Anssi Laurila

Uppsala University | UU · Department of Ecology and Genetics

It has become clear that the microbiome plays an important role in determining host health, diseases, and phenotypic variation. There is increasing evidence that the microbiome influences host fitness and its adaptation to the environment is changing our thinking on host-microbe interactions. However, it remains unclear how a host genotype shapes i...

Environmental stress is a major driver of ecological and evolutionary processes in nature. To cope with stress, organisms can adjust through phenotypic plasticity and/or adapt through genetic change. Here, we compared short-term behavioural (activity) and physiological (corticosterone levels, CORT) responses of Rana arvalis tadpoles from two diverg...

While both innate and adaptive immune system mechanisms have been implicated in resistance against the chytrid fungus Batrachochytrium dendrobatidis (Bd), studies on the role of specific MHC haplotypes on Bd infection are rare. Here, we studied variation in MHC Class IIB loci in the common toad Bufo bufo along a latitudinal gradient across Sweden....

Genetic variation is often lower at high latitudes, which may compromise the adaptability and hence survival of organisms. Here we show that genetic variability is negatively correlated with northern latitude in European green toads (Bufotes viridis). The result holds true for both putatively neutral microsatellite variation and supposedly adaptive...

Populations of the same species may differ in their sensitivity to pathogens but the factors behind this variation are poorly understood. Moreover, infections may cause sub-lethal fitness effects even in species resistant or tolerant to disease. The chytrid fungus Batrachochytrium dendrobatidis (Bd), is a generalist pathogen which has caused amphib...

Clinal variation is paramount for understanding the factors shaping genetic diversity in space and time. During the last glacial maximum, northern Europe was covered by glacial ice that rendered the region uninhabitable for most taxa. Different evolutionary processes during and after the recolonisation of this area from different glacial refugia ha...

Background: While there is evidence of both purifying and balancing selection in immune defense genes, large-scale genetic diversity in antimicrobial peptides (AMPs), an important part of the innate immune system released from dermal glands in the skin, has remained uninvestigated. Here we describe genetic diversity at three AMP loci (Temporin, Br...

Changes in phenology are among the most pervasive effects of current climate change. Modifications in the timing of life‐cycle events can affect the behavior, physiology and life‐history of wildlife. However, organisms can develop compensatory strategies in order to reduce the costs of phenological alterations. Here, we examine the extent and limit...

Genomic variation within and among populations is shaped by the interplay between natural selection and the effects of genetic drift and gene flow. Adaptive divergence can be found in small-scale natural systems even when population sizes are small, and the potential for gene flow is high, suggesting that local environments exert selection pressure...

The chytrid fungus Batrachochytrium dendrobatidis ( Bd ) has caused worldwide declines in amphibian populations. While Bd is widespread in southern and central Europe, its occurrence and distribution in northernmost Europe is mostly unknown. We surveyed for Bd in breeding anurans in Sweden by sampling 1917 amphibians from 101 localities and 3 regio...

Across latitudinal clines, the juvenile developmental rates of ectotherms often covary with the length of the growing season, due to life-history trade-offs imposed by the time-constrained environments. However, as the start of the growing season often varies substantially across years, adaptive parental effects on juvenile developmental rates may...

Amphibians are among the most threatened vertebrate taxa due to anthropogenic habitat change and emerging pathogens. The fungus Batrachochytrium dendrobatidis (Bd) may cause trade-offs between the immune responses and other important functions, such as mobility. The pool frog (Pelophylax lessonae) is red-listed in Sweden, and an earlier study cond...

Extreme climatic events, such as heat waves, may induce changes in nutrient acquisition by omnivorous ectotherms. Likely modulated by the intensity, frequency and duration of these events, dietary shifts during heat waves may threaten the stability of freshwaters. We investigated the effects of heat wave duration on diet assimilation and life-histo...

When environmental variation is spatially continuous, dispersing individuals move among nearby sites with similar habitat conditions. But as an environmental gradient becomes steeper, gene flow may connect more divergent habitats, and this is predicted to reduce the slope of the adaptive cline that evolves. We compared quantitative genetic divergen...

Stochastic effects from demographic processes and selection are expected to shape the distribution of genetic variation in spatially heterogeneous environments. As the amount of genetic variation is central for long‐term persistence of populations, understanding how these processes affect variation over large‐scale geographic gradients is pivotal....

Ectotherm development rates often show adaptive divergence along climatic gradients, but the genetic basis for this variation is rarely studied. Here, we investigated the genetic basis for phenotypic variation in larval development in the moor frog Rana arvalis from five regions along a latitudinal gradient from Germany to northern Sweden. We focus...

Human-induced changes of the environment, including landscape alteration and habitat loss, may affect wildlife disease dynamics and have important ramifications on wildlife conservation. Amphibians are among the vertebrate taxa most threatened by anthropogenic habitat change. The emerging fungal pathogen Batrachochytrium dendrobatidis (Bd) has caus...

While both innate and adaptive immune system mechanisms have been implicated in resistance against the chytrid fungus Batrachochytrium dendrobatitis, studies on the role of specific MHC haplotypes on Bd infection are rare. Here, we studied latitudinal variation in MHC Class IIB loci along a latitudinal gradient from southern to northern Sweden in c...

While adaptive divergence along environmental gradients has repeatedly been demonstrated, the role of postglacial colonization routes in determining phenotypic variation along gradients has received little attention. Here we used a hierarchical QST‐FST approach to separate the roles of adaptive and neutral processes in shaping phenotypic variation...

One of the worst threats facing wildlife populations worldwide is climate change. Average temperatures have risen globally and are expected to rise even further in the near future. Thus the climate is changing at an alarming rate and hence so are the living conditions of wildlife populations. The issue then becomes how will natural populations cope...

The fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a major threat to amphibian populations. To assist efforts to address such threats, we examined differences in Bd host infection prevalence among amphibian species and its relations to both local environmental factors in breeding habitats and landscape variables measured at three scales...

Summary table over data: Including detected presence of chytrid (Bd), number of infected individuals (Bd+), number of non-positive individuals (Bd-), Bd infection prevalence per site including all species (prev all), species sampled 2015 (Species 2015) and 2016 (Species 2016): Bb = Bufo bufo, Bob = Bombina bombina, Bv = Bufotes variabilis, Ec = Epi...

Results from the local and landscape models at three spatial scales and associations with detected Bd infection prevalence in the four-species Bayesian mixed-effects models. Mean (post.mean), lower (l-95% CI) and upper (u-95% CI) 95% confidence intervals, effective sample sizes (eff.samp) and p-values (pMCMC). Prevalence in Bombina bombina is the i...

Six species and differences in detected Bd infection prevalence. Bayesian mixed-effects models of Bd-prevalence and the six species of amphibians with prevalence in Bombina bombina as the intercept against which prevalence in the other species was tested. Mean (post.mean), lower (l-95% CI) and upper (u-95% CI) 95% confidence intervals, effective sa...

Rana temporaria occur across a large geographic and environmental gradient in Scandinavia. Several studies involving common garden experiments have established adaptive divergence across the gradient. The main objective of this study was to determine the extent of neutral and adaptive genetic divergence across the latitudinal gradient. Here we sequ...

This PDF file includes: Materials and Methods - Figs. S1, S3, S4, S6, S7, and S9 to S16 - Tables S2 to S5 - Captions for figs. S2, S5, and S8 - Caption for table S1 - Captions for data S1 to S3 - References

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is a major threat to amphibian populations. Here we asked if the prevalence of Bd differs between amphibian species and whether it is related to local environmental factors in breeding habitats as well as landscape variables measured at three scales (500, 2000 and 5000 m radius) in southernmos...

Fast‐growing genotypes living in time‐constrained environments are often more prone to predation, suggesting that growth‐predation risk trade‐offs are important factors maintaining variation in growth along climatic gradients. However, the mechanisms underlying how fast growth increases predation‐mediated mortality are not well understood. Here, we...

Parasitic chytrid fungi have emerged as a signifcant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modifed a pre-existing protocol for isolating chytrids f...

Panzootic chytrid fungus out of Asia Species in the fungal genus Batrachochytrium are responsible for severe declines in the populations of amphibians globally. The sources of these pathogens have been uncertain. O'Hanlon et al. used genomics on a panel of more than 200 isolates to trace the source of the frog pathogen B. dendrobatidis to a hyperdi...

MHC genes are key components in disease resistance and an excellent system for studying selection acting on genetic variation in natural populations. Current patterns of variation in MHC genes are likely to be influenced by past and ongoing selection as well as demographic fluctuations in population size such as those imposed by post-glacial recolo...

Parasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into sterile culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating...

Background Past events like fluctuations in population size and post-glacial colonization processes may influence the relative importance of genetic drift, migration and selection when determining the present day patterns of genetic variation. We disentangle how drift, selection and migration shape neutral and adaptive genetic variation in 12 moor...

In the Mediterranean basin, the globally increasing temperatures are expected to be accompanied by longer heat waves. Commonly assumed to benefit cold-limited invasive alien species, these climatic changes may also change their feeding preferences, especially in the case of omnivorous ectotherms. We investigated heat wave effects on diet choice, gr...

Data set of the juvenile Procambarus clarkii. Biometrics and isotope data. (PDF)

Data set of the adult Procambarus clarkii. Biometrics and isotope data. (PDF)

Organisms are exposed to multiple sources of stress in nature. When confronted with a stressful period affecting growth and development, compensatory responses allow the restoration of individual fitness, providing an important buffering mechanism against climatic and other environmental variability. However, trade-offs between increased growth/dev...

Extrinsic mortality has a strong impact on the evolution of life-histories, prey morphology and behavioural adaptations, but for many animals the causes of mortality are poorly understood. Predation is an important driver of extrinsic mortality and mobile animals form groups in response to increased predation risk. Furthermore, in many species juve...

Thermal adaptation theory predicts that thermal specialists evolve in environments with low temporal and high spatial thermal variation, whereas thermal generalists are favored in environments with high temporal and low spatial variation. The thermal environment of many organisms is predicted to change with globally increasing temperatures and ther...

Organisms living in temperate environments, with only a short time window for growth and reproduction, often develop compensatory responses after experiencing a period of adverse conditions. Parents can also affect growth and development trajectories of their offspring in order to provide them with better chances to survive. In our study, we delaye...

1.In seasonal environments, modifications in the phenology of life-history events can alter the strength of time-constraints experienced by organisms. Offspring can compensate for a change in timing of hatching by modifying their growth and development trajectories. However, intra- and inter -specific interactions may affect these compensatory resp...

Temperature can play an important role in determining the feeding preferences of ectotherms. In light of the warmer temperatures arising with the current climatic changes omnivorous ectotherms may perform diet shifts towards higher herbivory to optimize energetic intake. Such diet shifts may also occur during heat waves, which are projected to beco...

As organisms living in temperate environments often have only a short time window for growth and reproduction, their life-history strategies are expected to be influenced by these time-constraints. Parents may alter the pace of offspring life-history as a response to changes in breeding phenology. However, the responses to changes in time-constrain...

When similar selection acts on the same traits in multiple species or populations, parallel evolution can result in similar phenotypic changes, yet the underlying molecular architecture of parallel phenotypic divergence can be variable. Maternal effects can influence evolution at ecological time scales and facilitate local adaptation, but their con...

Experiments using natural populations have provided mixed support for thermal adaptation models, probably because the conditions are often confounded with additional environmental factors like seasonality. The contrasting geothermal environments within Lake Mývatn, northern Iceland, provide a unique opportunity to evaluate thermal adaptation models...

Temperature is one of the most influential forces of natural selection impacting all biological levels. In the face of increasing global temperatures, studies over small geographical scales allowing investigations on the effects of gene flow are of great value for understanding thermal adaptation. Here we investigated genetic population structure i...

Many organisms show predator-induced behavioural and morphological phenotypic plasticity. These defence mechanisms are often expressed simultaneously. To estimate the relative importance of these two defences, we conducted a laboratory experiment using tadpoles of the common frog (Rana temporaria) as prey and Aeshna dragonfly larvae as predators. W...

Accurate predictions regarding how climate change affects species and populations are crucial for the development of effective conservation measures. However, models forecasting the impact of climate change on natural environments do not often consider the geographic variation of an organism's life history. We examined variation in developmental pl...

Figure S1. Temperature characteristics of the study areas (see main text for details). Table S1. Mixed models ANOVAS and univariate general linear models for life‐history traits. Table S2. Univariate general linear models for temperature variables.

Ion channels and pumps are responsible for ion flux in cells, and are key mechanisms mediating cellular function. Many environmental stressors, such as salinity and acidification, are known to severely disrupt ionic balance of organisms thereby challenging fitness of natural populations. Although ion channels can have several vital functions during...

While temperature variation is known to cause large-scale adaptive divergence, its potential role as a selective factor over microgeographic scales is less well understood. Here, we investigated how variation in breeding pond temperature affects divergence in multiple physiological (thermal performance curve (TPC) and critical thermal maximum (CTma...

Environmental stress, such as acidification, can challenge persistence of natural populations and act as a powerful evolutionary force at ecological time scales. The ecological and evolutionary responses of natural populations to environmental stress at early life-stages are often mediated via maternal effects. During early life-stages, maternal ef...

The timing of seasonal life-history events is assumed to evolve to synchronize life cycles with the availability of resources. Temporal variation in breeding time can have severe fitness consequences for the offspring, but the interplay between adult reproductive decisions and offspring phenotypes remains poorly understood. Transgenerational plasti...

The way environmental variation shapes neutral and adaptive genetic variation in natural populations is a key issue in evolutionary biology. Genome scans allow the identification of the genetic basis of local adaptation without previous knowledge of genetic variation or traits under selection. Candidate loci for divergent adaptation are expected to...

Invasive alien predators can impose strong selection on native prey populations and induce rapid evolutionary change in the invaded communities. However, studies on evolutionary responses to invasive predators are often complicated by the lack of replicate populations differing in coexistence time with the predator, which would allow determining ho...

Predator-induced phenotypic plasticity has been widely documented in response to native predators, but studies examining the extent to which prey can respond to exotic invasive predators are scarce. As native prey often do not share a long evolutionary history with invasive predators, they may lack defenses against them. This can lead to population...

Location and detailed explanation of the 20 landmarks digitized for estimating tadpole body shape.

Environmental change can simultaneously cause abiotic stress and alter biological communities, yet adaptation of natural populations to co-changing environmental factors is poorly understood. We studied adaptation to acid and predator stress in six moor frog (Rana arvalis) populations along an acidification gradient, where abundance of invertebrate...

Background / Purpose: Our previous work had revealed that tadpoles are able to compensate for a delay in hatching by shortening their larval period (1). In our study system, moor frogs (Rana arvalis) living in central Sweden, breeding occurs as soon as ponds thaw in early spring which carries the potential cost of freezing for recently laid clutc...

Organisms normally grow at a sub-maximal rate. After experiencing a period of arrested growth, individuals often show compensatory growth responses by modifying their life-history, behaviour and physiology. However, the strength of compensatory responses may vary across broad geographic scales as populations differ in their exposition to varying ti...