Reproductive biology of the Prickly Forest Skink, Gnypetoscincus queenslandiae, an endemic species from northern Queensland

8 Pages·1993·2.2 MB·

by  Michael Cunningham

REPRODUCTIVEBIOLOGY OFTHEPRICKLY FOREST SKINK, GNYPETOSCINCUS
QUEENSLANDIAE, AN ENDEMIC SPECIES FROM NORTHERN QUEENSLAND
MICHAELCUNNINGHAM
Cunningham,M. 1993 1224: ReproductivebiologyofthePricklyForestSkink,Gnypetos-
ciVicM^ queenslandiaCy an endemic species from northern Queensland. Memoirs of the
QueenslandMuseum34(1):131-138.Brisbane. ISSN0079-8835.
Examination of morphology, reproductive state and skeletochronological markings in
specimensofarainforestskink,Gnypetoscincusqueenslandiae,intheQueenslandMuseum,
revealsasexratioof 1:1.5 (<?(3:9 9); thatthe sexescannotbedistinguished byany single
mm
morphologicaltrait; femalesmatureatabout55 (SVL);andimmaturefemalesproduce
many small (<2mm diameter)ovarian follicles. As femalesapproach maturity increasingly
largeovarian follicles are produced, but in mature females the numberofovarian follicles
produced is independent of size. Clutch size increases with size of mature females. The
numberofvitellogenic folliclesproducedissignificantlycorrelatedwithclutchsize.Breed-
ingisseasonalontheAthertonTableland. Asuggestedreproductivecycleforthisviviparous
skinkontheAthertonTableland,ispresented.Asignificant1inearregressionindicatesahigh
correlationbetweensizeandthenumberofhaematoxylinophiliclinesintransversesections
of the femur. Gnypetoscincus queenslandiae, rainforest ecology, reproduction,
skeletochronology, Scincidae.
MichaelCunningham, DepartmentofZoology& CentreforConservationBiology, Univer-
sityofQueensland, Queensland4072, Australia; 14September, 1993.
A well preserved museum specimen, accom- queenslandiae for later use in ecological and
paniedbyaccuraterecordsoflocationanddateof genetic models ofthe effects ofhabitatfragmen-
capture,providesasnapshotofananimal’sphysi- tation.This wasdonethrough theexaminationof
cal stateataparticulartime. Acollection ofthese a series of this species in the Queensland
specimens gives a broader picture of seasonal, Museum.Detailsofthesespecimensareavailable
sizerelated andgeographicvariation inapopula- from theQueenslandMuseum database.
tionoftheseanimals.Inthiswaymuseumcollec-
METHODS
tions may provide valuable information on the
ecology ofcryptic orpoorly known species.
One such species is the Prickly Forest Skink, G. queenslandiae (n=160) from 24 sites in the
Gnypetoscincus queenslandiae. This nocturnal, Wet Tropics were examined. The majority
livebearinglizardisendemictotherainforestsof (n=118) were from 18 sites on the Atherton
&
theAustralianWetTropics(Cogger, 1992;Nix Tableland 145'^30’-145°45’E),
Switzer, 1991). Because it is found in or under an undulating plateau with an altitude of 700m-
rottinglogs,thisspeciesisdifficulttostudyinthe 900m. Twenty-nine skinks were collected from
field.Greer(1989)describes G. queenslandiaeas upland sites to the north (three sites: n=23) and
‘one ofthe most ecologically buffered terrestri^ south (one site: n=6) ofthe Atherton Tableland.
reptiles in Australia’ and continues ‘given this A further thirteen were collected from two
presumably relatively aseasonal microhabitat, lowland sites: one at a similar latitude to the
onecouldaskwhathashappenedtothosebiologi- AthertonTableland(BellendenKer: n=6)andone
cal activities that are generally seasonal in less site in the northern Wet Tropics (Daintree: n=7).
buffered species’. Skinkshadbeenobtainedbetween 1963and 1992
In several areas ofthe WetTropics, especially in February, April, June, September, November
the Atherton Tableland, much of the original and December. Samples collectedfromthe same
forest has been cleared for agriculture, grazing site at different times were available from only
rsasaltniaudnndfdyosireaoetsefttli,teshmaaiesncndthoamib(siWmtitoanhtnutsefirrnaahegastmbueiiantlt.taa,nabttl1ei9oo8fsn7p.t)eh.ceTihrGe.eesmqfaaouiirenmeitnnoh-gef fsmopeTuearhcseisuimstreenesno.duwta-wvsietnththelneenldgeitcshster(coStnVeidLc)foocrfaleelxaiacpmheirsnska.itnikEoanwcaohsf
this project was to elicit information on the the reproductive tract. Males were distinguished
reproductive tfiology and demography of G. from females by theabsence ofoviducts running
132 MEMOIRS OFTHEQUEENSLANDMUSEUM
forwardalongthebodywallfromthegonads,the individual. Canonical-Discriminant Analysis
absence of enlarged ovarian follicles and the may demonstrate separation among groups that
presence of a cream coloured epididymis. For appear indistinguishable in analyses of single
each male, only a qualitative assessment of the variables, due to overlap between groups in the
state (turgid or flaccid) and size (small or en- range ofeach morphological character. A series
larged) oftheepididymis wasrecorded. Females of meristic measurements (SVL, head length,
were recorded as gravid (possessing oviducal head width, length ofthe left tibia, andlength of
eggs) or not gravid (without oviducal eggs). In the left fourth toe) and scale counts (lamellae
addition, the following measurements of under the left andright fourth toes, left and right
reproductivestatewererecordedforeachfemale: supra-ocular scales, para-vertebral scales, and
I - Clutch size (the number ofoviducal eggs); II nuchal scales) gathered on these skinks for
mm
number of greatly enlarged (>2 diameter) another study were submitted to the procedure
ovarianfollicmlems;IIInummbmerofenlargedfollicles, ‘CANDISC’ in the SAS statistical analysispack-
between 1.5 and2 indiametemr;mIV num- age (SAS InstituteInc, 1985). In addition to this
ber ofovarian follicles between 0.5 and 1.5 multi-variate analysis ‘CANDISC’ provides
mmindiameter; andV numberofsmall follicles, analysis of variance (ANOVA) comparisons of
mm
less than 0.5 in diameter. groups for each morphological variable (SAS
These classes were deterntined from the ob- instituteinc., 1985).Thesetestthehypothesisthat
served size distribution of developing follicles, differences between the sexes cannot be distin-
and correspond to the follicular growth stages guished from variation within each sex.
described forthe Diamond-backed WaterSnake, Nix & Switzer (1991) report size variation in
Natrixrhombifera^(Betz, 1963)andthelatterfive populations of G. queenslandiae from different
classesdescribedforseveraltropicalsnakes(Zug, locations. The SAS procedure ‘GLM’ (SAS in-
1979). Oviducal eggs (class 1) were a golden stitute inc., 1985) was used to investigate size
yellowcolourandalwayslargerthan5 mm;class (SVL) differences between sampling sites by
II follicles were a creamy yellow colour; classes one-way ANOVA. This analysis included only
III, IV and V were white. The diameter of each those locations from which fiveor moresamples
ovarianfolliclewasdeterminedusingadissecting had been collected. The mean size of gravid
microscope. females (withoviducaleggs)wascomparedwith
To assess the relationship between size and thatofallotherfemalesfromthe AthertonTable-
relative age in G. queenslandiae , the left femur land,usingStudent’st-test,generatedbytheSAS
from fourteen specimens (representative of the ‘TTEST’ procedure (SAS institute inc., 1985).
rangeofsampling locations and size within each This analysis teststhenull hypothesis thatgravid
sex), was removed for skeletochronological females do not differ in size fromotherfemales.
analysis. Each femur was decalcified in formic Pearson product-moment correlation coeffi-
acidandformalin,andvacuumembeddedinwax. cients, generated by the SAS procedure ‘CORR’
Transverse sections were taken from the mid- (SAS instimte inc., 1985), were used to compare
diaphysis ofthese bones, mounted on slides and size of female skinks with number of eggs or
stained for 15 minutes with Delafield’s
ovarian follicles carried by those females, for
haematoxylin and for 10 seconds with Eosin. eachclass defined above. Theseanalyses testthe
These were examined under a compound micro-
hypothesis that the number ofeggs and ovarian
sstcaoipnee,d tcoonrceecnotrrdictrhiengnsuimnbtehre cofomhpaaecmtatbooxnyelionf ftoesltliocflehsoimsongoetnceoirtreylawtaesdwuistehdStoVLin.veAstCihgiatseqtueamr-e
each femur.
poralvariationintheproportionofgravidfemales
in the Atherton Tablelands samples, and to test
ANALYSES
theprobability thatthis variation could be due to
random sampling.
A Chi square test was used to compare the Finally, the procedure ‘REG’ in SAS (SAS
observed sex ratio in the total sample, with an institute inc., 1985) was used to generate simple
etxwpeeecntesdex1e:s1 rawteiro.eMoarsspehsosleodgibcyalCdainfofneircenacle-sDibse-- rliinnegasrargeagirnesstsisoinzes,oSfVtLhe,nfuomrbaeilrsoafmfpelmeosraalndbofnoer
criminant Analysis. This analysis finds the those from the Atherton Tableland alone. These
maximumdifferencebetweengroups(inthiscase regressions areusedtopredicttheexpectednum-
males and females) based on a weighted com- beroffemoral bone rings from a skink ofknown
binationofvariablecharacters,measuredoneach size.
REPRODUCTIVEBIOLOGYOFTHEPRICKLYFORESTSKINK 133
(V)
FOLLICLES
SMALL
(III)
FOLLICLES
ENLARGED
Sex Ratio, Sexual Dimorphism and Size
Variation
In the sample there were 64(5c5 and 94$ 9.
Individuals ranged from 30 mm to 84 mm(SVL)
(mean±sd: SVL=58.4±10.9 mm), but it was not
(I) possible to determine the sex of the two skinks
SIZE smaller than 34 mm SVL. This gives a sex ratio
of 1:1.47 which differs significantly from the
CLUTCH expected 79:79 ratio (X^=5.70, df=l, p<0.02),
indicating an overall bias towards females in this
collection.
The canonical discriminant analysis
demonstrated significant separation between
males and females in muiti-dimensional mor-
phological space (Exact F=6.30, df=ll,
p<0.0001). This separation was generally not
reflected in the univariate tests ofsexual dimor-
phism, with only the number of nuchal scales
FIG. l(A-E). Plotofclulchsizeandnumberoffollicles (NTOT - defined here as the number of scales
ineach sizeclass againstSVLforall females. posterior to, and in contact with, the parietal
134 MEMOIRSOFTHEQUEENSLANDMUSEUM
Table 1. Correlation between number of oviducal SVL=43.6±6.3 mm) than those from other loca-
eggs/ovarian follicles and the snout-vent length tions, whilst those from Major’s Mountain
(SVL)ofallfemales,maturefemales(SVL>55mm) (17°38’S 145°32’E) were generally larger (n=5:
andgravidfemales(clutchsize>0). SVL=72.9±3.3 mm).
(n) (r) (p) Sizeand Reproduction
All 6S larger than 50 mm SVL displayed
size mm
Pearsonproduct-momentcorrelation Significance enlargedepididymides(approximately4.5 in
co-efficient probability
diameter), which presumably indicates sexual
Sample maturity. None smaller than 45 mm SVL pos-
sessed an enlarged epididymis. Among the 6S
ALLFEMALES mm
largerthan50 SVL,epididymideswereeither
Clutchsized) 91 0.494 0.0001 turgid or flaccid with no clear seasonal or
Vitellogenicfollicles(II) 88 0.622 0.0001 geographic trends. This may indicate a stage in
EnlargedfoIlicles(III) 88 0.472 0.0001 thereproductivecycle,suchastheproductionand
DevelopingfolliclesdV) 88 0.508 0.0001 storageofsperm, ormay be an artefactofcollec-
tion and fixation.
Smallfollicles(V) 88 -0.349 0.0009
MATUREFEMALES Ofthe71 $ 9 fromtheAthertonTableland,25
were gravid (mean SVL=66.8±5.0 mm) and 46
CViltuetlclhogseinzeic(1f)ollicles(II) 6518 00..125587 NNSS werenot(meanSVL=5m5m.5±11.9mm).Thesmall-
estgravidskink55.5 (SVL);thelargest(non-
Enlargedfollicles(III) 58 0.130 NS gravid) was 78.7 mm (SVL). Using an estimate
Developingfollicles(IV) 58 -0.042 NS of T, modified to account for unequal variance
Small follicles(V) 58 0.124 NS between groups, gravid 9 9 were found to be
GRAVIDFEMALES significantlylargerthanothers(modifiedt=-5,48,
Clutchsized) 36 0.390 0.019 df=65.9,p<0.()()01).Nospecimensmallerthan55
Vitellogenicfollicles(II) 33 0.299 NS nun (SVL) hadany class I orIIovarian follicles.
Enlargedfollicles(ni) 33 0.115 NS Class III follicles weremfmound in only three 9 9
DevelopingfoHicles(lV) 33 -0.021 NS (12%) smallerthan55 (SVL), Fig. 1C.
The correlation analysis was performed on
Small follicles(V) 33 -0.231 NS three nested groups: all 9 9, to investigate
general size related trends in reproductive state;
scales) showing significant differences between only 9 9 >55 mm SVL, to exclude immature
males and females (F=6.11, df=l, p=O.015). skinks 9 9; and only gravid 9 9 (clutch size >
Females tend to have fewer nuchal scales 0), to compare skinks in a similar physiological
(mean±sd, ? 9:NTOT=16.64±1.83; 6 cJ:NTOT
=17.43±1.66).However,the $ range(NTOT=13
to 21) is contained in that of (5 c3 (NTOT=l1 to
21) and, as this is a discrete character, the ex-
NTOT
pected value of forboth is 17.
Although no significant size differences were
detectedbetweenthesexes intheaboveanalyses,
significant SVL differences were found among
sample locations in the anova (F=4.39, df=13,
p<0.0001). To further explore these differences
the mean ofeach population was compared with
that of each other population using Tukey’s
studentized range tests calculated by the SAS
procedure ‘GLM’ (SAS instituteinc., 1985).The
overalltype1errorrateforthesecomparisons(the
rale at which results are falsely accepted as sig-
nificant) was restricted to 0.05. Several samples FIG. 2. Temporal variation in percentage of females
were found to differ significantly in SVL. The fromtheAthertonTablelandcarryingoviducaleggs.
skinks from Dowlings’ Fragment (17°23’S Sample sizes are given for each month from which
145°4rE) are smaller on average (n=7: collections wereavailable.
REPRODUCTIVEBIOLOGYOFTHEPRICKLYFORESTSKINK 135
condition. Pearson product-moment correlation encased in the egg membrane, was not sur-
coefficients for each of these comparisons are roundedbyyolk.ThisunbornskinkhadaSVLof
presented(Table 1). Inthecomparisonsincluding 25.9 mm, which was 4 mm smaller than the
all ? $, SVL was significantly correlated with smallestjuvenileskinkexamined in this study.
clutch size and each class offollicles (Table 1). This apparent seasonality ofreproduction sug-
Clutchsizeandthenumbersofclass II,IIIandIV geststemporal variation intheaverage size ofG.
ovarian follicles increase with SVL, the number queenslandiaeon theAthertonTableland,result-
ofclassVfolliclesdecreaseswithSVL,however, ing from an annual pulse of recruitment. The
there is considerable variation between similarly averageSVLofG. queenslandiaecollectedfrom
sized lizards (Fig. lA-E). When immature $ V the Atherton Tableland and examined here,
areexcluded fromthecorrelation analysis, varia- showsnosuch pattern,beinghighestinApriland
tion in the number ofeggs and follicles appears November, and lowest in September. In some
to be independent of SVL (Table 1). Among seasonally breeding species the observed sex
gravid $ 9 clutch size is significantly and posi- ratiovarieswith thereproductivecycle,asgravid
tivelycorrelatedwithSVL(Table 1);largegravid females are often more obvious than other in-
$ $ generally carry more eggs than smaller dividuals (Schwarzkopf & Shine, 1992; Sim-
gravid 9 9 (Fig. lA). Although the number of botwe, 1985). In this study the observed
vitellogenic follicles (II) was not significantly proportion of females varies between 50% in
correlated with SVLin gravidfemales (Table 1), February and 73% in December, however, both
it was significantly correlated with clutch size months have small sample sizes (n=4 and n=ll
(n=33, =0.536, p=0.001). respectively). A chi square test of homogeneity
shows that there is no evidence for temporal
Female ReproductiveCycle, variationinthesexratio()c2=l.28df=5p=0.937).
Atherton Tableland
Atleast50%of 9 $ collectedfromsitesonthe BoneHistologyand Skeletochronology
AthertonTablelandinSeptember,Novemberand The bone structure of G. queenslandiae is
&
Decemberweregravid(Fig.2).Neitherofthetwo similar to that of other squamates (Castilla
9 9 collected in Februaryweregravid. Onlyone Castanet, 1986; Ricqles, 1976; Enlow, 1969). At
of thirteen 9 9 collected in April, and one of mid-diaphysisaweakly vascularornon-vascular
seventeen 9 9 collected in June, were gravid cortex of periosteal bane surrounds an almost
(Fig. 2). The Chi square test of homogeneity hollow medullary cavity lined with endosteal
indicates statistically significant temporal varia- bone. The periosteal bone consists ofa series of
tion in the proportion of gravid females peripherally deposited lamellae, among which
(X^=22.628, p=0.000). areregularlyarranged,haematoxylinophilicrings
A temporal trend was also evident in the or ‘rest lines’. Endosteal bone results from the
development ofeggs within gravid females. The resorption and reworkingoftheinnercortex and
single gravid specimen collected in June carried so the amount of endosteal increases with the
smalleggs (average egg length 6.0 mm). Several diameterofthe femur. The process oferosionof
non-gravid 9 9 collected in June carried very periosteal bone and substitution with endosteal
large, class II, follicles (between 4 mm and 6 boneresults in theobliterationofsomerestlines.
mm),whichwereofsimilarsizetosmalloviducal Linear regressions, predicting the number of
eggs and were not found in females collected at restlinesfromSVL, werestatisticallysignificant
other times. In gravid 9 9 collected in Septem- for both the total sample and for the seven in-
ber, eggs were larger (average length =10.7±L2 dividuals from the Atherton Tableland alone (all
mm)butshowednoobvioussignsoffertilisation. samples - R^=0.76, p=0.0001; Atherton samples
Eggs in gravid females collected in November -R2=0.77, p=0.01)(Fig 3).
and December were ofa similar size to those in
DISCUSSION
mm)
September (average egg length 1 1.8±1.7 mm
and carried developing embryos, up to 5
long,surroundedbyyolk.Thegravidfemalefrom The results ofthis study allow broad estimates
April (J31057) was the only individual in the of parameters which are vital to the successful
entiresamplecanyingwelldevelopedyoung,and application of population models, and which
theonlygravid individual tohaveaclutchsizeof would be difficult to measure under field condi-
one. The single foetus found in this female ap- tions. These factors include the sex ratio, the
peared to be fully developed and, although still clutch size produced, the size at which maturity
136 MEMOIRS OFTHEQUEENSLANDMUSEUM
sizedifferenceswerefoundbetweenlatitudinally
separated upland populations orbetween upland
and lowland populations, however, the small
sample sizes from areas other than the Atherton
Tableland may be insufficient to detect suchdif-
ferences. Considerablegenetic variationhas also
been detected between geographically separated
populations of G. queenslandiae (Moritz et al.,
1993). The degree of congruence between this
genetic variation and morphological variation
couldnotbeexaminedbecauseoflimitedsample
sizes from matched sites and possible collector
bias.
Reproductive Biology
Sexual maturity in females is attained at ap-
mm
proximately55 SVL. Malesprobablymature
FIG. 3. Plot of estimated number of haematoxylin
stained femural bone rings against SVL for in- amtma slightly smallersize. Skinks smallerthan 50
dividuals from all locations. Open symbols ~ 66; were uncommon in thiscollection. This may
closedsymbols = $ $. The leastsquaresregression reflect collection bias, rapid growth to maturity,
forall individuals(bonerings=0.12±0.02 X SVL- that juvenile skinks are more difficult to locate
1.49±1.19)depicted aboveissignificant(R^=0.76, than mature animals, or a combination of these.
p < 0.001). The regression including only samples In mature females ovarian follicles are always
from the Atherton Tableland was also significant presentbutvitellogenesisisseasonal.Developing
(bone rings = 0.09 ±0.02 X SVL+ 0.13 ±1.3, R^ = follicles greatly outnumberthe numberofovidu-
p<
0.77, 0.01). cal eggs, presumably with the remaining vitel-
logenicfolliclesbeingresorbedafterthebreeding
is attained and the relationship between size and season.AccordingtoShine(1977)theproduction
age. These results and others, such as the degree ofmore vitellogenicfollicles than areovulatedis
of sexual dimorphism and spatial variation in ofadaptivevalue,allowinganindividualtoadjust
size, would complement ecological and genetic clutchsizeaccordingtoenvironmentalconditions
studies ofG. queenslandiae. at the time of ovulation. These additional en-
larged follicles may also allow multipleclutches
Sex Ratio
Thereappears to beaslightbiasinthesex ratio Vitetlogenesis
towards females. As there is distinct temporal OviJation
variation in the proportion of gravid females,
albeiton small numbers, but no similarvariation Fertilisationanddevelopment
in the sex ratio, it seems that this observed sex Parturition
ratio bias can not be attributed to the capture of
more gravid females than other individuals. The
sex ratio ofG. queenslandiae would be difficult
todetermine in thefieldas theredonot appearto
be any clear morphological differences between
the sexes, although one possible method is the
eversion of male hemipenes described by
Schwarzkopf(1992).
Variation in Size
Significant size differences were found be- FIG.4. ReproductivecycleofG.queenslandiaeonthe
tween several populations. Although these may AthertonTableland. Vitellogenesispeaksearlyinthe
be the result of non-random sampling, it does mild, dry season, and is followed by ovulation and
appear that skinks from the southern Atherton fertilisationmid-year. Developmentofyoungoccurs
Tableland, particularly from Majors Mountain, late in the dry season and throughoutthe warm wet
are larger than those elsewhere. No significant season, with parturition late inthewet season.
REPRODUCTIVEBIOLOGYOFTHEPRICKLYFORESTSKINK 137
withinabreeding season.The lattersuggestion is logenesis becomes apparent in June and is fol-
supported by the observed correlation between lowedbyovulationinJuneandJuly. Fertilisation
clutch size (I) and the number of vitellogenic anddevelopmentoffoetusesoccursbetweenSep-
follicles (ID. tember and January. Parturition occurs between
The correlations between the numbers of February andApril andis probably accompanied
ovarian follicles and SVL, when all females are by regression of the vitellogenic follicles that
considered, and the lackofany correlations with were not ovulated. The time at which mating
SVLwhen onlyfemaleslargerthanSVL=55 mm occurs could not be inferred from the results of
are considered, indicates that the number ofen- this study, as females may store sperm for a
&
larged follicles (III IV) produced by immature considerable time before fertilisation (Fitch,
females increases with size until maturity. The 1982), in this caseovulation.
negativecorrelationbetweenthenumberofsmall Reproductiveeyelesinothertropicalskinksare
follicles (V) and SVL, when immature females highly variable both between and within species
are included, suggests that the total number of (Fitch, 1982). The primary determinant of
folliclesisrelatively constant throughoutlife. As seasonalityofreproduction in tropical skinksap-
females grow towards maturity some class V pearstobetheseasonalityofprecipitation(Fitch,
follicles become enlarged, and so the number of 1982). Precipitation on the Atherton Tablelands
follicles thatremain smalldecreases. is distinctly seasonal with average rainfall over
mm
Asinstudiesofothersquamates(Schwarzkopf, 250 in January, February and March, and
mm
1992; Simbotwe, 1985; Shine, 1977), clutchsize below 50 in June, July, August, September
in G. queetislandiae is correlated with size of andOctober(measuredatKairiexperimental sta-
females. Lifehistory theorypredicts thatfemales tion; AGPS 1988). Temperature is also seasonal
should maximise lifetime reproductive output, on the Atherton Tableland and varies between a
and that it may be advantageous for a female to mean daily minimum of 10.9°C, with occasional
useenergyreserves forgrowth ratherthanbreed- frost, in July, and a mean daily minimum of
ing, if the probability of survival is high and 19.5®C in February (Kairi experimental station;
additional growth will substantially increase fu- AGPS 1988). In the reproductive cycle outlined
ture clutch sizes (Schwarzkopf & Shine, 1992). above, embryonic development on the Atherton
The relationship between clutch size and SVL Tableland would occur during the warm, rainy
(Fig. 1A)isconsistent withthis prediction in that season, with parturitionoccurringjust before the
largerfemalesproduceeithersmallorlargeclutch onset of the mild, dry weather (Fig. 4). In other
sizes whilst smaller females only produce small parts ofthe WetTropics, particularly theBellen-
clutches. In each ofthe samplesofG. queenslan- den KerRa. immediatelytotheeastoftheAther-
diae considered here a proportion of ‘mature' ton Tableland, precipitation and temperature are
females (SVL>55 mm) were not gravid. In the less distinctly seasonal and populations of G.
related seasonally breeding, viviparous skink queenslandiae from these areas may have dif-
Eulamprus tympanum, Schwarzkopf (1992) ferentreproductive cycles.
found that variability in reproductive output per
yearwas expressed as variation inoffspringsize,
Skeletochronology
and possibly the proportion of non-breeding
females, whilst the average clutch size remained The number of ‘rest lines’ in the femurs of G.
queenslandiae shows a clear relationship with
constant across years. The lack of replicate
samples from the same sites precluded such an =siz0e.1whXichSVisLro(uFiggh.ly3)a.pAplrtohxoiumgahtetdhebsye:rreessttlliinneess
analyses ofbetween-year variation in this study.
can not be assumed to represent a true index of
age as a result of remodelling of the bone, they
Suggested ReproductiveCycle may be a useful measure of age differences be-
The skinks considered in this study were col- tween skinks (Enlow, 1%9). Mature individuals
lected not only in different months, but also in had at leastfive rest lines and no more than nine.
dwiiftfheirne-nyteyaerarpsa,tstoerintsisfnrootmpobsestibwleeent-oydeiasrtinvgauriisah- lIfinietsirseparsessuenmtedconthsattantthepeirnitoedrsvaolfsgbreotwwtehe,nthreesset
tion. The predictable climate of the Atherton results suggest that maturity in G. queenslandiae
Tablelandandthepatternoftemporal variationin is delayed until quite late in life.
theproportionofgravidfemalesandeggdevelop- In other species, mainly those from temperate
mentsuggestthefollowingseasonalreproductive regions, rest lines are formed semi-annually or
cycle in G. queenslandiae (Fig. 4). Active vitel- annually but not less frequently (Castanet et al..
138 MEMOIRS OFTHEQUEENSLANDMUSEUM
1988). The observed number ofrest lines in G. Australian lizards. Pp 154-155 (Surrey Beatty:
queenslandiae could be used in demographic Sydney)
models as a rough estimate of maximum age, ENLOW,D. H. 1969.Theboneofreptiles. Pp45-80.
&
wahnderleivsekainmkasxrieamcuhmmaotfutreintyyeaatrfsi.veAyseeaxrsraotfioagoef I‘nBiGoalnosg,yCo.f,thBeelRleaiprtsi,haA..VolPaurmseon1s’,.T(.AcS.ad(eedmsi)c,
1:1.5 could be used in this model with 75% of Press: London).
mature females breeding each year (maximum FITCH, H. S. 1982. Reproductive cycles in tropical
numberofgravidfemaleswithSVL>55mm)and reptiles. Occasional papers of the Museum of
each gravid female producing a clutch size of NaturalHistory96:1-53.TheUniversityofKan-
(3.11=average clutch size). Field studies of size sas,Lawrence, Kansas.
specific mortality and population density would MORITZ, C. . JOSEPH, L. & ADAMS, M. 1993
be required to complete thisbasic model. Cryptic diversity in an endemic rainforest skink
(Gnypetoscincus queenslandiae). Biodiversity
ACKNOWLEDGEMENTS and Conservation.2:412-425.
NIX,H. A. & SWITZER,M. A. 1991 Tropidophorus
queenslandiae. P.82. In ‘Rainforest animals.
This project was funded by a Queensland
Museum Student Research Scholarship. Thanks Atlas of vertebrates endemic to Australia’s wet
are extended to Patrick Couper and Jeanette tropics.’ (AustralianNationalParksandWildlife
CfhchaooieonlrslvdltpaeofscZcluuteolegigvngoayianed;cssbv;hatiinctfKodeooanrltosPesoanlutDoprtapfnihoomcerrkipltoeaiCsatnsosensuriBidabprstaloteuceadrrcneee;crcaseiontscmodwktpLi,oCaitrrtLnhhaieaeisotgoDmhJnuaeMossodsbreedoaipuonnthmwdez, RICQLBlSbaeieinElvrodSlivlani,oiegcgrveAsyro...elopCuJAft.at.inril1eboe9&pens7trai6rwrlC.aieyos)tOx..hsn,iLcgiBbnon.oimnnf(emieecaedahnnsni)tcSs,esot.co‘iloMPoenogtpryyipto1Sshf2yof3flmu-oonps1csgo5ity1sli.oiaanunnIamddnl
Series3’. (AcademicPress: London).
Nicole Lee, Craig Moritz, Jeff Miller and an SASINSTITUTEINC 1985SAS/STATuser’sguide,
anonymousrefereeforconstructivecommentson
release 6.03 edition. (SAS Circle: Cary North
themanuscript.
Carolina)
SCHWARZKOPF, L. & SHINE,R. 1992.Theevolu-
LITERATURECITED
tion ofreproductiveeffort in lizards andsnakes.
Evolution46:62-75.
AUSTRALIAN GOVERNMENT PUBLISHING SCHWARZKOPF, L. 1992. Annualvariation in litter
SERVICE (AGPS). 1988. ‘Climatic averages size and offspring size in a viviparous skink.
Australia’.(AGPSPress: Canberra). Herpetologica48:390-395.
BETZ, T. W. 1963 The gross ovarian morphology of SHINE, R. 1977. Reproduction in Australian elapid
theDiamond-backedWaterSnake,Natrixrhom- snakesII.Femalereproductivecycles.Australian
bifera, during the reproductive cycle. Copeia JournalofZoology25:655-666.
4:692-697 SIMBOTWE, M. P. 1985. Sexual dimorphism and
CASTANET. J. NEWMAN, D. G. & SAINT reproduction of Lampropholis guichenoti
,
tGhIeRgOrNoSwt,h,H.ag1e9,88an.Sdkpeolpeutloachtrioonnosltorguicctaulredaotfatohne (SLhaicneer,tilRi.a:&SciEnchimdaane)n.,PHp.11(-e1d6s.),In‘BGiroilgog,gyG.of,
tuatara, Sphenodonpunctatus^ on Stephens and Australasianfrogsandreptiles’.(RoyalZoologi-
LadyAliceIslands,NewZealand.Herpetologica cal SocietyofNewSouthWales: Sydney).
44(1): 25-37 WINTER, J.W., BELL,F.C.,PAHL, L.l. &ATHER-
CASTILLA, M. A. &CASTANET.J. 1986. Growth, TON,R.G. 1987Rainforestclearfellinginnorth-
age and longevity ofLacerta lepida assessed by eastern Australia. Proceedings of the Royal
skeletochronology. Pp33I-336. In Rocek, Z. SocietyofQueensland98:41-57
(ed), ‘Studies in herpetology’. (CharlesUniver- ZUG, G. R., HEDGES, S. B. & SUNKEL, S. 1979
sity: Prague). Variation in reproductive parameters of three
COGGER, H. G. 1992 Reptiles and amphibians of neotropical snakes, Coniophanesfissidens, Dip-
Australia. Pp498^99 (ReedBooks: Sydney) sas catesbyi, and Imantodes cenchoa. Smith-
GREER, A. E. 1989 The biology and evolution of sonianContributionstoZoology No. 300.