The Genus Uroleucon Mordvilko (Insecta, Aphidoidea) in South America, with a key and descriptions of four new species

Uroleucon is one of only two genera of Aphidinae to have undergone significant speciation in South America, with a group of about 14 endemic, morphologically similar species feeding on native Compositae, especially Baccharis . Multivariate morphometrics (canonical variates analysis, CVA) was used to discriminate between these species and compare them with the North American subgenus Lambersius , in which most of them have hitherto been placed. It is concluded that they probably form a separate monophyletic group. Four new species are described in this group— brevisiphon, essigi, petrohuense and pseudomuennosum— and five names are placed in synonymy. Of the other species of Uroleucon in South America, U. lizerianum is widespread and feeds on many species of native and introduced Compositae; it is morphometrically inseparable from the North American species U. ambrosiae and is probably an introduced form of that species, but has consistently fewer secondary rhinaria. A key is provided to the 19 available species of Uroleucon recorded from South America.     

Colour polymorphism and genetic strains in Avion intermedins from Flores, Azores (Mollusca: Pulmonata)

Thirty specimens of Arion intermedins from Flores (and Corvo) were electrophoretically (PAGE) assayed for 11 enzymes, yielding information about 14 putative loci in two colour morphs of this species. One of these colour variants was tentatively identified as A. pascalianus (P morph). Except for the Mdh locus, all loci in A. intermedins sensu lato from Flores were monomorphic. Mdh , however, was diallelic for Mdh₁₀₀ and Mdh₁₂₂. This latter electromorph was absent in A. intermedins sensu stricto from Flores, but present in the P morph and A. intermedins from Belgium. As a consequence A. intermedins sensu lato from Flores consists of two genetic strains defined by the Mdh alleles. The genetic identity between these strains (7) is 0.929. The genetic identity between the P morph and A. intermedins sensu stricto in Flores is 0.951, while between the P morph and Belgian A. intermedins it is 0.973. These values suggest that the supposed A. pascalianus from Flores is only a colour morph of A. intermedins. This paper also provides the first published record of this species from the island of Corvo.     

Hydrological connectivity structures concordant plant and animal assemblages according to niche rather than dispersal processes

1. Understanding the processes that structure community assembly across landscapes is fundamental to ecology and for predicting and managing the consequences of anthropogenically induced changes to ecosystems. 2. We assessed the community similarity of fish, macroinvertebrate and vegetation communities against geographic distances ranging from 4 to 480 km (i.e. distance–decay relationships) to determine the balance between local environmental factors and regional dispersal processes, and thus whether species‐sorting (niche processes) or dispersal limitation (neutral processes) was more important in structuring these assemblages in Australia’s wet‐dry tropics. We investigated whether the balance between niche and dispersal processes depended on the degree of hydrological connectivity, predicting that dispersal processes would be more important at connected sites, and also whether there was spatial concordance among these three assemblage types. 3. There was significant but weak spatial concordance among the study communities, suggesting limited potential for surrogacy among them. Distance–decay in community similarity was not observed for any study assemblage at perennial sites, suggesting dispersal was not limiting and assemblages were structured more strongly by local niche processes at these connected sites. At intermittent sites, weak distance–decay relationships for each assemblage type were confounded by significant relationships with environmental dissimilarity, suggesting that dispersal limitation contributed, albeit weakly, to niche processes in structuring our three study assemblages at disconnected sites. 4. Two environmental factors, flow regime and channel width, explained significant proportions of variation in all three assemblages, potentially contributing to the observed spatial concordance between them and representing local environmental gradients along which these communities re‐assemble after the wet season, according to niche rather than dispersal processes.     

Large‐sized insects show stronger seasonality than small‐sized ones: a case study of fruit‐feeding butterflies

Animal species have a restricted period during the year when conditions for development are optimal, and this is known as the temporal window. Duration of the temporal window can vary among species, although the causes of variation are still poorly understood. In the present study, examining butterflies, we assume that the temporal window duration is correlated with the seasonal period of flight (termed seasonality). To understand how species characteristics are correlated with this, we examine whether there is a relationship between body size and length of flight period of fruit‐feeding butterflies in forest fragments, and whether these two parameters have a phylogenetic signal. Using wing size as a measure of body size and the period of adult flight as a measure of seasonality, we found significant positive correlations between body size and seasonality among subfamilies but not within subfamilies. We also found a clear phylogenetic signal in size but not in seasonality. The results obtained suggest the existence of a trade‐off between insect size and seasonality, with size limiting flight period length. The relationship between body size and seasonality and the synchrony with their resources may be one factor explaining the vulnerability of large insects to forest fragmentation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 820–827.     

The genomic legacy from the extinct Lepus timidus to the three hare species of Iberia: contrast between mtDNA, sex chromosomes and autosomes

Extensive interspecific genetic introgression is often reported, and appraising its genomic impact can serve to determine whether it results from selection on specific loci or from demographic processes affecting the whole genome. The three species of hares present in the Iberian Peninsula harbour high frequencies of mitochondrial DNA (mtDNA) from Lepus timidus, an arctic/boreal species now extinct in the region. This could result from the invasive replacement of L. timidus by the temperate species during deglaciation but should then have left traces in the nuclear genome. We typed single nucleotide polymorphisms (SNPs) discovered by sequencing 10 autosomal loci, two X-linked and one Y-linked in species-wide samples of the four taxa. Based on lineage-diagnostic SNPs, we detected no trace of L. timidus sex chromosomes in Iberia. From the frequencies of inferred haplotypes, autosomal introgression into L. granatensis appeared mostly sporadic but always widespread instead of restricted to the north as mtDNA. Autosomal introgression into Iberian L. europaeus , inhabiting the Pyrenean foothills, was hardly detectable, despite quasi-fixation of L. timidus mtDNA. L. castroviejoi , endemic to the Cantabrian Mountains and fixed for L. timidus mtDNA, showed little traces of autosomal introgression. The absence of sex-chromosome introgression presumably resulted from X-linked hybrid male unfitness. The contrasting patterns between the autosomes and mtDNA could reflect general gender asymmetric processes such as frequency-dependent female assortative mating, lower mtDNA migration and higher male dispersal, but adaptive mtDNA introgression cannot be dismissed. Additionally, we document reciprocal introgression between L. europaeus and both L. granatensis in Iberia and L. timidus outside Iberia.