Search results for " evolution."
showing 10 items of 9653 documents
Redescription of Chiropturopoda nidiphila Wiśniewski & Hirschmann (Acari: Uropodina) from a woodpecker’s tree holes, including all development stages…
2021
All development stages of Chiropturopoda nidiphila Wiśniewski & Hirschmann, 1983 are described, which has previously been known only from the deutonymph stage. The species is closely associated with tree holes excavated by woodpeckers. Chiropturopoda nidiphila was redescribed and the genus diagnosis was completed. The description of the species morphology is based largely on scanning (SEM) electronograms. Diagnoses differentiating all of the known species of the genus Chiropturopoda are provided, including their developmental stages.
A new perspective on adolescent athletes’ transition into upper secondary school : A longitudinal mixed methods study protocol
2016
The challenge of combining elite sport and education into a dual career pathway remains to be a source of concern for many high-performance athletes. Previous research findings suggest that committed participation in both domains is highly demanding and success in one pursuit often comes at the expense of the other. There are emergent studies, however, that argue for the beneficial and complementary nature of dual career pathways. Consequently, we emphasize the importance of understanding the processes underlying differences in the development of athletes’ life trajectories. This article presents a study protocol to explore new methodological and analytical approaches that may extend curren…
Ecologists overestimate the importance of predictor variables in model averaging: a plea for cautious interpretations.
2014
Abstract: Information-theory procedures are powerful tools for multimodel inference and are now standard methods in ecology. When performing model averaging on a given set of models, the importance of a predictor variable is commonly estimated by summing the weights of models where the variable appears, the so-called sum of weights (SW). However, SWs have received little methodological attention and are frequently misinterpreted. We assessed the reliability of SW by performing model selection and averaging on simulated data sets including variables strongly and weakly correlated to the response variable and a variable unrelated to the response. Our aim was to investigate how useful SWs are …
Legacy system evolution - A comparative study of modernisation and replacement initiation factors
2007
Decisions regarding information system evolution strategy become topical as the organisation’s information systems age and start to approach the end of their life cycle. An interview study was conducted in order to compare factors influencing modernisation and replacement initiation. System age, obsolete technology and high operation or maintenance costs were identified as triggers for both modernisation and replacement projects. The results show that the most prevalent individual reason for modernisation initiative is business development. Common initiation factors for replacement projects were end of vendor support and system’s inability to respond to organisation’s business needs. peerRe…
Chromosomal dynamics in platyrrhinae by mapping bacs probes
2012
molecular cytogenetics, cloned DNA probe, new evolutionary centromere, human synteny 4, phylogeny
Variation in the Sizes of Chthamalid Barnacle Post-Settlement Cyprids on European Shores
2001
As part of a wider study on the settlement and recruitment of Chthamalus spp. in Europe, this study investigated whether chthamalid cyprids can be separated by length on a European scale. Variation in cyprid length with latitude and temporal variation at selected localities were also examined. The lengths of cyprids collected between 1996-1999 on nine rocky shores in Europe are reported. Elminius modestus cyprids were found only at Roscoff, NW France and could be distinguished due to their Carapace shape and length. They showed a unimodal length distribution, measuring between 450 and 625 mum, with no variation in length between the two sampling dates (1997 and 1998). Based on carapace shap…
A new species within the Centaurea busambarensis complex (Asteraceae, Cardueae) from Sicily
2022
The Centaurea busambarensis group is made up by eight species endemic to Sicily. We statistically evaluated a population found on the Nebrodi Mountain (NE Sicily) to verify if the observed morphological differences with the already known taxa justified the description of a new one. It resulted in being sufficiently distinct to deserve recognition at the species level. Centaurea valdemonensis, a new species endemic to Sicily is described and illustrated here. It is confined to the Nebrodi Mountains (NE Sicily). The distinction of this taxon from the others belonging to the C. busambarensis complex has been supported with the aid of statistical analyses on morphological characters. The differ…
No phylogeographic structure in the circumpolar snowy owl (Bubo scandiacus)
2008
The snowy owl (Bubo scandiacus) is a nomadic species with a circumpolar distribution. It has recently declined in the western Palearctic and may thus be worthy of special consideration for conservation. We investigated genetic structure in three well separated geographic regions within the snowy owls’ breeding range. We sequenced two mitochondrial genes; the control region and cytochrome b, and two Z-chromosome introns; VLDLR-9 and BRM-15. We found no phylogeographic structure among the sampled regions, indicating high levels of gene flow in the recent past and possibly still today. Intra-population diversity did not vary between regions for the control region, but for Cyt b, North American…
Phylogeography of a Palaearctic sedentary passerine, the willow tit (Parus montanus)
2001
We analysed variation of the mitochondrial control region from willow tits through its Palaearctic distribution range. Although we found high amount of genetic variation (π=1.114%), there was almost no differentiation between subspecies or geographical localities. This may be because of a combination of several ecological and genetic factors, including a relatively homogenic habitat through the distribution range, lack of geographical barriers, high gene flow and a large long-term effective population size. On the contrary, in the songar tit, which is sometimes considered to be conspecific with the willow tit, the mitochondrial lineages seem to correlate with the geographical locality and a…
Environmental features of deep-sea habitats linked to the genetic population structure of a crustacean species in the Mediterranean Sea
2009
The deep-sea habitat, from 200 to 2000 m depth, has long been thought as an ecosystem where biotic and abiotic factors vary very little and consequently species are not disturbed by processes and phenomena which could promote fast evolutionary mechanisms. Unfortunately, biological information relating to deep water is limited, especially regarding the population genetics of species inhabiting the Mediterranean Sea, and general patterns cannot be inferred. In this study we report data on the population genetic structure of Aristeus antennatus, a deep-sea decapod crustacean species which has been widely studied due to its important economic value. We surveyed and examined the variation in a 3…