The authors have declared that no competing interests exist.
Conceived and designed the experiments: SG DSF AM. Analyzed the data: SG CC DSF JAC. Wrote the paper: SG CC DSF JAC JV LB AJG AM.
Invasions of alien species are considered among the least reversible human impacts, with diversified effects on aquatic ecosystems. Since prevention is the most cost-effective way to avoid biodiversity loss and ecosystem problems, one challenge in ecological research is to understand the limits of the fundamental niche of the species in order to estimate how far invasive species could spread.
One of the most important human impacts on a wide range of ecosystems is the introduction of alien species (e.g.
The success of this corixid as an alien species has been mainly attributed to its capacity: i) to live in brackish and saline waters in both the juvenile and adult phases
Whether this corixid is causing loss of native aquatic invertebrate populations is still partially unclear and under study, but it is the dominant hemipteran in many of the invaded sites where it is found
Since prevention of invasions is the most cost-effective way to avoid biodiversity loss and nature conservation problems
This study aims to estimate the potential distribution of
This study represents the first attempt to estimate potential areas of invasion by
Different modelling methods may be arranged along the gradient of potential-realized distribution according to their ability to model any concept (potential distribution refers to the places where a species could live, while realized distribution refers to the places where a species actually lives; see Jiménez-Valverde et al.
When estimating species’ fundamental niches, single procedures are likely to misrepresent the true range of climatic variation that those species are able to tolerate
We used an established procedure which maximizes the capacity to represent geographically the potential distribution of a species based only on distributional data
Because species distribution models that do not incorporate global data could misrepresent potential distributions
Map of native (triangles) and invaded (circles) distribution areas of
Climatic data were obtained from WORLDCLIM, version 1.3 (
We used a multidimensional envelope procedure (MDE) to obtain a map with the potential distribution of
Then, the maximum and minimum scores (extreme values) for all these relevant climatic variables were calculated in all cells with observed presence of
The potential distribution of a species can be considered to be the regions in which the climatic conditions fall within its thermal limits. Data on upper thermal limits (UTL) and lower thermal limits (LTL) were used to define
These values were considered because they are the most reliable and repeatable measures of thermal limits in aquatic insects. Following the same procedure as above, suitable grid squares were considered as all those meeting two conditions: i) lower value of “maximum temperature of the warmest month” (MaxTWM) than UTL and higher value of “minimum temperature of the coldest month” (MinTCM) than LTL; i.e., the thermal values falling within the range designated as suitable by physiological experiments. In the same way, following the same procedure as above, a binary potential distribution map was derived from these physiological thermal limits (PDPH).
To be conservative, we combined the potential distribution maps showing the climatically inhabitable areas for
Map of worldwide potential distribution of
To obtain a continuous value of climatic suitability within the PDCR, we calculated Mahalanobis distances (a measure of multidimensional non-Euclidean distance, MD) from each cell to the mean of the hypervolume of the selected variables, with reference to the species presence records. This procedure has been widely used in spatial ecology (e.g.
Map of worldwide current potential distribution of
The extreme values found above (those obtained from both current distribution and physiology) were projected with respect to a future climate scenario, to estimate the potential dynamics of invasion risk areas through time (i.e., combining current (PDCR) and future (PDF) model outputs, see
This map shows the worldwide future potential distribution of
Isothermality (BIOCLIM3) and Temperature Annual Range (BIOCLIM7) were the most relevant climatic variables identified by ENFA, and therefore these variables were used in the MDE procedure. Isothermality is defined by the relationship between Mean Diurnal Range and Temperature Annual Range, and is a quantification of how large the day-to-night temperature oscillation is in comparison to the summer-to-winter oscillation (see
Under the CCM3 scenario, the future climatic suitability of
The potential distribution maps produced here represent the first attempt to estimate the global potential distribution of the alien boatman
Western Europe has been already highlighted as a recipient area sensitive to invertebrate biological invasions
Invasive species coupled with climate change represent two of the most pervasive aspects of global environmental change
Although insect species are extremely rare among aquatic invaders
Humans have historically facilitated the spread of aquatic invasive species through intentional stocking, infrastructure construction, releases from aquaria and trade routes
In this sense, several studies have considered two potential means of dispersal for
Furthermore according with the BWM Convention
Our results suggest that major maritime trade routes between commercial harbours, especially in the Atlantic (e.g., New York, Buenos Aires), as well as in Europe and Asia
Small-scale dispersal of species is mainly due to natural means such as passive transport by wind
Moreover, invasion of alien species is considered among the major threats to wetland ecosystems in a worldwide context, also under future global change
A negative impact on other invertebrates is also possible.
Strong efforts are required to survey carefully the aquatic ecosystems in areas that are suitable for
On the other hand, genetic studies are advisable to establish whether the populations in South Africa and New Caledonia, or Europe and Africa, have a common origin, and clarify whether there have been multiple introductions from the native range. Furthermore, genetic studies are also required to clarify the separation of
(DOC)
We would like to thank all members of the “Ecología Acuática” Research Group (UMU).