Changes in species' distributions during and after environmental change: which eco‐evolutionary processes matter more?

Improving our capacity for predicting range shifts requires improved theory exploring the interplay between ecological and evolutionary processes and the (changing) environment. We introduce an individual‐based model incorporating simple stage structure and genetically determined resource allocation rules. Population dynamics are mediated by the resources available and the individual's genetics, and density dependence emerges solely as a consequence of resource levels decreasing as population density increases. Running the model for a set of stylised range‐expansion scenarios reveals the extent to which eco‐evolutionary processes can matter: spatial assortment of individuals possessing effective range expansion strategies (higher dispersal propensity, semelparity rather than iteroparity) can substantially accelerate range advance, and this is more important than the contribution of novel mutations arising during range expansion. In simulations of range expansion there is a greater risk of extinction when all individuals are given the mean strategy evolved in a stationary range. Additionally, our results demonstrate that the erosion of inter‐individual variability during a range‐shift can depress population abundance for lengthy periods, even after the climate has stabilised. Our theoretical results highlight the importance of accounting for inter‐individual variability in future predictive modelling of species' responses to environmental change.     

Exploring lake ecosystems: hierarchy responses to long‐term change?

Shifts in climate regime have provoked substantial trophic‐ and species‐dependent changes within ecosystems. With growing concerns of present global warming, we examined potential lake ecosystem responses, natural hierarchy responses (i.e. immediate responses at lower system levels as opposed to delayed responses at higher system levels), and possible shifts among abiotic (physics, nutrients) and biotic (phytoplankton, zooplankton) system components. Specifically, we analyzed decadal data collected from Müggelsee, a lake in Berlin, Germany, for climate‐induced abiotic and biotic changes, their timing and type, and classified them as abrupt permanent, gradual permanent, abrupt temporary, or monotonic. We further categorized variable changes as a function of system hierarchy, including lake physics (ice, temperature, stratification), nutrients (phosphorus, nitrogen, silicate), plankton, and levels of integration (i.e. species, taxonomic groups, and total plankton). Contrary to current theory, data suggest abrupt responses did not occur in a hierarchy‐dependent manner, nor was a clear pattern observed among functional system‐based categories. Abrupt permanent changes were the most prominent response pattern observed, suggesting they may be driven by large‐scale climatic oscillations and by surpassed thresholds, as noted in previous case studies. Gradual changes coincided with affected abiotic parameters spanning an expansive time range; for example, climatic effects in spring preceded changes in nutrient limitation. Variables displaying no long‐term changes pointed to compensation processes caused by, e.g., simultaneously acting forces of warming trends and climate‐independent changes in trophic state. Nevertheless, the complexity of response patterns at the single system level manifested clear chronological regime shifts in abiotic and biotic parameters in spring and, to a lesser extent, in summer. With regard to projected global warming, the majority of currently unaffected system levels may face impending thermal thresholds, achievement of which would result in an accelerated shift in ecosystem state.     

Short telomeres in short‐lived males: what are the molecular and evolutionary causes?

Telomere length regulation is an important aspect of cell maintenance in eukaryotes, since shortened telomeres can lead to a number of defects, including impaired cell division. Although telomere length is correlated with lifespan in some bird species, its possible role in aging and lifespan determination is still poorly understood. Here we investigate telomere dynamics (changes in telomere length and attrition rate) and telomerase activity in the ant Lasius niger, a species in which different groups of individuals have evolved extraordinarily different lifespans. We found that somatic tissues of the short-lived males had dramatically shorter telomeres than those of the much longer-lived queens and workers. These differences were established early during larval development, most likely through faster telomere shortening in males compared with females. Workers did not, however, have shorter telomeres than the longer-lived queens. We discuss various molecular mechanisms that are likely to cause the observed sex-specific telomere dynamics in ants, including cell division, oxidative stress and telomerase activity. In addition, we discuss the evolutionary causes of such patterns in ants and in other species.     

How do climate change experiments alter plot‐scale climate?

To understand and forecast biological responses to climate change, scientists frequently use field experiments that alter temperature and precipitation. Climate manipulations can manifest in complex ways, however, challenging interpretations of biological responses. We reviewed publications to compile a database of daily plot‐scale climate data from 15 active‐warming experiments. We find that the common practices of analysing treatments as mean or categorical changes (e.g. warmed vs. unwarmed) masks important variation in treatment effects over space and time. Our synthesis showed that measured mean warming, in plots with the same target warming within a study, differed by up to 1.6 C (63% of target), on average, across six studies with blocked designs. Variation was high across sites and designs: for example, plots differed by 1.1 C (47% of target) on average, for infrared studies with feedback control (n = 3) vs. by 2.2 C (80% of target) on average for infrared with constant wattage designs (n = 2). Warming treatments produce non‐temperature effects as well, such as soil drying. The combination of these direct and indirect effects is complex and can have important biological consequences. With a case study of plant phenology across five experiments in our database, we show how accounting for drier soils with warming tripled the estimated sensitivity of budburst to temperature. We provide recommendations for future analyses, experimental design, and data sharing to improve our mechanistic understanding from climate change experiments, and thus their utility to accurately forecast species’ responses.     

What do evolutionary researchers believe about human psychology and behavior?

We investigated the prevalence of beliefs in several key and contested aspects of human psychology and behavior in a broad sample of evolutionary-informed scholars (N = 581). Nearly all participants believed that developmental environments substantially shape human adult psychology and behavior, that there are differences in human psychology and behavior based on sex differences from sexual selection, and that there are individual differences in human psychology and behavior resulting from different genotypes. About three-quarters of participants believed that there are population differences from dissimilar ancestral ecologies/environments and within-person differences across the menstrual cycle. Three-fifths believed that the human mind consists of domain-specific, context-sensitive modules. About half of participants believed that behavioral and cognitive aspects of human life history vary along a unified fast-slow continuum. Two-fifths of participants believed that group-level selection has substantially contributed to human evolution. Results indicate that there are both shared core beliefs as well as phenomena that are accepted by varying proportions of scholars. Such patterns represent the views of contemporary scholars and the current state of the field. The degree of acceptance for some phenomena may change over time as evolutionary science advances through the accumulation of empirical evidence.     

Is post‐feeding thermotaxis advantageous in elasmobranch fishes?

The effects of post‐feeding thermotaxis on ileum evacuation and absorption rates were examined in the laboratory using two elasmobranch species, the Atlantic stingray Dasyatis sabina, which inhabits thermally variable environments, and the whitespotted bamboo shark Chiloscyllium plagiosum, a stenothermic fish living on Indo‐Pacific reefs. Experiments at temperatures similar to those experienced in nature revealed temperature change had no significant effect on C. plagiosum absorption or evacuation rates, suggesting stenothermic sharks cannot exploit temperature differences as a means to improve digestion efficiency. On the other hand, D. sabina showed significantly lower evacuation and absorption rates at lower temperatures. The relative decrease was greater for evacuation (Q₁₀ = 3·08) than absorption rates (Q₁₀ = 2·20), resulting in a significant increase in total absorption, suggesting D. sabina can benefit from using shuttling behaviour to exploit thermal variability in their environment to maximize energetic uptake.     

What is the risk‐benefit ratio of long‐term antipsychotic treatment in people with schizophrenia?

The long‐term benefit‐to‐risk ratio of sustained antipsychotic treatment for schizophrenia has recently been questioned. In this paper, we critically examine the literature on the long‐term efficacy and effectiveness of this treatment. We also review the evidence on the undesired effects, the impact on physical morbidity and mortality, as well as the neurobiological correlates of chronic exposure to antipsychotics. Finally, we summarize factors that affect the risk‐benefit ratio. There is consistent evidence supporting the efficacy of antipsychotics in the short term and mid term following stabilization of acute psychotic symptoms. There is insufficient evidence supporting the notion that this effect changes in the long term. Most, but not all, of the long‐term cohort studies find a decrease in efficacy during chronic treatment with antipsychotics. However, these results are inconclusive, given the extensive risk of bias, including increasing non‐adherence. On the other hand, long‐term studies based on national registries, which have lower risk of bias, find an advantage in terms of effectiveness during sustained antipsychotic treatment. Sustained antipsychotic treatment has been also consistently associated with lower mortality in people with schizophrenia compared to no antipsychotic treatment. Nevertheless, chronic antipsychotic use is associated with metabolic disturbance and tardive dyskinesia. The latter is the clearest undesired clinical consequence of brain functioning as a potential result of chronic antipsychotic exposure, likely from dopaminergic hypersensitivity, without otherwise clear evidence of other irreversible neurobiological changes. Adjunctive psychosocial interventions seem critical for achieving recovery. However, overall, the current literature does not support the safe reduction of antipsychotic dosages by 50% or more in stabilized individuals receiving adjunctive psychosocial interventions. In conclusion, the critical appraisal of the literature indicates that, although chronic antipsychotic use can be associated with undesirable neurologic and metabolic side effects, the evidence supporting its long‐term efficacy and effectiveness, including impact on life expectancy, outweighs the evidence against this practice, overall indicating a favorable benefit‐to‐risk ratio. However, the finding that a minority of individuals diagnosed initially with schizophrenia appear to be relapse free for long periods, despite absence of sustained antipsychotic treatment, calls for further research on patient‐level predictors of positive outcomes in people with an initial psychotic presentation.     

Is fencing enough? The short‐term effects of stock exclusion in remnant grassy woodlands in southern NSW

Summary Fencing remnant native vegetation has become a widespread activity for arresting declines in biodiversity in agricultural landscapes. However, few data are available on the effectiveness of this approach. The present study investigated the short-term effects of fencing to exclude livestock on dominant tree and shrub recruitment, plant species cover, litter and soil characteristics in remnant grassy woodlands in southern NSW. Vegetation and soil surveys were undertaken at 47 sites fenced by Greening Australia (NSW) for 2–4 years. Fenced and unfenced areas at each site were compared using split-plot sampling. Woodlands sampled were dominated by Yellow Box/Blakely's Red Gum ( Eucalyptus melliodora/Eucalyptus blakelyi ), Grey Box ( Eucalyptus microcarpa ) or White Cypress-pine ( Callitris glaucophylla ). Significantly higher numbers of tree recruits were found in the fenced sites, with tree recruitment found in 59% of fenced sites compared with 13% of unfenced sites. Fenced sites also had significantly greater cover of native perennial grasses, less cover of exotic annual species and less soil surface compaction. However, outcomes varied among woodland ecosystems and individual sites. Where tree recruitment occurred, there was significantly more tree recruitment where there was greater perennial grass cover and less regeneration where exotic annual grass cover or overstorey crown cover was dense. Few shrubs recruited in fenced or unfenced areas, reflecting the lack of mature shrubs in most sites. Fencing is an important first step for conserving threatened grassy woodlands, but more active management may be needed to enhance woodland recovery, particularly in sites where few or no recruits were found.
Key words bush regeneration, fencing, grazing exclusion, rehabilitation, woodland restoration.     

Long term effects of ART: What do animals tell us?

Early stages of mammalian embryonic development are now known to be very sensitive to their microenvironment, with long term effects on fetal, postnatal, and adult health, thus extending to these early stages the concept of Developmental Origin of Health and Disease (DoHaD). In this scientific context, and with 3% of births in developed countries, safety of Assisted Reproductive Techniques procedures becomes a matter of concern. Besides, embryo technologies in domestic mammals, using huge number of embryos, do not seem to evidence heavy impacts on adult phenotypes. This paper first discusses what can or cannot be concluded from farm animal data, then develops long term effects of ART procedures (ovarian stimulation, in vitro fertilization and embryo culture) evidenced in model species (mainly mouse model). Recent literature demonstrates both individual and cumulative effects of each ART procedure on fetal and postnatal phenotypes. In a second part, because they are sources for further perturbations, immediate effects of ART on early embryo phenotypes at the cellular and molecular levels are described in both farm animals and model species. Mechanistic hypotheses supporting these ART induced phenotypic alterations are subsequently considered. Finally, taking into account interspecies differences in the mechanisms likely to be involved, the relevance of results obtained in animal models for human ART are discussed.     

Does a long‐term shift in Wood Stork diet foreshadow adaptability to human‐induced rapid environmental change?

To preserve biodiversity, identifying at‐risk populations and developing conservation plans to mitigate the effects of human‐induced rapid environmental change (HIREC) are essential. Changes in diet, especially for food‐limited species, can aid in detecting populations being impacted by HIREC, and characterizing the quality, abundance, and temporal and spatial consistency of newly consumed food items may provide insight concerning the likelihood of a species persisting in a changing environment. We used Wood Storks (Mycteria americana) nesting in the Florida Everglades as a model system to study the possible effects of HIREC on a food‐limited population. We compared the diets of Wood Storks in 2013 and 2014 with those reported during the 1970s before major anthropogenic activities affected the Everglades system and prey availability. Wood Storks in our study consumed more large‐bodied sunfish species (Lepomis spp.), fewer native marsh fishes, and more non‐native fish species than during the 1970s. Large sunfish and non‐native fish are relatively rare in the drying pools of Everglades marshes where storks traditionally forage, suggesting that Wood Storks may be using novel foraging habitats such as created wetlands (i.e., canals and stormwater ponds). Although created wetlands have long hydroperiods conducive to maintaining large‐bodied fishes and could provide alternative foraging habitat when prey availability is reduced in natural marshes, additional studies are needed to determine the extent to which these wetlands are used by Wood Storks and, importantly, the quality of prey items potentially available to foraging Wood Storks in created wetlands.     

Why do some small islands lack vegetation? Evidence from long‐term introduction experiments

Classic island biogeography theory predicts that very small islands, near the extreme lower end of the species–area relationship, should support very few species. At times no species may be present, however, due to randomness in the immigration–extinction dynamics. Alternatively, a lack of vegetation on very small islands may indicate that such islands do not contain the appropriate habitat for the establishment or long‐term survival of plants, or that disturbances are too frequent or intense. These potential mechanisms were evaluated in the central Exumas, Bahamas, where surveys of 117 small islands revealed that over a third of the islands supported no terrestrial plant life. Area and exposure were significant predictors of whether a small island was vegetated or not in multiple logistic regressions. No islands naturally devoid of vegetation were colonized over a 17‐yr period, and only two naturally vegetated islands lost all vegetation. Experimental introductions of two species –Sesuvium portulacastrum and Borrichia arborescens– revealed that a number of islands naturally lacking vegetation were able to sustain introduced populations over the long term (up to 15 yr). Drought and hurricanes appeared to have reduced the establishment success and possibly long‐term survival of the introductions, although some populations survived four major hurricanes. Turnover rates of both introduced species were often an order of magnitude higher on the experimental introduction islands than on other islands in the archipelago. It appears many of the islands in this system that naturally lack vegetation may be physically capable of supporting terrestrial plant life, yet have no plants primarily due to barriers to colonization.     

Does host determine short‐range flight capacity of trichogrammatids?

Biological traits, such as body size, fecundity and fertility, of egg parasitoids are strongly influenced by host species, and the use of a single‐host species for consecutive generations has been showed to be detrimental for egg parasitoid biology. Besides biological traits, behaviour of egg parasitoids is also an important parameter for implying their performance in the field, but information about the effect of host on the behaviour of egg parasitoids is still scarce. Thus, this work aimed at determining the influence of host species on the short‐range flight capacity of three egg parasitoids Trichogrammatoidea annulata De Santis, Trichogramma atopovirilia Oatman and Platner and Trichogramma bruni Nagajara reared on Anagasta kuehniella (Zeller), Corcyra cephalonica (Stainton) and Sitotroga cerealella (Olivier), for first, 10 and 28 consecutive generations. Trichogrammatids emerged inside a tubular dark flight chamber, under controlled conditions, and short‐range flying response was based on the proportions of adults trapped to the sticky top of the chamber and the ones found on the bottom, which were checked for defective wings. Our data clearly demonstrate that trichogrammatid short‐range flight depends on the fasctidious host species. All three egg parasitoids had their flight capacity significantly reduced when emerged from S. cerealella. The highest flying capacity of T. annulata was registered when reared on C. cephalonica, while for T. atopovirilia was on A. kuehniella and T. bruni on both C. cephalonica and A. kuehniella. Parasitoid flight capacity is affected when reared on the same host over generations; however, it was not possible to define a pattern for any of the trichogrammatids. Our findings are of great relevance for quality control of mass‐reared egg parasitoids because measuring only behavioural traits with use of flight chambers can be more practical and less time‐consuming than assessing biological parameters.     

The evolutionary significance of parasitism: do parasite‐driven genetic dynamics occur ex silico?

It has long been recognized that reciprocal antagonism might lock host and parasite populations into a process of constant change, adapting and reacting in open‐ended coevolution. A significant body of theory supports this intuition: dynamic genetic polymorphisms are a common outcome of computer simulations of host–parasite coevolution. These in silico experiments have also shown that dynamical interactions could be responsible for high levels of genetic diversity in host populations, and even be the principle determinant of rates of genetic recombination and sexuality. The evolutionary significance of parasitism depends on the strength and prevalence of parasite‐mediated selection in nature. Here I appraise whether parasitism is a pervasive agent of evolutionary change by detailing empirical evidence for selection. Although there is considerable evidence of genetic variation for resistance, and hence the potential for selection, direct observation of parasite‐driven genetic change is lacking.     

Ecological and evolutionary consequences of size‐selective harvesting: how much do we know?

Size-selective harvesting, where the large individuals of a particular species are preferentially taken, is common in both marine and terrestrial habitats. Preferential removal of larger individuals of a species has been shown to have a negative effect on its demography, life history and ecology, and empirical studies are increasingly documenting such impacts. But determining whether the observed changes represent evolutionary response or phenotypic plasticity remains a challenge. In addition, the problem is not recognized in most management plans for fish and marine invertebrates that still mandate a minimum size restriction. We use examples from both aquatic and terrestrial habitats to illustrate some of the biological consequences of size-selective harvesting and discuss possible future directions of research as well as changes in management policy needed to mitigate its negative biological impacts.