Disentangling local, metapopulation, and cross-community sources of stabilization and asynchrony in metacommunities Matthew Hammond, Michel Loreau, Claire de Mazancourt, Jurek Kolasa To cite this version: Matthew Hammond, Michel Loreau, Claire de Mazancourt, Jurek Kolasa. Disentangling local, metapopulation, and cross-community sources of stabilization and asynchrony in metacommunities. Ecosphere, Ecological Society of America, 2020, 11 (4), pp.e03078. 10.1002/ecs2.3078. hal-02565047 HAL Id: hal-02565047 https://hal.archives-ouvertes.fr/hal-02565047 Submitted on 6 May 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. SYNTHESIS & INTEGRATION Disentangling local, metapopulation, and cross-community sources of stabilization and asynchrony in metacommunities 1, 2 2 1 MATTHEW HAMMOND , MICHEL LOREAU, CLAIRE DE MAZANCOURT, AND JUREK KOLASA 1Department of Biology, McMaster University, 1280 Main Street West, Hamilton Ontario L8S 4K1 Canada 2Centre for Biodiversity Theory and Modelling, Theoretical and Experimental Ecology Station, CNRS, 2 Route du CNRS, 09200 Moulis, France Citation: Hammond, M., M. Loreau, C. de Mazancourt, and J. Kolasa. 2020. Disentangling local, metapopulation, and cross- community sources of stabilization and asynchrony in metacommunities. Ecosphere 11(4):e03078. 10.1002/ecs2.3078 Abstract. Asynchronous fluctuations of populations are essential for maintaining stable levels of bio- mass and ecosystem function in landscapes. Yet, understanding the stabilization of metacommunities by asynchrony is complicated by the existence of multiple forms of asynchrony that are typically studied inde- pendently: Community ecologists, for instance, focus on asynchrony within and among local communities, while population ecologists emphasize asynchrony of populations in metapopulations. Still, other forms of asynchrony, such as that which underlies the spatial insurance effect, are not captured by any existing ana- lytical frameworks. We therefore developed a framework that would in one analysis unmask the stabiliz- ing roles of local communities and metapopulations and so unify these perspectives. Our framework shows that metacommunity stabilization arises from one local and two regional forms of asynchrony: (1) asynchrony among species of a local community, (2) asynchrony among populations of a metapopulation, and (3) cross-community asynchrony, which is between different species in different local communities and underlies spatial insurance. For each type of stabilization, we derived links to diversity indices and associated diversity–stability relationships. We deployed this framework in a set of rock pool invertebrate metacommunities in Discovery Bay, Jamaica, to partition sources of stabilization and test their dependence on diversity. Cross-community asynchrony was the dominant form of stabilization, accounting for >60% of total metacommunity stabilization despite being undetectable with existing frameworks. Environmental variation influenced types of stabilization through different mechanisms. pH and dissolved oxygen, for example, increased asynchrony by decorrelating local species, while salinity did so by changing the abun- dance structure of metapopulations. Lastly, all types of asynchrony depended strongly on different types of diversity (alpha, metapopulation, and beta diversity drove local, metapopulation, and cross-community asynchrony, respectively) to produce multiple diversity–stability relationships within metacommunities. Our new partition of metacommunity dynamics highlights how different elements—from local communi- ties to metapopulations—combine to stabilize metacommunities and depend critically on contrasting envi- ronmental regimes and diversities. Understanding and balancing these sources of stability in dynamic landscapes is a looming challenge for the future. We suggest that synthetic frameworks which merge eco- logical perspectives will be essential for grasping and safeguarding the stability of natural systems. Key words: asynchrony; community; diversity; diversity–stability; metacommunity; metapopulation; partitioning; stability; variability. Received 27 August 2019; revised 3 December 2019; accepted 18 December 2019; final version received 6 February 2020. Corresponding Editor: Cory Merow. Copyright: © 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. E-mail: [email protected] ❖ www.esajournals.org 1 April 2020 ❖ Volume 11(4) ❖ Article e03078 SYNTHESIS & INTEGRATION HAMMOND ET AL. INTRODUCTION prevent a deeper understanding of stabilization at the metacommunity scale. Community-level biomass or abundance var- The analytical barrier is that the main local ies over time and governs the rise and fall of community framework used to date (Wang and ecosystem functions in landscapes. Such system- Loreau 2014) does not capture some forms of level fluctuations are stabilized when compo- regional asynchrony that interest ecologists. Asyn- nents (e.g., species) fluctuate asynchronously so chrony among populations of a metapopulation, that declines in one component are compensated for example, helps to stabilize overall metacom- by increases in another (Doak et al. 1998, Yachi munity biomass (Wilcox et al. 2017) and is critical and Loreau 1999, Schindler et al. 2015). Because for species persistence in landscapes (Anderson asynchrony reduces variation of community or et al. 2015, Schindler et al. 2015). But this form of ecosystem properties, it is important for ensuring asynchrony is only implicit in the local commu- their reliability. Alaskan salmon returns, for nity framework (Wilcox et al. 2017), leaving its example, are stabilized by the existence of hun- contribution to stability at the metacommunity dreds of uncoupled populations (Schindler et al. scale unquantified. Another form of asynchrony 2010). Tallgrass prairie biomass is similarly stabi- overlooked by current frameworks is that which lized where fire and grazing create a mosaic of underlies the spatial insurance hypothesis (Yachi asynchronous patches (McGranahan et al. 2016). and Loreau 1999), wherein different species occu- In turn, biomass stabilization can be crucial for pying different patches fluctuate asynchronously stabilizing ecosystem functions like net primary and disperse to maintain ecosystem function production (Wilcox et al. 2017). (Gonzalez et al. 2009). Recent work has isolated the mechanisms by The above gaps may be seen to result from a which asynchrony stabilizes natural systems. conceptual problem: The form of asynchrony Support for the insurance hypothesis (Yachi and measured depends on the organizational hierar- Loreau 1999) highlights the stabilizing effect of chy used to conceptualize and study a metacom- asynchronous species responses to environmen- munity (Fig. 1). Viewed as a set of local tal fluctuations (Leary and Petchey 2009, Hector communities (Fig. 1A), for instance, the meta- et al. 2010, Loreau 2010). Confirmed portfolio community is stabilized by asynchrony among effects (sensu Doak et al. 1998, Tilman 1999), local communities (which we call type I asyn- meanwhile, demonstrate the power of diversity chrony) and asynchrony of species within those to stabilize communities or functional groups local communities (type II; Wang and Loreau when species dynamics are weakly correlated 2014). But if viewed (equally validly) as a set of (Bai et al. 2004, Cardinale et al. 2012). But while metapopulations (Fig. 1B), it is stabilized by stabilization by asynchrony is well understood in asynchrony among species metapopulations local communities (Thibaut and Connolly 2013), (type III) and asynchrony of populations within there is an urgent conservation need to scale that those metapopulations (type IV). understanding up to metacommunities (Wang Progress in stability research depends on and Loreau 2014). bringing these overlapping metacommunity per- In a recent advance, Wang and Loreau (2014) spectives together in a single frame of reference. partitioned the variability of total metacommunity Wang et al. (2019) made an important step in this — c biomass or abundance gamma variability ( CV) direction by relating the local community and —into local and regional components represent- metapopulation hierarchies in an analytical a ing the variability of local communities ( CV)and framework. However, the approach does not rec- asynchrony among those communities (b). Their oncile local communities and metapopulations in approach has rapidly become the most common a single analysis to give their independent contri- in metacommunity asynchrony research and has butions to metacommunity stability. Nor does it underscored the importance of spatial heterogene- capture the fifth form of asynchrony (type V)— ity in stabilizing metacommunity biomass and among different species in different local com- ecosystem function (McGranahan et al. 2016, Wil- munities—that is the generative mechanism