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Selected AbstractsEVOLUTION OF SUBTERRANEAN DIVING BEETLES (COLEOPTERA: DYTISCIDAE HYDROPORINI, BIDESSINI) IN THE ARID ZONE OF AUSTRALIAEVOLUTION, Issue 12 2003Remko Leys Abstract Calcrete aquifers in arid inland Australia have recently been found to contain the world's most diverse assemblage of subterranean diving beetles (Coleoptera: Dytiscidae). In this study we test whether the adaptive shift hypothesis (ASH) or the climatic relict hypothesis (CRH) is the most likely mode of evolution for the Australian subterranean diving beetles by using a phylogeny based on two sequenced fragments of mitochondrial genes (CO1 and 16S-tRNA-ND1) and linearized using a relaxed molecular clock method. Most individual calcrete aquifers contain an assemblage of diving beetle species of distantly related lineages and/or a single pair of sister species that significantly differ in size and morphology. Evolutionary transitions from surface to subterranean life took place in a relatively small time frame between nine and four million years ago. Most of the variation in divergence times of the sympatric sister species is explained by the variation in latitude of the localities, which correlates with the onset of aridity from the north to the south and with an aridity maximum in the Early Pliocene (five mya). We conclude that individual calcrete aquifers were colonized by several distantly related diving beetle lineages. Several lines of evidence from molecular clock analyses support the CRH, indicating that all evolutionary transitions took place during the Late Miocene and Early Pliocene as a result of aridification. [source] Revisiting a Classification Scheme for U.S.-Mexico Alluvial Basin-Fill AquifersGROUND WATER, Issue 5 2005Barry J. Hibbs Intermontane basins in the Trans-Pecos region of westernmost Texas and northern Chihuahua, Mexico, are target areas for disposal of interstate municipal sludge and have been identified as possible disposal sites for low-level radioactive waste. Understanding ground water movement within and between these basins is needed to assess potential contaminant fate and movement. Four associated basin aquifers are evaluated and classified; the Red Light Draw Aquifer, the Northwest Eagle Flat Aquifer, the Southeast Eagle Flat Aquifer, and the El Cuervo Aquifer. Encompassed on all but one side by mountains and local divides, the Red Light Draw Aquifer has the Rio Grande as an outlet for both surface drainage and ground water discharge. The river juxtaposed against its southern edge, the basin is classified as a topographically open, through-flowing basin. The Northwest Eagle Flat Aquifer is classified as a topographically closed and drained basin because surface drainage is to the interior of the basin and ground water discharge occurs by interbasin ground water flow. Mountains and ground water divides encompass this basin aquifer on all sides; yet, depth to ground water in the interior of the basin is commonly >500 feet. Negligible ground water discharge within the basin indicates that ground water discharges from the basin by vertical flow and underflow to a surrounding basin or basins. The most likely mode of discharge is by vertical, cross-formational flow to underlying Permian rocks that are more porous and permeable and subsequent flow along regional flowpaths beneath local ground water divides. The Southeast Eagle Flat Aquifer is classified as a topographically open and drained basin because surface drainage and ground water discharge are to the adjacent Wildhorse Flat area. Opposite the Eagle Flat and Red Light Draw aquifers is the El Cuervo Aquifer of northern Chihuahua, Mexico. The El Cuervo Aquifer has interior drainage to Laguna El Cuervo, which is a phreatic playa that also serves as a focal point of ground water discharge. Our evidence suggests that El Cuervo Aquifer may lose a smaller portion of its discharge by interbasin ground water flow to Indian Hot Springs, near the Rio Grande. Thus, El Cuervo Aquifer is a topographically closed basin that is either partially drained if a component of its ground water discharge reaches Indian Hot Springs or undrained if all its natural ground water discharge is to Laguna El Cuervo. [source] Host culling as an adaptive management tool for chronic wasting disease in white-tailed deer: a modelling studyJOURNAL OF APPLIED ECOLOGY, Issue 2 2009Gideon Wasserberg Summary 1Emerging wildlife diseases pose a significant threat to natural and human systems. Because of real or perceived risks of delayed actions, disease management strategies such as culling are often implemented before thorough scientific knowledge of disease dynamics is available. Adaptive management is a valuable approach in addressing the uncertainty and complexity associated with wildlife disease problems and can be facilitated by using a formal model. 2We developed a multi-state computer simulation model using age, sex, infection-stage, and seasonality as a tool for scientific learning and managing chronic wasting disease (CWD) in white-tailed deer Odocoileus virginianus. Our matrix model used disease transmission parameters based on data collected through disease management activities. We used this model to evaluate management issues on density- (DD) and frequency-dependent (FD) transmission, time since disease introduction, and deer culling on the demographics, epizootiology, and management of CWD. 3Both DD and FD models fit the Wisconsin data for a harvested white-tailed deer population, but FD was slightly better. Time since disease introduction was estimated as 36 (95% CI, 24,50) and 188 (41,>200) years for DD and FD transmission, respectively. Deer harvest using intermediate to high non-selective rates can be used to reduce uncertainty between DD and FD transmission and improve our prediction of long-term epidemic patterns and host population impacts. A higher harvest rate allows earlier detection of these differences, but substantially reduces deer abundance. 4Results showed that CWD has spread slowly within Wisconsin deer populations, and therefore, epidemics and disease management are expected to last for decades. Non-hunted deer populations can develop and sustain a high level of infection, generating a substantial risk of disease spread. In contrast, CWD prevalence remains lower in hunted deer populations, but at a higher prevalence the disease competes with recreational hunting to reduce deer abundance. 5Synthesis and applications. Uncertainty about density- or frequency-dependent transmission hinders predictions about the long-term impacts of chronic wasting disease on cervid populations and the development of appropriate management strategies. An adaptive management strategy using computer modelling coupled with experimental management and monitoring can be used to test model predictions, identify the likely mode of disease transmission, and evaluate the risks of alternative management responses. [source] Modes and mechanisms of speciation in pteridophytes: Implications of contrasting patterns in ferns representing temperate and tropical habitatsPLANT SPECIES BIOLOGY, Issue 3 2000Christopher H. Haufler Abstract Discovering how biological diversification results in species is one of the primary challenges facing evolutionary biologists. In the ferns, evidence indicates that dissimilar speciation modes and mechanisms may differentiate some temperate and tropical groups. The Polypodium sibiricum group contains three related diploid species that all inhabit rock outcrops in temperate forests. Although differing lettle in gross leaf morphology and joined by the distinctive morphological synapomorphy of sporangiasters, these three species have an average interspecific genetic identity developed from isozymic com-parisons of only 0.460. A likely mode of speciation is that periodic glaciation pushed Po. sibiricum populations south and, with the retreat of the glaciers, southern populations persisted, evolved diagnostic traits, and ultimately erected postzygotic barriers to interbreeding. This hypothesis follows a classic allopatric speciation model and interspecific distinctions may have been reinforced through contact mediated by subsequent ice ages. In contrast, a monophyletic group of four diploid, epiphytic Pleopeltis species centered in Mexico has an isozymically-determined average interspecific genetic identity value of 0.849. In spite of this high value, these species show greater morphological discrimination than do the Polypodium species. Although the species ranges overlap, they appear to occupy ecologically discrete habitats. These Pleopeltis species may have originated through adaptation to different ecological zones and developed individual morphologies in the process. The high interspecific genetic identity values among the Pleopeltis species suggest a relatively recent and/or rapid process. These hypotheses should be tested by further biosystematic investigations and the discovery of additional monophyletic assemblages with similar patterns of speciation. [source] Perinatal imaging findings of inherited Sotos syndromePRENATAL DIAGNOSIS, Issue 10 2002Chih-Ping Chen Abstract Objectives Although most cases of Sotos syndrome are sporadic, familial cases have been described. In familial cases, the most likely mode of inheritance is autosomal dominant with variable expressivity. We present the perinatal imaging findings of an inherited case. Case This was the second pregnancy of a 32-year-old woman with Sotos syndrome. She had given birth to her first child with macrocephaly, ventriculomegaly, macrocisterna magna and neonatal death at 28 weeks' gestation. During this pregnancy, prenatal ultrasonography at 18 weeks' gestation showed only mild dilatation of lateral ventricles. The pregnancy was uneventful until 31 weeks' gestation when fetal macrocephaly, right hydronephrosis, and polyhydramnios began to develop. At 33 weeks' gestation, dilatation of the third ventricle and fetal overgrowth were obvious. At 34 weeks' gestation, macrodolichocephaly, hypoplasia of the corpus callosum, enlargement of the lateral ventricles with prominent occipital horns, and macrocisterna magna were noted. At 36 weeks' gestation, a male baby was delivered with macrodolichocephaly, frontal bossing and a facial gestalt of Sotos syndrome. Birth weight was 3822 g, length 55 cm, and occipitofrontal head circumference 41 cm (all > 97th centile). The magnetic resonance imaging (MRI) scans demonstrated enlargement of the lateral ventricles, the trigones, and the occipital horns, hypoplasia of the corpus callosum, a persistent cavum septum pellucidum and cavum vergae, and macrocisterna magna. Conclusions Fetuses at risk for Sotos syndrome may present abnormal sonographic findings of the brain and the skull in association with overgrowth, unilateral hydronephrosis and polyhydramnios in the third trimester. Perinatal MRI studies aid in confirmation of the diagnosis. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||