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Predation risk shapes the use of conflicting personal risk and social safety information in guppies

When faced with uncertainty, animals can benefit from using multiple sources of information in order to make an optimal decision. However, information sources (e.g., social and personal cues) may conflict, while also varying in acquisition cost and reliability. Here, we assessed behavioral decisions of Trinidadian guppies (Poecilia reticulata), in situ, when presented with conflicting social and personal information about predation risk. We positioned foraging arenas within high- and low-predation streams, where guppies were exposed to a personal cue in the form of conspecific alarm cues (a known indicator of risk), a novel cue, or a control. At the same time, a conspecific shoal (a social safety cue) was either present or absent. When social safety was absent, guppies in both populations showed typical avoidance responses towards alarm cues, and high-predation guppies showed their typical avoidance of novel cues (i.e., neophobia). However, the presence of social safety cues was persuasive, overriding the neophobia of high-predation guppies and emboldening low-predation guppies to ignore alarm cues. Our experiment is one of the first to empirically assess the use of safety and risk cues in prey, and suggests a threshold level of ambient risk which dictates the use of conflicting social and personal information.

Multicellularity and sex helped shape the Tree of Life

Across the Tree of Life, there are dramatic differences in species numbers among groups. However, the factors that explain the differences among the deepest branches have remained unknown. We tested whether multicellularity and sexual reproduction might explain these patterns, since the most species-rich groups share these traits. We found that groups with multicellularity and sexual reproduction have accelerated rates of species proliferation (diversification), and that multicellularity has a stronger effect than sexual reproduction. Patterns of species richness among clades are then strongly related to these differences in diversification rates. Taken together, these results help explain patterns of biodiversity among groups of organisms at the very broadest scales. They may also help explain the mysterious preponderance of sexual reproduction among species (the "paradox of sex") by showing that organisms with sexual reproduction proliferate more rapidly.

Climate warming dominates over plant genotype in shaping the seasonal trajectory of foliar fungal communities on oak

Leaves interact with a wealth of microorganisms. Among these, fungi are highly diverse, and are known to contribute to plant health, leaf senescence and early decomposition. However, patterns and drivers of the seasonal dynamics of foliar fungal communities are poorly understood. We used a multi-factorial experiment to investigate the influence of warming and tree genotype on the foliar fungal community on the pedunculate oak Quercus robur across one growing season. Fungal species richness increased, evenness tended to decrease, and community composition strongly shifted during the growing season. Yeasts increased in relative abundance as the season progressed, while putative fungal pathogens decreased. Warming decreased species richness, reduced evenness and changed community composition, especially in the end of the growing season. Warming also negatively affected putative fungal pathogens. We only detected a minor imprint of tree genotype and warming-by-genotype interactions on species richness and community composition. Overall, our findings demonstrate that warming plays a larger role than plant genotype in shaping the seasonal dynamics of the foliar fungal community on oak. These warming-induced shifts in the foliar fungal community may have a pronounced impact on plant health, plant-fungal interactions and ecosystem functions.

Data from: Leaf shape in Populus tremula is a complex, omnigenic trait.

Leaf shape is a defining feature of how we recognise and classify plant species. Although there is extensive variation in leaf shape within many species, few studies have disentangled the underlying genetic architecture. We characterised the genetic architecture of leaf shape variation in Eurasian aspen (Populus tremula L.) by performing a genome wide association studies (GWAS) for physiognomy traits. To ascertain the roles of identified GWAS candidate genes within the leaf development transcriptional program, we performed gene co-expression network analyses from a developmental series, which is publicly available within the PlantGenIE resource. We additionally used gene expression measurements across the population to analyse GWAS candidate genes in the context of a population-wide co-expression network and to identify genes that were differentially expressed between groups of individuals with contrasting leaf shapes. These data were integrated with expression GWAS (eQTL) results to define a set of candidate genes associated with leaf shape variation. Our results identified no clear adaptive link to leaf shape variation and indicate that leaf shape traits are genetically complex, likely determined by numerous small-effect variations in gene expression. Genes associated with shape variation were peripheral within the population-wide co-expression network, were not highly connected within the leaf development co-expression network and exhibited signatures of relaxed selection. As such, our results are consistent with the omnigenic model.

Oceanographic features and limited dispersal shape the population genetic structure of the vase sponge Ircinia campana in the Greater Caribbean

Understanding population genetic structure can help us to infer dispersal patterns, predict population resilience and design effective management strategies. For sessile species with limited dispersal, this is especially pertinent because genetic diversity and connectivity are key aspects of their resilience to environmental stressors. Here, we describe the population structure of Ircinia campana, a common Caribbean sponge subject to mass mortalities and disease. Microsatellites were used to genotype 440 individuals from 19 sites throughout the Greater Caribbean. We found strong genetic structure across the region, and significant isolation by distance across the Lesser Antilles, highlighting the influence of limited larval dispersal. We also observed spatial genetic structure patterns congruent with oceanography. This includes evidence of connectivity between sponges in the Florida Keys and the southeast coast of the United States (>700 km away) where the oceanographic environment is dominated by the strong Florida Current. Conversely, the population in southern Belize was strongly differentiated from all other sites, consistent with the presence of dispersal-limiting oceanographic features, including the Gulf of Honduras gyre. At smaller spatial scales (<100 km), sites showed heterogeneous patterns of low-level but significant genetic differentiation (chaotic genetic patchiness), indicative of temporal variability in recruitment or local selective pressures. Genetic diversity was similar across sites, but there was evidence of a genetic bottleneck at one site in Florida where past mass mortalities have occurred. These findings underscore the relationship between regional oceanography and weak larval dispersal in explaining population genetic patterns, and could inform conservation management of the species.

opencc-zeroDec 2020View details →

Predation shapes behavioral lateralization: insights from an adaptive radiation of livebearing fish

Hemispheric brain lateralization can drive the expression of behavioral asymmetry, or laterality, which varies notably both within and among species. To explain these left–right behavioral asymmetries in animals, predator-mediated selection is often invoked. Recent studies have revealed that a relatively high degree of lateralization correlates positively with traits known to confer survival benefits against predators, including escape performance, multitasking abilities, and group coordination. Yet, we still know comparatively little about 1) how consistently predators shape behavioral lateralization, 2) the importance of sex-specific variation, and 3) the degree to which behavioral lateralization is heritable. Here, we take advantage of the model system of the radiation of Bahamas mosquitofish (Gambusia hubbsi) and measure behavioral lateralization in hundreds of wild fish originating from multiple blue holes that differ in natural predation pressure. Moreover, we estimated the heritability of this trait using laboratory-born fish from one focal population. We found that the degree of lateralization but not the particular direction of lateralization (left or right) differed significantly across high and low predation risk environments. Fish originating from high-predation environments were more strongly lateralized, especially females. We further confirmed a genetic basis to behavioral lateralization in this species, with significant additive genetic variation in the population examined. Our results reveal that predation risk represents one key ecological factor that has likely shaped the origin and maintenance of this widespread behavioral phenomenon, even potentially explaining some of the sex-specific patterns of laterality recently described in some animals.

opencc-zeroAug 2021View details →

Data for: Spontaneous choices for insect-pollinated flower shapes by wild non-eusocial halictid bees

The majority of angiosperms require animal pollination for reproduction and insects are the dominant group of animal pollinators. Bees are considered one of the most important and abundant insect pollinators. Research into bee behaviour and foraging decisions has typically centred on managed eusocial bee species, Apis mellifera and Bombus terrestris. Non-eusocial bees are understudied with respect to foraging strategies and decision-making, such as flower preferences. Understanding whether there are fundamental foraging strategies and preferences which are features of insect groups can provide key insights into the evolution of flower-pollinator co-evolution. In the current study, Lasioglossum (Chilalictus) lanarium and L. (Parasphecodes) sp., two native Australian generalist halictid bees, were tested for flower shape preferences between native insect-pollinated and bird-pollinated flowers. Each bee was presented with achromatic images of either insect-pollinated or bird-pollinated flowers in a circular arena. Both native bee species demonstrated a significant preference for images of insect-pollinated flowers. These preferences are similar to those found in A. mellifera, suggesting that flower shape preference may be a deep-rooted evolutionary occurrence within bees. With growing interest in the sensory capabilities of non-eusocial bees as alternative pollinators, the current study also provides a valuable framework for further behavioural testing of such species.

opencc-zeroAug 2021View details →

Growth-defense tradeoffs shape the genetic composition of aspen forests

All organisms experience fundamental conflicts between divergent metabolic processes. In plants, a pivotal conflict occurs between allocation to growth, which accelerates resource acquisition, and to defense, which protects existing tissue against herbivory. Tradeoffs between growth and defense traits are not universally observed, and a fundamental prediction of plant evolutionary ecology is that context-dependence of these tradeoffs contributes to the maintenance of intraspecific variation in defense. This prediction has rarely been tested, however, and the evolutionary consequences of growth-defense tradeoffs in different environments are poorly understood. Here we show that intraspecific trait tradeoffs interact with competitive environment to drive natural selection of tree genotypes corresponding to their growth-defense phenotypes. Our results show for the first time that a functional trait tradeoff, when coupled with environmental variation, causes real-time divergence in the genetic architecture of forest stands. Specifically, competitive selection for faster growth resulted in dominance by fast-growing tree genotypes that were poorly defended against natural enemies. This outcome is a signature example of eco-evolutionary dynamics: competitive interactions affected microevolutionary trajectories on a timescale relevant to subsequent ecological interactions. Eco-evolutionary drivers of tree growth and defense are thus critical to stand-level trait variation, which structures communities and ecosystems over expansive spatiotemporal scales.

Figure 5 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 5. Scatterplot of the relationship of PC1 on body weight separated by group (a), on body weight separated by sex (b), OvWBW (c) and NgWBW (d) for females separated by group.

Figure 3 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 3. Schematic representation of the series of growth increments (GINC) read over the dorsal surface of the gladius, the filtering process and the back-calculation of the gladius growth.

Figure 1 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 1. Spatial representation of the study area. (a–c) Positions of the samples of Illex argentinus collected from trawlers south-southeast of Brazil between 22° and 33°S and 45 and 722 m depth from 2001 to 2013. (b) Samples used in geometric morphometric analysis. (c) Samples used in traditional morphometric analysis. (d) Samples collected during a research cruise during August of 2004 in the same area to identify size-selective processes. Lines in maps represent 100, 300 and 700 m depth.

Figure 4 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 4. Length distributions of the (a) Local Group (LG) and the (b) Migratory Group (MG) captured south-southeast of Brazil between 2009 and 2013. Scatterplots of the first (PC1) and second (PC2) components of the principal component analysis using body landmarks separated by group (c) and by sex (d). Scatterplot of relationship of PC1 on centroid size separated by group (e) and by sex (f).

Figure 2 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 2. Landmark configuration on the body of Illex argentinus. Dashed line represents the longitudinal axis of the body.

Figure 8 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 8. Length distributions of Illex argentinus captured in south-southeastern Brazil between 22° and 33°S and 45 and 722 m depth from 2001 to 2013.

Figure 7 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 7. (a) Mean gladius length (GL) in research cruise, and (b) mean individuals recent growth trajectories of squid captured in research cruise reconstructed from gladius.

Figure 10 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 10. Size differentiation of squid groups during the period of growth reconstructed expressed by the variation of the coefficient of asymmetry (g1) of the length frequency distributions by growth interval (days).

Figure 9 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 9. Gladius length frequency distributions of Illex argentinus reconstructed for the last 15 days before the capture from the measured increments on the gladius for the trawls 2–4 (T2-4) and trawls 9–14 (T9-14) of the research cruise.

Figure 6 in Analysis of shape variability and life history strategies of Illex argentinus in the northern extreme of species distribution as a tool to differentiate spawning groups

Figure 6. Barplots represents the length distributions of males and females of Illex argentinus captured during the fourth trimester of 2006 south-southeast of Brazil and a sample from the Uruguayan/Argentine common fishing zone collected in 2005, here defined as pre-migratory group (J). The analysis aimed to verify a possible correspondence between J and the expected MG, represented by two samples collected in the south (S) and central (C) portions of the studied area and if J is morphometrically different from the LG, captured in the north (N) portion of study area (Figure 1(c)). Plots represent the principal component analysis of the samples N, C, S and J. FRAL, length of the fourth right arm; BW, body weight; MW, mantle weight; MP, mantle perimeter.

opencc-zeroAug 2021View details →

Data from: Climate and vegetation structure shape ant communities along elevational gradients on the Colorado Plateau

Aim: Terrestrial animal communities are largely shaped by vegetation and climate. With climate also shaping vegetation, can we attribute animal patterns solely to climate? To understand this, we compare the relative and interactive effects of climate and vegetation on an animal community. Our study observes ant community changes along climatic gradients (i.e. elevational gradients) within different habitat types (i.e. open and forest). We compare the explanatory powers and effect sizes of climate and vegetation variables on ant communities and describe what drives elevational distributions of ant species. Location: Colorado Plateau, southwestern United States Taxon: Formicidae Methods: We sampled ants and vegetation along two elevational gradients spanning 1132m with average annual temperature and precipitation differences of 5.7C° and 645 mm, respectively. Regression analysis and structural equation modeling was then used to test the relative effects of climate and vegetation variables on ant communities. Results: Climate variables had the strongest correlations and the largest effect sizes on ant communities, while vegetation composition, richness, and primary productivity were relatively small. Precipitation was the strongest predictor for most ant community metrics. Ant richness and abundance had a negative relationship with precipitation in forested habitats, and positive in open habitats. Main conclusions: Our results show strong direct climate effects on ants with little or no effects of vegetation composition or primary productivity, but contrasting patterns between vegetation type (i.e. forested vs open) with precipitation. This indicates vegetation structure can modulate climate responses of ant communities. Our study demonstrates climate-animal relationships may vary among vegetation types which can impact both findings from elevational studies and how communities will react to changes in climate.