Taxa

The formal definition of species as explanatory hypotheses presented by Fitzhugh (Marine Biol 26:155–165, 2005a, b) is emended. A species is an explanatory account of the occurrences of the same character(s) among gonochoristic or cross-fertilizing hermaphroditic individuals by way of character origin and subsequent fixation during tokogeny. In addition to species, biological systematics also employs hypotheses that are ontogenetic, tokogenetic,

Patches of riparian woody vegetation potentially help mitigate environmental impacts of agriculture and safeguard biodiversity. We investigated the effects of riparian forest on invertebrate diversity in coupled stream-riparian networks using a case study in the Zwalm river basin (Flanders, Belgium). Agriculture is one of the main pressures in the basin and riparian forest is limited to a number of isolated patches. Our 32 study sites comprised nine unshaded "unbuffered" sites which were paired with nine shaded "buffered" sites on the same stream reach, along with five 'least-disturbed' sites and nine downstream sites. We sampled water chemistry, habitat characteristics and stream and riparian invertebrates (carabid beetles and spiders) at each site. Three methods were used to quantify riparian attributes at different spatial scales: a visually-assessed qualitative index, quantitative estimates of habitat categories in six rectangular plots (10 × 5 m) and geographic information system (GIS)-derived land cover data. We investigated relationships between invertebrates and riparian attributes at different scales with linear regression and redundancy analyses. Spiders and carabids were most associated with local riparian attributes. In contrast, aquatic macroinvertebrates were strongly influenced by the extent of riparian vegetation in a riparian band upstream (100-300 m). These findings demonstrate the value of quantifying GIS-based metrics of riparian cover over larger spatial scales into assessments of the efficacy of riparian management as a complement to more detailed local scale riparian assessments in situ. Our findings highlight the value of even small patches of riparian vegetation in an otherwise extensively disturbed landscape in supporting biodiversity of both terrestrial and freshwater invertebrates and emphasize the need to consider multiple spatial scales in riparian management strategies which aim to mitigate human impacts on biodiversity in stream-riparian networks.

Abstract. Linnaeus and other 18th Century naturalists practiced nomenclature in a way that associated tax-on names more strongly with taxa (groups) than with the categorical ranks of the taxonomic (“Linnaean”) hierarchy. For those early naturalists, ranks functioned merely as devices for indicating hierarchical posi-tion that did not affect the application or spelling of taxon names. Consequently, taxa did not change their names simply because of changes in rank. For example, the name Reptilia did not change when the rank of the taxon designated by that name was changed from order to class. During the 19th Century, an alternative approach to nomenclature emerged that made rank assignment fundamental to the application and spelling of taxon names. Under this rank-based approach, which forms the basis of the current Zoological Code, names are implicitly defined in terms of ranks. As a consequence, names are more strongly associated with ranks than with taxa and thus taxa change their ...

Neste trabalho estudamos a dinâmica assintótica não linear de algumas equações parabólicas do tipo reação-difusão sob perturbações nos parâmetros e perturbações singulares no domínio do tipo dumbbell. Mais precisamente, trataremos dos atratores ...

Hosta is a widely grown ornamental plants and sometimes used as vegetables. Hybridization of hostas is frequently done by home gardener. We conducted an experiment using twelve hosta taxa (coded from T1-T12) to analyze the morphological traits based hierarchical cluster, euclidean distance and PCA with a view to provide necessary information to the hosta breeders. We used complete randomized design with five replicates for the data collection of morphological traits. H. sieboldiana and H. montana had similar morphological characters while H. longipes var. gracillima, H. kiyosumiensis were mostly similar morphological characters as well. From the dissimilarity analysis, it was found that the dissimilarity distance between H. alismifolia and H. montana was maximum (452.2) which was closely followed by H. longissima and H. montana (447.6) where as minimum dissimilarity distance between H. sieboldii and H. nakaiana (36.2). PCA indicated that two important components accounted for 97.76% of the total variation among traits in of hosta taxa. The first and second component contributed 81.92% and 15.84% of the total variation, respectively. Leaf area was found as a unique morphological trait. H. sieboldiana, H. montana and H. longipes var. gracillima shared the common components; as well as H. alismifolia with H. longissima, H. sieboldii with H. nakaiana and H. tardiva with H. longipes var. caduca comprised common components. Overall, results revealed importance morphological components in breeding ability in hosta taxa.

Patches of riparian woody vegetation potentially help mitigate environmental impacts of agriculture and safeguard biodiversity. We investigated the effects of riparian forest on invertebrate diversity in coupled stream-riparian networks using a case study in the Zwalm river basin (Flanders, Belgium). Agriculture is one of the main pressures in the basin and riparian forest is limited to a number of isolated patches. Our 32 study sites comprised nine unshaded “unbuffered” sites which were paired with nine shaded “buffered” sites on the same stream reach, along with five ‘least-disturbed’ sites and nine downstream sites. We sampled water chemistry, habitat characteristics and stream and riparian invertebrates (carabid beetles and spiders) at each site. Three methods were used to quantify riparian attributes at different spatial scales: a visually-assessed qualitative index, quantitative estimates of habitat categories in six rectangular plots (10 × 5 m) and geographic information syst...

Patches of riparian woody vegetation potentially help mitigate environmental impacts of agriculture and safeguard biodiversity. We investigated the effects of riparian forest on invertebrate diversity in coupled stream-riparian networks using a case study in the Zwalm river basin (Flanders, Belgium). Agriculture is one of the main pressures in the basin and riparian forest is limited to a number of isolated patches. Our 32 study sites comprised nine unshaded “unbuffered” sites which were paired with nine shaded “buffered” sites on the same stream reach, along with five ‘least-disturbed’ sites and nine downstream sites. We sampled water chemistry, habitat characteristics and stream and riparian invertebrates (carabid beetles and spiders) at each site. Three methods were used to quantify riparian attributes at different spatial scales: a visually-assessed qualitative index, quantitative estimates of habitat categories in six rectangular plots (10 × 5 m) and geographic information syst...