Little evidence for morphological change in a resilient endemic species following the introduction of a novel predator

Human activities, such as species introductions, are dramatically and rapidly altering natural ecological processes and often result in novel selection regimes. To date, we still have a limited understanding of the extent to which such anthropogenic selection may be driving contemporary phenotypic change in natural populations. Here, we test whether the introduction of the piscivorous Nile perch, Lates niloticus, into East Africa's Lake Victoria and nearby lakes coincided with morphological change in one resilient native prey species, the cyprinid fish Rastrineobola argentea. Drawing on prior ecomorphological research, we predicted that this novel predator would select for increased allocation to the caudal region in R. argentea to enhance burst-swimming performance and hence escape ability. To test this prediction, we compared body morphology of R. argentea across space (nine Ugandan lakes differing in Nile perch invasion history) and through time (before and after establishment of Nile perch in Lake Victoria). Spatial comparisons of contemporary populations only partially supported our predictions, with R. argentea from some invaded lakes having larger caudal regions and smaller heads compared to R. argentea from uninvaded lakes. There was no clear evidence of predator-associated change in body shape over time in Lake Victoria. We conclude that R. argentea have not responded to the presence of Nile perch with consistent morphological changes and that other factors are driving observed patterns of body shape variation in R. argentea

Where less may be more: how the rare biosphere pulls ecosystems strings

Rare species are increasingly recognized as crucial, yet vulnerable components of Earth’s ecosystems. This is also true for microbial communities, which are typically composed of a high number of relatively rare species. Recent studies have demonstrated that rare species can have an over-proportional role in biogeochemical cycles and may be a hidden driver of microbiome function. In this review, we provide an ecological overview of the rare microbial biosphere, including causes of rarity and the impacts of rare species on ecosystem functioning. We discuss how rare species can have a preponderant role for local biodiversity and species turnover with rarity potentially bound to phylogenetically conserved features. Rare microbes may therefore be overlooked keystone species regulating the functioning of host-associated, terrestrial and aquatic environments. We conclude this review with recommendations to guide scientists interested in investigating this rapidly emerging research area

Locally Extreme Environments as Natural Long-Term Experiments in Ecology

Many natural phenomena and ecological processes take place extremely slowly, requiring both long-term observations and experiments to investigate them. An alternative is to investigate natural systems that have long-term and stable environmental conditions that are opposed to those of the surrounding ecosystem. Locally extreme environments provide an example of this, and are a powerful tool for the study of slower ecological and evolutionary processes, allowing the investigation of longer term mechanisms at logistically tractable spatial and temporal scales. These systems can be used to gain insight into adaptation of natural communities and their ecological networks. We present a case study and review the literature investigating biological communities at terrestrial mofettes—natural sites with constant geogenic CO2 exhalations and consequent soil hypoxia. Mofettes are often used as natural analogues to future conditions predicted by current climate change scenarios, as model ecosystems for environmental impact assessments of carbon capture and storage systems and for the investigation of physiological, ecological and evolutionary studies of a range of phylogenetically distinct organisms across spatial scales. The scientific power of locally extreme environments is just starting to be harnessed and these systems are bound to provide growing insight into long-term ecological processes, which will be essential for our capacity to adequately manage ecosystems and predict ecological and evolutionary responses to global change

Data from: Long-term culture at elevated atmospheric CO2 fails to evoke specific adaptation in seven freshwater phytoplankton species

The concentration of CO2 in the atmosphere is expected to double by the end of the century. Experiments have shown that this will have important effects on the physiology and ecology of photosynthetic organisms, but it is still unclear if elevated CO2 will elicit an evolutionary response in primary producers that causes changes in physiological and ecological attributes. In this study, we cultured lines of seven species of freshwater phytoplankton from three major groups at current (approx. 380 ppm CO2) and predicted future conditions (1000 ppm CO2) for over 750 generations. We grew the phytoplankton under three culture regimes: nutrient-replete liquid medium, nutrient-poor liquid medium and solid agar medium. We then performed reciprocal transplant assays to test for specific adaptation to elevated CO2 in these lines. We found no evidence for evolutionary change. We conclude that the physiology of carbon utilization may be conserved in natural freshwater phytoplankton communities experiencing rising atmospheric CO2 levels, without substantial evolutionary change

Asymmetric migration decreases stability but increases resilience in a heterogeneous metapopulation

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The effects of elevated atmospheric CO₂ on freshwater periphyton in a temperate stream

This study examines the effects of elevated CO 2 on the benthic biology of a temperate freshwater stream. We tested the hypotheses that elevated CO 2 would increase periphyton biomass, alter elemental composition, and change community composition by increasing the frequency of algal taxa most limited by CO 2 availability. Carbon dioxide was bubbled into reservoirs of stream water, increasing the ambient pCO 2 by approximately 1100 ppm. The CO 2 -enriched water then flowed into artificial stream channels. Ceramic tiles were placed into the channels to allow for periphyton colonization. Dissolved inorganic carbon increased and pH decreased with added CO 2 . Measurements of biological parameters including periphyton biomass, algal C:N:P ratios, and community composition suggest that the periphyton were unaffected by the changes in stream water chemistry. We infer that rising atmospheric CO 2 will impact stream water chemistry but that periphyton may not be the first to respond to these changes. Impacts to alkaline freshwater streams from elevated CO 2 initially may be due to changes to terrestrial inputs that affect microbial decomposition and grazer activity, rather than through increases in periphyton carbon fixation. However, environmental characteristics of freshwater systems vary considerably, and additional studies are needed for accurate predictive modeling and monitoring of the effects of increasing atmospheric CO 2 on freshwater streams