Search results for "Systematics"

Diet composition and seasonal feeding patterns of a freshwater ringed seal (Pusa hispida saimensis)

2014

The Saimaa ringed seal (Pusa hispida saimensis) is one of the few freshwater seal populations worldwide. The major conservation issue of this critically endangered population is bycatch mortality. We used digestive tract content and stable isotopes (d 13 Ca ndd 15 N) to estimate the diet and seasonal feeding patterns for gaining better understanding of the seals feeding habits and potential conservation implications. The diet was similar across age groups. Altogether 15 fish species were identified and the most important were smelt (Osmerus eperlanus), ruff (Gymnocephalus cernuus), perch (Perca fluviatilis), vendace (Coregonus albula )a nd cyprinids. The high d 15 N values suggested that th…

Ulota larrainii (Orthotrichoideae, Orthotrichaceae, Bryophyta) a new species from Chile, with comments on the worldwide diversification of the genus

2015

A new species of Ulota D. Mohr, U. larrainii, is described from the Aysén Region, southern Chile. The characters that discriminate the new moss are the prostrate habit, leaves not crisped, marginal cells of the leaf base differentiated in 1(2) rows, vaginula hairy, exostome of 8 pairs of orange, recurved teeth, endostome of 16 broad and hyaline segments, and large, multicellular spores. The new moss is illustrated and compared with similar taxa. In addition, the presence of multicellular spores in the genus Ulota is summarized and evaluated from an updated list of currently accepted species. Finally, the distribution, species richness and levels of endemism in the different regions where Ul…

The stability of genetic variance?covariance matrix in the presence of selection

2007

Quantitative genetics provides one of the most important frameworks in which evolutionary biology and evolution can be studied. The primary goals of this field of study include the attempts to understand the history of selection that has resulted in the multiple phenotypic traits we observe today, and to predict the future trajectory of the multiple traits. Within quantitative genetics it is the genetic variance–covariance matrix G which summarizes the additive genetic variation of multiple traits and the genetic covariances between the traits, together with selection that control the direction and rate of evolution. The product of these two elements determine the response to selection from…

Biochemistry and genetics of insect resistance to Bacillus thuringiensis.

2001

▪ Abstract  Bacillus thuringiensis (Bt) is a valuable source of insecticidal proteins for use in conventional sprayable formulations and in transgenic crops, and it is the most promising alternative to synthetic insecticides. However, evolution of resistance in insect populations is a serious threat to this technology. So far, only one insect species has evolved significant levels of resistance in the field, but laboratory selection experiments have shown the high potential of other species to evolve resistance against Bt. We have reviewed the current knowledge on the biochemical mechanisms and genetics of resistance to Bt products and insecticidal crystal proteins. The understanding of th…

Pflanzenfamilien

1841

Fine Structure of the Tunic ofCiona intestinalisL. II. Tunic morphology, cell distribution and their functional importance

1981

Ciona intestinalis L. tunic architecture and cell distribution were investigated with the electron microscope. The observations showed that the ascidian covering is formed by a thin outer cuticle, a subcuticle of variable width and a large single layer of ground substance. “Large granule”, morula, phagocyte and granulocyte are the cellular types encountered; they appear mainly in highly vacuolated states and are distributed throughout the whole tunic. The “large granule” cells, however, are mainly seen in the cuticle layer and the morula cells appear mostly in the outer zone of the ground substance. The role of these cells in tunic construction, repair and regeneration as well as their scav…

�ber die statistische Berechnung der Streuung von Stoffwechselwerten

1951

Es wurden zwei grosere Serien von Ratten-Stoffwechselwerten hinsichtlich ihrer Annaherung an die Gausssche Normalverteilung bei verschiedenen Funktionen statistisch ausgewertet und gefunden, das die χ2-Werte — als Mas der Ubereinstimmung mit der Gauss-Kurve — nur bei Einfuhrung der Logarithmen unter dem fur signifikante Abweichungen geltenden Grenzwert bleiben. Die Berechnung der Streuung von Stoffwechselwerten mus daher mittels logarithmischer Werte, d. h. unsymmetrisch erfolgen.

Volatile constituents of Scutellaria rubicunda Hornem subsp. linnaeana (Caruel) Rech. (Lamiaceae) endemic in Sicily

2006

DOES ENVIRONMENTAL ROBUSTNESS PLAY A ROLE IN FLUCTUATING ENVIRONMENTS?

2013

Fluctuating environments are expected to select for individuals that have highest geometric fitness over the experienced environments. This leads to the prediction that genetically determined environmental robustness in fitness, and average fitness across environments should be positively genetically correlated to fitness in fluctuating environments. Because quantitative genetic experiments resolving these predictions are missing, we used a full-sib, half-sib breeding design to estimate genetic variance for egg-to-adult viability in Drosophila melanogaster exposed to two constant or fluctuating temperatures that were above the species' optimum temperature, during development. Viability in t…

Bet-hedging in diapausing egg hatching of temporary rotifer populations - A review of models and new insights

2014

Habitat unpredictability is a local adaptation factor shaping life-history traits in rotifer populations. It may select for the evolution of bet-hedging through risk-spreading strategies in diapausing egg hatching. This means that a fraction of diapausing eggs in wild populations do not hatch even when the conditions are favorable for population growth. Thus, there is a remaining fraction of viable diapausing eggs standing in the sediments for longer periods. According to theory, it is expected that the incidence of bet-hedging strategies for diapausing egg hatching will be higher in more uncertain habitats. Here, we review the major predictions derived from theoretical models applied to th…