UV-reflectivity of parafocal eyespot elements on butterfly wings in normal and abnormal specimens

An unusual specimen of Aglais urticae, lacking characteristic UV-reflecting parafocal eyespot elements along the margins of both fore and hind wings, is compared with normal, wild-type specimens. Wing scales, responsible for generating structural coloration, aremissing in the abnormal individual and have been replaced with a type that is typical of pigment-based colours. Other modifications seen in the abnormal specimen include firstly, a distal expansion of a uniformly brown region, that otherwise occupies a proximal position on the hind wings of the wild type, and secondly, the lack of a characteristic orange cross-vein band that runs proximal to the parafocal eyespot elements on the hindwing. The differences in coloration between abnormal and wild type are seen as evidence of a proximal-distal developmental axis (originally proposed by Nijhout 1991) and support a view recently aired by Beldade and Brakefield (2003). It is now clear that studies on butterfly eyespot development must consider not only pigmentcontaining scales, but also the structurallymodified scales responsible for physical colours, i.e. UV reflectivity

Nuclear versus mitochondrial DNA: evidence for hybridization in colobine monkeys

<p>Abstract</p> <p>Background</p> <p>Colobine monkeys constitute a diverse group of primates with major radiations in Africa and Asia. However, phylogenetic relationships among genera are under debate, and recent molecular studies with incomplete taxon-sampling revealed discordant gene trees. To solve the evolutionary history of colobine genera and to determine causes for possible gene tree incongruences, we combined presence/absence analysis of mobile elements with autosomal, X chromosomal, Y chromosomal and mitochondrial sequence data from all recognized colobine genera.</p> <p>Results</p> <p>Gene tree topologies and divergence age estimates derived from different markers were similar, but differed in placing <it>Piliocolobus/Procolobus </it>and langur genera among colobines. Although insufficient data, homoplasy and incomplete lineage sorting might all have contributed to the discordance among gene trees, hybridization is favored as the main cause of the observed discordance. We propose that African colobines are paraphyletic, but might later have experienced female introgression from <it>Piliocolobus</it>/<it>Procolobus </it>into <it>Colobus</it>. In the late Miocene, colobines invaded Eurasia and diversified into several lineages. Among Asian colobines, <it>Semnopithecus </it>diverged first, indicating langur paraphyly. However, unidirectional gene flow from <it>Semnopithecus </it>into <it>Trachypithecus </it>via male introgression followed by nuclear swamping might have occurred until the earliest Pleistocene.</p> <p>Conclusions</p> <p>Overall, our study provides the most comprehensive view on colobine evolution to date and emphasizes that analyses of various molecular markers, such as mobile elements and sequence data from multiple loci, are crucial to better understand evolutionary relationships and to trace hybridization events. Our results also suggest that sex-specific dispersal patterns, promoted by a respective social organization of the species involved, can result in different hybridization scenarios.</p

Genetic parameters for eight microsatellite loci in <i>Rhinopithecus brelichi</i>.

<p>N_a  =  no. of alleles; N_e  =  no. of effective alleles; H_o  =  observed heterozygosity; H_e  =  expected heterozygosity; F_is  =  fixation index; * = p<0.05.</p

Geographical position of FNNR (marked by a black dot) in Guizhou Province, China (A) and a sketch of FNNR (B).

<p>Collection of samples for genetic analyses was carried out in the gray region around the Yangaoping field station.</p

Bayesian Skyline Plot (BSP) displaying changes in female effective population size (N_ef) through time in <i>R. brelichi</i>.

<p>Calculations are based on 603 bp of the mitochondrial HVI region. Shown are the median (black) and the 95% highest posterior probability density (dashed lines) around the estimate. The arrow indicates the start of a reduction in N_ef.</p

Expected (H_e) and observed (H_o) heterozygosity across six loci for <i>Rhinopithecus brelichi</i> and <i>R. bieti</i> (data for <i>R. bieti</i> from Liu et al. [46]).

<p>Expected (H_e) and observed (H_o) heterozygosity across six loci for <i>Rhinopithecus brelichi</i> and <i>R. bieti</i> (data for <i>R. bieti</i> from Liu et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073647#pone.0073647-Liu1" target="_blank">[46]</a>).</p

Scenario explaining discrepancies between mtDNA and nDNA diversity in <i>R. brelichi</i>.

<p>In historical times, <i>R. brelichi</i> was distributed over a larger area than today comprising several subpopulations or demes (A–G) with respective different mtDNA haplogroup assemblages. Due to male migration between these demes, nDNA was transferred between them and equalized nDNA diversity among demes, but not so for mtDNA. After partial habitat and population loss in this example only one deme survived (E; dashed circles), containing just a subset of the original mtDNA haplotypes but almost all nDNA diversity. Thus, mtDNA diversity was strongly reduced while nDNA diversity remained comparatively high.</p

Allele frequency distribution for eight microsatellite loci in <i>Rhinopithecus brelichi</i> (n = 141 individuals).

<p>Bars represent the proportion of alleles found in each allele frequency class. The distribution is L-shaped, as expected for a stable population under mutation-drift equilibrium, thus not indicating a recent bottleneck.</p