populations (Barbault, 1975, 1981; Van Deven- der, 1978; Lernos-Espinal and Ballinger, 1995 a). Sceloporus grammicus is a small (54 to 72 mm SVL) viviparous lizard, distributed throughout most of frorn sea leve1 to high mountain conditions. Along its range this exhibits extensive varia- tion in meristic and morphometric characteristics, as well as in heterozygosity values and genic polymor- phism (Hall and Selander, 1973; Sites, 1980). Sceloporus grammicus is in the auturnn breeding viviparous liz- ard group (Guillette and Casas-Andreu, 1980), with one litter per year and parturition occurring during April, May, or June (Ortega and Barbault, 1984). However, although S. grammicus is an abundant and widespread lizard (Smith, 1939), there are relatively few studies concerning this . Most of these studies are of a taxonomic nature (Hall, 1973; White, 1978; Sites 1980,1983) or concern reproduction (Axtell and Axtell, 1970; Guillette and Casas-Andreu, 1980, 1981; Guillette and Sullivan, 1981; Reed and Cites, 1995). There are relatively few works dealing with ecological aspects of this lizard (Lemos-Espinal and Ballinger 1992, 1995b), and only one on the growth patterns (Lemos-Espina1 and Ballinger, 1995a). The study site, La Michilía Biosphere Reserve, is in southern , México, between 104"201 and 104"07'W and 23"201 and 23"301N. The vegetation is typically an oak-pine forest but highly diversified, with 207 plant species, including 18 species of Qucr- cus, and 10 species of Pinus (Martínez and Saldíwr, 1978). The climate exhibits a mean amual tempera- ture range between 17.4 C and 20.7 C and a mean annual precipitation of 567 mm, with most of the rain concentrated in the summer. At La Michilía, summer is hurnid and hot and winter is cold and dry (Martí- nez and Saldívar, 1978). A study plot of 50 X 1 000 m was marked with stakes every 10 m, and censuses were made over four lournal o Heqietology Vol. 33 No. 1 pp. 123-126 1999 years during September and December 1979, March, Copyri&t 1999 %a& for tíhe ~tudyof ~rn~hibiansand May, and Septernber 1980, each month of 1981, and March, May, and September of 1982. Each of these 20 censuses Iasted 15 d. Each day, the transect was Growth of Sceloporus grammicus in La walked by three persons for 4 to 7 h in search for Michilía Biosphere Reserve, Mexico . For each lizard we observed we recorded the date, the hour, its sex, its location in relation to the ALFREDOORTEGA-RUBIO,',-' GONZALO HALFFTER,' ROB- nearest stake, and then captured the lizard by hand. ERT BARBAULT,'ARADIT CASTEII.ANOS,%ND FEDERICO We recorded the following data; SVL and tail length SALINAS~'instituto de Ecología, Apdo. Postal No. 63, Xal- to the nearest 0.1 mm with a caliper and body mass aya, Veracwz 91000, México; >EcoleNormale Superieure, to the nearest 0.1 g with a Pesola spring balance. Cap- 46 Rue D'Ulm, Paris Cedex 05, Frunce; Tentro de Inves- tured individuals were marked individually both by tigaciones Biológicas del Noroeste, Apdo. Postal No. 128, La toe clipping and by paint code (Tinkle, 1967).The age Paz, 23000, Baja California Sur, México classes were determined through mark-recapture methods (Ortega, 1986). Juveniles were individuals The pattern of growth 1s a key aspect in the life 13mo of age, subadults were individuals between 3 history of any species (Andrews, 1982; Lemos-Espina1 and 5 mo, adults 1 were individuals reaching sexual and Ballinger, 1995a). Growth rates determine, among maturity from 5 to 12 mo, and Adults 11 were indi- other imyortant attributes, the length and age reached vidual~older than one year. at sexual maturity and maximum body size (Barbault, Using the size differences between capture and re- 1975; Andrews, 1976; Van Devender, 1978; Kaufmann, capture of a particular individual, the Instantaneous 1981; Parker, 1994; Smith and Ballinger, 1994). Body Growth Rate (IGR) was calculated using the formula size, in many reptiles, determines crucial reproductive of Barbault (1973): final SVL - initial SVLInumber of characteristics such as reproductive effort and clutch days between captures. Only individuals with recap- size (Barbault, 1974; 1981), as well as competitive suc- ture intervals <90 and >30 d were used in parameter cess for space and food (Fox, 1983; Tokarz, 1985). analyses. Analysis of covariance (ANCOVA; Cokal and Thus, the study of growth patterns can help to un- Rohlf, 1969) with initial SVL as the covariate and sea- derstand the structure, dynamics, and dernography of son, size class, and cex as factors was used to analyze 126 SHORTER COMMUNICATIONS

body weights of the Mexican high elevation lizard CITES, J. W., JR. 1980. Chromosome allozyme, and mor- Sceloporus grammicus microlepidotus. J. Herpetol. 15: phometric variation in three cytotypes of the Sce- 366-371. loporus grammicus complex. Unpubl. Ph.D. Diss., , AND P. W. SULLIVAN.1985. The reproductive A &M Univ., College Station. and fat body cycles of the lizard Sceloporus formo- . 1983. Chromosome evolution in the iguanid sus. J. Herpetol. 19:474480. lizard Sceloporus grammicus. 1. Chromosome poly- HALL,W. P. 1973. Comparative population cytogenet- morphisms. Evolution 36:38-53. ics, speciation and evolution of the iguanid lizard SMITH,H. M. 1939. The Mexican and Central Ameri- genus Sceloporus. Unpubl. Ph.D. Diss., Harvard can lizards of the genus Sceloporus. Field Mus. Nat. Univ., Cambridge, Massachusetts. Hist., Zool. Ser. 26:l-397. , AND R. K. SELANDER.1973. Hybridazation of SMITH,C. R. 1996. Annual life-history variation in the kariotypicaliy differentiated populations in the striped plateau lizard, Sceloporus virgatus. Can. J. Sceloporus grammicus complex (Iguanidae). Evolu- ZOO~.74:2025-2030. tion 27:22&242. , AND R. E. BALLINGER.1994. Temporal and KAUFMANN,K. W. 1981. Fitting and using growth spatial variation in individual growth in the spiny curves. Oecologia 49:293-299. lizard, Sceluporus jarrwi. Copeia 1994:1007-1013. LEMOS-ESPINAL,J. A., AND R. E. BALLINGER.1992. Ob- SOKAL,B. R., AND F. J. ROHLF.1969. Biometry. 2nd Ed. servations on the tolerance to freezing by the liz- Freeman Publ. Co., San Francisco, California. ard, Sceloporus grammicus, from Iztaccihuatl volca- SOULE,M. 1966. Trends in the insular radiation of a no, México. Herpetol. Rev. 23:8-9. lizard. Amer. Natur. 100:47-64. , AND --. 1995 a. Ecology of growth of the TANNER,W. W., AND J. H. HOPKIN.1972. Ecology of high altitude lizard Sceloporus grammicus on the Sceluporus occidentalis longipes baird and Uta stans- Eastern slope of Iztaccihuatl volcano, Puebla, Méx- buriana Baird and Cirard on rainier mesa, Nevada ico. Trans. Nebraska Acad. Sci. 22:77-85. test site range county, Nevada. Brigham Young , AND -. 1995 b. Comparative thermal Univ. Sci. Bull. Biol. Ser. Vol. XV:1-30. ecology of tlie high-altitude lizard Sceloporus granl- TINKLE,D. W. 1967. The life and demography of the micus on tho eastern slope of the Iztaccihuatl vol- side-blotched lizard, Uta stansburiana. Misc. Publ. cano, Puebla, México. Can. J. Zool. 73:2184-2191. Mus. Zool. Univ. Michigan 132:l-182. LICI-~T,P. 1974. llesponse of Anolis lizards to food sup- TOKARZ,R. R. 1985. Body size as a factor determining plementation in nature. Copeia 1974:215-221. dominance in stage agonistic encounters between MART~NEZ,E. AND M. SALDIVAR.1978. Unidades de male brown anoles (Anolis sagrei). Anim. Behav. 33: vegetación en la Reserva de la Biósfera de La Mich- 746-758. ilía en el Estado de Durango. Publicación No. 4 del TRIVERS,R. L. 1976. Sexual selection and resource-ac- Instituto de Ecología. cruing abilities in Anolis garmani. Evolution 30:253- MAUTZ,W. J. 1979. The metabolism of reclusive liz- 269. ards, the Xantusiidae. Copeia 1979:577-589. TURNER,F. B., AND C. s. CIST.1970. Observations of ORTEGA,A. 1986. Dinámica y estrategias demográficas lizards and tree frogs in an irradiated Puerto Rican de dos poblaciones de iguanidos simpatricos en la Forest. In H. T. Odum and R. F. Pigeon (eds.), A reserva de la biosfera la Michilía. Unpubl. Ph.D. Tropical Rain Forest, pp. E25-E49. US Atomic En- Diss., Instituto Politécnico Nacional. México. ergy Comm., Springfield. Virginia. , AND R. BARBAULT.1984. Reproductive cycies VANDEVENDER, W. R. 1978. Crowth ecology of a trop- in the mesquite lizard Sceloporus grammicus. J. Her- ical lizard, Basiliscus basiliscus basiliscus. Ecology petol. 18:168-175. 59:1031-1038. WEBB,C. J. W., H. MESSEL,J. CRAWFORD,AND M. J. , AND L. HERNÁNDEZ.1983. Abundancia rela- tiva de insectos en un medio estacional: su influen- YERBURY.1978. Crowth rates of Crocodylus porosus cia en la historia de vidad de dos iguánidos sim- from Arnhem Land, Northern Australia. Austr. pátricos. Folia Entomológica. No. 55:129-144. Wildl. Res. 5:385-399. PARKER,W. S. 1994. Demography of the fence lizard, WHITE,M. J. D. 1978. Modes of Speciation. W. H. Free- Sceloporus uildulatus, in northern Mississippi. Cop- man and Co., San Francisco. California. eia 1994:136-152. WILBUR,H. M. 1975. A growth model for the turtle Chrysemys picta. Copeia 1975:337-343. REED,K. M.. AND T. W. SITES.1. R. 1995. Female fecun- dity in a hybrid zone beiween two chromosome Accepted: 30 Ceptember 1998. races of the Sceloporus xrammicus complex (Sauria, ~hr~nosomatidaé).~vo¡ution 49:61-69 RUBY,D. E. 1977. Winter activity in Yarrow's , Scelop?orus jarrwi. Herpetologica 33:322-333. . 1978. Seasonal changes in the territorial be- havior of the iguanid lizard Sceloporus jarrwi. Cop- eia 1978:430-438. SCHOENER,T. iV. 1970. Size pattems in West Indian Amlis lizards, 11. Correlations with the sizes of par- ticular sympatric species-displacement and di- vergence. Amer. Natur. 104:155-174. , AND A. SCHOENER.1978. Estimating and in- terpreting body-size growth in some Anolis liz- ards. C0pei.i 1978:390-405. 124 SHORTER COMMUNICATIONS the influence of body size on IGR. Adjusted means were tested with the Student-Newman-Keuls (SNK) Post Hoc Test (Sokal and Rohlf, 1969). IGR data were adjusted to the differential equations of the curves and models most frequently used to de- scribe animal growth. For this purpose, we calculated the size incre,ase per day percentage, alco called Rel- ative Growth Rate (RGR), using the method of Kauf- mann (1981): in final SVL - in initial SVL/number of days between captures. RGR values were plotted against the geometric means (S) of the individual body size, S (S = (S,.S,)K). If the plotted data yields a straight line using semi- log paper, a Gompertz curve can be used to describe the observed data pattern (Kaufmann, 1981). If a straight line is obtained using logarithmic paper, then a potency curve must be used and, if a straight line is obtained with linear graph paper, then the logistic or the Bertalanffy curves can be used (Bertalanffy, 1957, 1960; Kaufmann, 1981). It is possible to calculate the linear regression for the plotted data, and calcu- lating the origin and the slope establishes the differ- ential equation that defines the pattern observed. A total of 142 recaptures on 106 individuals were made during the four years of study. Individual data are grouped by season, sex, and age class in Table 1. IGR diminished drastically as the organisms grew. Ju- veniles grew much more quickly than subadults and adults (F.,,,,= 1544.26; P < 0.001), subadults grew more quickly than adults, and adults 1 grew faster than adults II (al1 P < 0.05, SNK Post Hoc Test). In the younger age classes, adult males grew more quick- ly than females (F,,,,,, = 19.27; P < 0.01). Among the older classes, lGRs were practically equal for males and females. lncluding juveniles and subadults in the analysis, S. gruniiiricus grew faster during spring and summer (F,,,,,= 457.57; P < 0.001), because juvenile hatchling occurs at the end of the spring. However, taking into account only adults 1, where it is possible to make comparisons among seasons, we found a sig- nificantly quicker growth during summer and autumn (F,,, = 196.54; P < 0.001) as compared with the adult 1 growth durong the spring and the winter (P < 0.05; SNK Post Hoc Tests). For adults 11, we observed sig- nificantly quicker growth during summer and autumn (F,,,,, = 34.96; P i0.001) as compared with the spring, with the winter having the lowest values (P < 0.05; SNK Post Hoc Tests). a 2222 The RGR data and the geometric meaii of the in- m oooo dividual body size for each individual recaptured were plotted on seinilog, log, and linear paper. There was a good fit both with the semilog and linear plots. We found the best fit for the linear plot, where Y = 0.4046 x -0.i30698; r = 0.81; P < 0.05. Thus, the Ber- talanffy growtli ciirve best fits the S. grcirriniicus growth data. I'reviously, it liad bt,eii reported that for small and short-livcd lizards, the bcst model fitted is the logistic one (l'inklc 1'467; Uunhani, 1978; Aiidrews, 1982). The growth pattcrns of larger reptiles with longer life spans usually follow the Bertalanffy mcidel (Wilbur, 1975; Webb et al., 1978; Chabreck and Joanen, 1979). tiowever, the growth pattern of S. gniriiniicus at La Michilía follows the Bertalanffy model, i.e., maximum growth rates are rrachcd in the youiiger agr classcs and thest, ratcs ciecrease as the size increases. Our re- SHORTER COMMUNICATIONS sults are ccjnsistent with those obtained for many 0th- months, but the reninant matured at 17 mo. However, er reptiles (Turner and Gist, 1970; Trivers, 1976; most temperate anti montane lizards mature at nine Schoener and Schoener, 1978; Van Devender, 1978), in- months to two years (Barbault, 1975). 'luding other populations of grammicus(Lemos-Es- ~cknow~edgmcnis,.-Thiswork was supported jointly pina1 and Ballinger, 1995a). by the Consejo Nacional de Ciencia y Tecnología 'here are many interde~endent that (CONACyT), the lristituto de Ecologja, and The Gen- mine growth rates including food and water avail- tro de investigaciones Biológicas del Noroeste (CIB- ability (Andrews, 1982; Smith and Ballinger, 1994; NOR), of México; by the Normale Cupcrieure, Cmitk 1996), phenological phase of the individual the Council National de la Ccientifique (Tanner and Hopkin, 1972), inter- and intraspecific (CNRS) of France and by the MAB pro- competition (Soule, 1966; Schoener, 197'4, predation gram, We would like to thank to D~, Niewia- (Mautz, 19791, and for lizards, tail breakage (Ballinger rowski and one anonymous reviewer for their kind and Tinkle, 1979). lndividual growth varies with avail- helpful suggestions, which highly improved an able energy; thus many lizard species exhibit quicker version of the manuscript, D~.~lli~ ~l~~i~~ for growth rates during the season of higher prey avai'- editing the English text, and to Lolita Vázquez who ability (Smith and Ballinger, 1994; Smith, 1996) or tyFd the manuscript. when they have access to supplementary food (Licht, 1974). Ll 1 ERATURE CI'TED At the La Michilía Biosphere Reserve, the prey of S. ANDKEWS,R. M. 1976. Growth rate in island lizards. grammicus are most abundant (both in number and 1976:477-482, biomass) from June to October (Ortega and Hernán- -. 1982. Patterns of growth in reptiles. In C. Gans dez, 1983). Growth rates of S. grarnmicus are highest and F. Pough (eds.), Biology of Reptilia, Vol. 13, during this same period, as we would predict, based pp. 273-319. Academic Press. New York. on the well established link between prey ahundance A, C., AND W, AXTELL.1970, Hibernacula and liziird growth (Smith and Ballinger, 1994; Smith, birth and young of Sce[rJporusgrarnmicus disparilis 1996). Most of the S. grammicus hatchlings are born (Iguanidae). Southwest. Natur. 14:363-366. during the second of Ma~and the first part BALLINCEX,R. E, 1973, Comparative demography of June (Ortega and Barbault, 1984). two viviparous iguanid lizards (Sceloporus jarrovi The effect of seasonality on lizard growth 1s not and ~~~l~~~~~~poinsetti). ~~~l~~~ 54:262-238. well documented. Our data indicate that the adult -, AND D. W. TINKI.E1979. On the cost of tail classes grew in summer autumn (Table '1. regeneration to body growth in lizards. J. Herpetol. Growth rates were lower during spring and lowest 13:374-375, durinl; the winter (F,n= 20.I9; P < Newborn BARI)AULT,R. 1973, Structure et dinamique d' un peu- S. grairimicus individuals appear (Ortega, 1986) just plement de iézards: les sdnddes de la savane de when prey ahundance is starting to be the highest ~~~t~ (cate uIvoire). Unpubl. These de Doctor- (Ortega and Hernandez, 1983), perhaps allowing sciences, univ,paris VI, growth at the fastest rates. The growth rates observed . 1974. Structure et dynamique d'un peuple- for younger S. gramrnicus individuals at La ~ichilía ment de lézards: les scincideSde la savane de L~~- (0.390 mmiday) are higher than those reported for to (Cote D'lvoire). La Tcrre et la Vie 28:352-428. other Sceloporus species, such as S. 7iirgafus (0.193 mm/ . 1975. Dynamique des populations de lezards. day; Smith, 1996), S. irndulafus (0.300 to 0.348 mml ~~11.soc. zool, F~~~~~ 99:345-361, day; Parker, 1994), and S. jarrovi (0.200 to 0.380 mm/ -. 1981. Ccologie des population et des peuple- day; Smith and Ballinger, 1994). ments. Masson Ed. Paris. Comparing the S. grammicus population of la Mi&- BEIITALANFFY,L. 1957. Quantitative laws in metaho- ilía with the populations studied by Lemos-Espina1 lism and growth. Q. Rev. ~iol.32:217-231. and Ballinger (1995a) at Laguna (0.074 to 0.099 mm/ -. 1960. Principies and theory of growth. Iri W. day) and paredon (0.075 to 0.098 mmlday), we also W, Nowinsky (ed.), Fundamental Aspects of Nor- found faster growth rates in the younger individuals mal and Malignant Crowth, pp. 137-259. Elsevier at La Michilía. La Michilía is located in the Northwest publishing Co. Amsterdam. moiintains of Mexico. The populations skdied by Le- CHABREK,R. H., AND T. JOANEN.1979. Growth rates mos-Espina1 and Ballinger (1995a), Laguna and Pa- of American alligators in Louisiana. Herpetologica redon, are located in Central Mexico volcanic moun- 3.55-57. tains (around 19"lO'N and 9So36'W).Both study sites DUNHAM,A. E. 1978. Food availability as proximate are located at high elevations, Laguna at 3700 m and factor infiuencing individual growth rates in the Paredon at 4400 m (Lemas-Espina1 and Ballinger, iguanid lizard Sceloporus merriami. Ecology 59:770- 1995a). 13espite marked seasonality in the rainfall al 778. al1 three sites which is concentrated in the summer, Fox, S. F. 1983. Fitncss home range quality and ag- tht. average temperature conditions are at least 8 C gression in Utu Sturisbirriana. In R. B. Huey, R. Pian- colder at Laguna and Paredon as compared with La ka, and T. W. Schoener (eds.), Lizard Ecology: Michilía. Ctudies of a Model Organism, pp. 149-168. Har- The timing of birth may result in the early matu- vard Unit: Press, Cambridge, Massachusetts. ration (five months) of S. gramniicus at La Michilía, GUIT.I.EI.TE,L. J., AND G. CASAS-ANDREU.1980. Fall re- (Ortega, 1986). Other montane Sc~lriporusspecies ma- productive activity in the high altitude Mexican ture at five months, such as S. jarrmi (Ballinger, 1973; lizard, Sceloporus grammicus microlyidotus. J. Her- Ruby, 1977, 1978). Sixty percent of the S. jarraii fe- petol. 14:143-147. males studied by Ballinger (1973) matured at five --, AND --- . 1981. Ceasonal variation in fat