Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Within arthropods, inter-individual and inter-population variation is generally poorly explored for
physiological parameters. Such physiological variability is important, as it can provide insight into
the capacity for evolutionary adaptation and how animals may cope with anthropogenic climate
change. Insect vectors of human and animal diseases, such as tsetse flies (Diptera, Glossinidae)
which carry trypanosomes, are of particular interest. Predictions of tsetse fly (Glossina spp.) range
expansion, possibly paralleled by increased disease occurrence, have been made under future
climate scenarios. Moreover, since there are generally strong relationships between abiotic variables
(e.g. temperature and moisture availability), population dynamics, distribution and abundance,
determining the physiological mechanisms influencing such relationships has utility for predictive
modelling of spatial and temporal changes in tsetse fly distributions. I investigated physiological
variation among individuals and populations, focusing mainly on Glossina spp. but using other
arthropods to address certain issues. Specifically, I show the following: i) metabolic rate is
repeatable (intra-class correlation coefficient) within individuals, and may be influenced by several
factors such as age, gender, body mass and pregnancy; ii) while metabolic rate is repeatable within
individuals, it remains unaltered with acclimation to laboratory conditions from field collection; iii)
within a population, metabolic rate-temperature relationships are surprisingly invariant among
physiological states such as age, gender, feeding status, pregnancy and temperature acclimation; iv)
the magnitude of the effect of temperature acclimation differs among traits, in that upper thermal
tolerances respond less than lower thermal tolerances, while metabolic rate responds to heat but not
to cold. Water loss rate is relatively unresponsive to either treatment; v) plasticity can account for
most inter-population variation in physiological traits related to climatic stress resistance (e.g.
thermotolerances and desiccation rates) in the natural environment; vi) adult physiological
performance responds differently to developmental and adult acclimation, such that marked traitspecific
variation occurs, and combinations of both developmental and adult plasticity can result in
further alteration of adult performance. These results have implications for the evolution of stress
resistance to abiotic factors in these and other arthropods. I conclude by discussing the potential
physiological patterns linking population dynamics and abiotic factors, with particular reference to
tsetse flies. / AFRIKAANSE OPSOMMING: Binne arthropoda, is tussen-individu en tussen-bevolking variasie in die algemeen sleg bestudeer vir
fisiologiese parameters. Hierdie fisiologiese variasie is belangrik want dit kan insig gee in die mate
van evolusionêre aanpassing en hoe diere antropogenies klimaatsverandering kan hanteer. Dit is
veral belangrik in die geval van insekte wat mens- en diersiektes kan dra, soos tsetse vlieë (Diptera,
Glossinidae) wat trypanosome oordra. In die geval van tsetse vlieë (Glossina spp.) is voorspellings
vir verhoogde verspreiding, en gevolglik verhoogde siekte voorkoms, gemaak onder toekomstige
voorkoms klimaat senario’s. Verder, aangesien daar in die algemeen sterk verwantskappe tussen
abiotiese parameters (bv. temperatuur en water beskikbaarheid), bevolkingsdynamika, verspreiding
en voorkoms is, is die bepaling van die fisiologiese meganisme, wat ‘n invloed het op hierdie
verwantskappe, nuttig vir die voorspelling van tsetse oor spasie en tyd. Hier, met hoofsaaklik die
gebruik van Glossina spp., maar ook ander arthropoda wanneer dit nodig is, word navorsing wat
fisiologiese variasie tussen individue en bevolkings aanspreel voorgelê. Spesifiek, word dit gewys
dat i) metaboliese tempo is herhaalbaar (intra-klas korrelasie koeffisient) binne individue, alhowel
metaboliese tempo kan beinvloed word deur faktore soos ouderdom, geslag, liggaamsmassa en
swangerskap, ii) terwyl metaboliese tempo binne individue herhaalbaar is, verander dit nie met
akklimasie na laboratorium toestande vanaf versameling in die veld, iii) binne ‘n bevolking
metaboliese tempo-temperatuur verwantskappe is verbasend eenders tussen fisiologiese toestande
soos ouderdom, geslag, voeding staat, swangerskap en temperatuur akklimasie, iv) die grootte van
die effek van temperatuur akklimasie verskil tussen eienskappe, en die boonste termiese limiete
reageer minder as laer termiese limiete, terwyl metaboliese tempo reageer op hitte maar nie koue
nie, en waterverlies tempo is relatief terughoudend tot enige temperatuur toestand, v) buigbaarheid
kan die meeste van inter-bevolkingsvariasie in fisiologiese eienskappe van klimaatstres
weerstandsvermoë (termiese toleransie en uitdrogingstempo) in die natuurlike omgewing verklaar,
vi) volwasse fisiologiese prestasie reageer verskillend op ontwikkelende en volwasse akklimasie,
soveel dat eienskap-spesifieke variasie kan voorkom, en ‘n kombinasie van beide ontwikkelende en
volwasse buigbaarheid ‘n verskillende volwasse prestasie tot gevolg kan hê. Hierdie resultate het
implikasies vir die evolusie van weerstandsvermoë tot abiotiese faktore in hierdie en ander
arthropoda. Hierdie tesis word afgesluit met ‘n bespreeking van die moontlikke fisiologiese patrone
wat bevolkingsdinamika en abiotiese faktore kan verbind, met ‘n fokus op tsetse vlieë.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21763 |
| Date | 04 1900 |
| Creators | Terblanche, Jonathan Steed |
| Contributors | Chown, Steven L., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | x, 254 leaves : ill. |
| Rights | Stellenbosch University |
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