Anastacio P.M.,University of Évora |
Banha F.,University of Évora |
Capinha C.,CIBIO InBio |
Bernardo J.M.,University of Évora |
And 3 more authors.
Ecological Indicators | Year: 2015
Red swamp crayfish (Procambarus clarkii) and signal crayfish (Pacifastacus leniusculus) are two invasive freshwater species with a worldwide distribution. The objective of this work was to investigate how the two species move and use space in an area of recent coexistence. Simultaneously, we test the use of new tools and indices to describe their movement patterns. To accomplish this we performed a radio-tracking program within a river-type habitat during two different periods (September/October 2010 and June/July 2013). We used spatial analysis tools to map crayfish radio-location data with and without accounting for the curvature of the river. To assess the consistency of the direction of movement and of the distances traveled by crayfish, two indices were developed. To assess the habitat preferences of each species we applied Ivlev's Electivity Index and the Standardized Forage Ratio. Movement of P. clarkii and P. leniusculus differed. The average detected movement was 8.8 m day-1 for P. clarkii and 17.5 m day-1 for P. leniusculus. However, crayfish behavior ranged from almost complete immobility - sometimes during several days - to large movements, in half a day, up to a maximum of 255 m for P. clarkii and 461 m for P. leniusculus. The proportion of upstream or downstream movements was independent of the species and both species displayed no preference for either direction. The indices of consistency of movement showed a large interindividual variation. Species and period (2010 or 2013) affected the mean daily distance traveled, maximum observed distance from location of release and percentage of observations under vegetation cover. The Ivlev's Electivity Index and the Standardized Forage Ratio presented similar results. P. clarkii showed a preference for pool areas with riparian vegetation cover while P. leniusculus preferred riffle and pool areas with riparian vegetation cover. Our work provided new and valuable data for modeling the active dispersal of these two problematic invaders in a context of coexistence. © 2015 Elsevier Ltd. All rights reserved.
Casey L.M.,University of Sussex |
Rebelo H.,CIBIO InBIO |
Rebelo H.,University of Bristol |
Rotheray E.,University of Sussex |
Goulson D.,University of Sussex
Diversity and Distributions | Year: 2015
Aim: There is widespread concern over the current state of global pollinator populations; however, lack of monitoring means patterns of decline are not well characterized. We aimed to investigate the influence of habitat and climate specializations on bumblebee distribution trends over time using long-term species data. Location: Our study is based on data from the UK and Ireland, for which the most comprehensive set of bumblebee records exists. Previous analysis of the UK data highlighted severe range contractions for a number of species by the 1980s. Methods: We use the most current dataset to quantify the extent of range change over three time periods (pre-1960, 1960-80 and 1981-2012) and to investigate whether species are becoming more marginal, that is occupying areas with more extreme or specialized climatic conditions within the UK and Ireland. For species that have contracted or become more marginal, we predict their climatic specialization within the UK and Ireland using Maxent models, allowing us to associate records with climatic suitability values for each time period and to investigate whether or not species are contracting towards their climatic optimum. Results: We find that populations of most rare bumblebee species appear to have stabilized post-1980, while the more common species appear to have expanded in range. However, rare species tend to have become more marginal in the sites they occupy post-1980, some have contracted towards their predicted climatic optimum and some of which also retracted towards coastal areas. Main conclusions: Our results provide a mixed picture of the state of the UK and Ireland's bumblebee fauna, and must be interpreted with caution as changing patterns of recorder effort may distort real trends. They highlight the need for future monitoring of the abundance of pollinators on both a regional and global scale. © 2015 John Wiley & Sons Ltd.
Brito J.C.,CIIMAR – Interdisciplinary Center of Marine and Environmental |
Harris D.J.,CIBIO InBIO |
Harris D.J.,University of Porto |
Froufe E.,CIBIO InBIO |
And 3 more authors.
Amphibia Reptilia | Year: 2013
The genetic diversity within Ptyodactylus ragazzii was analysed for the first time across the Western part of its range. We have used two mitochondrial (12s rRNA and 16s rRNA) and one nuclear (Cmos) marker to compare results directly with other related Ptyodactylus species, P. oudrii and P. hasselquistii. Results show high levels of intraspecific variability, with at least three divergent mtDNA lineages that have different haplotypes for Cmos and that are geographically concordant. P. ragazzii from Mauritania is probably a distinct species and possibly other lineages too, such as those from the Aïr Mountains in Niger, although more nuclear markers are needed to confirm this. All analysed Ptyodactylus species appear to be cryptic species complexes containing multiple deeply divergent forms, highlighting the need for a careful reassessment of the taxonomy of the whole genus. © Koninklijke Brill NV, Leiden, 2013.