scholarly journals Predicting abundances of plants and pollinators using a simple compartmental mutualistic model

2015 ◽  
Vol 282 (1808) ◽  
pp. 20150592 ◽  
Author(s):  
Hugo Fort ◽  
Muhittin Mungan

Key gaps to be filled in population and community ecology are predicting the strength of species interactions and linking pattern with process to understand species coexistence and their relative abundances. In the case of mutualistic webs, like plant–pollinator networks, advances in understanding species abundances are currently limited, mainly owing to the lack of methodological tools to deal with the intrinsic complexity of mutualisms. Here, we propose an aggregation method leading to a simple compartmental mutualistic population model that captures both qualitatively and quantitatively the size-segregated populations observed in a Mediterranean community of nectar-producing plant species and nectar-searching animal species. We analyse the issue of optimal aggregation level and its connection with the trade-off between realism and overparametrization. We show that aggregation of both plants and pollinators into five size classes or compartments leads to a robust model with only two tunable parameters. Moreover, if, in each compartment, (i) the interaction coefficients fulfil the condition of weak mutualism and (ii) the mutualism is facultative for at least one party of the compartment, then the interactions between different compartments are sufficient to guarantee global stability of the equilibrium population.

2021 ◽  
Vol 17 (10) ◽  
pp. e1008899
Author(s):  
Susanne Pettersson ◽  
Martin Nilsson Jacobi

Understanding ecosystem stability and functioning is a long-standing goal in theoretical ecology, with one of the main tools being dynamical modelling of species abundances. With the help of spatially unresolved (well-mixed) population models and equilibrium dynamics, limits to stability and regions of various ecosystem robustness have been extensively mapped in terms of diversity (number of species), types of interactions, interaction strengths, varying interaction networks (for example plant-pollinator, food-web) and varying structures of these networks. Although many insights have been gained, the impact of spatial extension is not included in this body of knowledge. Recent studies of spatially explicit modelling on the other hand have shown that stability limits can be crossed and diversity increased for systems with spatial heterogeneity in species interactions and/or chaotic dynamics. Here we show that such crossing and diversity increase can appear under less strict conditions. We find that the mere possibility of varying species abundances at different spatial locations make possible the preservation or increase in diversity across previous boundaries thought to mark catastrophic transitions. In addition, we introduce and make explicit a multitude of different dynamics a spatially extended complex system can use to stabilise. This expanded stabilising repertoire of dynamics is largest at intermediate levels of dispersal. Thus we find that spatially extended systems with intermediate dispersal are more robust, in general have higher diversity and can stabilise beyond previous stability boundaries, in contrast to well-mixed systems.


2021 ◽  
Vol 13 (5) ◽  
pp. 2468
Author(s):  
Nguyen Hong Hai ◽  
Yousef Erfanifard ◽  
Van Bac Bui ◽  
Trinh Hien Mai ◽  
Any Mary Petritan ◽  
...  

Studying spatial patterns and habitat association of plant communities may provide understanding of the ecological mechanisms and processes that maintain species coexistence. To conduct assessments of correlation between community compositions and habitat association, we used data from two topographically different plots with 2 ha area in tropical evergreen forests with the variables recorded via grid systems of 10 × 10 m subplots in Northern-Central Vietnam. First, we tested the relationship between community composition and species diversity indices considering the topographical variables. We then assessed the interspecific interactions of 20 dominant plant species using the nearest-neighbor distribution function, Dij(r), and Ripley’s K-function, Kij(r). Based on the significant spatial association of species pairs, indices of interspecific interaction were calculated by the quantitative amounts of the summary statistics. The results showed that (i) community compositions were significantly influenced by the topographic variables and (ii) almost 50% significant pairs of species interactions were increased with increasing spatial scales up to 10–15 m, then declined and disappeared at scales of 30–40 m. Segregation and partial overlap were the dominant association types and disappeared at larger spatial scales. Spatial segregation, mixing, and partial overlap revealed the important species interactions in maintaining species coexistence under habitat heterogeneity in diverse forest communities.


2007 ◽  
Vol 56 (1-6) ◽  
pp. 101-110 ◽  
Author(s):  
Chr. Wehenkel ◽  
F. Bergmann ◽  
H.-R. Gregorius

Abstract Studies on plant communities of various annual species suggest that there are particular biotic interactions among individuals from different species which could be the basis for long-term species coexistence. In the course of a large survey on species-genetic diversity relationships in several forest tree communities, it was found that statistically significant differences exist among isozyme genotype frequencies of conspecific tree groups, which differ only by species identity of their neighbours. Based on a specific measure, the association of the neighbouring species with the genotypes of the target species or that of the genotypes with the neighbouring species was quantified. Since only AAT and HEK of the five analysed enzyme systems differed in their genotype frequencies among several tree groups of the same target species, a potential involvement of their enzymatic function in the observed differences was discussed. The results of this study demonstrate a fine-scale genetic differentiation within single tree species of forest communities, which may be the result of biotic interactions between the genetic structure of a species and the species composition of its community. This observation also suggests the importance of intraspecific genetic variation for interspecific adaptation.


2018 ◽  
Vol 2 ◽  
pp. e25343
Author(s):  
José Augusto Salim ◽  
Antonio Saraiva ◽  
Kayna Agostini ◽  
Marina Wolowski ◽  
Allan Veiga ◽  
...  

The Brazilian Plant-Pollinator Interactions Network*1 (REBIPP) aims to develop scientific and teaching activities in plant-pollinator interaction. The main goals of the network are to: generate a diagnosis of plant-pollinator interactions in Brazil; integrate knowledge in pollination of natural, agricultural, urban and restored areas; identify knowledge gaps; support public policy guidelines aimed at the conservation of biodiversity and ecosystem services for pollination and food production; and encourage collaborative studies among REBIPP participants. To achieve these goals the group has resumed and built on previous works in data standard definition done under the auspices of the IABIN-PTN (Etienne Américo et al. 2007) and FAO (Saraiva et al. 2010) projects (Saraiva et al. 2017). The ultimate goal is to standardize the ways data on plant-pollinator interactions are digitized, to facilitate data sharing and aggregation. A database will be built with standardized data from Brazilian researchers members of the network to be used by the national community, and to allow sharing data with data aggregators. To achieve those goals three task groups of specialists with similar interests and background (e.g botanists, zoologists, pollination biologists) have been created. Each group is working on the definition of the terms to describe plants, pollinators and their interactions. The glossary created explains their meaning, trying to map the suggested terms into Darwin Core (DwC) terms, and following the TDWG Standards Documentation Standard*2 in definition. Reaching a consensus on terms and their meaning among members of each group is challenging, since researchers have different views and concerns about which data are important to be included into a standard. That reflects the variety of research questions that underlie different projects and the data they collect. Thus, we ended up having a long list of terms, many of them useful only in very specialized research protocols and experiments, sometimes rarely collected or measured. Nevertheless we opted to maintain a very comprehensive set of terms, so that a large number of researchers feel that the standard meets their needs and that the databases based on it are a suitable place to store their data, thus encouraging the adoption of the data standard. An update of the work will soon be available at REBIPP website and will be open for comments and contributions. This proposal of a data standard is also being discussed within the TDWG Biological Interaction Data Interest Group*3 in order to propose an international standard for species interaction data. The importance of interaction data for guiding conservation practices and ecosystem services provision management has led to the proposal of defining Essential Biodiversity Variables (EBVs) related to biological interactions. Essential Biodiversity Variables (Pereira et al. 2013) were developed to identify key measurements that are required to monitoring biodiversity change. EBVs act as intermediate abstract layer between primary observations (raw data) and indicators (Niemeijer 2002). Five EBV classes have been defined in an initial stage: genetic composition, species populations, species traits, community composition, ecosystem function and ecosystem structure. Each EBV class defines a list of candidate EBVs for biodiversity change monitoring (Fig. 1). Consequently, digitalization of such data and making them available online are essential. Differences in sampling protocols may affect data scalability across space and time, hence imposing barriers to the full use of primary data and EBVs calculation (Henry et al. 2008). Thus, common protocols and methods should be adopted as the most straightforward approach to promote integration of collected data and to allow calculation of EBVs (Jürgens et al. 2011). Recently a Workshop was held by GLOBIS B*4 (GLOBal Infrastructures for Supporting Biodiversity research) to discuss Species Interactions EBVs (February, 26-28, Bari, Italy). Plant-pollinator interactions deserved a lot of attention and REBIPP's work was presented there. As an outcome we expect to define specific EBVs for interactions, and use plant-pollinators as an example, considering pairwise interactions as well as interaction network related variables. The terms in the plant-pollinator data standard under discussion at REBIPP will provide information not only on EBV related with interactions, but also on other four EBV classes: species populations, species traits, community composition, ecosystem function and ecosystem structure. As we said, some EBVs for specific ecosystem functions (e.g. pollination) lay beyond interactions network structures. The EBV 'Species interactions' (EBV class 'Community composition') should incorporate other aspects such as frequency (Vázquez et al. 2005), duration and empirical estimates of interaction strengths (Berlow et al. 2004). Overall, we think the proposed plant-pollinator interaction data standard which is currently being developed by REBIPP will contribute to data aggregation, filling many data gaps and can also provide indicators for long-term monitoring, being an essential source of data for EBVs.


2021 ◽  
Vol 8 ◽  
Author(s):  
Veronica Hsu ◽  
Holly V. Moeller

Metabolic symbiosis is a form of symbiosis in which organisms exchange metabolites, typically for mutual benefit. For example, acquired phototrophs like Paramecium bursaria obtain photosynthate from endosymbiotic green algae called Chlorella. In addition to facilitating the persistence of P. bursaria by providing a carbon source that supplements P. bursaria’s heterotrophic digestion of bacteria, symbiotic Chlorella may impact competitive interactions between P. bursaria and other bacterivores, with cascading effects on community composition and overall diversity. Here, we tested the effects of metabolic symbiosis on coexistence by assessing the impacts of acquired phototrophy on priority effects, or the effect of species arrival order on species interactions, between P. bursaria and its competitor Colpidium. Our results suggest light-dependent priority effects. The acquired phototroph benefited from metabolic symbiosis during sequential arrival of each organism in competition, and led to increased growth of late-arriving Colpidium. These findings demonstrate that understanding the consequences of priority effects for species coexistence requires consideration of metabolic symbiosis.


2020 ◽  
Vol 287 (1918) ◽  
pp. 20192211 ◽  
Author(s):  
Annika Schirmer ◽  
Julia Hoffmann ◽  
Jana A. Eccard ◽  
Melanie Dammhahn

Intraspecific trait variation is an important determinant of fundamental ecological interactions. Many of these interactions are mediated by behaviour. Therefore, interindividual differences in behaviour should contribute to individual niche specialization. Comparable with variation in morphological traits, behavioural differentiation between individuals should limit similarity among competitors and thus act as a mechanism maintaining within-species variation in ecological niches and facilitating species coexistence. Here, we aimed to test whether interindividual differences in boldness covary with spatial interactions within and between two ecologically similar, co-occurring rodent species ( Myodes glareolus , Apodemus agrarius ). In five subpopulations in northeast Germany, we quantified individual differences in boldness via repeated standardized tests and spatial interaction patterns via capture–mark–recapture ( n = 126) and automated VHF telemetry ( n = 36). We found that boldness varied with space use in both species. Individuals of the same population occupied different spatial niches, which resulted in non-random patterns of within- and between-species spatial interactions. Behavioural types mainly differed in the relative importance of intra- versus interspecific competition. Within-species variation along this competition gradient could contribute to maintaining individual niche specialization. Moreover, behavioural differentiation between individuals limits similarity among competitors, which might facilitate the coexistence of functionally equivalent species and, thus, affect community dynamics and local biodiversity.


2017 ◽  
Vol 115 (3) ◽  
pp. 543-548 ◽  
Author(s):  
Allison M. Louthan ◽  
Robert M. Pringle ◽  
Jacob R. Goheen ◽  
Todd M. Palmer ◽  
William F. Morris ◽  
...  

Predicting how species’ abundances and ranges will shift in response to climate change requires a mechanistic understanding of how multiple factors interact to limit population growth. Both abiotic stress and species interactions can limit populations and potentially set range boundaries, but we have a poor understanding of when and where each is most critical. A commonly cited hypothesis, first proposed by Darwin, posits that abiotic factors (e.g., temperature, precipitation) are stronger determinants of range boundaries in apparently abiotically stressful areas (“stress” indicates abiotic factors that reduce population growth), including desert, polar, or high-elevation environments, whereas species interactions (e.g., herbivory, competition) play a stronger role in apparently less stressful environments. We tested a core tenet of this hypothesis—that population growth rate is more strongly affected by species interactions in less stressful areas—using experimental manipulations of species interactions affecting a common herbaceous plant, Hibiscus meyeri (Malvaceae), across an aridity gradient in a semiarid African savanna. Population growth was more strongly affected by four distinct species interactions (competition with herbaceous and shrubby neighbors, herbivory, and pollination) in less stressful mesic areas than in more stressful arid sites. However, contrary to common assumptions, this effect did not arise because of greater density or diversity of interacting species in less stressful areas, but rather because aridity reduced sensitivity of population growth to these interactions. Our work supports classic predictions about the relative strength of factors regulating population growth across stress gradients, but suggests that this pattern results from a previously unappreciated mechanism that may apply to many species worldwide.


2020 ◽  
Author(s):  
Paul J. CaraDonna ◽  
Nickolas M. Waser

AbstractEcological communities consist of species that are joined in complex networks of interspecific interaction. The interactions that networks depict often form and dissolve rapidly, but this temporal variation is not well integrated into our understanding of the causes and consequences of network structure. If interspecific interactions exhibit temporal flexibility across time periods over which organisms co-occur, then the emergent structure of the corresponding network may also be temporally flexible, something that a temporally-static perspective would miss. Here, we use an empirical system to examine short-term flexibility in network structure (connectance, nestedness, and specialization), and in individual species interactions that contribute to that structure. We investigated weekly plant-pollinator networks in a subalpine ecosystem across three summer growing seasons. To link the interactions of individual species to properties of their networks, we examined weekly temporal variation in species’ contributions to network structure. As a test of the potential robustness of networks to perturbation, we also simulated the random loss of species from weekly networks. We then compared the properties of weekly networks to the properties of cumulative networks that aggregate field observations over each full season. A week-to-week view reveals considerable flexibility in the interactions of individual species and their contributions to network structure. For example, species that would be considered relatively generalized across their entire activity period may be much more specialized at certain times, and at no point as generalized as the cumulative network may suggest. Furthermore, a week-to-week view reveals corresponding temporal flexibility in network structure and potential robustness throughout each summer growing season. We conclude that short-term flexibility in species interactions leads to short-term variation in network properties, and that a season-long, cumulative perspective may miss important aspects of the way in which species interact, with implications for understanding their ecology, evolution, and conservation.


2019 ◽  
Author(s):  
Benno I. Simmons ◽  
Hannah S. Wauchope ◽  
Tatsuya Amano ◽  
Lynn V. Dicks ◽  
William J. Sutherland ◽  
...  

AbstractSpecies are central to ecology and conservation. However, it is the interactions between species that generate the functions on which ecosystems and humans depend. Despite the importance of interactions, we lack an understanding of the risk that their loss poses to ecological communities. Here, we quantify risk as a function of the vulnerability (likelihood of loss) and importance (contribution to network stability in terms of species coexistence) of 4330 mutualistic interactions from 41 empirical pollination and seed dispersal networks across six continents. Remarkably, we find that more vulnerable interactions are also more important: the interactions that contribute most to network stability are those that are most likely to be lost. Furthermore, most interactions tend to have more similar vulnerability and importance across networks than expected by chance, suggesting that vulnerability and importance may be intrinsic properties of interactions, rather than only a function of ecological context. These results provide a starting point for prioritising interactions for conservation in species interaction networks and, in areas lacking network data, could allow interaction properties to be inferred from taxonomy alone.


2021 ◽  
Vol 118 (12) ◽  
pp. e2023872118
Author(s):  
Ignasi Bartomeus ◽  
Serguei Saavedra ◽  
Rudolf P. Rohr ◽  
Oscar Godoy

Ecological theory predicts that species interactions embedded in multitrophic networks shape the opportunities for species to persist. However, the lack of experimental support of this prediction has limited our understanding of how species interactions occurring within and across trophic levels simultaneously regulate the maintenance of biodiversity. Here, we integrate a mathematical approach and detailed experiments in plant–pollinator communities to demonstrate the need to jointly account for species interactions within and across trophic levels when estimating the ability of species to persist. Within the plant trophic level, we show that the persistence probability of plant species increases when introducing the effects of plant–pollinator interactions. Across trophic levels, we show that the persistence probabilities of both plants and pollinators exhibit idiosyncratic changes when experimentally manipulating the multitrophic structure. Importantly, these idiosyncratic effects are not recovered by traditional simulations. Our work provides tractable experimental and theoretical platforms upon which it is possible to investigate the multitrophic factors affecting species persistence in ecological communities.


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