Structural Emergence in Mutualistic Networks
| dc.contributor.advisor | Hui, Cang | en_ZA |
| dc.contributor.author | Nnakenyi, Chinenye Assumpta | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences. | en_ZA |
| dc.date.accessioned | 2016-12-22T14:27:30Z | |
| dc.date.available | 2019-12-31T03:00:13Z | |
| dc.date.issued | 2016-12 | |
| dc.description | An article based on this thesis is available at https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.06053 | en_ZA |
| dc.description | Thesis (MSc)--Stellenbosch University, 2016. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Mutualistic interactions are vital in sustaining species, maintaining the functions and services of the ecosystem. Network structures such as nestedness and modularity have being reported to emerge as a result of the mutualistic interactions. Although these structures have being found to have effect in the stability of mutualistic communities, mechanisms that lead to the emergence of these structures are not fully understood. From the observed pollination data of 10 Galápagos Islands, we use a modified Lotka-Voltera model of mutualism that incorporates species competition, functional responses and adaptive rewiring (Adaptive Interaction Switching [AIS] model) to predict the observed network structures. From the AIS model, almost 40% variation of the observed nestedness and more than 50% variation of the observed modularity was explained. Furthermore, using a Generalized Linear Model (GLM), the effect of environmental variables such as geographic factors (island area, isolation, age and maximum elevation) and anthropogenic factors (sampling effort and human population size) were considered together with the AIS model. The GLM can account for more than 78% variation of the observed nestedness and more than 85% of the observed modularity, with island area, isolation, sampling effort and human population size the most important variables, contributing significantly to the observed network structures. Therefore, pollination networks on Galápagos Islands are structured. The AIS model implemented can explain an appreciable level of network structure. Together with environmental variables, the results echo the importance of island area and isolation (as of island biogeography), human disturbance, sampling effort, as well as the adaptive rewiring (ecological fitting), as a candidate model for mutualistic network emergence. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Mutualistiese interaksie is noodsaaklik vir die handhawing van spesies en die onderhoud van funksies en dienste van die ekosisteem. Netwerkstrukture soos genestheid en modulariteit is al berig om as 'n resultaat van sulke mutualistiese interaksies na vore te kom. Alhoewel hierdie strukture bevind is om 'n effek te hê op die stabiliteit van mutualistiese gemeenskappe, word meganismes wat lei tot die opkoms van hierdie strukture nog nie goed verstaan nie. Deur 10 bestuiwingsdata van die Galápagos-eilande the gebruik, het ons 'n aangepaste Lotka-Volterra model van mutualisme gebruik wat kompetisie tussen spesies, funksionele reaksies en aanpasbare herbedrading [rewiring] (Adaptive Interactive Switching [AIS] model) inkorporeer om die waargenome netwerkstrukture te voorspel. Uit die AIS model is byna 40% variasie van die waargenome genstheid en meer as 50% variasie van die waargenome modulariteit verduidelik. Verder, deur 'n Veralgemeende lineêre model (of GLM vir Generalized Linear Model) te gebruik, is die effek van geografiese faktore (eilandoppervlakte, isolasie, ouderdom en maksimum hoogte bo seespieël) en antropogeniese faktore (poging tot steekproefneming en menslike bevolkingsgrootte) saam met die AIS model in ag geneem. Die GLM kan tot 78% variasie van die waargenome genestheid en meer as 85% van die waargenome modulariteit verduidelik, met eliandoppervlakte, isolasie, poging tot steekproefneming en menslike bevolkingsgrootte die belangrikste veranderlikes wat aansienlik bydrae tot die waargenome netwerkstrukture. Daarom is netwerke op die Galápagos-eilande gestruktureerd. Die AIS model wat ons geïmplememteer het, kan 'n aansienlike vlak van netwerkstrukture verduidelik. Saam met omgewingsveranderlikes weerspieël die bevindings die belang van eilandoppervlakte en isolasie (soos van eiland biogeografie), menslike versteuring, poging tot steekproefneming sowel as aanpasbare herbedrading (ekologiese passing) as 'n kandidaatmodel vir mutualistiese netwerkopkoms. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.embargo.terms | 2020-11-31 | |
| dc.format.extent | xvii, 77 pages : illustrations | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/100423 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Mutualism (Biology) -- Mathematical models | en_ZA |
| dc.subject | System theory | en_ZA |
| dc.subject | Pollination -- Mathematical models | en_ZA |
| dc.subject | Biogeography -- Galapagos Islands | en_ZA |
| dc.subject | Nestedness | en_ZA |
| dc.subject | Modules (Algbra) | en_ZA |
| dc.subject | UCTD | |
| dc.title | Structural Emergence in Mutualistic Networks | en_ZA |
| dc.type | Thesis | en_ZA |
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