Non-random gene flow: An underappreciated force in evolution and ecology

Dispersal is an important life-history trait involved in species persistence, evolution, and diversification, yet is one of the least understood concepts in ecology and evolutionary biology. There is a growing realization that dispersal might not involve the random sample of genotypes as is typically assumed, but instead can be enriched for certain genotypes. Here, we review and compare various sources of such non-random gene flow, and summarize its effects on local adaptation and resource use, metapopulation dynamics, adaptation to climate change, biological invasion, and speciation. Given the possible ubiquity and impacts of non-random gene flow, there is an urgent need for the fields of evolution and ecology to test for non-random gene flow and to more fully incorporate its effects into theory. © 2012 Elsevier Ltd.Peer Reviewe

Managing non-native species: Don't wait until their impacts are proven

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Advancing impact assessments of non-native species: strategies for strengthening the evidence-base

The numbers and impacts of non-native species (NNS) continue to grow. Multiple ranking protocols have been developed to identify and manage the most damaging species. However, existing protocols differ considerably in the type of impact they consider, the way evidence of impacts is included and scored, and in the way the precautionary principle is applied. These differences may lead to inconsistent impact assessments. Since these protocols are considered a main policy tool to promote mitigation efforts, such inconsistencies are undesirable, as they can affect our ability to reliably identify the most damaging NNS, and can erode public support for NNS management. Here we propose a broadly applicable framework for building a transparent NNS impact evidence base. First, we advise to separate the collection of evidence of impacts from the act of scoring the severity of these impacts. Second, we propose to map the collected evidence along a set of distinguishing criteria: where it is published, which methodological approach was used to obtain it, the relevance of the geographical area from which it originates, and the direction of the impact. This procedure produces a transparent and reproducible evidence base which can subsequently be used for different scoring protocols, and which should be made public. Finally, we argue that the precautionary principle should only be used at the risk management stage. Conditional upon the evidence presented in an impact assessment, decision-makers may use the precautionary principle for NNS management under scientific uncertainty regarding the likelihood and magnitude of NNS impacts. Our framework paves the way for an improved application of impact assessments protocols, reducing inconsistencies and ultimately enabling more effective NNS management

Assessment of social perception of an invasive parakeet using a novel visual survey method

The perceptions of the general public regarding invasive alien species (IAS) are important in the prevention of future invasions and the success of management programmes. Here we use a novel visual method to investigate the perception of a charismatic IAS, the rose-ringed parakeet, across different stakeholders in Seville, Spain. Respondents were asked to select images of 10 bird species they would like to have present in their surroundings, out of 20 available images, including the parakeet and three other non-natives. This makes the survey easy, fast to take and attractive to potential participants, while prior and potentially biasing information of survey goals is minimised. Although more than 95% of the respondents recognised the parakeet, at least up to family level, only 34.8% selected it. Selection rates were even lower for three other IAS and even more so when the status of non-native species was indicated next to the images, suggesting that a social norm against IAS may be established. To validate our novel visual approach, we also assessed perception via a traditional questionnaire and the results of the two survey methods coincided. Finally parakeet selection differed importantly amongst pre-defined sectors of the public and people who had prior experience with the parakeet selected it less frequently (e.g. farmers, park managers). These results highlight the importance of studying different stakeholders to get the full picture when considering IAS management programmes. Our new visual survey method can thus serve as an excellent and user-friendly tool to study people's perceptions regarding charismatic IAS and facilitate well-informed and sensible decision-making

Adaptive speciation theory: a conceptual review

Speciation—the origin of new species—is the source of the diversity of life. A theory of speciation is essential to link poorly understood macro-evolutionary processes, such as the origin of biodiversity and adaptive radiation, to well understood micro-evolutionary processes, such as allele frequency change due to natural or sexual selection. An important question is whether, and to what extent, the process of speciation is ‘adaptive’, i.e., driven by natural and/or sexual selection. Here, we discuss two main modelling approaches in adaptive speciation theory. Ecological models of speciation focus on the evolution of ecological differentiation through divergent natural selection. These models can explain the stable coexistence of the resulting daughter species in the face of interspecific competition, but they are often vague about the evolution of reproductive isolation. Most sexual selection models of speciation focus on the diversification of mating strategies through divergent sexual selection. These models can explain the evolution of prezygotic reproductive isolation, but they are typically vague on questions like ecological coexistence. By means of an integrated model, incorporating both ecological interactions and sexual selection, we demonstrate that disruptive selection on both ecological and mating strategies is necessary, but not sufficient, for speciation to occur. To achieve speciation, mating must at least partly reflect ecological characteristics. The interaction of natural and sexual selection is also pivotal in a model where sexual selection facilitates ecological speciation even in the absence of diverging female preferences. In view of these results, it is counterproductive to consider ecological and sexual selection models as contrasting and incompatible views on speciation, one being dominant over the other. Instead, an integrative perspective is needed to achieve a thorough and coherent understanding of adaptive speciation

Can Establishment Success Be Determined through Demographic Parameters? A Case Study on Five Introduced Bird Species

The dominant criterion to determine when an introduced species is established relies on the maintenance of a self-sustaining population in the area of introduction, i.e. on the viability of the population from a demographic perspective. There is however a paucity of demographic studies on introduced species, and establishment success is thus generally determined by expert opinion without undertaking population viability analyses (PVAs). By means of an intensive five year capture-recapture monitoring program (involving \u3e12,000 marked individuals) we studied the demography of five introduced passerine bird species in southern Spain which are established and have undergone a fast expansion over the last decades. We obtained useful estimates of demographic parameters (survival and reproduction) for one colonial species (Ploceus melanocephalus), confirming the long-term viability of its local population through PVAs. However, extremely low recapture rates prevented the estimation of survival parameters and population growth rates for widely distributed species with low local densities (Estrilda troglodytes and Amandava amandava) but also for highly abundant yet non-colonial species (Estrilda astrild and Euplectes afer). Therefore, determining the establishment success of introduced passerine species by demographic criteria alone may often be troublesome even when devoting much effort to field-work. Alternative quantitative methodologies such as the analysis of spatio-temporal species distributions complemented with expert opinion deserve thus their role in the assessment of establishment success of introduced species when estimates of demographic parameters are difficult to obtain, as is generally the case for non-colonial, highly mobile passerines

Lovebirds in the air:trade patterns, establishment success and niche shifts of Agapornis parrots within their non-native range

Understanding the factors influencing the establishment of non-native species is pivotal with regards to the development of effective biosecurity policies. In this paper, we aim to assess the role of climate matching, trade patterns and breeding origin as drivers of establishment success of introduced lovebirds (Agapornis species). A comprehensive database on the worldwide distribution of eight species of non-native lovebirds (including establishment success and population size from 21 countries spanning 27 years) was compiled. We combined climate-based species distribution models with environmental niche analyses to evaluate environmental suitability and potential niche shifts in the introduced range of lovebirds. Then, we tested whether combining habitat suitability with information on trade, introduction effort and breeding origin (captive-bred or wild-caught) of imported birds can improve model predictions at the country level. Although climate-based models fit well with the current distribution of non-native lovebirds at 5-arcminute resolution and significant niche similarity was found for 3 species, we also observed successful establishments in areas climatically distinct from those occupied in native ranges. At the country level, only a significant relationship between the number of established populations and both the number of introduction sites and the year of first importation was observed. A significant effect of breeding origin was not found, but most traded birds had a captive-bred origin. Our work contributes to the growing evidence of the complexity of the invasion process and the difficulty of pre-introduction invasion assessments based solely on the characteristics of the recipient environments for the Agapornis species. Surveillance protocols should be applied to both wild-caught and captive-bred lovebirds, as additional data becomes available to better tease apart the role of origin in those species.The realisation of this manuscript was supported by the European Cooperation in Science and Technology COST Action ES1304 (ParrotNet). The contents of this paper are the authors’ responsibility and neither COST nor any person acting on its behalf is responsible for the use that might be made of the information contained in it. Luís Reino was funded by FEDER Funds through the Operational Competitiveness Factors Program “COMPETE”, and by National Funds through the Foundation for Science and Technology (FCT) within the framework of the Project “PTDC/AAG-GLO/0463/2014-POCI-01-0145-FEDER-016583” and FCT Post-doc Grant SFRH/BPD/93079/2013. LC was funded by the H2020-MSCA-IF-2016 fellowship No. 752149.Peer reviewe

Apparent selective advantage of leucism in a coastal population of Southern caracaras (Falconidae)

ABSTRACT Background: Southern caracaras are medium-sized raptors with a large range stretching to the southern tip of South America. An aberrant, leucistic plumage is found commonly along the coast of Chubut Province (Patagonia, Argentina). Leucistic birds do not produce dark melanin in their feathers. However, they are not albinos because their eyes are not red. No genetic studies of caracara plumages are known. Hypothesis: The high frequency of leucistic birds in Chubut Province arises because of natural selection. Methods: Map the distribution of leucistic individuals relative to normal individuals. Combine a variety of anecdotal natural history observations, collected over 20 years, into a logical inference. Observations: Leucistic caracaras were found only along a 250-km stretch of rocky oceanic islands and continental outcrops with large seabird colonies in Chubut Province. In the rest of their range, Southern caracaras have dark plumage. Where they do occur, leucistic birds are frequent and co-occur with dark-plumaged birds. Intermediate individuals, presumabl

Dispersal in a changing world: opportunities, insights and challenges

Abstract It has been long recognised that dispersal is an important life-history trait that plays a key role in the demography and evolution of populations and species. This then suggests that dispersal play a central role in the response of populations and species to ever-increasing global change, including climate change, habitat loss and fragmentation, and biological invasions. During a symposium held at Lund University (Sweden), the causes and consequences of dispersal were discussed, and here we provide an overview of the talks. As the discussions often gravitated towards the role and our understanding of dispersal in a changing world and given the urgent challenges posed by it, we place this overview in the context of global change. We draw and discuss four conclusions: (i) methodological advances provide opportunities for improved future studies, (ii) dispersal distances can be much greater than previously thought (examples in plants and vertebrates), but also much more restricted (examples in micro-organisms), (iii) dispersal is more dynamic than we often care to admit (e.g. due to individual variation, effects of parasites, variation in life history, developmental and evolutionary responses, community impacts), (iv) using results of dispersal research for detailed prediction of outcomes under global change is currently mostly out of reach – nevertheless, that should not stop us from showing the many negative consequences of global change, and how dispersal is often a limiting factor in adapting to this.This work has been supported by a Linnaeus grant to the Centre for Animal Movement Research (CAnMove) from the Swedish Research Council (349-2007-8690) and Lund University.Peer Reviewe