Showing papers by "Daniel Sol published in 2015"

Singing in the city: High song frequencies are no guarantee for urban success in birds

Abstract: Urbanization involves dramatic environmental alterations, which can limit survival and reproduction of organisms and contribute to loss of biodiversity. One such alteration is anthropogenic noise, which biases natural ambient noise spectra toward low frequencies where it may interfere with acoustic communication among birds. Because vocalizing at higher frequencies could prevent masking by noise, it has been hypothesized that species with higher song frequencies should be less affected by urbanization. Indeed, evidence is accumulating that urban birds often vocalize at higher frequency than nonurban birds. However, the extent to which singing frequency affects their success in cities is less clear. We tested this hypothesis with a comprehensive phylogenetic Bayesian analysis comparing song frequency of songbirds from 5 continents with 4 measures of success in urbanized environments. Tolerance to urbanization was not associated with dominant or minimum song frequencies, regardless of the metric used to quantify urban success and the intensity of the urban alterations. Although song frequency was related to habitat preferences and body size of the species, none of these factors explained the lack of association with urban success. Singing high may be beneficial for signal perception under noisy conditions, but these high frequencies are apparently no guarantee for the success of bird species in urbanized environments.

Random processes and phylogenetic loss caused by plant invasions

Abstract: Aim Although biological invasions represent a major cause of biodiversity loss, the actual mechanisms driving species extinctions remain insufficiently understood. Here we investigate the role of three processes as drivers of phylogenetic loss in invaded local plant communities, namely the ‘biotic resistance’, ‘environmental filtering’ and ‘functional equivalence’ hypotheses. Location Balearic Islands (western Mediterranean). Methods We quantified the phylogenetic diversity and structure of 109 pairs of invaded and non-invaded local plant communities from two Mediterranean islands. Each pair contained one control plot and one plot invaded either by the deciduous tree Ailanthus altissima, the succulent subshrubs Carpobrotus spp. or the pseudoannual geophyte Oxalis pes-caprae. We combined generalized linear models, analyses of phylogenetic community structure and generalized linear mixed models using a Markov chain Monte Carlo technique (MCMCglmm) to contrast the ‘biotic resistance’, ‘environmental filtering’ and ‘functional equivalence’ hypotheses. Results While the phylogenetic structure of the non-invaded communities was not more clustered or overdispersed than expected by chance, minimum phylogenetic distance to the invasive species increased in invaded assemblages, in which the magnitude of phylogenetic diversity loss ranged from 6 to 37% depending on the invader’s identity. Invader or island identity did not explain the probabilities of native species becoming locally extinct. Rather, the likelihood of extinction was mainly explained by species abundance, with scarcer species exhibiting a higher chance of becoming locally extinct. Species identity explained a small fraction of the variation in extinction risk (12%), independently of each species’ evolutionary history. Main conclusions The most relevant driver of local extinction is a stochastic process where less abundant species tend to disappear more frequently irrespective of their evolutionary history. This has strong implications for conservation because it suggests that in the study region the invaders are unlikely to drive regional and global extinctions except in cases where the native species is already rare.

The Evolution of Innovativeness: Exaptation or Specialized Adaptation?

Abstract: The evolutionary origin of innovative capacities remains contentious. For some authors, innovativeness is an adaptive specialization related to particular modular cognitive processes. However, this hypothesis lacks a plausible evolutionary mechanism. In this chapter, I discuss the alternative that innovativeness is not the direct target of selection, at least in the early stages of evolution, but a by-product of a combination of traits that have evolved for other functions yet predispose individuals to solve problems by adopting novel behaviors (i.e. an exaptation). Evidence is accumulating that (1) the innovation process depends on a combination of adaptations, (2) these adaptations can evolve together in slow-lived species due to shared mechanisms and correlated selection, and (3) enhanced innovativeness can be more directly selected in those slow-lived animals that actively expose themselves to novel problems. The exaptation hypothesis is thus not only more consistent with current evolutionary theory but fits well with empirical evidence.

La experiencia internacional en alta velocidad ferroviaria

Abstract: El presente informe muestra que la alta velocidad es una tecnologia de transporte con presencia internacional pero esta enormemente concentrada en Europa occidental y Asia oriental, aunque existen importantes diferencias en cuanto a dotacion. Espana destaca por su liderazgo en dotacion de infraestructura una vez corregida por poblacion, lo que contrasta con el escaso uso de la misma, muy por debajo del resto de redes de Alta velocidad (AV).