Browsing by Autor "Mauricio Linares"

Now showing 1 - 3 of 3

Multiple sources of reproductive isolation in a bimodal butterfly hybrid zone
(Oxford University Press, 2010) ASTRID G. MUÑOZ; Camilo Salazar; Juan Manuel Gonzales Castano; Chris D. Jiggins; Mauricio Linares
An important evolutionary question concerns whether one or many barriers are involved in the early stages of speciation. We examine pre- and post-zygotic reproductive barriers between two species of butterflies (Heliconius erato chestertonii and H. e. venus) separated by a bimodal hybrid zone in the Cauca Valley, Colombia. We show that there is both strong pre- and post-mating reproductive isolation, together leading to a 98% reduction in gene flow between the species. Pre-mating isolation plays a primary role, contributing strongly to this isolation (87%), similar to previous examples in Heliconius. Post-mating isolation was also strong, with absence of Haldane's rule, but an asymmetric reduction in fertility (< 11%) in inter-specific crosses depending on maternal genotype. In summary, this is one of the first examples of post-zygotic reproductive isolation playing a significant role in early stages of parapatric speciation in Heliconius and demonstrates the importance of multiple barriers to gene flow in the speciation process.
Phylogenetic Discordance at the Species Boundary: Comparative Gene Genealogies Among Rapidly Radiating Heliconius Butterflies
(Oxford University Press, 2002) Margarita Beltrán; Chris D. Jiggins; Vanessa Bull; Mauricio Linares; James Mallet; W. Owen McMillan; Eldredge Bermingham
Recent adaptive radiations provide excellent model systems for understanding speciation, but rapid diversification can cause problems for phylogenetic inference. Here we use gene genealogies to investigate the phylogeny of recent speciation in the heliconiine butterflies. We sequenced three gene regions, intron 3 ( approximately 550 bp) of sex-linked triose-phosphate isomerase (Tpi), intron 3 ( approximately 450 bp) of autosomal mannose-phosphate isomerase (Mpi), and 1,603 bp of mitochondrial cytochrome oxidase subunits I and II (COI and COII), for 37 individuals from 25 species of Heliconius and related genera. The nuclear intron sequences evolved at rates similar to those of mitochondrial coding sequences, but the phylogenetic utility of introns was restricted to closely related geographic populations and species due to high levels of indel variation. For two sister species pairs, Heliconius erato-Heliconius himera and Heliconius melpomene-Heliconius cydno, there was highly significant discordance between the three genes. At mtDNA and Tpi, the hypotheses of reciprocal monophyly and paraphyly of at least one species with respect to its sister could not be distinguished. In contrast alleles sampled from the third locus, Mpi, showed polyphyletic relationships between both species pairs. In all cases, recent coalescence of mtDNA lineages within species suggests that polyphyly of nuclear genes is not unexpected. In addition, very similar alleles were shared between melpomene and cydno, implying recent gene flow. Our finding of discordant genealogies between genes is consistent with models of adaptive speciation with ongoing gene flow and highlights the need for multiple locus comparisons to resolve phylogeny among closely related species.
Two sisters in the same dress: Heliconius cryptic species
(Springer Science+Business Media, 2008) Nathalia Giraldo; Camilo Salazar; Chris D. Jiggins; Eldredge Bermingham; Mauricio Linares
We hypothesize that these species might have resulted from recent convergence in colour pattern, perhaps facilitated by hybrid introgression of wing pattern genes.