Not Extremely Plastic: Testing the Limits of Morphological Plasticity in Fungal Mycelia in Response to Soil Grazers

We conducted an experiment to assess the change in foraging efficiency resulting from diet-induced morphological and behavioural plasticity in a species of freshwater, threespine stickleback (Gasterosteus sp.). Different degrees of morphological and behavioural change were induced using two prey items commonly found in the diet of this species, allowing us to estimate the relative importance of each type of plasticity. The purpose of the experiment was twofold. First, earlier work had suggested that diet variability might be an important factor in the evolution of trophic morphological plasticity in sticklebacks. The present results extend this work by revealing the adaptive significance of morphological plasticity. The current experiment also qualitatively assessed the compatibility of the time scale of morphological change with that of the natural resource variability experienced by this species. The results indicate that diet-induced plasticity improves foraging efficiency continuously for up to 72 days of prey exposure. This is probably due in part to plasticity of the external trophic morphology but our results also suggest a complex interplay between morphology and behaviour. The time scale appears to be matched to that of natural diet variability although it is possible that some traits exhibit non-labile plasticity. Our discussion highlights the important distinction between conditions favouring the evolution of labile versus non-labile plasticity. The second objective of the experiment was to determine the relative importance of morphological and behavioural plasticity. Few studies have attempted to quantify the adaptive significance of morphological plasticity and no study to our knowledge has separated the effects of morphological and behavioural plasticity. Our experiment reveals that both behavioural and morphological plasticity are important and it also suggests a dichotomy between the two: behavioural plasticity predominately affects searching efficiency whereas morphological plasticity predominately affects handling efficiency.

Potential constraints on the evolution of phenotypic plasticity were tested using data from a previous study on predator‐induced morphology and life history in the freshwater snail Physa heterostropha. The benefit of plasticity can be reduced if facultative development is associated with energetic costs, developmental instability, or an impaired developmental range. I examined plasticity in two traits for 29 families of P. heterostropha to see if it was associated with growth rate or fecundity, within‐family phenotypic variance, or the potential to produce extreme phenotypes. Support was found for only one of the potential constraints. There was a strong negative selection gradient for growth rate associated with plasticity in shell shape (β = −0.3, P < 0.0001). This result was attributed to a genetic correlation between morphological plasticity and an antipredator behavior that restricts feeding. Thus, reduced growth associated with morphological plasticity may have had unmeasured fitness benefits. The growth reduction, therefore, is equivocal as a cost of plasticity. Using different fitness components (e.g., survival, fecundity, growth) to seek constraints on plasticity will yield different results in selection gradient analyses. Procedural and conceptual issues related to tests for costs and limits of plasticity are discussed, such as whether constraints on plasticity will be evolutionarily ephemeral and difficult to detect in nature.

Understanding is currently limited of the biological processes underlying the responses of modular organisms to climate change and the potential to adapt through morphological plasticity related to their modularity. Here, we investigate the effects of ocean acidification and seawater warming on the growth, life history and morphological plasticity in the modular bryozoan Calpensia nobilis using transplantation experiments in a shallow Mediterranean volcanic CO2 vents system that simulates pH values expected for the year 2100. Colonies exposed at vent sites grew at approximately half the rate of those from the control site. Between days 34 and 48 of the experiment, they reached a possible ‘threshold’, due to the combined effects of exposure time and pH. Temperature did not affect zooid length, but longer zooids with wider primary orifices occurred in low pH conditions close to the vents. Growth models describing colony development under different environmental scenarios suggest that stressed colonies of C. nobilis reallocate metabolic energy to the consolidation and strengthening of existing zooids. This is interpreted as a change in life-history strategy to support persistence under unfavourable environmental conditions. Changes in the skeletal morphology of zooids evident in C. nobilis during short-time (87 days) exposure experiments reveal morphological plasticity that may indicate a potential to adapt to the more acidic Mediterranean predicted for the future.

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 43:31-39 (2010) - DOI: https://doi.org/10.3354/cr00878 Contrasting effects of environmental factors during larval stage on morphological plasticity in post-metamorphic frogs Miguel Tejedo1,*, Federico Marangoni1,2, Cino Pertoldi3, Alex Richter-Boix4, Anssi Laurila4, Germán Orizaola4, Alfredo G. Nicieza5, David Álvarez5, Iván Gomez-Mestre5,6 1Department of Evolutionary Ecology, Estación Biológica de Doñana, CSIC, Avda. Américo Vespucio s/n, 41092 Sevilla, Spain 2Laboratorio de Genética Evolutiva, FCEQyN-UnaM/CONICET, Félix de Azara 1552, 6to Piso 3300 Posadas – Misiones, Argentina 3Department of Ecology and Genetics, Institute of Biological Sciences, University of Aarhus, Denmark 4Department of Population Biology and Conservation Biology, Evolutionary Biology Centre (EBC), Uppsala University, Norbyvägen 18 D, 752 36 Uppsala, Sweden 5Ecology Unit, Department of Biology of Organisms and Systems, University of Oviedo, 33071 Oviedo, and Cantabrian Institute of Biodiversity (ICAB), Spain 6Department of Wetland Ecology, Estación Biológica de Doñana, CSIC, Avda. Américo Vespucio s/n, 41092 Sevilla, Spain *Email: tejedo@ebd.csic.es ABSTRACT: In organisms with complex life cycles, environmentally induced plasticity across sequential stages can have important consequences on morphology and life history traits such as developmental and growth rates. However, previous research in amphibians and other ectothermic vertebrates suggests that some morphological traits are generally insensitive to environmental inductions. We conducted a literature survey to examine the allometric responses in relative hind leg length and head shape of post-metamorphic anuran amphibians to induced environmental (temperature, resource level, predation and desiccation risk) variation operating during the larval phase in 44 studies using 19 species. To estimate and compare plastic responses across studies, we employed both an index of plasticity and effect sizes from a meta-analysis. We found contrasting trait responses to different environmental cues. Higher temperatures increased development more than growth rate and induced smaller heads but not overall shifts in hind leg length. In contrast, an increment in resource availability increased growth more than development, with a parallel increase in hind leg length but no change in head shape. Increases in predation risk decreased both development and growth rates and slightly reduced relative hind leg length, but there was no change in head shape. Pond desiccation induced quick development and low growth rates, with no changes in morphology. Across environments, both hind leg and head shape plasticity were positively correlated with growth rate plasticity. However, plasticity of developmental rate was only correlated with head shape plasticity. Overall, these results suggest that environmental trends predicted by global warming projections, such as increasing pond temperature and accelerating pond desiccation, will significantly influence hind leg and head morphology in metamorphic frogs, which may affect performance and, ultimately, fitness. KEY WORDS: Morphology · Plasticity · Temperature · Resources · Pond desiccation · Predation risk · Meta-analysis · Global warming Full text in pdf format Supplementary material PreviousNextCite this article as: Tejedo M, Marangoni F, Pertoldi C, Richter-Boix A and others (2010) Contrasting effects of environmental factors during larval stage on morphological plasticity in post-metamorphic frogs. Clim Res 43:31-39. https://doi.org/10.3354/cr00878 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 43, No. 1-2. Online publication date: August 05, 2010 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2010 Inter-Research.

Plastic responses of 4 tree species of successional subalpine coniferous forest serals to different light regimes

Morphological plasticity of ectomycorrhizal (EcM) short roots (known also as first and second order roots with primary development) allows trees to adjust their water and nutrient uptake to local environmental conditions. The morphological traits (MTs) of short-living EcM roots, such as specific root length (SRL) and area, root tip frequency per mass unit (RTF), root tissue density, as well as mean diameter, length, and mass of the root tips, are good indicators of acclimation. We investigated the role of EcM root morphological plasticity across the climate gradient (48–68°N) in Norway spruce (Picea abies (L.) Karst) and (53–66°N) birch (Betula pendula Roth., B. pubescens Ehrh.) forests, as well as in primary and secondary successional birch forests assuming higher plasticity of a respective root trait to reflect higher relevance of that characteristic in acclimation process. We hypothesized that although the morphological plasticity of EcM roots is subject to the abiotic and biotic environmental conditions in the changing climate; the tools to achieve the appropriate morphological acclimation are tree species-specific. Long-term (1994–2010) measurements of EcM roots morphology strongly imply that tree species have different acclimation-indicative root traits in response to changing environments. Birch EcM roots acclimated along latitude by changing mostly SRL [plasticity index (PI) = 0.60], while spruce EcM roots became adjusted by modifying RTF (PI = 0.68). Silver birch as a pioneer species must have a broader tolerance to environmental conditions across various environments; however, the mean PI of all MTs did not differ between early-successional birch and late-successional spruce. The differences between species in SRL, and RTF, diameter, and length decreased southward, toward temperate forests with more favorable growth conditions. EcM root traits reflected root-rhizosphere succession across forest succession stages.

Phenotypic plasticity is one of the important mechanisms relevant to exotic plant invasions, and high plasticity is likely to influence the potential invasiveness of species. Phenotypic plasticity is broadly defined as the ability of organisms to alter their morphological and/or physiological traits in response to varying environments. Morphological and physiological plasticity are thought to have different mechanisms, resource costs and ecological implications. However, our understanding on how morphological and physiological plasticity contribute to invasiveness is still limited. We explored plant growth, morphological and physiological traits to compare the plasticity in response to variations in light availability in phylogenetically related invasive and non-invasive species from South China. We hypothesized that fast-growing and poorly shade-tolerant invasive species may exhibit higher physiological but not morphological plasticity compared with non-invasive species, prompting their successful invasion with variable light resources. On average, the examined invasive species exhibited a higher biomass accumulation under high light conditions than the non-invasive species. The interaction of light and origin had no significant effect on any of the variables in the morphological traits. However, highly significant effects were found in four of the six variables in the physiological traits: the maximum photosynthesis rate, apparent quantum yield, photosynthetic nitrogen use efficiency, and photosynthetic energy use efficiency. In some cases, the invasive species displayed higher physiological but not morphological plasticity than the non-invasive species. However, contrary to the theory, higher overall mean plasticity was not observed in the invasive plants. Our data support the idea that biological invasion is a complicated process and that strong phenotypic plasticity is merely one of the possibilities leading to the successful invasion of exotic plants.

Allowing macroalgae growth forms to emerge: Use of an agent-based model to understand the growth and spread of macroalgae in Florida coral reefs, with emphasis on Halimeda tuna

Ranunculus peltatus Schrank is an aquatic macrophyte spreading in northeastern France. As with other Ranunculus species, its growth demonstrates considerable plasticity. A preliminary understanding of its development and precise adaptive strategy is possible through functional ecology. The present study took morphological traits into account in order to analyse R. peltatus' development and morphological plasticity in relation to environmental parameters. During the five-month growing season, field measurements of ten different morphological traits were performed monthly at twelve sampling sites presenting various physical and chemical characteristics. Three overall growth stages occurred between April and August 2000: a stage of elongation of the main stem, a stage of branching and flowering and a stage of decline associated with vegetative dispersion. The sampling sites were defined according to environmental parameters and divided into three groups corresponding to three morphologically different R. peltatus populations. Plants in upstream, nutrient-poor, undisturbed sites were small and achieved little sexual reproduction. Plants in nutrient-rich, undisturbed sites had long shoots and were branched. Plants in weakly shaded, disturbed sites were small but produced many flowers. Correlations between morphological traits and environmental parameters showed significant relationships between chemical parameters and some characteristic vegetative growth traits. Physical environmental parameters were found to be less well correlated with morphological traits than the chemical parameters. The phenology and morphological plasticity of R. peltatus confer competitive advantages that could explain its ability to spread in some circumstances. Finally, the previous classification of R. peltatus as a Grime CSR species is discussed in relation to its plasticity. According to its morphological characteristics, R. peltatus tended indeed to adopt a C-strategy in nutrient-rich undisturbed sites, a S-strategy in nutrient-poor undisturbed sites and a R-strategy in disturbed sites.

Comparisons between plants and sessile modular colonial invertebrates offer interesting parallelisms between plant and animal body plans after millions of years of divergent evolution. Among these parallelisms might be the existence and distribution of intraindividual heterogeneity in organ traits, also named subindividual variability. Subindividual variability is quantitatively important and has many consequences for plant individuals, populations and communities, and for animal consumers as well. However, could a similar process of subindividual variability occur in sea pens, which have a modular architecture similar to that of plants? In the literature of marine invertebrates very little is known about the presence and magnitude of subindividual variability in modular organisms. This study provides for the first time a quantitative assessment of subindividual variability in sea pens, analysing certain biometric features of reiterated structures that presumably have some ecological function, and offers an initial comparison of quantitative levels of subindividual variation between plants and sea pens.

Background: Brain morphology is a critical trait influencing animal performance that has been shown to demonstrate phenotypic plasticity in response to a variety of environmental cues. Further, plasticity itself has consistently been recognized as a trait that can be selected upon and evolved. Summary: There has been limited research examining how evolution and selection act on plasticity in brain morphology. Here, we review the environmental factors that have been shown to cause plasticity in brain morphology across animal taxa. Key Messages: We further propose a framework for examining the evolution of brain morphology plasticity, including four hypothesized patterns of selection that may cause the evolution of plasticity in this critical trait. Finally, we outline potential ways these hypotheses can be tested to build our understanding of the evolution of brain morphology plasticity.

Within-individual strategies of variation (e.g., phenotypic plasticity) are particularly relevant to modular organisms, in which ramets of the same genetic individual may encounter diverse environments imposing diverse patterns of selection. Hence, measuring selection in heterogeneous environments is essential to understanding whether environment-dependent phenotypic change enhances the fitness of modular individuals. In sublittoral marine habitats, competition for light and space among modular taxa generates extreme patchiness in resource availability. Little is known, however, of the potential for plasticity within individuals to arise from spatially-variable selection in such systems. We tested whether plasticity enhances genet-level fitness in Asparagopsis armata, a clonal seaweed in which correlated traits mediate morphological responses to variation in light. Using the capacity for rapid, clonal growth to measure fitness, we identified aspects of ramet morphology targeted by selection in two contrasting light environments and compared patterns of selection across environments. We found that directional selection on single traits, coupled with linear and nonlinear selection on multi-trait interactions, shape ramet morphology within environments and favor different phenotypes in each. Evidence of environment-dependent, multivariate selection on correlated traits is novel for any marine modular organism and demonstrates that seaweeds, such as A. armata, may potentially adapt to environmental heterogeneity via plasticity in clonal morphology.

An individual's morphology is shaped by the environmental pressures it experiences, and the resulting morphological response is the culmination of both genetic factors and environmental (non-genetic) conditions experienced early in its life (i.e. phenotypic plasticity). The role that phenotypic plasticity plays in shaping phenotypes is important, but evidence for its influence is often mixed. We exposed female neonate diamond-backed watersnakes (Nerodia rhombifer) from populations experiencing different prey-size regimes to different feeding treatments to test the influence of phenotypic plasticity in shaping trophic morphology. We found that snakes in a large-prey treatment from a population frequently encountering large prey exhibited a higher growth rate in body size than individuals in a small-prey treatment from the same population. This pattern was not observed in snakes from a population that regularly encounters small prey. We also found that regardless of treatment, snakes from the small-prey population were smaller at birth than snakes from the large-prey population and remained so throughout the study. These results suggest that the ability to plastically respond to environmental pressures may be population-specific. These results also indicate a genetic predisposition towards larger body sizes in a population where large prey items are more common.

Many organisms can adjust to a changing environment by developing alternative phenotypes that improve their fitness. Our understanding of phenotypic plasticity is largely based upon observations from single species responding to two different environments and measuring a single plastic trait. In this study, I examine predator-induced phenotypic plasticity in tadpoles by observing how six species of larval anurans respond to five different predator environments in 11 different traits (seven morphological traits, two behavioral traits, growth, and development). The results demonstrate that behavioral and morphological plasticity may be ubiquitous in larval anurans. The six prey species exhibited different responses to the same predator species, and each prey exhibited different responses to different predator species. This suggests that responses to a particular predator may not serve as general defense against all predators; rather, prey express predator-specific suites of responses. I also compared relative differences in plasticity among species and among traits. In contrast to earlier findings using only two predator environments, I found that different anurans possess similar degrees of plasticity for most of their traits when reared in a large number of environments. In addition, behavioral traits were always more plastic than morphological traits. Finally, I examined trait integration to address whether there were apparent trade-offs among traits and limits imposed by the abiotic environment. Trait integration, or the degree of correlated responses among traits across predator environments within a prey species, was very low. This further suggests that the suites of responses are predator specific and may be under independent directions of selection in different predator environments. Trait correlations across prey species indicated that there is an apparent trade-off between tail fin depth and body size. This relationship is supported by selection studies within prey species. Relating the responses to the pond permanence habitat gradient over which the amphibians exist, I found that species inhabiting more temporary ponds possess higher general activity levels, shallower tail fins, and larger bodies; these traits are known to result in more rapid growth. In a companion paper, I quantify the predation risk of the 30 predator–prey combinations and examine the relationships between prey response and predation risk.

Morphological and behavioral traits affect an individual’s fitness and can reflect both evolutionary adaptations and phenotypic responses to environmental conditions. We conducted a reciprocal transplant ‘common garden’ experiment at two temperature regimes to test for phenotypic plasticity in morphological and behavioral traits between and within two populations of steelhead Oncorhynchus mykiss from Hood Canal, WA, USA. The Dewatto River and Duckabush River populations exhibited asymmetric changes in body morphology in response to the two temperature regimes, suggesting both between- and within-population variation in morphological plasticity. In most cases, within population variation in body shapes was less than between temperature regimes. Most notably the populations differed in dorso-ventral and caudal regions, body depth, and head shape, with some differences on the anterior-posterior placement of the dorsal and ventral fins. The warm temperature regime caused more exploratory behavior, more charging behavior, and higher fin erosion, and population effects included slight differences in feeding aggression frequency. Morphology appeared to vary more between populations than between temperature regimes, and behavioral traits varied more between temperature regimes than between populations. Morphological variation may reflect adaptations to variation in freshwater habitat conditions, and both populations show behavioral plasticity in response to temperature. This study sheds new light on the role of genetic and environmental influence on morphology and behavior in juvenile steelhead.