Molecular phylogenetics of the neotropical butterfly subtribe Oleriina (Nymphalidae: Danainae: Ithomiini).

The Oleriina is one of the most speciose subtribes of the neotropical nymphalid butterfly tribe Ithomiini. They are widely distributed across the Andes and Amazonian lowlands and like other ithomiines they are involved in complex mimicry rings. This subtribe is of particular interest because it contains the most diverse ithomiine genus, Oleria, as well as two genera, Megoleria and Hyposcada, that feed on hostplants not utilized elsewhere in the tribe. Here we present the first comprehensive species-level phylogeny for the Oleriina, representing 83% of recognised species in the group, and based on 6698bp from eight mitochondrial (mt) and nuclear (nc) genes. Topologies are largely congruent for ncDNA and the concatenated dataset and the genera Oleria, Hyposcada and Megoleria are recovered and well-supported, although strongly discordant genealogy between mtDNA and ncDNA suggest possible introgression among Hyposcada and Megoleria. A fourth clade containing the type species of Ollantaya is consistently recovered, and this recently synonymized name is resurrected. Clear subdivisions within Oleria separate the genus into four species groups, onega, amalda, makrena and aegle, which also correspond to differing biogeographic and elevation range characteristics. Unlike other ithomiine genera, the Oleriina show homogeneity in mimetic wing pattern, in sharp contrast to the emerging paradigm that mimetic shifts have enhanced diversification in the tribe. Our results show a potentially more important role for geographic isolation in the diversification of the Oleriina compared to other Ithomiini studied to date and provide a framework for more detailed biogeographical studies, in addition to a rare opportunity for comparative analyses with other neotropical groups.

Strikingly variable divergence times inferred across an Amazonian butterfly 'suture zone'.

'Suture zones' are areas where hybrid and contact zones of multiple taxa are clustered. Such zones have been regarded as strong evidence for allopatric divergence by proponents of the Pleistocene forest refugia theory, a vicariance hypothesis frequently used to explain diversification in the Amazon basin. A central prediction of the refugia and other vicariance theories is that the taxa should have a common history so that divergence times should be coincident among taxa. A suture zone for Ithomiinae butterflies near Tarapoto, NE Peru, was therefore studied to examine divergence times of taxa in contact across the zone. We sequenced 1619bp of the mitochondrial COI/COII region in 172 individuals of 31 species from across the suture zone. Inferred divergence times differed remarkably, with divergence between some pairs of widespread species (each of which may have two or more subspecies interacting in the zone, as in the genus Melinaea) being considerably less than that between hybridizing subspecies in other genera (for instance in Oleria). Our data therefore strongly refute a simple hypothesis of simultaneous vicariance and suggest that ongoing parapatric or other modes of differentiation in continuous forest may be important in driving diversification in Amazonia.

Molecular systematics of the butterfly genus Ithomia (Lepidoptera: Ithomiinae): a composite phylogenetic hypothesis based on seven genes.

Butterflies in the nymphalid subfamily Ithomiinae are brightly colored and involved in mimicry. Here we present a phylogenetic hypothesis for 23 of the 24 species in the genus Ithomia, based on seven different gene regions, representing 5 linkage groups and 4469 bp. We sequenced varying length regions of the following genes: (1) elongation factor 1alpha (Ef1alpha; 1028 bp); (2) tektin (tektin; 715 bp); (3) wingless (wg; 405 bp); (4) ribosomal protein L5 (RpL5; 722 bp, exons 1, 2, 3, and introns 1 and 2); and (5) mitochondrial cytochrome oxidase I, II (Co1 and Co2 and intervening leucine tRNA; 1599 bp). The results show incongruence between some genetic loci, although when alternate topologies are compared statistically it was generally true that one topology was supported by a majority of loci sampled. This highlights the need to sample widely across the genome in order to obtain a well-supported phylogenetic hypothesis. A combined evidence topology is presented based on a Bayesian analysis of all the gene regions, except the fast-evolving RpL5. The resulting hypothesis is concordant with the most probable relationships determined from our topological comparisons, although in some parts of the tree relationships remain weakly supported. The tree suggests diversification has largely occurred within biogeographic regions such as Central America, the Amazon, the southern and northern Andes, with only occasional dispersal (or vicariance) between such regions. This phylogenetic hypothesis can now be used to investigate patterns of diversification across the genus, such as the potential role of color pattern changes in speciation.

Isolation of novel olfactory receptor genes in marmosets (Callithrix): insights into pseudogene formation and evidence for functional degeneracy in non-human primates.

Nineteen olfactory receptor (OR) genes were isolated from three OR subfamilies in two species of marmoset (Callithrix). Olfactory receptor 912-93 has high sequence similarity among marmosets and between marmosets and humans, suggesting strong conservation of function. All of the remaining seventeen OR genes identified from subfamilies 3A and 1E were pseudogenes. Following pseudogene formation, marmoset OR genes in both 1E and 3A subfamilies underwent duplications, indel events and a high rate of nucleotide substitution. These results provide a contrast to previous studies, and show that in spite of the keen olfactory sense of marmosets, they harbour many OR pseudogenes. A high rate of in vitro recombination using Pfu polymerase but not Taq polymerase was confirmed. The rapid molecular evolution of OR pseudogenes suggests that they do not provide a useful source of sequence variation for conversion to intact OR genes over evolutionary timescales. The overall pattern of OR evolution in marmosets is comparable to the 'birth-and-death' model of gene family evolution. An unbiased view on the evolutionary timing of the reduction of the functional olfactory repertoire in humans must await more data.