Calling songs of the sibling species Cicada barbara and C. orni were studied in sympatric and allopatric populations on the Iberian Peninsula, where the distribution ranges of both species overlap. No difference was found in any acoustic property for the sympatric and allopatric populations of C. barbara studied and only one variable (minimum frequency) was significantly different between sympatric and allopatric populations of C. orni. No hybrids with intermediate songs were found and no character displacement in the calling song was detected. It is very likely that these species were already considerably differentiated when they met on the Iberian Peninsula. Particularly, premating (or even postmating) isolating mechanisms (according to Mayr's Biological Species Concept) or different specific-mate recognition systems (in the view of the Paterson's Recognition Concept of Species) were most likely already present, which prevented hybridization between this pair of species. It is assumed that the calling songs are the most important premating isolating mechanism corresponding to the specific-mate recognition systems of these species of cicadas.
In order to disentangle the contribution of host and parasite biology to host specificity, we compared the structure and population dynamics of the Gyrodactylus (von Nordmann, 1832) flatworm community living on sympatric three-spined Gasterosteus aculeatus L. and nine-spined Pungitius pungitius (L.) stickleback. Between April 2002 and March 2003, a small lowland creek was sampled monthly. Species identity of about 75% of the worms per host was determined with a genetic nuclear marker (ITS1). Each stickleback species hosted a characteristic gill- and fin-parasitic Gyrodactylus: G. arcuatus Bychowsky, 1933 and G. gasterostei Gläser, 1974 respectively infecting the three-spined stickleback, with G. rarus Wegener, 1910 and G. pungitii Malmberg, 1964 infecting the nine-spined stickleback. Host size and seasonal dynamics were strong determinants of parasite abundance. A strong interaction between host and parasite species determined infection levels and affected three levels of parasite organisation: community structure, population structure and topographical specialisation. Community and population structure were shaped by asymmetric cross-infections, resulting in a net transmission of the Gyrodactylus species typical of the nine-spined stickleback towards the three-spined stickleback. Host density was not a major determinant of parasite exchange. Aggregation and topographical specialisation of the Gyrodactylus species of the three-spined stickleback were more pronounced than that of the nine-spined stickleback.
Euparyphium albuferensis and Echinostoma friedi cercarial infectivity to four species of sympatric snails was examined under single- or multiple-choice laboratory conditions to show the level of parasite-snail host compatibility. Radix peregra, Lymnaea fuscus, Physella acuta and Gyraulus chinensis act as second intermediate hosts of both parasite species although different cercarial transmission success (CTS) was observed. In single-host experiments, R. peregra and P. acuta showed a high degree of compatibility with E. albuferensis, while only P. acuta in the case of E. friedi. In two-choice snail communities, a snail with high CTS increased the values of another with low compatibility, in both parasite species. In multiple-choice snail communities, high CTS of some hosts decreased, while low CTS of other hosts increased. The degree of parasite-host compatibility of each snail species could be determined by the presence of other snails in the community.
We studied habitat selection of the woodchat Lanius senator, red-backed Lanius collurio, and masked Lanius nubicus shrikes in NE Greece, where they occur sympatrically. During the breeding season the masked shrike is most distinct, but woodchat and red-backed shrikes highly overlap in their habitat use. Multivariate discriminant analysis revealed the best separating variables from a set of 13 vegetation variables measured around perch sites. For axis one the best separating variables were identified as the woodland character, and the shrub character for axis two. By the help of the multivariate discriminant analysis the habitat selection in these avian species can be separated with high probability (64%, 64%, and 86% for the woodchat, red-backed and masked shrikes, respectively).
Multimammate mice of the genus Mastomys are widespread in sub-Saharan Africa and occur in a wide range of open habitats. Representatives of this genus are the most common African rodents, the main vertebrate agricultural pests and vectors of human pathogens. In Ethiopia, the biogeographically most complex eastern African country, several species have been reported, but their distribution has never been described because of their cryptic morphology. Here we present genetically identified species from 377 Ethiopian Mastomys specimens and analyse their distributional patterns. The genus, represented by four species, inhabits most of the country, with the exception of the highest mountains and dry areas, such as the Afar triangle and the Somali region. For the first time we document M. kollmannspergeri from a single locality in the northernmost part of Ethiopia. Three previously recorded species are more widespread – M. erythroleucus was found at 32 localities, M. natalensis at 13 localities and the Ethiopian endemic species M. awashensis at 18 localities. and Phylogenetic analysis of mitochondrial cytochrome b gene sequences indicates that only one of the six phylogroups of M. natalensis and one of the four phylogroups of M. erythroleucus are represented in Ethiopia. Haplotype network analysis indicates two subclades of Ethiopian M. erythroleucus separated by the Ethiopian Rift Valley. Using presence records, we constructed distribution models for the species and analysed the level of overlap. The predicted distribution shows most overlap between M. awashensis and M. natalensis, which is in agreement with empirical data as both species were found in sympatry at four localities. A medium level of overlap was predicted between M. natalensis and M. erythroleucus and both species were found co-existing at two localities. This study not only presents the first detailed distribution of cryptic Mastomys species, but also clearly identifies multimammate mice as model taxa for future evolutionary studies (e.g. the evolution of coexistence or host-parasite interactions) and indicates the regions suitable for such studies.
Morphometric analyses are used to evaluate the taxonomic status of two sympatric variants of Gyrodactylus anisopharynx Popazoglo et Boeger, 2000 (forma ''large-pharynx'' and forma ''small-pharynx''). The parasites were collected from the Piraquara River and the Miringuava River, State of Paraná, Brazil, between February 2005 and May 2006. A total of 132 parasites were measured from two hosts, Corydoras ehrhardti Steindachner and Corydoras paleatus (Jenyns). Eleven morphological features of the haptoral sclerites and pharynx were measured and analysed by discriminant analysis and principal components analysis. The results indicate that the observed morphological variation cannot be associated to intraspecific variation or phenotypic plasticity (P < 0.0001). Consequently, the two variants previously allocated in G. anisopharynx represent two independent species. Since the holotype was defined as the variant ''large-pharynx'', Gyrodactylus corydori sp. n. is proposed to accommodate specimens previously reported as ''small-pharynx'' variant of G. anisopharynx. Morphometric analyses showed that the hook, the anchor, and the pharyngeal bulb are significantly distinct (P < 0.0001) between G. corydori sp. n. and G. anisopharynx (s.s.). The new species is characterized by having hooks with point moderately curved, robust convex heel, convex shelf, toe concave moderately pointed with depression; deep bar with two submedial, posterior projections; anchors with robust superficial root; superficial bar with two small anterolateral projections; and male copulatory organ armed with two rows of spinelets.
A total of 7210 unfed adult Ixodes persulcatus Schulze, 1930 and I. ricinus (L., 1758) ticks were collected from the vegetation by flagging in 35 study sites located in the zone of their sympatry (mainly in Leningrad region, Russia). Borrelia infection in ticks was estimated by the dark-field microscopic analysis of gut contents in standard vital preparations at a magnification of ×600. No correlation was revealed between the series of parameters characterising the abundance of each tick species (τ = -0.13) and between the series of these parameters and the prevalence of Borrelia in each vector. It is concluded that in the broad zone of I. persulcatus and I. ricinus sympatry, the presence and proportion of one vector in the ecosystem does not have any significant effect on the extensity of infection and on the epizootic and epidemic significance of the other vector. Each tick species has its independent (of the other species) and relatively original functional role in the focal ecosystem.