Search results for " evolution."
showing 10 items of 9653 documents
Standardization proposal for the mapping of Caulerpa taxifolia expansion in the Mediterranean sea
1999
Fourteen years after the first observation of Caulerpa taxifolia (Valh) C. Agardh in the northwestern Mediterranean Sea, this green alga of tropical origin is now present in five countries (Spain, France, Monaco, Italy and Croatia). By the end of 1997, more than 46 km(2), at depths of between 0 and 50 m, were found to be affected by this expansion. A standardization of the cartographic procedure is proposed here. Such a standardization is necessary to compare maps produced by various organizations from different countries. For a given independent station, it is based on the definition of three levels of colonization:Level I refers to a station where one or several colonies less than 100 m a…
The Impact of Variations in the Climate on Seasonal Dynamics of Phytoplankton
2009
Phytoplankton, an assemblage of suspended, primarily autotrophic single cells and colonies, forms part of the base of the pelagic food chain in lakes. The responses of phytoplankton to anthropogenic pressures frequently provide the most visible indication of a long-term change in water quality. Several attributes related to the growth and composition of phytoplankton, such as their community structure, abundance as well as the frequency and the intensity of blooms, are included as indicators of water quality in the Water Framework Directive. The growth and seasonal succession of phytoplankton is regulated by a variety of external as well as internal factors (Reynolds et al., 1993; Reynolds,…
Larger cell or colony size in winter, smaller in summer – a pattern shared by many species of Lake Kinneret phytoplankton
2017
We examined an 8.5-year record (2004-2012) of cell size data for phytoplankton species from Lake Kinneret, Israel, sampled weekly or at 2-week intervals and determined microscopically by the same person. Many of the species abundant enough to be counted year-round showed a typical seasonal cell size pattern that repeated annually: cell diameter was maximal in winter and minimal in summer. This pattern was shared by species from different taxonomic groups including cyanobacteria, chlorophyta, and dinoflagellates. Similarly, in colonial species of diatoms, chlorophyta, and cyanobacteria the number of cells per colony was larger in winter and smaller in summer. We postulated that the seasonal …
Revision of the Afrotropical genus Leiodontocercus (Orthoptera, Tettigoniidae, Phaneropterinae) with a description of four new species
2020
Specimens belonging to the genus Leiodontocercus are rare or even absent in natural history museum collections; this is likely due to at least two reasons, notably, their relatively small size, and, the sheer difficulty in finding them in dense Afrotropical forests. Until recently, three species from less than fifteen specimens were known from this genus, whose identification relied on a singular diagnostic character, that is, the shape of the male cerci. The present contribution is based on the examination of thirty specimens collected from various countries, ranging from central to west Africa; apart from the male cerci, a second diagnostic character – the stridulatory file – is used to d…
Different responses of coexisting Chara species to foreseeable Mediterranean temperature and salinity increases
2017
Abstract An increase in temperature of approximately 4 °C is expected to occur in the Mediterranean by the end of the century. Concomitant to this warming, a foreseeable rise in salinity will affect aquatic species. We addressed the effects of warming and salinity, and their interaction on three coexisting characean species (Chara aspera, C. hispida and C. vulgaris) from a Spanish Mediterranean interdunal pond (spring water temperature 20–23 °C, when charophytes re-grew; salinity 1.3–1.8 PSU). A laboratory experiment was designed with two levels of water temperature treatment (23 and 27 °C), plus two levels of salinity treatment (0.4 and 4.0 PSU). The variables considered were total length,…
EST based phylogenomics of Syndermata questions monophyly of Eurotatoria
2008
Abstract Background The metazoan taxon Syndermata comprising Rotifera (in the classical sense of Monogononta+Bdelloidea+Seisonidea) and Acanthocephala has raised several hypotheses connected to the phylogeny of these animal groups and the included subtaxa. While the monophyletic origin of Syndermata and Acanthocephala is well established based on morphological and molecular data, the phylogenetic position of Syndermata within Spiralia, the monophyletic origin of Monogononta, Bdelloidea, and Seisonidea and the acanthocephalan sister group are still a matter of debate. The comparison of the alternative hypotheses suggests that testing the phylogenetic validity of Eurotatoria (Monogononta+Bdel…
Palaearctic species of Charipinae (Hymenoptera, Figitidae): two new species, synthesis and identification key
2018
The Charipinae Dalla Torre & Kieffer, 1910 present in the Palaearctic region are revised; 2410 specimens have been identified, belonging to 75 species: 52 to Alloxysta, one to Apocharips, six to Dilyta and 16 to Phaenoglyphis. For 33 species, new country-level distribution records are provided. Two new species are here described: Alloxysta palearctica Ferrer-Suay & Pujade-Villar sp. nov. and Alloxysta pascuali Ferrer-Suay sp. nov. A diagnosis for these species is included and their diagnostic features are shown in different figures. A key to identify all the species of Charipinae in the Palaearctic region is also given.
Charipinae (Hymenoptera: Cynipoidea: Figitidae) present in the Museum of Natural History of the University of Wroclaw, with an identification key for…
2020
Charipinae (Cynipoidea: Figitidae) deposited in the Museum of Natural History of Wroclaw University (Poland) have been studied. Seven species are recorded for the first time from Poland: Alloxysta brachyptera (Hartig, 1840), A. castanea (Hartig, 1841), A. citripes (Thomson, 1862), A. consobrina (Zetterstedt, 1838), A. mullensis (Cameron, 1883), A. nottoni Ferrer-Suay & Pujade-Villar, 2015 and Phaenoglyphis heterocera (Hartig, 1841). The presence of previously recorded species is confirmed and new records are specified. A key to all Charipinae species ever recorded in Poland is given.
New Charipinae ( Hymenoptera : Cynipoidea : Figitidae ) records from China
2016
Abstract Charipinae material collected from different provinces of China has been studied. Twenty-one previously described species have been identified: Alloxysta arcuata, A. brevis , A. carinata , A. castanea , A. consobrina , A. fracticornis , A. leunisii , A. macrophadna , A. mullensis , A. obscurata , A. paretasmartinezi , A. pilipennis , A. pilosa , A. postica , A. sawoniewiczi , A. victrix , A. xanthopa , Dilyta subclavata , Phaenoglyphis chinensis , P. heterocera and P. villosa . All species, except for P. chinensis and P. villosa , are here recorded for the first time from China. Diagnosis, material studied and distribution are given for each species. Plates with the diagnostic morp…
Taxonomic remarks on Scilla anthericoides Poir. (Asparagaceae, Scilloideae), a neglected species from Algeria
2016
Scilla anthericoides is a neglected name traditionally considered as Urginea maritima var. anthericoides. Based on recent field observations of living plants completed by karyological analyses, we promote again this taxon at species rank, under the genus Charybdis. It differs from other species of Charybdis maritima aggregate by many characters of flowers, fruits, bulbs, leaves and by ploidy level. It is endemic to the regional hotspot Kabylias-Numidia-Kroumiria in north-eastern Algeria. It is a threatened species that has been assessed as vulnerable.