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Grouping behaviour in the armadillo girdled lizard, Cordylus cataphractusVisagie, Louise 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Cordy/
us cataphractus and C macropholis naturally occur in groups on a year round
basis. I examined whether limited shelter availability might be responsible for this
phenomenon. Individuals were provided with an excess of shelter sites and the observed
pattern of shelter occupation was contrasted to that obtained for the solitary living species C
polyzonus. Cordy/us cataphractus consistently occupied fewer shelters than its two
congeners. Results suggest that grouping behaviour in this species is not the result of a
limitation in refuge sites. In contrast, the pattern of shelter occupation by C macropholis did
not differ significantly from that of C polyzonus, thus the aggregative behaviour observed in
the former species may partially be attributed to limited shelter availability in its natural
habitat.
Conspecific recognition by means of pheromonal detection has been reported in many
lizard families, but only for one member of Cordylidae, namely Cordy/us cordy/us. Cordylus
cataphractus individuals were exposed to ceramic tiles that had been labeled by conspecific
male and female substrate deposits. Labeling was achieved by using ceramic tiles as the
bottom half of a shelter in a lizard's home cage for ten consecutive days. Washed tiles were
used as controls. Labeled tiles did not elicit significantly more tongue-flicks than control tiles
from test specimens in a series of trials. The apparent lack of conspecific recognition via
pheromonal detection might be attributable to the group-living nature of this species, which
primarily use visual cues for identification purposes. Tongue-flicking is generally utilized in
C cataphractus in the detection of novel stimuli.
Spatial dynamics of the group-living cordylid, C cataphractus, were investigated by
studying patterns of intergroup movement. To date, literature has assumed that C
cataphractus groups represent family units, implying low or delayed dispersal rates and high
group fidelity. A mark-recapture experiment on six groups included three recaptures outside of and three recaptures within the mating season. High percentages of male, female and
juvenile lizards left their groups, but might be an artifact of microhabitat disturbance. High
proportions of males, females and juveniles entering the groups, both outside of mld within
the mating season, clearly implied a high rate of intergroup movement.
Activity and foraging patterns were studied in group-living C. cataphractus lizards by
conducting direct field observations between September 1998 and October 1999. The
influence of general weather patterns as well as the effect of group size on these patterns were
investigated by observing a small-sized, medium-sized and large group. Each group was
observed for a minimum of three sunny days per season, with scans conducted every 30
minutes between the hours of 08:00 and 20:00. There was a high rate of activity during the
mating season in spring (September). Activity declined sharply mld foraging ceased at the
onset of warm, dry conditions (February). Virtually no activity occurred just prior to the first
winter rains (July), after which the lizards emerged to forage and replenish energy stores
before onset of the next mating season. Selective inactivity might be employed to reduce
energy expenditure in this group-living lizard, where intraspecific competition is stringent.
Groups of different sizes display different thresholds at which it becomes energetically viable
for group members to emerge, as well as different patterns of spatial use around their
respective home crevices. Members of larger groups perched further from their crevices, ran
further to catch prey mld had less potential prey capture events per individual. Lizards in the
larger groups also displayed sporadic lengthy foraging excursions. Such movements might
explain the evolution of tail-biting behaviour and heavy armour, which are defensive
strategies associated with open areas. / AFRIKAANSE OPSOMMING: Cordylus
cataphractus en C. macropholis word dwarsdeur die jaar in groepe in hul
natuurlike habitat aangetref. Daar is nagevors of 'n beperking in aantal beskikbare
skuilplekke vir hierdie verskynsel verantwoordelik is. Individue is van 'n oormaat skuilings
voorsien en die waargenome patroon van skuilplekbesetting is gekontrasteer met dié verkry
vir '11 enkelwonende species, naamlik C. polyzonus. Cordylus cataphractus het voortdurend
minder skuilplekke beset as sy kongeneriese species. Groepsgedrag in C. cataphractus is dus
nie die resultaat van 'n tekort aan beskikbare skuilplekke nie. In teenstelling hiermee het die
patroon van skuilplekbesetting vertoon deur C. macropholis nie noemenswaardig verskil van
dié van C polyzonus nie. Dus mag die groepsgedrag wat gewoonlik in C. macropholis
waargeneem word 'n uitvloeisel wees van 'n beperking op die beskikbaarheid van skuilplekke
in sy natuurlike habitat.
Herkenning van speciesgenote deur waarneming van ferornone is vir verskeie
akkedisfamilies gerapporteer, maar slegs vir een lid van Cordylidae, naamlik C. cordylus.
Cordylus cataphractus individue is blootgestel aan keramiekteëls wat gemerk is met
substraat-neerleggings van manlike en vroulike speciesgenote. Sodanige merking is uitgevoer
deur die keramiekteëls vir tien dae lank te gebruik as die onderste helfte van akkedisse se
skuilplekke in hul tuishokke. Gewaste teëls is as kontroles gebruile Gemerkte teëls het nie
statisties beduidend meer tongskiete van die akkedisse uitgelok as kontrole teëls in 'n reeks
toetse nie. Die klaarblyklike afwesigheid van speciesgenootherkenning deur middel van
feromoon waameming kan moontlik toegeskryf word aan die groeplewende gedrag van C.
cataphractus, wat primêr visuele informasie vir identifikasie gebruik. Cordylus cataphractus
gebruik tongskiete oor die algemeen vir die waarneming vannuwe omgewingsstimuli.
Die ruimtelike dinamika van 'n groeplewende gordelakkedis, C. cataphractus, is
ondersoek deur die patroon van intergroepbeweging na te vors en groepsgetrouheid te meet. Tot op datum is daar in die literatuur aanvaar dat C cataphractus groepe familie-eenhede
verteenwoordig, wat lae of vertraagde verpreidingstempo' sasook' n hoë mate van
groepsgetrouheid impliseer. 'n Merk-hervang eksperiment is op ses groepe uitgevoer,
insluitend drie hervang episodes buite en drie binne die paarseisoen. 'n Hoë persentasie
manlike, vroulike en onvolwasse akkedisse het hul groepe verlaat, maar dit mag bloot 'n
uitvloeisel van versteuring van die mikrohabitat wees. 'n Hoë proporsie mannetjies, wyfies
en onvolwassenes het egter by die groepe aangesluit, beide buite en binne die paarseisoen,
wat onteenseglik op 'n hoë mate van intergroep beweging dui. Daar kom derhalwe veel vryer
bewegingspatrone in hierdie species voor as voorheen vermoed en dit is hoogs onwaarskynlik
dat groepe familie-eenhede verteenwoordig.
Aktiwiteits- en voedingspatrone van die groeplewende akkedis, C cataphractus, is
bestudeer in 'n reeks veldobservasies tussen September 1998 en Oktober 1999. Afgesien van
die invloed van algemene weerspatrone. is die effek van groepgrootte op hierdie patrone
ondersoek deur 'n klein, medium en groot groep te observeer. Elke groep is waargeneem oor
. 'n minimum periode van drie dae per seisoen met opnames elke 30 minute, tussen 08:00 ten
20:00. 'n Hoë aktiwiteitsvlak is gedurende lente tydens die paarseisoen gehandhaaf
(September). Met die aanvang van warm en droë kondisies (Februarie) het aktiwiteitsvlakke
skerp begin daal en voedingsgedrag is gestaak. Feitlik geen aktiwiteit was waarneembaar kort
voor die eerste winterreëns (Julie) nie, waamá akkedisse intensiefbegin voed het om
energiestore op te bou voor die aanvang van paartyd. Selektiewe onaktiwiteit verminder
moontlik energieverbruik in hierdie groeplewende akkedis, waar intraspesifieke kompetisie
streng is. Verskillende groepgroottes beskik oor verskillende perke waar dit vir die individu
energeties voordelig sou wees om uit die skeur te kom, asook 'n variasie in ruimtelike gebruik
om die skeur. Individue van die twee groter groepe het nader aan hul rotsskeur gesit, het verder van
die skeur af prooi vang en het beduidend minder potensiële voedingskanse gehad. Akkedisse
in die groter groepe het voorts sporadiese lang voedingsekskursies getoon. Hierdie
bewegings mag die evolusie van stertbytgedrag en 'n swaar pantser, verdedigingstrategieë wat
met oop areas geassosieer word, verduidelik.
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Geographical variation in the number of generation glands in cordylid lizardsDu Toit, Dahne A. (Dahne Anne) 03 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Geographic variation in the presence/absence of generation glands in females of the
cordylus-niger-oelofseni complex was described and correlated with climatic variables.
Preserved and live specimens from 96 localities in the area south of 32°30' S and west of
19°45' E in the Western Cape, South Africa, were examined for the presence or absence of
generation glands. Females from western coastal localities and from the Cape Fold
Mountains generally lack generation glands, while females from inland lowland localities
generally possess glands. A GIS analysis was performed to determine mean annual
minimum temperature, mean annual maximum temperature, potential evaporation, mean
annual precipitation, mean annual fog and mean annual cloud cover measured at 14:00 for
each locality. Discriminant function and canonical analyses showed a highly significant
correlation between the presence and absence of generation glands and five of the six
climatic variables. It is suggested that the high incidence of fog and lower temperatures
experienced along the west coast as a result of the cold Benguela Current, and the high
incidence of orographic fog and cloud cover in the Cape Fold Mountains may affect energy
allocation in females. In order to maintain their reproductive output, females may be
forced to invest less energy in secondary sexual characters such as generation glands.
Interspecific variation in the location, occurrence, number, and age of gland
differentiation was investigated for cordylid lizards. For several species, data were
obtained from the literature and for others data were obtained from material housed in the
Ellerman Collection of the University of Stellenbosch. Cordylus cordylus and C.
cataphractus were used for an evaluation of inter- and intrapopulation variation. Data for
C. cordylus were obtained from five populations on the coastal lowlands of the Western
Cape, while data on C. cataphractus come from the literature. The sex, snout-vent length, and number of generation glands were recorded for a representative sample of lizards at
each locality. While in all species generation glands were located in the femoral region,
Cordylus giganteus and C. microlepidotus had additional generation glands elsewhere on
the body. It is suggested that additional generation glands in these species may be related
to an increased need for chemical communication in a low-visibility environment in the
case of C. giganteus, and in low population densities in the case of C. microlepidotus.
Generation glands are present in all cordylid males, but females of some species may lack
these glands. All cordylids display sexual dimorphism with regards to the presence and
number of generation glands, with males having significantly more glands than females,
indicating that these glands may play a more important role in males than in females. Low
sexual dimorphism in at least two species suggests that generation glands may be equally
important in both sexes of these species. In females, the presence of generation glands is
closely regulated by climate. There is no indication of differences in generation gland
profile between ground-dwelling and rock-dwelling species, except that in at least three
ground-dwelling species, generation glands are already present at birth. In other species
these glands differentiate only later in life. In the males of most species, generation glands
start to differentiate prior to or at sexual maturity with a drastic increase in number when
asymptotic body size is reached. The considerable inter- and intrapopulation variation in
gland number in females, but not in males, underscores the hypothesis that the presence of
generation glands in females is energy-linked and closely regulated by climate. An
opposite geographic pattern of generation gland number in C. cataphractus, suggests that
other factors than climate must be responsible for a difference in gland number and a
difference in population density is suggested as explanation.
To test for differences in aggression levels, females with and those without generation
glands were staged in two experiments. In one experiment, females from different localities were staged against each other, while females from the same locality were paired
in another experiment. No significant difference in aggression levels between females
with and those without generation glands were observed in both experiments. It is
suggested that generation glands do not exclusively function in territorial marking, but
rather as a scent enhancer for femoral gland secretions.
Inorder to elucidate the functional significance of generation glands, male response to
female gland stimuli was investigated for 12 male C. cordylus. Males were presented with
different female gland secretions (femoral, generation, and femoral and generation gland
secretion combined) and water was used as a control. Total number of tongue-flicks and
number of tongue-flicks directed at the secretion were counted. No significant difference
was observed in the number of tongue-flicks between the different treatment groups.
Males did, however, display leg-waving and head-rubbing behaviour. At present, the
behaviour displayed by male C. cordylus in the presence of female gland stimuli, is
unclear. The general absence of tongue-flicking of sandpaper labelled by female gland
stimuli may be because of a flaw in the experimental design or because the experiment was
conducted outside the breeding season. The display ofleg-waving and head-rubbing
behaviour, however, suggests that cordylids do not exclusively rely on tongue-flicking for
detection of conspecifics. The real function of generation glands thus still remains
unresolved and further studies are needed to clarify this. / AFRIKAANSE OPSOMMING: Geografiese variasie in die aan-/afwesigheid van generasiekliere in wyfies van die
cordylus-niger-oelofseni kompleks is beskryf en met klimaatsveranderlikes gekorreleer.
Gepreserveerde en lewende materiaal, afkomstig van 96 lokaliteite in die area suid van
32°30' S en wes van 19°45'0 in die Wes-Kaap, Suid-Afrika, is vir die aan- ofafwesigheid
van generasiekliere ondersoek. Generasiekliere is oor die algemeen afwesig in wyfies van
westelike kuslokaliteite en die Kaapse Plooiberge, terwyl dit aanwesig is in wyfies van die
binnelandse laagland lokaliteite. 'n GIS-analise is gedoen om die gemiddelde jaarlikse
minimum temperatuur, gemiddelde jaarlikse maksimum temperatuur, potensiële
verdamping, gemiddelde jaarlikse neerslag, gemiddelde jaarlikse mis en gemiddelde
jaarlikse wolkbedekking, gemeet teen 14:00, vir elke lokaliteit te bepaal. Diskriminantefunksie
en kanonieke analises toon 'n hoogs beduidende korrelasie tussen die aan- en
afwesigheid van kliere en vyf van die ses klimaatsveranderlikes. Daar word voorgestel dat
die hoë voorkoms van mis en lae temperature wat langs die weskus ervaar word as gevolg
van die koue Benguela Seestroom, en die hoë voorkoms van orografiese mis en
wolkbedekking in die Kaapse Plooiberge, die energie-toekenning in wyfies beïnvloed. Om
hulle voortplantingsuitset te handhaaf, word wyfies moontlik gedwing om minder energie
in sekondêre geslagskenmerke, soos generasiekliere, te belê.
Interspesifieke variasie in die posisie, voorkoms, aantal en tyd van klierontwikkeling is
vir verskeie gordelakkedisspesies ondersoek. Data vir verskeie spesies is vanuit die
literatuur verkry, terwyl data vir ander spesies vanafmaterial in die Ellerman-versameling
van die Universiteit van Stellenbosch verkry is. Cordylus cordylus en C. cataphractus is
vir 'n evaluering van inter- en intrapopulasie variasie gebruik. Data vir C. cordylus is
vanafvyfpopulasie wat op die kuslaaglande van die Wes-Kaap voorkom, ingesamel, terwyl data oor C. cataphractus vanuit die literatuur verkry is. Geslag, snoet-kloaak-lengte
en die aantal generasiekliere is aangeteken vir 'n verteenwoordigende aantal individue van
elke populasie. Terwyl generasiekliere in die femorale wyk van alle spesies aangetref
word, het Cordylus giganteus en C. microlepidotus ook addisionele generasiekliere in
ander dele van die liggaam. Daar is tot die gevolgtrekking gekom dat addisionele
generasiekliere in hierdie spesies moontlik verwant is aan 'n groter behoefte aan chemiese
kommunikasie in 'n lae sigbaarheidsomgewing in die geval van C. giganteus, en in 'n lae
populasiedigtheid in die geval van C. microlepidotus. Generasiekliere word in alle
gordelakkedis mannetjies aangetref, maar kan afwesig wees in wyfies van sommige
spesies. Alle gordelakkedisse toon geslagsdimorfisme met betrekking tot die aanwesigheid
en aantal generasiekliere, en mannetjies het beduidend meer kliere as wyfies, wat daarop
dui dat hierdie kliere moontlik 'n meer belangrike rol by mannetjies as by wyfies speel.
Lae geslagsdimorfisme inten minste twee spesies stel voor dat generasiekliere moontlik
ewe belangrik in beide geslagte van hierdie spesies kan wees. In wyfies word die
aanwesigheid van generasiekliere sterk deur klimaat gereguleer. Daar is geen aanduiding
van verskille in generasieklierprofiel tussen grondbewonende en rotsbewonende spesies
nie, behalwe dat generasiekliere reeds by geboorte teenwoordig is in ten minste drie
grondbewonende spesies. In ander spesies ontwikkel hierdie kliere eers later. In
mannetjies van die meeste spesies, begin generasiekliere voor oftydens geslagsrypheid
ontwikkel, met 'n drastiese toename in aantal kliere wanneer asimptotiese liggaamsgrootte
bereik word. Die aansienlike inter- en intrapopulasie variasie in aantal kliere in wyfies,
maar nie in mannetjies nie, ondersteun die hipotese dat die teenwoordigheid van
generasiekliere in wyfies aan energie gekoppel is en deur klimaat gereguleer word. 'n
Teenoorgestelde geografiese patroon in die aantal generasiekliere in C. cataphractus, stel voor dat ander faktore as klimaat vir die verskil in aantal kliere verantwoordelik is en 'n
verskil in populasiedigtheid word as verklaring voorgestel.
Om vir verskille in aggressievlakke te toets, is wyfies met en wyfies sonder
generasiekliere is teenoor mekaar getoets in twee eksperimente. In een eksperiment is
wyfies van verskillende lokaliteite teenoor mekaar getoets, en in 'n ander eksperiment is
wyfies van dieselfde lokaliteit teenoor mekaar getoets. Inbeide eksperimente is geen
beduidende verskille is in die aggressievlakke van wyfies nie waargeneem nie. Daar word
voorgestel dat generasiekliere nie uitsluitlik in gebiedsafbakening funksioneer nie, maar
dat dit eerder as reukversterker vir die femorale kliere dien.
Om die funksie van generasiekliere vas te stel, is die reaksie van 12 mannetjie C.
cordylus op klierstimuli van wyfies getoets. Verskillende kliersekresies (femoraal,
generasie, en femoraal en generasie gekombineerd) van wyfies is mannetjies voorgelê, en
water is as 'n kontrole gebruik. Totale aantal tongskiete en aantal tongskiete wat na die
sekresie gerig is, is getel. Geen beduidende verskil in die aantal tongskiete is tussen die
verskillende groepe waargeneem nie. Mannetjies het egter beenwaai- en kopvryfgedrag
getoon. Die rede vir die gedrag wat deur C. cordylus mannetjies in die teenwoordigheid
van klierstimuli van wyfies vertoon word, is egter tans onduidelik. Die algemene
afwesigheid van tongskiete na skuurpapier wat met klierstimuli van wyfies gemerk is, mag
moontlik wees as gevolg van 'n fout in die eksperimentele ontwerp of omdat die
eksperiment buite die paarseisoen uitgevoer is. Die vertoning van beenwaai- en
kopvryfgedrag stel egter voor dat gordelakkedisse nie uitsluitlik op tongskiete staatmaak
om lede van dieselfde spesie waar te neem nie. Die ware funksie van generasiekliere is
dus steeds onopgelos en verdere studies word benodig om dit duidelikheid hieroor te kry.
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An analysis of the Pseudocordylus melanotus complex (Sauria: Cordylidae)Bates, Michael Francis 04 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The taxonomic status of southern Africa’s rupicolous crag lizards (genus Pseudocordylus) was
investigated. As considerable confusion exists in the literature regarding the type specimens and
type localities of the various taxa, resolution of these problems were considered the starting point
of the study. Examination of museum specimens allowed for the designation of lectotypes,
alloparalectotypes and/or paralectotypes. Of particular relevance to this study was the rediscovery
of Andrew Smith’s type specimens of P. m. melanotus and P. m. subviridis. Restriction
of the type locality of P. m. subviridis, based on entries in Smith’s diary and journal, allowed for
the confirmation of previous interpretations and definitions of the two taxa. The geographical
distribution of the various taxa and populations was determined using an extensive locality
database.
Two kinds of molecular markers, namely allozymes and mitochondrial DNA, were used in an
attempt to resolve taxon boundaries within the P. melanotus species complex. The allozyme
analysis indicated that P. m. melanotus might be polyphyletic and comprised of two unrelated
lineages. Furthermore, fixed allelic differences between parapatric populations of P. m.
melanotus and P. m. subviridis, and between sympatric populations of P. m. subviridis and P.
langi, suggested that all three forms might be considered full species, with the possibility of more
cryptic species present in the complex. Pseudocordylus transvaalensis differed from most other
populations by 1-3 fixed allelic differences, but was indistinguishable from the Nkandhla district
(central KwaZulu-Natal) population of P. m. melanotus. There were no heterozygous individuals
in a sample from Monontsha Pass (Qwa-Qwa), a population reportedly comprising P. m.
melanotus and P. m. subviridis, as well as intermediates, and all specimens were assignable to P.
m. subviridis. The allozyme study was, however, based on phenetic principles and for further
taxonomic resolution a cladistic approach was required. An mtDNA analysis (16S rRNA gene)
using Maximum Parsimony, Maximum Likelihood and Bayesian analyses was therefore
conducted to determine phylogenetic relationships among species and subspecies and to re-assess
the taxonomic status of forms in the P. melanotus species complex. The mtDNA analysis
corroborated most of the results obtained in the allozyme analysis. Firstly, P. langi was again
found to be basal. With the addition of P. microlepidotus and P. spinosus to the ingroup, it is now
apparent that P. langi is the basal species in the genus. (Recent studies have indicated that P.
capensis and P. nebulosus are not congeneric with Pseudocordylus.) Secondly, the 16S rRNA
results confirm that P. m. melanotus, as presently construed, is comprised of two clades that are
not sister groups. The northern populations of P. m. melanotus (Sabie and Lochiel) form a fairly
deeply divergent clade that may represent a separate species. The Nkandla population was, however, found to cluster with the other southern P. m. melanotus populations and not with P.
transvaalensis as was the case in the allozyme electrophoretic analysis. However, the most
surprising result of the 16S rRNA analysis was the finding that both P. microlepidotus and P.
spinosus are embedded within P. m. subviridis. This suggests that these two species evolved from
within P. m. subviridis and may have been separated only recently, with rapid morphological
divergence occurring, but with limited genetic differentiation. It is suggested that all of the above
three taxa be provisionally treated as full species.
There was also morphological support for the uniqueness of all groupings indicated by the
mtDNA analysis. Pseudocordylus transvaalensis is characterized by its large size, unique dorsal
and gular (black) colour patterns, as many as three horizontal rows of lateral temporal scales, a
series of small scales posterior to the interparietal scale, and usually two subocular scales behind
the median subocular on either side of the head. The various populations currently classified
under the name P. melanotus are more difficult to separate, but P. m. melanotus and P. m.
subviridis usually differ as follows: frontonasal divided in P. m. melanotus, undivided in P. m.
subviridis (and most Northern melanotus); lateral temporals in two rows, upper more elongate
versus single row of much elongated scales; longitudinal rows of dorsolaterals closely-set versus
widely separated; femoral pores of females pit-like versus deep with secretory plug. Northern
melanotus differs from Southern melanotus in usually having an undivided frontonasal scale and
seldom having a small scale present behind the frontonasal. Pseudocordylus langi has unique
dorsal and gular colour patterns (including a series of blue spots on the flanks), granular dorsals
with 6-9 paravertebral rows of enlarged flat scales, high total numbers of femoral pores (25-34)
and usually only five (smooth not keeled or ridged) infralabial scales on either side of the head.
Pseudocordylus spinosus also has unique dorsal and gular colour patterns, spinose lateral scales,
frontonasal longer than wide and excluded from the loreal scales, low total femoral pore counts
(6-9), and females (not only males) have differentiated femoral scales. Both Principal
Components Analysis (PCA) and Canonical Discriminant Analysis (CDA) distinguished four
groups, namely P. transvaalensis, P. langi, P. spinosus and a P.
melanotus/subviridis/microlepidotus cluster. A separate CDA of all P. melanotus populations
partly distinguished between Southern melanotus and P. m. subviridis, and largely separated
Northern melanotus; whereas a CDA of P. transvaalensis showed that all three allopatric
populations are 100% distinguishable in morphological space.
A Nested Clade Analysis indicated that fragmentation as well as range expansion played a role in
the distribution of the P. melanotus species complex. This may be explained by climatic
oscillations (high-low temperatures and wet-dry cycles) during the Cenozoic that caused habitat
expansion and contraction. Based on the topology of the mtDNA phylogram it is apparent that the genus Pseudocordylus originated along the eastern escarpment. A P. langi-like ancestor may
have had an extensive range along the eastern escarpment, with the Maloti-Drakensberg forming
the southern limit of its range. During a subsequent rise in global temperatures, range contraction
and fragmentation took place, leaving an isolated population in the south and one in the north.
The southern population survived unchanged in the Maloti-Drakensberg refugium, but the
northern population was forced to adapt to the warmer conditions. Thereafter, the northern form
expanded its range again, but during a subsequent cooler period, range contraction occurred,
resulting in an isolated north-eastern population in the Sabie-Lochiel area in Mpumulanga
(Northern melanotus) and a western population. Relationships in the latter clade are not
sufficiently resolved to allow further reconstruction of biogeographic history, but it is clear that a
P. m. subviridis-like form became isolated in the south where it eventually came into contact with
P. langi at high elevations. Pseudocordylus m. subviridis eventually extended its range southwestwards
into the inland mountains of the Eastern Cape and Cape Fold Mountains to give rise to
the P. microlepidotus complex. This cycle of range expansion and contraction may also account
for the isolated populations at Suikerbosrand, Nkandhla district, and in the Amatole-Great
Winterberg mountain region. Furthermore, it is suggested that P. spinosus originated from a P. m.
subviridis-like ancestral population that became isolated on the lower slopes of the Drakensberg
where terrestrial predation pressure resulted in a quick shift in morphology from fairly smooth
body scales to a more spiny morphology. / AFRIKAANSE OPSOMMING: Die taksonomiese status van suidelike Afrika se rotsbewonende krans-akkedisse (genus
Pseudocordylus) is ondersoek. Omdat daar aansienlike verwarring in die literatuur bestaan met
betrekking tot die tipe monsters en die tipe lokaliteite van die verskillende taksa, is die oplossing
van hierdie probleme as die beginpunt van hierdie studie geneem. Die bestudering van akkedismonsters
in museums het dit moontlik gemaak om lektotipes, alloparalektotipes en/of
paralektotipes aan te wys. Van besondere belang vir hierdie studie is die herontdekking van
Andrew Smith se tipe monsters van P. m. melanotus en P. m. subviridis. Die beperking van die
tipe lokaliteit van P. m. subviridis, gebaseer op inskrywings in Smith se dagboek en joernaal, het
dit moontlik gemaak om vorige interpretasies en definisies van die twee taksa te bevestig. Die
geografiese verspreiding van die verskillende taksa en bevolkings is bepaal deur middel van ’n
omvattende lokaliteit databasis.
Twee soorte molekulêre merkers, naamlik allosieme en mitokondriale DNS, is gebruik in ʼn
poging om uitsluitsel te verkry oor die takson-grense binne die P. melanotus-spesiekompleks.
Die allosiem-analise het daarop gedui dat P. m. melanotus moontlik polifileties mag wees en uit
twee onverwante stamboom-vertakkings kan bestaan. Verder het vaste alleliese verskille tussen
parapatriese bevolkings van P. m. melanotus en P. m. subviridis, en tussen simpatriese bevolkings
van P. m. subviridis en P. langi, daarop gedui dat al drie vorme as volledige spesies beskou kan
word, met die moontlikheid dat meer kriptiese spesies in die kompleks teenwoordig kan wees.
Pseudocordylus transvaalensis het van die meeste ander bevolkings verskil met 1-3 vaste alleliese
verskille, maar was ononderskeibaar van die bevolking van P. m. melanotus van die Nkandhla
distrik (sentraal KwaZulu-Natal). Daar was slegs homosigote individue in ʼn steekproef van
Monontsha Pas (Qwa-Qwa), ʼn bevolking wat volgens die literatuur P. m. melanotus en P. m.
subviridis, sowel as intermediêre omvat, en alle monsters was toekenbaar aan P. m. subviridis.
Die allosiemstudie is egter gebaseer op fenetiese beginsels en vir verdere taksonomiese oplossing
is ʼn kladistiese benadering vereis. ʼn Mitokondriale DNS-analise (16S rRNS geen) wat gebruik
maak van Maksimum Parsimonie-, Maksimum Waarskynlikheids- en Bayes-analises is daarom
uitgevoer om die filogenetiese verwantskappe tussen spesies en subspesies te bepaal en om die
taksonomiese status van vorme in die P. melanotus-spesiekompleks te herondersoek. Die
mtDNS-analise het die meeste van die resultate van die allosiem-analise bevestig. Eerstens, P.
langi is weer bevind om basaal te wees. Met die byvoeging van P. microlepidotus en P. spinosus
tot die binne-groep het dit nou duidelik geword dat P. langi die basale spesie in die genus is.
(Onlangse studies het aangedui dat P. capensis en P. nebulosus nie kongeneries met
Pseudocordylus is nie.) Tweedens, die 16S rRNS resultate bevestig dat P. m. melanotus, soos tans vasgestel, saamgestel is uit twee klade wat nie sustergroepe is nie. Die noordelike
bevolkings van P. m. melanotus (Sabie en Lochiel) vorm ʼn redelik diep divergente klaad wat ʼn
afsonderlike spesie mag verteenwoordig. Dit is egter bevind dat die Nkandla bevolking
saamgegroepeer het met die ander suidelike P. m. melanotus-bevolkings en nie met P.
transvaalensis soos wat die geval was in die allosiem-elektroforetiese analise nie. Die mees
verbasende resultaat van die 16S rRNS-analise was egter die bevinding dat beide P.
microlepidotus en P. spinosus genestel was binne P. m. subviridis. Dit dui daarop dat hierdie
twee spesies kon ontwikkel het vanuit P. m. subviridis en slegs onlangs van mekaar geskei het,
toe vinnige morfologiese splitsing voorgekom het, maar met beperkte genetiese differensiasie.
Dit word voorgestel dat al drie die bogenoemde taksa voorlopig as volledige spesies beskou word.
Daar was ook morfologiese steun vir die uniekheid van al die groeperings wat die mtDNS-analise
uitgewys het. Pseudocordylus transvaalensis kan uitgeken word aan sy bogemiddelde grootte,
unieke dorsale en (swart) kleurpatrone op die keel, so veel as drie horisontale rye lateraaltemporale
skubbe, ʼn reeks klein skubbe agter die interpariëtale skub, en gewoonlik twee
subokulêre skubbe agter die middelste subokulêre skub op beide kante van die kop. Die
verskillende bevolkings wat tans geklassifiseer word as P. melanotus is moeiliker om van mekaar
te skei, maar P. m. melanotus en P. m. subviridis verskil gewoonlik soos volg: frontonasale skub
in twee gedeel in P. m. melanotus, heel in P. m. subviridis (en in die meeste Noordelike
melanotus); lateraal-temporale skubbe in twee rye, die boonste ry met verlengde skubbe teenoor ʼn
enkele ry verlengde skubbe; longitudinale rye van dorsolaterale skubbe naby aan mekaar teenoor
ver uit mekaar; femorale porieë van wyfies klein en vlak teenoor diep met sekreterende proppe.
Noordelike melanotus verskil van Suidelike melanotus deurdat hulle gewoonlik ʼn heel
frontonasale skub het en daar selde ʼn klein skub teenwoordig is agter die frontonasale skub.
Pseudocordylus langi het unieke dorsale en keel-kleurpatrone (wat ʼn reeks blou kolle op die sye
insluit), granulêre dorsale skubbe met 6-9 rye vergrote plat skubbe langs die rugsteen, ʼn groot
totale aantal femorale porieë (25-34), en gewoonlik net vyf (glad, ongerif) infralabiale skubbe op
elke kant van die kop. Pseudocordylus spinosus het ook unieke dorsale en keel-kleurpatrone,
skerp laterale skubbe, frontonasale skub langer as wyd en nie in kontak met die loreale skubbe
nie, klein totale aantal femorale porieë (6-9), en wyfies (nie net mannetjies nie) het
gedifferensieerde femorale skubbe. Die Hoof-komponent Analise (HKA) en die Kanonieke
Diskriminant Analise (KDA) het albei vier groepe geïdentifiseer, naamlik P. transvaalensis, P.
langi, P. spinosus en ʼn P. melanotus/subviridis/microlepidotus groepering. ʼn Aparte KDA van
alle P. melanotus bevolkings het gedeeltelik onderskei tussen Suidelike melanotus en P. m.
subviridis, en die Noordelike melanotus is grootliks van die ander onderskei; terwyl ʼn KDA van
P. transvaalensis daarop gedui het dat al drie allopatriese bevolkings 100% onderskeibaar in
morfologiese ruimte is. ʼn Genestelde Klaad-Analise het aangedui dat fragmentasie, sowel as gebiedsuitbreiding, ʼn rol
gespeel het in die verspreiding van die P. melanotus-spesiekompleks. Dit kan moontlik verklaar
word deur die klimaatswisselinge (hoë-lae temperature en nat-droë siklusse) gedurende die
Senosoikum wat habitat-uitbreiding en –verkleining veroorsaak het. Gebaseer op die topologie
van die mtDNS filogram is dit duidelik dat die genus Pseudocordylus al langs die oostelike
platorand ontstaan het. ʼn Voorouer soortgelyk aan P. langi kon ʼn uitgebreide gebied al langs die
oostelike platorand gehad het, met die Maloti-Drakensberg wat die suidelike limiet van hierdie
gebied gevorm het. Gedurende ʼn daaropvolgende toename in globale temperature het
gebiedsverkleining en fragmentasie plaasgevind, wat ʼn geïsoleerde bevolking in die suide en een
in die noorde tot gevolg gehad het. Die suidelike bevolking het onveranderd oorleef in die
Maloti-Drakensberg skuilplek (“refugium”), maar die noordelike bevolking is geforseer om aan te
pas in die warmer toestande. Daarna het die noordelike vorm se gebied weer uitgebrei, maar
gedurende ʼn daaropvolgende koeler periode het gebiedsverkleining weer plaasgevind, met die
gevolg dat daar ʼn geïsoleerde noord-oostelike bevolking in die Sabie-Lochiel-area in
Mpumalanga (Noordelike melanotus) en ʼn bevolking in die weste was. Verwantskappe in die
laasgenoemde klaad is nie voldoende opgelos om verdere rekonstruksie van die biogeografiese
geskiedenis moontlik te maak nie, maar dit is duidelik dat ʼn vorm soortgelyk aan P. m. subviridis
geïsoleer geraak het in die suide waar dit eindelik op hoë liggings in kontak gekom het met P.
langi. Die gebied van P. m. subviridis is ook later suidweswaarts uitgebrei tot in die binnelandse
berge van die Oos-Kaap en Kaapse Plooiberge om tot die ontstaan van die P. microlepidotuskompleks
aanleiding te gee. Hierdie siklus van gebiedsuitbreiding en verkleining kan ook ʼn
verklaring bied vir die geïsoleerde bevolkings by Suikerbosrand, Nkandhla distrik, en in die
Amatole-Groot Winterberg-streek. Verder word voorgestel dat P. spinosus ontstaan het uit ʼn
voorouerlike bevolking soortgelyk aan P. m. subviridis wat geïsoleerd geraak het op die laer
hange van die Drakensberg waar die druk van aardsbewonende roofdiere tot ʼn vinnige
verandering in morfologie vanaf redelik gladde liggaamskubbe tot ʼn meer skerppuntige
morfologie gelei het.
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Histological description of generation glands and their functional relationship to the shedding cycle in cordylid lizardsSearby, Charles Alexander 03 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Specialized skin scales (generation glands) and undifferentiated skin scales were
compared in three species of cordylid lizard, viz. Cordy/us cordy/us, Pseudocordy/us
micro/epidotus and P. capensis. These skin derivatives were histologically examined
and compared, using data existing in literature (Maderson, 1966; 1967; 1968a) with
similar structures in gekkonids. Histological descriptions of cordylid skin structure
were the same as those shown for gekkonids. Three types of generation glands
were identified in cordylids (Van Wyk & Mouton, 1992), and these proved to be
different to those existing in gekkonid species. These three types of generation
glands were further compared regarding their ecdysis histology, which proved to be
identical, thus, these glands differ only on gross morphological structure. Skin of all
three species was also compared with regard to ecdysis, and while the histology of
all three was identical, shedding activity was shown to differ in all three species. P.
micro/epidotus displayed dormancy in the germinative layer for much longer periods
of the year than either of the other two species, while P. capensis displayed very little
dormancy. C. cordy/us displayed an intermediate pattern of ecdysis activity and
dormancy. Autoradiography was performed on all species in both ecdysis activity
and dormancy periods, to compare mitotic activity patterns in these periods.
Generation gland activity appeared to correlate well with known testosterone peaks
in the testicular cycle in all three species. Asynchrony between generation glands
and skin scales was shown in all three species. / AFRIKAANSE OPSOMMING: GENERASIEKLIERE EN VERVELLINGSIKLUSSE IN GORDELAKKEDISSE
(SAURIA: CORDYLIDAE)
Drie spesies gordelakkedisse, Gordy/us cordy/us, Pseudocordy/us micro/epidofus en
P. capensis, se gespesialiseerde velskubbe (generasiekliere) en gewone velskubbe
word vergelyk. Hierdie velskubbe word deur histologiese metodes geëksamineer en
vergelyk, met gebruik van data wat reeds in die literatuur bestaan (Maderson, 1966;
1967; 1968a), met soortgelyke strukture in Gekkonidae. Histologiese beskrywing
van Cordylidae veistruktuur was identies met dié van Gekkonidae. Drie tipes
generasiekliere was geïdentifiseer in gordelakkedisse (van Wyk & Mouton, 1992), en
hulle verskil gedeeltlik van naverwante strukture in Gekkonidae. Hierdie drie tipes
generasiekliere was verder vergelyk met betrekking tot hulle vervellingsiklus
histologie, wat identies was. Dus verskil hulle net met betrekking tot hulle vorm. Vel
is ook vergelyk met dieselfde metodes. Alhoewel daar geen verskille was met
betrekking tot hulle histology nie, was die tye van aktiwiteit van kiem-sellae
beduidend verskillend in alle spesies. In P. micro/epidofus het die kiem-sellaag
russtadium baie langer geduur as in die ander twee spesies, terwyl P. cepensis
amper geen russtadium getoon het nie. G. cordy/us het 'n intermediêre
gedragspatroon vertoon tussen aktiewe en rustende fase met betrekking tot sy
vervellingsiklus. Outoradiografie is gebruik op elke spesie, in beide aktiewe en
rustende vervellingsfases, om verskille in mitotiese aktiwiteit te wys. Generasieklier
aktiwiteit blyk te korreleer met pieke van testosteroonvlakke van die testikulêre siklus
in al drie spesies. Asinkronie is aangetoon tussen generasiekliere en velskubbe in al
drie spesies.
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Chemiese kommunikasie van die Suid-Afrikaanse gordelakkedisseLouw, Stefan 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The sungazer, Cordylus giganteus, is an endangered lizard species belonging to the
family Cordylidae. It has been speculated that the function of semiochemical
communication is performed by two types of skin glands, the femoral glands and the
generation glands, which are also found in this family of lizards. Other skin glands
and also the cloacal glands are further possible sources of semiochemicals. The
investigation of these potential sources of chemical messages in C. giganteus, served
as a starting point towards a better understanding of the chemical communication of
lizard species belonging to the family Cordylidae. In continuation of this study the
femoral gland secretion of the Cape girdled lizard, C. cordylus, was also investigated.
Gas chromatography, low resolution GC-MS, GC-HR-MS, MO-TMS derivatisation
and retention time comparison were used as analytical techniques in the chemical
characterization of the femoral and generation gland secretions of C. giganteus and
the femoral gland secretion of C. cordylus. Some compounds were not identified
because of their low concentration in the secretions and/or mass spectra could not be
obtained for pure compounds because of co-elution with other compounds.
Compounds identified in the femoral gland secretion include the following:
Carboxylic acids - saturated and unsaturated
Alcohols
Ketones
Aldehydes - saturated and unsaturated
Esters - saturated and unsaturated
Hydrocarbons - saturated and unsaturated
Nitriles
Amides - saturated and unsaturated
y-Lactones
Squalene
u-Tocopherol
Steroids Quantitative analysis of the femoral and generation gland secretions of a number of
sungazers indicated distinct differences between the secretions of males and females
(in the case of the femoral gland secretions), but no apparent trend could be found in
the differences between the femoral and generation gland secretions of individual
lizards of the same gender. Qualitative seasonal differences were however observed in
the femoral gland secretions of all individuals of C giganteus. / AFRIKAANSE OPSOMMING: Die ouvolk, Cordylus giganteus, is 'n bedreigde akkedisspesie van die familie
Cordilidae. Daar is gespekuleer dat twee soorte velkliere wat by hierdie familie
akkedisse voorkom, naamlik die femorale- en generasiekliere, betrokke is by
semiochemiese kommunikasie van hierdie diere. Ander velkliere, asook die kliere in
die akkedisse se kloaka, is ook potensiele bronne van semiochemiese verbindings. Die
bestudering van hierdie potensiele bronne van chemiese boodskappe by C. giganteus
is as 'n beginpunt gebruik om die semiochemiese kommunikasie van die akkedisse
van die familie Cordilidae beter te verstaan. Ter uitbreiding van hierdie studie is die
femorale klierafskeiding van die Kaapse gordelakkedis, C. cordylus, ook ondersoek.
Die femorale en generasieklierafskeidings van C. giganteus en die femorale
klierafskeidings van C. cordylus is chemies gekarakteriseer deur van analitiese
tegnieke, naamlik gaschromatografie, lae resolusie GC-MS, GC-HR-MS, MO- TMS
derivatisering en retensietydvergelyking, gebruik te maak. Talle verbindings is nie
geidentifiseer nie omdat hulle in 'n baie lae konsentrasie in die afskeidings voorkom,
en/of saam met ander komponente elueer, wat veroorsaak dat daar nie massaspektra
vir hierdie suiwer komponente verkry kon word nie.
Verbindingstipes wat in die afskeidings voorkom, sluit die volgende in:
Karboksielsure - versadig en onversadig
Alkohole
Ketone
Aldehiede - versadig en onversadig
Esters - versadig en onversadig
Koolwaterstowwe - versadig en onversadig
Nitriele
Amiede - versadig en onversadig
y-Laktone
Skwaleen
a-Tocopherol
Steroiede Kwantitatiewe analises van die femorale en generasieklierafskeidings van verskeie
ouvolk akkedisse het getoon dat daar duidelike kwantitatiewe verskille tussen die
afskeidings van mannetjies en wyfies is (in die geval van die femorale
klierafskeidings), maar dat daar geen duidelike patroon in die verskille tussen die
femorale en generasieklierafskeidings van individuele akkedisse van dieselfde geslag
is rue. Daar is kwalitatiewe seisoenale verskille tussen die femorale klierafskeidings
van individue van C. giganteus gevind.
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An analysis of the Cordylus Polyzonus complex (Reptilia : Cordylidae) in the South-Western CapeBadenhorst, N. C. 03 1900 (has links)
Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 1990. / Mouton and Oelofsen (1988) suggested that melanistic cordylid populations in the southwestern
Cape represent relict, cold-adapted populations which evolved under adverse
climatic conditions during the Last Glacial Period, 18000-16000 BP. The first section of
this study was undertaken to test their model for the evolution of melanism in the cordylid
species, Cordylus polyzonus. For this purpose, geographic character variation among
populations of Cordylus polyzonus in the region south of 32°15' latitude and west of 19015'
longitude was investigated. Variation in 122 external morphological characters was analysed
in 306 specimens from 93 localities. Although no inter-locality variation was observed in
most of the characters, a high degree of concordancy was observed in the geographical
variation of three headshield characters. These three headshield characters are considered
non-adaptive and can accordingly be regarded as good indicators of genealogical
relationship. Since they varied together with other adaptive characters such as melanism and
body size, it can be concluded that geographically isolated melanistic populations of
Cordylus polyzonus represent relicts of a once larger melanistic population. The data
underscore the Mouton-Oelofsen hypothesis for the evolution of melanistic cordylid taxa in
the south-western Cape.
A further corrolary of the Mouton-Oelofsen hypothesis, is that melanistic cordylids are
presently restricted to cool enclaves. This assumption was evaluated in the second section of
this study by analysing prevailing climatic conditions associated with the occurrence of
extant melanistic populations of the genera Cordylus and Pseudocordylus in the southwestern
Cape. Climatic data were obtained from 123 weather stations in the study-area. A
close correspondence was found between the distribution of melanistic populations along the
westcoast and the primary upwelling zones of the southern Benguela Current. Lower mean
daily temperatures and a high incidence of advective sea fog on the adjacent coastal regions
are direct effects of these cold upwelled waters. Likewise, montane melanistic populations,
occurring at relatively high altitudes along the extreme western borders of the Cape Fold
Mountains, also experience lower mean daily temperatures and a high incidence of
orographic fog and cloud cover. Melanistic cordylid populations therefore generally have to
4.
contend with relatively exposed environmental conditions of low temperature and limited
solar radiation due to the filtering effect of fog and cloud cover. The fact that all the
melanistic taxa in this region occur as small isolated populations limited to cool enclaves,
suggests that they are presently in a contracted state under strong environmental pressure. It
is postulated that palaeoclimatic conditions very similar to climatic conditions presently
prevailing in these enclaves were experienced over the entire western coastal region, at least
as far as the Orange River, during the Last Glacial Maximum when melanism probably
evolved. Our results therefore corroborate the Mouton-Oelofsen hypothesis that isolated
melanistic cordylid populations represent cold-adapted relicts.
One would accordingly expect melanistic populations to posses some enhanced ability to
absorb infrared radiant heat to cope with these conditions of limited sunshine and lower
temperatures. In section three of this study, differences in dorsal skin reflectivity between
melanistic and turquoise ~. polyzonus populations were quantified. Furthermore, the
physiological ability of this species to change body colour was investigated, as well as
ontogenetic colour change. Significant differences in dorsal skin reflectivity existed between
melanistic and turquoise specimens in the 500-1300 mjl spectral range, demonstrating the
greater heat-absorbing capacity of melanistic populations. The data underscore the MoutonOelofsen
model that melanistic populations are "cold-adapted" relicts. Furthermore,
ontogenetic colour change is a real phenomenon in the melanistic variation of C. polyzonus.
In this respect it is unique among the melanistic cordylid taxa in that ontogenetic colour
change seemingly does not occur in the other forms. Experiments to investigate short term
colour change in response to different temperatures regimes, produced no conclusive results.
On the other hand, seasonal colour changes could be demonstrated for both melanistic and
turquoise specimens, indicating that this species has the physiological capacity to change
colour. It is, however, believed that geographic colour variation in ~. polyzonus cannot be
attributed to this capacity, but is rather the result of selection over time. This view is
underscored by the results of section one demonstrating that, apart from colour and body
size, melanistic and turquoise forms also differ in certain non-adaptive traits; suggesting that
they do not belong to the same primary gene pool.
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Effective conservation of melanistic lizard species in the Greater Cederberg Biodiversity CorridorJanse van Rensburg, Dahne A. 12 1900 (has links)
Thesis (PhD (Zoology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The Cape Floristic Region (CFR) is a biodiversity hotspot in South Africa, threatened by climate change and various other processes. The Greater Cederberg Biodiversity Corridor (GCBC) is a conservation area incorporating both public and private land, providing a practical and effective solution to conserve biodiversity in the CFR. This area is also home to two of the eight melanistic cordylid lizard species found in south-western South Africa. One of the herpetological conservation targets identified for the GCBC was an understanding of the ecology of melanistic cordylid populations with particular reference to global environmental change.
Most melanistic cordylids occur in cool coastal and montane localities, and it was suggested that melanism has a thermoregulatory function in these species. The first aim of this study was to determine the climatic conditions with which melanistic cordylids are currently associated. Several melanistic cordylid populations showed a distinct association with a high incidence of fog and cloud cover, underscoring the thermal melanism hypothesis, which predicts that melanistic lizards should occur in cool environments. Several other populations, however, did not show such an association.
The next aim was thus to compare habitat use and morphology among 10 melanistic cordylid populations. Individuals of the northern population of Pseudocordylus capensis and the Cordylus peersi population occurred in the warmest environments, used significantly higher rock formations, and had relatively longer limbs than those of other melanistic populations. Having a morphology that allows for flexibility in habitat use, may enable species such as P. capensis to overcome the constraints of melanism in warm environments.
Being melanistic may result in decreased activity times in warm environments. The variation in habitat thermal quality and daily activity patterns of two melanistic cordylid species with different morphologies and habitat preferences, occurring sympatrically, was investigated. During summer, high rocks provided a better thermal quality habitat to P. capensis than small rocks, and P. capensis had a longer activity period than C. oelofseni. This suggests that the thermal opportunities provided by high rock enables P. capensis to increase its activity time.
The impact of terrestrial and aerial predators can help shape body armour in lizards, with those species more exposed to aerial predators being faster and less armoured, and those more exposed to terrestrial predators being more heavily armoured. The degree of body armour in melanistic cordylids and their non-melanistic relatives was investigated. Melanistic members of the cordylus-niger-oelofseni and C. polyzonus clades had less armour than their non-melanistic relatives, supporting the prediction that melanistic cordylids basked more and were more exposed to aerial predators than non-melanistic lizards. An increase in body armour in C. peersi indicated exposure to terrestrial predators, whereas P. capensis had a reduction in body armour, indicating exposure to aerial predators. Little body armour, together with a slender morphology and long limbs, may thus enable this species to move with ease on large boulders and scale vertical surfaces to successfully avoid predators.
Pseudocordylus capensis displayed much greater movement rates during activity than other cordylids. A less sedentary foraging strategy may be a prerequisite for life on large, barren rock surfaces where food availability may be low or not uniformly distributed. Both males and females of this species also had large home ranges, a unique phenomenon for cordylids. Space use of males only overlapped marginally, but extensive overlap among males and females and among females, respectively, was observed.
Due to the constraining effect of climate on the distribution of most melanistic populations, melanistic cordylids should be considered as priority species for conservation. While P. capensis is pre-adapted for survival in warm climates, it is dependent on the availability of suitable habitats. The GCBC would thus play an important role in the conservation of this species’ habitat. / AFRIKAANSE OPSOMMING: Die Kaapse Blommeryk (KBR) is ‘n “biodiversity hotspot” in Suid-Afrika wat deur klimaatsverandering en verskeie ander prosesse bedreig word. Die Groter Cederberg Biodiversiteitskorridor (GCBK) is ’n bewaringsarea wat beide openbare en privaatgrond inkorporeer, en ’n praktiese en effektiewe oplossing tot die bewaring van biodiversiteit in die KBR bied. Twee van die ag melanistiese gordelakkedisse wat in suidwestelike Suid-Afrika aangetref word, kom ook hier voor. Een van die herpetologiese bewaringsdoelwitte vir die GCBK was om insig oor die ekologie van melanistiese gordelakkedis populasies met verwysing na globale omgewingsveranderinge in te win.
Die meeste melanistiese gordelakkedisse kom in koel kus- en berggebiede voor, en daar is voorgestel dat melanisme ‘n termoregulerende funksie by hierdie spesies het. Die eerste doel van die studie was om die huidige klimaatstoestande waarmee melanistiese gordelakkedisse geassosieer word, te bepaal. Verskeie melanistiese gordelakkedis-populasies het ‘n duidelike assosiasie met mis en wolkdekking getoon, wat die termiese melanisme hipotese se voorspelling dat melanistiese akkedisse in koue omgewings moet voorkom, ondersteun. Verskeie ander populasies, het egter nie so ‘n assosiasie getoon nie.
Die volgende doel was om habitatgebruik en morfologie tussen 10 melanistiese gordelakkedispopulasies vergelyk. Individue van die noordelike populasie van Pseudocordylus capensis en Cordylus peersi het in die warmste omgewings voorgekom, het relatief langer ledemate gehad en beduidend hoër rotsformasies as ander melanistiese populasies benut. ’n Morfologie wat buigsame gebruik van die habitat toelaat, kan sommige spesies soos P. capensis in staat stel om die beperkinge van melanisme in ‘n warm omgewing te oorkom.
In warm omgewings mag melanisme tot ’n afname in aktiwiteitstye lei. Variasie in termiese kwaliteit van die habitat en daaglikse aktiwiteitspatrone van twee melanistiese spesies, met verskillende morfologieë en habitatvoorkeure, wat simpatries voorkom is bestudeer. Gedurende somer het hoë rotse ‘n beter termiese kwaliteit habitat aan P. capensis verskaf as die klein rotse, en P. capensis het ‘n langer aktiwiteitsperiode as C. oelofseni gehad. Dit stel voor dat die termiese geleenthede wat deur hoë rotse verskaf word, P. capensis in staat stel om sy aktiwiteitsperiode te verleng.
Die invloed van terrestriële en lugpredatore kan help om liggaamspantser in akkedisse te vorm. Spesies wat hoofsaaklik aan lugpredatore blootgestel is, is vinniger en het minder pantser, terwyl spesies wat hoofsaaklik aan terrestriële predatore blootgestel is, meer pantser het. Die graad van pantser in melanistiese gordelakkedisse en hulle nie-melanistiese naasverwantes is ondersoek. Melanistiese lede van die cordylus-niger-oelofseni en C. polyzonus klades het minder pantser as hulle nie-melanisties naasverwantes gehad, en ondersteun die voorspelling dat melanistiese gordelakkedisse meer in die son gebak het en meer aan lupredatore blootgestel was. ’n Toename in pantser by C. peersi dui op blootstelling aan terrestriële predatore, terwyl P. capensis die minste pantser van alle melanistiese gordelakkedisse het, wat dui op blootstelling aan lugpredatore. Min beskerming, tesame met ‘n lenige morfologie en lang ledemate, mag dus hierdie spesie toelaat om gemaklik oor groot rotse en vertikale oppervlaktes te beweeg en roofdiere suksesvol te vermy.
Pseudocordylus capensis het groter bewegingstempo’s tydens aktiwiteit as ander gordelakkedisse getoon. ‘n Meer beweeglike voedingstrategie mag ook ‘n voorvereiste wees vir ‘n lewe op groot, leë klipoppervlaktes waar voedselbeskikbaarheid dalk laag kan wees en nie eweredig versprei is nie. Beide mannetjies en wyfies het ook groot tuisgebiede gehad, ’n unieke verskynsel by gordelakkedisse. Mannetjies se ruimtes het slegs marginaal oorvleuel, terwyl daar heelwat oorvleueling tussen mannetjies en wyfies se ruimtes was. As gevolg van die beperkende invloed van klimaat op die verspreiding van die meeste melanistiese populasies, moet melanistiese gordelakkedisse as prioriteitspesies vir bewaring beskou word. Terwyl P. capensis pre-aangepas is vir oorlewing in warm klimate, is hierdie spesie afhanklik van die beskikbaarheid van gepaste habitatte. Die GCBK sal dus ’n belangrike rol vervul in die bewaring van die habitat van hierdie spesie.
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