Ants as Prey of Juvenile Anolis lineatopus (Rept., Iguanidae) in Prey Choice Experiments

2. Tierpsychol., 65, 66-76 (1984) @ 1984 Verlag Paul Parey, Berlin und Hamburg ISSN 0044-3573 / Intercode: ZETIAG

Arbeitsgruppe fur Verhaltensforschung, Abteilung fur Biologie, Ruhr-Universitat Bochum

Ants as Prey of Juvenile Anolis lineatopus (Rept., Iguanidae) in Prey Choice Experiments

BY PETER VOGEL and FRIEDERIKE VON BROCKHUSEN-HOLZER

With 4 figures

Received: December 15, 1982

Accepted: May 18,1983

Abstract and Summary

In prey choice experiments, hatchlings of Anolis lineatopus attadted ants less readily and spat them out more frequently than ather arthropods. With rising ant body size (from 2 to 4 mm), the rate of hatchlings attacking the ants decreased rapidly (from 55 to 21 %), while the rate of spitting them out rose (from 0 to 52%). Stinging ant species were attacked by hatchlings as often as similar sized stingless ones but were spat out more often. Older but still ant-naive juveniles attacked ants progressively. The stinging Solenopsis geminata and the stingless Pheidole fallax are two ant species living syntopically with A. lineatopus. When the stinging species was offered exclusively, juveniles only very occalsionally attacked it whereas they took considerable numbers of P. fallax when offered alone. A mixed offering of both species induced no consistent rejection of the stinging ant nor consistent acceptance of the stingless one. Experience with 5. geminata restrained further attack on both ant species whereas experience with P. fallax encouraged it.

The results suggest that the attack on ants bears certain risks for a foraging anole that vary with ant weaponry. Hatchlings cannot distinguish between harmful and harmless species. This could explain their general reluctance to take mts. Up to a certain degree, older juveniles still mix up stinging and stingless ants and feed on them according to their prior experience.

Introduction

Prey-naive hatchlings of Anolis lineatopus reject certain prey items taken by others (VON BROCKHUSEN and CURIO 1975, VON BROCKHUSEN 1977); while 60 % of the hatchlings attacked all five species tested, 40 % rejected one, two

Ants as Prey of Juvenile Anolis lineatopus in Prey Choice Experiments 67

or three of them. With increasing age the anoles attacked the offered prey more readily: when older than two weeks, 87 % of the juveniles took all five species.

HELLER (1980 a, b) developed several selection models to explain the coexistence of “ethotypes”, i. e. “prey acceptors” and several “prey rejectors” (rejecting prey items). H e assumed that both rejection of a suitable prey and acceptance of a less suitable prey involve a loss of fitness. One of his models is based on the presence of a harmful and a similar but harmless prey so that the predator cannot distinguish between them.

This assumption could possibly apply to ants. Within the Formicidae, a variety of antipredatory mechanisms have been developed. Castes, species, and species groups differ considerably with respect to the presence and composition of poisons, the apparatus for the application of the poison, form and size of the mandibles (CAVILL and ROBERTSON 1965; MASCHWITZ and KLOFT 1971; WILSON 1971; LECLERCQ 1977; KUGLER 1978, 1979; SCHMIDT 1978) as well as the ability to launch a mass (counter-)atta& (RISING 1981).

With the exception of the mandibles, these mechanisms can hardly be perceived by a visually hunting predator such as an anole (CURIO and MOBIUS 1978). Thus, for example, a stinging ant can look quite similar to a stingless one.

Stomach contents of various anole species often include considerable numbers of ants (SCHOENER 1968; ANDREWS 1971; FLEMING and HOOKER 1975; LISTER 1976; LESCURE and FRETEY 1977; STAMPS et al. 1981); this applies also to A. lineatopus (RAND 1967 a; LISTER 1976; HETTRICH 1981). Anoles are obviously by no means general ant rejectors. However, some findings suggest that ants may represent a particular kind of anole prey: (1) Stomachs of juvenile A. fineatopus contain fewer ants than those of adults (RAND 1967 a); (2) Anoles seem to prefer certain ant species (HETTRICH 1981; STAMPS et al. 1981), and ( 3 ) During seasons with low food availability, anoles eat more ants than in seasons when food is abundant (FLEMING and HOOKER 1975; HETT- RICH 1981; STA~MPS et al. 1981).

Investigations were carried out to determine (1) if hatchlings were able to distinguish between ants and other arthropods, (2) if hatchlings were able to distinguish between ant species, and (3) how experience with ants influences the response of older juveniles to these insects. The results will be discussed in relation to HELLER’S (1980 a, b) “Harmful Prey” selection model.

Materials and Methods

Anolis lineatopuj is an endemic Jamaican lizard (UNDERWOOD and WILLIAMS 1959) inhabiting the trunk-ground range in forested as well as open areas (RAND 1967b). Juvenilcs hatch with a snout-vent length (SVL) of about 19nim and have a mean growth rate in the field between about 1 and 2 mm per 10 days, depending on the season; females reach a SVL of ca. 50 mm, males of ca. 72 mm (RAND 1967a; VOGEL, in press).

For the experiments, anoles of three age classes were used: juveniles 1 were maximally 2 weeks old, juveniles 2 were more than 2 weeks but less than 2 months, and juveniles 3 were older than 2 months. The experiments were run in Bochum (FRG) using anoles raised there

5‘’

68 PETER VOCEL and FRIEDERIKE VON BROCKHUSEN-HOLZER

(VON BROCKHUSEN 1976), and in MonaiKingston (Jamaica). In Kingston, juveniles 1 were obtained from eggs either collected in the field or laid by freshly captured females; older juveniles were captured in the field.

VON BROCKHUSEN (1977) described maintenance in Bochum. In Kingston, cages similar to those in Bochum were set up in a well-ventilated room. Anoles visually isolated from each other received prey through a hole in the box lid.

Response of Juveniles 1 to Ants and other Arthropods

Subjects were offered 26 prey types representing 24 species (number of types in brackets): Formicidae (S), Lepidoptera (1: larva), Coleoptera (4: 3 larvae, 1 imago), Diptera (3),

Homoptera ( I ) , Heteroptera (2), Isoptera (2: worker, nasute), Orthoptera (2), Arachnida (2), and Isopoda ( 1 ) . In Kingston we tested 18 (including 6 ant species) of these 26 prey types, in Bochum 8 (including 2 ant species). Each prey type was offered to a t least 20 juveniles 1.

To compare responses to ants of different sizes, the 8 ant species tested were grouped in 3 sizes, i.e. small (body length about 2 mm; Monomorium floricola, Tapinoma melanocephalum), medium (body length 2.5 mm to 3.5 mm; Pheidole fa l lax , Solenopsis geminata, Crematogaster breuispinosa, Pseudomyrmex flauidulus), and large (body length about 4 mm; Lasius niger, L. flavus). Neither the small nor large ants tested can sting. Among the medium sized species, t w o are able to sting (S. geminata, Pseudomyrmex flavidulus), and two are not (Pheidole fallax, C . brevispinosa).

A prey item was considered “attacked” if the anole grasped it wi th its mouth within 3 min. If there was no attack, another item usually taken by all anoles (e.g. mealworm) was offered. If the anole attacked this second item within another 3 min the first item was considered “rejected”, otherwise it was registered as “not eaten” and excluded from da ta analysis.

For each prey type tested the rate of attack was calculated as

R A = number of anoles attacking prey

number of anoles attacking or rejecting prey ’ and the rate of spitting out prey as

number of anoles spitting out prey number of anoles attacking prey

RS = ’

Development of Response to Ants in Ant-naive Juveniles

At Bochum, juveniles which had never encountered ants before were offered either the black Lasius niger (45 juveniles 1, 45 juveniles 2, 22 juveniles 3) or the yellow L. flavus (64, 63 and 22 respectively). Data were analysed by a 3-way conltingency-test (SOKAL and ROHLF 1981).

Response of Juveniles 2 to Repeatedly Offered Stinging and Stingless Ant Species

Both the stinging Solenopsis geminata and the stingless Pheidole fallax are myrmicine ants occurring syntopically with A. lineatopus. To the unaided human eye their dark brown to black workers look alike. In 3 tests a t Kingsiton juveniles 2 were offered workers of these two species, both with a body length of about 3 mm.

1) T w o groups of freshly caught anoles contained 4 subjects each. After a starvation period of 3 days, one group was fed stinging ants exclusively, the other stingless ones. For 10 days, each anole was offered ants one by one up to a maximum of 10 per day. However, if an anole failed to attack an ant within 3 min, no more ants were offered that day. After these 10 days, the group which got the stingless species first was fed the stinging one in the same way for another 10 days.

2) Before the experiment, 6 subjects were kept in separate cages for 2 weeks and fed various prey items (including S. geminata and P . fallax), and were then starved for 3 days.


For 12 days each subject was then offered 6 prey items in random order per day, i.e. stinging and stingless ants (P. fa l lax, Crematogaster brevispinosa, S . geminata), a termite worker, a coleopteran larva and a coleopteran imago. Each prey item was exposed for maximally 3 min.

3) For 2 weeks 12 subjects were caged, receiving various prey items (including stinging and stingless ants), and then starved for 3 days. The following experiment was divided into 3 periods (a, b, c) of 10 days each. Each day, 3 prey items were offered, i.e. a first ant (ant l ) , a second an t (ant 2), and finally a termite worker. Ant 1 was stingless during period a, stinging during period b, and again stingless during period c. Ant 2 was invariably stingless. For each prey item offered the time between introduction and attack (latency) was measured. If the prey was not attacked within 3 min, latency was registered as “more than 3 min”. Each period was subdivided into 3 intervals (3-4-3 days) and for each anole median latencies per interval and per ant were calculated. The first 2 intervals of period a allowed the anoles to be- come habituated, and were excluded from the statistical analysis.

Prey Attack Inhibition through Ant Stinging

A t Bochum an experiment was carried out using the stinging ant Myrmica laeuinodis. Two groups of juveniles 2 containing 23 anoles each were starved for 3 days. In the following experiment, the abdomen of a prey item seized with tweezers was genitly pressed onto the bottom of the anole’s buccal cavity. For one group this prey was a coleopteran larva (Afphi - tobius diaperinus), for the other M . laeuinodis. Each prey item was used once only. Imme- diately after this treatment the anole was returned to its box together with a prey item ( A . diaperinus for both groups). Every 10 min a check was made to see whether the anole had taken the prey.

Test procedures followed SOKAL and ROHLF (1981), and SACHS (1974). Unless otherwise indicated, levels of statistical significance are two-tailed.

Results

Response of Juveniles 1 to Ants and other Arthropods

Comparison between ants and other arthropods: On average, juveniles 1 attacked the tested ants less readily (median RA = 43 %) and spat them out more frequently (median RS = 24 %) than the rest of the arthropods tested (median RA = 84 %, median RS = 0 %; Mann-Whitney U-tests, p < 0.01 for both RA and RS). Ranges of rate of attack and rate of spitting out both overlapped for the two prey groups (range of RA for ants: 18-58 %, for other arthropods: 15-100 %; range of RS for ants: 0-56 76, for other arthropods: 0-89 %). Non-ant prey most often rejected were nymphs of the Jamaican firebug, Dysdercus jamaicensis (RA = 15 %). We observed that 6 out of 8 ant species were spat out (see below) but only 3 out of 18 non-ant prey types (Tribolium castaneum adults: RS = 89 %; Armadillidium pictum: RS = 21 %; nasuti of Nasutiformes spec.: RS = 10 %). Behaviour towards Tribolium adults contrasted remarkably with that towards ants: the beetles were readily attacked (RA = 90 %) but spat out with few exceptions.

Comparison between ants: The larger the ant the less it was attacked (2 X 3 contingency-test, x* = 18.60, p < O.001) and the more it was spat out (2 X 3 contingency-test, = 17.30, p < 0.001). With ant body length increasing from 2 to 4 mm, attack rate fell from 55 to 21 %, whereas spitting out rate rose from 0 to 52 % (Fig. 1). This clearly contrasts with the findings on other arthropods: juveniles 1 attacked larvae of holometabolan insects up

70 PETER VOCEL and FRIEDERIKE VON BROCKHUSEN-HOLZER

60

50

10

0

Fig. I : Hatchling rate of prey attack and rate of spitting out prey with respect to ant size. - Rate of prey attack;

___._ rate of spitting out prey \ /

/ /

/

/ /

4’

2 3 4 mm

ANT BODY S I Z E

to 10 mm body length almost invariably and never spat them out. Within the medium sized ant species attack rate did not differ (p > 0.4), yet subjects spat out the stinging species more frequently than the stingless ones (RS =

53 %, n = 19 vs. RS = 10 %, n = 23; 2 X 2 contingency-test, xz = 9.842, p < 0.005).

Development of Response to Ants in Ant-naive Juveniles

The effect of anole age on prey attack did not differ significantly for the two ant species tested (G-test, 3-way interaction n. s.). Older anoles attacked ants more readily than younger ones did (G-test, p < 0.0001); Lasius niger was taken less often than L. flawus (G-test, p < 0.0002; Fig. 2). Juveni- les of all age classes spat out about half the attacked ants. There was no significant influence of either anole age or Lasius species 03 rate of spitting out.

Response of Juveniles 2 to Repeatedly Offered Stinging and Stingless Ant Species

1) Group 1 receiving only the stingless Pheidole fallax attacked more and more of the offered ants and took the possible maximum of 40 ant specimens on the last two days. In the subsequent test only Solenopsis geminata were offered; the subjects still attacked a considerable number during the first two days but completely stopped attacking during the next two days. Group 2 receiving the stinging species exclusively attacked only 3 of the offered ants (Fig. 3).

2) Receiving both ant species in an unpredictable manner, subjects still attacked P. fallax more frequently (? = 75 %) than S. geminata (2 40 %; Dixon and Mood sign-test, p < 0.05). However, the anoles eating comparatively few S. geminata also tended to take only few P. fallax (r, = 0.857, p < 0.05, one-tailed). A significant correlation was obtained between the frequency of attack on the stinging ant and the combined frequency of attack

Ants as Prey of Juvenile Anolis lineatoprrs in Prey Choice Experiments 71

00

.-a Lasius flavus 7 0

Fig . 2: Rate o f prey attack of ant-naive juveniles with respect to anole age. 0-0 Lasius niger;

60

5 0 v

w 4 0 + U

30

2 0

1-2 2 -7 8-18 w e e k s

ANOLE AGE

on the two stingless P. fallax and Crematogaster brevispinosa (r, = 0.943, p < 0.02). Apparently anoles rejecting the stinging species also hesitated to attack the stingless ones. Experience with S. geminata led to a reluctance to attack a subsequently offered P. fallax: on days when the stingless species was offered before the stinging one, median attack latency for the stingless one was 15 s, whereas it rose to 135 s on days with the reversed sequence (Dixon and Mood sign-test, p < 0.05). During the first 4 days, the combination “stingless ant attacked, stinging one rejected” was as frequent as during the last 4 days (Cochran Q-test, I* = 4.813, p > 0.5).

3) Both attack latencies for ant 1 and ant 2 differed significantly between intervals (Friedman-tests: x2 = 35.321, D F = 6, p < 0.001; x2 = 30.152, DF = 6, p < 0.001). The attack latency for ant 1 rose continuously after the stingless species was replaced by the stinging one (period b). At the end of

G R O U P 1

\ \ Fig . 3: Number of ants attadted

Y ‘- 7 per group and day. During the first \ 10 days, juveniles were offered 0

4 10 I- \ P. fullax (group 1) or S. geminata

\ (group 2) exclusively. In a sub- I-

sequent test, group 1 received S. geminata instead of P. fallax.

P. fullax offered; - - - - -

‘--

61 3 5 7 9 11 1 3 DAY

T I ME S. geminata offered

72 PETER VOGEL and FRIEDERIKE VON BROCKHUSEN-HOLZER

12 4 - 8 ;

period b more than half the stinging ants were rejected. After this species was replaced by the stingless one the attack latency decreased, but at the beginning of period c still tended to be higher than in period a (Fig. 4). Attack latency for ant 2 changed analogously to ant 1, though ant 2 was stingless throughout the experiment. Particularly during the last intervals of period b, ant 2 was attacked significantly later than during period a and the end of period c (Fig. 4).

/

/ F i g . 4 : Attack latency in mixed / offerings of stinging and stingless

ant species. Intervals indicate time smedule of experiment. Below ab- )( \

'180 1 R

Attack Latency after being Stung

Anoles treated with larvae of darkling beetles (Alphitobius diaperinus) waited for 25 min (median value) before attacking the next prey. By contrast, anoles treated with Myrmica laevinodis, and thereby most probably stung, needed 75 min (median value) to attack again. This difference is highly significant (Mann-Whitney U-test, p < 0.001).

Discussion

The response of Anolis lineatopus hatchlings (juveniles 1) to ants as well as other prey varied individually. O n average, however, ants were rejected and spat out by more hatchlings than the other arthropods tested. This ten- dency became more pronounced the larger the ants were (Fig. 1) . These changes in behaviour towards different ant size classes cannot be explained by size alone since hatchlings coped with much larger non-ant prey. Hatch- ling rate of attack on similar sized stinging and stingless ant species did not differ, though the stinging ones were spat out more frequently. This suggests that hatchlings are sensitive to ant poison but cannot distinguish on sight between stinging and stingless species.


Older but still ant-naive juveniles attacked ants progressively (Fig. 2). We cannot decide whether this resulted from the juveniles’ experience with non-ant prey or whether i t reflected a predetermined developmental process. The latter case would suggest that older (larger) anoles are less susceptible to ants.

Experience with stinging and stingless ant species influenced the response of juveniles. The stinging Solenopsis geminata was only rarely attacked when solely offered although the juveniles must have been very hungry, receiving no alternative prey. By contrast, the stingless Pheidole fallax was taken more and more when offered exclusively (Fig. 3). A mixed offering of both species elicited no consistent acceptance of stingless nor consistent rejection of stinging ants. Experience with the stinging species apparently restrained the juveniles’ readiness to attack both subsequently offered ants. O n the other hand, experience with the stingless species obstructed a permanent rejection of the stinging one but enhanced the attack on both species. Juvenile anoles obviously generalized their experience, applying that made with stinging to stingless ants and vice versa. Yet these generalizations from one species to the other did not lead to a complete confusion of the two ants; in mixed offerings the stingless ant was still attacked more readily than the stinging one (Fig. 4).

The selection model “Harmful Prey” (HELLER 1980 a, b) assumes that the predator confuses harmful prey with a harmless one similar in appearance and invariably either rejects or accepts both. This assumption is met only in part. U p to a certain degree, the juveniles indeed mistake one ant for the other but they change their behaviour according to prior experience. If only one species is met, they quickly learn to accept or reject it. The model “Harmful Prey”, therefore, has to be reformulated to include learning of prey details.

HELLER’S model further assumes the existence of a prey which reduces the fitness of a predator attadcing it. What risks might be involved in ant attack? Our experiments with S. geminata and M . laevinodis suggest that stinging restricts the readiness for further prey attack. Apart from stinging, the ants’ mandibles could be an effective weapon against predators: In some cases it was observed that an attacked ant firmly grasped the anole’s mouth with its mandibles and stuck there for hours; if the ant was attached to the exterior of the mouth, the anole would usually try to shake or strip it off. This might again prevent attack on the next prey for a certain time. Additionally, at- tempts to get rid of an ant could expose the anole to a visually hunting predator of its own. Larger ants have larger mandibles; in the case of soldiers they are even disproportionately enlarged. This could explain the steep fall of attack rate with rising ant body size (Fig. 1). On a Jamaican study site, density of A. lineatopus was found to be less in a patch heavily infested by the aggressive ant Crematogaster brevispinosa than in a patch without this ant; caged together with 38 C. brevispinosa specimens, a juvenile died from their mass attack within hours (VOGEL 1983). RISING (1981) found that the iguanid lizard Phrynosoma platyrhinos, a specialist feeding mainly on ants and termites, avoids ant species counter- attacking in mass. This mobbing response could force the predator to move on,

74 PETER VOGEL and FRIEDERIKE VON BROCKHUSEN-HOLZER

thus increasing his own risk of being detected by a visually hunting predator. The case of C. brevispinosa further suggests that under certain circumstances the mobbing itself endangers the lizard.

Salamanders (Plethodon cinereus) take longer to digest ants than other arthropods of equal size, perhaps because of their comparatively high chitin con- tent (JAEGER and BARNARD 1981). If ants are less profitable than other prey they should be avoided - according to optimal foraging theory (PYKE et al. 1977; KREBS 1978) - as long as more profitable prey is abundant. Indeed, some findings suggest that anoles take fewer ants when other arthropods are plentiful ( F L ~ M I N G and HOOKER 1975; HETTRICH 1981; STAMPS et al. 1981). However, the difference between the anole’s treatment of various ant species as reported here cannot be explained by a difference between the metabolic rewards of ant and non-ant prey. In accordance with HELLER’S model “Harm- ful Prey”, the attack on certain ant species seems to be risky: it might restrain further food intake, cost time and effort to get rid of an attached ant, re- lease a mass counter-attack, and increase the anole’s exposure to predators.

Hatchling A. lineatopus also rejected other arthropod species at various rates, though on average less often than ants. A number of experiments suggest that some of these rejections are caused by mistaking the rejected prey (e. g. nymphs of Gryllus bimaculatus and of Acheta domesticus) for an ant (VON BROCKHUSEN in prep.). In other cases such an explanation seems inap- propriate. Nymphs of the firebug Dysdercus jamaicensis were attacked by only 15 ”/o of the hatchlings although they hardly resemble ants. Possibly there are various prey groups containing both harmful and harmless though similar species. In addition, a harmless prey may possess traits of several harmful types. Still another explanation is needed for the case of Tribolium castaneum. Though the hatchlings frequently spat out this beetle, they also readily attacked it. Prey-naive predators would be expected to show such behaviour if the prey is unpalatable but imposes only little risk in comparison to the gain from feeding on similar palatable species.

Rejection of certain palatable prey types is also known from adult anoles (CURIO 1970). It is not yet known if and how this phenomenon is connected with juvenile prey avoidance.

Zusammenfassung

In Beutewahlversuchen griffen Schlupflinge von Anolis lineatopus Amei- sen seltener an und spuckten sie haufiger aus als andere Arthropoden. Mit ZU- nehmender Ameisengrofle (von 2 auf 4 mm) nahm derAnteil der angreifenden Schlupflinge rasch ab (von 5 5 auf 21 %), derjenige der ausspuckenden aber zu (von 0 auf 5 2 %). Stechende Ameisen wurden von Schlupflingen zwar mit gleicher Haufigkeit angegriffen wie stachellose, aber haufiger ausgespuckt. Altere, doch noch Ameisen-naive Jungtiere griffen Ameisen zunehmend an.

Die stechende Solenopsis geminata und die stachellose Pheidole fallax sind zwei mit A. lineatopus syntop vorkommende Ameisenarten. Erhielten die


Jungtiere nur die stechende Art, griffen sie diese nur selten an, frai3en aber betrachtliche Mengen der stachellosen, wenn diese allein geboten wurde. Eine gemischte Darbietung der beiden Ameisenarten fuhrte weder zu einer bestandigen Ablehnung von S. geminata noch zu einer bestandigen Annahme von Pheidole fallax. Erfahrungen mit S . geminata hemmten weitere Angriffe auf beide Arten, wahrend Erfahrungen mit P. fallax die Angriffe forderten.

Nach diesen Befunden ist der Angriff auf Ameisen, entsprechend deren Abwehreinrichtungen, fur die rauberischen Anolis mit einem Risiko verbunden. Die Schlupflinge vermogen nicht zwischen gefahrlichen und ungefahrlichen Ameisen zu unterscheiden. Dies konnte ihre generelle Abneigung, Ameisen an- zugreifen, erklaren. Altere Jungtiere verwechseln in gewissem Mai3e immer noch stechende und stachellose Ameisen und greifen sie je nach fruherer Er- fahrung an.

Acknowledgements

This study was supported by the Deutsche Forschungsgemeinschaft (Cu 4/21, 4/25). We would like to thank Ingrid CEBULLA and Willi HETTRICH for their indispensable help during the experiments. In Jamaica, P. VOGEL enjoyed the hospitality of Prof. Dr. I. GOODBODY and his staff of the Department of Zoology a t the University of the West Indies. Dr. W. HUTHER and R. R. SNELLING kindly helped with the identification of the an t species. We are very much indebted to Prof. Dr . E. CURIO and the other members of the Arbeitsgruppe fur Verhal- tensforschung a t the Ruhr-Universitat Bochum, as well as to an anonymous referee, for critical and encouraging comments.

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Authors’ address: Dr. P. VOGEL and F. VON BROCKHUSEN-HOLZER, Arbeitsgruppe fur Verhaltensforsdmng, Abteilung fur Biologie, Ruhr-Universitat Bochum, Postfach 102148, D-4630 Bochum.

Documents

Ants as Prey of Juvenile Anolis lineatopus (Rept., Iguanidae) in Prey Choice Experiments