Las huellas de la defaunación en el Antropoceno : el colapso de los mutualismos de dispersión de semillas

Programa de Doctorado en Medio Ambiente y SociedadLínea de Investigación: Biodiversidad y Biología de la ConservaciónClave Programa: DAMCódigo Línea: 83Las características demográficas y genéticas de las poblaciones de plantas dependen en gran medida de los patrones de dispersión de semillas (y de polen). En muchas especies estos procesos se realizan a través de relaciones mutualistas con animales frugívoros, que reciben a cambio recursos tróficos. Los cambios producidos por el hombre en el medio natural han provocado la extinción de muchos de estos frugívoros, especialmente las especies de mayor tamaño. Cuando esto ocurre, es probable que los procesos ecológicos en los que intervienen, entre ellos la dispersión de semillas, también se vean afectados, provocando un efecto cascada dentro de las comunidades naturales. Sería esperable a largo plazo, por tanto, una reducción de la capacidad de reclutamiento y de la diversidad genética y un aumento de la estructura espacial en las poblaciones de plantas que dispersan. Además se esperaría que estos efectos fuesen más acusados en aquellos ecosistemas donde existe una baja redundancia funcional, como las islas oceánicas. El objetivo de esta tesis doctoral, es por tanto, evaluar cuales son las consecuencias demográficas y genéticas de la reducción del tamaño de los frugívoros para las plantas que dispersan en ambientes insulares. Nuestro modelo de estudio es Neochamaelea pulverulenta (Rutaceae) un arbusto endémico de Canarias. Esta planta se distribuye en tres islas, con un escenario ecológico muy contrastado en cada una ellas desde el punto de vista del tamaño de su único dispersor, los lagartos gigantes de las Islas Canarias (Gallotia spp.).Universidad Pablo de Olavide. Escuela de Doctorad

Downsized mutualisms: Consequences of seed dispersers' body-size reduction for early plant recruitment

© 2014 Geobotanisches Institut ETH, Stiftung Ruebel. Extinction-driven, body-size reduction of seed dispersers (i.e. an ecological downsizing resulting from severe defaunation) can entail the loss of unique ecological functions, and impair plant regeneration. However, the manner in which the downsizing of mutualistic animals affects seed dispersal and plant recruitment remains understudied. Here, we took advantage of a natural experiment in the Canarian archipelago to document the consequences of lizards body-size reduction (. Gallotia, Lacertidae) on the recruitment of Neochamaelea pulverulenta (Rutaceae), which relies exclusively on these frugivores for seed dispersal. Subsequent to the arrival of humans (ca. 2000-2500 yr BP), the extinction of large-bodied lizards generated a gradient of increasing defaunation on the three islands inhabited by this plant. We hypothesized a significant reduction, and eventually collapse, of early seedling recruitment mirroring the defaunation intensity of the frugivores. We sampled 42 populations spanning the whole geographic range of the plant to examine the quantitative (age structure pattern) and qualitative components (proportion of seedlings growing outside the canopy, number of seedlings established outside the canopy relative to the number of adults - effective recruitment rate, and seedling vigour) of plant regeneration. Our results show that the age structure patterns did not differ among the three contrasted insular scenarios. However, we found significant reductions in seedling recruitment outside the canopy, effective recruitment rate, and delayed negative effects on seedling vigour in populations hosting small- to medium-sized lizard species. Thus, extirpation of large seed-dispersers did not cause substantial reductions in quantitative components of seed dispersal, but determined declines in qualitative aspects impairing dispersal effectiveness. Our study highlights the importance of examining all components of the dispersal and recruitment process to properly document the regeneration outcomes of plants in defaunated, downsized ecological scenarios.Peer Reviewe

Preserving habitat quality at local and landscape scales increases wild bee diversity in intensive farming systems

Biological diversity is influenced by many environmental factors, which can act either at a local scale (e.g. quality and quantity of feeding and nesting resources, habitat type) or at a landscape scale (e.g. habitat fragmentation, composition and configuration of landscape features). To effectively manage or promote biodiversity in heterogeneous environments such as intensive agrosystems, a thorough knowledge of the spatial and temporal scale of ecological factor effects is required. This study investigates the effects of ecological correlates on local wild bee diversity in semi-natural farmland habitats, and predicts changes in species richness according to local-scale and landscape-scale correlates to further guide bee conservation practices. Local floral richness, the proportion of semi-natural habitats in the landscape (1000 m radius) and the type of semi-natural habitats influenced bee richness at a field scale. However, the magnitude of the effect varied seasonally and according to local bee abundance. Model predictions showed that increasing floral richness on farms had a greater effect on bee richness than increasing the proportion of semi-natural habitats. While increasing the number of semi-natural habitats would be a more effective strategy for promoting bee diversity at the landscape scale, it may not be feasible in intensive farming systems.info:eu-repo/semantics/acceptedVersio

Diversity, functionality, and resilience under increasing harvesting intensities in woodlands of northern Patagonia

Sustainable forest management relies on the understanding of biodiversity response to disturbance and the ecological resilience of the system. The dynamic equilibrium hypothesis (DEM) predicts that site productivity will modulate the effects of disturbance gradient on biodiversity. Also, considering functional diversity (eco-morfo-phisicological traits related to resource usage) is needed to understand the effect of species gains and losses on ecosystem functionality. Here we assess the response of understory plant taxonomic and functional diversity to increasing harvesting intensities (0, 30, 50 and 70% of basal area removed) at three woodland sites of contrasting biomass growth (productivity) in northern Patagonia. Also, we assessed resilience based on comparisons with undisturbed treatments four years after initial harvest. In agreement with DEM, both taxonomic and functional diversity peaked at high, medium, or low harvesting intensities in the high-, medium-, or low-productivity site, respectively. Taxonomic composition was clearly determined by site productivity (biomass growth), while no pattern emerged for functional composition. Functional traits related to light use showed different responses: specific leaf area was only affected by site productivity while leaf chlorophyll content was affected by an interaction between harvesting intensity and site productivity. Interestingly, there was no effect of harvesting intensity on the resilience of taxonomic diversity and functional composition. Only for functional diversity, harvesting intensity was as important as site productivity. In the high and intermediate productivity sites the traits that characterizes the system were more resilient and resembled the control treatment after four years of low or high (but not intermediate) harvesting intensities. Our results support the use of the DEM on forest interventions and the importance of considering both taxonomic and functional composition, as the consideration of functional traits related to resource use strategies have different implications when considering the resilience of the system.info:eu-repo/semantics/acceptedVersio

Fruit abundance and trait matching determine diet type and body condition across frugivorous bird populations

Research on seed‐dispersal mutualisms has been highly unbalanced towards the plants, largely overlooking the fitness effects of fruit resources on frugivorous animals. Moreover, despite morphological mismatches like gape limitation may reduce the abundance of fruits that are actually accessible to a frugivore species, there is very little evidence on the trait‐matching implications from a frugivore's perspective. Here, we refine recent resource‐provisioning models to comprehensively test the joint effects of fruit abundance and trait matching on diet type and body condition (a surrogate of fitness) across frugivorous bird populations: Sardinian warblers Curruca melanocephala inhabiting ten Mediterranean forests differing in the abundance and composition of fleshy fruits. We hypothesised the abundance of fruit resources to have positive effects on the degree of frugivory and body condition of warblers, and such effects to be more pronounced when accounting for both trait matching (accessible fruits) and resource provisioning (energy in accessible fruits). We found a sharp threshold over which warblers shifted from a diet with very little or even no fruits to a predominantly frugivorous diet with increasing the local abundance of accessible fruits. We also found a strong positive relationship between the abundance of accessible fruits and the body condition of warblers (body mass and residual body mass), an effect that was more pronounced in females than in males. Although diet type and body condition were much better predicted when accounting for trait matching, accounting for resource provisioning did not improve the explanatory power of fruit resources. The fact that we detected strong and sex‐dependent effects of fruit resources on body condition just a few weeks before the breeding season suggests that fruit resources likely affect the timing and success of reproduction, a question that deserves further research. Our findings provide new insight into the fitness consequences of seed‐dispersal mutualisms for frugivorous animals.info:eu-repo/semantics/acceptedVersio

Multi-isotopic assessments of spatio-temporal diet variability: the case of two sympatric gulls in the western Mediterranean

In predator populations, changes in foraging behaviour in response to spatio-temporal variability of prey are expected. Prey depletion might cause trophic niche widening in generalist species, but not in specialists, which are expected to increase their foraging effort without diet shifts. In sympatric species feeding on similar resources, reduced food availability can increase interspecific competition and cause trophic niche segregation. To understand these processes, we studied the spatio-temporal variability in diet and niche width in 2 sympatric gull species, the yellow-legged gull Larus michahellis and Audouin’s gull Ichthyaetus audouinii, which have experienced exponential growth in recent decades due to an increase in anthropogenic food subsidies. We sampled feathers from chicks of both species in several colonies along the western Mediterranean from 2009 to 2011 and performed stable isotope analysis of carbon, nitrogen and sulphur on these feathers. Bayesian modelling shows that both species displayed opportunistic behaviour if different types of resources were available, but could also narrow their trophic niche if 1 resource was abundant. We also provide evidence of trophic segregation between the 2 gull species, suggesting the occurrence of interspecific competition for food. Our meta-population approach provides a comprehensive view of the trophic ecology and the competitive interactions of these gull species. We emphasize the usefulness of 3-dimensional isotope analyses to correctly assess spatio-temporal variability in trophic behaviour of predator species, revealing differences that would remain hidden in single population studies or when using only the isotopic ratios of 2 elements.info:eu-repo/semantics/acceptedVersio

Policies for ecological intensification of crop production

Ecological intensification aims to increase crop productivity by enhancing biodiversity and associated ecosystem services, while minimizing the use of synthetic inputs and cropland expansion. Policies to promote ecological intensification have emerged in different countries, but they are still scarce and vary widely across regions. Here, we propose ten policy targets that governments can follow for ecological intensification

Plant Breeding and Management Strategies to Minimize the Impact of Water Scarcity and Biotic Stress in Cereal Crops under Mediterranean Conditions

Wheat and rice are two main staple food crops that may suffer from yield losses due to drought episodes that are increasingly impacted by climate change, in addition to new epidemic outbreaks. Sustainable intensification of production will rely on several strategies, such as efficient use of water and variety improvement. This review updates the latest findings regarding complementary approaches in agronomy, genetics, and phenomics to cope with climate change challenges. The agronomic approach focuses on a case study examining alternative rice water management practices, with their impact on greenhouse gas emissions and biodiversity for ecosystem services. The genetic approach reviews in depth the latest technologies to achieve fungal disease resistance, as well as the use of landraces to increase the genetic diversity of new varieties. The phenomics approach explores recent advances in high-throughput remote sensing technologies useful in detecting both biotic and abiotic stress effects on breeding programs. The complementary nature of all these technologies indicates that only interdisciplinary work will ensure significant steps towards a more sustainable agriculture under future climate change scenarios.info:eu-repo/semantics/publishedVersio

Agricultural policies against invasive species generate contrasting outcomes for climate change mitigation and biodiversity conservation

Direct consequences of biological invasions on biodiversity and the environment have been largely documented. Yet collateral indirect effects mediated by changes in agri-environmental policies aimed at combating invasions remain little explored. Here we assessed the effects of recent changes in water management in rice farming, which are aimed at buffering the impact of the invasive apple snail (Pomacea maculata, Lamarck) on greenhouse gas emissions and diversity of waterbird communities. We used observational data from a 2-year field monitoring (2015–2016) performed at the Ebro Delta regional scale. We found that drying rice fields reduced methane emission rates by 82% (2015) and 51% (2016), thereby reducing the contribution of rice farming to climate change. However, there was a marked reduction (75% in 2015 and 57% in 2016) in waterbird diversity in dry fields compared with flooded fields, thus suggesting that post-invasion policies might hinder biodiversity conservation. Our results highlight the need for accounting for potential collateral effects during the policy decision-making process to design efficient agricultural management plans that lessen undesirable agri-environmental outcomes.info:eu-repo/semantics/acceptedVersio

Value-Added Compounds with Health Benefits Produced from Cheese Whey Lactose

Cheese whey (CW) is the yellow-green liquid main by-product from cheese manufacturing. Historically, it has been recognized as a major environmental pollutant. Nowadays, it represents a source of high-quality nutrients, such as lactose. Enzymatic bioprocesses, chemical synthetic reactions and microbial bioprocesses use lactose as substrate to obtain relevant derivatives such as lactitol, lactulose, lactosucrose, sialyllactose, kefiran and galacto-oligosaccharides. These lactose derivatives stimulate the growth of indigenous bifidobacteria and lactobacilli improving the intestinal motility, enhancing immunity and promoting the synthesis of vitamins. Also, they have versatile applications in pharmaceutical, biotechnological and food industries. Therefore, this book chapter shows the state of the art focusing on recent uses of CW lactose to produce value-added functional compounds and discusses new insights associated with their human health-promoting effects and well-being