Structural equation modeling of a winnowed soil microbiome identifies how invasive plants re-structure microbial networks      
Mamet et al., 2019

The development of microbial networks is central to ecosystem functioning and is the hallmark of complex natural systems. Characterizing network development over time and across environmental gradients is hindered by the millions of potential interactions among community members, limiting interpretations of network evolution. We developed a feature selection approach using data winnowing that identifies the most ecologically influential microorganisms within a network undergoing change. Using a combination of graph theory, leave-one-out analysis, and statistical inference, complex microbial communities are winnowed to identify the core organisms responding to external gradients or functionality, and then network development is evaluated against these externalities. In a plant invasion case study, the winnowed microbial network became more influential as the plant invasion progressed as a result of direct plant-microbe links rather than the expected indirect plant–soil–microbe links. This represents the first use of structural equation modeling to predict microbial network evolution, which requires identification of keystone taxa and quantification of the ecological processes underpinning community structure and function patterns.

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https://go.nature.com/2TPOasb

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Graham Harman: Morton’s Hyperobjects and the Anthropocene

Pseudosalix handleyi
a 48 million year old fossils plant relative of willows 
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Basic Principles of Temporal Dynamics      

Ryo et al., 2019

Temporal dynamics are inherently complex.

Concepts and techniques have flourished to understand ecological temporal dynamics in recent years.

A key finding of recent studies is that driver–response relationships are not necessarily constant through time, but rather, that they are conditioned by the recent and historical past.

Basic principles of temporal dynamics need to be summarized to increase the understanding and predictability of complex temporal dynamics in ecology and evolution.

All ecological disciplines consider temporal dynamics, although relevant concepts have been developed almost independently. We here introduce basic principles of temporal dynamics in ecology. We figured out essential features that describe temporal dynamics by finding similarities among about 60 ecological concepts and theories. We found that considering the hierarchically nested structure of complexity in temporal patterns (i.e. hierarchical complexity) can well describe the fundamental nature of temporal dynamics by expressing which patterns are observed at each scale. Across all ecological levels, driver–response relationships can be temporally variant and dependent on both short- and long-term past conditions. The framework can help with designing experiments, improving predictive power of statistics, and enhancing communications among ecological disciplines.

Hierarchical Complexity. The idea deals with driver–response relationships in time-series across three levels of complexity. The levels are hierarchically nested, as single-event (i.e., one driver and one response) is a subset of multiple events that are a part of the trajectory. The key property is that driver–response relationships are not necessarily constant through time, but they can change over time due to recent and historical past experience. Hierarchical complexity can be observed at any scale. Temporal dynamics at each of the levels affect each other.

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https://bit.ly/2GzDaMb

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Album Benary (1876-1882)
Ernst Benary

Meta‐ecosystem processes alter ecosystem function and can promote herbivore‐mediated coexistence 
Justin N. Marleau Frederic Guichard, 2019

Herbivory and dispersal play roles in the coexistence of primary producers with shared resource limitation by imposing trade‐offs either through apparent competition or dispersal limitation. These mechanisms of coexistence can further interact with meta‐ecosystem effects, which results in spatial heterogeneity through the movement of herbivores and nutrients. Here, we investigate how herbivores influence autotroph coexistence through a meta‐ecosystem effect, and how this effect couples mechanisms of coexistence to ecosystem structure and functioning. We articulate this framework through a parameterized one resource‐k producer‐one herbivore meta‐ecosystem model. The results show that herbivore movement with nutrient recycling can generate spatial heterogeneity to allow coexistence where the well‐mixed system predicts competitive exclusion. Furthermore, the presence of movement alters local and regional ecosystem functioning even when coexistence would occur without movement. These results highlight how meta‐ecosystem theory can provide a mechanistic context for the observed complexity of biodiversity‐ecosystem function relationships.

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https://bit.ly/2VY79CL

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James Collier
https://bit.ly/2UYEOe4
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Structure, spatial dynamics, and stability of novel seed dispersal mutualistic networks in Hawaiʻi      

Vizentin-Bugoni et al., 2019

When humans introduce exotic species to sensitive ecosystems, invasion and extinction of native species often follow. The resulting ecological communities can develop unusual interactions between the survivors and newcomers. Vizentin-Bugoni et al. analyzed the structure of seed dispersal networks in Hawai'i, where native bird species have been mostly replaced by invaders. They found that the native plants now depend on the invasive birds for seed dispersal. The network of dispersal interactions is complex and stable, which are features of native seed-dispersal networks in other parts of the world. It appears that introduced species may, in some circumstances, become integrated into native ecosystems

Abstract

Increasing rates of human-caused species invasions and extinctions may reshape communities and modify the structure, dynamics, and stability of species interactions. To investigate how such changes affect communities, we performed multiscale analyses of seed dispersal networks on Oʻahu, Hawaiʻi. Networks consisted exclusively of novel interactions, were largely dominated by introduced species, and exhibited specialized and modular structure at local and regional scales, despite high interaction dissimilarity across communities. Furthermore, the structure and stability of the novel networks were similar to native-dominated communities worldwide. Our findings suggest that shared evolutionary history is not a necessary process for the emergence of complex network structure, and interaction patterns may be highly conserved, regardless of species identity and environment. Introduced species can quickly become well integrated into novel networks, making restoration of native ecosystems more challenging than previously thought.

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https://science.sciencemag.org/content/364/6435/78

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Hungarian Racka Sheep 

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FOREST by Carol Ann Duffy