Thermal physiology, behaviour and fitness in the lizard Agama atra: exploring inter-individual variation in the context of environmental change
| dc.contributor.advisor | Clusella-Trullas, Susana | en_ZA |
| dc.contributor.advisor | Logan, Michael | en_ZA |
| dc.contributor.advisor | Streicher, Jeffrey | en_ZA |
| dc.contributor.author | Alujevic, Karla | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. | en_ZA |
| dc.date.accessioned | 2020-02-25T11:01:38Z | |
| dc.date.accessioned | 2020-04-28T15:15:36Z | |
| dc.date.available | 2020-02-25T11:01:38Z | |
| dc.date.available | 2020-04-28T15:15:36Z | |
| dc.date.issued | 2020-03 | |
| dc.description | Thesis (PhD)--Stellenbosch University, 2020. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Individuality in a wide range of fitness-related traits has been well documented in both vertebrates and invertebrates. Examining variation in ecologically relevant traits, and the functional integration of these traits, is a crucial step in understanding the evolution of complex phenotypes in nature. With selection acting on individual phenotypic variation, understanding the links between fitness related traits and their temperature dependence should provide insight into the maintenance of different ‘life-strategy’ phenotypes in different natural contexts. This thesis investigated intra-population variation in thermal dependence of physiological and behavioural traits as well as the linkages between intra-population phenotypic variation and microclimate in the southern rock agama lizard (Agama atra). Selection simultaneously acts upon suites of traits that interact to form multivariate phenotypes. Nevertheless, individual measures of performance are often examined in isolation. To identify patterns of inter-individual variation within and across traits, I examined patterns of variation in the thermal sensitivity of ecologically important physiological and performance traits (resting metabolic rate, water loss rate, sprint speed, running endurance and bite-force), in southern rock agamas. Results suggest that physiological and performance traits appear to exist as a complex phenotype and provide first evidence for the presence of correlations between individual thermal sensitivities of physiological and performance traits. Next, I investigated if behavioural traits are grouped within personality types in A. atra. The integration between thermal performance and personality has recently been incorporated within the thermal-behavioural syndrome (TBS) with the premise that thermal physiology drives individual behaviour. To test this hypothesis, I explored the relationship between behavioural traits (personality) and thermal performance, following the prediction of TBS. While the presence of both ‘behavioural types’ and ‘thermal types’ was found, the direction of correlations within TBS was mediated by body mass. The most comprehensive paradigm explaining the prevalence of animal personality is the pace- of-life-syndrome (POLS). Mixed support for the integration of traits within POLS in ectotherms could be attributed to the effect of abiotic factors that have the potential to mediate the relationship between physiological, performance and behavioural traits. To address this, I tested the effect of temperature on the covariation between physiology, performance and personality (i.e. POLS). Despite theoretical predictions, (thermal sensitivity of) resting metabolic rate did not drive variation in sprint speed and personality in the southern rock agama. However, thermal plasticity of boldness covaried with sprint speed plasticity in large males. Behavioural strategies are the primary mechanism by which many ectothermic species cope with the temperature change in their environments. Animals occupying territories with high frequencies of favourable thermal microclimates should incur lower thermoregulatory costs, and therefore, be able to invest more time into other important ecological tasks. To test these predictions, I investigated how thermal quality (estimated as the overlap between individual optimal thermal performance range and available operative temperatures within respective territories) affects accuracy of thermoregulation and behaviour of males in the study population. Results of this field study show that thermal quality of individual territories drives variation in body temperature, accuracy of thermoregulation and signalling behaviour of males in a population of southern rock agama lizards. An outstanding question of this research is how the interplay between thermal properties of territories, thermal performance characteristics and individual personality may shape the fitness of these lizards. To understand the mechanisms that shape organism fitness, this project aimed to estimate reproductive success of A. atra lizards using ddRAD sequencing and pedigree analyses, and link these results to individual thermal and behavioural ecology. While this approach offered various analytical challenges that require further research, preliminary analyses suggest the presence of substantial genetic variation and SNP heterozygosity in the study population. In addition, observed differences in mean pairwise genetic distances are consistent with physiological and performance traits being heritable. The results of these analyses thus far are encouraging for linking inter-individual variation in thermal physiology, performance, behaviour and territory thermal quality to individual reproductive output. This holistic approach will aid in understanding the mechanisms underlying lizard fitness but also how selection might drive adaptive evolution of thermal traits of ectotherms in the context of environmental change. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Individualiteit in 'n wye verskeidenheid fiksheidsverwante eienskappe is goed gedokumenteer in gewerweldes en ongewerweldes. Ondersoeking van variasie in ekologiese relevante eienskappe, en die funksionele integrasie van hierdie eienskappe, is 'n belangrike stap in die begrip van die evolusie van komplekse fenotipes in die natuur. Met seleksie wat op individuele fenotipiese variasie reageer, moet die verband tussen fiksheidsverwante eienskappe en hul temperatuurafhanklikheid insig gee in die instandinghouding van verskillende 'lewensstrategie' fenotipes in verskillende natuurlike kontekste. Hierdie tesis het die binne- populasie variasie in termiese afhanklikheid van fisiologiese en gedragseienskappe, asook die verband tussen binne-populasie fenopotiese variasie en mikroklimaat in die suidelike rotsagama-akkedis (Agama atra) ondersoek. Seleksie werk gelyktydig op groepe van eienskappe wat op mekaar reageer om meerveranderlike fenotipes te vorm. Nietemin word individuele maatstawwe van vermoë dikwels in isolasie ondersoek. Om patrone van tussen-individuele variasie binne en tussen verskillende eienskappe te identifiseer, het ek die variasiepatrone in die termiese sensitiwiteit van ekologiese belangrike fisiologiese en vermoëns (rustende metaboliese tempo, waterverlies, sprint spoed, hardloop-uithouvermoë en bytkrag) in die suidelike rotsagama ondersoek. Resultate dui aan dat fisiologiese-eienskappe en vermoëns voorkom as 'n komplekse fenotipe en lewer eerste bewys vir die teenwoordigheid van korrelasies tussen individuele termiese sensitiwiteite van fisiologiese-eienskappe en vermoëns. Ek het volgende ondersoek of gedragseienskappe binne die persoonlikheidstipes in A. atra gegroepeer is. Die integrasie tussen termiese vermoëns en persoonlikheid is onlangs in die termiese-gedragsindroom (TGS) geïnkorporeer met die veronderstelling dat termiese fisiologie individuele gedrag dryf. Om hierdie hipotese te toets, het ek die verband tussen gedragseienskappe (persoonlikheid) en termiese vermoëns ondersoek na aanleiding van die voorspelling van TGS. Terwyl die teenwoordigheid van beide 'gedragstipes' en 'termiese tipes' gevind is, is die rigting van korrelasies in die TGS bemiddel deur liggaamsmassa. Die mees omvattende paradigma wat die voorkoms van dierepersoonlikheid verklaar is die pas- van-lewe-sindroom (PVLS). Gemengde ondersteuning vir die integrasie van eienskappe binne PVLS in ektoterme kan toegeskryf word aan die effek van abiotiese faktore wat die verband tussen fisiologiese, vermoëns en gedragseienskappe kan bemiddel. Om hierdie te toets, het ek die effek van temperatuur op die samevariasie tussen fisiologie, vermoëns en persoonlikheid (d.w.s. PVLS) getoets. Ondanks teoretiese voorspellings, (termiese sensitiwiteit van) die rustende metaboliese tempo het nie variasie in sprint spoed en persoonlikheid in die suidelike rotsagama veroorsaak nie. Alhoewel, die termiese plastisiteit van lae risiko-afkeer word egter met die sprint-spoedplastisiteit van groot mannetjies gepaard. Gedragstrategieë is die primêre meganisme waardeur baie ektotermiese spesies die temperatuurverandering in hul omgewings hanteer. Diere wat gebiede beset met 'n hoë frekwensie van gunstige termiese mikroklimate, moet laer termoregulerende kostes inhou en daarom meer tyd in ander belangrike ekologiese take kan belê. Om hierdie voorspellings te toets, het ek ondersoek hoe die termiese kwaliteit (geskat as die oorvleueling tussen optimale termiese reekse van individue en beskikbare operasionele temperature binne die onderskeie gebiede) die akkuraatheid van termoregulering en gedrag van mannetjies in die studiepopulasie beïnvloed. Resultate van hierdie veldstudie wys dat die termiese kwaliteit van individuele gebiede die variasie in liggaamstemperatuur, akkuraatheid van termoregulering en seingedrag van mannetjies in 'n bevolking van suidelike rotsagama-akkedisse dryf. 'n Uitstaande vraag van hierdie navorsing is hoe die wisselwerking tussen termiese eienskappe van gebiede, termiese vermoëns en individuele persoonlikheid die fiksheid van hierdie akkedisse saam kan beïnvloed. Om die meganismes wat die fiksheid van organismes vorm beter te verstaan, het hierdie projek die doel gehad om voortplantingsukses van A. atra akkedisse te skat met behulp van ddRAD en stamboekontledings, en om hierdie resultate aan individuele termiese en gedragsekologie te koppel. Alhoewel hierdie benadering verskillende analitiese uitdagings bied wat verdere navorsing verg, dui voorlopige ontledings daarop dat daar aansienlike genetiese variasie en SNP-heterosigositeit in die studiepopulasie bestaan. Boonop, die verskille in gemiddelde paarsgewyse genetiese afstande is in ooreenstemming met die feit dat fisiologiese eienskappe erflik is. Die resultate van hierdie ontledings tot dusver is bemoedigend om tussen-individuele variasie in termiese fisiologie, vermoëns, gedrag en termiese kwaliteit van die gebied te koppel aan individuele voortplantingsproduksie. Hierdie holistiese benadering sal help om die meganismes onderliggend aan akkedis fiksheid beter te verstaan, maar ook hoe seleksie die adaptiewe evolusie van termiese eienskappe van ektoterme kan beïnvloed in die konteks van omgewingsverandering. | af_ZA |
| dc.description.version | Doctorate | en_ZA |
| dc.embargo.terms | 2023-02-01 | |
| dc.format.extent | xxi, 158 pages : illustrations, some color | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/108479 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject.lcsh | Agama -- Ecology | en_ZA |
| dc.subject.lcsh | Agama atra -- Behavior | en_ZA |
| dc.subject.lcsh | Agama-- Effect of temperature on | en_ZA |
| dc.subject.lcsh | Agamidae -- Phylogeny | en_ZA |
| dc.subject.lcsh | Lizards -- Population viability analysis | en_ZA |
| dc.subject.lcsh | Lizards -- Effect of global warming on | en_ZA |
| dc.subject.lcsh | Lizards -- Variation | en_ZA |
| dc.subject.lcsh | Cold-blooded animals -- Climatic factors | en_ZA |
| dc.subject.lcsh | Body temperature -- Regulation -- Data processing | en_ZA |
| dc.subject.name | UCTD | en_ZA |
| dc.title | Thermal physiology, behaviour and fitness in the lizard Agama atra: exploring inter-individual variation in the context of environmental change | en_ZA |
| dc.type | Thesis | en_ZA |