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Consequences of population structure for sex allocation and sexual conflict

Both sex allocation and sexual conflict can be modulated by spatial structure. However, how the interplay between the type of dispersal and the scale of competition simultaneously affects these traits in sub-divided populations is rarely considered. We investigated sex allocation and sexual conflict evolution in meta-populations of the spider mite Tetranychus urticae evolving under budding (pairing females from the same patch) or random (pairing females from different patches) dispersal and either local (fixed sampling from each subpopulation) or global (sampling as a function of subpopulation productivity) competition. Females evolving under budding dispersal produced less female-biased offspring sex ratios than those from the random dispersal selection regimes, contradicting theoretical predictions. In contrast, the scale of competition did not strongly affect sex allocation. Offspring sex ratio and female fecundity were unaffected by the number of mates, but female fecundity was highest when their mates evolved under budding dispersal, suggesting these males inflict less harm than those evolving under random dispersal. This work highlights that population structure can impact the evolution of sex allocation and sexual conflict. Moreover, selection on either trait may reciprocally affect the evolution of the other, for example via effects on fecundity.

Seasonal niche tracking of climate emerges at the population level in a migratory bird

Seasonal animal migration is a widespread phenomenon. At the species level, it has been shown that many migratory animal species track similar climatic conditions throughout the year. However, it remains unclear whether such niche tracking pattern is a direct consequence of individual behaviour or emerges at the population or species level through behavioural variability. Here, we estimated seasonal niche overlap and seasonal niche tracking at the individual and population level of Central European White Storks (Ciconia ciconia). We quantified niche tracking for both weather and climate conditions to control for the different spatio-temporal scales over which ecological processes may operate. Our results indicate that niche tracking is a bottom-up process. Individuals mainly track weather conditions while climatic niche tracking mainly emerges at the population level. This result may be partially explained by a high degree of intra- and inter-individual variation in niche overlap between seasons. Understanding how migratory individuals, populations and species respond to seasonal environments is key for anticipating the impacts of global environmental changes.

opencc-zeroDec 2019View details →

Population studies of the wild tomato species Solanum chilense reveal geographically structured major gene-mediated pathogen resistance

Natural plant populations encounter strong pathogen pressure and defense-associated genes are known to be under selection dependent on the pressure by the pathogens. Here we use populations of the wild tomato Solanum chilense to investigate natural resistance against Cladosporium fulvum, a well-known ascomycete pathogen of domesticated tomatoes. Host populations used are from distinct geographical origins and share a defined evolutionary history. We show that distinct populations of S. chilense differ in resistance against the pathogen. Screening for major resistance gene mediated pathogen recognition throughout the whole species showed clear geographical differences between populations and complete loss of pathogen recognition in the south of the species range. In addition, we observed high complexity in a homologues of Cladosporium resistance (Hcr) locus, underlying the recognition of C. fulvum, in central and northern populations. Our findings show that major gene mediated recognition specificity is diverse in a natural plant-pathosystem. We place major gene resistance in a geographical context that also defined the evolutionary history of that species. Data suggest that the underlying loci are more complex than previously anticipated, with small-scale gene recombination being possibly responsible for maintaining balanced polymorphisms in the populations that experience pathogen pressure.

Captive-bred populations of a partially migratory salmonid fish are unlikely to maintain migratory polymorphism in natural habitats

Supplementation of wild populations with captive-bred individuals is often ineffective for boosting long-term productivity of wild populations. On the other hand, it remains unknown whether supplementation can act to maintain life-history variation in natural habitats, which is also important for the long-term persistence of populations and species. Partial migration, in which both migratory and resident individuals are maintained in a population, is commonly found across animal taxa. However, human-induced habitat fragmentation continues to cause rapid decline in a migratory phenotype among many natural populations. By using field and hatchery experiments, we here demonstrated that while migrants and residents could be maintained in captive environments, few fish became migrants in natural streams in red-spotted masu salmon Oncorhynchus masou ishikawae. Released captive-bred fish rarely reached the threshold body size necessary to become migrants in natural streams, presumably due to lower growth condition in natural than in captive environments. The decision to migrate is often considered a threshold trait in salmonids and other animal taxa. Our findings highlight the need for supplementation programs to acknowledge environmentally induced changes in life-history decisions for partially migratory species.

Contrasting responses to climate change at Himalayan treelines revealed by population demographics of two dominant species

<ol> <li>Alpine treelines are expected to shift upward due to recent climate change. However, interpretation of changes in montane systems has been problematic because effects of climate change are frequently confounded with those of land use changes. The eastern Himalaya, particularly Langtang National Park, Central Nepal, has been relatively undisturbed for centuries and thus presents an opportunity for studying climate change impacts on alpine treeline uncontaminated by potential confounding factors.</li> <li>We studied two dominant species, Abies spectabilis and Rhododendron campanulatum, above and below the treeline on two mountains. We constructed 13 transects, each spanning up to 400m in elevation, in which we recorded height and state (dead or alive) of all trees, as well as slope, aspect, canopy density, and measures of anthropogenic and animal disturbance. In a subset of individuals, we determined the age of the plants with tree rings.</li> <li>All size classes of R. campanulatum plants had lower mortality above treeline than below it, and young R. campanulatum plants (<2m tall) were at higher density above treeline than below. A. spectabilis shows little evidence of a position change from the historic treeline, with a sudden extreme drop in density above treeline compared to below. Recruitment, as measured by size class distribution, was greater above treeline than below for both species but A. spectabilis is confined to ~25m above treeline whereas R. campanulatum is luxuriantly growing up to 200m above treeline. </li> <li> Synthesis. Evidence suggests that the elevational limits of R. campanulatum have shifted upward both because (1) young R. campanulatum plants above treeline benefited from facilitation of recruitment by surrounding vegetation, allowing upward expansion of recruitment, and (2) increased adult survival due to a general temperature amelioration to mature plants. We predict that the current pure stand of R. campanulatum growing above treeline will be colonized by A. spectabilis that will, in turn, outshade and eventually relegate R. campanulatum to be a minor component of the community, as is the current situation below the treeline. </li> </ol>

Testing for population differences in evolutionary responses to pesticide pollution in brown trout (Salmo trutta)

Pesticides are often toxic to non-target organisms, especially to those living in rivers that drain agricultural land. The brown trout (Salmo trutta) is a keystone species in many such rivers, and natural populations have hence been chronically exposed to pesticides over multiple generations. The introduction of pesticides decades ago could have induced evolutionary responses within these populations. Such a response would be predicted to reduce the toxicity over time but also deplete any additive genetic variance for the tolerance to the pesticides. If so, populations are now expected to differ in their susceptibility and in the variance for the tolerance depending on the pesticides they have been exposed to. We sampled breeders from seven natural populations that differ in their habitats and that show significant genetic differentiation. We stripped them for their gametes and produced 118 families by in vitro fertilization. We then raised 20 embryos per family singly in experimentally controlled conditions and exposed them to one of two ecologically relevant concentrations of either the herbicide S-metolachlor or the insecticide diazinon. Both pesticides affected embryo and larval development at all concentrations. We found no statistically significant additive genetic variance for tolerance to these stressors within or between populations. Tolerance to the pesticides could also not be linked to variation in carotenoid content of the eggs. However, pesticide tolerance was linked to egg size, with smaller eggs being more tolerant to the pesticides than larger eggs. We conclude that an evolutionary response to these pesticides is currently unlikely, and that (i) continuous selection in the past has either depleted genetic variance in all the populations we studied, or (ii) that exposure to the pesticides never induced an evolutionary response. The observed toxicity selects against large eggs that are typically spawned by larger and older females.

Virus infections in 27 Plantago lanceolata populations in the Åland Islands in 2015

<ul> <li>Human alteration of natural habitats may change the processes governing species interactions in wild communities. Wild populations are increasingly impacted by agricultural intensification, yet it is unknown whether this alters biodiversity mediation of disease dynamics.</li> <li>We investigated the association between plant diversity (species richness, diversity) and infection risk (virus richness, prevalence) in populations of Plantago lanceolata in natural landscapes as well as those occurring at the edges of cultivated fields. Altogether 27 P. lanceolata populations were surveyed for population characteristics and sampled for PCR detection of five recently characterized viruses.</li> <li>We find that plant species richness and diversity correlated negatively with virus infection prevalence. Virus species richness declined with increasing plant diversity and richness in natural populations while in agricultural edge populations' species richness was moderately higher, and not associated with plant richness. This difference was not explained by changes in host richness between these two habitats, suggesting potential pathogen spill-over and increased transmission of viruses across the agro-ecological interface. Host population connectivity significantly decreased virus infection prevalence.</li> <li>We conclude that human use of landscapes may change the ecological laws by which natural communities are formed with far reaching implications for ecosystem functioning and disease.</li> </ul>

opencc-by-4.0Dec 2020View details →

Homozygosity mapping reveals population history and trait architecture in self- incompatible pear (Pyrus spp.)

opencc-by-4.0Dec 2020View details →

Homozygosity mapping reveals population history and trait architecture in self- incompatible pear (Pyrus spp.)

Runs of homozygosity (ROH) are successive homozygous segments of the genome where the two haplotypes inherited from the parents are identical-by-descent. A key focus of this project is to investigate ROH distribution patterns in the genomes of outbred fruit crops using pear as a study caseRuns of homozygosity (ROH) are successive homozygous segments of the genome where the two haplotypes inherited from the parents are identical-by-descent. A key focus of this project is to investigate ROH distribution patterns in the genomes of outbred fruit crops using pear as a study case

opencc-by-4.0Dec 2020View details →

Homozygosity mapping reveals population history and trait architecture in self- incompatible pear (Pyrus spp.)

Ecology directs host-parasite coevolutionary trajectories across Daphnia-microparasite populations

Host-parasite interactions often fuel coevolutionary change. However, parasitism is one of a myriad of possible ecological interactions in nature. Biotic (e.g., predation) and abiotic (e.g., temperature) variation can amplify or dilute parasitism as a selective force on hosts and parasites, driving population variation in (co)evolutionary trajectories. We dissected the relationships between wider ecology and coevolutionary trajectory using 16 ecologically complex Daphnia magna-Pasteuria ramosa ponds seeded with an identical starting host (Daphnia) and parasite (Pasteuria) population. We show, using a time-shift experiment and outdoor population data, how multivariate biotic and abiotic ecological differences between ponds caused coevolutionary divergence. Wider ecology drove variation in host evolution of resistance, but not parasite infectivity; parasites subsequently coevolved in response to the changing complement of host genotypes, such that parasites adapted to historically resistant host genotypes. Parasitism was a stronger interaction for the parasite than for its host, likely because the host is the principal environment and selective force, whereas for hosts, parasite-mediated selection is one of many sources of selection. Our findings reveal the mechanisms through which wider ecology creates coevolutionary hotspots and coldspots in biologically realistic arenas of host-parasite interaction, and sheds light on how the ecological theatre can affect the (co)evolutionary play.

The demographic contributions of connectivity versus local dynamics to population growth of an endangered bird

1. Conservation and management increasingly focus on connectivity, because connectivity driven by variation in immigration rates across landscapes is thought to be crucial for maintaining local population and metapopulation persistence. Yet, efforts to quantify the relative role of immigration on population growth across the entire range of species and over time have been lacking. 2. We assessed whether immigration limited local and range-wide population growth of the endangered snail kite (Rostrhamus sociabilis) in Florida, USA, over 18 years using multi-state, reverse-time modeling that accounts for imperfect detection of individuals and unobservable states. Demographic contributions of immigration varied depending on the dynamics and geographic position of the local populations, were scale-dependent, and changed over time. 3. By comparing the relative contributions of immigration versus local demography for periods of significant change in local abundance, we found empirical evidence for a disproportionately large role of immigration in facilitating population growth of a centrally-located population—a connectivity 'hub'. The importance of connectivity changed depending of the spatial scale considered, such that immigration was more important driver of population growth at small versus large spatial scales. Furthermore, the contribution of immigration was much greater during time periods when local population size was small, emphasizing abundance-dependent rescue effects. 4. Our findings suggest that efforts aimed at improving local breeding habitat will likely be most effective at increasing snail kite population growth. More broadly, our results provide much needed information on the role of connectivity for population growth, suggesting that connectivity conservation may have the greatest benefits when efforts focus on centrally located habitat patches and small populations. Furthermore, our results highlight that connectivity is highly dynamic over time and that interpreting the effects of connectivity at local scales may not transfer to region-wide dynamics.

opencc-zeroDec 2019View details →

Fitness maps to a large-effect locus in introduced stickleback populations

Mutations of small effect underlie most adaptation to new environments, but beneficial variants with large fitness effects are expected to contribute under certain conditions. Genes and genomic regions having large effects on phenotypic differences between populations are known from numerous taxa, but fitness effect sizes have rarely been estimated. We mapped fitness over a generation in an F2 intercross between a marine and a lake stickleback population introduced to a freshwater pond. A QTL map of the number of surviving offspring per F2 female detected a single, large-effect locus near Ectodysplasin (Eda), a gene having an ancient freshwater allele causing reduced bony armor and other changes. F2 females homozygous for the freshwater allele had twice the number of surviving offspring as homozygotes for the marine allele, producing a large selection coefficient, s = 0.50 ± 0.09 SE. Correspondingly, the frequency of the freshwater allele increased from 0.50 in F2 mothers to 0.58 in surviving offspring. We compare these results to observed allele frequency changes at the Eda gene in an Alaskan lake population colonized by marine stickleback in the 1980's. The frequency of the freshwater Eda allele rose steadily over multiple generations and reached 95% within 20 years, yielding a similar estimate of selection, s = 0.49 ± 0.05. These findings are consistent with other studies suggesting strong selection on this gene (and/or linked genes) in fresh water. Selection on ancient genetic variants carried by colonizing ancestors is likely to increase the prevalence of large-effect fitness variants in adaptive evolution.

Signatures of local adaptation to climate in natural populations of sweet chestnut (Castanea sativa Mill.) from southern Europe

Context: Temperate forest species, such as chestnut (Castanea sativa Mill.), are currently threatened by increasing temperature together with disruption and reduction of precipitation due to climate change. In this context, understanding the adaptation processes of species will help to manage and ensure the conservation of forests. Aims: We studied the relationship between genetic variability and climate variables in natural populations of C. sativa using a landscape genomics approach aimed to identify local adaption processes. Methods: Using five genomic SSRs and eight functional EST-SSRs markers, 268 individuals belonging to ten different natural European chestnut populations distributed in contrasting climatic sites were genotyped. In addition, associations between allelic variation and climatic variables (environmental association analyses approach) were performed using Samada and LFMM. Results: Results highlighted a strong inter-relationship between climate variables and evolutionary processes resulting in adaptive variation. STRUCTURE analysis based on functional markers split the populations in three separate gene pools (K=3), mostly in agreement with the different climatic conditions existing in the studied areas. Divergent spatial patterns of genetic variation between rainy and arid areas were found. We detected a total of 202 associations with climate among 22 different alleles, 9% of which related with the outlier locus FIR059, known to be implicated in regulatory mechanisms during water stress adaptation processes. Conclusions: Landscape genomics analyses revealed a pattern of adaptive variation, where specific climatic variables influenced the frequencies distribution and fixation of several alleles, resulting in local adaptation processes of the populations in the investigated areas. Our findings underline the close inter-relationship existing between climate and genetic variability, and indicate how this approach could provide valuable information for the management of forest species in a rapidly changing environment.

The genetic basis of coordinated plasticity across functional units in a Lake Malawi cichlid mapping population

Adaptive radiations are often stereotypical, as populations repeatedly specialize along conserved environmental axes. Phenotypic plasticity may be similarly stereotypical, as individuals respond to environmental cues. These parallel patterns of variation, which are often consistent across traits, have led researchers to propose that plasticity can facilitate predictable patterns of evolution along environmental gradients. This "flexible stem" model of evolution raises questions about the genetic nature of plasticity, including: How complex is the genetic basis for plasticity? Is plasticity across traits mediated by many distinct loci, or few "global" regulators? To address these questions, we reared a hybrid cichlid mapping population on alternate diet regimes mimicking an important environmental axis. We show that plasticity across an array of ecologically relevant traits is generally morphologically integrated, such that traits respond in a coordinated manner, especially those with overlapping function. Our genetic data are more ambiguous. While our mapping experiment provides little evidence for global genetic regulators of plasticity, these data do contain a genetic signal for the integration of plasticity across traits. Overall, our data suggest a compromise between genetic modularity, whereby plasticity may evolve independently across traits, and low-level but widespread genetic integration, establishing the potential for plasticity to experience coordinated evolution.

Influence of Quaternary environmental changes on mole populations inferred from mitochondrial sequences and evolutionary rate estimation

Quaternary environmental changes fundamentally influenced genetic diversity of the temperate-zone terrestrial animals, including those on the Japanese Archipelago. The genetic diversity of present-day populations are taxon and region specific, but its determinants are poorly understood. Here, we analyzed cytochrome b gene (Cytb) sequences (1,140 bp) of mitochondrial DNA (mtDNA) to elucidate factors determining the genetic variation in three species of large moles: Mogera imaizumii and Mogera wogura occur in Northern and Southern mainland Japan (Honshu, Shikoku, and Kyushu), and Mogera robusta occurs on the nearby Asian continent. Network construction with the Cytb sequences revealed 10 star-shaped clusters with apparent geographic affinity. Mismatch distribution analysis showed that modes of pairwise nucleotide differences (t values) were grouped into five classes in terms of the level, implying the occurrence of five stages for the rapid expansion. It is conceivable that a severe cold periods and a subsequent warm periods during the late Quaternary are responsible for the population expansion events. The first and third oldest events include island-derived haplotypes, indicative of involvement of land bridge formation between remote islands, hence suggesting association of the ends of the penultimate (PGM, ca. 130,000 years ago) and last (LGM, ca. 15,000 years ago) glacial maxima, respectively. Since the third one is followed by the fourth one, it is plausible that the termination of Younger Dryas and subsequent abrupt warming at ca. 11,500 years ago facilitated the fourth expansion event. The second is most likely corresponding to the early marine isotope stage (MIS) 3 (ca. 53,000 years ago) when the glaciation and subsequent warming period are predicted to have influenced biodiversity. Utilization of the critical times of 130,000, 53,000, 15,000, and 11,500, years ago as calibration points yielded evolutionary rates of 0.03, 0.045, 0.10 and 0.10 substitutions/site/million years, respectively, showing the time-dependent manner whose pattern is similar to that seen in small rodents reported in our previous studies. The age of the fifth expansion event was calculated to be 5,800 years ago with the rate of 0.10 substitutions/site/million years ago, during the mid-Holocene, suggestive of influence of humans or other unspecified reason, such as the Jomon marine transgression.

opencc-zeroDec 2019View details →

Predation risk shapes the degree of placentation in natural populations of live-bearing fish

The placenta is a complex life-history trait that is ubiquitous across the tree of life. Theory proposes that the placenta evolves in response to high performance-demanding conditions by shifting maternal investment from pre- to post-fertilization, thereby reducing a female's reproductive burden during pregnancy. We test this hypothesis by studying populations of the fish species Poeciliopsis retropinna in Costa Rica. We found substantial variation in the degree of placentation among natural populations associated with predation risk: females from high predation populations had significantly higher degrees of placentation compared to low predation females, while number, size and quality of offspring at birth remained unaffected. Moreover, a higher degree of placentation correlated with a lower reproductive burden and hence likely an improved swimming performance during pregnancy. Our study advances an adaptive explanation for why the placenta evolves by arguing that an increased degree of placentation offers a selective advantage in high predation environments.

opencc-byJan 2021View details →

Previst project; a Swiss campaing within the general population for crime prevention in sex work

In this link, we share private pictures and videos from the campaign "We don't buy a body but a service, part of a crime prevention program in the canton of Vaud (Switzerland). The campaign aimed to prevent antisocial behaviour towards prostitutes by encouraging population's more realistic view of the sex work and by minimising the excuses for crime -the neutralisation techniques as defined by Sykes & Matza (1957). With the slogan “we don’t buy a body but a service”, we installed a panel in the prostitution neighbourhood in Lausanne (the capital of the canton of Vaud). We also organised four artistic performances in the city centre and we advertised the campaign through interviews with the media. Although the impact of this campaign on the behaviour of the population is difficult to assess, we estimated that the number of local citizens reached is non- negligible. We suggest that sex workers should be encouraged to participate in further campaigns towards the general population as well as the academia should collaborate with practitioners for evaluating the impact of such projects.

opencc-zeroJan 2021View details →

Data from: Genomic variation, population history and within-archipelago adaptation between island bird populations

Oceanic island archipelagos provide excellent models to understand evolutionary processes. Colonisation events and gene flow can interact with selection to shape genetic variation at different spatial scales. Landscape-scale variation in biotic and abiotic factors may drive fine-scale selection within islands, while long-term evolutionary processes may drive divergence between distantly related populations. Here, we examine patterns of population history and selection between recently diverged populations of the Berthelot's pipit (Anthus berthelotii), a passerine endemic to three North Atlantic archipelagos. First we use demographic trees and f3 statistics to show that genome-wide divergence across the species range is largely shaped by colonisation and bottlenecks, with evidence of very weak gene flow between populations. Then, using a genome scan approach, we identify signatures of divergent selection within-archipelagos at SNPs in genes potentially associated with craniofacial development and DNA repair. We did not detect within-archipelago selection at the same SNPs as were detected previously at broader spatial scales between archipelagos, but did identify signatures of selection at loci associated with similar biological functions. These findings suggest that similar ecological factors may repeatedly drive selection between recently separated populations, as well as at broad spatial scales across varied landscapes.