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21.
Climatic fluctuations and orogenesis as motors for speciation in East Africa: case study on Parepistaurus Karsch, 1896 (Orthoptera) 下载免费PDF全文
CLAUDIA HEMP SIEGFRIED KEHL OLIVER SCHULTZ JOHANN W. WÄGELE ANDREAS HEMP 《Systematic Entomology》2015,40(1):17-34
Mechanisms of speciation of flightless grasshoppers in mountainous and coastal East Africa are inferred considering (i) phylogenies estimated with a combination of molecular markers (16S rRNA locus, COI and H3), (ii) ecological data and (iii) the geographic distribution of Parepistaurus species. The study suggests that coastal taxa of Parepistaurus belong to ancestral lineages from which evolved the high diversity of species found in the Eastern Arc Mountains of Tanzania and Kenya, which are geologically ancient mountain formations. Network analyses and a molecular clock approach, calibrated with the geological age of the volcanoes, suggested that speciation was boosted by climatic fluctuations affecting large areas of East Africa. With the aridification beginning 2.8 Ma, forest taxa were isolated due to forest fragmentation and populations were separated by extended grasslands, which are avoided by Parepistaurus species. However, a humid period between 2.7 and 2.5 Ma triggered a spread of coastal taxa along the Eastern Arc Mountains. Forests expanded again and riparian vegetation along rivers draining into the Indian Ocean probably served as corridors for the dispersal of coastal taxa to the hinterland. The inland volcanoes such as Mount Kilimanjaro are therefore good time markers because their geological age is known, limiting the available time for speciation processes of mountainous Parepistaurus in the area to a maximum of about 1–2 Ma. A third humid but cold period between 1.1 and 0.9 Ma probably further boosted the spread of several flightless and montane‐adapted Orthoptera taxa. 相似文献
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BIANCA ETHEL GUTIÉRREZ-AMAVIZCA ANDREAS GAL ROCÍO ORTÍZ-OROZCO ULRICH ORTH ERNESTO PRADO MONTES DE OCA JAIME PAUL GUTIÉRREZ-AMAVIZCA LUIS E. FIGUERA 《Journal of genetics》2017,96(1):161-164
Fabry disease (FD) is a lysosomal storage disorder, which develops due to a deficiency in the hydrolytic enzyme, α-galactosidase A (α-Gal A). Alpha-Gal A hydrolyzes glycosphingolipid globotriaosylceramide (Gb3), and an α-Gal A deficiency leads to Gb3 accumulation in tissues and cells in the body. This pathology is likely to involve multiple systems, but it is generally considered to affect primarily vascular endothelium. In this study, we investigated mutations in the GLA gene, which encodes α-Gal A, in Mexican families with FD. We included seven probands with FD that carried known mutations. We analysed pedigrees of the probands, and performed molecular screening in 65 relatives with the potential of carrying a GLA mutation. Five mutations (P40S, IVS4 +4, G328V, R363H, R404del) were detected in seven unrelated Mexican families with the classic FD phenotype. Of the 65 relatives examined, 42 (64.6%) had a GLA gene mutation. In summary, among seven Mexican probands with FD, 65 relatives were at risk of carrying a known GLA mutation, and molecular screening identified 42 individuals with the mutation. Thus, our findings showed that it is important to perform molecular analysis in families with FD to detect mutations and to provide accurate diagnoses for individuals that could be affected. 相似文献
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MATHIAS HARZHAUSER OLEG MANDIC WERNER E. PILLER† MARKUS REUTER† ANDREAS KROH 《Palaeontology》2008,51(1):199-213
Abstract: Two new tridacnine species are described from the Chattian and Aquitanian of the Arabian Peninsula. For these, the new names Omanidacna eos gen. et sp. nov. and Tridacna evae sp. nov. are erected. Omanidacna is interpreted as an Oligocene ancestor of Hippopus , being the oldest record of this tridacnine lineage. The Aquitanian Tridacna evae is the first occurrence of the genus Tridacna . These Arabian taxa imply that the modern tridacnine lineages are rooted in the Palaeogene and early Neogene of the East African-Arabian Province, although their Eocene ancestors, such as Byssocardium , are Western Tethyan taxa. During the Neogene they successfully settled the Indo-Polynesian Province and became typical elements of the entire Indo-West Pacific Region. The tridacnines are thus an example of a successive transformation and gradual eastward dispersal of an originally Tethyan element contributing to late Neogene diversity in the Indo-West Pacific. 相似文献
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IVO KARAMAN NASERA HAMMOUTI DRAGAN PAVIĆEVIĆ ANDREAS KIEFER MLADEN HORVATOVIĆ ALFRED SEITZ 《Zoological Journal of the Linnean Society》2011,163(4):1035-1063
We present a revision of the genus Troglophilus in the western part of the Balkan Peninsula based on morphological and genetic analysis, and provide distribution data for the species. The results of these analyses reduced the number of the known taxa within the genus Troglophilus in this area to five valid species: Troglophilus cavicola ( Kollar, 1833 ), Troglophilus neglectus Krauss, 1879 , Troglophilus ovuliformis Karny, 1907 , Troglophilus brevicauda Chopard, 1934, and Troglophilus lazaropolensis Karaman, 1958. A new species Troglophilus zorae sp. nov. is described and Troglophilus neglectus serbicus Maran, 1958, Troglophilus neglectus vlasinensis Maran, 1958, Troglophilus bukoviki Karaman, 1968 and Troglophilus pretneri Us, 1970 are synonymized. The distribution pattern of the western Balkan species supports a general east?west migration route. We also determined the centres of origin and spreading directions of particular species according to the distribution of the taxa and the structure of the haplotypes. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 1035–1063. 相似文献
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Nitrate Uptake and Reduction of Aseptically Cultivated Spruce Seedlings, Picea abies (L.) Karst 总被引:2,自引:0,他引:2
Spruce (Picea abies (L.) Karst.) seedlings were asepticallycultivated and the effects of different N-nutrition on net uptakeand reduction of nitrate were investigated. The characteristicsof nitrate uptake were calculated, Ks as 0?2 mol m3 andVmax as 18 µmol g1 d1. Low pH, and Al3+ in the medium caused adecrease in nitrate uptake rate. An in vivo assay was set upwhich allowed the measurement of NRA in both roots and needlesof spruce seedlings. The in vivo nitrate reductase activitywas repressed by ammonium and stimulated by nitrate. Nitratereduction was similar to nitrate uptake, negatively affectedby low pH and ammonium. Therefore, a limited N-supply to spruceseemed to occur when pH was low in the rhizosphere combinedwith the presence of Al3+ and . Key words: Spruce, nitrate uptake, nitrate reduction 相似文献
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The concept of need is often proposed as providing an additional or alternative criterion to cost‐effectiveness in making allocation decisions in health care. If it is to be of practical value it must be sufficiently precisely characterized to be useful to decision makers. This will require both an account of how degree of need for an intervention is to be determined and a prioritization rule that clarifies how degree of need and the cost of the intervention interact in determining the relative priority of the intervention. Three common features of health care interventions must be accommodated in a comprehensive theory of need: the probabilistic nature of prognosis (with and without the intervention); the time course of effects; and the fact that the most effective treatments often combine more than one intervention. These common features are problematic for the concept of need. We outline various approaches to prioritization on the basis of need and argue that some approaches are more promising than others. 相似文献
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Chloroplast protrusions in leaves of Ranunculus glacialis L. respond significantly to different ambient conditions,but are not related to temperature stress 下载免费PDF全文
The occurrence of chloroplast protrusions (CPs) in leaves of Ranunculus glacialis L. in response to different environmental conditions was assessed. CPs occur highly dynamically. They do not contain thylakoids and their physiological function is still largely unknown. Controlled in situ sampling showed that CP formation follows a pronounced diurnal rhythm. Between 2 and 27 °C the relative proportion of chloroplasts with CPs (rCP) showed a significant positive correlation to leaf temperature (TL; 0.793, P < 0.01), while irradiation intensity had a minor effect on rCP. In situ shading and controlled laboratory experiments confirmed the significant influence of TL. Under moderate irradiation intensity, an increase of TL up to 25 °C significantly promoted CP formation, while a further increase to 37 °C led to a decrease. Furthermore, rCP values were lower in darkness and under high irradiation intensity. Gas treatment at 2000 ppm CO2/2% O2 led to a significant decrease of rCP, suggesting a possible involvement of photorespiration in CP formation. Our findings demonstrate that in R. glacialis, CPs are neither a rare phenomenon nor a result of heat or light stress; on the contrary, they seem to be most abundant under moderate temperature and non‐stress irradiation conditions. 相似文献