Relation between the habitat niche breadth and the geographic range size: A case study on palearctic voles (Mammalia: Rodentia: Arvicolinae)

Habitat niche breadth for Palearctic Arvicolinae species was estimated at both local (α- niche) and global (the entire geographic range, γ-niche) scales using occurrence records of species and environmental (climate, topography, and vegetation) data. Niche breadth was estimated in the space of the first two principal components of environmental variables using kernel smoothing of the densities of species occurrence points. The breadth of α-niches was estimated for a set of random points inside the geographic range in a series of buffers of increasing size around these points. Within each buffer, we calculated the overlap between the distribution of environment values for the kernel smoothed densities of species occurrence points and the distribution of environment values in the background environment. The α-niche breadth was calculated as the slope of the linear regression of the niche breadth for buffers of different size by the ln area of these buffers with a zero intercept. The γ-niche breadth was calculated as the overlap between the distributions of environmental values for the kernel smoothed densities of species occurrence points over the whole geographic range and the distribution of environmental values in the background environment and also approximated by linear regression of the species’ average α-niche to the geographic range area of this species. The results demonstrated that the geographic range size was significantly related with the α- and γ-niche breadth. The γ-niche breadth was significantly positively correlated with the α-niche breadth. Finally, the differences between the γ-niche breadth values that were directly estimated and extrapolated from the α-niche breadth (Δ) values were positively correlated with the geographic range size. Thus, we conclude that the species occupy larger geographic ranges because they have broader niches. Our estimations of the γ-niche breadth increase with the geographic range size not due to a parallel increase of the environmental diversity (spatial autocorrelation in the environment).

Waterlogging tolerance of the threatened grass Arthraxon hispidus and implications for its habitat niche within endangered wetlands in north-eastern New South Wales

Knowledge of a target species’ habitat niche and physiological tolerances is important for conservation planning. However, these factors are not well understood for the threatened annual grass Arthraxon hispidus in New South Wales (NSW). Although the species is widespread in modified environments, recent studies have suggested that several threatened wetland types may represent original native habitat for the species, but documented field examples are lacking and the species’ physiological response to soil moisture is not clear. We undertook a detailed survey of an A. hispidus population within a relatively intact native sedgeland community, and carried out a nursery experiment to test the hydrological tolerances of the species. We found that A. hispidus plants grew more vigorously in poorly drained or waterlogged conditions, suggesting that the species is well-adapted to overcome such stressors, possibly through the formation of adventitious roots, a trait shared by many wetland plants globally. Our field survey confirmed that the A. hispidus population within the study site occurred only within species assemblages that were characteristic of a freshwater wetland formation and that matched descriptions of a listed endangered ecological community. These findings provide a deeper insight into the species’ habitat and threats, and offer a valuable management focus for conservation of A. hispidus as a component of threatened wetland communities in north-eastern NSW.

Species associations and management intensity modulate the habitat niche breadth of forest birds

Species associations can have profound effects on the realized habitat niche of species, indicating that habitat structure alone cannot fully explain observed abundances. To account for this aspect of community organization in niche modelling, we developed multi-species abundance models, incorporating the local effect of potentially associated species, alongside with environmental ones, targeting mainly forest management intensity. We coupled it with a landscape-scale analysis to further examine the role of management intensity in modifying the habitat niche in connection with the landscape context. Using empirical data from the Black Forest in southern Germany, we focused on the forest bird assemblage and in particular on the cavity nester and canopy forager guilds. We included in the analysis species that co-occur and for which evidences suggest association is likely. Our findings show that the local effect of species associations can moderate the effects of management intensity. We also found that species express a larger habitat niche breadth in intensively managed forests, depending on the landscape context. Species associations may facilitate the utilization of a broader range of environmental conditions under intensive forest management, which benefits some species over others. Such network of associations may be a relevant factor in the effectiveness of conservation-oriented forest management.

Characterization of bacterial communities associated with the pinewood nematode insect vector Monochamus alternatus Hope and the host tree Pinus massoniana

Background: Monochamus alternatus Hope is one of the insect vectors of pinewood nematode (Bursaphelenchus xylophilus), which causes the destructive pine wilt disease. The microorganisms within the ecosystem, comprising plants, their environment, and insect vectors, form complex networks. This study presents a systematic analysis of the bacterial microbiota in the M. alternatus midgut and its habitat niche.Methods: Total DNA was extracted from 20 types of samples (with three replicates each) from M. alternatus and various tissues of healthy and infected P. massoniana (pines). 16S rDNA amplicon sequencing was conducted to determine the composition and diversity of the bacterial microbiota in each sample. Moreover, the relative abundances of bacteria in the midgut of M. alternatus larvae were verified by counting the colony-forming units.Results: Pinewood nematode infection increased the microbial diversity in pines. Bradyrhizobium, Burkholderia, Dyella, Mycobacterium, and Mucilaginibacter were the dominant bacterial genera in the soil and infected pines. These results indicate that the bacterial community in infected pines may be associated with the soil microbiota. Interestingly, the abundance of the genus Gryllotalpicola was highest in the bark of infected pines. The genus Cellulomonas was not found in the midgut of M. alternatus, but it peaked in the phloem of infected pines, followed by the phloem of heathy pines. Moreover, the genus Serratia was not only present in the habitat niche, but it was also enriched in the M. alternatus midgut. The colony-forming unit assays showed that the relative abundance of Serratia sp. peaked in the midgut of instar II larvae (81%).Conclusions: Overall, the results indicate that the bacterial microbiota in the soil and in infected pines are correlated. The Gryllotalpicola sp. and Cellulomonas sp. are potential microbial markers of pine wilt disease. Additionally, Serratia sp. could be an ideal agent for expressing insecticidal protein in the insect midgut by genetic engineering, which represents a new use of microbes to control M. alternatus.

Characterization of bacterial communities associated with the pinewood nematode insect vector Monochamus alternatus Hope and the host tree Pinus massoniana

Background Monochamus alternatus Hope is one of the insect vectors of pinewood nematode ( Bursaphelenchus xylophilus ), which causes the destructive pine wilt disease. The microorganisms within the ecosystem, comprising plants, their environment, and insect vectors, form complex networks. This study presents a systematic analysis of the bacterial microbiota in the M. alternatus midgut and its habitat niche. Methods Total DNA was extracted from 20 types of samples (with three replicates each) from M. alternatus and various tissues of healthy and infected P. massoniana (pines). 16S rDNA amplicon sequencing was conducted to determine the composition and diversity of the bacterial microbiota in each sample. Moreover, the relative abundances of bacteria in the midgut of M. alternatus larvae were verified by counting the colony-forming units. Results Pinewood nematode infection increased the microbial diversity in pines. Bradyrhizobium , Burkholderia , Dyella , Mycobacterium , and Mucilaginibacter were the dominant bacterial genera in the soil and infected pines. These results indicate that the bacterial community in infected pines may be associated with the soil microbiota. Interestingly, the abundance of the genus Gryllotalpicola was highest in the bark of infected pines. The genus Cellulomonas was not found in the midgut of M. alternatus , but it peaked in the phloem of infected pines, followed by the phloem of heathy pines. Moreover, the genus Serratia was not only present in the habitat niche, but it was also enriched in the M. alternatus midgut. The colony-forming unit assays showed that the relative abundance of Serratia sp. peaked in the midgut of instar II larvae (81%). Conclusions Overall, the results indicate that the bacterial microbiota in the soil and in infected pines are correlated. The Gryllotalpicola sp. and Cellulomonas sp. are potential microbial markers of pine wilt disease. Additionally, Serratia sp. could be an ideal agent for expressing insecticidal protein in the insect midgut by genetic engineering, which represents a new use of microbes to control M. alternatus .

Sympatric competitors have driven the evolution of temporal activity patterns in Cnemaspis geckos in Southeast Asia

It is often assumed that animals’ temporal activity patterns are highly conserved throughout evolution. While most geckos are nocturnal, the species in the Cnemaspis genus are mostly diurnal (only a few are nocturnal). This raises a question about the evolution of a diel niche in the Cnemaspis genus. Cnemaspis geckos are distributed across Southeast Asia and are often sympatric with Cyrtodactylus, another widespread gecko genus in the same area. Since both genera are mainly rocky habitat specialists, we hypothesize that Cyrtodactylus may influence the temporal activity pattern of Cnemaspis when they are sympatric through competition. By analyzing habitat data, diel activity, and the existence of sympatric Cyrtodactylus species across the phylogeny of the Cnemaspis genus, we found (1) strong phylogenetic signals in the habitat use trait but not in temporal activity, suggesting that the diel niche of this genus is more labile compared with habitat niche, and (2) a significant association with the temporal activity pattern of Cnemaspis and the sympatry between the two genera, with the former tending to be diurnal when they are sympatric. Originated from a diurnal common ancestor, the release from competition with Cyrtodactylus species might open an opportunity for some Cnemaspis species to shift to nocturnal niches.

Distribution of a residual population of the Dytiscid Graphoderus bilineatus (de Geer, 1774) in the Grande Cariçaie nature reserves, Switzerland

Currently, the distribution of diving beetles in Switzerland is poorly known making it difficult to determine conservation priorities for species with small and/or declining populations. In order to establish conservation priorities, in 2018, we surveyed diving beetles of the genusGraphoderusin the Grande Cariçaie reserves with special consideration for the Red ListedG.bilineatus. WhileG.bilineatusandG.cinereusshowed high habitat niche overlap, the distribution ofG.bilineatuswas limited to mainly one of the eight reserves. When comparing our results to available historical data, the habitat ofG.bilineatushas likely diminished during the last 40 years. Our study provides the first comprehensive documentation of the distribution ofGraphoderusspecies in the Grande Cariçaie. We further highlight the importance for improving the knowledge ofG.bilineatusdistribution in Switzerland to develop policy for conservation of this globally threatened species.

Social factors for coastal management: A short review and some insights

Integration of social-economic and environmental perspectives are important in making the goal of coastal management to be obtained within expectation. In this review paper, the social factor is focused upon in particular. This is due to the fact that human cannot escape from surrounding which becomes their habitat niche. From this review, the social factors are known as 1) human attitudes, 2) differences of social-cultural values, ethics and classes, 3) population growth, 4) stakeholder/citizen perceptions, 5) involvement of social/public community, 6) anthropogenic activities, and 7) the involvement of managers and governance. Most dominantly, anthropogenic activities involved aquaculture, fishing, shipping and port activities, sediment mining, salt extraction, and tourism. Keywords: Coastal management; Human activities; Social factors