Search results for "ORL"
showing 10 items of 1863 documents
A model for planktic foraminiferal shell growth
1993
In this paper we analyze the laws of growth that control planktic foraminiferal shell morphology. We assume that isometry is the key toward the understanding of their ontogeny. Hence, our null hypothesis is that these organisms construct isometric shells. To test this hypothesis, geometric models of their shells have been generated with a personal computer. It is demonstrated that early chambers in log-spirally coiled structures cannot follow a strict isometric arrangement. In the real world, the centers of juvenile chambers deviate from the logarithmic growth curve. Juvenile stages are generally more planispiral and contain more chambers per whorl than adult stages. These traits are shown …
A revision of the new world species of Gymnoclasiopa Hendel (Diptera, Ephydridae)
2012
Species of the shore-fly genus Gymnoclasiopa Hendel from the New World are revised, including G. grecorum, sp. n. (Alaska. Juneau: Gastineau Channel, Thane Road (S Juneau; 58°16.9’N, 134°22.4’W)) and G. matanuska, sp. n. (Alaska. Matanuska-Susitna: Palmer (Matanuska River; 61°36.5’N, 149°04.1’W)). We also clarify the status of previously described species, including those now discovered to have Holarctic distributions and/or for which sexual dimorphism was not appreciated and the species was described twice, including G. montana (Cresson) as a syn. n. of G. bohemanni (Becker). Two species, G. bella (Mathis), comb. n., and G. chiapas (Mathis), comb. n., are transferred from Ditrichophora to …
Staying cool: preadaptation to temperate climates required for colonising tropical alpine-like environments.
2018
Plant species tend to retain their ancestral ecology, responding to temporal, geographic and climatic changes by tracking suitable habitats rather than adapting to novel conditions. Nevertheless, transitions into different environments or biomes still seem to be common. Especially intriguing are the tropical alpine-like areas found on only the highest mountainous regions surrounded by tropical environments. Tropical mountains are hotspots of biodiversity, often with striking degrees of endemism at higher elevations. On these mountains, steep environmental gradients and high habitat heterogeneity within small spaces coincide with astounding species diversity of great conservation value. The …
Do mosses really exhibit so large distribution ranges? Insights from the integrative taxonomic study of the Lewinskya affinis complex (Orthotrichacea…
2019
The strikingly lower number of bryophyte species, and in particular of endemic species, and their larger distribution ranges in comparison with angiosperms, have traditionally been interpreted in terms of their low diversification rates associated with a high long-distance dispersal capacity. This hypothesis is tested here with Lewinskya affinis (≡ Orthotrichum affine), a moss species widely spread across Europe, North and East Africa, southwestern Asia, and western North America. We tested competing taxonomic hypotheses derived from separate and combined analyses of multilocus sequence data, morphological characters, and geographical distributions. The best hypothesis, selected by a Bayes …
Multiple shifts to open habitats in Melastomateae (Melastomataceae) congruent with the increase of African Neogene climatic aridity
2018
International audience; AimAfrican Melastomateae (Melastomataceae) comprise c. 185 species occurring in closed or open habitats throughout sub-Saharan Africa. We sought to reconstruct biogeographical and habitat history, and shifts in diversification rates of African Melastomateae using a well-sampled, dated molecular phylogeny.LocationAmericas, sub-Saharan Africa, Madagascar, SE Asia.TaxonAngiosperms, Melastomataceae, African Melastomateae.MethodsPhylogenetic relationships were estimated based on an extensive sampling of New and Old World Melastomateae, using two nuclear and three plastid markers. Divergence times were estimated in BEAST based on three calibration priors under Bayesian unc…
Ancient DNA evidence for the loss of a highly divergent brown bear clade during historical times
2008
The genetic diversity of present-day brown bears (Ursus arctos) has been extensively studied over the years and appears to be geographically structured into five main clades. The question of the past diversity of the species has been recently addressed by ancient DNA studies that concluded to a relative genetic stability over the last 35,000 years. However, the post-last glacial maximum genetic diversity of the species still remains poorly documented, notably in the Old World. Here, we analyse Atlas brown bears, which became extinct during the Holocene period. A divergent brown bear mitochondrial DNA lineage not present in any of the previously studied modern or ancient bear samples was unc…
Lack of molluscan host diversity and the transmission of an emerging parasitic disease in Bolivia.
2001
Fasciolosis is a re-emerging parasitic disease that affects an increasing number of people in developing countries. The most severe endemic affects the Bolivian Altiplano, where the liver fluke (Fasciola hepatica) and its hermaphroditic snail host, Lymnaea truncatula, have been introduced from Europe. To achieve a better understanding of the epidemiological situation and the consequences of the colonization event of this invasive species, genetic analysis of Bolivian snail populations was needed. Here we compare the genetic diversity and population structure of snail samples from the Bolivian Altiplano with samples from the Old World at six polymorphic microsatellite loci. Whereas some vari…
New national and regional bryophyte records, 61
2019
New record of phytogeographical interest, at national or regional scale, for 47 bryophytes taxa are reported. New sites are located in 23 different geographical areas of . In particular, for each taxon, data on taxonomy, ecological as well as phytogeographical features are specified
Studies on the genusCapparisL. (Capparaceae) in Lao PDR
2016
Southeastern Asia is one of the main centres of diversity of the genus Capparis in the Old World. Morpho-chorological investigations carried out on collections from Lao PDR provided new data on the variation and distribution of some intrageneric taxa that were critical, poorly known or unrecorded in the country. The variability of Capparis pyrifolia and Capparis zeylanica is discussed, while Capparis acutifolia subsp. acutifolia and Capparis tenera are respectively confirmed and first recorded in Lao PDR. A new variety of Capparis micracantha is described and 12 lectotypes are designated. For each taxon morphological, chorological and autecological data are given.
Searching for solutions to the conflict over Europe’s oldest forest
2019
The Białowieża Forest World Heritage site is one of the last remaining primeval forests in lowland Europe and is a refuge for European Bison (Bison bonasus), the largest land mammal on the continent (Table 1).