The impacts of urbanisation on the ecology and evolution of dragonflies and damselflies (Insecta: Odonata)

Urbanisation is one of the main drivers of ecosystem change. The impacts of urban land use on biodiversity have been investigated, but other aspects of ecology have been overlooked, as well as the effects of urban stressors. Understanding the effects of specific urban stressors is crucial in order to appropriately manage urban areas and conserve their biodiversity. Dragonflies and damselflies (the Odonata) are a suitable taxon for evaluating the impacts of urbanisation on both terrestrial and aquatic ecosystems. Here, using a combination of field and laboratory data, I study the ecological impacts of urban stressors on odonates. I found that the urban heat island has negligible impacts on the phenology of odonates compared to climate change. Moreover, noise disturbance reduces significantly the feeding rate of the damselfly Ischnura elegans, although anthropogenic noise has no significant impact. Regarding the impacts of polarised light pollution (PLP), the strength of polarotaxis increased significantly with age in laboratory-reared specimens, but there was no significant differentiation between urban and rural populations. However, field-caught urban specimens showed less preference to polarised light compared to rural populations, suggesting strong selective pressures are acting upon urban populations, but no adaptation has occurred. Flight-related traits showed no significant differentiation among urban and rural populations of I. elegans. Lastly, biodiversity patterns did not differ among urban and rural areas, although aquatic vegetation and presence of fish were the main drivers of community composition. These results show odonates can tolerate a wide range of urban stressors, notably I. elegans. However, PLP, fish, and absence of aquatic vegetation in urban ponds can have a negative impact on odonate biodiversity, which has important implications on conservation and management of urban areas. Urban ecosystems are complex, thus an integrative approach is necessary in order to understand in depth the impacts of urbanisation on biodiversity

Water quality is a poor predictor of recreational hotspots in England

Maintaining and improving water quality is key to the protection and restoration of aquatic ecosystems, which provide important benefits to society. In Europe, the Water Framework Directive (WFD) defines water quality based on a set of biological, hydro-morphological and chemical targets, and aims to reach good quality conditions in all river bodies by the year 2027. While recently it has been argued that achieving these goals will deliver and enhance ecosystem services, in particular recreational services, there is little empirical evidence demonstrating so. Here we test the hypothesis that good water quality is associated with increased utilization of recreational services, combining four surveys covering walking, boating, fishing and swimming visits, together with water quality data for all water bodies in eight River Basin Districts (RBDs) in England. We compared the percentage of visits in areas of good water quality to a set of null models accounting for population density, income, age distribution, travel distance, public access, and substitutability. We expect such association to be positive, at least for fishing (which relies on fish stocks) and swimming (with direct contact to water). We also test if these services have stronger association with water quality relative to boating and walking alongside rivers, canals or lakeshores. In only two of eight RBDs (Northumbria and Anglian) were both criteria met (positive association, strongest for fishing and swimming) when comparing to at least one of the null models. This conclusion is robust to variations in dataset size. Our study suggests that achieving the WFD water quality goals may not enhance recreational ecosystem services, and calls for further empirical research on the connection between water quality and ecosystem services

Environmental noise reduces predation rate in an aquatic invertebrate

Noise is one of a wide range of disturbances associated with human activities that have been shown to have detrimental impacts on a wide range of species, from montane regions to the deep marine environment. Noise may also have community-level impacts via predator–prey interactions, thus jeopardising the stability of trophic networks. However, the impact of noise on freshwater ecosystems is largely unknown. Even more so is the case of insects, despite their crucial role in trophic networks. Here, we study the impact of underwater noise on the predatory functional response of damselfly larvae. We compared the feeding rates of larvae under anthropogenic noise, natural noise, and silent conditions. Our results suggest that underwater noise (pooling the effects of anthropogenic noise and natural noise) decreases the feeding rate of damselflies significantly compared to relatively silent conditions. In particular, natural noise increased the handling time significantly compared to the silent treatment, thus reducing the feeding rate. Unexpectedly, feeding rates under anthropogenic noise were not reduced significantly compared to silent conditions. This study suggests that noise per se may not necessarily have negative impacts on trophic interactions. Instead, the impact of noise on feeding rates may be explained by the presence of nonlinearities in acoustic signals, which may be more abundant in natural compared to anthropogenic noise. We conclude by highlighting the importance of studying a diversity of types of acoustic pollution, and encourage further work regarding trophic interactions with insects using a functional response approach

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

First records of the Tokay Gecko, Gekko gecko (Linnaeus, 1758) (Squamata, Gekkonidae), in Mexico

We report the first records of the invasive Tokay Gecko, Gekko gecko (Linnaeus, 1758), in Mexico, based on the discovery of five specimens from Reynosa, Tamaulipas

Evaluating Potential Distribution and Niche Divergence among Populations of the World’s Largest Living Damselfly, <i>Megaloprepus caerulatus</i> (Drury, 1782)

Megaloprepus caerulatus is a Neotropical species with a highly specialised niche, found from Mexico to Bolivia, primarily in mature tropical forests lower than 1500 masl. It is also the damselfly with the largest wingspan in the world. Recent studies found strong genetic isolation among populations of M. caerulatus. Further studies found genetic and morphological divergence, but ecological divergence was not tested. Here, we test for ecological divergence by evaluating niche differences among populations of M. caerulatus in Los Tuxtlas (Mexico), Corcovado (Costa Rica), Barro Colorado (Panama), and La Selva (Costa Rica). We used Ecological Niche Modelling (ENM) to compare potential distribution ranges, and we estimated the breadth and overlap of the ecological niche using equivalence and similarity tests. The potential distributions estimated with ENM were heavily fragmented and we found no geographic overlap of potential distributions among populations. However, we found geographic correspondence between populations with a close phylogenetic relationship. Even though all similarity tests were non-significant, the results of the equivalence tests suggest niche divergence between Corcovado and the other three populations, but also between Barro Colorado (Panama) and La Selva. These results show evidence of strong ecological divergence in Corcovado and Barro Colorado populations

Data obtained from individual River Basin Management Plans (Environment Agency, 2015) and Land Cover Map of Great Britain 2007 [31].

<p>See inset in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166950#pone.0166950.g002" target="_blank">Fig 2</a> for location of River Basic Districts.</p

Association of good/high overall water status and use of cultural ecosystem services for the eight River Basin Districts.

<p>The Odds Ratio (<i>OR</i>) of each River Basin District measures the likelihood that actual visits take place in sites characterized by good/high overall water status compared to random locations selected under a null model accounting for demand and substitutability (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166950#pone.0166950.t002" target="_blank">Table 2</a>). <i>OR</i> exhibits a statistically significant positive (negative) association (i.e. visits in good/high overall water status sites are more (less) common than random; solid colours) if the 90% confidence interval is completely above (below) the line <i>OR</i> = 1. The robustness of the results is tested by comparing null models, including a null model without weighting. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166950#pone.0166950.g002" target="_blank">Fig 2</a> for River Basin Districts acronyms.</p

Schematic diagram of the different steps undertaken within the analysis.

<p>Multiple data sources were combined (+), compared relative to each other (/) and tested against defined criteria (?). Colors match respective Methods sections: (i) Recreation use data curation (green); (ii) Water status and geospatial data (blue); (iii) Null models (orange); (iv) Statistical analysis (purple).</p

Null models for the expected % of visits in good/high overall water status sites.

<p>Null models for the expected % of visits in good/high overall water status sites.</p