Giovanni Strona

European Commission | ec

A well-known problem in numerical ecology is how to recombine presence-absence matrices without altering row and column totals. A few solutions have been proposed, but all of them present some issues in terms of statistical robustness (that is, their capability to generate different matrix configurations with the same probability) and their perform...

Complex ecological networks appear robust to primary extinctions, possibly due to consumers' tendency to specialize on dependable (available and persistent) resources. However, modifications to the conditions under which the network has evolved might alter resource dependability. Here, we ask whether adaptation to historical conditions can increase...

Significance Although oil palm cultivation represents an important source of income for many tropical countries, its future expansion is a primary threat to tropical forests and biodiversity. In this context, and especially in regions where industrial palm oil production is still emerging, identifying “areas of compromise,” that is, areas with high...

Ecosystems face both local hazards, such as over-exploitation, and global hazards, such as climate change. Since the impact of local hazards attenuates with distance from humans, local extinction risk should decrease with remoteness, making faraway areas safe havens for biodiversity. However, isolation and reduced anthropogenic disturbance may incr...

Although theory identifies co-extinctions as a main driver of biodiversity loss, their role at the planetary scale has yet to be estimated. We subjected a global model of interconnected terrestrial vertebrate food webs to future (2020–2100) climate and land-use changes. We predict a 17.6% (± 0.16% SE) average reduction of local vertebrate diversity...

This report describes the maps on tree species distribution routinely produced at Joint Research Centre, and the data sets used to produce them. Its aim is to help those searching for information on forest tree species distribution in Europe and to identify which of the maps might fit their needs, what their strengths and weaknesses are, and what d...

Species interactions play a fundamental role in ecosystems. They affect where species can live, how their population sizes fluctuate through time, and how environmental perturbations cascade through communities. But few ecological communities have complete data describing such interactions, which is an obstacle to understanding how ecosystems funct...

Climate change is a pervasive threat to biodiversity. While range shifts are a known consequence of climate warming contributing to regional community change, less is known about how species’ positions shift within their climatic niches. Furthermore, whether the relative importance of different climatic variables prompting such shifts varies with c...

The world is collapsing at breakneck speed. The detrimental effects of human presence and activities are so widespread that finding “naturalness” is becoming more challenging every day. This calls for the fundamental question of whether we can halt or, at least, slow down this process. From a pessimistic yet realistic perspective, we have to recogn...

The structure of interactions between species within a community plays a key role in maintaining biodiversity. Previous studies have found that the effects of these structures might substantially differ depending on interaction type, for example, a highly connected and nested architecture stabilizes mutualistic communities, while the stability of a...

Coral restoration initiatives are gaining significant momentum in a global effort to enhance the recovery of degraded coral reefs. However, the implementation and upkeep of coral nurseries are particularly demanding, so that unforeseen breaks in maintenance operations might jeopardize well established projects. In the last two years, the COVID‐19 p...

We present “EU-Trees4F”, a dataset of current and future potential distributions of 67 tree species in Europe at 10 km spatial resolution. We provide both climatically suitable future areas of occupancy and the future distribution expected under a scenario of natural dispersal for two emission scenarios (RCP 4.5 and RCP 8.5) and three time steps (2...

Network theory offers innovative tools to explore the complex ecological mechanisms regulating species associations and interactions. Although interest in ecological networks has grown steadily during the last two decades, the application of network approaches has been unequally distributed across different study systems: while some kinds of intera...

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. Bottom-up cascades occur when changes in the primary producers in a network elicit flow-on effects to higher trophic levels. However, it remains unclear what determines a species’ vulnerability to bottom-up cascades, and whether such cascades were a lar...

This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Abstract 1. Smallholder farmers are some of the poorest and most food insecure people on Earth. Their high nutritional and economic reliance on h...

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. Bottom–up cascades occur when changes in the primary producers in a network elicit flow-on effects to higher trophic levels. However, it remains unclear what determines a species' vulnerability to bottom–up cascades and whether such cascades were a larg...

Each species on Earth is linked to all other species by an elusive net of ecological interactions. This means that any extinction might affect to some degree of other species. Yet, conservation tends to focus on species—especially charismatic ones-instead of ecological processes. This attitude is problematic, as it might lead to disregarding critic...

Due to the many challenges associated with collecting comprehensive information defining the nature and intensity of pairwise relationships between interacting species, often we have to rely on networks that provide a highly simplified picture of reality. Limitations arise, for example, from using undirected or unweighted links to represent scenari...

Species dispersal ability has played a lead role in millions of years of evolutionary, biogeographical and ecological processes, eventually leading to modern communities. However, the increasing global mobility is now boosting the frequency of events where species are translocated to localities far beyond their natural dispersal range. For the larg...

A simple way to model co-extinctions in resource–consumer networks (such as host-parasite networks or food webs) is: (i) removing nodes according to a particular criterion (either random or informed); and then, (ii) identifying which other nodes in the network are left without interacting partners (and, hence, doomed to co-extinction). Although int...

The previous chapters have focused on the direct effects of resource loss on consumers. From that perspective, co-extinction events occur (either locally or globally) whenever a consumer runs out of resources, such as in the case of a plant left with no pollinators, a parasite left with no hosts, or a predator left with no prey. However, such direc...

Intuitively a consumer who relies on a limited set of resources for survival would be more at risk of going co-extinct than a generalist capable of using multiple resources. This simple idea contrasts with the fact that specialization is widespread in the natural world (e.g. most parasite species can use just one or a few hosts). The paradox can be...

Differently from previous mass extinct events identifying the main culprits of the ongoing diversity loss is relatively straightforward. We kill animals, we destroy habitats, we pollute the environment, we promote biological invasions. And, of course, we fuel global warming. These mechanisms are not the only ones behind the ongoing Sixth Mass Extin...

The rapid technological development is generating unprecedented opportunities for scientific research. In particular, the development of artificial intelligence (AI) techniques, with computers becoming increasingly independent in performing tasks and—to a certain degree—taking decisions, is opening new frontiers. Machine learning techniques are now...

Networks offer a convenient model to represent countless real-world situations. The use of networks as a framework to explore ecological complexity has become increasingly popular in the last couple of decades. The study of food webs, which has a long history in ecology, has been complemented by a partially distinct and entirely novel research fiel...

This book provides, for the first time, a comprehensive overview of the fundamental roles that ecological interactions play in extinction processes, bringing to light an underground of hidden pathways leading to the same dark place: biodiversity loss. We are in the midst of the sixth mass extinction. We see species declining and vanishing one after...

The ecological concept of “nestedness” has been initially formulated in the context of biogeography and conservation biology, referring, in particular, to non-random distribution patterns of species within a set of localities. There, nestedness quantifies the tendency for the species composition of a community to be a subset of any other species-ri...

Many organisms have complex life cycles characterized by multiple, substantially different stages of development. Often, different stages depend on different resources and are characterized by a different degree of specificity. There are various potential selective advantages associated with a complex life cycle. For example, in the case of trophic...

The direct pressures exerted by global change and human activity on global biodiversity—alteration of local environmental conditions, habitat destruction, mass and selective killing of individuals—account for only one part of the current biodiversity crisis. Increasing theoretical and empirical evidence supports the idea that secondary (co-) extinc...

Simulating progressive, multiple species extinctions in ecological networks while keeping track of the network’s response to subsequent species loss can be an informative exercise. However, the nature of the information emerging from such exercise strongly depends on the identity of nodes (species) removed from the network and the order in which we...

An integrated approach using morphological and genetic data is needed to disentangle taxonomic uncertainties affecting the hydrozoan families Sphaerocorynidae and Zancleopsidae. Here we used this approach to accurately characterise species in these families, identify the previously unknown polyp stages of the genera Euphysilla and Zancleopsis, whic...

Significance Species loss can weaken the trophic interactions that underpin ecosystem functioning. Coral reefs are the world’s most diverse marine ecosystem, harboring interaction networks of extraordinary complexity. We show that, despite this complexity, global coral reef food webs are governed by a suite of highly consistent energetic pathways,...

Reef fishes are a treasured part of marine biodiversity, and also provide needed protein for many millions of people. Although most reef fishes might survive projected increases in ocean temperatures, corals are less tolerant. A few fish species strictly depend on corals for food and shelter, suggesting that coral extinctions could lead to some sec...

Marginal areas of rice production have the potential to meet increasing oil palm demand in India, without sacrificing forests and associated biodiversity.

The causes of Sahul’s megafauna extinctions remain uncertain, although several interacting factors were likely responsible. To examine the relative support for hypotheses regarding plausible ecological mechanisms underlying these extinctions, we constructed the first stochastic, age-structured models for 13 extinct megafauna species from five funct...

The species–area relationship (SAR) describes a range of related phenomena that are fundamental to the study of biogeography, macroecology and community ecology. While the subject of ongoing debate for a century, surprisingly, no previous book has focused specifically on the SAR. This volume addresses this shortfall by providing a synthesis of the...

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. However, it remains unclear whether trophic cascades were a large contributor to the megafauna extinctions that swept across several continents in the Late Pleistocene. The pathways to megafauna extinctions are particularly unclear for Sahul (landmass c...

Wildfires represent an important factor in the disturbance in Mediterranean ecosystems, although the effects of wildfires on the insect communities of mountain environments remain largely unknown. This research investigated the effect of fire on dung beetles in a Mediterranean high-altitude area, located in Central Italy (1500m elevation). Sampling...

Understanding species’ roles in food webs requires an accurate assessment of their trophic niche. However, it is challenging to delineate potential trophic interactions across an ecosystem, and a paucity of empirical information often leads to inconsistent definitions of trophic guilds based on expert opinion, especially when applied to hyperdivers...

The causes of Sahul’s megafauna extinctions remain uncertain, although multiple, interacting factors were likely responsible. To test hypotheses regarding plausible ecological mechanisms underlying these extinctions, we constructed the first stochastic, age-structured models for 13 extinct megafauna species from five functional/taxonomic groups, as...

Found throughout the tree of life and in every ecosystem, parasites are some of the most diverse, ecologically important animals on Earth—but in almost all cases, the least protected by wildlife or ecosystem conservation efforts. For decades, ecologists have been calling for research to understand parasites' important ecological role, and increasin...

Ecosystems are under unprecedented and accelerating pressures. Much work on understanding resilience to these pressures has, so far, focussed on the ecosystem. However, understanding a system’s behaviour also requires knowledge of its component parts and their interactions. Here we present a framework for understanding ‘biological resilience’, or t...

Accurate delimitation of species and their relationships is a fundamental issue in evolutionary biology and taxonomy and provides essential implications for conservation management. Scleractinian corals are difficult to identify because of their ecophenotypic and geographic variation and their morphological plasticity. Furthermore, phylogenies base...

The diversity of life on our planet has produced a remarkable variety of biological traits that characterize different species. Such traits are widely employed instead of taxonomy to increase our understanding of biodiversity and ecosystem functioning. However, for species’ trophic niches, one of the most critical aspects of organismal ecology, a p...

The concept of generic diversity expresses the ‘diversification’ of species into genera in a community. Since niche overlap is assumed to be higher in congeneric species, competition should increase generic diversity. On the other hand, generic diversity might be lower in highly selective environments, where only species with similar adaptations ca...

Outbreaks of a plant disease in a landscape can be meaningfully modelled using networks with nodes representing individual crop-fields, and edges representing potential infection pathways between them. Their spatial structure, which resembles that of a regular lattice, makes such networks fairly robust against epidemics. Yet, it is well-known how t...

We introduce a suite of software tools aimed at investigating multiple bio-ecological facets of aquatic Groundwater Dependent Ecosystems (GDEs). The suite focuses on: (1) threats posed by pollutants to GDE invertebrates (Ecological Risk, ER); (2) threats posed by hydrological and hydromorphological alterations on the subsurface zone of lotic system...

Aims Quantifying β‐diversity (differences in the composition of communities) is central to many ecological studies. There are many β‐diversity metrics, falling mostly into two approaches: variance‐based (e.g., the Sørensen index), or diversity partitioning (e.g., additive β‐diversity). The former cannot be used when species–sites matrices are unava...

Recent studies have highlighted the importance of higher‐order competitive interactions in stabilizing population dynamics in multi‐species communities. But how does the structure of competitive hierarchies affect population dynamics and extinction processes? We tackled this important question by using spatially explicit simulations of ecological d...

Climate change and human activity are dooming species at an unprecedented rate via a plethora of direct and indirect, often synergic, mechanisms. Among these, primary extinctions driven by environmental change could be just the tip of an enormous extinction iceberg. As our understanding of the importance of ecological interactions in shaping ecosys...

Europe’s major X. fastidiosa outbreaks have progressed steadily in the past years as data on the bacterial strains causing them, and on the host range and vectors of the pathogen in various regions, became available. The initial uncertainty around these critical epidemiological aspects of the X. fastidiosa invasions hampered estimates of their rate...

The Curveball algorithm is an efficient and unbiased procedure for randomizing bipartite networks (or their matrix counterpart) while preserving node degrees. Here we introduce two extensions of the procedure, making it capable to randomize also unimode directed and undirected networks. We provide formal mathematical proofs that the two extensions,...

A network analysis has been developed exploiting WiFi localization technique. The paper demonstrates how the use of Wi-Fi localization techniques to build high-resolution contact networks is highly relevant for various aspects of global security; for example, in the case of public event people flow monitoring can be analyzed and how a specific even...

Contact networks are convenient models to investigate epidemics, with nodes and links representing potential hosts and infection pathways, respectively. The outcomes of outbreak simulations on networks are driven both by the underlying epidemic model, and by the networks' structural properties, so that the same pathogen can generate different epide...

Outbreaks of the corallivorous crown-of-thorns seastars have received increasing attention due to their negative impacts on coral reefs in the Indo-Pacific Ocean. However, outbreaks in remote and dislocated islands are still poorly understood. This study aims to begin filling informational gaps regarding outbreaks of Acanthaster planci in the remot...

Several recent studies have tackled the issue of optimal network immunization by providing efficient criteria to identify key nodes to be removed in order to break apart a network, thus preventing the occurrence of extensive epidemic outbreaks. Yet, although the efficiency of those criteria has been demonstrated also in empirical networks, preventi...

In spite of growing evidence that climate change may dramatically affect networks of interacting species, whether-and to what extent-ecological interactions can mediate species' responses to disturbances is an open question. Here we show how a largely overseen association such as that between hydrozoans and scleractinian corals could be possibly as...

Comparing the structure of presence/absence (i.e. binary) matrices with those of randomized counterparts is a common practice in ecology. However, differences in the randomization procedures (null models) can affect the results of the comparisons, leading matrix structural patterns to appear either ‘random’ or not. Subjectivity in the choice of one...

Investigating the structure of ecological networks can help unravel the mechanisms promoting and maintaining biodiversity. Recently, Strona and Veech (10.1111/2041-210X.12395) introduced a new metric (, pronounced 'nos'), that allows assessment of structural patterns in networks ranging from complete node segregation to perfect nestedness, and that...

Highlights • Nematomorphs induce their arthropod host to jump into water. • The drowning host is often eaten by aquatic predators. • This creates an opportunity for nematomorphs to increase life-cycle complexity. • I speculate on why nematomorphs have always dropped this opportunity.

Several studies have identified the tendency for species to share interacting partners as a key property to the functioning and stability of ecological networks. However, assessing this pattern has proved challenging in several regards, such as finding proper metrics to assess node overlap (sharing), and using robust null modeling to disentangle si...

Binary presence-absence matrices (rows = species, columns = sites) are often used to quantify patterns of species co-occurrence, and to infer possible biotic interactions from these patterns. Previous classifications of co-occurrence patterns as nested, segregated, or modular have led to contradictory results and conclusions. These analyses usually...

Binary presence-absence matrices (rows = species, columns = sites) are often used to quantify patterns of species co-occurrence, and to infer possible biotic interactions from these patterns. Previous classifications of co-occurrence patterns as nested, segregated, or modular have led to contradictory results and conclusions. These analyses usually...

The insect vector borne bacterium Xylella fastidiosa was first detected in olive trees in Southern Italy in 2013, and identified as the main culprit behind the ‘olive quick decline syndrome’. Since then, the disease has spread rapidly through Italy’s main olive oil producing region. The epidemiology of the outbreak is largely unstudied, with the li...