Capacity For Phenotypic Plasticity Research Articles

Hypoxia and High Temperature as Interacting Stressors: Will Plasticity Promote Resilience of Fishes in a Changing World?

AbstractDetermining the resilience of a species or population to climate change stressors is an important but difficult task because resilience can be affected both by genetically based variation and by various types of phenotypic plasticity. In addition, most of what is known about organismal responses is for single stressors in isolation, but environmental change involves multiple environmental factors acting in combination. Here, our goal is to summarize what is known about phenotypic plasticity in fishes in response to high temperature and low oxygen (hypoxia) in combination across multiple timescales, to ask how much resilience plasticity may provide in the face of climate change. There are relatively few studies investigating plasticity in response to these environmental stressors in combination; but the available data suggest that although fish have some capacity to adjust their phenotype and compensate for the negative effects of acute exposure to high temperature and hypoxia through acclimation or developmental plasticity, compensation is generally only partial. There is very little known about intergenerational and transgenerational effects, although studies on each stressor in isolation suggest that both positive and negative impacts may occur. Overall, the capacity for phenotypic plasticity in response to these two stressors is highly variable among species and extremely dependent on the specific context of the experiment, including the extent and timing of stressor exposure. This variability in the nature and extent of plasticity suggests that existing phenotypic plasticity is unlikely to adequately buffer fishes against the combined stressors of high temperature and hypoxia as our climate warms.

Evolutionary impacts of winter climate change on insects.

Overwintering is a serious challenge for insects, and winters are rapidly changing as climate shifts. The capacity for phenotypic plasticity and evolutionary adaptation will determine which species profit or suffer from these changes. Here we discuss current knowledge on the potential and evidence for evolution in winter-relevant traits among insect species and populations. We conclude that the best evidence for evolutionary shifts in response to changing winters remain those related to changes in phenology, but all evidence points to cold hardiness as also having the potential to evolve in response to climate change. Predicting future population sizes and ranges relies on understanding to what extent evolution in winter-related traits is possible, and remains a serious challenge.

Effects of Rate of Drying, Life History Phase, and Ecotype on the Ability of the Moss Bryum Argenteum to Survive Desiccation Events and the Influence on Conservation and Selection of Material for Restoration

Desiccation stress is frequently experienced by the moss Bryum argenteum and can influence survival, propagation and niche selection. We attempted to disentangle the interacting factors of life history phase (five categories) and rate of desiccation (time allotted for induction of desiccation tolerance) for thirteen ecotypes of B. argenteum. Using chlorophyll fluorescence as a stress index, we determined how these parameters influenced desiccation tolerance. Rate of drying and life phase significantly affected desiccation tolerance. The reaction norms of desiccation tolerance displayed by the thirteen ecotypes showed a substantial degree of variation in phenotypic plasticity. We observed differences in survival and fluorescence between rapid and slow drying events in juveniles. These same drying applications did not produce as large of a response for adult shoots (which consistently displayed high values). Some juvenile and protonemal ecotypes, such as those from the southwest United States, possessed higher innate tolerance to rapid drying, and greater resilience compared to ecotypes sourced from mesic localities in the United States. These results show a complex nuanced response to desiccation with ecotypes displaying a range of responses to desiccation reflecting both inherently different capacities for tolerating desiccation as well as variation in capacity for phenotypic plasticity. Our results suggest that we should expect few short-term effects of climate change due to high desiccation tolerance of adult shoots, but significant adverse long-term effects on colony establishment due to low tolerance of protonema and juvenile shoots. Further, we would recommend that future studies using mosses for habitat restoration of aridlands consider the desiccation tolerance capacity of individual ecotypes used for cultivation and later re-introduction. Understanding how mosses respond to desiccation is essential to interpret ecological roles, habitat preferences, selective pressures, and responses to climate change, and to estimate the potential effects of climate changes on bryophyte species and populations.

Mussel seed is highly plastic to settling conditions: the influence of waves versus tidal emergence

Phenotypic plasticity is important for organisms to adjust to a new environment. Therefore, the transplantation success of an organism to a new environment can be increased with knowledge of its capacity for phenotypic plasticity in different life stages, and the phenotypic adjustments it needs to make in specific environmental situations. Both the capacity for phenotypic plasticity and the necessary phenotypic adjustments for transplantation were tested in a mesocosm experiment using blue mussels Mytilus edulis as a model organism. This study tested (1) to what extent mussel seed coming from collectors in the water column are still capable of adjusting their phenotype, and (2) whether exposure to air or wave action is more important as a driver of phenotypic adjustments for mussels living in intertidal conditions. We found that mussel seed had a high capacity for phenotypic plasticity, and were capable of adjusting their morphology to accommodate different intertidal hydrodynamic conditions. Exposure to air influenced the shell shape, condition, byssal attachment strength and aggregation behaviour, but exposure to waves played the most important role in determining the phenotype of mussels. Wave-exposed mussels grew bigger, rounder, had thicker shells and a stronger byssal attachment strength than mussels exposed to either calm tidal or calm submerged environments. This knowledge is important for selecting a suitable source population and transplantation location.

An impressive capacity for cold tolerance plasticity protects against ionoregulatory collapse in the disease vector, Aedes aegypti

The mosquito Aedes aegypti is largely confined to tropical and subtropical regions, but its range has recently been spreading to colder climates. As insect biogeography is tied to environmental temperature, understanding the limits of A. aegypti thermal tolerance and their capacity for phenotypic plasticity is important in predicting the spread of this species. In this study, we report on the chill coma onset (CCO) and recovery time (CCRT), as well as low-temperature survival phenotypes of larvae and adults of A. aegypti that developed or were acclimated to 15°C (cold) or 25°C (warm). Cold acclimation did not affect CCO temperatures of larvae but substantially reduced CCO in adults. Temperature and the duration of exposure both affected CCRT, and cold acclimation strongly mitigated these effects and increased rates of survival following prolonged chilling. Female adults were far less likely to take a blood meal when cold acclimated, and exposing females to blood (without feeding) attenuated some of the beneficial effects of cold acclimation on CCRT. Lastly, larvae suffered from haemolymph hyperkalaemia when chilled, but cold acclimation attenuated the imbalance. Our results demonstrate that A. aegypti larvae and adults have the capacity to acclimate to low temperatures, and do so at least in part by better maintaining ion balance in the cold. This ability for cold acclimation may facilitate the spread of this species to higher latitudes, particularly in an era of climate change.

Phenotypic plasticity in morphological features of Thelaxes suberi (Del Guercio, 1911) (Hemiptera: Aphidoidea) feed on Quercus (L.) species

Phenotypic plasticity is a common and important phenomenon in aphids, particularly in host plant utilization. It has been shown that Thelaxes suberi species fed on three closely related Quercus species showed high amount of phenotypic plasticity in morphological characters. Thelaxes suberi population has the largest morphological features on Quercus infectoria and the smallest morphological features on the Quercus coccifera. It was thought that these differences related with the total protein content and level of amino acid in acorns of the host plant where Thelaxes individuals were collected during this study. Findings of the study indicated how high is phenotypic plasticity capacity of aphid species and interactions with host plant properties. Another important implication of the result is that as aphid has a close relationship with host plant and even small amount of changes in the same Quercus species caused that amount of plasticity in Thelaxes species. Recent ecological changes including climatic fluctuations directly influences host plants morphological/nutritional composition and might also impacts the diversity and distribution of aphid species. Findings were also discussed for possible changes in host plant range of the T. suberi as a result of the current phenotypic plasticity and possible interactions between different types of phenotypic plasticities.

Climate adaptation and ecological restoration in eucalypts

Eucalypts are the cornerstone of ecological restoration efforts across the highly modified agricultural landscapes of southern Australia. ‘Local provenancing’ is the established strategy for sourcing germplasm for ecological restoration plantings, yet this approach gives little consideration to the persistence of these plantings under future climates. This paper provides a synopsis of recent and ongoing research that the authors are undertaking on climate adaptation in eucalypts, combining new genomic approaches with ecophysiological evidence from provenance trials. These studies explore how adaptive diversity is distributed within and among populations, whether populations are buffered against change through capacity for phenotypic plasticity, and how this informs provenancing strategies. Results to date suggest that eucalypts have some capacity to respond to future environmental instability through adaptive phenotypic plasticity or selection of putatively adaptive alleles. Despite this, growing evidence suggests that eucalypts will still be vulnerable to change. Provenancing strategies that exploit adaptations found in non-local provenances could thus confer greater climate-resilience in ecological restoration plantings, although they will also need to account for potential interactions between climate adaptations and other factors (e.g. cryptic evolutionary variation, non-climate-related adaptations, herbivory and elevated CO2).

Adaptive evolution of cis‐regulatory regions among genes dynamically expressed in the juvenile human cortex (89.8)

The human brain excels in its capacity for phenotypic plasticity and response to experience. The objective of this study is to investigate the evolutionary history of human brain plasticity. We previously argued that genes that play a role in phenotypic plasticity should respond with a dynamic expression pattern during development, and we reported a set of 304 genes more variably expressed in the juvenile human cortex than adult (Sterner et al., 2012). Changes in how these genes are regulated among humans compared with non‐human primates may provide clues as to the genetic underpinnings of enhanced phenotypic plasticity in the developing human brain. Using publically available genomic data, our approach identified single nucleotides that are differ in humans (e.g. 1000 genomes project) compared to non‐human primates in regions that contain regulatory sequence (i.e., 2kb upstream, first intron, 5’‐ and 3’‐UTR). Thirty‐one out of 304 genes are enriched for regulatory sites that are derived and fixed in humans and also show dynamic expression in the juvenile human cortex (e.g., WAS, KLF4, C1QA, CTSH, PRODH, SERTAD1). Changes in the regulatory responses of these genes may contribute to the evolution of unique aspects of human brain development and plasticity.Grant Funding Source: Supported by NSF [BCS0827546], AAA Post‐doctoral Research Fellowship, and WSU Office VP Research

Life history and morphological plasticity of the soybean aphid, Aphis glycines

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a pest of soybean, Glycine max (L.) Merr. (Fabaceae), from eastern Asia that was first reported in North America in 2000. The influence of temperature on plasticity of life history and morphological traits of the soybean aphid has not been tested despite observable differences in population growth and morphology among isolates in laboratory colonies. Therefore, we used three isolates of the aphid to test whether lifespan, growth rate, fecundity, and morphology were plastic at 16, 24, and 28 °C. Population size of the aphid was influenced by temperature, probably because two reproductive traits, maximum number of offspring in 1 day and total fecundity, were plastic and increased in successive generations at 24 °C. All morphological traits were plastic, including lengths of body parts, number of antennal segments and caudal hairs, and color of siphunculi and body, and they were differentially influenced by isolate and temperature. Knowledge about the life history and morphology of the soybean aphid may help identify its capacity for phenotypic plasticity in heterogeneous temperatures and identify how temperature influences its survival, population growth, and diversity.

Can Phenotypic Plasticity Facilitate the Geographic Expansion of the TilapiaOreochromis mossambicus?

Climate influences the distribution of organisms because of the thermal sensitivity of biochemical processes. Animals may compensate for the effects of variable temperatures, and plastic responses may facilitate radiation into different climates. The tropical fish Oreochromis mossambicus has radiated into climates that were thought to be thermally unsuitable. Here, we test the hypothesis that thermal acclimation will extend the locomotory and metabolic performance range of O. mossambicus. Juvenile fish were acclimated to 14 degrees, 17 degrees, and 22 degrees C. We measured responses to acclimation at three levels of organization: whole-animal performance (sustained swimming and resting and recovery rates of oxygen consumption), mitochondrial oxygen consumption in caudal muscle, and metabolic enzyme activities in muscle and liver at 12 degrees, 14 degrees, 17 degrees, 22 degrees, and 26 degrees C. Thermal optima of sustained swimming performance (U(crit)) changed significantly with acclimation, but acclimation had no effect on either resting or recovery oxygen consumption. Fish compensated for cold temperatures by upregulating state 3 mitochondrial oxygen consumption and increasing activity of lactate dehydrogenase in the liver. The capacity for phenotypic plasticity in O. mossambicus means that the fish would not be limited by its locomotor performance or metabolic physiology to expand its range into cooler thermal environments from its current distribution.