STUDIES ON THE GROWTH OF THE DESERT TORTOISE (TESTUDO SULCATA) IN SUDAN: CHANGES IN MORPHOMETRICS AND BODY WEIGHT FROM HATCHING TO ONE YEAR (O+)

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1 HRPTOLOGICAL JOURNAL, Vol. I, pp (1988) 280 STUDIS ON TH GROWTH OF TH DSRT TORTOIS (TSTUDO SULCATA) IN SUDAN: CHANGS IN MORPHOMTRICS AND BODY WIGHT FROM HATCHING TO ON YAR (O+) z. N. MAHMOUD AND D. A. L NAIM Deparrmenr of Zoology, Facu/ry of Science, Universil)' of Kharroum. Kharroum. Sudan. (Accepred // ) ABSTRACT Changes in morphomerics and body weigh during growh was deduced from observaions of individual Tesudo sulcaa of known age. A srong posiive correlaion was found o exis beween plasron widh (r = ), carapace lengh (r = 0.94), carapace widh (r = 0.94), body weigh (r = 0.99) and plasron lengh. Changes in morphomerics and body weigh during growh in heir firs year of life has been invesigaed. The oroises increased in size a a rae of x -3mm day-1 (plasron lengh), x J0-3mm day-1 (plasron widh), x J0-3mm day-1 (carapace lengh), x J0-3mm day-i (carapace widh) and x J0-3g day-i (body weigh). The values of he inercep, regression coefficien and insananeous growh rae (K) were calculaed for T. sulcaa and from similar growh daa in he lieraure. Their relaion o morphological changes in oroises and urles have been discussed. INTRODUCTION Curren ideas on repiles life hisories sugges ha individuals exhibi a series of growh raes during heir lives as a funcion of he source of energy and coss of growh, aciviy and reproducion (Gibbons, 1968; Wilbur, 1975; Andrews, 1982). This disconinuiy in he rae of growh and he endangered saus of many repilian species make idenificaion of growh raes an imporan area of research, especially in he early sages of he life hisory. Alhough growh, morphomerics and he relaive growh of a par in relaion o ha of he enire organism in many chelonian species have been sudied in deail (see Cagle, 19; Gibbons and Semlisch, 1982; Meek, 1982; Long, 1984; Mahmoud, l Naeem and Hamad, 1986), early growh has received Jess aenion and none of he published work (King, 1964 on Tesudo gracea, Blackwell, 1968 on Kinixys homeana, Cloudsley-Thompson, 1970 on T. sulcaa, Tryon. and Hulsey, 1977 on Clemmys muhlenebergi, Bienefield, 1979 on Hydromedusa ecifera, Davis, 1979 on Geochelene carbonaria, Peers and Finne, 1979 on Geochelone giganica, Brown, Marvey and Wilkins, 1982 on relmohelys imbricaa and Inskeep, 1984 on Cuora ambainensis) has rigorously been quanified. From hese daa, relaive growh raes were calculaed and correlaions were esimaed by Linear regression. This paper describe some aspecs of he early growh (O+) in Tesudo sulcaa from haching o one year afer haching. MATRIAL AND MTHODS MAINTNANC Newly hached T. sulcaa (I 6 from he same cluch) were kep in an enclosure ( 1.3 x 1.3 x 2m) wired on he op and back wih a shu of glass for viewing on he fron. The enclosure conained a shallow concree pool (0.3 x 0.3m). Food was offered every oher day and readily acceped. I consised of Medicago saliva and Vicus bengalensis. During February, 1987 he oroises were unable o feed. This was probably due o a bacerial infecion of he mouh. Treamen consised of a daily dose of I ml of Rivocllin (Rivopharm, Swizerland) adminisered orally for one week. The mouh condiion responded well, and he animals hen began o gain weigh rapidly once more. MASURMNTS ach individual was marked in a coded paern by filling he marginal scue o produce sligh noches in he bones. To aid recogniion, dark marker pain was placed on he noched marginal scue and renewed mosly a he ime of measuremen. Records for each individual were kep. These consised of age, weigh in g, (measured wih a Meler balance sensiive o 0. I g), and four linear measuremens: plasron lengh (PL) (greaes lengh measured a he midline), plasron widh (PW) (maximum widh along he midline) carapace lengh (CL) (greaes lengh measured along he midline) and carapace widh (CW) (maximum widh along he midline). These measuremens were made wih a calibraed ape, accurae o I mm. STASTISTICAL ANALYSIS Regression analysis of plasron lengh as well as oher morphomeric measuremens, and body weigh were carried ou in accordance wih he following equaion. X =a+ by where: Y is he plasron lengh in mm; a = he inercep and b he regression coefficien of he morphomeric measuremen in mm or body weigh in g.

2 GROWTH OF TSTUD O SULCATA 28 1 Relaive growh raes, measured as rae of increase per day, were calculaed from he formula (Brody, 1945). where: K = LnX i - LnX 0 i - o K, is he insananeous relaive growh rae X 0 and Xi are he morphomeric measuremens or body weigh a he beginning and end of he age inerval 0 o ; Ln, is he base of he naural logarihm. RSULTS growh in T. sulcaa was esed by ploing he wo parameers agains each oher. The lineariy of he poins (Fig. 1) sugges eiher parameer can be used o assess growh. Growh in plasron widh and carapace widh was invesigaed in relaion o plasron lengh. The lineariy of he poins and he regression analysis show a high correlaion beween PW, CL, CW and he lenghening of he plasron (Fig. 1; Table 1) where 88, 88 and 94 per cen of he poins respecively, were accouned for. RLATIV GROWTH The reliabiliy of using eiher plasron lengh or carapace lengh as crieria for he measuremen of F'og.2 F'll "' Q so 20...,.., 0 ro m Plasron lh( mm) Fig. Relaionship beween, plasron widh ( -- ), carapace lengh (<D--<D), carapace widh (o--o), body weigh (0--0) and plasron lengh in O+ T. sulcaa '-. J o..._ _... o 0 1 1,_...,.AAy19e c MorhS > Apri/May 1987 Fig. 2 Insananeous relaive growh rae of plasron lengh ( +--+ ), plasron widh ( -- ), carapace lengh ( o--o ), carapace widh (@--@), and body weigh ( ) beween when firs measured in June, 1986 and las measured in May, 1987 as a funcion of age in O+ T. su/caa. Parameer Inercep Regression Correlaion coefficien coefficien r2 Carapace lengh Carapace widh Plasron widh Body weigh TABL 1: Resuls of he regression analysis of some morphoqieric measuremens (mm) and of body weigh (g) on plasron lengh (mm) of T. su/caa.

3 282 Z. N. MAHMOUD AND D. A. L NAIM The regression beween plasron lengh and body weigh (Fig. I) expressed by he equaion: W = x PL indicaes ha body weigh increased relaively faser han plasron lengh, because he regression coefficien is greaer han I (Table I). The correlaion is very highly significan and 98 per cen of he poins are accouned for. The plo of he monhly insananeous relaive growh raes (Fig. 2) shows ha carapace lengh and widh had a greaer overall relaive rae of growh han plasron lengh and widh. However, he inconsisency in his rend hroughou he year is probably due o he formaion of a carapace of he same shape. Fig aj 1.6 ' F1-;i 4 90 ISO '0 c.!< e Vi ;;, 80 :6. 70 > c. g. 19.!< ' 3 I I.l<J>el s Age( Monhs i Mai 1967 Fig. 4 Relaionship beween he growh in plasron lengh (o--o), body weigh ( -- ) and ime (monhs). The growh modes are represened by he regression lines a A<je( MonlhS ) >.Jne1986 M.l.y 1987 Fig. 3 Relaionship beween plasron lengh (o- -o), body weigh ( -- ) of O+ T. sulcaa and ime in monhs during June 1986 and May ABSOLUT GROWTH When he mean plasron lengh and mean body I 20 0 weigh were ploed agains age on a linear scale, a sigmoid growh paern was obained (Fig. 3). The plo of he logarihmic value of he mean plasron lengh and he mean body weigh agains age, sraighen he curve for plasron lengh (Fig. 4). A separae regression line has o be calculaed for each of he hree growh modes obained for body weigh (Fig. 4 and Table 2). The poins of inersecion of he regression lines were observed o lie beween days 84 and 282 afer haching. The hree regression were highly significan (P<0.01) and mos of he poins were accouned for by he hree lines. Parameer Inercep Regression Correlaion coefficien coefficien r2 Plasron lengh Body weigh Firs growh mode Second growh mode Third growh mode I TABL 2: Resuls of regression analysis for he relaionship beween plasron lengh (X, log mm) and body weigh (X, log g) wih age (Y, monhs) in T. sulcaa. The regression following he equaion. Y =a + b logx, where a and b are consans.

GROWTH OF TSTUDO SULCA TA 283 Species No. of Duraion Body Plasron Plasron Carapace Carapace Reference animals o - I weigh lengh widh lengh widh in days g.

4 GROWTH OF TSTUDO SULCA TA 283 Species No. of Duraion Body Plasron Plasron Carapace Carapace Reference animals o - I weigh lengh widh lengh widh in days g. day- I mm day- 1 mm day- 1 mm day- 1 mm day Geoche/one carbonaria Davis, 1979 Geoche/one giganica Peers and Fine, 1979 Kinixys homeana Blackwell, 1968 Tesudo gracea King, 1964 T. su/caa Cloudsley-Thompson, 1970 T. su/cma Presen work C/emmys muhlenbergii Tryon and Hulsey, 1977 Hydromedusa ecifera Benefi eld, 1977 remochelys imbricaa Brown e al., 1986 Curo amboinenisis Inskeep, 1984 TABL 3: Calculaed Insananeous growh rae (k-value) for some chelonians (presen work and lieraure) Growh in he weigh of hach ling T. su/caa per uni ime was characerised by an iniial fas growing period a a rae of x -Jg day-1 unil abou Augus, followed by a slow growing rae of 1. x -Jg day-1 unil abou February and a fas growing rae of 5.13 x -Jg day-1 by he ime when he animals are one year old (Table 2 and 3). The growh in plasron lengh followed he same rend and during hese period a rae of 1.52 x -3mm day-1, 0.65 x -3mm day-1 and 1.85 x -Jmm day- 1 was compued. DISCUSSION During he growh of newly hached T. sulcaa a srong posiive correlaion was fo und beween plasron lengh and oher morphomeric measuremens (Table I). Similar fi ndings have been repored beween plasron lengh and carapace lengh in young hach ling Plaemys playcephala (r = 0.99) by rns and Lovich ( 1986) and in adul of Gopherus agassizi ( r = 0.99) by Medica, Bury and Turner (1975). They have also been calculaed from he daa of Peers and Finne ( 1979) in one year old G. giganica (r = 0.93). Plasron lengh can herefore be used as he independan variable in relaive and absolue growh sudies, due o is relaively consan rae of growh. rns ( 1977) and rns and Lovich ( 1986) saed ha sraigh line carapace measuremen includes much hidden growh masked in is curvaure. Mahemaical models based on plasron lengh could be misleading if differences in plasron lengh beween males and females exis. Alhough plasron lengh dimorphism has been demonsraed in several chelonian species (Berry and Shine, 1980; Branch, 1984), he cleares sex discriminaion fu ncions (ail lengh and anal region measuremens) failed o disinguish he sex of O+ T. sulcaa (Mahmoud and Musafa, 1987). In he presen sudy all of T. sulcaa examined were small in size (under 6mm plasron lengh) and can only safely be classified as juveniles. Therefore, he plasron lengh is clearly a useful measuremen for describing he growh of O+ T. sulcaa. The presen sudy showed ha in T. sulcaa he body weigh increases relaively faser han plasron lengh (b >I, Table!). The calculaed regression coefficien values showed ha he o+ old oroises end o increase more in weigh han in lengh when compared wih O+ old urles (Table 4). This migh be due o relaively faser growh of oroises as ha hey become dome-shaped wih increase in size, while urles ends o remain fl a. Similar observaions have Species Inercep Regression Correlaion Reference coefficien coefficien Toroises: Geoche/one carbonaria Geoche/one giganica T. sulcaa Davis, 1979 Peers and Finne, 1979 Presen work Turles: Hydromadusa ecifera C/emmys muhlenbergii Cure ambo/mensis Benefield, 1977 Tryon and Hulsey, 1977 Inskeep, 1984 TABL 4: Regression analysis of carapace lengh (mm) and body weigh (g) describing he early growh in some chelonians.

5 284 Z. N. MAHMOUD AND D. A. L NAIM been repored in. imbricaa by Brown e al. ( 1982). Mosiman ( 1958) and Long ( 1984) repored ha he lengh of he fla sof-shell urles had greaer inercep values as opposed o oher, more domed species. The same opinion hold rue when he inercep value of T. sulcaa (presen sudy) and calculaed values for oroises and urles (lieraure) are compared (Table 4). In T. sulcaa lae summer and early winer accoun for he lower K-values during mid-augus o mid J anuary. Medica e al. (1975) found ha G. agasszi grew mos rapidly during he spring (mid-april) and early summer (firs week of July). However, he discrepancy of he K-value (presen work and lieraure) is due o difference in he species, heir zoo geography, he duraion of he sudy and number of animals involved (Table 3). Addiional long erm growh daa are required o verify wheher he fl ucuaion in K-value is due o seasonaliy and/or some physiological facors ha need o be invesigaed. To cas ligh on hese problems, records for he 1986 hachling will coninue and he 1987 hachling are now sudied in erms of he impac of environmenal facors and food qualiy on growh of T. sulcaa. ACKNOWLDGMNT Thanks are due o Prof. J. L. Cloudsley-Thompson for his ineres in our sudy and for reviewing he manuscrip. RFRNCS Andrews, R. M. (1982). Paerns of growh in repiles. In Biology of he Rep1ilia Vol. 1, (d) C. Gans. Academic Press. New York. Benefield, J. ( 1979). Haching he Argenine snake-necked urle Hydromedusa ecifera a San Anonio Zoo. Inernaional Zoo Yearbook 19, Berry, J. F., Shine, R. (1980). Sexual size dimorphism and sexual selecion in Turles (Order Tesudines). Oecologia (Berl) 44, Blackwell, K. ( 1968). Some observaions on he haching and growh of he African oroise Kinixys homeans. Briish Journal of Herpeology 4, Branch, W. R. (1984). Preliminary observaions on he ecology of he angulae oroise ( Chersina angulaa) in he asern Cape Province, Souh Africa. Amphibia Repilia 5, Brody, S. (1945). Bioenergeics and growh. New York, Reinhold. Brown, R. A., Harvey, G. C. M. and Wilkins, L. A. (1982). Growh of Jamaican Hawksbill urles (remochelys imbricaa) reared in capaiviy. Briish Journal of Herpeology 6, Cagle, F. R. (l 9). The life hisory of he slider urle, Pseudemys scrip/a (Molbrook). cological Monographs 20, Cloudsley-Thompson, J. L. ( 1970). On he biology of deser oroise Tes1udo sulca1n in Sudan.Journal of. Zoology London, 160, Davis, S. ( 1979). Husbandry and breeding of he red-fooed oroise Geochelone carbonaria a he Naional Zoological Park, Washingon, ln1erna1ional Zoo Yearbook 19, -53. rns, C. M. (1977). Biological noes on he bog urles, Clemmys muhlenbergic HerpelOlogica 33, rns, C. H. and Lovich,.I.. ( 1986). Morphomery in he chelid urle, Plaemys playcephala. The Herpeological Journal I, Gibbons, J. W. (1976). Aging phemomena in repiles. xperimenal Aging Research d. by M. F. bas, B.. lefheriou and P. K. Klias pp AR Inc. Bar Harbor, Maine. Gibbons,.I. W. and Semlisch. R. D. ( 1982). Survivorship and longeviy of a long-lived verebrae species: How long do urles live: Journal of Animal cology 51, Inskeep, R. (1984). A noe in he capive breeding ofihe box urle Curo amboinensis (Daudin, 1802). Brilish.Journal of Herpeology 6, King, J. M. B. (1964). Rearing young Medierranean spurhighed oroises (Tesludo gracea). Briish.Journal of Herpeology 3, Long, R. D. (1984). lnerspecific comparisons of growh relaionships in chelonians. Briish Journal of HerpelOlogy 6, Mahmoud, Z. N., l Naiem, D. A. and Hamad, D. M. (1986). Weigh and measuremen daa on he grooved oroise Tesudo sulcaa (Miller) in capiviy. Herpeological Journal I, 7-1. Mahmoud, Z. N. and Musafa, S.. (1987). Sexual size dimorphism, sexual selecion and sex behaviour in Tesudo sulcaa. In preparaion. Medica, P. A., Bury, R. B. and Turner, F. B. ( 1975). Growh of he deser oroise (Gopherus agassizi) in Nevada, Copeia 1975, Meek, R. ( 1982). Allomery in chelonians. Briish Journal of Herpeology 6, Mosiman, J.. (1958). An analysis of allomery in chelonian shell. Revue Canadienne de Biologie 17, Peers, V. W. and Finne,. P. ( 1979). Firs breeding of he Aldabra oroise Geochelone giganica a cap iviy a Sydney Zoo. Inernaional Zoo. Yearbook 19, Tryon, B. W. and Hulsey, T. G. (1977). Breeding and rearing he bog urle Clemmys muhlenbergii a he For Worh Zoo. Inernaional Zoo Yearbook l 7, Wilbur, H. M. (1975). A growh model for he urle Chrysemys pica Copeia 1975,

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