This file is part of the following reference:

Braby, Michael (1994) Life history strategies of tropical satyrine butterflies in north-eastern Australia. PhD thesis,

James Cook University.

Access to this file is available from:

http://eprints.jcu.edu.au/10857

Life history strategies

of tropical satyrine butterflies in

north-eastern Australia

Thesis submitted by

Michael F. Braby B.Sc.(Hons) (La Trobe Universitv'\

January 1994

.LVi the degree of Doctor of Philosophy in the

Department of Zocllogy,

James Cook University of North Queensland,

Townsville, Qld. 4811.

Australia

1

Satyrine butterflies delight in sunning themselves in forest glades, letting the sun

kindle to glowing wannth the rich brown colours of their outspread wings, the

underside of which are so well camouflaged that they merge into their

background the moment the wings are closed

Charles McCubbin, 1971

STATEMENT OF ACCESS

I, the undersigned author of this work, understand that James Cook University will make this thesis available for use within the University Library and, via the Australian Digital Theses network, for use elsewhere. I understand that, as an unpublished work, a thesis has significant protection under the Copyright Act and; I do not wish to place any further restriction on access to this work

_____________________________________ ______________ Signature Date

STATEMENT ON SOURCES

Declaration

I declare that this thesis is my own work and has not been submitted in any form for another degree or diploma at any university or other institution of tertiary education. Information derived from the published or unpublished work of others has been acknowledged in the text and a list of references is given. …………………………………………….. ……………………… (Signature) (Date)

IV

Abstract

Three species of satyrine butterflies, Mycafesis jJerseus, M. tern'1inus and M.

siriLIs (Lepidoptera: Nylnphalidae), occur throughout the tropical lowland region

of north-eastern Queensland, Australia. Their ecologies and life history

strategies were examined and cOlnpared, first to deteIlnine how the species

survive the unfavourable dry season when larval food resources (grass)~

frequently become dormant, and second to consider how potential selective

forces may have moulded their life histories.

Sympatric populations of Mycalesis spp. were studied during 1989-1992

at Cardwell, a moist coastal lowland region which is characterised by high

summer rainfall and an aO.11ual winter dry season v.;hich lasts about seven months

on average. The habitat requirenlents and breeding status of these species were

also examined less intensively during the dry season in areas throughout

northern and central Queensland, north of the tropic of Capricorn. Populations

of several other related satyrines (Melaniris, YjJthinlo, H.V/Jocysta) were also

studied in these areas.

The tropical satyrines exhibit three different strategies for dealing with

the unpredictable dry period and associated deterioration of larval food plants

(grass). First, five species (YjJthiJna arc[ous, H~Y/JOcysla nletirius, H. irills, H.

a{liante, H. pseu{lirius) appear to breed continuously, though for most

reproductive activity (as measured by rnature egg number) declines rnarkedly in

the late dry season. Bot11 HyjJocysro frius and H. Inetirius are restricted to less

seasonal and more favourable (wetter) areas but the other three occur widely in

the relatively dry savanna, where they Inay specialise on grass in moister

microenviron.ments. Second, two species (M. ternlil1l1s, M. sirius) live in

predictably moist habitats (rainforest edge and paperbark swampland

respectively) which are buffered from climatic extrelrles; they breed for much of

the season but reproductive activity declines as the dry season progresses and

may cease late in the season. Third, one species (M. jJerseus) is ITIOre

opportunistic, it occurs in drier and more open habitats (savanna) and breeds for

only for a limited interval during the favourable (wet) periods~ during the long

v

dry season adults contract to I110ist refugia and relnain in reproductive diapause.

Rainfall (or some correlate of rainfall such as hun1idity or food plant quality)

appears to regulate diapause in M. !Jerseus.

Regular samples and transect studies at Cardwell showed that relative

abundance of adult Mycalesis spp. increased during the early dry season, peaked

during the dry winter months, decreased in the late dry season and then reached

very low levels with the first significant wet season rainfall. The pattern of

seasonal abundance was broadly synchronous with seasonal changes in grass

moisture content which in turn was linked with rainfall regin1e. Hence the

patterns of seasonality in Mycalesis ITIay be influenced by variation in rainfall

and therefore larval food quality, but other factors likely to influence fluctuation

in abundance are discussed.

Associated with changes 111 breeding phenology and abundance in

Mycalesis were marked seasonal changes in behaviour, body size and

phenotypic variation in the wing underside eyespot elernents. Adult females of

all three species were characterised by smaller eyespots (dry-season form) during

the dry cooler winter, whereas individuals with larger eyespots (wet-season

form) predominated throughout the wet hotter surTImer-tluturTIn months. Dry­

season fOnTIS were typically larger (at least in M. jJerseus and M. ternlinus), less

active, aggregated in moist refugia and were often reproductively donnant

during the late dry season. Wet-season fOllns usually reproduced directly and

rarely entered diapause. The extent of phenotypic change \vas less pronounced

and more gradual in M. sirius and Inost dramatic in M. !J(!rscus. Phenotypic

variation in these butterflies 111ay be a dry season strategy to enhance survival

against natural enemies through crypsis when adults ctiapause.

Spending the late dry season as an adult ITIay ilnprove the capacity of

these satyrines to utilise new growth of grasses at the start of the favourable

period (i.e. first pre-wet season rains), thereby enhancing population growth. It

may also provide addit.ional flexibility to counter the temporal uncertainty of the

wet season, as well as allowing butterflies to avoid grassland fires. However, the

tendency to occupy more favourable habitats for breeding I11ay Inean that these

species are limited in terms of their geographic distribution.

VI

The influence of constant ten1perature on the egg stage of Mycalesis

revealed that maXirTIU1TI survival occurred at 26°C. Eggs of M. jJerseus survived

well between 17 and 35°C, whereas those of M. fern'linus and M. sirius survived"

poorly above 30°C and, in the case of the latter species, belo\v 23°C. Maximum

egg development rat.e occurred at 35°C in M. j.Jerseus and around 30°C in the

two other species. Thus optimal temperatures for developnlent and survival

were higher for M. jJerseus than M. fern-linus and M. ,\)rius.

Under cont.rolled environnlental conditions, M.vcalfsis larvae survived

significantly better on native Kangaroo grass, Thenlecla trjanclra, than when

reared on introduced Guinea grass, PaniCU171 Inaxin-1U171. However, larvae took

substantially longer to develop and attained lower pupal weights on Thelnecla

than on Panicunl. This was especially 11larked in M. sirius. On Panicurn at 25°

C development from egg to adult varied fro111 4().4 d (Inale M. /Jerseus) to 50.4 d

(female M. tern'zinus). Developnlent in M. ,'"liriu.)" was more variable, with larvae

completing either five or six larval instars. Overall, rnales developed

significantly faster than females, and ITI[lles were smaller in size than females in

all three species. Under field conditions populations are thus seasonally

multivoltine, protandrous and se"xually dilTIOrphic with respect to body size.

Availability of sugar (250/0 honey solution) or rotting fruit in the adult diet

of Mycalesis sirius (wet-season fonns) had no significant affect on oviposition

pattern, fecundity, longevity, egg size and reproductive effort. However, in M.

tern"zinus diet had two Inajor effects: availability of sugar increased longevity,

while females fed on rotting fruit tended to tnaintain constant egg weight over

time. Differences in response to adult diet in these two species correspond with

their behaviour in the field: M. sirius adults rarely feed at nectar sources or on

rotting fruit, whereas those of M. lern"li nus readily feed on rotting fruits. Hence,

availability of rotting fnlits to adult M. tern"linu,)' Illay en_hance reproductive

success since fernales appear to produce better quality offspring (i.e. lay larger

eggs over time).

In M. !Jerseus, post-diapausing felnales of the -dry-season fonn had

reduced realised and potential fecundity, laid proportionally fewer eggs, and had

a shorter oviposition period compared with the wet-season fon11. On rotting

VII

fruit, egg weight increased with fenlale age in wet-season but declined in the

dry-season fonn. Although the dry-season fonll laid larger eggs it still had a

much lower reproductive effort than the wet-season fornl~ indicating that

diapause imposes a substantial cost to subsequent reproduction.

Comparison of the reproductive patterns between the three species (i.e.

wet-season fonns fed on rotting fruit) revealed striking similarities in many

traits, including oviposition pattern, potential fecundity~ reproductive effort and

survival. However, there were substantial differences in allocation st.rategies,

with M. jJerseus partitioning its reproductive effort into nlany srnaller eggs.

Within species there was high degree of egg size v,u·iability. The

significance of this was examined in relation to several offspring fitness

components (larval survival, larval developmental tilne, pupal weight) to

establish if larvae derived from heavier eggs were in any way better than those

derived from lighter eggs when reared on different host plant qualities varying in

leaf toughness and nitrogen content. A number of positive correlations between

egg size and offspring fitness were found when M.'/cale,\;is larvae were reared on

tougher leaves. An adaptive hypothesis is proposed which predicts that the

selective advantage attached to larger eggs rnay represent a dry season survival

strategy to counter adverse conditions - poor host quality or clirnatic

unpredictabili ty.

The dry season strategies and life history traits displayed by M.,/cale~)·is

spp. are discussed in the context of tife history theory. Reference is Inade to the

Southwood-Greenslade habitat templet model which attempts to characterise life

history patterns under two rnajor selection pressures. habitat favourability and

predictability. The three species show SOIne affInity to this schenle with M.

perseus showing many characteristics of an 'r-selected1 type species. The

limitations of the comparative approach in evolutionary studies and irnportance

of confounding variables in making adaptive inferences <.u·e enlphasised.

VIll

Ack110 \v IeelgIllell ts

First, anci forenlost, I thank I11y supervisor Professor Rhondda Jones \vho not only

made available the excellent departtllental facilities v/here this research was carried

out, but also for her scientific wisdonl, expert advice and direction, and infectious

enthusiasnl which guided llie through the years. Above all Rhondda always

showed willingness to help and provided invaluable inspiration during those

frustrating and daunting Illonlents of putting a thesis together. I also thank her for

her meticulous editorial work in reviewing earlier drafts of this thesis.

I aln deeply indebted to Russell Clltnlning (Departillent of Ellvironlnent and

Heritage) and Betsy Jackes (J~l1nes Cook University) for providing expert botanical

assistance and answering I1lany of I1ly bqtanical 4ueries. Russell generollsly

assisted on Inany of tny long and arduous field trips, becaine a reliable field

companion, and showed nle ho\v not to lose a vehicle key in the reInote country of

Cape York Peninsula!

I aIn grateful to I1lany nlenlbers of the Zoology Departnlent and technical

staff for their SUppOl1 and assistance. In particular, I thank Chris Hill for his keen

interest in I1ly work, advice and· suggestions, and for listening to Illy ideas. Bill

Foley and Ms Stephanie White kindly assisted with the plant nitrogen

deterlninations (Ch. 8). Leigh Windsor assisted with the testes preparations of

lnale M. /Jcrseus (Ch. 4). Don Ross al\vays showed willingness to assist with

fixing field equipnlent. Manju Prasad kindly looked after Illy caterpillars and

plants when I was a\vay. Geoff Moore, Richard Rowe and Peter Brovvnell are also

thanked for their advice and knowledge. Zollie Florian generously helped with

photography, specifically plates 6 and 9, and shov/ed Ille ho\v !lor to lose a field

microscope! I should perhaps also thank Illyself for nor losing all nlY teeth whilst

tumbling down a waterfall~

I thank Brian Silllon (Queensland HerbariuIll) for historical inforl1lation on

Guinea grass in Queensland, John Olive of Cairns for providing the blue pupal

lnorphs of M. tern1inus, and Peter Fox of Hervey Bay for SpeCil1lenS of M. !Jer5:CU,,'

and M. tern1illUS. Ted Edwards (CSIRO), Geoff Monteith (Queensland Museulll),

Geoff Holloway (Australian Museun1), Kelvyn Dunn (Griffith University), Terry

IX

Woodger of Townsville, Peter Valentine (Jarnes Cook University) and Fabian

Douglas of WOInbarra provided invaluable distributional infor111ation on .~1yca'e..yi..)~.

GraeIne Wood of Herberto!1 and David Lane of Atherton also provided helpful

inforInation on the distri bu ti on of tro pical satyri nes. l"'erry W oodger and JereIllY

Billington of Townsville are thanked for pleasant COtllpany and assistance in the

field during the latter stages of this work.

I anl ITIOst grateful to the Queensland Forest Service at Cardvv'ell for their

cooperation and pernlission to undertake field work on forestry lands, for

perInission to undertake extensive collection of butterflies, for providing clinlatic

data, and especially for their friendly hospitality and interest during Illy long field

trips.

Finally, I than k III Y pare nts Bob and EIa ine for sup po 11 and encou rage1l1en t

during tiInes of hardship and ill health.

x

Dedication

This thesis is dedicated to my close friend Fabian Douglas:

Amateur entomologist

Ardent explorer

Formidable naturalist

Patient observer

Meticulous artist

Tireless collector

Prodigious taxonomist

Prince of satyrine men

Without his guidance, encouragement and enthusiasm I may never have taken a

serious interest in butterflies.

Xl

Table of contents

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. viiiDedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xList of figures xvList of tables .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. xxList of plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. XXIII

Chapter 1 General introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Life history evolution 21. 2 Trade-offs 41.3 Life history models . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.3.1r-andK-selection 71.3.2 Bet-hedging . . . . . . . . . . . . . . . . . . . . . . . . . . 71.3.3 Demographic models 7

1.4 Habitat templets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5 Studying life histories 14

1.5.1 Comparative methods . . . . . . . . . . . . . . . . . . . . 141.5.2 Constraints on evolution 16

1.6 Aims and organisation of thesis 17

Chapter 2 Natural history of the Australian tropical Satyrinae 202.1 Introduction 202.2 The Australian Satyrinae 21

2.2. 1 Diversity and distribution . . . . . . . . . . . . . . . . .. 212.2.2 Life cycle strategies .. . . . . . . . . . . . . . . . . . .. 24

2.3 Mycalesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 252.3.1 Geographic distribution . . . . . . . . . . . . . . . . . .. 292.3.2 Early stages . . . . . . . . . . . . . . . . . . . . . . . . .. 33

2.3.2.1 Mycalesis perseus .. . . . . . . . . . . . . . .. 342.3.2.2 Mycalesis terminus 362.3.2.3 Mycalesis sirius 372.3.2.4 Observations 43

2.4 Tropical satyrines of northern Queensland . . . . . . . . . . . .. 432.4.1 Distribution and habitat . . . . . . . . . . . . . . . . . .. 432.4.2 Larval host plants 522.4.3 Adult host plants . . . . . . . . . . . . . . . . . . . . . .. 56

2.5 General discussion 58

Chapter 3 Population dynamics . . . . . . . . . . . . . . . . . . . . . . . . .. 633.1 Introduction .......................'........ 633.2 Materials and methods . . . . . . . . . . . . . . . . . . . . . . . .. 65

3.2.1 Study site 653.2.2 Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 653.2.3 Sampling sites 68

xu

3.2.4 Grass moisture content 723.2.5 Transect counts . . . . . . . . . . . . . . . . . . . . . . .. 72

3.3 Results 743.3.1 Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 743.3.2 Grass moisture content 743.3.3 Reliability of transect counts . . . . . . . . . . . . . . .. 773.3.4 Preliminary observations: 1989-90 793.3.5 Seasonal and spatial patterns of abundance: 1991-92. 833.3.6 Diurnal activity . . . . . . . . . . . . . . . . . . . . . . .. 91

3.4 Discussion . . . . . . . . . . . . . . . . . . . . .. 913.4. 1 Relative abundance . . . . . . . . . . . . . . . . . . . . .. 913.4.2 Spatial distribution . . . . . . . . . . . . . . . . . . . . .. 95

Chapter 4 Reproductive seasonality 984.1 Introduction 984.2 Materials and methods . . . . . . . . . . . . . . . . . . . . . . . .. 1004.3 Results 106

4.3.1 Reproductive activity 1064.3.1.1 Mycalesis perseus . . . . . . . . . . . . . . . .. 1064.3.1.2 Mycalesis terminus 1164.3.1.3 Mycalesis sirius 1174.3.1.4 Ypthima arctous . . . . . . . . . . . . . . . . .. 1194.3.1.5 Hypocysta spp .. . . . . . . . . . . . . . . . .. 119

4.3.2 Mating frequency and behaviour 1204.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 125

4.4.1 Opportunistic breeding 1264.4.2 Seasonal breeding 1294.4.3 Continuous breeding . . . . . . . . . . . . . . . . . . . .. 1314.4.4 General discussion . . . . . . . . . . . . . . . . . . . . .. 132

4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 137

Chapter 5 Seasonal polyphenism . . . . . . . . . . . . . . . . . . . . . . . .. 1405.1 Introduction 1405.2 Materials and methods . . . . . . . . . . . . . . . . . . . . . . . .. 1425.3 Results 145

5.3.1 Preliminary observations 1455.3.2 Spot size . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1455.3.3 Body size 153

5.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1535.4.1 Seasonal polyphenism . . . . . . . . . . . . . . . . . . .. 1535.4.2 Body size 157

Chapter 6 Developmental biology .. . . . . . . . . . . . . . .. . . . . . .. 1596.1 Introduction 1596.2 Materials and methods . . . . . . . . . . . . . . . . . . . . . . . .. 161

6.2.1 Temperature. . . . ... . . . . . . . . . . . . . . . . . . .. 1626.2.2 Hostplants . . . . . . . . . . . . . . . . . . . . . . . . . .. 1636.2.3 Statistical analyses . . . . . . . . . . . . . . . . . . . . .. 163

6.3 Results ~ .6.3.1 Egg developmental rate and survival .6.3.2 Larval survival and developmental time .6.3.3 Instar number .6.3.4 Pupal developmental time .6.3.5 Pupal weight and body size .6.3.6 Correlation of life history traits .

6.4 Discussion .6.4.1 Temperature effects .6.4.2 Hostplant effects .6.4.3 Instar number .6.4.4 Sexual size dimorphism and protandry .6.4.5 Size and development: comparison between species ..

Chapter 7 Reproductive biology .7.1 Introduction .7.2 Materials and methods . . . . . . . . . . . . . . . . . . . . . . . . .

7.2.1 The species .7.2.2 M. terminus and M. sirius .7.2.3 M. perseus .7.2.4 Reproductive traits .7.2.5 Statistical analyses .

7.3 Results .7.3.1 Effect of adult diet .7.3.2 Effect of phenotype .7.3.3 Comparison of species .

7.4 Discussion . . . . . .~'. . . . . . . . . . . . . . . . . . . . . . . . . .7.4.1 Effect of adult diet .7.4.2 Effect of phenotype .7.4.3 Comparison of species .7.4.4 General discussion . . . . . . . . . . . . . . . . . . . . . .

Chapter 8 Egg size variation .8.1 Introduction .8.2 Materials and methods .

8.2.1 Larval rearing .8.2.2 Hostplant quality .. 0 ••••••••••••••••••••

8.2.3 Egg volume and larval size .8.2.4 Experimental design and statistical analysis .

8.3 Results .8.3. 1 Egg and larval size . . . . . . . . . . . . . . . . . . . . . .8.3.2 Larval survival .8.3.3 Larval developmental time .8.3.4 Pupal weight .

8.4 Discussion . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . .. .

Cha t 9 G ral dO ·P er ene lSCUSSlon. . . . . . .. . .. . . . . . . . . . . . . . . . . . .

xiii

164164168171173177177183184186189190193

195195197197198199202203203203215218225225228229231

234234236236237238239241241241248248252

260

XIV

References 266APPENDIX 1 # 295APPENDIX 2 # # # 307APPENDIX 3 310APPENDIX 4 # 314

xv

List of figures

Fig. 1.1 The strategy selection system. 10

Fig. 1.2 The Southwood-Greenslade habitat ternplet. . . . . . .. 12

Fig. 2.1 Map of Australia showing diversity of satyrine speciesaccording to phytogeographic regions. 23

Fig. 2.2 Geographic distribution of Mycalesis spp. in Australia. 30

Fig. 2.3 Map of north-eastern Queensland showing geographiczones and sampling sites. 43

Fig. 2.4 Frequency of records of satyrine species within eachgeographic zone. 48

Fig. 2.5 Relative frequency of records of satyrine species for eachvegetation type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 50

Fig. 2.6 Regions of diversity of tropical satyrine butterflies innorthern Queensland. 53

Fig. 2.7 Diurnal frequency distribution of the number of records ofnectar feeding in two adult satyrines, Ypthima arctous andHypocysta adiante. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 57

Fig. 3.1 Map of the study area showing location of sampling sitesA-C and the pilot study site D. 66

Fig. 3.2 Climate at Cardwell showing average monthly rainfall andmean minimum and maximum temperature (source, Bureauof Meteorology 1988a). 67

Fig. 3.3 (a) Mean maximum and minimum temperature and (b)monthly rainfall for Cardwell during the four y~ studyperiod 1989-92 (source, Queensland Forest Service,Cardwell). 75

Fig. 3.4 Seasonal changes in moisture content of Themeda triandraat sites A-C during 1991-92. .... . . . . . . . . . . . . . . . . .. 78

Fig. 3.5 Relationship between absolute population size determinedby mark-release-recapture and relative abundanceexpressed as the mean peak daily abundance as recordedby transect counts for M. tenninus at site A. 80

xvi

Fig. 3.6 Seasonal changes in relative abundance of Mycalesisperseus, M. terminus and M. sirius at site D as determinedby transect counts in 1989-90. 81

Fig. 3.7 Seasonal variation in capture rate of adult female Mycalesisspp. at Cardwell during 1989-90. 82

Fig. 3.8 Seasonal changes in relative abundance of Mycalesisperseus at sites A-C as determined by transect counts in1991-92. 85

Fig. 3.9 Seasonal changes in relative abundance of Mycalesistenninus at sites A-C as determined by transect counts in1991-92. 87

Fig. 3.10 Seasonal changes in relative abundance of Mycalesis siriusat sites A-C as determined by transect counts in 1991-92. .... 88

Fig. 3.11 Diurnal activity patterns of four satyrine species asrecorded by transeCt counts at selected sites: (a) Melanitisleda at two sites in December 1991, (b) Ypthima arctous attwo sites in September 1991, (c) Hypocysta spp. at site Ain September 1991 " 89

Fig. 3.12 Schematic representation of the peak activity periods ofseven lowland tropical satyrines at Cardwell in the late drysea.son. . -. . . . . . . . . . . . . . . . . . . . . . . . . . .. 90

Fig. 4.1 Map of Queensland showing latitudinal zones 1-3 anddistribution of collecting sites. 104

Fig. 4.2 Seasonal changes in the number of eggs, reproductivecondition, rainfall, mean fat content, number ofspermatophores and wing wear for M. perseus at Cardwell. '" 107

Fig. 4.3 Seasonal changes in the number of eggs, reproductivecondition, rainfall, mean fat content, number ofspermatophores and wing wear for M. perseus atTownsville 1990. . 108

Fig. 4.4 Seasonal changes in the number of eggs, reproductivecondition, mean fat content, number of spermatophores andwing wear for M. tenninus at Cardwell. . " 109

Fig. 4.5 Seasonal changes in the number of eggs, reproductivecondition, mean fat content, number of spermatophores andwing wear for M. sirius at Cardwell. . 110

xvii

Fig. 4.6 Comparison of egg-laying rates expressed as the number ofeggs laid per female per day for M. perseus watertreatments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Fig. 4.7 Frequency distribution of the number of spermatophoresfor each wing wear category for (a) M. perseus, (b) M.terminus, (c) M. sirius females collected at Cardwell 1989-90. . 123

Fig. 4.8 Daily and seasonal variation in frequency of copulations in(a,b) M. perseus and (c,d) M. tenninus. . 124

Fig. 5.1 Underside pattern of the left wings of Mycalesis (wet­season form) showing the four eyespots charactersmeasured. 144

Fig. 5.2 Seasonal variation in forewing length and eyespot diameterfor ocelli 2, 5, 7, 11 in adult female Mycalesis perseuscollected over a two-year period at Cardwell 147

Fig. 5.3 Seasonal variation in forewing length and eyespot diameterfor ocelli 2, 5, 7, 11 in adult female Mycalesis terminuscollected over a two-year period at Cardwell 148

Fig. 5.4 Seasonal variation in forewing length and eyespot diameterfor ocelli 2, 5, 7, 11 in adult female Mycalesis siriuscollected over a two-year period at Cardwell. . . . . . . . . . . . . 149

Fig. 6.1 Egg development rates at a range of temperatures for thethree tropical satyrine species: (a) M. perseus, (b) M.tenninus, (c) M. sirius. 165

Fig. 6.2 Egg survival at a range of temperatures for the threeMycalesis species. 167

Fig. 6.3 Survival rates of Mycalesis larvae reared on young growthof two grass species, introduced Panicwn maximwn andnative Themeda triandra, at 25°C and 12: 12 L:D. . 169

Fig. 6.4 Larval development times for males and females of eachbutterfly species reared on Panicum maximum andThemeda triandra at 25°C. 170

Fig. 6.5 Development times for each larval instar for (a) male M.perseus, (b) female M. perseus, (c) male M. terminus, (d)female M. terminus, (e) male M. sirius and (t) female M.sirius reared on Panicum at 25°C and 12:12 L:D. . 172

xviii

Fig. 6.6 Pupal development times for males and females of eachMycalesis species when reared at 25°C. 175

Fig. 6.7 Pupal weights attained for males and females of eachbutterfly species reared on Panicum maximum andThemeda triandra at 25°C. 178

Fig. 6.8 Relationships between pupal weight and length of rightforewing for (a) M. perseus, (b) M. terminus, (c) M.sirius 179

Fig. 6.9 Relationships between larval development time and bodysize attained, expressed as pupal weight, for (a) male M.perseus reared on Panicwn, (b) female M. tenninus rearedon Panicwn, (c) male M. sirius reared on Themeda, (d)female M. sirius reared on Themeda. . . . . . . . . . . . . . . . . . 181

Fig. 6.10 Developmental time (from egg to adult) as a function ofbody size (pupal weight) in Mycalesis reared on Panicumat 25°C and 12L: 12D ~, 182

Fig. 7.1 Climatic data for M. perseus egg-laying field trials, 1991-92, showing daily temperature and rainfall. . 202

Fig. 7.2 Mean age-specific fecundities for M. tenninus and M.sirius on honey solution and rotting fruit. 204

Fig. 7.3 Maximum daily fecundity as a function of pupal weight for(a) M. tenninus and (b) M. sirius 207

Fig. 7.4 Relationships between potential fecundity and pupal weightfor (a) M. perseus, (b) M. tenninus and (c) M. sirius 209

Fig. 7.5 Relative changes in egg output, expressed as a proportionof the potential fecundity, laid in four-day intervals overthe egg-laying period for each species. . 210

Fig. 7.6 Proportion of females surviving against time when egg-laying began for the three species. 211

Fig. 7.7 Relationships between egg weight and female age given astime when egg-laying began for M. terminus and M. siriuson honey solution and rotting fruit. 213

Fig. 7.8 Daily changes in the number of eggs laid and egg weightwith female age for M. perseus dry- and wet-season forms. . .. 216

Fig. 7.9

XIX

Changes in egg colour with female age for M. perseus wet-season form and for M. sirius. . . . . . . . . . . . . . . . . . . . . . 220

Fig. 7.10 Relationship between body size expressed as pupal weightand mean egg weight in M. perseus. 223

Fig. 7.11 Realised fecundity as a function of egg size in Mycalesiswet-season form. 224

Fig. 8.1 Relationships between egg size and egg weight for (a) M.perseus, (b) M. tenninus and (c) M. sirius, and Cd)comparison of the fitted linear regression lines afterlogarithmic transformation. . 242

Fig. 8.2 Relationship between egg size and the size of newlyemerged first instar larva, measured in terms of headcapsule diameter and body length, for (a,b) M. perseus,(c,d) M. terminus and (e,t) M. sirius. . 243

Fig. 8.3 Survival rates of larvae for the three satyrine species withrespect to hostplant treatment. 245·

Fig. 8.4 Egg weights for each larval survival category in relation tohostplant treatment for the three butterfly species: (a) M.perseus, (b) M. terminus, (c) M. sirius. . 247

Fig. 8.5 Relationship between ~initial egg weight and two offspringfitness traits: (a) larval developmental time for M. siriusreared on Themeda, (b) pupal weight for M. perseus rearedon Panicum-soft. 251

Fig. 8.6 Seasonal changes in grass moisture content for Themedatriandra at an open eucalypt forest site near Cardwell,north-eastern Australia, from September 1991 to November1992, and the approximate time when the two seasonalforms of M. perseus are present. 258

xx

List of tables

Table 2.1 Comparison of the taxonomic diversity between thetropical and temperate satyrine faunas of Australia at thespecific and (in parentheses) subspecific levels. . . . . . . . . . .. 22

Table 2.2 Scheme adopted for classification of vegetation typesaccording to tree stratum height and canopy foliage cover,and the number of sites sampled for each vegetation type. .... 47

Table 2.3 Distribution of satyrine butterflies in the four most diverseregions of northern Queensland. . . . . . . . . . . . . . . . . . . .. 54

Table 2.4 Summary of morphological differences between the earlystages of Mycalesis spp. . . . . . . . . . . . . . . . . . . . . . . . .. 60

Table 3.1 Seasonal changes in, and comparison of, maximum dailytemperature at sites A-C as recorded during transect counts1991-92. 76

Table 3.2 Seasonal changes in estimates of absolute IX>pulation sizeof M. tenninus males and females based on a three daymark-release-recapture program during each of fOUf

sampling occasions at site A. . . . . . . . . . . . . . . . . . . . . .. 79

Table 3.3 Seasonal changes in relative abundance for satyrinebutterflies at sites A-C. 84

Table 4.1 Distribution and habitat characteristics in north-easternQueensland of the eight Australian tropical satyrinesstudied. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Table 4.2 Sample sizes collected for each species. . 105

Table 4.3 Reproductive condition of satyrines collected from zones innorthern and central Queensland. . " 111

Table 4.4 Mating frequency based on spermatophore counts forMycalesis females at Cardwell 120

Table 4.5 Mean number of spermatophores for Mycalesis femalesfrom Cardwell in relation to wing wear category. . . . . . . . . . . 122

Table 4.6 Mating frequency based on spermatophore counts for fOUf

satyrines collected from north and central Queensland. 122

xxi

Table 4.7 Incidence of dormancy during the dry season in Australiantropical butterflies. ... . . . . . . . . . . . . . . . . . . . . . . . . . 134

Table 5.1 Correlations between mean spot size (ocellus 7) andambient temperature and photoperiod 2-3 weeks beforecapture for female Mycalesis at Cardwell. . 151

Table 5.2 Effect of developmental temperature on eyespot size in M.terminus (modified fro.m Moore 1985). . . . . . . . . . . . . . . . . 152

Table 5.3 Proportion of wet- and dry-season M. perseus adults rearedfrom eggs laid under field conditions at Townsville duringMarch 1989 and May 1990. 152

Table 6.1 Mean monthly temperatures at selected sites close to theedge of the geographic range of the three satyrine speciesstudied. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16()

Table 6.2 Relationships between egg development rate andtemperature for the satyrine species studied, and thetemperature thresholds and physiological times for eggdevelopment. 166

Table 6.3 Three-way analysis of variance examining effects ofhostplant, butterfly species and sex on larval developmentaltime. . 171

Table 6.4 Larval development time and pupal weight in relation tonumber of larval instars of Mycalesis sirius reared onPanicum at 25°C and 12L:12D 174

Table 6.5 Three-way analysis of variance examining effects ofhostplant, butterfly species and sex on pupal developmentaltime and pupal weight. . 176

Table 6.6 Mean total development time (egg to adult), protandry (thedifference in mean development time between males andfemales), mean pupal weight and sexual size dimorphism(the ratio of female/male pupal weight) for each speciesreared on Panicum at 25 °C and 12L: 12D. . . . . . . . . . . . . . . 176

Table 6.7 Analysis of regression slopes of larval development timeon pupal weight. .. . . . . . . . . 180

Table 6.8 Mean body size, sexual size dimorphism (female forewinglength divided by male forewing length) and carrying sexin copula in ten species of Australian tropical satyrinebutterflies from north-eastern Queensland 192

xxii

Table 7.1 The size of, and the time taken to reach peak egg-laying,given as maximum daily fecundity, and the times taken tolay 50% and 90 % of realised fecundity for each species inrelation to phenotype and adult diet. 205

Table 7.2 Effect of phenotype and adult diet on realised and potentialfecundity, and the proportion of eggs laid in the threesatyrine species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Table 7.3 Effect of phenotype and adult diet on female longevity,expressed as a preoviposition phase and a reproductivephase for each species. . 212

Table 7.4 Effect of phenotype and adult diet on egg weight, realisedreproductive effort and potential reproductive effort foreach Mycalesis species. 214

Table 7.5 Fertility of M. perseus eggs for wet- and dry-season forms. 217

Table 7.6 Reproductive condition of M. perseus wet-season, formfemales when kept at 25°C and I2L: 12D. . 217

Table 7.7 Comparison of reproductive traits for the three Mycalesisspecies (wet-season form on rotting fruit). . 219

Table 7.8 Correlation coefficients between realised fecundity and fivereproductive traits for each species. . . . . . . . . . . . . . . . . . . 222

Table 8.1 Leaf toughness and nitrogen content of Themeda triandraand of three arbitrary leaf classes of Panicwn maximwn. ..... 238

Table 8.2 Experimental design showing the number of eggs and themean and range of egg weights tested on each hostplanttreatment for each butterfly species 240

Table 8.3 Two-way analysis of variance examining effects of larvalsurvival and hostplant quality on egg weight for eachbutterfly species. 246

Table 8.4 Two-way analysis of covariance of egg weight on larvaldevelopmental time for each butterfly species. 249

Table 8.5 Two-way analysis of covariance of egg weight onsubsequent pupal weight for each butterfly species. 250

Table 9.1 Summary of habitat, population, life cycle and life historyattributes for the three Mycalesis species. 263

XXIII

List of IJlates

Plate 1 (a) Adult dingy bush bro\vn M. !Jer.)·eus in coplliation~ (b)Adult male cedar bush brown M. sirius 27

Plate 2 Adult female orange bush bro\vn M. (ernlinus: (a) wingsclosed, (b) wings open 28

Plate 3 Final instar larvae of Mycalesis spp: (a) M. !Jerseus greenmorph, (b) M. !Jcrseus brown tnorph. (c) M. rernlinus. Cd)M. siJ-iLls 39

Plate 4 (a-c) M. !Jerseus pre-pupa. green and brown pupal rnorphs.(d-f) M. sirius pre-pupa, green and brown pupal n1orphs ~ 4()

Plate 5 M. rerlninus pre-pupa (a), and pupal colour Inorphs (b-e) 41

Plate 6 Head capsules of Mycalesis spp: (a-e) M. !Jerseus' instars CII~ IIC IV. V~ (f-j) M. rerrnil111S instars L IL III. IV, V~ (k-o)

M. sirius instars I, II, IlL IV. V 42

Plate 7 (a) Rainforest edge habitat at Site A~ (b) Paperbarkwoodland habitat at Site C 69

Plate 8 Open eucalypt forest habitat at Site B: (a) dry season. (b)

wet se<:'lson 7 1

Plate 9 The three species of Mycale.\'is showing representativeexcunples of the wet-season fon11, inte1l11ediLltc fOlln andthe dry-season fann 146