Host‐plant dependent wing phenotypic variation in the neotropical butterfly Heliconius erato

Most phytophagous insects feed on a single plant during development, and this may influence not only performance‐linked traits, but also more subtle morphological differences. Insect–plant interactions are thus valuable for studying environmental influences on phenotypes. By using geometric morphometrics, we investigated the variation in forewing size and shape in the butterfly Heliconius erato phyllis reared on six species of passion vines (Passiflora spp.). We detected wing shape sexual dimorphism, for which the adaptive significance deserves further investigation. There was size as well as wing shape variation among individuals fed on different hosts. These subtle differences in shape were interpreted as environmental effects on development, which should be under weak natural selection for these traits, and therefore not strongly canalized. This result reinforces the role of plasticity on host‐plant use, as well as the corresponding consequences on developmental variability among phytophagous insects. We propose that this variation can be an important factor in resource specialization and partner recognition, possibly triggering reproductive isolation and sympatric speciation in phytophagous insects. This interaction also shows itself as a good model for studying the role of environmental and interaction diversity in evolution. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 765–774.     

Effect of water availability on leaf water isotopic enrichment in beech seedlings shows limitations of current fractionation models

Current models of leaf water enrichment predict that the differences between isotopic enrichment of water at the site of evaporation (Δ_e) and mean lamina leaf water enrichment (Δ_L) depend on transpiration rates ( E ), modulated by the scaled effective length ( L ) of water isotope movement in the leaf. However, variations in leaf parameters in response to changing environmental conditions might cause changes in the water path and thus L . We measured the diel course of Δ_L for ¹⁸O and ²H in beech seedlings under well-watered and water-limited conditions. We applied evaporative enrichment models of increasing complexity to predict Δ_e and Δ_L, and estimated L from model fits. Water-limited plants showed moderate drought stress, with lower stomatal conductance, E and stem water potential than the control. Despite having double E , the divergence between Δ_e and Δ_L was lower in well-watered than in water-limited plants, and thus, L should have changed to counteract differences in E . Indeed, L was about threefold higher in water-limited plants, regardless of the models used. We conclude that L changes with plant water status far beyond the variations explained by water content and other measured variables, thus limiting the use of current evaporative models under changing environmental conditions.     

Haematozoa infections in a Great Tit Parus major population in Central Portugal: relationships with breeding effort and health

Blood parasites may act as modulators of their hosts' ecology, life histories and fitness. We studied the prevalence of Plasmodium sp., Haemoproteus sp. and Leucocytozoon sp. and their effects on morphological, biochemical and haematological variables and on breeding effort of Great Tits Parus major . Total prevalence (percentage of individuals infected by any parasite) ranged from 7.7% to 61.1%. There was an overall positive association in prevalence between the three haematozoan parasites. No effect of sex or age on infection status was observed. Negative impacts of infection on physiological condition depended largely on year and/or season and included effects on body condition index, plasma protein and haemoglobin index. There were also indications that parasite infection increased immune response and stress levels and activated antioxidant defence mechanisms. Males with higher fledging success had a higher probability of Haemoproteus infection, and females laying heavier eggs had a higher probability of Plasmodium infection. However, clutch size was negatively associated with the probability of infection by Leucocytozoon and Haemoproteus . Surprisingly, males raising second broods had a lower prevalence of both Haemoproteus and Leucocytozoon . Only 5.7% of first-brood nestlings were infected, but those in infected nestboxes had a lower heterophil/lymphocyte ratio. This study confirms the pathogenicity of blood parasites to the host by demonstrating negative effects of infection on both physiology and breeding performance.     

Thirteen polymorphic microsatellite loci in the Neotropical fish Prochilodus argenteus (Characiformes,Prochilodontidae)

Prochilodus species inhabit the main river systems of South America and usually present commercial value to inland fishing. In the present study, we describe the isolation and characterization of 13 novel microsatellite loci in Prochilodus argenteus. The number of alleles per polymorphic locus varied from four to 22 and the observed heterozygosity ranged from 0.333 to 0.893. Additionally, cross‐species amplification was successful in two other Prochilodus species. These loci will be useful for studies of the population genetic structure in this fish group.     

Microsatellites loci isolated in the freshwater fish Brycon hilarii

We describe seven microsatellite loci, including tetra‐, tri‐ and dinucleotides, isolated from Brycon hilarii, which is a migratory fish inhabiting the Paraguay River basin (Brazil) and is highly valued for its meat quality. Three to eight alleles per locus were detected and the expected heterozygosity ranged from 0.31 to 0.81. Positive results were obtained with cross‐amplification in five other species of Brycon. These microsatellites provide a potential tool for wild population and aquaculture studies of B. hilarii and other species of the genus.     

Isolation and characterization of microsatellite loci in Cylindrocladium parasiticum

Twelve polymorphic microsatellite markers were developed for Cylindrocladium parasiticum, a plant pathogen with a wide host range and the causal agent of the serious disease of peanuts (Arachis hypogaea) known as cylindrocladium black rot (CBR). Polymorphism was evaluated on 17 isolates from different hosts and regions. Each locus had between two and six alleles. Cross‐species transferability tested for 20 other Cylindrocladium species found amplification only in Cylindrocladium pacificum, which is phylogenetically closely related to C. parasiticum.     

The scaling of colony size with nest volume in termites: a role in population dynamics?

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Isolation and characterization of microsatellite loci in Cylindrocladium pauciramosum

Ten polymorphic microsatellite markers were developed for Cylindrocladium pauciramosum, a plant pathogen with a wide host range, which poses a serious problem in South African Eucalyptus nurseries. Polymorphism was evaluated on 43 isolates collected from Colombia and South Africa. Each locus had between three and six alleles. Testing for random mating showed multilocus equilibrium for a population of 40 isolates from a South African forestry nursery. Cross‐species transferability tested for 19 other Cylindrocladium species found amplification only in C. spathulatum, which is phylogenetically closely related to C. pauciramosum.