Ecological network
An ecological network is a representation of the
Properties
Historically, research into ecological networks developed from descriptions of trophic relationships in aquatic food webs; however, recent work has expanded to look at other food webs as well as webs of mutualists. Results of this work have identified several important properties of ecological networks.
Complexity (linkage density): the average number of links per species. Explaining the observed high levels of complexity in ecosystems[1] has been one of the main challenges and motivations for ecological network analysis, since early theory predicted that complexity should lead to instability.[2]
Degree distribution: the degree distribution of an ecological network is the cumulative distribution for the number of links each species has. The degree distributions of food webs have been found to display the same universal functional form. The degree distribution can be split into its two component parts, links to a species' prey (aka. in degree) and links to a species' predators (aka- out degree). Both the in degree and out degree distributions display their own universal functional forms. As there is a faster decay of the out-degree distribution than the in degree distribution we can expect that on average in a food web a species will have more in links than out links.[7]
Clustering: the proportion of species that are directly linked to a focal species. A focal species in the middle of a cluster may be a keystone species, and its loss could have large effects on the network.
Compartmentalization: the division of the network into relatively independent sub-networks. Some ecological networks have been observed to be compartmentalized by body size[8][9] and by spatial location.[10] Evidence also exists which suggests that compartmentalization in food webs appears to result from patterns of species' diet contiguity [11] and adaptive foraging [12]
Nestedness: the degree to which species with few links have a sub-set of the links of other species, rather than a different set of links. In highly nested networks, guilds of species that share an ecological niche contain both generalists (species with many links) and specialists (species with few links, all shared with the generalists).[13] In mutualistic networks, nestedness is often asymmetrical, with specialists of one guild linked to the generalists of the partner guild.[14] The level of nestedness is determined not by species features but overall network depictors (e.g. network size and connectance) and can be predicted by a dynamic adaptive model with species rewiring to maximize individual fitness[15] or the fitness of the whole community.[16]
In-block nestedness:[17] Also called compound structures,[18] some ecological networks combine compartmentalization at large network scales with nestedness within compartments.[19][20]
Trophic coherence: The tendency of species to specialise on particular trophic levels leads to food webs displaying a significant degree of order in their trophic structure, known as trophic coherence,[22] which in turn has important effects on properties such as stability and prevalence of cycles.[23]
Stability and Optimisation
The relationship between ecosystem complexity and stability is a major topic of interest in
Interaction strength may decrease with the number of links between species, damping the effects of any disturbance[26][27] and cascading extinctions are less likely in compartmentalized networks, as effects of species losses are limited to the original compartment.[10] Furthermore, as long as the most connected species are unlikely to go extinct, network persistence increases with connectance[28][29][30][31] and nestedness.[30][32][33][34] No consensus on the links between network nestedness and community stability in mutualistic species has however been reached among several investigations in recent years.[35] Recent findings suggest that a trade-off between different types of stability may exist. The nested structure of mutual networks was shown to promote the capacity of species to persist under increasingly harsh circumstances. Most likely, because the nested structure of mutualistic networks helps species to indirectly support each other when circumstances are harsh. This indirect facilitation helps species to survive, but it also means that under harsh circumstances one species cannot survive without the support of the other. As circumstances become increasingly harsh, a tipping point may therefore be passed at which the populations of a large number of species may collapse simultaneously.[36]
Other applications
Additional applications of ecological networks include exploration of how the community context affects pairwise interactions. The community of species in an ecosystem is expected to affect both the ecological interaction and
See also
- Biological network
- Consumer-resource systems
- Food web
- Pollination network
- Recycling (ecological)
Notes
- PMID 12235367.
- S2CID 4317192.
- PMID 12235364.
- JSTOR 1937073.
- ^ Briand, F. (1983). DeAngelis, D.L.; Post, W.M.; Sugihara, G. (eds.). Biogeographic Patterns in Food Web Organization. Tennessee: Oak Ridge National Laboratory, ORNL-5983. pp. 37–39.
- PMID 16954193.
- .
- .
- .
- ^ S2CID 1752696.
- PMID 21058554.
- PMID 25925104.
- PMID 24069264.
- PMID 12881488.
- PMID 21707903.
- S2CID 4412384.
- S2CID 1697222.
- hdl:10261/40471.
- S2CID 204540022.
- S2CID 195329102.
- PMID 17567558.
- ^ PMID 25468963.
- PMID 28512222.
- ^ Suweis, S., Grilli, J., Banavar, J. R., Allesina, S., & Maritan, A. (2015) Effect of localization on the stability of mutualistic ecological networks. "Nature Communications", 6
- ^ D. Garlaschelli, G. Caldarelli, L. Pietronero, (2003). Universal Scaling relations in food webs. "Nature" 423, 165
- Robert Poulin. (2007) Species abundance and asymmetric interaction strength in ecological networks. Oikos, 116; 1120-1127.
- ^ Suweis, S., Grilli, J., & Maritan, A. (2014). Disentangling the effect of hybrid interactions and of the constant effort hypothesis on ecological community stability. "Oikos", 123(5), 525-532.
- PMID 11571051.
- S2CID 2114852.
- ^ PMID 18070101.
- S2CID 4398165.
- PMID 15615687.
- S2CID 10258963.
- S2CID 206526054.
- S2CID 205078357.
- PMID 24386999.
References
Specific
- Bascompte, J.; Jordano, P.; Melian, C.J.; Olesen, J.M. (2003). "The nested assembly of plant-animal mutualistic networks". Proceedings of the National Academy of Sciences. 100 (16): 9383–9387. PMID 12881488.
- Burgos, E.; Ceva, H.; Perazzo, R.P.J.; Devoto, M.; Medan, D.; Zimmermann, M.; Delbue, A.M. (2007). "Why nestedness in mutualistic networks?". Journal of Theoretical Biology. 249 (2): 307–313. S2CID 10258963.
- Dunne, J.A.; Williams, R.J.; Martinez, N.D. (2002). "Network structure and biodiversity loss in food webs: robustness increases with connectance". Ecology Letters. 5 (4): 558–567. S2CID 2114852.
- Dunne, J.A.; Williams, R.J.; Martinez, N.D. (2002). "Food-web structure and network theory: The role of connectance and size". Proceedings of the National Academy of Sciences. 99 (20): 12917–12922. PMID 12235364.
- Krause, A.E.; Frank, K.A.; Mason, D.M.; Ulanowicz, R.E.; Taylor, W.W. (2003). "Compartments revealed in food-web structure" (PDF). Nature. 426 (6964): 282–285. S2CID 1752696.
- Memmot, J.; Waser, N.M.; Price, M.V. (2004). "Tolerance of pollination networks to species extinctions". Proceedings of the Royal Society of London B. 271 (1557): 2605–2611. PMID 15615687.
- Okuyama, T.; Holland, J.N. (2008). "Network structure properties mediate the stability of mutualistic communities" (PDF). Ecology Letters. 11 (3): 208–216. PMID 18070101.
- Pimm, S.L. (1984). "The complexity and stability of ecosystems". Nature. 307 (5949): 321–326. S2CID 4317192.
- Reuman, D.C.; Cohen, J.E. (2004). "Trophic links' length and slope in the Tuesday Lake food web with species' body mass and numerical abundance". Journal of Animal Ecology. 73 (5): 852–866. .
- Schmid-Araya, J.M.; Schmid, P.E.; Robertson, A.; Winterbottom, J.; Gjerlov, C.; Hildrew, A.G. (2002). "Connectance in stream food webs". Journal of Animal Ecology. 71 (6): 1056–1062. .
- Stouffer, D.B. (2010). "Scaling from individuals to networks in food webs". Functional Ecology. 24 (1): 44–51. .
- Sole, R.V.; Montoya, J.M. (2001). "Complexity and fragility in ecological networks". Proceedings of the Royal Society of London B. 268 (1480): 2039–2045. PMID 11571051.
- Vazquez, D.P.; Melian, C.J.; Williams, N.M.; Bluthgen, N.; Krasnov, B.R.; doi:10.1111/j.2007.0030-1299.15828.x (inactive 2024-02-07).)
{{cite journal}}: CS1 maint: DOI inactive as of February 2024 (link - Williams, R.J.; Berlow, E.L.; Dunne, J.A.; Barabasi, A.L.; Martinez, N.D. (2002). "Two degrees of separation in complex food webs". Proceedings of the National Academy of Sciences. 99 (20): 12913–12916. PMID 12235367.
- Zhang, F.; Hui, C.; Terblanche, J.S. (2011). "An interaction switch predicts the nested architecture of mutualistic networks". Ecology Letters. 14 (8): 797–803. PMID 21707903.
- Suweis, S.; Simini, F.; Banavar, J; Maritan, A. (2013). "Emergence of structural and dynamical properties of ecological mutualistic networks". Nature. 500 (7463): 449–452. S2CID 4412384.
- Lever, J. J.; Nes, E. H.; Scheffer, M.; Bascompte, J. (2014). "The sudden collapse of pollinator communities". Ecology Letters. 17 (3): 350–359. PMID 24386999.
General
- Bascompte, J (2007). "Networks in ecology". Basic and Applied Ecology. 8 (6): 485–490. hdl:10261/40172.
- Montoya, J.M.; Pimm, S.L.; Sole, R.V. (2006). "Ecological networks and their fragility". Nature. 442 (7100): 259–264. S2CID 592403.