Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Physiological diversity in insects was investigated in terms of gas exchange patterns and metabolic rate. Since the majority of hypotheses that propose to explain the occurrence of Discontinuous Gas Exchange Cycles (DGCs) are adaptive, the possibility of adaptation was explored in two ways. First, since repeatability is one of the three prerequisites for natural selection, and rarely tested in insects, the repeatability of gas exchange characteristics and metabolic rate were tested in a Perisphaeria sp. cockroach. Four major gas exchange patterns were recognized and these patterns were found to be extremely variable within this species. However, repeatability was still generally high for the majority of the gas exchange characteristics and metabolic rate. Moreover, between individual variability generally accounted for a large proportion of the variance, supporting the repeatability findings. Therefore, both metabolic rate and gas exchange patterns might indeed be adaptive traits in this Perisphaeria sp. cockroach. Second, the distribution of the three gas exchange patterns (DGCs, cyclic and continuous) across the insect phylogeny was investigated. Data were extracted from the literature and gas exchange patterns for eight insect orders, representing mainly the endopterygotes, were measured. Using standard respirometry techniques, data for a total of ten additional orders were added, which represented both apterygote orders, six exopterygote orders and two endopterygote orders that were previously uninvestigated. In addition, four of the five adaptive hypotheses were tested by investigating the occurrence of DGCs in winged or wingless insects, subterranean and non-subterranean insects, and insects from mesic and xeric environments. Results indicate that DGC has evolved at least five times in the insects and that the cyclic gas exchange pattern is likely to be basal. No support was found for the chthonic, hybrid and oxidative damage hypotheses, while DGCs were associated with xeric environments. This analysis provides some support for the hygric hypothesis. In addition the prediction of the fractal network model for metabolic scaling which states that both intra- and interspecific scaling coefficients should be identical and equal to 0.75, was tested. Three species of polymorphic worker ants were used to determine the intraspecific scaling coefficient. Data from the literature were added to provide metabolic rate information on 42 species of the Formicidae. The interspecific scaling coefficient was determined in several ways: the traditional method (Ordinary Least Squares regression models), with the two respirometry techniques analyzed separately or in combination (e.g. open and closed system), and using phylogenetic independent contrasts with the same sets of data. Intraspecific coefficients were significantly different from 0.75. The slope of the interspecific regression obtained using Ordinary Least Squares regression models was not significantly different from 0.75. However, when phylogenetic relatedness was accounted for the slope differed significantly from 0.75. Therefore, the fractal network model was not supported by these findings, since slope values are not equal and also not statistically equivalent to 0.75. Overall, variability of both metabolic rate and gas exchange patterns in insects is higher than generally suggested by the literature. These findings provide much scope for future work. / AFRIKAANSE OPSOMMING: Hier word die fisiologiese diversiteit van insekte ondersoek in terme van hul gaswisselings patrone asook hul metaboliese tempo. Die oorgrote meerderheid van die hipoteses wat voorgestel is om die onstaan en bestaan van Diskontinue Gaswisseling in insekte te verklaar, is op ‘n evolusionêre grondslag gebaseer. Vir hierdie rede word die moontlikheid van Diskontinue Gaswisseling as ‘n aanpassing op twee maniere ondersoek. Herhaalbaarheid is een van die voorvereistes van aanpassing (in terme van evolusie) en dit is tot dusver slegs ‘n paar keer in insekte getoets is. Daarom word die herhaalbaarheid van die gaswisselings komponente, asook die metaboliese tempo hier in ‘n Perisphaeria sp. kokkerot ondersoek. Vier hoof gaswisselings patrone is geidentifiseer en die bevinding was dat die patrone geweldig kan varieer binne hierdie spesie. Ten spyte hiervan was die herhaalbaarheid steeds hoog vir die oorgrote meerderheid van die gaswisselings komponente asook vir die metaboliese tempo. Verder het die variasie tussen individue tot ‘n groot proporsie van die totale variasie bygedra, wat die betekenisvolheid van die hoë herhaalbaarheid beklemtoon. Dus, beide metaboliese tempo sowel as gaswisselings komponente kan moontlik as ‘n aanpassing beskou word in hierdie kokkerot. Tweedens, die verspreiding van die drie gaswisselings patrone (Diskontinue Gaswisseling, siklies en kontinu) in die insekte is ondersoek. Gaswisselings patrone vir agt van die dertig insek ordes is vanuit die literatuur verkry, alhoewel dit meestal verteenwoordigend van die Endopterygota is. Data vir tien additionele ordes wat nog nooit voorheen ondersoek is nie is bygevoeg, insluitende beide die ordes van Apterygota en ses ordes van die Exopterygota, asook twee ordes van die Endopterygota. Verder is vier van die vyf hipoteses met betrekking tot aanpassing ondersoek deur die teenwoordigheid van Diskontinue Gaswisseling in gevleuelde en ongevleuelde insekte, ondergrondse en bogrondse insekte, asook insekte van gematigde en droeë omgewings te ondersoek. Resultate dui aan dat Diskontinue Gaswisseling ten minste vyf keer onafhanklik in insekte onstaan het en dat die sikliese patroon heel moontlik basaal is. Die resultate bied geen ondersteuning vir die hipoteses wat gegrond is op gaswisseling in ondergrondse omgewing of oksidasie beskerming nie. Daar is wel ondersteuning vir die hipotese aangaande die rol van water verlies in die onstaan en onderhoud van Diskontinue Gaswisseling. Additioneel is daar ondersoek ingestel na die verwagting wat deur die fraktale netwerk model vir metaboliese glyskale gestel word, wat lui dat beide die binne- sowel as tussen-spesies koëffisiënte identies aan mekaar en gelyk aan 0.75 sal wees. Drie polimorfiese mier spesies is gebruik om die binne-spesies koëffisiënt te bepaal. Data vanuit die literatuur is hier bygevoeg en sodoende was informasie vir 42 mier spesies van die Formicidae beskikbaar. Verskillende metodes is gebruik om die tussen-spesies koëffisiënt te bepaal: die tradisionele metode (sg. “OLS”-regressie), met die twee tegnieke om metaboliese tempo te bepaal (bv. oop en geslote sisteem metodes) apart asook saam, en deur gebruik te maak van filogeneties onafhanklike vergelykings vir dieselfde datastelle. Die binne-spesies koëffisiënte was almal betekenisvol verskillend van 0.75. Die tussen-spesies regressie waar gebruik gemaak is van ‘n “OLS”-regressie model was nie betekensivol verskillend van 0.75 nie. Met filogenetiese verwantskappe egter in ag geneem, het die koëffisiënt wel betekenisvol verskil van 0.75. Dus word die fraktale netwerk model nie ondersteun deur hierdie studie nie, aangesien die koëffisiënte nie indenties aan mekaar is nie, en ook statisties verskil van 0.75. In die algemeen is die variasie in metaboliese tempo sowel as gaswisselings patrone aansienlik hoër as wat afgelei kan word uit die literatuur. Hierdie bevindinge stel ‘n basis vir heelwat verdere werk in die toekoms.

Thesis (MSc) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT: Standard histological procedures revealed that there are two types of glands in the cloacal complex of the viviparous Cordylus cataphractus. These occur in the urodeal region of the complex (called urodeal glands), and in the posterior proctodeum region (called proctodeal glands). Urodeal glands are found in females only and differentiate at sexual maturity. Proctodeal glands occur in both sexes and the dorsal and ventral proctodeal glands are identical in structure. Seasonal activity in cloacal gland structure and secretory was studied. Urodeal glands show distinct seasonal variation in development and secretory activity, they become enlarged in vitellogenic females, remain active during pregnancy, with glandular activity peaking around parturition. Proctodeal glands, in contrast, show little or no seasonal variation in development or secretory activity in both sexes. Secretion quantity, however, is highly variable among individuals of the same sex, time of year, as well as reproductive stage, but evidently much less in females than in males. Although the possible functions of the cloacal glands are still unclear, two main functions are suggested: a) mechanical function such as lubrication or a substrate for genital products and b) pheromonal communication. I propose that urodeal glands are involved in some reproductive function rather than in social communication, because very little secretion is found during the mating season and peak glandular activity are evident around parturition. The opposite may be true for proctodeal glands, but further investigation is needed, particularly chemical analysis of secretion and behavioural manipulation, to determine the role of these glands in social communication. / AFRIKAANSE OPSOMMING: Standaard histologiese tegnieke dui aan dat daar twee tipes kliere voorkom in die kloakale kompleks van die lewendbarende akkedis, Cordylus cataphractus. Die een kliertipe word in die urodeale omgewing aangetref en staan bekend as die urodeaalkliere, terwyl die ander groep in die posterior area van die proktodeum voorkom en proktodeaalkliere heet. Urodeaalkliere word slegs in wyfies aangetref en ontwikkel eers na volwassenheid bereik is. Proktodeaalkliere kom in albei geslagte voor en dorsale en ventrale aspekte van hierdie kliere is identies aan mekaar. Die seisoenale aktiwiteit in struktuur en sekresie-aktiwiteit van hierdie kloakale kliere is ondersoek in mannetjies en wyfies wat gedurende verskillende maande van die jaar versamel is en dus in verskillende voorplantingstadia was. Urodeaalkliere het duidelike seisoenale variasie vertoon wat beide ontwikkeling van die klier en sekretoriese aktiwiteite betref. Die klier vergroot tydens vitellogenese, bly aktief tydens swangerskap en bereik maksimale aktiwiteitsvlakke rondom geboorte. In teenstelling hiermee het die proktodeaalkiere van beide geslagte weinig of self geen seisonale variasie in hul ontwikkeling of sekretoriese aktiwiteit getoon nie. Die hoeveelheid sekreet vrygestel was merkbaar minder in wyfies as in mannetjies, maar hoogs veranderlik tussen individue van dieselfde geslag of voortplantingstadium; of wat in dieselfde tydperk van die jaar versamel is. Alhoewel funksies van kloakale kliere steeds onduidelik bly, word twee hooffunksies voorgestel: a) ‘n meganiese funksie, byvoorbeeld as smeermiddel of as ‘n substraat vir geslagsprodukte en b) ‘n kommunikasie funksie, byvoorbeeld in die vrystelling van feromone. Ek stel voor dat die urodeaalkliere eerder by ‘n voortplantingsfunksie betrokke is, aangesien baie min sekreet gedurende die paarseisoen vervaardig word terwyl klieraktiwiteit rondom geboorte ‘n piek bereik. Die teenoorgestelde mag geld vir proktodeaalkliere, maar vereis verdere ondersoek. Veral ‘n chemiese analise van die sekresie en gedragsmanipulasie sal nuttig wees om ‘n moontlike rol van hierdie kliere in sosiale kommunikasie te bepaal.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: There is overwhelming evidence that the Armadillo Lizard, Cordylus cataphractus, forms permanent aggregations, and that termites are possibly the most important component of the diet of this species. In addition, the spinose morphology and defensive tail-biting behaviour displayed by this lizard species strongly imply that individuals move away from the crevice, where they are more vulnerable to predation. Therefore the aim of this part of the study was to investigate whether C. cataphractus harvest termites at the termite foraging ports and to discuss the likely ecological implications of termitophagy for this species. A quadrate at the Graafwater study site, including several crevices housing C. cataphractus groups, was measured out. All the foraging ports of the subterranean harvester termite (Microhodotermes viator) present in the quadrate, were located and their positions recorded in respect to the distance from the nearest crevice housing lizards. The presence of C. cataphractus tracks at the foraging ports was used to verify whether individuals visited specific termite foraging ports. Tracks were found at foraging ports located at an average distance of 6.1 m, but were also located at foraging ports up to 20 m from the nearest crevice. The results strongly support the hypothesis that C. cataphractus individuals move away from the crevice to feed on termites. Termitophagy and the heavy armature of C. cataphractus appear to be key factors in the group-living behaviour of this species. Termitophagy allows individuals to live in groups as competition for food at the home crevice will be limited. Theheavy armature of C. cataphractus renders it clumsy and slow-moving, compared to other cordylids. Group-living will, however, eliminate juvenile dispersal and mate-searching excursions, activities which, in the light of the heavy morphology of the species, may result in high predation impact. The global objective of the study was to investigate social structure and space-use in Cordylus cataphractus. For the correct interpretation of data on the latter, it was necessary to first establish an ethogram for the study animal. Members of a multi-male group located at the Graafwater site, including all age-sex classes, were observed in the field by telescope, for a total of 102 hours. All individuals were observed to predominantly display maintenance behavioural act systems, however, agonistic act systems were also observed. Aggression levels were determined for the respective agonistic behavioural acts observed. Males were highly aggressive and displayed the most aggression (67.42 %). Females and sub-adults displayed aggression for 34.97 % and 37.75 % of the total observation time, respectively. Juveniles did not display aggression at all. Mating behaviour was also observed and described. An ethogram was thus established for the first time for C. cataphractus, and was compared to the ethograms available for a few other cordylids. The spatial distribution of individuals within a population has an important impact on the social structure that ensues. Living in a group imposes several pressures on the individual and competition for mates is one. The main aim of the study was to determine the space-use of all theindividuals included in a multi-male Cordylus cataphractus group (n = 55), to elaborate on the mating system. Specific focus was on the adult males and females of the multi-male group, because, ultimately, the manner in which individuals, particularly the adult males and females, utilise space, determines the mating system. The mating system is an important aspect of social structure. A two-dimensional grid pattern was delineated at a free-living, multi-male group’s crevice, situated at the Graafwater study site, to be able to plot the position of each individual during observations. All marked individuals, that were visible, were scanned through a telescope and their respective positions were recorded at 30-minute intervals. Arcview 3.2 Geographical Information Software was used to create a computerised model replicate of the two-dimensional grid pattern at the crevice, and to graphically depict the recorded positions for each individual. The space-use of males overlapped greatly with the space-use of females (66.12 ± 31.81 %), but a 0 % overlap in space-use was observed among adult males. The space-use of sub-adults and juveniles overlapped highly among one another, as well as with the space-use of adult males and females. The results showed conclusively that adult male C. cataphractus are territorial, defending specific sites at the crevice. The territory of each male included in the multi-male group incorporated at least one female. The space-use of several females incorporated the space-use of two or more males. Males were observed to mate with one or more females, and one female was observed to mate with two different males on more than one occasion. Thus the evidence strongly suggests that C. cataphractus males display typical territorial polygyny whereas females may be promiscuous. / AFRIKAANSE OPSOMMING: Daar is oorweldigende bewyse dat die pantsergordelakkedis, Cordylus cataphractus, permanent in groepe bly en dat termiete waarskynlik die belangrikste komponent in die dieet van hierdie spesie is. Die stekelrige morfologie en die stert-byt beskermingsgedrag is verder sterk aanduidings dat hierdie akkedisse tyd weg van hul klipskeure spandeer waar hulle meer gevoelig vir predasie is. Die doelwit van die eerste deel van die studie was om te bepaal of C. cataphractus termiete by die voedingspoorte van die termietneste oes en verder ook om die moontlike ekologiese implikasies wat termitofagie vir die spesie inhou, te bespreek. ‘n Kwadraat was by die Graafwater studielokaliteit uitgemeet om verskeie akkedisgroepe in te sluit. Al die voedingspoorte van die suidelike grasdraer termiet (Microhodotermes viator) binne die kwadraat is gevind en die afstande na die naaste klipskeur wat akkedisse huisves, is vir elke voedingspoort bepaal. Die teenwoordigheid van C. cataphractus spore in die sand by die voedingspoorte was gebruik om besoeke aan spesifieke voedingspoorte te bevestig. Spore is by voedingspoorte gemiddeld 6.1 m vanaf die naaste akkedisgroep gevind, maar tot so ver as 20 m vanaf die naaste akkedisgroep. Die resultate verleen sterk ondersteuning vir die hipotese dat C. cataphractus individue op termiete weg van hul klipskeur af voed. Termitofagie en die swaar pantser van C. cataphractus is waarskynlik sleutelfaktore in die groeplewe-gedrag van die spesie. Termitofagie laat groeplewe toe omdat kompetisie vir voedsel by die klipskeur beperk sal wees. Die swaar pantser van C. cataphractus het tot gevolg dat die spesie lomp en stadig is in vergelyking met ander gordelakkedisse. Groeplewe sal egter natale spreiding en maatsoek-ekskursies, aktiwiteite wat in die lig van die lompheid van die spesie swaar predasie impak tot gevolg kan hê, uitskakel. Die oorhoofse doelwit van die studie was om die sosiale struktuur en spesifiek ruimtebenutting by C. cataphractus te ondersoek. Vir korrekte interpretasie van data oor lg. was dit egter eers nodig om ‘n etogram vir die studiedier saam te stel. Lede van ‘n multi-mannetjie groep, wat alle ouderdomsgrootte klasse ingesluit het, is by die Graafwater studielokaliteit m.b.v. ‘n teleskoop vir ‘n totaal van 102 uur dopgehou. Al die individue in die groep het oorwegend instandhoudingshandelingsisteme vertoon, alhoewel agonistiese handelingsisteme ook vertoon is. Aggressievlakke is vir die verskeie agonistiese gedragshandelings bepaal. Mannetjies was hoogs aggressief en het die meeste aggressie vertoon (67.42 %). Wyfies en subvolwassenes het aggressie vir 34.97 % en 37.75 % van die totale observasietyd respektiewelik getoon. Jong individue het geen aggressie getoon nie. Paringsgedrag was ook waargeneem en beskryf. ‘n Etogram is dus vir die eerste keer vir C. cataphractus opgestel en is ook vergelyk met etogramme van ander gordelakkedisse. Die ruimtelike verspreiding van individue binne ‘n populasie het ‘n belangrike invloed op die sosiale struktuur wat daaruit voortvloei. Om in ‘n groep te lewe, plaas verskeie drukke op die individue binne die groep en kompetisie vir maats is een hiervan. The hoofdoelwit van die studie was om die ruimtebenutting van al die individue binne ‘n multi-mannetjie groep van C. cataphractus (n = 55) te bepaal en om die paringsisteem in so ‘n groep te ondersoek. Die spesifieke fokus was op die volwasse mannetjies en wyfies, omdat die paringsisteem deur die wyse waarop volwasse individue ruimte benut, bepaal word. Die studie is by die Graafwater studielokaliteit gedoen. Die oppervlak buite ‘n klipskeur wat deur ‘n multi-mannetjie groep bewoon word is opgedeel in sektore om die kartering van die posisies van die individue tydens observasietye moontlik te maak. Al die individue is vooraf met verfkodes langs die kant van die kop gemerk en op gegewe observasiedae is individuele posisies elke 30 min aangeteken. Arcview 3.2 Geographical Information Software was gebruik om ‘n tweedimensionele, gerekenariseerde replikaat van die klipskeur en onmiddelike omgewing te skep en om die waargenome posisies van individue grafies voor te stel. Die ruimtebenutting van mannetjies het grootliks met dié van wyfies oorvleuel, terwyl zero oorvleueling tussen mannetjies waargeneem is. Ruimtebenutting van subvolwasse en jong individue het ook grootliks onderling oorvleuel en ook met dié van volwasse mannetjies en wyfies. Die resultate toon duidelik aan dat volwasse mannetjies territoriaal is en dat spesifieke standplase rondom die klipskeur verdedig word. Die territorium van elke volwasse mannetjie het of ‘n gedeelte of die hele ruimtebenutting van ten minste een volwasse wyfie ingesluit. Ruimbenutting van verskeie wyfies het met dié van twee of selfs meer mannetjies oorvleuel. Mannetjies is waargeneem om met meer as een wyfie te paar en ten minste een wyfie het met meer as een mannetjie gepaar. Die resultate dui dus sterk daarop dat C. cataphractus mannetjies tipies terrotoriale poligenie vertoon terwyl wyfies weer promisku is.

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Many territorial carnivores deposit faeces and other scent-marks at specific latrine sites, and their role in territorial defence is often assumed. However, recent empirical and theoretical work suggests that ultimate explanations of territoriality differ between the sexes. In this thesis, I investigate patterns of latrine-use in cooperatively breeding meerkats, Suricata suricatta. Meerkats exhibit high reproductive skew, and in such societies an individual’s optimal investment in territory defence and intruder deterrence will depend not only on its sex, but also its breeding status within the group. The spatial and temporal distribution of meerkat latrines reflects the diversity in intruder type. Shared latrine sites between neighbouring groups facilitate costeffective monitoring of predictable intruders and surrounding land tenure. In contrast, intruding transient groups and prospecting males are effectively intercepted by latrines concentrated in the core of the territories, close to refuges. This represents the optimal strategy, as meerkat territories are too large to allow effective scent-marking around their entire peripheries, and these intruders travel between refuges during intrusions. Temporal patterns of latrine-use suggest their importance in mate-defence. Latrine-use was correlated with encounters with prospecting males and oestrous periods of resident females, and reached a peak coinciding with the season of elevated dispersal and take-over events. Additionally, rather than cooperatively contributing to territorial defence, individuals participated selfishly at latrines. Males preferentially over-marked female scent-marks and scent-marked at significantly greater rates than females, which resulted in male-biased latrines that were unrepresentative of group composition. Although all individuals investigated female scent-marks for significantly longer than male scent-marks, females invested most, suggesting that intra-group monitoring is an important aspect of latrine visits for females. The deleterious effects of close inbreeding are well known, but regular dispersal in both sexes, and long dominance tenure, result in unfamiliar siblings having a high probability of encountering one another post-dispersal. As latrines are implicated in mate-defence, olfactory assessment of factors affecting mating decisions might be expected, but although individuals do recognise foreign faeces, discrimination does not appear to occur on the basis of kinship. Together, these findings have broad implications for our understanding of individual variation and sex differences in scent-marking behaviour and territoriality. / AFRIKAANSE OPSOMMING: Baie territoriale karnivore deponeer faeces en ander reukmerke by spesifieke latrines en die latrines se rol in gebiedsverdediging word dikwels aangeneem. Onlangse empiriese en teoretiese werk stel egter voor dat die uiteindelike verduidelikings van territorialiteit verskil tussen die geslagte. In hierdie tesis ondersoek ek patrone van latrine-gebruik in samewerkend-broeiende meerkaaie (Suricata suricatta). Meerkaaie toon ‘n hoë graad van voorkeuraanwas en in sulke gemeenskappe sal ‘n individu se optimale belegging in gebiedsverdediging en indringer-verjaging nie net van sy/haar geslag afhang nie, maar ook van sy/ haar teelstatus in die groep. Die ruimtelike en temporale verspreiding van meerkat latrines weerspieël die verskeidenheid van indringertipes. Gedeelde latrine areas tussen naburige groepe help die kosteeffektiewe bestekopname van voorspelbare indringers en omringende landsbesetting aan. In kontras hiermee word tydelike groepe en geleentheidsoekende mannetjies effektiewelik voorgekeer deur latrines wat gekonsentreer is in gebiedskerne, naby aan skuilplekke. Dit verteenwoordig die optimale strategie, aangesien meerkat territoriums te groot is om effektiewe reukmerking van die hele grens toe te laat, en synde hierdie indringers tussen skuilplekke reis tydens invalle. Tydspatrone van latrine-gebruik dui die belangrikheid hiervan in paarmaat-beskerming aan. Latrinegebruik korreleer met ontmoetings met geleentheidsoekende mannetjies en die oestrus tydperk van inwonende wyfies, en bereik ‘n toppunt tydens die seisoen van verhoogde verspreiding en oornames. Ook sal individue selfsugtig deelneem by latrines eerder as om samewerkend by te dra tot gebiedsverdediging. Mannetjies verkies om vroulike reukmerke oor te merk en reukmerk teen ‘n beduidend hoër koers as wyfies, wat lei tot mannetjie-geneigde latrines wat nie verteenwoordigend is van die groepsamestelling nie. Alhoewel alle individue vroulike reukmerke beduidend langer as manlike reukmerke ondersoek, belê wyfies die meeste, wat daarop dui dat intragroep monitering ‘n belangrike aspek van latrine-besoeke is vir wyfies. Die nadelige effekte van sterk inteling is goed bekend, maar gereelde verspreiding in beide geslagte en lang dominante posisiehouding lei daartoe dat daar ‘n groot kans is vir onbekende nabye familielede om mekaar te ontmoet na verspreiding. Aangesien latrines ‘n rol speel in paarmaat-verdediging kan dit verwag word dat daar olfaktoriese beoordeling sal wees van faktore wat paringsbesluite beïnvloed, maar hoewel individue wel vreemdelinge se faeces herken, toon hulle geen onderskeidingsvermoë gebaseer op verwantskap nie. Saamgevoeg, het hierdie bevindinge wye implikasies vir ons begrip van individuele variasie en geslagsverskille in reukmerk-gedrag en terriorialiteit.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Smoothhound sharks Mustelus mustelus (Chondrichthyes: Triakidae) were conditioned to associate a compound auditory and electrical conditioned stimulus (CS) using the presentation of food as the unconditioned stimulus (US). This was done to investigate the general conditioning process of sharks, specifically the use of conditioned stimuli, the time frame required for conditioning, the retention of conditioned responses and the individual learning capabilities of sharks in classical conditioning experiments. Conditioning was done in two CS experiment replicates, in which the CS and the US were paired to elicit a conditioned response (CR: entering of a feeding area). Shark behaviour in these replicates was compared with those of sharks in a CS control. In the CS control, the CS and US were not paired; consequently no CS-US association was formed. In contrast, half of the sharks in the 1st and 2nd CS replicates formed the conditioned CS-US association after five and six days of conditioning training, respectively. This conditioned association was also retained over a two-month rest period. However the rate of conditioning of sharks varied, which was thought to be due to differences in motivational drives, particularly hunger. These experiments demonstrated that classical conditioning could provide a mechanism whereby smooth hound sharks can adapt to utilise new food sources. However these experiments could not demonstrate whether auditory or electrical cues are more biological relevant signallers of the presence of food for smooth hound sharks. According to the "belonging ness" phenomenon, for conditioning to be successful, the CS should be biologically relevant to the US. Therefore by comparisons of the conditioning success with different conditioned stimuli, the biological relevance of each CS can be determined. To determine the biological relevance of each component of the compound CS, an auditory or electrical CS was paired with the presentation of food (US), in separate experiments. The conditioned CS-US association formed in the majority of the sharks after 60 and 57 conditioning trials in the auditory CS and electrical CS experiment, respectively. This suggests that both auditory and electrical cues are biologically relevant signallers of food, facilitating the oppurtunistic feeding behaviour of smoothhound sharks. However, after five days of conditioning, conditioning with the electrical CS had proceeded further and the electrical CS-US association was stronger than the auditory CS-US association. This indicates that electrical cues are more biologically relevant due to past feeding experiences. Thus, classical conditioning during past feeding experiences can influence the feeding behaviour of smooth hound sharks. / AFRIKAANSE OPSOMMING: Gladde-hondhaaie Muste/us muste/us (Chondrichthyes: Triakidae) is gekonditioneer om "n gekombineerde klank en elektriese konditionerings stimulus (CS) met voedsel, die ongekonditioneerde stimulus (US) te assosieer. Dit is gedoen om die konditionerings proses, spesifiek die gebruik van konditionerings stimuli, tyd benodig vir konditionering, behoud van die gekonditioneerde gedrag en individuele leer-vermoëens van haaie in klassieke konditionerings eksperimente te ondersoek. Konditionering is gedoen in twee CS eksperiment replikate, waarin die CS en die US saam aangebied is, om "n konditionerings reaksie (CR: om in 'n voedings area in te beweeg) teweeg te bring. Die gedrag van haaie in die CS replikate is vergelyk met die van haaie in "n CS kontrole. In die CS kontrole is die CS en die US nie saam aangebied nie en gevolglik is geen gekonditioneerde CS-US assosiasie gevorm nie. Daarenteen is die CS-US assosiasie by die helfte van die haaie in die 1st en 2de CS replikate gevorm, na vyf en ses dae, onderskeidelik. Hierdie gekonditioneerde CS-US assosiasie het selfs behoue gebly na 'n twee maande rus periode. Die tempo van konditionering het egter verskil, moontlik a. g. v. motiverings verskille, veral hongerte. Hierdie eksperimente het gedemonstreer dat klassieke konditionering kan dien as 'n meganisme waarmee gladde-hondhaaie kan aanpas om nuwe voedsel bronne te benut. Hierdie eksperimente kon egter nie demonstreer óf klank stimuli óf elektriese stimuli meer biologiese relevante seine van die teenwoordighied van voesel is vir gladdehondhaaie nie. Volgens die "belonging ness" verskynsel, moet die CS biologies relevant to die US wees, vir konditionering om suksesvol te wees. Dus kan die biologiese relevansie van verskillende konditionerings stimuli bepaal word deur die konditionerings sukses van elke CS te vegelyk. Om die meer biologiese relevante komponent van die gekombineerde CS te bepaal, is 'n klank of elektriese CS saam met voedsel aangebied in aparte eksperimente. Die gekonditioneerse CS-US assosiasie is gevorm by die meeste van die haaie na 60 en 57 konditionerings proeflopies in die klank en elektriese CS eksperimente, onderskeidelik. Hierdie resultate dui daarop dat beide klank en elektriese stimuli biologies relevante siene van voedsel is, wat die oppurtunistiese voedings wyse van gladde-hondhaaie fasiliteer. Konditionering met die elektriese CS het egter verder gevorder en die elektriese CS-US assosiasie was sterker as die klank CSUS assosiasie na vyf dae van konditionering. Dus, mag elektriese stimuli meer biologies relevant wees weens vorige voedings ervaringe. Dit illustreer dat klasseke konditionering tydens vorige voedings ervaringe die voedings gedrag van gladde-hondhaaie kan beinvloed.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The alarm calls of a colonial rodent, Brants' whistling rat (Parotomys brantsii), were investigated at Goegap Nature Reserve in the Northern Cape, South Africa. At this site P. brantsii occurs in sympatry with the congeneric P. littledalei, and the alarm calls in response to humans was compared between the two species. Parotomys brantsii's typical call in reaction to a human is a simple whistle, characterized by an initial upward frequency sweep and high frequency plateau, whereas the alarm whistle of P. littledalei has three overlapping components. Parotomys littledalei's calls are significantly shorter and lower in dominant frequency than those of P. brantsii, and have a significantly wider frequency bandwidth. These distinctions were attributed to species discrimination and habitat preferences. The acoustic adaptation hypothesis is supported in part, as P. littledalei, which inhabits a closed habitat in comparison with P. brantsii, has calls which are lower in frequency than P. brantsii calls, but contrary to the hypothesis, P. brantsii calls show less frequency modulation than those of P. littledalei. The high pitch of both species' vocalizations may be a convergent feature making the callers difficult for predators to locate. The alarm call repertoire of P. brantsii was investigated by presenting members of the P. brantsii colony with models of some typical predators, a raptor and puff adder, as well as a human observer. Virtually no variation was detected in the structure of alarm whistles elicited by different predators, indicating that P. brantsii did not identify different predator types by means of vocalizations, even though behavioural responses showed that P. brantsii do distinguish between different predators and non-predators. Note duration varied in conjunction with the physical reaction of the caller. When the caller bolted towards safety, the whistle was significantly shorter than when it remained aboveground. During an encounter with a snake or far-off human the caller would utter relatively long duration calls, signifying a low-risk situation, while highrisk situations such as a nearby human or raptor provoked short calls, emitted just before the whistling rat bolted underground. I regard P. brantsii's alarm call repertoire as a graded "urgency-based" system, indicating threat level perceived rather than predator type. This system is widespread among ground squirrels and is usually associated with animals inhabiting a two-dimensional environment. Playback experiments were conducted to determine the meaning of alarm calls to conspecifics, focusing specifically on the effect of variation in single call duration and function of alarm-calling bouts. All alarm calls induced heightened vigilance in receivers, but the behavioural response did not differ between short and long single calls. Multiple calls lead to significantly longer periods of high vigilance than single calls even after calling bouts have ended, showing that one of the functions of multiple calls is to maintain high vigilance in conspecifics for relatively long periods. The non-iconic nature of their alarm calls and the undiscriminating response of receivers to different calls emphasizes the importance of contextual clues in the communication system of animals living in an open habitat like that of P. brantsii. / AFRIKAANSE OPSOMMING: Die alarm-roepgeluide van 'n koloniale knaagdier, Brants se fluitrot (Parotomys brantsii), is ondersoek by Goegap Natuurreservaat in the Noordkaap, Suid-Afrika, waar hulle simpatries voorkom met die naverwante P. littledalei. Die species se alarmroepe in reaksie op mense is met mekaar vergelyk. Die tipiese alarmroep van P. brantsii is 'n eenvoudige fluit, gekenmerk deur 'n aanvanklike skerp frekwensiestyging en hoë-frekwensie plato. Parotomys littledalei se fluitroep het drie komponente wat mekaar gedeeltelike oordek. Parotomys littledalei se roepgeluide is beduidend korter en laer in heersende toonhoogte as dié van P. brantsii, en hul frekwensie-wydte is ook beduidend wyer. Hierdie verskille word toegeskryf aan species-verskille en habitat-voorkeure. Die akoestiese aanpassingshipotese word gedeeltelik deur die studie ondersteun, aangesien P. littledalei, wat 'n geslote habitat verkies in vergelyking met P. brantsii, alarmroepe het met 'n laer dominante toonhoogte as P. brantsii. In teenstelling met die hipotese, toon P. brantsii se fluitgeluide minder frekwensie-modulasie as P. littledalei se geluide. Die hoë toonhoogte van beide species se alarmroepe kan 'n konvergente verskynsel wees wat dit vir roofdiere moeilik maak om fluitende individue te lokaliseer. Die alarm-repertoire van P. brantsii is ondersoek deur individue bloot te stel aan 'n menslike waarnemer en modelle van tipiese predatore, naamlik 'n jakkalsvoël en pofadder. Daar was omtrent geen variasie in die klank-struktuur van alarmroepe in reaksie op verskillende roofdiere nie. Dit wys daarop dat P. brantsii nie roofdiere deur middel van roepgeluide klassifiseer nie, hoewel gedragsresponse getoon het dat individue wel tussen roofdiere kan onderskei. Die duur van alarmroepe varieer na gelang van die gedrag van die fluitende individue - 'n fluitrot wat vlug, se roep is beduidend korter as die geluid van een wat bogronds bly. 'n Pofadder en 'n veraf mens ontlok lankdurende geluide, wat dui op 'n lae-risiko situasie, terwyl rotte op vlug slaan in reaksie op 'n hoë-risiko situasie, soos met 'n nabygeleë mens of jakkalsvoël, wanneer kort alarmroepe geuiter word. Ek beskou P. brantsii se alarmrepertoire as 'n gegradeerde "nood-gebaseerde" stelsel, wat die mate van bedreiging aandui, eerder as die identiteit van die spesifieke roofdier. Hierdie sisteem is tipies van grondeekhorings en word gewoonlik verbind met diere wat 'n twee-dimensionele omgewing bewoon. Parotomys brantsii se reaksie op die terugspeel van die species se geluide is hierna ondersoek. Ek het gefokus op die effek van 'n verandering in die duur van alleenstaande fluitnote, asook hulle reaksie op fluitreekse. Alle alarmroepe het gelei tot hoër vlakke van waaksaamheid in luisterende individue, maar reaksies op kort en lang enkelnote het nie van mekaar verskil nie. Fluitreekse het beduidend langer periodes van hoë waaksaamheid veroorsaak as enkele geluide, en waaksaamheid het hoog gebly selfs nadat reekse geëindig het. Dit beteken dat fluitreekse onder andere die funksie vervul om waaksaamheid in kolonielede vir relatief lang tye te onderhou. Parotomys brantsii se eenvoudige alarm-repertoire en nie-onderskeidende reaksie op verskillene roepgeluide, beklemtoon die belangrikheid van aanvullende inligting uit die omgewing vir diere in 'n twee-dimensionele habitat wanneer die akoestiese kommunikasiestelse slegs 'n algemene waarskuwingsfunksie vervul.

Thesis (PhD)--Stellenbosch University, 1972. / ENGLISH ABSTRACT: See item for full text

Thesis (PhD (Botany and Zoology))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The Rattus sensu lato complex, which harbours the important biomedical model species Rattus norvegicus, represents a group of rodents that are of clinical, agricultural and epidemiological importance. This study presents a comprehensive comparative molecular cytogenetic investigation of this complex. Karyotypes of 11 Rattus s. l. species and Hapalomys delacouri were analysed using conventional cytogenetic techniques. These data suggest that, contrary to previous claims, the usefulness of karyotypes for identifying these Asian murid species is limited, as few species-specific chromosomal characters could be identified. In order to understand the events that shaped the morphology and composition of the extant karyotypes, nine out of the 11 Rattus s. l. species were analysed by chromosome painting. This allowed the detection of a rare convergent sex-autosome translocation present in H. delacouri and B. savilei, whose establishment is hypothesised to have been favoured by the presence of interstitial heterochromatic blocks (IHBs) at the boundaries of the translocated segments. These results indicate that Rattus s. l. is characterised by slow to moderate rates of chromosome evolution in contrast to the extensive chromosome restructuring identified in most other murid rodents. Based on these data the first comprehensive putative Rattini ancestral karyotype was constructed. Their integration with published comparative maps enabled a revision of the previously postulated ancestral murid karyotype. BAC-mapping unequivocally demonstrated that the widely reported polymorphisms affecting chromosome pairs 1, 12 and 13 in the Rattus karyotypes are due to pericentric inversions. The analysis of genomic features, such as telomeres, Ag-NORs and satellite DNA suggest a constrained pattern of chromosome evolution. The investigated rat satellite I DNA family appears to be taxon (Rattus) specific, and of recent origin (consistent with a feedback model of satellite evolution). The comparative nature of the study led to the further analysis of the species within Rattus s. l. complex and their possible involvement as reservoirs of scrub typhus using a qPCR gene expression approach based on real-time PCR. The structure and transcription of syndecan-4, which had previously been linked to Orientia tsutsugamushi (causative agent of scrub typhus) infection, was compared among Rattini (typhus-positive) and Murini (typhus-negative) rodents. Although, it was not possible to conclusively link the structural variation observed between Rattini and Murini with carrier status, a link was identified between underexpression of syndecan-4 in Murini and seropositive Rattini rodents, compared to those that were seronegative. This suggests that the reduced levels of syndecan-4 transcription in Murini and Rattini is linked to the poor carrier status of Murini, and to increased longevity of seropositive Rattini (i.e., predominant host of Orientia), highlighting aspects that need further investigation. / AFRIKAANSE OPSOMMING: Die Rattus sensu lato kompleks, wat die belangrike biomediese model spesie Rattus norvegicus huisves, bevat ‘n groep knaagdiere wat van kliniese, landbou, en epidiomologiese belang is. Hierdie studie bevat ‘n omvattende sitogenetiese molekulêre vergelyking binne hierdie kompleks. Die kariotipes van 11 Rattus s. l. spesies en Hapalomys delacouri is ondersoek met die gebruik van konvensionele sitogenetiese tegnieke. Die data dui daarop, in kontras met vorige bevindinge, dat die bruikbaarheid van kariotipes om Asiese knaagdiere te identifiseer beperk is, aangesien min spesies-spesifieke chromosoom merkers geidentifiseer kon word. Om die gebeure wat tot die morfologie en komposisie van die huidige kariotipes gelei het, te verstaan, is nege van die 11 Rattus s. l. spesies met behulp van chromosoom fluoressente hibridisasie ondersoek. Dit het die ontdekking van ‘n rare konvergente geslagschromosoom-outosoom translokasie in H. delacouri en B. savilei tot gevolg gehad. Die vaslegging hiervan is heel moontlik bevoordeel deur die teenwoordigheid van interkalerende heterchromatien blokke (IHBs) by die grens van die translokeerde segmente. Hierdie resultate dui daarop dat Rattus s. l. deur ‘n stadige tempo van chromosoom verandering gekenmerk word, wat in skrille kontras staan met die hoë aantal chromosoom herrangskikkings wat in meeste ander murid knaagdiere geidentifiseer is. Vanuit hierdie data kon die eerste oerouer kariotipe van die Rattini bepaal word. Die gebruik van hierdie data in kombinasie met beskikbare vergelykende kaarte het dit moontlik gemaak om die vorige hipotetiese oerouer murid kariotipe te hersien. BAC-kartering het dit moontlik gemaak om sonder twyfel vas te stel dat die polimorfisme wat chromosoom pare 1, 12 en 13 in die Rattus kariotipe affekteer, die resultaat van perisentriese omsetting is. Die analise van genomiese eienskappe, soos telomere, Ag-NORs en satelliet DNA dui op ‘n beperkte patroon van chromosoom evolusie. Die bestudeerde rot satelliet DNA familie blyk takson (Rattus) spesifiek te wees met ‘n onlangse oorsprong, wat ooreenstem met die terugvoer model van satellite-evolusie. Die vergelykende aard van hierdie studie het gelei tot die verdere analise van die spesies in die Rattus s. l. kompleks in terme van hul moontlike rol as draers van “scrub typhus” deur gebruik te maak van qPCR geen uitdrukking, wat gebasseer is op “real-time” PCR. Die struktuur en transkripsie van syndecan-4, wat in die verlede aan Orientia tsutsugamushi (veroorsakende agent van scrub typhus) infeksie gekoppel is, is tussen Rattini (typhuspositief) en Murini (typhus-negatief) knaagdiere vergelyk. Ten spyte daarvan dat dit nie moontlik was om die strukturele variasie tussen Rattini en Murini met draer status te koppel nie, is daar wel ‘n skakel tussen die verlaagde uitdrukking van syndecan-4 in Murini en seropositiewe Rattini knaagdiere, in vergelyking met die wat sero-negatief was, gevind. Dit stel voor dat die verlaagde vlakke van syndecan-4 transkripsie in Murini en Rattini aan die swak draer status van Murini, asook die verhoogde langslewendheid van sero-positiewe Rattini (i.e., oorheersende gasheer van Orientia), gekoppel is. Hierdie bevindinge beklemtoon sekere belangrike aspekte vir verdere navorsing.

Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Despite more than three decades of research, and the postulation of more than 30 hypotheses of function, the adaptive significance of play remains unknown. This study quantitatively evaluated a selection of hypotheses of function, using data collected from a wild population of small, social carnivore, the meerkat, Suricata suricatta. The study found that although play in meerkats carried an energetic cost, with individuals modulating their frequency of play in response to their energy intake, none of the hypotheses evaluated by the study could identify the adaptive benefits that meerkats derived from play. Play did not increase 'social harmony' by reducing aggression between playmates, nor did it strengthen an individual's bonds to its social group, such that it remained in the group for longer, or contributed more to the group's cooperative activities. There was no evidence that meerkats used play to strengthen alliances between individuals, and young meerkats played no more frequently with their future dispersal partners than with matched controls with which they did not disperse. Play fighting experience did not improve a meerkat's subsequent fighting skills, and individuals that ultimately won the dominant breeding position within a group (through serious fighting) played no more frequently, and no more successfully, as youngsters, than the littermates that they defeated in combat. Although play was inhibited by aggression, meerkats did not use play to contest, assert or establish dominance status, and there was little evidence to suggest that the preference young meerkats showed for play partners that were well matched in age, size and ability arose from their use of play for self-assessment. This study assessed only those hypotheses of function that predicted benefits that were of importance to the inclusive fitness of the study species. For example, the enhancement of social harmony and group cohesion should be invaluable to a species whose survival is dependent upon social cooperation; and the high reproductive skew exhibited by this species places huge value upon fighting skill and the ability to win social dominance. As a consequence, this study's negative findings suggest strongly that play is not capable of providing these benefits, and that play behaviour is unlikely to be used for these purposes in any mammal species. I conclude that the most likely function of play (based on play's ubiquitous characteristics, and the findings of neurological research on rats) is the promotion of growth of the cerebral cortex. / AFRIKAANSE OPSOMMING: Ten spyte van meer as drie dekades van navorsing en die voorstelling van meer as 30 hipoteses oor funksie, bly die aanpassingswaarde van spelonbekend. Hierdie studie is 'n kwantitatiewe evaluasie van verskeie hipoteses oor funksie, en gebruik data versamel vanuit 'n wilde bevolking van 'n klein sosiale karnivoor, die meerkat, Suricata suricatta. Die studie het bevind dat hoewel spel in meerkaaie 'n energetiese koste beloop, met individue wat hul spelfrekwensie aanpas by energie-inname, geen-een van die hipoteses onder beskouing die aanpassingswaarde van spel vir meerkaaie kon verduidelik nie. Spel het nie "sosiale harmonie" bevorder deur die afuame in aggressie tussen speelmaats nie, en het ook nie 'n individu se verbintenis tot sy sosiale groep versterk sodat hy langer in die groep sou bly of meer sou bydra tot samewerkingsaktiwiteite nie. Daar was geen bewyse vir die gebruik van spel in die versterking van bondgenootskappe tussen individue nie, en jong meerkaaie het nie meer gereeld met toekomstige verspreidings-venote gespeel as met gepaarde kontroles saam met wie hulle nie uiteengegaan het nie. Speelse gevegte het nie 'n meerkat se daaropvolgende gevegsvermoëns verbeter nie, en die individue wat uiteindelik die dominante voortplantingsposisie in 'n groep gewen het (deur ernstige stryd) het nie meer gereeld ofmeer suksesvol as jongelinge gespeel in vergelyking met die werpselmaats wat hulle in die stryd oorwin het nie. Hoewel spel deur aggressie onderdruk is, het meerkaaie spel nie gebruik om dominante range te beveg, bevestig of tot stand te bring nie. Daar was min bewyse ter ondersteuning van die voorstel dat jong meerkaaie se voorkeur vir speelmaats wat hul gelyke is in ouderdom, grootte en vermoë, onstaan het in die gebruik van spel vir selfondersoek. Hierdie studie het slegs die hipoteses van funksie beskou wat voorspellings gemaak het oor die voordele wat belangrik is in die inklusiewe fiksheid van die studie-species. Byvoorbeeld, die verbetering van sosiale harmonie en groepsamehang behoort van onskatbare waarde te wees vir 'n species wat afhanklik is van sosiale samewerking vir oorlewing; en die hoë graad van voorkeuraanwas duidelik in hierdie species plaas groot waarde op gevegsvaardighede en die vermoë om sosiale dominansie te wen. Gevolglik dui hierdie ondersoek se negatiewe bevindinge daarop dat spel nie hierdie voordele kan bied nie, en dat speelgedrag heel waarskynlik nie vir hierdie doeleindes in enige soogdier-species gebruik word nie. Ek kom tot die gevolgtrekking dat die heel waarskynlikste funksie van spel (gebaseer op spel se alomteenwoordige kenmerke en die bevindinge van neurologiese navorsing op rotte) die bevordering van groei in die serebrale korteks is.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2007. / Honeybee queens typically inhibit the reproductive development of workers in the colony. However, African, Apis mellifera scutellata, honeybee queens seem to have little effect on neighbouring A. m. capensis honeybee workers as is evident in the huge losses of African honeybee colonies due to the invasion by ‘social parasitic’ Cape honeybees (pseudoclones). Certain factors; such as queen and brood presence, the level of colony defence and food availability may render host colonies more vulnerable to invasion by the Cape worker honeybees. In this study host African colonies were split to determine whether a “window of opportunity” existed for Cape honeybee infiltration and thus critical to the capensis problem. Nine African colonies were infected with native and pseudoclone Cape workers over different time periods; before, during and after splitting (treatments). I measured survival rates, as well as reproductive and pheromone development of introduced workers. The effect of brood pheromones on Cape worker reproduction was also examined. Approximately 70% of all workers were removed within 72 hours, a critical period to avoid detection by Cape workers. Queen absence significantly affected the success rate of intrusion and establishment by Cape honeybee workers (GLZ; Wald χ² = 4.49, df = 1, P = 0.033). 21% of 21-day old pseudoclones survived African queenless colonies and only 6% queenright colonies. Native Cape workers showed no difference in survival rates between African queenless (12%) and queenright (11%) colonies. Looking at introduction time, considerably more pseudoclone honeybee workers survived in treatment 1 than did native Cape honeybee workers while for treatment 3 the converse was true. These data show no obvious ‘window of opportunity’ surrounding the swarming process promoting Cape honeybee infiltration and establishment of African honeybee colonies, however the period immediately prior to colony fission represents the best opportunity for invasion by pseudoclones. As for ovary and mandibular gland secretion development, all surviving pseudoclones, irrespective of A. m. scutellata queen presence, fully developed their ovaries and concomitantly produced a mandibular gland secretion dominated by 9- oxo-2-decenoic acid (9ODA). Native Cape workers showed low levels of ovary development in queenright host colonies (8-17%) but this was not true for queenless colonies, with all but one worker developing their ovaries when introduced during and after splitting. Only 40% of native Cape workers introduced before splitting developed their ovaries suggesting that queen pheromones in the three days before splitting retarded ovary development in native Cape workers. These data strengthens the suggestion that the pseudoclone honeybee workers have advanced along the queen-worker developmental continuum. Preliminary studies on brood pheromones, an important factor regulating worker reproduction, indicated that Cape workers reproduce quicker and more eggs when exposed to African brood pheromones, compared to both A. m. capensis brood pheromones and no brood pheromones. Pheromones produced by African larvae therefore do not simply inhibit Cape worker reproductive development but accelerate the commencement of egg laying by these workers. On the whole, host African colonies, especially in the absence of their queen, appear vulnerable surrounding colony fission to invasion by both Cape honeybee worker populations even though there are low survival rates. I conclude that these two Cape honeybee worker populations do differ significantly regarding their reproductive capacity and ability in becoming social parasites.