Recent researches suggest that functional diversity represents the response of communities to environmental alterations better than taxonomic diversity. However, there is scarce information about how the functional diversity of freshwater fishes is affected by habitat type and the dominance of non-native species. To address this question, we analysed a large database containing 15 morpho-functional traits of 61 fish species from the Pannon Biogeographic region (Hungary). Based on a fish faunistic list and relative abundance of taxa, we quantified the taxonomic and functional diversity of riverine communities for > 700 sites of six habitat types. We asked how non-native fishes affected the taxonomic and functional diversity in different river types and at the local scale (i.e. at the site level), and how the diversity measures of native fauna elements changes along the invasion gradient. Our results showed that both functional and taxonomic richness increases with habitat complexity, from small headwater streams to large rivers. Therefore taxonomic diversity served as a good proxy for functional diversity along the environmental gradient of river types. Non-natives showed considerable functional diversity relative to their species number in each habitat type. Diversity values of native fauna elements initially increased, and then showed a major decrease along the invasion gradient. River type-specific evaluations highlighted the importance of considering the proliferation of invasive species based on both taxonomic and functional diversity indices. We argue that type-specific action plans are needed in conservation management to preserve the taxonomic and functional diversity of native fishes in Hungary, but also elsewhere.
Several recent notes prove that taxonomic relations of close relative animal groups (species complexes or cryptic species) can be revealed by the combined use of genetic and morphologic methodologies. At the same time scarce information can be found about how phylogeny, population origin, and sexual dimorphism affect the morphometric features of these species. In our present work, we performed simultaneous phylogenetic and morphological studies on the taxonomically still questionable Carpathian stream dwelling gudgeons (Cyprinidae, Gobio) by using two different methodologies (distance based and geometric morphometry). Our results were in correspondence with the previous findings, showing the presence of three phylogenetically more or less distinct groups in the area. The results of the whole-body geometric and the traditional, distance-based morphometry reflected the extent of phylogenetic differences. While the results of geometric scale morphometry did not correspond with the genetic subdivisions. Results of three way PERMANOVA analyses showed that the phylogenetic effects on morphometry is less considerable as the population origin or the sexual dimorphism at these cyprinid taxa. Our investigation contributed to the better understanding of the taxonomy of fish stocks in the Carpathian Basin, and to their conservation, but additional investigations will be needed to clarify the exact taxonomic position of the gudgeons (’Gobio sp1’) dominating the eastern part of the studied drainage.
Distance-based morphometry is still widely used in ichthyology. Beside others, this methodology is often used to characterise species or to compare intraspecific group (i.e. population level) differences. However, scarce information is available about: (a) which are the most widely used variables for these purposes, (b) how certain variables are selected for the morphometric analyses, and (c) how variable set compositions and the number of variables affect the results. To answer these questions, a literature review was compiled and our own three datasets were analysed. The results showed that although a high number of variables can be used, previous authors have measured “common” ones most often, regardless of the taxonomic position of the studied group and the goal of the survey. Additionally, our review showed that authors rarely made a variable selection and often did not standardise their datasets; these are methodical problems that make the accuracy and usability of the results questionable. Analyses of our own three datasets showed that the number of variables and the variable set compositions in most cases strongly influenced stock subdivision and the percentage of correctly classified individuals. It was also shown that the most useable variable sets for morphometric purposes can differ considerably depending on the taxon and goal of the survey.
Background Pikes, members of genus Esox, are widespread freshwater predators of the northern hemisphere, and important sport fish also. From the Carpathian basin only one species, the northern pike (E. lucius) is noted. At the same time the pike stocks living in this area show high level of phenotypic variance (e.g. various body pattern) and its growth varies highly both among and within populations. These features usually explained by the environmental diversity of the area. Whereas we think that genetic reasons -e.g. the appearance of other/new pike species in the area- may also be responsible for these observed features. Since as no detailed information have been published from the pike populations of this area, so far; we conducted phylogenetic and morphological assay on 88 pike specimens, collected from 49 Middle Danubian sampling sites. Results Our phylogenetic surveys showed that the northern pike appear in the study area solely, but all the three of its major lineages (Northern, Circumpolar, Southern) were indicated. Only six specimens represent the Northern lineage, collected from the western part of the study area. The Circumpolar and Southern lineages were common in the Carpathian basin, but the Southern lineage showed higher levels of haplotype diversity than the Circumpolar clade. Which indicates that only the Southern lineage is native in the area, while the other two groups could have appeared in the Middle Danubian system either spontaneously or by human introduction. Moreover, the different clades appeared in the same populations, suggesting the opportunity of inter-lineage hybridisation. From the studied morphologicalal features, the number of scales on the lateral line and the head length showed significant differences among the lineages. At the same time the body pattern of the studied individuals seems to be rather influenced by the ontogenic changes than phylogeny. Conclusions The high phenotypic variability of Middle Danubian northern pike populations may be due that all of its three major clades appeared and came in secondary contact in the area. In the within watershed spread of the non-native lineages the human stocking/transfer may play a considerable role.
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