The roles of hybridization and habitat fragmentation in the evolution of Brazil's enigmatic longwing butterflies, Heliconius nattereri and H. hermathena.

BACKGROUND: Heliconius butterflies are widely distributed across the Neotropics and have evolved a stunning array of wing color patterns that mediate Müllerian mimicry and mating behavior. Their rapid radiation has been strongly influenced by hybridization, which has created new species and allowed sharing of color patterning alleles between mimetic species pairs. While these processes have frequently been observed in widespread species with contiguous distributions, many Heliconius species inhabit patchy or rare habitats that may strongly influence the origin and spread of species and color patterns. Here, we assess the effects of historical population fragmentation and unique biology on the origins, genetic health, and color pattern evolution of two rare and sparsely distributed Brazilian butterflies, Heliconius hermathena and Heliconius nattereri. RESULTS: We assembled genomes and re-sequenced whole genomes of eight H. nattereri and 71 H. hermathena individuals. These species harbor little genetic diversity, skewed site frequency spectra, and high deleterious mutation loads consistent with recent population bottlenecks. Heliconius hermathena consists of discrete, strongly isolated populations that likely arose from a single population that dispersed after the last glacial maximum. Despite having a unique color pattern combination that suggested a hybrid origin, we found no genome-wide evidence that H. hermathena is a hybrid species. However, H. hermathena mimicry evolved via introgression, from co-mimetic Heliconius erato, of a small genomic region upstream of the color patterning gene cortex. CONCLUSIONS: Heliconius hermathena and H. nattereri population fragmentation, potentially driven by historical climate change and recent deforestation, has significantly reduced the genetic health of these rare species. Our results contribute to a growing body of evidence that introgression of color patterning alleles between co-mimetic species appears to be a general feature of Heliconius evolution.

Serologic survey of infectious diseases in populations of maned wolf (Chrysocyon brachyurus) and crab-eating fox (Cerdocyon thous) from Aguas Emendadas Ecological Station, Brazil.

Domestic dogs are reservoirs for many infectious diseases and may represent a potential source of infection for wild canid populations. A serologic investigation of antibodies to Toxoplasma gondii, Neospora caninum, Brucella abortus, and Leptospira spp. was conducted on three maned wolves (Chrysocyon brachyurus) and seven crab-eating foxes (Cerdocyon thous), all free-living, at the Aguas Emendadas Ecological Station (ESECAE), Federal District, Brazil, between February and October 2006. Out of the 10 samples analyzed, eight (80%) were seropositive for T. gondii: 3/3 (100%) of the maned wolves and 5/7 (71.4%) of the crab-eating foxes. None of the animals presented anti-N. caninum, B. abortus, and Leptospira spp. antibodies. This study demonstrated that the wild canid populations at ESECAE presented high exposure to T. gondii and indicated that there is high environmental contamination at the Station, which can be attributed to its proximity to urban zones, the presence of domestic cats in the study area, or the existence of other wild infected felines.

DNA barcoding meets molecular scatology: short mtDNA sequences for standardized species assignment of carnivore noninvasive samples.

Although species assignment of scats is important to study carnivore biology, there is still no standardized assay for the identification of carnivores worldwide, which would allow large-scale routine assessments and reliable cross-comparison of results. Here, we evaluate the potential of two short mtDNA fragments [ATP6 (126 bp) and cytochrome oxidase I gene (COI) (187 bp)] to serve as standard markers for the Carnivora. Samples of 66 species were sequenced for one or both of these segments. Alignments were complemented with archival sequences and analysed with three approaches (tree-based, distance-based and character-based). Intraspecific genetic distances were generally lower than between-species distances, resulting in diagnosable clusters for 86% (ATP6) and 85% (COI) of the species. Notable exceptions were recently diverged species, most of which could still be identified using diagnostic characters and uniqueness of haplotypes or by reducing the geographic scope of the comparison. In silico analyses were also performed for a 110-bp cytochrome b (cytb) segment, whose identification success was lower (70%), possibly due to the smaller number of informative sites and/or the influence of misidentified sequences obtained from GenBank. Finally, we performed case studies with faecal samples, which supported the suitability of our two focal markers for poor-quality DNA and allowed an assessment of prey DNA co-amplification. No evidence of prey DNA contamination was found for ATP6, while some cases were observed for COI and subsequently eliminated by the design of more specific primers. Overall, our results indicate that these segments hold good potential as standard markers for accurate species-level identification in the Carnivora.