Research Symposium—Aberdeen

ABSTRACT

Background: Climate change may increase the risk of biological invasions. However, current knowledge of this interaction is limited.

Aims: We aimed to quantify (1) the effect of climate change on the potential distribution of invasive plant species in Spain, (2) the importance of the area of origin of such species and (3) the vulnerability of different biogeographic provinces to future changes in climatic suitability for invaders.

Methods: We applied six methods of species distribution modelling to assess the variation of climatically suitable areas for 40 alien plants. We developed a Potential Area Change Index and used it as the response variable in modelling for three future emissions scenarios and three global circulation models over three time periods. The area of origin and biogeographic province in Spain were also considered.

Results: We found a highly specific response for each plant species rather than a clear trend for the entire set of species. Predicted climate suitability increased over higher emission scenarios and longer projected time lags. Neotropical species showed the greatest potential climatic range expansion. We detected a strong interaction between the geographic origin of a species and the biogeographic province.

Conclusions: Special attention should be given to the areas where aridification of climate is projected and where introduced neotropical species are likely to expand their range. Future work should develop accurate species-specific approaches that allow the management invasive plant species.     

Modelling chorotypes of invasive vertebrates in mainland Spain

We investigated the existence of chorotypes – assemblages of species with similar geographical ranges – of invasive species in a host territory, and their potential use to advocate similar control or management strategies for species in the same chorotype. We analysed the distribution of 13 exotic terrestrial vertebrate species (six birds, six mammals, and one reptile) with well‐known distributions in mainland Spain. We used the presence/absence data on a grid of 10 km × 10 km UTM cells from the Atlases of terrestrial vertebrates of Spain. These data were aggregated to a grid of 50 km × 50 km UTM cells, because it entailed no loss of meaningful information and allowed dealing with a much lower number of cells. Using cluster analysis and a probabilistic assessment of the classification, we identified seven significant chorotypes: four multispecific and three monospecific. The compound chorotypes grouped together species that tended to share certain characteristics about their introduction, release cause, establishment, and spread. We modelled the chorotypes using a favourability function based on a generalized linear model and 31 variables related to spatial situation, topography, lithology, climatic stability, energy availability, water availability, disturbances, productivity, and human activity. Climatic factors affected the favourability for every chorotype, whereas human variables had a high influence in the distribution of three chorotypes involving eight species. On the basis of these variables, we identified favourable areas for all the chorotypes in mainland Spain. The favourability for a chorotype in an area may be a useful criterion for evaluating the local conservation concern due to the whole set of species. Favourable but unoccupied areas can be used to infer possible colonization areas for each chorotype. We recommend using chorotypes to optimize broad‐scale surveillance of invasive species.     

A Late Pleistocene (MIS3) ungulate mammal assemblage (Los Rincones,Zaragoza, Spain) in the Eurosiberian–Mediterranean boundary

The Late Pleistocene archaeo-palaeontological sites in the Iberian Peninsula are located mainly on the coasts. Here, we present for the first time a palaeoenvironmental proxy for Upper Pleistocene locality (Marine Isotope Stage 3 MIS3) that is in the interior peninsular, in the Moncayo massif (Zaragoza). This is actually the boundary between Mediterranean and Eurosiberian climatic regions. This study is based in the site ungulates: Capra pyrenaica, which is larger in size than the current and fossil Capra from the Mediterranean area of the Iberian Peninsula. The horses have a small size, which is similar to that of the horses from Fontainhas and Casares. Significantly lesser in the number of specimens are the roe deer, the southern chamois and the auroch. The study and comparison of the faunal assemblage of the locality of Los Rincones with other sites of the Iberian MIS3 show a cluster of sites in the southern Peninsular, though separated, due to the abundance of Capra pyrenaica. The association of Los Rincones is similar to the southern peninsular sites such as Nerja, Gorham Cave, Cova Beneito and Zafarraya. The ungulate assemblage of Los Rincones represents a landscape with temperate climate, presence of steppe and patches of forest, similar to the current landscape surrounding the cavity today.     

Biological control reduces herbivore’s host range

The enemy release hypothesis predicts that alien populations are more vigorous and grow faster in introduced areas than within their natural range due to lack of natural enemies. An extension of this theory would be that the lack of natural enemies on an herbivore species will indirectly increase the number of host plant species that it can infest. The eucalyptus gall wasp Ophelimus maskelli is a recent introduction to the Mediterranean basin. Its arrival was followed after about two years by its parasitoid, Closterocerus chamaeleon. We evaluated the range of hosts used by the gall wasp by surveying 50 Eucalyptus species, 37 Eucalyptus hybrids and 18 E. globulus half-sibling families, before and after the establishment of the parasitoid. We found a consistent reduction in the observed host range of the gall wasp after the establishment of the parasitoid with a reduction of 83% on Eucalyptus species, 84% on hybrids, and 94% on E. globulus half-siblings. Host range narrowed down from 18 to three closely-related host species, all in the section Exsertaria, series Exsertae, E. camaldulensis, E. tereticornis and E. rudis, which are probably the standard hosts of O. maskelli. In the remaining affected species the intensity of attack decreased significantly in all studied regions. These findings show that, besides the direct gains from classical biological control, there may be indirect benefits through a natural-enemy-induced reduction in the range of host plants used by herbivorous insect pests.     

Habitat use and movements of plains zebra (Equus burchelli) in response to predation danger from lions

Prey species must adapt their behavior to avoid predation. Asa key prey item for lions (Panthera leo), plains zebras (Equusburchelli) were expected to respond to immediate threats posedby lions in their area. In addition, zebras were predicted toexhibit behavior tuned to reduce the potential for encounterswith lions, by modifying their movement patterns in the timesof day and habitats of greatest lion danger. We studied a populationof approximately 600 plains zebra living in Ol Pejeta Conservancy,Kenya. We found that zebra abundance on or near a grasslandpatch was lower if lions had also been observed on that patchduring the same day. Predation danger was highest in grasslandhabitat during the night, when lions were more active. Zebrasightings and global positioning system radio collar data indicatedthat zebras also reduced their use of grassland at night, insteadusing more woodland habitat. Zebras moved faster and took sharperturns in grassland at night. It is hypothesized that these moreerratic movements assist zebras in avoiding detection or captureby lions.