scholarly journals The geographic mosaic of coevolution in mutualistic networks

2018 ◽  
Vol 115 (47) ◽  
pp. 12017-12022 ◽  
Author(s):  
Lucas P. Medeiros ◽  
Guilherme Garcia ◽  
John N. Thompson ◽  
Paulo R. Guimarães
Keyword(s):  
Gene Flow ◽  
Species Interactions ◽  
Analytical Approximation ◽  
Spatial Processes ◽  
Geographic Mosaic ◽  
Generalist Species ◽  
Interacting Species ◽  
Adaptive Landscapes ◽  
Surprising Effect ◽  
Mutualistic Networks

Ecological interactions shape adaptations through coevolution not only between pairs of species but also through entire multispecies assemblages. Local coevolution can then be further altered through spatial processes that have been formally partitioned in the geographic mosaic theory of coevolution. A major current challenge is to understand the spatial patterns of coadaptation that emerge across ecosystems through the interplay between gene flow and selection in networks of interacting species. Here, we combine a coevolutionary model, network theory, and empirical information on species interactions to investigate how gene flow and geographical variation in selection affect trait patterns in mutualistic networks. We show that gene flow has the surprising effect of favoring trait matching, especially among generalist species in species-rich networks typical of pollination and seed dispersal interactions. Using an analytical approximation of our model, we demonstrate that gene flow promotes trait matching by making the adaptive landscapes of different species more similar to each other. We use this result to show that the progressive loss of gene flow associated with habitat fragmentation may undermine coadaptation in mutualisms. Our results therefore provide predictions of how spatial processes shape the evolution of species-rich interactions and how the widespread fragmentation of natural landscapes may modify the coevolutionary process.

Species interactions and contemporary evolution

2019 ◽  
pp. 148-166
Author(s):  
Timothy G. Barraclough
Keyword(s):  
Gene Flow ◽  
Environmental Change ◽  
Species Interactions ◽  
Evolutionary Dynamics ◽  
Contemporary Evolution ◽  
Interacting Species ◽  
As Species ◽  
Species Shift ◽  
Tree Holes ◽  
Strength Of Competition

All organisms live within a diverse assemblage of many other species. Even with strict boundaries to gene flow, species interact in ways that shape their evolutionary dynamics. This chapter outlines how species interactions affect evolution of constituent species within a community. Models of competitive communities illustrate how interactions can constrain evolution, as species shift to occupy new regions with conditions similar to those they were previously adapted to. In contrast, coevolutionary interactions can stimulate evolution and amplify responses to environmental change. Experimental evolution on bacteria isolated from tree-holes formed by the roots of beech trees shows how species adapt to the presence of other species, leading to a decline in the strength of competition. Much more work is needed to investigate these effects in model assemblages of interacting species.

The Geographic Mosaic of Coevolution. By J. N. Thompson, pp. 443. University of Chicago Press, USA, 2005. ISBN 0 226 79762 7. £20 (US$28)

Parasitology ◽  
2005 ◽  
Vol 131 (5) ◽  
pp. 726-726
Author(s):  
ROBERT POULIN
Keyword(s):  
Gene Flow ◽  
Natural Selection ◽  
Conceptual Framework ◽  
Parasite Species ◽  
Prey Species ◽  
Geographic Mosaic ◽  
Local Networks ◽  
Interacting Species ◽  
Evolutionary Changes ◽  
University Of Chicago Press

It could be argued that much of evolution is really coevolution. Organisms do not exist in an ecological vacuum, but as parts of a network of interacting species. A given species may compete with others for access to prey species used as food, while itself serving as food to predator and parasite species. Natural selection will drive reciprocal evolutionary changes between interacting species. Across its geographical range, a species will encounter different local networks, since the same set of species do not co-occur everywhere. Thus, coevolutionary outcomes will vary in space, forming a geographical mosaic shaped by local adaptation and gene flow. This is the theme of John Thompson's new book, in which the author develops a conceptual framework for the study of coevolution.

scholarly journals Core-periphery structure in mutualistic networks: an epitaph for nestedness?

2020 ◽  
Author(s):  
Ana M. Martín González ◽  
Diego P. Vázquez ◽  
Rodrigo Ramos-Jiliberto ◽  
Sang Hoon Lee ◽  
Vincent Miele
Keyword(s):  
Species Interactions ◽  
Network Science ◽  
R Package ◽  
Ecological Networks ◽  
Interaction Matrix ◽  
Theoretical Studies ◽  
Topological Feature ◽  
Generalist Species ◽  
Mutualistic Networks ◽  
Specialist Species

ABSTRACTThe calculation of nestedness has become a routine analysis in the study of ecological networks, as it is commonly associated with community resilience, robustness and species persistence. While meaningful in species distributional patterns, for an interaction matrix to be nested, specialist species must interact with ordered subsets of subsequently more generalized species — not just with a lower number of species. However, after reviewing 419 papers on mutualistic networks published since nestedness was introduced for the study of species interactions in 2003, we have found that only two theoretical studies considered explicitly ordered subsets. Instead, most studies interpret nestedness as a core of densely connected generalist species, surrounded by a periphery of specialist species attached to this core — a so-called core-periphery structure. Such a topological feature is generally perceived as a core-periphery structure in network science. Here, we argue that the concept of core-periphery may be more relevant for studies on mutualistic networks than the concept of nestedness, as ecologists are usually not interested in exploring in detail the ordered subsets that characterize nestedness but instead use nestedness to describe a topology with a core of densely linked generalist species surrounded by a sparsely linked periphery of specialists. To illustrate our arguments and the quantification of core-periphery structures, we calculate core-periphery and nestedness in a large publicly available dataset of mutualistic networks. We also describe the calculation of core-periphery structures, its relationship with nestedness, and provide the code inside the R package econetwork for its calculation in mutualistic networks. We hope that our review will help ecologists to move beyond nestedness towards a more explicit representation of the structure of ecological networks.

scholarly journals Emergent speciation by multiple Dobzhansky-Muller incompatibilities

2014 ◽  
Author(s):  
Tiago Paixão ◽  
Kevin E. Bassler ◽  
Ricardo B. R. Azevedo
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Network Model ◽  
Neutral Network ◽  
Collective Effects ◽  
Neutral Networks ◽  
Adaptive Landscapes ◽  
Complex Interactions ◽  
Or Gene

The Dobzhansky-Muller model posits that incompatibilities between alleles at different loci cause speciation. However, it is known that if the alleles involved in a Dobzhansky-Muller incompatibility (DMI) between two loci are neutral, the resulting reproductive isolation cannot be maintained in the presence of either mutation or gene flow. Here we show that speciation can emerge through the collective effects of multiple neutral DMIs that cannot, individually, cause speciation-a mechanism we call emergent speciation. We investigate emergent speciation using models of haploid holey adaptive landscapes-neutral networks-with recombination. We find that certain combinations of multiple neutral DMIs can lead to speciation. Furthermore, emergent speciation is a robust mechanism that can occur in the presence of migration, and of deviations from the assumptions of the neutral network model. Strong recombination and complex interactions between the DMI loci facilitate emergent speciation. These conditions are likely to occur in nature. We conclude that the interaction between DMIs may cause speciation.

scholarly journals Evolutionary responses to conditionality in species interactions across environmental gradients

2015 ◽  
Author(s):  
Anna M. O’Brien ◽  
Ruairidh J.H. Sawers ◽  
Jeffrey Ross-Ibarra ◽  
Sharon Y. Strauss
Keyword(s):  
Statistical Models ◽  
Species Interactions ◽  
Environmental Gradients ◽  
Niche Partitioning ◽  
Character Displacement ◽  
Arms Race ◽  
Positive Interactions ◽  
Common Pattern ◽  
Interacting Species ◽  
Stressful Environments

AbstractThe outcomes of many species interactions are conditional on the environments in which they occur. A common pattern is that outcomes grade from being more positive under stressful conditions to more antagonistic or neutral under benign conditions. The evolutionary implications of conditionality in interactions have received much less attention than the documentation of conditionality itself, with a few notable exceptions. Here, we predict patterns of adaptation and co-adaptation between partners along abiotic gradients, positing that when interactions become more positive in stressful environments, fitness outcomes for mutations affecting interactions align across partners and selection should favor greater mutualistic adap-tation and co-adaptation between interacting species. As a corollary, in benign environments, if interactions are strongly antagonistic, we predict antagonistic co-adaptation resulting in Red Queen or arms-race dynamics, or reduction of antagonism through character displacement and niche partitioning. We predict no adaptation if interactions are more neutral. We call this the CoCoA hypothesis: (Co)-adaptation and Conditionality across Abiotic gradients. We describe experimental designs and statistical models that allow testing predictions of CoCoA, with a focus on positive interactions. While only one study has included all the elements to test CoCoA, we briefly review the literature and summarize study findings relevant to CoCoA and highlight opportunities to test CoCoA further.

scholarly journals A dynamic occupancy model for interacting species with two spatial scales

2020 ◽  
Author(s):  
Eivind Flittie Kleiven ◽  
Frederic Barraquand ◽  
Olivier Gimenez ◽  
John-André Henden ◽  
Rolf Anker Ims ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Species Interactions ◽  
Spatial Scales ◽  
Species Interaction ◽  
Camera Traps ◽  
Occupancy Models ◽  
Occupancy Model ◽  
Interacting Species ◽  
Multi Scale ◽  
Extinction Probabilities

1AbstractOccupancy models have been developed independently to account for multiple spatial scales and species interactions in a dynamic setting. However, as interacting species (e.g., predators and prey) often operate at different spatial scales, including nested spatial structure might be especially relevant in models of interacting species. Here we bridge these two model frameworks by developing a multi-scale two-species occupancy model. The model is dynamic, i.e. it estimates initial occupancy, colonization and extinction probabilities - including probabilities conditional to the other species’ presence. With a simulation study, we demonstrate that the model is able to estimate parameters without bias under low, medium and high average occupancy probabilities, as well as low, medium and high detection probabilities. We further show the model’s ability to deal with sparse field data by applying it to a multi-scale camera trapping dataset on a mustelid-rodent predator-prey system. The field study illustrates that the model allows estimation of species interaction effects on colonization and extinction probabilities at two spatial scales. This creates opportunities to explicitly account for the spatial structure found in many spatially nested study designs, and to study interacting species that have contrasted movement ranges with camera traps.

scholarly journals Cascading speciation among mutualists and antagonists in a tree–beetle–fungi interaction

2018 ◽  
Vol 285 (1881) ◽  
pp. 20180694 ◽  
Author(s):  
R. R. Bracewell ◽  
D. Vanderpool ◽  
J. M. Good ◽  
D. L. Six
Keyword(s):  
Pinus Ponderosa ◽  
Species Interactions ◽  
Trophic Levels ◽  
Host Tree ◽  
Dendroctonus Brevicomis ◽  
Published Data ◽  
Primary Host ◽  
Reduced Representation ◽  
Interacting Species ◽  
Show Evidence

Cascading speciation is predicted to occur when multiple interacting species diverge in parallel as a result of divergence in one species promoting adaptive differentiation in other species. However, there are few examples where ecological interactions among taxa have been shown to result in speciation that cascades across multiple trophic levels. Here, we test for cascading speciation occurring among the western pine beetle ( Dendroctonus brevicomis ), its primary host tree ( Pinus ponderosa ), and the beetle's fungal mutualists ( Ceratocystiopsis brevicomi and Entomocorticium sp. B). We assembled genomes for the beetle and a fungal symbiont and then generated reduced representation genomic data (RADseq) from range-wide samples of these three interacting species. Combined with published data for the host tree, we present clear evidence that the tree, the beetle, and the fungal symbionts are all genetically structured into at least two distinct groups that have strongly codiverged with geographical isolation. We then combine our genomic results with diverse population and laboratory-based data to show evidence for reproductive isolation at each level of the cascade and for coevolution of both antagonistic and mutualistic species interactions within this complex network.

scholarly journals Temperature/Body Size Interactions and Species Interaction in Montane Ponds in Grand Teton National Park

1991 ◽  
Vol 15 ◽  
pp. 180-181
Author(s):  
Bruce Woodward ◽  
Sandra Mitchell
Keyword(s):  
Body Size ◽  
Species Interactions ◽  
National Park ◽  
Size Variation ◽  
Species Interaction ◽  
First Year ◽  
Grand Teton National Park ◽  
Interacting Species ◽  
Temperature Regimes ◽  
Body Sizes

We visited Grand Teton National Park in May, June and July 1991 to begin research on species interactions in shallow montane ponds. Our primary interests were in how body size variation influences species interactions, and how temperature influences body size and thus species interactions. Our goal in the first year was to explore the extant variation in temperature regimes and body sizes of potentially interacting species, and examine some of these species interactions.

scholarly journals Relative contribution of ecological and biological attributes in the fine-grain structure of ant-plant networks

2015 ◽  
Author(s):  
Cecilia Díaz-Castelazo ◽  
Victor Rico-Gray
Keyword(s):  
Habitat Heterogeneity ◽  
Abiotic Factors ◽  
Grain Structure ◽  
Ecological Communities ◽  
Plant Interactions ◽  
Generalist Species ◽  
Facultative Mutualism ◽  
Interacting Species ◽  
Biotic Defense ◽  
Fine Grain

Background. Ecological communities of interacting species analyzed as complex networks, revealed that species dependence on their counterpart is more complex than expected at random. For ant-plant networks (mediated by extrafloral nectar), links among species are asymmetric (nested), forming a core of generalist species. Proposed factors affecting network organization include encounter probability (species abundances, habitat heterogeneity), behavior, phylogeny and body size. While the importance of underlying factors that influence structure of ant-plant networks have been separately explored, simultaneous contribution of several biological and ecological attributes inherent to the species, guild or habitat level have not been addressed. Methods. For a tropical seasonal site we recorded frequency of pairwise ant-plant interactions mediated by extrafloral nectaries, attributes of interacting species, habitat attributes, cover of plants with EFNs, and studied the resultant network structure. We addressed for the first time the role of mechanistic versus neutral determinants at the “fine-grain” structure (pairwise interactions) of ant-plant networks, studying the simultaneous contribution of several plant, ant, and habitat attributes in prevailing interactions as well as in overall network topology (community). Results. Our studied network was highly-nested, non-modular, with core species in general having high species strengths (higher strength values for ants than plants) and low specialization; plants had higher dependences on their counterparts. The significant factor explaining network and fine-grain structure was habitat heterogeneity in vegetation structure (open vs. shaded habitats), with no evidence of neutral (abundance) effects. Discussion. Core ant species are relevant to most plants species at the network, the latter depending more on the former, core ants showing adaptations to nectar consumption and deterrent behavior, suggestive of potential biotic defense at a community scale. At our study site spatiotemporal heterogeneity is so strong, that emerges at community-level structural properties, depicting influence of abiotic factors in facultative mutualism. Frequent occurrence of morphologically-diverse EFNs at all habitats suggests plasticity in plant strategies for biotic defense provided by ants.

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