Biotic Taxa Research Articles

Homogeneous selection and stochasticity overrule heterogeneous selection across biotic taxa and ecosystems

Deterministic factors including homogeneous and heterogeneous selection and stochastic factors jointly shape ecological communities. However, a quantitative synthesis of the factors underlying the balance among different assembly processes is lacking. Here, we synthesized data from 149 datasets covering major biotic groups and ecosystem types globally. We used a null model approach based on Raup–Crick dissimilarities and Bayesian meta‐regression to analyze the data. We found that communities were more under homogeneous selection than heterogeneous selection across biotic taxa and ecosystems. Environment selected species homogeneously more often at small scales while heterogeneously more often at large scales. Stochasticity also showed scale‐dependence as stochastic community assembly increased with study scale. Homogeneous and heterogeneous selection were strongest at high latitudes while stochastic factors were strongest in tropics. Marine systems had the highest degree of homogeneous selection and the lowest stochasticity. We provide the first analysis of community assembly across taxa and ecosystems which should be important for a better understanding of how communities respond to environmental change.

Of paleo-genes and Perch: what if an "alien" is actually a native?

Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an ecosystem or target it for removal. In some cases, however, such background information is inadequate or unavailable. Here we use paleo-DNA to re-evaluate the historical status of yellow perch in the 6 million acre Adirondack State Park of northern New York. Yellow perch DNA in a 2200-year sediment record reveals a long-term native status for these supposedly alien fish and challenges assumptions that they necessarily exclude native trout from upland lakes. Similar approaches could be applied to other species with uncertain historical distributions and could help to identify unrecognized pockets of biodiversity.

Климатическая зависимость биоты на территории Ямало-Ненецкого АО (количественный аспект)

Исследованы количественные закономерности распределения биотических таксонов на территории ЯНАО. Показана их связь с климатом через посредство индекса тепла (сумм положительных температур.) Найдены формулы географической (климатической) и иерархической зависимости количества таксонов растений и животных любого ранга. Введено понятие групповых (долевых) индексов тепла, относящихся к интервалам температур 0 – 5, 5 – 10 и 10 – t7 °C, определяющих существование и ареалы арктической, холодостойкой и теплолюбивой биоты. Показаны единство и взаимообусловленность существования растений и животных, их общая зависимость от климата.

Biotic interactions affecting potato production

Pest/pathogen interactions affecting potato production are reviewed. Many reported interactions in potatoes and other crops are best termed associations or interrelationships. True synergistics interactions can be expressed as Y = b1 x1 + b2 x2 + b3 (x1 x2) + - bn xn + e in which Y is a measure of plant growth, b1, b2, bn are constants, x1, x2, xn are independent variables and e is the error term. Examples of interactions including pathogen vectors, and various interactions involving different viruses and biotic taxa and among biotic taxa (e.g., virus-virus, virus-fungus, fungusbacteria, and nematode-fungus) in potatoes are cited. It is included that important interactions do occur in potato production systems and that additional research is needed to identify unknown interacting factors and to elucidate mechanisms of those previously described. Particular needs exist for holistic or synoptic studies to identify the role of interacting factors in total crop management.