Local climate determines intra- and interspecific variation in sexual size dimorphism in mountain grasshopper communities

The climate is often evoked to explain broad-scale clines of body size, yet its involvement in the processes that generate size inequality in the two sexes (sexual size dimorphism) remains elusive. Here, we analyse climatic clines of sexual size dimorphism along a wide elevation gradient (i) among grasshopper species in a phylogenetically controlled scenario and (ii) within species differing in distribution and cold tolerance, to highlight patterns generated at different time scales, mainly evolutionary (among species or higher taxa) and ontogenetic or microevolutionary (within species). At the interspecific level, grasshoppers were slightly smaller and less dimorphic at high elevations. These clines were associated with gradients of precipitation and sun exposure, which are likely indicators of other factors that directly exert selective pressures, such as resource availability and conditions for effective thermoregulation. Within species, we found a positive effect of temperature and a negative effect of elevation on body size, especially on condition-dependent measures of body size (total body length rather than hind femur length) and in species inhabiting the highest elevations. In spite of a certain degree of species-specific variation, females tended to adjust their body size more often than males, suggesting that body size in females can evolve faster among species and can be more plastic or dependent on nutritional conditions within species living in adverse climates. Natural selection on female body size may therefore prevail over sexual selection on male body size in alpine environments, and abiotic factors may trigger consistent phenotypic patterns across taxonomic scales.Funding was partially provided by the Spanish Ministries of Science and Innovation (grants CGL2008-02749, CGL2009-11302 and CGL2011-28177) and Agriculture and Environment (grant 375/2011). J.C. Illera was supported by a Ramón y Cajal postdoctoral fellowship.Peer reviewe

Genetic characterization, distribution and prevalence of avian pox and avian malaria in the Berthelot's pipit (Anthus berthelotii) in Macaronesia

9 pages, 4 figures, 1 table, 1 appendix.-- PMID: 18762985 [PubMed].-- Printed version published Nov 2008.Exotic pathogens have been implicated in the decline and extinction of various native-island-bird species. Despite the fact that there is increasing concern about the introduction of diseases in island ecosystems, little is known about parasites in the islands of Macaronesia. We focus on Berthelot’s pipit (Anthus berthelotii), an endemic and widespread Macaronesian bird species, using a combination of field studies and molecular techniques to determine: (1) the range and prevalence of avian pox and malaria in Berthelot’s pipits throughout the species’ distribution, (2) the genetic characterization of both parasites in order to ascertain the level of host specificity. We sampled 447 pipits across the 12 islands inhabited by this species. Overall, 8% of all individuals showed evidence of pox lesions and 16% were infected with avian malaria, respectively. We observed marked differences in the prevalence of parasites among islands both within and between archipelagos. Avian pox prevalence varied between 0–54% within and between archipelagos and avian malaria prevalence varied between 0–64% within and between archipelagos. The diversity of pathogens detected was low: only two genetic lineages of avian malaria and one lineage of avian pox were found to infect the pipit throughout its range. Interestingly, both avian malaria parasites found were Plasmodium spp. that had not been previously reported in the Macaronesian avifauna (but that had been observed in the lesser kestrel Falco naumannii), while the avian pox was a host specific lineage that had previously been reported on two of the Canary Islands.This work was supported by a postdoctoral fellowship from the Spanish Ministry of Education and Science (Ref.: EX2005-0585), by a grant from John and Pamela Salter Charitable Trust to JCI, and by a UK NERC fellowship to DSR. The Regional Government of the Canary Islands and Regional Government of Madeira gave permission to trap and ring birds. The Spanish Ministry of Environment gave permission to work in the National Park of Las Cañadas del Teide. The Cabildo of Fuerteventura provided accommodation in the Fuerteventura Island. Thanks also to the staff of the Natural Park of Madeira for providing logistical support in the Madeiran and Selvagen archipelagos and to the Portuguese Navy for transport to Selvagem Grande and Deserta Grande

Phylogenetic relationships, biogeography and speciation in the avian genus Saxicola

The avian genus Saxicola is distributed throughout Africa, Asia, Europe and various islands across Oceania. Despite the fact that the group has great potential as a model to test evolutionary hypotheses due to the extensive variability in life history patterns recorded between and within species, the phylogenetic relationships among species and subspecies of this genus are poorly understood. We undertook a systematic investigation of the relationships within this genus with three main objectives in mind, (1) to test the monophyly of the genus; (2) to ascertain geographical origin and dispersal sequence; and (3) to test for monophyly within the most morphologically diverse species, S. torquata and S. caprata. We studied sequence data from the mitochondrial cytochrome b gene from 11 of the 12 recognized species and 15 of the 45 described subspecies. Four clades, two exclusively Asian, one Eurasian, and the fourth encompassing Eurasia and Africa, were identified. Based on our analyses, monophyly of the genus Saxicola is not supported and an Asian origin for the genus can be inferred. Results from DIVA analyses, tree topology and nodal age estimates suggest independent colonisation events from Asia to Africa and from Asia to the Western Palearctic, with the Sahara desert acting as a natural barrier for S. torquata. Subspecies and populations of S. torquata are not monophyletic due to S. tectes, S. dacotiae and S. leucura grouping within this complex. Subspecies and populations of S. caprata are monophyletic. Importantly, within S. torquata and S. caprata, slight morphological traits and plumage colour pattern differences used to recognize subspecies are indicative of the greater cryptic diversification that has occurred within this genus