Pre-exposure to simultaneous,but not individual,climate change stressors limits acclimation capacity of Irukandji jellyfish polyps to predicted climate scenarios

Researchers have investigated the immediate effects of end-of-century climate change scenarios on many marine species, yet it remains unclear whether we can reliably predict how marine species may respond to future conditions because biota may become either more or less resistant over time. Here, we examined the role of pre-exposure to elevated temperature and reduced pH in mitigating the potential negative effects of future ocean conditions on polyps of a dangerous Irukandji jellyfish Alatina alata. We pre-exposed polyps to elevated temperature (28 °C) and reduced pH (7.6), in a full factorial experiment that ran for 14 d. We secondarily exposed original polyps and their daughter polyps to either current (pH 8.0, 25 °C) or future conditions (pH 7.6, 28 °C) for a further 34 d to assess potential phenotypic plastic responses and whether asexual offspring could benefit from parental pre-exposure. Polyp fitness was characterised as asexual reproduction, respiration, feeding, and protein concentrations. Pre-exposure to elevated temperature alone partially mitigated the negative effects of future conditions on polyp fitness, while pre-exposure to reduced pH in isolation completely mitigated the negative effects of future conditions on polyp fitness. Pre-exposure to the dual stressors, however, reduced fitness under future conditions relative to those in the control treatment. Under future conditions, polyps had higher respiration rates regardless of the conditions they were pre-exposed to, suggesting that metabolic rates will be higher under future conditions. Parent and daughter polyps responded similarly to the various treatments tested, demonstrating that parental pre-exposure did not confer any benefit to asexual offspring under future conditions. Importantly, we demonstrate that while pre-exposure to the stressors individually may allow Irukandji polyps to acclimate over short timescales, the stressors are unlikely to occur in isolation in the long term, and thus, warming and acidification in parallel may prevent polyp populations from acclimating to future ocean conditions.

     

Irukandji jellyfish polyps exhibit tolerance to interacting climate change stressors

Increasing ocean temperatures and strengthening boundary currents have caused the poleward migration of many marine species. Cubozoan jellyfish known to cause Irukandji syndrome have historically been confined to tropical waters but may be expanding into subtropical regions. Here, we examine the interactive effects of warming and acidification on the population dynamics of polyps of an Irukandji jellyfish, Alatina nr mordens, and the formation of statoliths in newly metamorphosed medusae, to determine if this jellyfish could tolerate future conditions predicted for southeast Queensland (SEQ), Australia. Two experiments, examining the orthogonal factors of temperature and pH, were undertaken. Experiment 1 mimicked the current, ca. 2050 and ca. 2100 summer temperature and pH conditions predicted for SEQ using A1F1 scenarios (temperature: 25, 27, 29 °C; pH: 7.9, 7.8, 7.6) and Experiment 2 mimicked current and future winter conditions (18 and 22 °C, pH 7.9, 7.8, 7.6). All polyps in Experiment 1 survived and budded. Fewer polyps budded in the lower pH treatments; however, patterns varied slightly among temperature treatments. Statoliths at pH 7.6 were 24% narrower than those at pH 7.8 and 7.9. Most polyps survived the winter conditions mimicked by Experiment 2 but only polyps in the 22 °C, pH 7.9 treatment increased significantly. The current absence of A. nr mordens medusae in SEQ, despite the polyps' ability to tolerate the current temperature and pH conditions, suggests that ecological, rather than abiotic factors currently limit their distribution. Observations that budding was lower under low pH treatments suggest that rates of asexual reproduction will likely be much slower in the future. We consider that A. nr mordens polyps are likely to tolerate future conditions but are unlikely to thrive in the long term. However, if polyps can overcome potential ecological boundaries and acidification proceeds slowly A. nr mordens could expand polewards in the short term.     

Risk of spring frost to apple production under future climate scenarios: the role of phenological acclimation

In the context of global warming, the general trend towards earlier flowering dates of many temperate tree species is likely to result in an increased risk of damage from exposure to frost. To test this hypothesis, a phenological model of apple flowering was applied to a temperature series from two locations in an important area for apple production in Europe (Trentino, Italy). Two simulated 50-year climatic projections (A2 and B2 of the Intergovernmental Panel on Climate Change - Special Report on Emission Scenarios) from the HadCM3 general circulation model were statistically downscaled to the two sites. Hourly temperature records over a 40-year period were used as the reference for past climate. In the phenological model, the heat requirement (degree hours) for flowering was parameterized using two approaches; static (constant over time) and dynamic (climate dependent). Parameterisation took into account the trees’ adaptation to changing temperatures based on either past instrumental records or the downscaled outputs from the climatic simulations. Flowering dates for the past 40 years and simulated flowering dates for the next 50 years were used in the model. A significant trend towards earlier flowering was clearly detected in the past. This negative trend was also apparent in the simulated data. However, the significance was less apparent when the “dynamic” setting for the degree hours requirement was used in the model. The number of frost episodes and flowering dates, on an annual basis, were graphed to assess the risk of spring frost. Risk analysis confirmed a lower risk of exposure to frost at present than in the past, and probably either constant or a slightly lower risk in future, especially given that physiological processes are expected to acclimate to higher temperatures. An erratum to this article can be found at     

Modelling the predicted geographic and economic response of UK cropping systems to climate change scenarios: the case of potatoes

Geographical changes in suitability in England and Wales for the cultivation of potatoes under a climate change scenario were predicted for the years 2023 and 2065 by integrating a climate database (1951-80) with climate-driven crop growth models. Initially, model outputs were produced as point values (meteorological site locations) of predicted potential yields for current crop production. The model outputs were validated statistically using actual crop yield figures collated from bibliographic analysis. The most suitable model was run again incorporating projected temperature and precipitation changes for 2023 and 2065. These outputs were then used to predict possible economic changes to farm profitability and general market trends. Results indicated that, although yields may rise, gross margins for maincrop and especially early potatoes may also rise due to shifts in production, to a fall in overall potato output and to price increases.     

Modelling the predicted geographic and economic response of UK cropping systems to climate change scenarios: the case of sugar beet

Geographical changes in suitability for the cultivation of sugar beet in England and Wales were predicted for climate change scenarios for 2023 and 2065 by integrating a climate database (1951-80) with climate-driven crop growth models. Initially, the outputs were produced as point values (at meteorological site locations) of predicted potential yields for current production. The outputs were validated statistically using actual crop yield figures collated from bibliographic analysis. The most suitable model was run again incorporating projected temperature and precipitation changes for 2023 and 2065. The outputs were mapped using a Geographical Information System and used to predict possible economic changes in farm profitability (and general market trends). Results indicated that the area of suitability for the growth of the crop moves westward with an increase in production in the West Midlands of approximately 5% (2 t ha^-1 fresh weight) by 2023 and 13% (6 t ha^-1 fresh weight) by 2065. The reduction in production in East Anglia coupled with the increase in production in the West does not align well with the current location of processing factories     

Some like it hot and some like it cold,but not too much: plant responses to climate extremes

Current climatic models predict increasing frequency and magnitude of extreme climatic events (ECEs). Ecological studies recognize the importance of these extremes as drivers of plant growth and mortality, as well as drivers of ecological and evolutionary processes. Here we review observational and experimental studies on ECEs on herbaceous plants and shrubs. Extreme events considered were heat waves, drought, advanced or delayed snowmelt, heavy rainfalls, frosts, pulsed watering and flooding. We analysed 39 studies dealing with direct response of plant to ECEs in different ecosystems, with a particular focus on cold ecosystems (alpine and arctic). Although the number of studies increases every year, the understanding of ecological consequences of ECEs is fragmentary. In general, ECEs affected negatively on physiological processes (efficiency of photosystem II, stomatal conductance and leaf water potential), productivity and reproduction, and had consequences on population demography and recruitment several years after ECE. Indeed, the plant responses to ECEs were species specific and depended on the plant life stage and the timing of ECE. In fact, the magnitude of the effect of ECEs decreased over the growing season. Drought had the most severe effect on plants, while heat waves had minor effect if water was available. The overlap of different ECEs had an additive effect (e.g. drought associated to heat-waves). In general, both neutral or positive plant responses were found and acclimation is possible. In some cases, ECEs exert a strong selective pressure on plant species.     

Telomerase can extend the proliferative capacity of human myoblasts,but does not lead to their immortalization

Normal cells in culture display a limited capacity to divide and reach a non-proliferative state called cellular senescence. Spontaneous escape from senescence resulting in an indefinite life span is an exceptionally rare event for normal human cells and viral oncoproteins have been shown to extend the replicative life span but not to immortalize them. Telomere shortening has been proposed as a mitotic clock that regulates cellular senescence. Telomerase is capable of synthesizing telomere repeats onto chromosome ends to block telomere shortening and to maintain human fibroblasts in proliferation beyond their usual life span. However, the consequence of telomerase expression on the life span of human myoblasts and on their differentiation is unknown. In this study, the telomerase gene and the puromycin resistance gene were introduced into human satellite cells, which are the natural muscle precursors (myoblasts) in the adult and therefore, a target for cell-mediated gene therapy. Satellite cells expressing telomerase were selected, and the effects of the expression of the telomerase gene on proliferation, telomere length, and differentiation were investigated. Our results show that the telomerase-expressing cells are able to differentiate and to form multinucleated myotubes expressing mature muscle markers and do not form tumors in vivo. We also demonstrated that the expression of hTERT can extend the replicative life of muscle cells although these failed to undergo immortalization.     

Seed provenance for changing climates: early growth traits of nonlocal seed are better adapted to future climatic scenarios,but not to current field conditions

The urgency to repair degraded ecosystems is challenged by the need to future‐proof populations to deal with changing climates. Therefore, it is necessary to know if source gene‐pools are resilient to both current and future climatic conditions. We tested this question with the pioneer shrub Hardenbergia violacea (Fabaceae), an important species for restoration in eastern Australia. We evaluated in situ and ex situ performance of seed from eight provenances, two local and six from regions receiving hotter and wetter spring to autumn conditions and/or drier winters and we included wild and commercial collections. We compared survivorship of seedlings in climate‐houses that emulated current and predicted temperature and rainfall. In the field, we measured germination and seedling survivorship. We used neutral codominant markers to provide inbreeding and heterozygosity estimates to evaluate against health and survivorship. All provenances survived the current conditions, but local provenances were the poorest performers in the predicted hotter and wetter scenario compared with nonlocal provenances. No provenance survived more than a fortnight of a climate‐house simulated, but predicted, extreme weather event of a drought (35/22°C 12 hours day/night, 50 mL/week = 220 mm rainfall). Heterozygosity was positively associated with plant health in surviving plants, and plants in poor condition had high inbreeding estimates. In the field, nonlocal provenances performed poorly and most survivors were from local provenances. The contribution of individual genetic variation to stress tolerance will be an important consideration when selecting provenances for future climates.     

Topographic,latitudinal and climatic distribution of Pinus coulteri: geographic range limits are not at the edge of the climate envelope

With changing climate, many species are projected to move poleward or to higher elevations to track suitable climates. The prediction that species will move poleward assumes that geographically marginal populations are at the edge of the species' climatic range. We studied Pinus coulteri from the center to the northern (poleward) edge of its range, and examined three scenarios regarding the relationship between the geographic and climatic margins of a species' range. We used herbarium and iNaturalist.org records to identify P. coulteri sites, generated a species distribution model based on temperature, precipitation, climatic water deficit, and actual evapotranspiration, and projected suitability under future climate scenarios. In fourteen populations from the central to northern portions of the range, we conducted field studies and recorded elevation, slope and aspect (to estimate solar insolation) to examine relationships between local and regional distributions. We found that northern populations of P. coulteri do not occupy the cold or wet edge of the species' climatic range; mid‐latitude, high elevation populations occupy the cold margin. Aspect and insolation of P. coulteri populations changed significantly across latitudes and elevations. Unexpectedly, northern, low‐elevation stands occupy north‐facing aspects and receive low insolation, while central, high‐elevation stands grow on more south‐facing aspects that receive higher insolation. Modeled future climate suitability is projected to be highest in the central, high elevation portion of the species range, and in low‐lying coastal regions under some scenarios, with declining suitability in northern areas under most future scenarios. For P. coulteri, the lack of high elevation habitat combined with a major dispersal barrier may limit northward movement in response to a warming climate. Our analyses demonstrate the importance of distinguishing geographically vs. climatically marginal populations, and the importance of quantitative analysis of the realized climate space to understand species range limits.     

Erratum to: The original online version of the following articles was revised: the issue date is not January 2020, but January 2021

Journal of Evolutionary Biochemistry and Physiology - A Correction to this paper has been published: https://doi.org/10.1134/S0022093021020216     

Erratum to: Loss of heterophylly in aquatic plants: not ABA-mediated stress but exogenous ABA treatment induces stomatal leaves in Potamogeton perfoliatus

Journal of Plant Research -     

Simulation of biological evolution under attack,but not really: a response to Meester

The leading Intelligent Design theorist William Dembski (Rowman & Littlefield, Lanham MD, 2002) argued that the first No Free Lunch theorem, first formulated by Wolpert and Macready (IEEE Trans Evol Comput 1: 67–82, 1997), renders Darwinian evolution impossible. In response, Dembski’s critics pointed out that the theorem is irrelevant to biological evolution. Meester (Biol Phil 24: 461–472, 2009) agrees with this conclusion, but still thinks that the theorem does apply to simulations of evolutionary processes. According to Meester, the theorem shows that simulations of Darwinian evolution, as these are typically set in advance by the programmer, are teleological and therefore non-Darwinian. Therefore, Meester argues, they are useless in showing how complex adaptations arise in the universe. Meester uses the term “teleological” inconsistently, however, and we argue that, no matter how we interpret the term, a Darwinian algorithm does not become non-Darwinian by simulation. We show that the NFL theorem is entirely irrelevant to this argument, and conclude that it does not pose a threat to the relevance of simulations of biological evolution.