Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The eco-evolutionary dynamics of complex adaptive food webs
Thesis (PhD)--Stellenbosch University, 2017.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University.
2017
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613912451514368 |
|---|---|
| access_status_str | Open Access |
| author | Nuwagaba, Savannah |
| author2 | Hui, Cang |
| author_browse | Hui, Cang Nuwagaba, Savannah |
| author_facet | Hui, Cang Nuwagaba, Savannah |
| author_sort | Nuwagaba, Savannah |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University. |
| description | Thesis (PhD)--Stellenbosch University, 2017. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/102639 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:40.919Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Stellenbosch : Stellenbosch University. |
| publisherStr | Stellenbosch : Stellenbosch University. |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/102639 The eco-evolutionary dynamics of complex adaptive food webs Nuwagaba, Savannah Hui, Cang Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences. UCTD Food chains (Ecology) -- Adaptation Ecological disturbances Predatory animals -- Body size -- Mathematical models Biocomplexity Coevolution Bifurcation theory Thesis (PhD)--Stellenbosch University, 2017. ENGLISH ABSTRACT: Predator-prey interactions are ubiquitous since almost every species on earth participates in at least one predator-prey interaction. As a result, they shape the food web structure, the functioning of ecosystems and the response to perturbations. Predator-prey interactions have been studied extensively. However, the interplay between their ecological and evolutionary dynamics and how these contribute to regulate food web dynamics have received less attention. In this thesis, therefore, I developed a predator-prey model in which the predator exhibited type II functional response, its body size could evolve and its handling time was dependent on predator-prey body size ratio. Using adaptive dynamics, a mathematical tool which has been developed to study feedback between ecological and evolutionary processes, I investigated the influence of non-linear functional response on the evolution of predator’s body size. I found that increasing handling time reduces the predator’s body size. In fact, there exists a threshold beyond which an increase in handling time drastically reduces the body size such that evolutionary regime shifts occur. I concluded that predators’ feeding rates, as influenced by the current climate trends, coupled with evolution, could explain the observed regime shifts in species body sizes. I extended this model to allow for polymorphism and showed that starting with a single prey and predator, food webs emerge through the process of mutation and natural selection. I checked the density-body size relationship in the emergent food webs to investigate the generality of the energetic equivalence rule and found no support for it. Instead, my results showed a hump-shaped relationship, except for food webs that were generated from the predators which exhibited the linear functional response. I further allowed potential invaders into co-evolving food weds to test how invasion success depends on species body size, propagule pressure, native species diversity and introduction time. I found that whenever potential invaders have a bigger body size, they always have a higher invasion success. In addition, I found that although the propagule pressure plays an important role, it is irrelevant in a diverse food web in which most or all niches have been occupied, hence strongly supporting the diversity-invasibility hypothesis. AFRIKAANS OPSOMMING: Predator - prooi-interaksies is alomtegenwoordig, aangesien byna elke soort op aarde deelneem aan ten minste een roofdier-prooi-interaksie. As gevolg hiervan vorm hulle voedselwebstruktuur, die funksionering van ekosisteme en die reaksie op versteurings. Predator-prooi-interaksies is omvattend bestudeer, maar die wisselwerking tussen hul ekologiese en evolusionêre dinamika en hoe dit bydra tot die regulering van voedselwebdinamika, het minder aandag gekry. In hierdie proefskrif het ons dus 'n roofdier-prooi-model ontwikkel waarin die roofdier tipe II funksioneel vertoon het. Sy liggaamsgrootte kan ontwikkel en die hanteringstyd is afhanklik van die verhouding tussen roofdiere-prooi en die liggaam. Met behulp van adaptiewe dinamika, is 'n wiskundige instrument ontwikkel om terugvoer tussen ekologiese en evolusionêre prosesse te bestudeer. Ons het die invloed van nie-lineêre funksionele reaksie op die evolusie van roofdier se liggaamsgrootte ondersoek. Ons het gevind dat toenemende hanteringstyd die liggaam se grootte van die roofdier verminder. Trouens, daar bestaan 'n drempel waaroor 'n toename in hanteringstyd die liggaamsmassa drasties verminder, sodat evolusionêre regime verskuiwings voorkom. Ons het die gevolgtrekking gekom dat roofvoerders se voedselsyfers soos beïnvloed deur die huidige klimaatneigings, tesame met evolusie, die waargenome regime verskuiwings in spesies liggaamsgroottes kan verduidelik. Ons het hierdie model uitgebrei om polimorfisme moontlik te maak en het getoon dat met die begin van 'n enkele prooi en roofdier, voedselwebs ontstaan deur die proses van mutasie en natuurlike seleksie. Ons het die verhouding tussen digtheid en liggaamsgrootte in die opkomende voedselwebs nagegaan om die algemeenheid van die energetiese ekwivalensiereël te ondersoek en het geen ondersteuning daarvoor gevind nie. In plaas daarvan het ons resultate 'n bultvormige verhouding getoon behalwe vir voedselwebs wat uit die roofdiere gegenereer is wat die lineêre funksionele reaksie vertoon het. Ons het verder potensiële indringers toegelaat om voedselwedings te gebruik om te toets hoe die inval sukses afhang van die grootte van die spesies, propagule druk, inheemse spesies diversiteit en inleidingstyd. Ons het gevind dat wanneer potensiële indringers 'n groter liggaamsgrootte het, hulle altyd 'n hoër inval sukses het. Daarbenewens het ons bevind dat hoewel die propagule druk 'n belangrike rol speel, dit irrelevant is in 'n uiteenlopende voedselweb waarin meeste of alle nisse beset is, en daarom die diversiteit-invasibiliteitshipotese sterk ondersteun. Doctoral 2017-11-17T09:02:58Z 2017-12-11T10:35:25Z 2020-01-02T03:00:08Z 2017-12 Thesis http://hdl.handle.net/10019.1/102639 en_ZA Stellenbosch University. x, 102 pages application/pdf Stellenbosch : Stellenbosch University. |
| spellingShingle | UCTD Food chains (Ecology) -- Adaptation Ecological disturbances Predatory animals -- Body size -- Mathematical models Biocomplexity Coevolution Bifurcation theory Nuwagaba, Savannah The eco-evolutionary dynamics of complex adaptive food webs |
| title | The eco-evolutionary dynamics of complex adaptive food webs |
| title_full | The eco-evolutionary dynamics of complex adaptive food webs |
| title_fullStr | The eco-evolutionary dynamics of complex adaptive food webs |
| title_full_unstemmed | The eco-evolutionary dynamics of complex adaptive food webs |
| title_short | The eco-evolutionary dynamics of complex adaptive food webs |
| title_sort | eco evolutionary dynamics of complex adaptive food webs |
| topic | UCTD Food chains (Ecology) -- Adaptation Ecological disturbances Predatory animals -- Body size -- Mathematical models Biocomplexity Coevolution Bifurcation theory |
| url | http://hdl.handle.net/10019.1/102639 |
| work_keys_str_mv | AT nuwagabasavannah theecoevolutionarydynamicsofcomplexadaptivefoodwebs AT nuwagabasavannah ecoevolutionarydynamicsofcomplexadaptivefoodwebs |