Species Coexistence

Resource partitioning has been recognized as a major driver affecting fish communities, with the potential to reduce interespecific competition. This is the result of differences in feeding apparatuses and feeding mode, location of the fish species in the water column and swimming ability, as well as type and size of prey and its availability. The present study surveys a highly limited aquatic system in semi-arid Brazil with regard to habitat and food availability, with very low diversity of fish, and poor in underwater habitat structures and prey, with the objective of understanding resource partitioning among fish species under such conditions. Three species of Cichlidae (Pisces: Perciformes) were sampled during the dry and wet seasons and had their stomach contents analyzed to evaluate food consumption. The resource partition among fish species was evaluated based on Pianka’s niche overlap index and tested for significance against null models. It was observed a low overlap among the study species in food resource use, with individuals tending to specialize to select some food items. This is likely the result of low natural variation in abundance of specific food items associated with fish preferences (both morphological and behavioral). These results support evidence that, in Brazilian semi-arid aquatic systems, coexistence of fish species seems to be enhanced by the partition of food items at specific trophic levels. Within this context, flow variability would have a key hole in fish coexistence by promoting a high diversity of aquatic habitat elements available for colonization of fish and their prey. Furthermore, food resources available to fish play an important role in this dynamics since prey foods are expected to vary in abundance as the habitat changes.

Mutualisms-cooperative interactions among different species-are known to influence global biodiversity. Nevertheless, theoretical and empirical work has led to divergent hypotheses about how mutualisms modulate diversity. We ask here when and how mutualisms influence species richness. Our synthesis suggests that mutualisms can promote or restrict species richness depending on mutualist function, the level of partner dependence, and the specificity of the partnership. These characteristics, which themselves are influenced by environmental and geographic variables, regulate species richness at different scales by modulating speciation, extinction, and community coexistence. Understanding the relative impact of these mechanisms on species richness will require the integration of new phylogenetic comparative models as well as the manipulation and monitoring of experimental communities and their resulting interaction networks. Mutualisms and Species Richness: An Ecological and Evolutionary Conundrum Mutualisms-cooperative interactions among different species-are ubiquitous, have shaped much of global biodiversity, and have allowed organisms to access or outsource crucial functions such as transport, nutrition, cleaning, and defense. A large body of research has suggested strong links between mutualisms and the generation and maintenance of species diversity on Earth. However, this suite of hypotheses is complex, spans multiple scales, and can at times be contradictory. For example, at the ecological scale, May [1] argued that mutualisms have no effects on species diversity within communities. He argued that, because negative density-dependence (see Glossary) favors the coexistence of multiple species, mutualisms-which are associated with positive density-dependence-should do the opposite. This was later contrasted by newer empirical and theoretical studies highlighting asymmetry in the effects of mutualisms and suggesting that the formation of mutualistic networks plays a key role in promoting coexistence among multiple species [2-4]. The debate continues, with some researchers suggesting that species interactions including mutualisms play little role in shaping evolution [5], and that partnerships tend to stabilize species rather than promoting their diversification [6]. By contrast, a growing body of work claims the opposite, namely that mutualistic partnerships are an integral driver of morphological and evolutionary diversification [7-9]. In this review we ask when and how mutualisms influence diversity. Instead of including other metrics of diversity, we specifically focus on species richness to simplify our approach. Because this topic is so broad, we focus on two major areas of research. In the first we address how mutualisms impact lineage diversification rates, and in the second we examine how mutualisms impact on community coexistence, focusing on the modulation of competition dynamics. Highlights There are contrasting hypotheses about the influence of mutualisms on species richness. We provide a synthetic framework for how mutualisms influence species richness at the ecological and evolutionary scales. Mutualisms can promote or restrict species richness depending on their function, level of dependence, and specificity. Because the outcomes of mutualisms are highly dependent on environmental variables, we forecast that the effects of mutualisms on species richness are also strongly influenced by biotic, abiotic, and geographic variables across ecological and evolutionary timescales. Although our review depicts the complex and multifaceted impact of mutu-alisms on species richness, it also highlights a key gap: our understanding of the relative importance of the mechanisms through which mutual-isms affect biodiversity. We suggest new methodological approaches to fill this gap.

Claves para mejorar la convivencia en contextos socioeducativos. Las instituciones socioeducativas, pueden ser espacios de vida y trabajo, donde la mejora de la convivencia y la paz se perciban con transparencia. esto se puede lograr a través de un proyecto común materializado en unas claves debidamente planificadas para vivirlas en la comunidad educativa: la educación en valores, la colaboración, la comunicación, el clima institucional, la toma de decisiones, la participación, la educación emocional, de la paciencia y de la interioridad.
Socio-educational institutions might become spaces of life and work, where the improvement of coexistence and peace are perceived with transparency. this can be achieved through a common project that crystallises in a set of keys properly planned, to be lived within the educational community: education in values, collaboration, communication, institutional atmosphere, decision making , participation, emotional education, patience and interiority.

Understanding forest stand structural change is crucial for forest ecosystem research and management. The aim of our research was to identify structural and compositional changes and possible natural and anthropogenic causes of these changes in an old‐growth silver fir‐beech forest in the Dinaric mountains of Slovenia. Data on stand structure of the Rajhenavski Rog (51.14 ha) forest reserve originated from traditional methods, including five successive full callipering (1957–2007), two regeneration inventories and analysis of developmental phases (1984, 2007). A drastic decrease in the silver fir proportion in the last 50 years was probably caused by two indirect anthropogenic factors: polluted air and heavy browsing damage of silver fir regeneration. Nevertheless, other factors including reciprocal replacement of fir and beech and climate change also influenced the species composition, as similar processes were documented in the past with less air pollution. Furthermore, the alternation of fir and beech often developed asynchronously, regardless of ungulate density. Although the vertical profile of the old‐growth forest was opened due to the loss of fir trees during past decades, the establishment of more light‐demanding species was uncommon, primarily because the growing stock and forest climate were sustained. The results suggest a high stability of mixed Dinaric old‐growth forest ecosystems.