COMPARATIVE ECOPHYSIOLOGY OF NATIVE AND INVASIVE PLANTS ACROSS POPULATIONS, SPECIES, AND CONTINENTS

Invasive species are a persistent threat to biodiversity and agriculture that cost countries millions of dollars each year. Despite the scale and impact of the problem of invasive species, it remains a mystery why some introduced species become invasive and others remain benign. Here, I examined the theory that invasive species possess key traits which make them successful invaders. Specifically, I investigated the hypotheses that 1) plasticity increases invasive species’ success compared to native species, 2) invaders evolve rapidly in their new ranges, 3) invasive species avoid tradeoffs apparent in natives related to growth, resource use, or defense. Using 30 species of native and invasive shade tolerant shrub species in a common garden, I tested whether invasive species had leaf traits that were more plastic to seasonal changes in light availability. I found that invasive species were more plastic, but I found no evidence that their plasticity contributed to increased carbon assimilation across the growing season. Next, I compared leaf traits of populations of five invasive species growing in forests from East Asia in their native range (Japan) and their invasive range (Eastern North America). I also compared these five invaders to three native co-occurring North American species. I selected individuals that occurred along a natural light gradient to assess leaf plasticity in response to light availability. I determined that plasticity in invaders partially arose in the native range, and that some plasticity evolved rapidly in the invaded range after introduction. I concluded that many North American species are less adapted for life in high light environments, such as along forest edges, than East Asian invaders; the ability to grow in both low and high-light conditions may give some forest invaders a competitive advantage. Finally, I quantified traits of annual, perennial, coastal salt tolerant perennials, and invasive populations of Mimulus guttatus in a greenhouse setting (22 total populations). I decomposed relative growth rates of each group into specific leaf area, photosynthetic rate, and leaf mass fraction to determine which trait contributed most to growth rate within each group of populations. Invasive populations did not have higher relative growth rates, contrary to our predictions, but they did have different ways of achieving high growth rates. I also examined whether tradeoffs associated with global trait patterns such as the leaf economics spectrum apply at the population level. I found that global patterns of plant functional traits may not be applicable when studying traits within species. I conclude that a variety of traits and evolutionary history contribute to the success of invasive species around the globe

Time series genome-centric analysis unveils bacterial response to operational disturbance in activated sludge

Understanding ecosystem response to disturbances and identifying the most critical traits for the maintenance of ecosystem functioning are important goals for microbial community ecology. In this study, we used 16S rRNA amplicon sequencing and metagenomics to investigate the assembly of bacterial populations in a full-scale municipal activated sludge wastewater treatment plant over a period of 3 years, including a 9-month period of disturbance characterized by short-term plant shutdowns. Following the reconstruction of 173 metagenome-assembled genomes, we assessed the functional potential, the number of rRNA gene operons, and the in situ growth rate of microorganisms present throughout the time series. Operational disturbances caused a significant decrease in bacteria with a single copy of the rRNA (rrn) operon. Despite moderate differences in resource availability, replication rates were distributed uniformly throughout time, with no differences between disturbed and stable periods. We suggest that the length of the growth lag phase, rather than the growth rate, is the primary driver of selection under disturbed conditions. Thus, the system could maintain its function in the face of disturbance by recruiting bacteria with the capacity to rapidly resume growth under unsteady operating conditions.Fil: Pérez, María Victoria. Agua y Saneamientos Argentinos S.a.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Guerrero, Leandro Demián. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Orellana, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Figuerola, Eva Lucia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Erijman, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentin

Influence of climate change and variability on Coffea arabica in the East African highlands

A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy (Agroclimatology) at the University of Witwatersrand, 2017.Plant development is inherently linked to meteorological variability. The phenology, distribution and production of crops and wild relatives has already altered in response to climate change. Recent years have produced the warmest mean annual global temperatures since 1880, with 2016 setting the highest record thus far. Such profound changes have sparked investigations into the impact of temperature and rainfall on crop development, particularly those with profound economic importance such as coffee (C. arabica). The crop is a fundamental source of income for smallholder farming communities and governments throughout the tropical highlands. However, the impact of climate change on C. arabica has yet to be quantified using empirical data in East Africa, leaving uncertainty in the cultivable future of the crop. Therefore, the objective of this thesis is to investigate the influence of climate change and variability on C. arabica yields and phenology in East Africa. Using a spatio-temporal approach, trends and relationships between coffee performance and meteorological variables were analysed at different scales and time periods ranging from the macroclimatic national scale (49 year), to the meso- and microclimatic farm level (3 year) scale, and finally to the microclimatic canopy and leaf level (hourly) scales. Data from all three climatic continua reveal for the first time that temperatures, and particularly rapidly advancing night time temperatures, are having a substantial negative impact on C. arabica yields. Forecasting models based on these biophysical relationships indicate that by the year 2050, smallholder farmers would on average harvest approximately 50% of the yield they are achieving today. Warming night time temperatures are also responsible for advancing ripening and harvest phenology. As a result, bean filling and development time is reduced, thereby potentially resulting in lower quality coffee. Trends in precipitation do not appear to have any substantial impact on C. arabica yields or harvest phenology, however, it is proposed that rainfall would act synergistically with temperatures to influence plant development and other phenological phases such as flowering. Finally, thermography is introduced as a novel complementary technique to rapidly analyse the suitability of different agroecological systems on coffee physiology at the leaf level. High temporal resolution (hourly) data, illustrate the success of the method in variable meteorological and environmental conditions. The findings contribute to advancing the protocol for use at the canopy and plantation level on coffee, so that appropriate microenvironment designs and adaptation mechanisms be put in place to accommodate climatic change. Avoiding increments in night time temperatures is key to maintaining or improving yields and fruiting development. Farming at higher altitudes and novel agroforestry systems may assist in achieving lower night time temperatures. Importantly, data reveal that careful analysis of various cropping systems, particularly at lower altitudes, is critical for providing suitable microenvironments for the crop.XL201

Ecophysiological diversity of wild<i> Coffea arabica</i> populations in Ethiopia : Drought adaptation mechanisms

Drought is a wide-spread limiting factor in coffee (Coffea arabica L.) production, but the development of adapted cultivars is hampered by a limited understanding of the physiological resistance mechanism and the extreme narrow genetic base of plant material used in breeding. Therefore, the objective of this study was to evaluate the ecophysiological diversity of coffees wild progenitors and their potential for the improvement of drought resistance at its primary gene pool and center of genetic diversity, in Ethiopia. Complementary field and common-garden studies of populations native to habitats spanning a wide range of climatic conditions were examined by combining seasonal measurements in naturally regenerated stands of wild coffee (in-situ) with an artificial drought stress experiment (ex-situ), where seedlings of these populations were raised under controlled environmental conditions and subjected to different watering and light intensity regimes. Plant ecophysiological behavior was assessed in terms of gas exchange activity, leaf water status determined by water potential and osmotic potential measurements, chlorophyll fluorescence and carbon isotope discrimination. The results of both experiments revealed that the ecophysiology of wild C. arabica populations was strongly influenced by conditions of water deficit, heat and high irradiance, which had combined effects on the plants during drought periods. However, the coffee plants were able to adapt to the natural and experimental drought conditions; thereby their resistance mechanism was mainly based on the capability to avoid tissue desiccation. In particular, physiological responses were attributed to fine control of stomatal conductance reducing water loss, high rates of photosynthesis and improved water-use efficiency. Overnight re-saturation of tissue water status with no active osmotic adjustment ability was another important characteristic in drought adaptation of the plants. In addition, the in-situ ecophysiological behavior of populations from different habitats revealed contrasting strategies in response to drought stress, thereby this habitat-specific variability was also found under common-garden conditions. Thus, the results of this study provide evidence that there is a genetic basis of the marked ecophysiological diversity in wild Coffea arabica and that the contrasting habitat conditions result into different selection pressures for traits related to water-use and promote regional differentiation in adaptation to drought stress. Furthermore, the coffee plants exhibited substantial phenotypic plasticity for all ecophysiological traits in response to varying soil moisture conditions; thereby the magnitude of plasticity differed markedly among the populations. In particular, plants originating from drier, variable climates showed the highest amount of plasticity suggesting fast adaptation to changing environmental conditions. A high correlation of plastic responses in most characters was an indicator for a high degree of phenotypic integration demonstrating the need for integrative approaches for the evaluation of drought adaptation in this species. Overall, the profound amount of ecophysiological diversity in the primary gene pool of C. arabica found in this study emphasizes its importance as a unique and valuable genetic resource. The specific adaptations to drought stress suggest a high potential for breeding of improved cultivars and stresses the need for conservation of the profound ecophysiological diversity. In particular, the findings suggest an approach of in-situ conservation within the evolutionary dynamic ecosystems of the natural habitat of Coffea arabica in order to allow the preservation of genes for stress resistance as they co-evolve with their changing environment.Ökophysiologische Diversität in Wildpopulationen von Coffea arabica in Äthiopien - Mechanismen der Trockenstreßadaption Trockenstress gehört weltweit zu den Umweltfaktoren, die im erheblichen Maße das Ertragspotenzial von Arabica-Kaffee (Coffea arabica L.) beeinträchtigen. Da jedoch die Züchtung stressadaptierter Sorten durch mangelnde Kenntnisse des Resistenzmechanismus sowie der engen genetischen Basis moderner Kulturpflanzen stark limitiert ist, untersucht die vorliegende Arbeit das Ausmaß der ökophysiologischen Vielfalt und Züchtungs-potenzial von Arabica-Kaffee in Äthiopien, seinem Ursprung und genetischem Zentrum. Hierzu wurden vier Fragmente des afromontanen Regenwaldes mit natürlichem Vorkommen von Arabicakaffee entlang eines Klimagradienten ausgewählt und das ökophysiologische Verhalten der Pflanzen während natürlich vorkommender Trockenperioden am natürlichen Standort (in-situ) sowie unter kontrollierten Trockenstressbedingungen (ex-situ) untersucht. Die Charakterisierung des pflanzlichen Wasserhaushaltes erfolgte durch Messungen des Gaswechsels, der Chlorophyll-Fluoreszenz, des Blattwasserstatus sowie der δ13C Analyse. Sowohl unter natürlichen als auch unter experimentellen Trockenstressbedingungen war das ökophysiologische Verhalten der Kaffeepflanzen stark von einer Kombination verschiedener Umweltfaktoren wie Bodenwassergehalt, Temperatur, Lichtintensität und dem atmosphärischen Wasserdampfdruckdefizit beeinflusst. An der Ausprägung der Trockenstressresistenz zeigten sich eine Vielzahl von physiologischen Merkmalen beteiligt, die vornehmlich auf Mechanismen zur Vermeidung der Austrocknung des Pflanzengewebes beruhten, wobei eine mögliche Austrocknungs-toleranz durch osmotische Anpassung nicht nachgewiesen werden konnte. Eine Anpassung an Trockenheit erreichten die Pflanzen maßgeblich durch das Aufrechterhalten einer hohen Nettophotosyntheserate, die effektive stomatäre Kontrolle der Transpirationsverluste sowie eine hohe Wasserausnutzungseffizienz. Weiterhin zeigten die Ergebnisse, dass sich die Kaffeepopulationen hinsichtlich der Anpassung an Trockenstress unterschieden, wobei die Ausprägung unter ex-situ Bedingungen auf eine genetische Fixierung der populationsspezifischen Adapations-mechanismen hinweist. Da sich die Unterschiede darüber hinaus als Anpassung an die jeweiligen Umweltbedingungen am natürlichen Standort interpretieren ließen, kann den spezifischen Habitatbedingungen als Selektionsfaktoren eine bedeutende Rolle hinsichtlich der ökophysiologischen Differenzierung der Populationen beigemessen werden. Weiterhin stellt die Arbeit die phänotypische Plastizität als eine wichtige Anpassungs-strategie in den äthiopischen Kaffeepopulationen an veränderte Umweltbedingungen heraus, hinsichtlich dieser auch Populationsunterschiede nachgewiesen werden konnten. Darüber hinaus verdeutlichten die Ergebnisse die Notwendigkeit einer integrierten Betrachtungsweise der untersuchten ökophysiologischen Merkmale, die in Ihrem Zusammenwirken maßgeblich die erfolgreiche Adaptation an Trockenstress beeinflussen. Die in dieser Studie nachgewiesene einmalige ökophysiologische Vielfalt der äthiopischen Wildkaffeepopulationen belegt ihren potenziellen Nutzen in Züchtungsprogrammen und macht somit die Erarbeitung nachhaltiger Schutzkonzepte für den Erhalt dieser wertvollen pflanzengenetischen Ressourcen notwendig. Hierbei sollten Strategien einer In-situ-Konservierung im Vordergrund stehen, um so den Erhalt und die kontinuierliche Weiterentwicklung der ökophysiologischen Diversität von C. arabica für heutige und auch zukünftige Nutzungsinteressen gewährleisten zu können

Review: Challenges for dairy cow production systems arising from climate changes.

The so-called global change refers to changes on a planetary scale. The term encompasses various issues like resource use, energy development, population growth, land use and land cover, carbon and nitrogen cycle, pollution and health, and climate change. The paper deals with challenges for dairy cattle production systems in Europe arising from climate change as one part of global changes. Global warming is increasing, and therefore ecosystems, plant and animal biodiversity, and food security and safety are at risk. It is already accepted knowledge that the direct and indirect effects of global warming in combination with an increasing frequency of weather extremes are a serious issue for livestock production, even in moderate climate zones like Central Europe. The potential and already-measurable effects of climate change (including increase in temperature, frequency of hot days and heat waves), in particular the challenges on grassland production, fodder quality, nutrition in general, cow welfare, health as well as performance of dairy production, will be reviewed. Indirect and direct effects on animals are correlated with their performance. There are clear indications that with selection for high-yielding animals the sensitivity to climate changes increases. Cumulative effects (e.g. higher temperature plus increased pathogen and their vectors loads) do strengthen these impacts. To cope with the consequences several possible adaptation and mitigation strategies must be established on different levels. This includes changes in the production systems (e.g. management, barn, feeding), breeding strategies and health management

Modeling heat stress under organic dairy farming conditions in warm temperate climates within the Mediterranean basin

We studied the effect of heat stress on milk quality in Spanish organic dairy farms using published milk productivity equations. We collected data from 23 weather stations and 14,424 milk test-days for milk yield and milk fat and protein content for the period July 2011 to June 2013. As an indicator of heat stress, we used the maximum daily temperature–humidity index (THI) from 2 days before the milk test date. We fitted the data using hierarchical regression models stratified by farm, cow parity and monthly testday milk records. The effect of THI was deemed low on biological costs through milk yield. However, the known negative relationship between milk yield and milk quality (protein and fat content) became even steeper when the THI increased, suggesting a significant negative correlation between heat stress and milk quality. Therefore, although the milk yield of cows in the organic farming systems analyzed appeared resilient to heat stress conditions, milk quality, a major selling point for organic dairy products, was negatively affected. The model presented here could be used to predict the potential impacts of different climate change scenarios on dairy farming, and to delineate adaptation strategies within organic systems.info:eu-repo/semantics/publishedVersio

Maize open-pollinated populations physiological improvement: validating tools for drought response participatory selection

Participatory selection—exploiting specific adaptation traits to target environments—helps to guarantees yield stability in a changing climate, in particular under low-input or organic production. The purpose of the present study was to identify reliable, low-cost, fast and easy-to-use tools to complement traditional selection for an e ective participatory improvement of maize populations for drought resistance/tolerance. The morphological and eco-physiological responses to progressive water deprivation of four maize open-pollinated populations were assessed in both controlled and field conditions. Thermography and Chl a fluorescence, validated by gas exchange indicated that the best performing populations under water-deficit conditions were ‘Fandango’ and to a less extent ‘Pigarro’ (both from participatory breeding). These populations showed high yield potential under optimal and reduced watering. Under moderate water stress, ‘Bilhó’, originating from an altitude of 800 m, is one of the most resilient populations. The experiments under chamber conditions confirmed the existence of genetic variability within ‘Pigarro’ and ‘Fandango’ for drought response relevant for future populations breeding. Based on the easiness to score and population discriminatory power, the performance index (PIABS) emerges as an integrative phenotyping tool to use as a refinement of the common participatory maize selection especially under moderate water deprivationinfo:eu-repo/semantics/publishedVersio

Can artificial habitat mitigate impacts of climate change? Quantifying nesting habitat microclimate and use by little penguins (Eudyptula minor)

Climate change continues to have significant effects on seabird species globally. Extensive work has linked variability in marine climate with changes in phenology, reproductive success and distribution for a wide range of taxa. Despite the reliance of seabirds on island and coastal habitats for breeding, comparatively few studies address the compounding effects terrestrial climate change may have on reproductive success and survival, particularly for populations breeding at the warm edges of a species’ range. Edge populations may be key for not only predicting species’ responses to expected change in climate but also for maintaining long term adaptive capacity of a species. For edge populations, conservation may rely on the intensive management and restoration of terrestrial habitat to facilitate population resilience and buffer the adverse effects of climate change. Among the critical elements of successful conservation planning for long term species persistence is a comprehensive understanding of habitat use, microhabitat conditions and climate change impacts at range edges. This thesis investigated the use and microclimate conditions of nesting habitat used by a disjunct rear edge population of little penguins (Eudyptula minor), seeking to identify implications of terrestrial climate change for this species. To achieve this, I characterised little penguin nesting habitat on Penguin Island, Western Australia and quantified relationships between nest attributes, microclimate (temperature and humidity), nest use and reproductive success. I monitored 50 natural nests and 113 existing nest boxes fortnightly for nesting activity and reproductive success over three little penguin breeding cycles (2013 - 2016). Nest characteristic data were collected, and microclimate measurements recorded using temperature and humidity loggers. Subsequently, I implemented a manipulative study testing artificial nest design and shading treatments to determine how to most effectively emulate the microclimate of natural cavities. Little penguins did not select nest sites randomly, but instead based nest site selection on topographical, vegetation and nest site attributes. Natural nests were preferentially selected at sites with taller vegetation, close to a known landfall site and with a south-westerly facing entrance. In contrast, nest box use was predominately driven by the structure of the box, with longer boxes more likely to be used. Neither landscape nor nest site attributes were found to influence the overall success of either natural or artificial nests. Nest boxes were ineffective at replicating microclimate conditions of natural nests. Nest boxes experienced consistently higher daily maximum temperature (~2 ˚C) and maintained temperatures above little penguins’ upper thermoneutral limits (30 ˚C and 35 ˚C) for around one hour longer than natural nests. After accounting for ambient temperature, relative humidity and wind, fine scale biotic and abiotic nest characteristics also influenced the maximum daily nest temperature and hours of exposure to upper thermoneutral limits (reducing time of exposure by up to two hours in natural nests and three hours in nest boxes). To further investigate the potential impact of climate change on temperatures within nests, I fitted models which simulated a 2 ˚C temperature increase scenario. The number of days annually where natural and artificial nest conditions exceeded thermally stressful conditions (≥30 ˚C) are predicted to increase by approximately 37% and 56% and the number of days exceeding hyperthermic conditions (≥ 35 ˚C) are predicted to increase by approximately 41% and 49% respectively. Such changes will expose penguins to dangerous and potentially fatal thermal conditions, particularly during the late breeding and moulting phases of their annual cycle. Experimental manipulation of boxes and shading revealed nest design and shading methods were effective at reducing nest temperature. Shaded timber boxes and buried plastic tunnels had thermal profiles either comparable to, or up to 2 ˚C cooler than, natural nests. Compared to exposed boxes, artificial shading and shading vegetation had the greatest buffering effect, significantly lowering maximum nest temperature by around 4.5 ˚C and reducing the time of exposure to upper thermoneutral limits by approximately one hour. Results here provide critical insight into how predicted changes in terrestrial climate may compound marine climate change impacts on seabird colonies at latitudinal margins, providing a more complete understanding of the climate limitations and management implications of edge populations. This thesis revealed that current and future thermal environments of little penguin terrestrial habitat on Penguin Island can exceed physiological limits for this species. Intervention to improve artificial nests and better quantify consequences is urgently needed given recent estimates of a declining population could lead to the local extinction of this colony. I outline the potential to use well-designed artificial nests as a method for increasing the resilience of vulnerable populations. Crucially, this thesis reveals that management to ameliorate climate change impacts must be purposive and thoughtful and highlights the potential for poorly designed or positioned artificial nests to become not only ineffective but present an ecological trap, potentially accelerating population decline