Similar local, but different systemic, metabolomic responses of closely related pine subspecies to folivory by caterpillars of the processionary moth.

Plants respond locally and systemically to herbivore attack. Most of the research conducted on plant-herbivore relationships at element and molecular levels have focused on the elemental composition or/and certain molecular compounds or specific families of defence metabolites showing that herbivores tend to select plant individuals or species with higher nutrient concentrations and avoid those with higher levels of defence compounds. We performed stoichiometric and metabolomics, both local and systemic, analyses in two subspecies of Pinus sylvestris under attack from caterpillars of the pine processionary moth, an important pest in the Mediterranean Basin. Both pine subspecies responded locally to folivory mainly by increasing relative concentrations of terpenes and some phenolics. Systemic responses differed between pine subspecies, and most of the metabolites presented intermediate concentrations between those of the affected parts and unattacked trees. Our results support the hypothesis that foliar nutrient concentrations are not a key factor for plant selection by adult female processionary moths for oviposition, since folivory was not associated with any of the elements analysed. Phenolic compounds generally did not increase in the attacked trees, questioning the suggestion of induction of phenolics following folivory attack and the anti-feeding properties of phenolics. Herbivory attack produced a general systemic shift in pines, in both primary and secondary metabolism, which was less intense and chemically different from the local responses. Local pine responses were similar between pine subspecies, while systemic responses were more distant.

Repeated evolution of exaggerated dewlaps and other throat morphology in lizards.

The existence of elaborate ornamental structures in males is often assumed to reflect the outcome of female mate choice for showy males. However, female mate choice appears weak in many iguanian lizards, but males still exhibit an array of ornament-like structures around the throat. We performed a phylogenetic comparative study to assess whether these structures have originated in response to male-male competition or the need for improved signal efficiency in visually difficult environments. We found little evidence for the influence of male-male competition. Instead, forest species were more likely to exhibit colourful throat appendages than species living in open habitats, suggesting selection for signal efficiency. On at least three independent occasions, throat ornamentation has become further elaborated into a large, conspicuously coloured moving dewlap. Although the function of the dewlap is convergent, the underlying hyoid apparatus has evolved very differently, revealing the same adaptive outcome has been achieved through multiple evolutionary trajectories. More generally, our findings highlight that extravagant, ornament-like morphology can evolve in males without the direct influence of female mate choice and that failure to consider alternative hypotheses for the evolution of these structures can obscure the true origins of signal diversity among closely related taxa.

Key innovations and island colonization as engines of evolutionary diversification: a comparative test with the Australasian diplodactyloid geckos.

The acquisition of key innovations and the invasion of new areas constitute two major processes that facilitate ecological opportunity and subsequent evolutionary diversification. Using a major lizard radiation as a model, the Australasian diplodactyloid geckos, we explored the effects of two key innovations (adhesive toepads and a snake-like phenotype) and the invasion of new environments (island colonization) in promoting the evolution of phenotypic and species diversity. We found no evidence that toepads had significantly increased evolutionary diversification, which challenges the common assumption that the evolution of toepads has been responsible for the extensive radiation of geckos. In contrast, a snakelike phenotype was associated with increased rates of body size evolution and, to a lesser extent, species diversification. However, the clearest impact on evolutionary diversification has been the colonization of New Zealand and New Caledonia, which were associated with increased rates of both body size evolution and species diversification. This highlights that colonizing new environments can drive adaptive diversification in conjunction or independently of the evolution of a key innovation. Studies wishing to confirm the putative link between a key innovation and subsequent evolutionary diversification must therefore show that it has been the acquisition of an innovation specifically, not the colonization of new areas more generally, that has prompted diversification.

Molecular phylogenetics and historical biogeography of the west-palearctic common toads (Bufo bufo species complex).

In most pan-Eurasiatic species complexes, two phenomena have been traditionally considered key processes of their cladogenesis and biogeography. First, it is hypothesized that the origin and development of the Central Asian Deserts generated a biogeographic barrier that fragmented past continuous distributions in Eastern and Western domains. Second, Pleistocene glaciations have been proposed as the main process driving the regional diversification within each of these domains. The European common toad and its closest relatives provide an interesting opportunity to examine the relative contributions of these paleogeographic and paleoclimatic events to the phylogeny and biogeography of a widespread Eurasiatic group. We investigate this issue by applying a multiproxy approach combining information from molecular phylogenies, a multiple correspondence analysis of allozyme data and species distribution models. Our study includes 304 specimens from 164 populations, covering most of the distributional range of the Bufo bufo species complex in the Western Palearctic. The phylogenies (ML and Bayesian analyses) were based on a total of 1988 bp of mitochondrial DNA encompassing three genes (tRNAval, 16S and ND1). A dataset with 173 species of the family Bufonidae was assembled to estimate the separation of the two pan-Eurasiatic species complexes of Bufo and to date the main biogeographic events within the Bufo bufo species complex. The allozyme study included sixteen protein systems, corresponding to 21 presumptive loci. Finally, the distribution models were based on maximum entropy. Our distribution models show that Eastern and Western species complexes are greatly isolated by the Central Asian Deserts, and our dating estimates place this divergence during the Middle Miocene, a moment in which different sources of evidence document a major upturn of the aridification rate of Central Asia. This climate-driven process likely separated the Eastern and Western species. At the level of the Western Palearctic, our dating estimates place most of the deepest phylogenetic structure before the Pleistocene, indicating that Pleistocene glaciations did not have a major role in splitting the major lineages. At a shallow level, the glacial dynamics contributed unevenly to the genetic structuring of populations, with a strong influence in the European-Caucasian populations, and a more relaxed effect in the Iberian populations.