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971.
Rolf F. Hoekstra 《Journal of theoretical biology》1980,87(4):785-793
This paper extends the population genetic model of (the evolution of) anisogamy of Charlesworth (1978), which is based on the model of Parker, Baker & Smith (1972). The effect of parthenogenesis on the evolution of anisogamy is examined; this effect turns out to be only quantitative. Furthermore, the problem of the occurrence of only two different gamete sizes is considered. It is shown that a stable polymorphism with three different gamete sizes cannot exist. This result is robust to changes in the mating structure (random or disassortative gamete fusion) and to changes in the mode of reproduction (only sexual or partially parthenogenetic). 相似文献
972.
Rolf W. Sparidans J. Jantien Kettenes-van den Bosch Olaf van Tellingen Bastiaan Nuyen Roland E. C. Henrar Jos M. Jimeno Glynn Faircloth Pablo Floriano Kenneth L. Rinehart Jos H. Beijnen 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,729(1-2)
A sensitive bio-analytical assay in plasma of the depsipeptide aplidine is reported, based on reversed-phase liquid chromatography and fluorescence detection of the trans-4′-hydrazino-2-stilbazole (4′H2S) derivative of the analyte. At ambient temperature, two conformations of the depsipeptide are observed in solution due to cis–trans isomerism at the proline–pyruvoyl peptide bond. Aplidine is isolated from the matrix by solid-phase extraction on an octadecyl modified silica stationary phase. After evaporation of the acetone eluate, a derivatization with 4′H2S is performed in a water–acetonitrile mixture at pH 4. The reaction mixture is injected directly into the chromatograph and the analyte is quantified by fluorescence detection at 410 and 560 nm for excitation and emission, respectively. The method has been validated in the 2–100 ng/ml-range, 2 ng/ml being the lower limit of quantification. Precision and accuracy both meet the current requirements for a bioanalytical assay. The identity of the 4′H2S reaction products of aplidine have been confirmed by mass spectrometric analysis. Finally, the method has been employed for a pilot pharmacokinetic study of aplidine in mice which demonstrated its usefulness for pharmacological research. 相似文献
973.
Rolf Georg Beutel Ignacio Ribera Martin Fikáček Alexandros Vasilikopoulos Bernhard Misof Michael Balke 《Systematic Entomology》2020,45(2):378-395
The evolution of the coleopteran suborder Adephaga is discussed based on a robust phylogenetic background. Analyses of morphological characters yield results nearly identical to recent molecular phylogenies, with the highly specialized Gyrinidae placed as sister to the remaining families, which form two large, reciprocally monophyletic subunits, the aquatic Haliplidae + Dytiscoidea (Meruidae, Noteridae, Aspidytidae, Amphizoidae, Hygrobiidae, Dytiscidae) on one hand, and the terrestrial Geadephaga (Trachypachidae + Carabidae) on the other. The ancestral habitat of Adephaga, either terrestrial or aquatic, remains ambiguous. The former option would imply two or three independent invasions of aquatic habitats, with very different structural adaptations in larvae of Gyrinidae, Haliplidae and Dytiscoidea. 相似文献
974.
Abdur Rahman B. Saghir Louis K. Mann Marion Ownbey Rolf Y. Berg 《American journal of botany》1966,53(5):477-484
The North American species of Allium exclusive of A. schoenoprasum and A. tricoccum of Old World affinity are grouped on the basis of morphological similarity into eight discontinuous species alliances typified by A. acuminatum, A. campanulatum, A. canadense, A. cernuum, A. falcifolium, A. kunthii, A. sanbornii, and A. validum, respectively. Representatives of each of these alliances were compared with respect to volatile constituents responsible for characteristic odors by means of gas chromatography. Results indicate that these volatiles provide evidence of relationship useful in the classification of alliums. Uniformity was found in composition of volatiles in the representatives of the A. canadense, A. cernuum, A. kunthii, and A. sanbornii alliances. Variation was observed in the A. acuminatum, A. campanulatum, and A. falcifolium alliances. A. validum was the only species of its alliance studied. Vapors of A. validum contain mostly n-propyl sulfides (onion-like odor) as does the cultivated A. cepa. Methyl sulfides (cabbage-like odor) predominate in the A. sanbornii alliance. A few species of the A. acuminatum and A. falcifolium alliances contain mainly allyl sulfides (garlic-like odor). 相似文献
975.
Montecinos A Broitman BR Faugeron S Haye PA Tellier F Guillemin ML 《BMC evolutionary biology》2012,12(1):97
ABSTRACT: BACKGROUND: The Chilean shoreline, a nearly strait line of coast expanding across 35 latitudinal degrees, represents an interesting region to assess historical processes using phylogeographic analyses. Stretching along the temperate section of the East Pacific margin, the region is characterized by intense geologic activity and has experienced drastic geomorphological transformations linked to eustatic and isostatic changes during the Quaternary. In this study, we used two molecular markers to evaluate the existence of phylogeographic discontinuities and detect the genetic footprints of Pleistocene glaciations among Patagonian populations of Mazzaella laminarioides, a low-dispersal benthic intertidal red seaweed that inhabits along ~3,700 km of the Chilean coastal rocky shore. RESULTS: Three main genetic lineages were found within M. laminarioides. They are distributed along the Chilean coast in strict parapatry. The deep divergence among lineages suggests that they could be considered putative genetic sibling species. Unexpectedly, genetic breaks were not strictly concordant with the biogeographic breaks described in the region. A Northern lineage was restricted to a broad transition zone located between 30degreesS and 33degreesS and showed signals of a recent bottleneck. The reduction of population size could be related to warm events linked to El Nino Southern Oscillation, which is known to cause massive seaweed mortality in this region. To the south, we propose that transient habitat discontinuities driven by episodic tectonic uplifting of the shoreline around the Arauco region (37degreesS-38degreesS); one of the most active forearc-basins in the South East Pacific; could be at the origin of the Central/South genetic break. The large beaches, located around 38degreesS, are likely to contribute to the lineages' integrity by limiting present gene flow. Finally, the Southern lineage, occupies an area affected by ice-cover during the last glaciations. Phylogeny suggested it is a derived clade and demographic analyses showed the lineage has a typical signature of postglacial recolonization from a northern glacial refugium area. CONCLUSIONS: Even if environmental adaptation could have strengthened divergence among lineages in M. laminarioides, low dispersal capacity and small population size are sufficient to generate phylogeographic discontinuities determined by genetic drift alone. Interestingly, our results confirm that seaweed population connectivity over large geographic scales does not rely only on dispersal capacity but also seem to depend highly on substratum availability and population density of the receiving locality. 相似文献
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