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TeEperature, hy&ic coaditionq aad hornoaas rlurilg ircubatior can inlluence eEbrroric
g.owth, hatchiDg suc{res, neonatal viability ad morphologr, sex rleterminatio4 ajrd cven adult
physiolog a.nd behavior. ID tlc America[ aligatof (/ligator nbsbsippienslt), relatir€ly low
ircubation tedperatures result i[ &e produdior of female,s, btermediate ircubado! temperatues
rcsult iD both malas ard femalas, ard high incubatior teBperatures producc m6lcs. Joaren et a.l.
(1987) exanircd the ctrect ofincubatiotr tedperature or the post-hatching glowth rate. Comparirg
individuals ion htermediate Eale-birs€d idcubatior tempcratureE malca grow signficadly fasfer
tlajr femalas h both total leogth and body weiglq at the iatermediatc female-biascd iacubation
teBperaturc the fcmales aro hcavie.. This relatiorship bctwe€n incubation tomperature alld gro*th is
seetr 6lso *itlin a serg wit[ fcnalcs ftom 30.6 "C incubation conditioDs growiDg faster thar femdes
fron 31.7 C. O!c.6ll, thc efiect of tempcraturc on groflth i'as such tlat, witlin a limired rote,
individuals fion Ligher incubatior tempcraturcs grow faster thaD do individuals ftom cooler ircubation
temperatue!. Howerc., tiit intcrpretatiotr G coDrplicated by a difrere ial .ru.ot cfiect betweetr
teEpcratuos; thal4 the temp€Iatute that r€$lteal h tte larg€ar aainals also Lad the lo*€st
p€rc€ntage of ruts (delineatcd as the bottoE 10% of tlc bast growing group), while the two erreEe
tchpcraturqs (29.4' a.nd 32.8 C) had ilc highcst iacidelce of ruds.
hcubatio! tempcratue ca! also alfecJ thermoregulatory behaviors that have consequodc€s for
growth. lang (19&7) studied thc elfod of i.ncubatiotr tempclature on body tempelature (Tb) selecrion
in the Sia$ese Gococlile (Oocodtlli sidmensis). Eggs *lle incubated at 28" c' a teDrperature
producing aI feEales, or at 32.t - 35" c, which Foduces all Eales. Individuals fron rtc higher
iocubatior teEperature not ooly grow faster but select a higher Tb.
In all of these studiixs, admals were Loused in social groups ad hencr social htenctions, such
a5 domi&rce a.nd subordi&tioo, Eay traDslate ilto acc€ss to foo4 thereby influercing the rasults.
Similady, thc tcDrpcnturc at wLictr animals are rais€d (versrB thc tomp€raturc at which they werE
iacubatcd as eggs) or possible s€x differcnccs ilr thermoregulalory behavior could have ar effect. To
avoid thesc problcms, reasoiabl€ controls would bc !o rairc 6ubjects at a constant teEperaturc prior to
tesB for thermoregdlation aid to rcar e3ch bdividul in isolation.
It is coBEor laowledge amoog breeders of capti!€ reptiles that ircubation temp€raturc can
iolluencc adult b€havior. Recelt studies with tLe leopard ge.ko (Eublepholit macaran'6) provides sn
excelled example of how tempefthuc duling embryogene.sis affects subs€quent developEeDt. In lhis
specieE Eosdy males are produc€d at futemediatc teEperaturcs (305 - 35. C), whereas only females
arc produced relativcly low ( - zA Q ai at rcar lethd incubatioo tcmperatures (3435. C). In our
studigs we have raised leopard geckos i! isolatioD at a temp€.atuie idtermediate to the i.ncubation
teEpcratrues.
As adults, leopard gectos hare marked scxual dimorphisms i.n morphologf. For c)(ampL, a
secondaty s€x ctraracter is thc spccializ€d secretory porcs loqtod arterior to ttc cloa@. Iu Ealcs, as
well as feEales from high incubation temperatues, thesc pores are opeo, while iD fedales ftom low
hcubatio! temperatures, tley are closed Head size also is s€xually dinorphiq rritl males having
widcr heads tha.u females. However, wit[in each sex, tLe higher the incubatiotr temperaturo, tle wider
the head of thc adult (Crew\ 1988)
It must be approciated that in spccies witl TS4 incubatior tcmperaturc atrd sex co-vary. That
is, in TSD rliflereuces between individuals coutd be duc to the incubatio! te&perature of the cg& the
gonadal sex of the individual$ or both factors combined. If the contribution of each is to be asssssed,
they mtlst be dissociated. Our studies with the leopard gecko Lave entailed removiDg the goaads of
individuals ou hatchiry (to determire tho role ofgonadal horDrones ir poshatal development),
admiDisteritrg honuonc to ircubating eggs (to overide the Ilorma.l effecG of tcmpcranrre), atrd
compariag tie growth ard behavior of individuals of the saee sex but produced at different
temperatures. Figurc 6 indic{te,s that b t[e leopard gecko, both iacubatioa teEpcrature ard the sex of
&e animal havc sigdifica.d effcds on body growtL Further, the presenc€ of the ovaries, but lrot tle
test€S attenuates body gro*tb" It should bc noted tbat tle opposite pattern is found ia the red-sided
garter sDalq itr this species males are staller thar fcmales an