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opencc-zeroAug 2020View details →

Age-dependent phenological plasticity in a wild bird

Life-history traits are often plastic in response to environmental factors such as temperature or precipitation, and they also vary with age in many species. Trait variation during the lifetime could thus be partly driven by age-dependent plasticity in these traits. We study whether plasticity of a phenological trait – the egg-laying date – with respect to spring temperature, varies with age, and explore whether this variation relates to changes in breeding success throughout the life cycle. We use data from a four-decade long-term monitoring of a wild population of blue tits in Corsica to estimate age-dependent plasticity of reproductive phenology and annual reproductive success. We show that both laying date plasticity and annual reproductive success vary with age: young and old females are less plastic, and fledge fewer offspring, than middle-age females. Furthermore, in contrast to young and prime-age females, in old females fledging success does not depend on laying date. 5. Phenological plasticity is a major mechanism for coping with rapid environmental variation. Our results suggest that understanding its role in adaptation to climate change and population persistence requires integrating the age structure of the population.

zenodo28/100

Plastics: "I'm Gonna Live Forever" - No.

Plastic pollution is a major, pressing, global concern. Every year, coastal nations dispose 8 million tons of plastic waste into the oceans. This figure equates to setting five rubbish bags full of trash on every foot of coastline around the world. Millions of animals are killed and sickened by plastics every year, from birds to fish and other marine organisms. Plastic residues are found in nearly all species of seabirds. To address this global catastrophe, alternatives to fossil fuel-derived plastics must be developed and made cheaper and more accessible to all. There is a possibility that using plant-derived polysaccharides such as starch and pectin, and seaweed-derived carrageenan in food packaging might work after processing them into films. One inspiration for this is the food packaging made from seaweed, a concept that started in Indonesia. Plant-derived polysaccharides turned into food packaging can also be halal-certified, safe to eat, and nutritious, containing high fibre and nutrients. In addition, they are biodegradable, addressing the issue of plastics enroaching our most fragile ecosystems. These plant-derived films can also be turned into collagen for medical uses. One of the aims of this project is to devise, develop, and optimise environmentally safe and facile methods of producing edible and biodegradable food packaging material and collagen for medical uses from starch, pectin, and other plant-based polysaccharides derived from food wastes, and analyse their bio/physical properties.

opencc-by-4.0Aug 2020View details →

opencc-zeroAug 2020View details →

Decoupling the effects of food and density on life history plasticity of wild animals using field experiments: Insights from the steward who sits in the shadow of its tail, the North American red squirrel

Long-term studies of wild animals provide the opportunity to investigate how phenotypic plasticity is used to cope with environmental fluctuations, and how the relationships between phenotypes and fitness can be dependent upon the ecological context. Most previous studies have only investigated life history plasticity in response to changes in temperature, yet wild animals often experience multiple environmental fluctuations simultaneously. This requires field experiments to decouple which ecological factor induces plasticity in fitness-relevant traits to better understand their population-level responses to those environmental fluctuations. For the past 32 years, we have conducted a long-term integrative study of individually marked North American red squirrels (Tamiasciurus hudsonicus Erxleben) in the Yukon, Canada. We have used multi-year field experiments to examine the physiological and life history responses of individual red squirrels to fluctuations in food abundance and conspecific density. Our long-term observational study and field experiments show that squirrels can anticipate increases in food availability and density, thereby decoupling the usual pattern where animals respond to, rather than anticipate, an ecological change. As in many other study systems, ecological factors that can induce plasticity (such as food and density) co-vary. However, our field experiments that manipulate food availability and social cues of density (frequency of territorial vocalizations) indicate that increases in social (acoustic) cues of density in the absence of additional food can induce similar life history plasticity, as does experimental food supplementation. Changes in the levels of metabolic hormones (glucocorticoids) in response to variation in food and density are one mechanism that seems to induce this adaptive life history plasticity. Although we have not yet investigated the energetic response of squirrels to elevated density or its association with life history plasticity, energetics research in red squirrels has overturned several standard pillars of knowledge in physiological ecology. We show how a tractable model species combined with integrative studies can reveal how animals cope with resource fluctuations through life history plasticity.

opencc-zeroSep 2020View details →

Species responses to changing precipitation depends on trait plasticity rather than trait means and intraspecific variation

1. Trait-based approaches are key to develop mechanistic understanding of differences in plant species performance under environmental change. While mean trait values have been widely used to link functional traits to species performance, the contribution of intraspecific trait variation and trait plasticity remains unclear. Moreover, environmentally induced changes in species biomass is caused by changes in the number of individuals and individual growth rate, both of which should be influenced by trait differences and plasticity. Our goal in this study is to use trait-based information to explain species performance via changes in species abundance and individual weight. 2. We measured the mean, intraspecific variation and plasticity of nine aboveground plant traits, and a further three mean root traits of ten common species in a precipitation manipulation experiment in semiarid grassland. We used this trait information to explain differences in the responses of species biomass, abundance and mean individual weight to changing precipitation. Species responses were calculated as the normalized slopes of the regressions between species biomass, abundance and individual weight with the manipulated precipitation amount. 3. We found strong differences in species responses to changing precipitation for species biomass, abundance and mean individual weight. Reduced precipitation decreased biomass, abundance and mean individual weight for some species, but increased them for others. Biomass and mean individual weight of species with resource-acquisitive traits, such as shallow rooted species, showed stronger positive responses to changing precipitation compared to resource-conservative traits, like those with deep roots. For aboveground traits, trait plasticity was the strongest predictor of species responses compared to mean traits and intraspecific trait variation. In addition, trait plasticity regulated changes in species biomass more via changes in species abundance than mean individual weight. 4. These results indicate that trait plasticity is a key driver for determining species specific responses to changing precipitation and needs more consideration for understanding and predicting ecosystem structure and functioning in future climate scenarios.

opencc-zeroSep 2020View details →

Data from: High content imaging of unbiased chemical perturbations reveals that the phenotypic plasticity of the actin cytoskeleton is constrained

Although F-actin has a large number of binding partners and regulators, the number of phenotypic states available to the actin cytoskeleton is unknown. Here, we quantified 74 features defining F-actin and cellular morphology in >25 million cells after treatment with a library of 114,400 structurally diverse compounds. After reducing the dimensionality of these data, we found that only ~25 recurrent F-actin phenotypes emerged, each defined by distinct quantitative features that could be machine learned. We identified 2003 unknown compounds as inducers of actin-related phenotypes, including two that directly bind talin, a core regulator of integrin activity. Moreover, we observed that compounds with distinct molecular mechanisms could induce equivalent phenotypes and that initially divergent cellular responses could converge over time. These findings suggest a conceptual parallel between the actin cytoskeleton and gene regulatory networks; where the theoretical plasticity of interactions is nearly infinite, yet phenotypes observed in vivo are constrained into a limited subset of practicable configurations.

opencc-zeroSep 2020View details →

Transcriptome assembly for: Genetic compensation rather than genetic assimilation drives the evolution of plasticity in response to mild warming across latitudes in a damselfly

Global warming is causing plastic and evolutionary changes in the phenotypes of ectotherms. Yet, we have limited knowledge on how the interplay between plasticity and evolution shapes thermal responses and underlying gene expression patterns. We assessed thermal reaction norm patterns across the transcriptome and identified associated molecular pathways in northern and southern populations of the damselfly Ischnura elegans. Larvae were reared in a common garden experiment at the mean summer water temperatures experienced at the northern (20 °C) and southern (24 °C) latitudes. This allowed a space-for-time substitution where the current gene expression levels at 24 °C in southern larvae are a proxy for the expected responses of northern larvae under gradual thermal evolution to the predicted 4 °C warming. Most differentially expressed genes showed fixed differences across temperatures between latitudes, suggesting that thermal genetic adaptation will mainly evolve through changes in constitutive gene expression. Northern populations also frequently showed plastic responses in gene expression to mild warming, while southern populations were much less responsive to temperature. Thermal responsive genes in northern populations showed to a large extent a pattern of genetic compensation, i.e. gene expression that was induced at 24 °C in northern populations remained at a lower constant level in southern populations, and were associated with metabolic and translation pathways. There was instead little evidence for genetic assimilation of an initial plastic response to mild warming. Our data therefore suggest that genetic compensation rather than genetic assimilation may drive the evolution of plasticity in response to mild warming in this damselfly species.

opencc-zeroOct 2020View details →

Do heterogeneous seascapes of carbonate conditions across biogeographic breaks influence divergent phenotypic plasticity in natural populations?

Aim: Understanding how environmental variability influences stress tolerance, local adaptation, and phenotypic variation among populations is a key challenge for evolutionary ecology and climate change biology. Coastal biogeographic breaks are natural laboratories to explore this fundamental research question due to the contrasting environmental conditions experienced by natural populations across these regions. Location: In the South East Pacific (SEP) coast a major break (30º-32ºS) is characterized by extreme natural variability in seawater carbonate chemistry parameters related to temporal and spatial dynamics in upwelling events. Mollusk species that reach their range limit at this zone are exposed to naturally acidified waters that can be corrosive and impact their calcification, physiology, and fitness, making them particularly prone to the effects of ocean acidification (OA). We investigated to what extent the interplay between biogeographic breaks and local variability of seawater carbonate conditions influences the tolerances and sensitivity of populations of the limpet Scurria araucana to OA. Methods: During two years, we conducted field surveys of limpet populations at sites across the SEP break (27ºS, 30ºS and 32ºS). We collected individuals from each population to test for geographic differences in morphometric (e.g., total buoyancy weight, shell length) and physiological (e.g., oxygen consumption rate, cardiac activity, and thermal performance curves; TPC) responses to local conditions and to simulated OA scenarios. Results: Analysis of the cardiac activity indicates that limpets from the central part of the break (30ºS) exhibit higher thermal performance compared to limpets from populations at both sides of the break. Thus, heterogeneous seascape of carbonate conditions and sea surface temperature across a biogeographic break in the SEP coast influence phenotypic differences among populations of this ecosystem engineer. Main Conclusions: Natural environmental variation might be the underpinning driver of the high tolerance to OA evidenced by populations of the limpet Scurria araucana along the SEP.

Data from: Ecotypes or phenotypic plasticity - the aquatic and terrestrial forms of Helosciadium repens (Apiaceae)

• Morphological and ecological differences of two forms of Helosciadium repens are known and described in the literature: aquatic and terrestrial. However, their taxonomic status is currently unknown. The question whether they are genotypically adapted to specific environmental conditions or are those differences a result of phenotypic plasticity is addressed in this study. • SSR and ISSR data were used to uncover genotypic differences. Data from drought stress experiments (system water content and relative water content of leaves) were used to evaluate the response to water as an environmental factor. The stomatal index of both forms grown under different water treatments was analysed. • The principal component analysis of the SSR and ISSR data revealed no clustering that would correspond with ecotypes. The diversity parameters of the SSR data showed no significant differences. Contrary to the expected pattern, the aquatic populations showed a tendency towards heterozygosity while the terrestrial ones showed a bias towards homozygosity. Both forms responded similarly to the changes in water availability, with newly produced leaves after drought stress that were better adapted to repeated drought stress. Stomatal indices were higher in plants from aquatic habitats, but these difference disappeared when the plants were grown in soil. • The observed responses indicate that the differences between forms are due to phenotypic plasticity.

opencc-zeroDec 2009View details →

Data from: Phenotypic plasticity in sexual communication signal of a noctuid moth

Variability within sex pheromone signalling systems is generally believed to be low because of strong stabilizing selection; yet the noctuid moth Heliothis subflexa (Hs) shows significant intraspecific variation. One possible explanation is that females may alter their sex pheromone blend depending on prevailing olfactory cues in the habitat, which we termed the "experience hypothesis". This could be adaptive if Hs females experiencing the pheromone of another species, Heliothis virescens (Hv), responded to reduce the frequency of heterospecific matings. We exposed Hs females to no pheromone, Hs pheromone, or Hv pheromone in the first 3 days of their adult lives. Hs females in the latter treatment produced signficantly more of the acetate Z11-16:OAc, which inhibits the attraction of Hv males. To our knowledge, this is the first study showing adaptive phenotypic plasticity in a moth sex pheromone, and suggests that behavioral differentiation may precede genetic divergence in the sexual signals of moths.

zenodo28/100

Data and R code for: Tariel J., Plénet S., and Luquet É. (2020). How do developmental and parental exposures to predation affect personality and immediate behavioural plasticity in the snail Physa acuta?

Data and R code of the article: Tariel J., Plénet S., and Luquet É. (2020) How do developmental and parental exposures to predation affect personality and immediate behavioural plasticity in the snail Physa acuta? doi:<a href="http://doi.org/10.1098/rspb.2020.1761">10.1098/rspb.2020.1761</a> The dataset is provided (data -Tariel, Plénet and Luquet (2020).csv). This dataset is analyzed in the R script (Juliette Tariel - R analysis.Rmd). A knitted version of the R script is also provided in pdf format (Juliette Tariel - R analysis.pdf). Finally, a zip file is provided and contains several outputs, such as MCMCglmm objects or confint objects (R outputs used in the analysis.zip) Signification of variables names: <ul> <li>ID: snail's identification number</li> <li>ID Family: identification number of the family of the F2 snail</li> <li>ID F1 mother: identification number of the mother of the F2 snail</li> <li>ID F1 father: identification number of the father of the F2 snail</li> <li>ID F0 grand-mother: identification number of the grand-mother of the F2 snail</li> <li>ID F0 grand-father: identification number of the grand-fathrt of the F2 snail</li> <li>Mass: total wet mass (body and shell) in grams</li> <li>Parental: parental environment (control C or predator-cue P)</li> <li>Developmental: developmental environment (C or P)</li> <li>Immediate: immediate environment (C or P)</li> <li>Trial_number</li> <li>Time: time to crawl-out of the water in seconds</li> </ul>

opencc-by-4.0Nov 2020View details →

zenodo28/100

Data from: eDNA metabarcoding reveals a core and secondary diets of the greater horseshoe bat with strong spatio-temporal plasticity

ABSTRACT Dietary plasticity is an important issue for conservation biology as it may be essential for species to cope with environmental changes. However, it still remains scarcely addressed in the literature, potentially because diet studies have long been constrained by methodological limits. The advent of molecular approaches now makes it possible to get a precise picture of diet and its plasticity, even for endangered and elusive species. Here we focused on the greater horseshoe bat (Rhinolophus ferrumequinum) in Western France, where this insectivorous species has been classified as ‘Vulnerable’ on the Regional Red List (2016). We applied an eDNA metabarcoding approach on 1986 fecal samples collected in six maternity colonies at three sampling dates. We described its diet and investigated whether the landscape surrounding colonies and the different phases of the maternity cycle influenced the diversity and the composition of this diet. We showed that R. ferrumequinum feed on a highly more diverse spectrum of prey than expected from previous studies, therefore highlighting how eDNA metabarcoding can help improving diet knowledge of a flying elusive endangered species. Our approach also revealed that R. ferrumequinum diet is composed of two distinct features: the core diet consisting in a few preferred taxa shared by all the colonies (25% of the occurrences) and the secondary diet consisting in numerous rare prey that were highly different between colonies and sampling dates (75% of the occurrences). Energetic needs and constraints associated with the greater horseshoe bat life-cycle, as well as insect phenology and landscape features, strongly influenced the diversity and composition of both the whole and core diets. Further research should now explore the relationships between R. ferrumequinum dietary plasticity and fitness, to better assess the impact of core prey decline on R. ferrumequinum populations viability.   FILE DESCRIPTION Information concerning the samples and the positive and negative controls multiplexed in the MiSeq Runs 5 to 9 This XLSX file contains the sample IDs, the sample types, the PCR IDs, the PCR replicate numbers, the locality names, the predator species and the fastq file names for each PCR products multiplexed in the five different Illumina MiSeq runs. File name: Sample_informations.xlsx   MiSeq raw sequences of the COI minibarcode from the faecal pellets of bats (Run5) This ZIP file contains the Run5 FASTQ files of the paired-end reads (R1: reads 1; R2: reads 2) produced for each faecal pellet in triplicate using the MiSeq platform. The 1271 multiplexed PCR products were indexed using both forward and reverse indices. The list of the 475 multiplexed samples and the 8 positive and 94 negative controls are provided in the following XLSX file titled: Sample_Information.xlsx. Note: the 186 PCR3 replicates from the localities BEA and SGE are available in the ZIP file MiSeq_Reads_COI_Bat_faecal_pellets_Run9.zip File name: MiSeq_Reads_COI_Bat_faecal_pellets_Run5.zip   MiSeq raw sequences of the COI minibarcode from the faecal pellets of bats (Run6) This ZIP file contains the Run6 FASTQ files of the paired-end reads (R1: reads 1; R2: reads 2) produced for each faecal pellet in triplicate using the MiSeq platform. The 1440 multiplexed PCR products were indexed using both forward and reverse indices. The list of the 466 multiplexed samples and the 8 positive and 130 negative controls are provided in the following XLSX file titled: Sample_Information.xlsx. File name: MiSeq_Reads_COI_Bat_faecal_pellets_Run6.zip   MiSeq raw sequences of the COI minibarcode from the faecal pellets of bats (Run7) This ZIP file contains the Run7 FASTQ files of the paired-end reads (R1: reads 1; R2: reads 2) produced for each faecal pellet in triplicate using the MiSeq platform. The 1464 multiplexed PCR products were indexed using both forward and reverse indices. The list of the 475 multiplexed samples and the 8 positive and 103 negative controls are provided in the following XLSX file titled: Sample_Information.xlsx. File name: MiSeq_Reads_COI_Bat_faecal_pellets_Run7.zip   MiSeq raw sequences of the COI minibarcode from the faecal pellets of bats (Run8) This ZIP file contains the Run8 FASTQ files of the paired-end reads (R1: reads 1; R2: reads 2) produced for each faecal pellet in triplicate using the MiSeq platform. The 1464 multiplexed PCR products were indexed using both forward and reverse indices. The list of the 475 multiplexed samples and the 8 positive and 103 negative controls are provided in the following XLSX file titled: Sample_Information.xlsx. File name: MiSeq_Reads_COI_Bat_faecal_pellets_Run8.zip   MiSeq raw sequences of the COI minibarcode from the faecal pellets of bats (Run9) This ZIP file contains the Run9 FASTQ files of the paired-end reads (R1: reads 1; R2: reads 2) produced for each faecal pellet in triplicate using the MiSeq platform. The 499 multiplexed PCR products were indexed using both forward and reverse indices. The list of the 281 multiplexed samples (including 29 samples from another project) and the 11 positive and 172 negative controls are provided in the following XLSX file titled: Sample_Information.xlsx. Note: the 372 PCR1 & PCR2 replicates from the localities BEA and SGE are available in the ZIP file MiSeq_Reads_COI_Bat_faecal_pellets_Run5.zip File name: MiSeq_Reads_COI_Bat_faecal_pellets_Run9.zip   Raw abundance tables of the COI minibarcode from the faecal pellets of bats before data filtering (Run5 to 9) This ZIP file contains five TXT files showing the number of reads for each of the 17,998 distinct variants (OTUs) and each of the 6138 PCR products of the samples (n=2015) and controls sequenced in the MiSeq Runs 5 to 9 before the data filtering. File name: Raw_COI_Bat_Faecal_Pellets_abundance_Runs5to9_before_filtering.zip   Abundance table of the COI minibarcode from the faecal pellets of bats after data filtering (Run5 to 9) This XLSX file contains the number of reads for each of the 7206 distinct variants (OTUs) and each of sample (n=2014) after the data filtering using (1) the thresholds based on the negative and positive controls (Tcc & Tfa) and (2) the validation using the three technical replicates. File name: COI_Bat_Faecal_Pellets_abundance_Runs5to9_after_filtering.xlsx   Final abundance table of the COI minibarcode for the prey of Rhinolophus ferrumequinum only (Run5 to 9) This XLSX file contains the number of reads for each Rhinolophus ferrumequinum samples (n=1034) and each of the 679 validated prey taxa (OTUs) after taxonomic affiliations check and redundancy removals. File name: Final_COI_Rhino_Prey_abundance_Run5to9.xlsx   Landscape data table used to build the PCA File name: Landscape_variables.xlsx

opencc-by-4.0May 2020View details →

Kin-mediated plasticity in alternative reproductive tactics

Conditional strategies occur when the fitness payoff an individual receives from expressing a given phenotype (from a range of two or more possible phenotypes) is contingent upon that individual's environmental circumstances. This conditional strategy model underlies many cases of alternative reproductive tactics, in which individuals of one sex employ different means to obtain reproductive opportunities. How genetic relatedness and indirect fitness effects could affect the expression of alternative reproductive tactics remains unexplored. Here, we address this gap using the Acarid mite Rhizoglyphus echinopus, in which large males develop into aggressive 'fighters' and small males develop into non-aggressive 'scramblers.' Because fighters kill their rivals whereas scramblers do not, fighters should incur a greater indirect fitness cost when competing with their relatives, and thus the expression of the fighter phenotype could be reduced in the presences of relatives. To test this, we raised mites in full-sibling or mixed-sibship groups and found that fighters were more common in full-sibling groups, not less common as we predicted. This apparently counter-intuitive result could be explained if relatedness and cue variability are interpreted as a signal of population density, since fighters are more common at low densities in this species. Alternatively, our results may indicate that males compete more intensely with relatives than non-relatives in this species. Our study provides the first evidence of kin-mediated plasticity in the expression of alternative reproductive tactics.

A three year trans-generational plasticity in life history traits

1. Environmental conditions of maternal plants influence adaptive strategies of their progeny via the seed phenotype. Although traditionally, studies have explained patterns of reproduction traits in response to stresses, such as the changes in seed mass and seed germinability under different maternal conditions. However, it is still unclear how maternal effects affect progeny dispersal and germination strategy or how many generations plasticity persists. 2. Plants from diaspore types A and C of the diaspore-heteromorphic annual halophyte Atriplex centralasiatica were grown in low (favorable) vs. high (stressful) salinities over three generations in a fully factorial design. We measured life history traits and reproductive characteristics of progeny plants for a three-year transgenerational plasticity (TGP) experiment covering F0, F1, and F 3. TGP of plants grown in favorable vs. stressful salinities decreased from F2 → F1 → F0. Compared to the favorable condition, the stressful condition decreased the length of the vegetative period, extended length of reproductive time and increased reproductive allocation and size of progeny diaspores. Salinity tolerance and phenotypic plasticity were higher in plants from diaspore A than in those from diaspore C. In the stressful condition, plants produced less plant biomass, larger diaspores, a higher proportion of type C diaspores with dormancy and higher dispersal potential, but lower proportion of type A diaspores with nondormancy and lower dispersal potential. In addition, production of the proportion of type C diaspores increased with increase in number of previous generations that experienced stress. 4. Synthesis: The trade-off of reproductive allocation between diaspores A versus C enables plants to develop divergent strategies via both high diaspore C allocation to disperse progeny spatiotemporally across wide areas in stress conditions and high diaspore A allocation to limit progeny near maternal plants in favorable habitats. These findings provide evidence for the "escape strategy" by which the progeny of A. centralasiatica diffused spatially (dispersal) and temporally (dormancy) by TGP, thus allowing them to survive environmental heterogeneity in their cold desert habitats.

Data from: Phenotypic plasticity, but not adaptive tracking, underlies seasonal variation in post-cold hardening freeze tolerance of Drosophila melanogaster

In temperate regions, an organism's ability to rapidly adapt to seasonally varying environments is essential for its survival. In response to seasonal changes in selection pressure caused by variation in temperature, humidity, and food availability, some organisms exhibit plastic changes in phenotype. In other cases, seasonal variation in selection pressure can rapidly increase the frequency of genotypes that offer survival or reproductive advantages under the current conditions. Little is known about the relative influences of plastic and genetic changes in short lived organisms experiencing seasonal environmental fluctuations. Cold hardening is a seasonally relevant plastic response in which exposure to cool, but nonlethal, temperatures significantly increases the organism's ability to later survive at freezing temperatures. In the present study, we demonstrate seasonal variation in cold hardening in Drosophila melanogaster and test the extent to which plasticity and adaptive tracking underlie that seasonal variation. We measured the post-cold hardening freeze tolerance of flies from outdoor mesocosms over the summer, fall, and winter. We bred outdoor mesocosm-caught flies for two generations in the lab and matched each outdoor cohort to an indoor control cohort of similar genetic background. We cold hardened all flies under controlled laboratory conditions and then measured their post-cold hardening freeze tolerance. Comparing indoor and field-caught flies and their laboratory-reared G1 and G2 progeny allowed us to determine the roles of seasonal environmental plasticity, parental effects, and genetic changes on cold hardening. We also tested the relationship between cold hardening and other factors, including age, developmental density, food substrate, presence of antimicrobials, and supplementation with live yeast. We found strong plastic responses to a variety of field- and lab-based environmental effects, but no evidence of seasonally varying parental or genetic effects on cold hardening. We therefore conclude that seasonal variation in post-cold hardening freeze tolerance results from environmental influences and not genetic changes.

Ancestral genetic variation in phenotypic plasticity underlies rapid evolutionary changes in resurrected populations of waterfleas

The role that phenotypic plasticity plays in adaptive evolution has been debated for decades. This is because the strength of natural selection is dependent upon the direction and magnitude of phenotypic responses to environmental signals. Therefore, the connection between plasticity and adaptation will depend on the patterns of plasticity harbored by ancestral populations prior to a change in the environment. Yet, few studies have directly assessed ancestral variation in plasticity and tracked phenotypic changes over time. Here we resurrected historic propagules of Daphnia spanning multiple species and lakes in Wisconsin following the invasion and proliferation of a novel predator (spiny waterflea, Bythotrephes longimanus). This approach revealed extensive genetic variation in predator-induced plasticity in ancestral populations of Daphnia. It is unlikely that the standing patterns of plasticity shielded Daphnia from selection to permit long-term coexistence with a novel predator. Instead, this variation in plasticity provided the raw materials for Bythotrephes-mediated selection to drive rapid shifts in Daphnia behavior and life history. Surprisingly, there was little evidence for the evolution of trait plasticity as genetic variation in plasticity was maintained in the face of a novel predator. Such results provide new insights into the link between plasticity and adaptation and highlight the importance of quantifying genetic variation in plasticity when evaluating the drivers of evolutionary change in the wild.

Oxygen-mediated plasticity confers hypoxia tolerance in a corallivorous polychaete

There is mounting evidence that the deoxygenation of coastal marine ecosystems has been underestimated, particularly in the tropics. These physical conditions appear to have far-reaching consequences for marine communities, and have been associated with mass mortalities. Yet little is known about hypoxia in tropical habitats or about the effects it has on reef-associated benthic organisms. We explored patterns of dissolved oxygen (DO) throughout Almirante Bay, Panama and found a hypoxic gradient, with areas closest to the mainland having the largest diel variation in DO, as well as more frequent persistent hypoxia. We then designed a laboratory experiment replicating the most extreme in situ DO regime found on shallow patch reefs (3 m) to assess the response of the corallivorous fireworm, Hermodice carnaculata to hypoxia. Worms were exposed to hypoxic conditions (8 h ~ 1 mg l-1 or 3.2 kPa) 16 times over an 8-week period, and at 4 and 8 weeks their oxygen consumption (respiration rates) were measured upon reoxygenation, along with regrowth of severed gills. Exposure to low DO resulted in worms regenerating significantly larger gills compared to worms under normoxia. This response to low DO was coupled with an ability to maintain elevated oxygen consumption/respiration rates after low DO exposure. In contrast, worms from the normoxic treatment had significantly depressed respiration rates after being exposed to low DO (week 8). This indicates that oxygen-mediated plasticity in both gill morphology and physiology may confer tolerance to increasingly frequent and severe hypoxia in one important coral predator associated with reef decline.

Data from: A condition-dependent male sexual signal predicts adaptive predator-induced plasticity in offspring

The possibility that sexual selection promotes adaptive evolution in variable environments remains controversial. In particular, where the scale of environmental variation results in parents and their offspring experiencing different environmental conditions, such variation is expected to break down associations between adult sexual traits and adaptive offspring traits. However, when adaptive offspring plasticity in nonsexual traits acts as an indirect benefit of mate choice, then mate choice for males that produce more plastic offspring could promote adaptation to variable environments. This hypothesis assumes that male sexual signals predict offspring plasticity, which has rarely been tested. To test this assumption, we used spadefoot toads (Spea multiplicata) to investigate whether variation in male sexual signals predicts the expression of tadpole tail-fin plasticity in response to predation cues. Such plasticity has been shown to be adaptive in numerous amphibian taxa. We found that condition-dependent male call characteristics predicted offspring plasticity. Generally, both phenotypic plasticity and female mate choice are ubiquitous in nature; therefore, adaptive associations between male sexual signals and offspring plasticity such as the one reported here might be common.

Data from: Plasticity matches phenotype to local conditions despite genetic homogeneity across 13 snake populations

In a widespread species, a matching of phenotypic traits to local environmental optima is generally attributed to site-specific adaptation. However, the same matching can occur via adaptive plasticity, without requiring genetic differences among populations. Adult sea kraits (Laticauda saintgironsi) are highly philopatric to small islands, but the entire population within the Neo-Caledonian lagoon is genetically homogenous because females migrate to the mainland to lay their eggs at communal sites; recruits disperse before settling, mixing up alleles. Consequently, any adaptive matching between local environments (e.g., prey sizes) and snake phenotypes (e.g., body sizes and relative jaw sizes) must be achieved via phenotypic plasticity rather than spatial heterogeneity in gene frequencies. We sampled 13 snake colonies spread along a ~200km northwest-southeast gradient (N>4,500 individuals) to measure two morphological features that affect maximum ingestible prey size in gape-limited predators: body size and relative jaw size. As proxies of habitat quality, we used protection status, fishing pressure and lagoon characteristics (lagoon width and distance of islands to the barrier reef). In both sexes, spatial variation in body sizes and relative jaw sizes was linked to habitat quality; albeit in different ways, consistent with sex-based divergences in foraging ecology. Strong spatial divergence in morphology among snake colonies, despite genetic homogeneity, supports the idea that phenotypic plasticity can facilitate speciation by creating multiple phenotypically distinct sub-populations shaped by their environment.

opencc-zeroDec 2018View details →

Data from: Species' range dynamics affect the evolution of spatial variation in plasticity under environmental change

While clines in environmental tolerance and phenotypic plasticity along a single species' range have been reported repeatedly and are of special interest in the context of adaptation to environmental changes, we know little about their evolution. Recent empirical findings in ectotherms suggest that processes underlying dynamic species' ranges can give rise to spatial differences in environmental tolerance and phenotypic plasticity within species. We used individual-based simulations to investigate how plasticity and tolerance evolve in the course of three scenarios of species' range shifts and range expansions on environmental gradients. We found that regions of a species' range which experienced a longer history or larger extent of environmental change generally exhibited increased plasticity or tolerance. Such regions may be at the trailing edge when a species is tracking its ecological niche in space (e.g., in a climate change scenario) or at the front edge when a species expands into a new habitat (e.g., in an expansion/invasion scenario). Elevated tolerance and plasticity in the distribution center was detected when asymmetric environmental change (e.g., polar amplification) led to a range expansion. However, tolerance and plasticity clines were transient and slowly flattened out after range dynamics because of genetic assimilation.