonspecific white matter lesions in migraineurs is increased, the white matter lesions may occasionally represent a secondary cause for headache such as CADASIL. Greater awareness of the unique clinical, neuroimaging, and pathologic features, as well as the availability of diagnostic genetic testing, should enhance the recognition and diagnosis of this fascinating condition.

Brain↗
PubMed2001

Superficial fibromatoses are genetically distinct from deep fibromatoses.

Whereas deep fibromatoses (abdominal, extra-abdominal, mesenteric) display locally aggressive behavior, superficial fibromatoses typically remain small and less likely to recur despite essentially identical morphology. Somatic beta-catenin or APC gene mutations have been reported in < or =74% of sporadic deep fibromatoses and in virtually 100% of Gardner syndrome-associated fibromatoses, whereas genetic events in superficial fibromatoses remain less well characterized. We performed immunohistochemical staining for beta-catenin on 29 superficial fibromatoses (22 palmar, 5 plantar, 1 penile, and 1 infantile digital fibromatosis) and 5 deep fibromatoses. Mutations of beta-catenin and APC genes were analyzed in cases of superficial fibromatoses by direct DNA sequencing of the beta-catenin gene on Exon 3 encompassing the GSK-3 36 phosphorylation region and of the APC gene on the mutation cluster region. Nuclear accumulation of beta-catenin was present in 86% (25/29) of superficial fibromatosis cases ranging from 5 to 100% of nuclei (mean, 13%; median, 10%), though in a minority of nuclei in most examples. Deep fibromatoses had 60 to 100% nuclear staining in all five cases. No somatic mutations of beta-catenin or APC genes were identified in any of the superficial fibromatoses. In contrast to deep fibromatoses, superficial fibromatoses lack beta-catenin and APC gene mutations; the significance of focal nuclear beta-catenin accumulation is unclear. This difference may account inpart for their divergent clinical manifestations despite their morphologic resemblance to deep fibromatoses.

Adult↗
PubMed2003

Endemic diversification of the monophyletic cottoid fish species flock in Lake Baikal explored with mtDNA sequencing.

In the ancient Lake Baikal in East Siberia, cottoid fishes have diversified into an endemic flock of 33 species. From an ancestral shallow-water, benthic life-style, Baikalian cottoids have shifted to deep-water life in environments even below 1500 m, and also colonized the pelagic habitat. We examined phylogenetic relationships among 22 Baikalian and 10 extra-Baikalian cottoid taxa using a total of 2822 bp of mitochondrial DNA sequence, from complete sequences of ATPase 8 and 6 and cytochrome b genes and the control region. Unlike in earlier studies, we found strong support for a monophyly of the whole endemic Baikalian cottoid diversity. The Baikalian clade, currently assigned to three families and 12 genera, appears to be nested within the Holarctic freshwater genus Cottus. In the molecular phylogeny, all but one of the current Baikalian genera formed well-supported monophyletic groups. However, the topology was inconsistent with the present morphology-based familial subdivision; particularly in positioning the genus Batrachocottus of Cottidae within Abyssocottidae. The branching order of the Baikalian genera could not be resolved completely, however; short basal branches indicate rapid diversification early in the history of the species flock. Using synonymous divergence rates from other fish species for calibration, the diversification of the Baikalian cottoids seems to have started in the Pliocene or early Pleistocene.

Animals↗
PubMed2000

Mutational investigation of the specificity determining region of the Src SH2 domain.

SH2 domains are protein modules which bind tyrosine phosphorylated sequences in many signaling pathways. These domains contain two regions with specialized functions: residues in one region form a deep pocket into which the phosphotyrosine of the target inserts, while the other region contains the so-called "specificity determining residues" which interact with the three residues C-terminal to the phosphotyrosine in the target. Here, titration calorimetry and site-directed mutagenesis have been used to probe the importance of eight specificity determining residues of the SH2 domain of the Src kinase involved in contacts with its tyrosine phosphorylated consensus peptide target (sequence pYEEI where pY indicates a phosphotyrosine). Mutating six of these eight residues to Ala individually, resulted in a threefold or less loss in binding affinity; hence the majority of the residues in the specificity determining region are by themselves of minimal importance for binding. Two residues were found to have significant effects on binding: Tyr betaD5 and Lys betaD3. Tyr betaD5 was the most crucial residue as evidenced by the 30-fold loss in affinity when Tyr betaD5 is mutated to Ile. However, while this mutation eliminated the specificity of the Src SH2 domain for the pYEEI peptide sequence, it was not sufficient to switch the specificity of the Src SH2 domain to that of a related SH2 domain which has an Ile at the betaD5 position. Mutation of Lys betaD3 to an Ala residue resulted in a modest reduction in binding affinity (sevenfold). It is interesting that this mutation resulted in a change of specificity affecting the selection of the +1 position residue C-terminal to the phosphotyrosine. Except for the Lys betaD3-+1 Glu interaction which is significantly coupled, only weak energetic coupling was observed across the binding interface, as assessed using double mutant cycles. The results of this study suggest that interactions involving the specificity determining region of SH2 domains may be insufficient by themselves to target single SH2 domains to particular phosphorylated sites.

Amino Acid Substitution↗
PubMed2002

Prokaryotic phylogenetic diversity and corresponding geochemical data of the brine-seawater interface of the Shaban Deep, Red Sea.

The interface between the hypersaline brine and the overlying sea-water (brine-seawater interface) of the Shaban Deep, northern Red Sea was investigated for the presence of microorganisms using the 16S rRNA gene as a molecular marker. Samples of the south and east basin (depth: 1331 m and 1332 m respectively) were selected to ascertain the microbial diversity of this extreme and, so far, unexplored environment. Phylogenetic analysis revealed novel lineages within the Bacteria, the Crenarchaeota and the Euryarchaeota. Novel representatives of the KB1 sequence group (Eder et al., 1999 Arch Microbiol 172: 213-218) were detected indicating a widespread distribution of the corresponding Bacteria in Deep Sea brine pools. Our results contribute to the understanding of the hitherto unknown microbial diversity at the chemical gradient of the Shaban Deep, and suggest the presence of novel Bacteria and Archaea thriving under extreme environmental conditions.

Archaea↗
PubMed2001

Frequency of haemoglobin desaturation with the use of succinylcholine during rapid sequence induction of anaesthesia.

BACKGROUND: The perceived safety of the use of succinylcholine is based on the fact that recovery from its effects will occur before oxygen desaturation occurs in case of failure to intubate or ventilate. The purpose of this study was to examine the incidence of oxygen desaturation after the use of succinylcholine prior to resumption of spontaneous ventilation following four different preoxygenation techniques. METHODS: Twenty-five patients each were randomly allocated to preoxygenation with 4 deep breaths of 100% oxygen or by breathing oxygen for 1, 3 or 5 min following which they received a rapid sequence induction of anaesthesia with fentanyl 1 microg kg(-1), a sleep dose of thiopentone and succinylcholine 1 mg kg(-1). Oxygen saturation was monitored continuously using a finger probe. Ventilation was not assisted unless the saturation decreased to <or=90%. RESULTS: Eleven out of the 100 patients had a decrease in their oxygen saturation to <or=90% before the resumption of effective spontaneous ventilation irrespective of the technique of preoxygenation. CONCLUSION: We conclude that use of succinylcholine may not always prevent desaturation if there is a failure to intubate and ventilate during a rapid sequence induction of anaesthesia.

Adolescent↗
PubMed2001

Phylogeography of the dusky shrew, Sorex monticolus (Insectivora, Soricidae): insight into deep and shallow history in northwestern North America.

Phylogenetic relationships among the dusky shrew (Sorexmonticolus) and eight related species (S. bairdi, S. bendirii, S. neomexicanus, S.ornatus, S. pacificus, S. palustris, S. sonomae and S.vagrans) were assessed using sequences from the mitochondrial cytochrome b gene (801 bp). Analyses using parsimony and maximum likelihood revealed significant molecular variation not reflected in previous morphological studies of these species. Conversely, three morphologically defined species (S.bairdi, S.neomexicanus and S.pacificus) were poorly differentiated. Sorexornatus and S.vagrans represented basal taxa for a more inclusive group that included: (i) a widespread Continental clade containing S.monticolus (Arizona to Alaska, including S. neomexicanus); (ii) a Coastal clade containing S.monticolus (Oregon to south-east Alaska, including S. bairdi and S. pacificus); (iii) the semiaquatic species (S. bendirii and S. palustris); and (iv) S.sonomae. Additional subdivision was observed within the Continental clade corresponding to populations from the northern and southern Rocky Mountains. Average uncorrected sequence divergence between the Coastal and Continental clades was 5.3% (range 4.5-6.2%), which exceeds many interspecific comparisons within this species complex and within the genus Sorex. Lack of resolution of internal nodes within topologies suggests a deep history of rapid diversification within this group. Late Pleistocene/Holocene glacial perturbations are reflected in the shallow phylogeographic structure within these clades in western North America. Our results suggest also that S. monticolus is not monophyletic under current taxonomic nomenclature. This perspective on phylogeographic history was developed within a growing comparative framework for other organisms in western North America.

Animals↗
PubMed1995

Potential for increasing conspicuity of short-T1 lesions in the brain using magnetisation transfer imaging.

We investigated the feasibility of using T1-weighted magnetisation transfer sequences to generate tissue contrast and increase the conspicuity of short-T1 areas within the brain. We imaged two normal volunteers with and without saturating off-resonance radiofrequency irradiation at a range of repetition times (TR 200-760 ms). T1 values and magnetisation transfer ratios for white matter and deep grey matter were calculated. We studied eight patients with intracranial lesions showing short-T1 areas, using mildly T1-weighted sequences with and without magnetisation transfer contrast. Lesion numbers, areas and signal intensities were measured and lesion-to-background contrast was calculated. Comparison was made with conventional T1-weighted spin-echo images. In the normal volunteers, contrast between the thalamus, caudate and lentiform nuclei and white matter showed striking visual differences, with magnetisation transfer weighing, with decreasing TR. In all patients, short-T1 lesions were seen more clearly on magnetisation transfer-weighted images, with significant increase in lesion number, area and contrast, when compared with conventional T1-weighted scans.

Adult↗
PubMed2002

Islands within an island: phylogeography and conservation genetics of the endangered Hawaiian tree snail Achatinella mustelina.

Mitochondrial DNA (mtDNA) sequences were used to evaluate phylogeographic structure within and among populations of three endangered Hawaiian tree snail species (n = 86). The primary focus of this investigation was on setting conservation priorities for Achatinella mustelina. Limited data sets for two additional endangered Hawaiian tree snails, A. livida and A. sowerbyana, were also developed for comparative purposes. Pairwise genetic distance matrices and phylogenetic trees were generated, and an analysis of molecular variance was performed on 675-base pair cytochrome oxidase I gene sequences from multiple populations of Hawaiian tree snails. Sequence data were analysed under distance-based maximum-likelihood, and maximum-parsimony optimality criteria. Within the focal species, A. mustelina, numbers of variable and parsimony informative sites were 90 and 69, respectively. Pairwise intraspecific mtDNA sequence divergence ranged from 0 to 5.3% in A. mustelina, from 0 to 1.0% in A. livida and from 0 to 1.9% in A. sowerbyana. For A. mustelina, population genetic structure and mountain topography were strongly correlated. Maximum genetic distances were observed across deep, largely deforested valleys, and steep mountain peaks, independent of geographical distance. However, in certain areas where forest cover is presently fragmented, little mtDNA sequence divergence exists despite large geographical scales (8 km). Genetic data were used to define evolutionarily significant units for conservation purposes including decisions regarding placement of predator exclusion fences, captive propagation, re-introduction and translocation.

Animals↗
PubMed2003

Application of denaturing gradient gel electrophoresis (DGGE) to the analysis of microbial communities of subgingival plaque.

OBJECTIVES: Denaturing gradient gel electrophoresis (DGGE) was applied to the microbiologic examination of subgingival plaque. MATERIALS AND METHODS: The PCR primers were designed from conserved nucleotide sequences on 16S ribosomal RNA gene (16SrDNA) with GC rich clamp at the 5'-end. Polymerase chain reaction (PCR) was performed using the primers and genomic DNAs of typical periodontal bacteria. The generated 16SrDNA fragments were separated by denaturing gel. RESULTS: Although the sizes of the amplified DNA fragments were almost the same among the species, 16SrDNAs of the periodontal bacteria were distinguished according to their specific sequences. The microflora of clinical plaque samples were profiled by the PCR-DGGE method, and the dominant 16SrDNA bands were cloned and sequenced. Simultaneously, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia were detected by an ordinary PCR method. In the deep periodontal pockets, the bacterial community structures were complicated and P. gingivalis was the most dominant species, whereas the DGGE profiles were simple and Streptococcus or Neisseria species were dominant in the shallow pockets. The species-specific PCR method revealed the presence of A. actinomycetemcomitans, P. gingivalis and P. intermedia in the clinical samples. However, corresponding bands were not always observed in the DGGE profiles, indicating a lower sensitivity of the DGGE method. CONCLUSION: Although the DGGE method may have a lower sensitivity than the ordinary PCR methods, it could visualize the bacterial qualitative compositions and reveal the major species of the plaque. The DGGE analysis and following sequencing may have the potential to be a promising bacterial examination procedure in periodontal diseases.

5' Flanking Region↗
PubMedDate not supplied

Small subunit ribosomal DNA suggests that the xenophyophorean Syringammina corbicula is a foraminiferan.

Xenophyophorea are giant deep-sea rhizopodial protists of enigmatic origins. Although species were described as Foraminifera or sponges in the early literature, the xenophyophoreans are currently classified either as a class of Rhizopoda or an independent phylum. To establish the phylogenetic position of Xenophyophorea, we analysed the small subunit (SSU) rRNA gene sequence of Syringammina corbicula Richardson, a newly described xenophyophorean species from the Cape Verde Plateau. The SSUrDNA analyses showed that S. corbicula is closely related to Rhizammina algaeformis, a tubular deep-sea foraminiferan. Both species branch within a group of monothalamous (single-chambered) Foraminifera, which include also such agglutinated genera as Toxisarcon, Rhabdammina, and Saccammina, and the organic-walled genera Gloiogullmia and Cylindrogullmia. Our results are congruent with observations of similar cytoplasmic organisation in Rhizammina and Syringammina. Thus, the Xenophyophorea appear to be a highly specialised group of deep-sea Foraminifera.

Animals↗
PubMed1994

Phylogeny of Drosophila and related genera inferred from the nucleotide sequence of the Cu,Zn Sod gene.

The phylogeny and taxonomy of the drosophilids have been the subject of extensive investigations. Recently, Grimaldi (1990) has challenged some common conceptions, and several sets of molecular data have provided information not always compatible with other taxonomic knowledge or consistent with each other. We present the coding nucleotide sequence of the Cu,Zn superoxide dismutase gene (Sod) for 15 species, which include the medfly Ceratitis capitata (family Tephritidae), the genera Chymomyza and Zaprionus, and representatives of the subgenera Dorsilopha, Drosophila, Hirtodrosophila, Scaptodrosophila, and Sophophora. Phylogenetic analysis of the Sod sequences indicates that Scaptodrosophila and Chymomyza branched off the main lineage before the major Drosophila radiations. The presence of a second intron in Chymomyza and Scaptodrosophila (as well as in the medfly) confirms the early divergence of these two taxa. This second intron became deleted from the main lineage before the major Drosophila radiations. According to the Sod sequences, Sophophora (including the melanogaster, obscura, saltans, and willistoni species groups) is older than the subgenus Drosophila; a deep branch splits the willistoni and saltans groups from the melanogaster and obscura groups. The genus Zaprionus and the subgenera Dorsilopha and Hirtodrosophila appear as branches of a prolific "bush" that also embraces the numerous species of the subgenus Drosophila. The Sod results corroborate in many, but not all, respects Throckmorton's (King, R.C. (ed) Handbook of Genetics. Plenum Press, New York, pp. 421-469, 1975) phylogeny; are inconsistent in some important ways with Grimaldi's (Bull. Am. Museum Nat. Hist. 197: 1-139, 1990) cladistic analysis; and also are inconsistent with some inferences based on mitochondrial DNA data. The Sod results manifest how, in addition to the information derived from nucleotide sequences, structural features (i.e., the deletion of an intron) can help resolve phylogenetic issues.

Animals↗
PubMed2001

Phylogeography of the yucca moth Tegeticula maculata: the role of historical biogeography in reconciling high genetic structure with limited speciation.

Tegeticula maculata is one of the most ancient and morphologically variable lineages within the yucca moths, yet has apparently undergone little diversification in comparison with much younger yucca moth lineages that have rapidly diversified. A phylogeographic approach was used to determine the number of independent lineages within T. maculata and to examine whether these patterns corresponded with morphological differences between its subspecies maculata and extranea. Phylogenetic analysis of mitochondrial DNA sequence variation indicated that the two subspecies are in separate clades, but there was also an equally deep split within subspecies maculata. There was no evidence for gene flow among regions and there was considerable substructure within clades. The phylogeographic structure of moth populations among and within subspecies can be explained in part by historical biogeographic boundaries and increasingly patchy postglacial distribution of the exclusive host plant, Hesperoyucca whipplei. Local specialization and co-adaptation would be possible in the absence of apparent gene flow, yet gross morphological divergence is limited to the very old split between the subspecies. Sorting of ancient mitochondrial lineages followed by local genetic differentiation may explain the pattern of high genetic structure with limited speciation.

Animals↗