Rates of oxygen uptake increase independently of changes in heart rate in late stages of development and at hatching in the green iguana, Iguana iguana.

Oxygen consumption (VO2), heart rate (fH), heart mass (Mh) and body mass (Mb) were measured during embryonic incubation and in hatchlings of green iguana (Iguana iguana). Mean fH and VO2 were unvarying in early stage embryos. VO2 increased exponentially during the later stages of embryonic development, doubling by the end of incubation, while fH was constant, resulting in a 2.7-fold increase in oxygen pulse. Compared to late stage embryos, the mean inactive level of VO2 in hatchlings was 1.7 fold higher, while fH was reduced by half resulting in a further 3.6 fold increase in oxygen pulse. There was an overall negative correlation between mean fH and VO2 when data from hatchlings was included. Thus, predicting metabolic rate as VO2 from measurements of fH is not possible in embryonic reptiles. Convective transport of oxygen to supply metabolism during embryonic incubation was more reliably indicated as an index of cardiac output (COi) derived from the product of fH and Mh. However, a thorough analysis of factors determining rates of oxygen supply during development and eclosion in reptiles will require cannulation of blood vessels that proved impossible in the present study, to determine oxygen carrying capacity by the blood and arteriovenous oxygen content difference (A-V diff), plus patterns of blood flow.

Rediscovery of the 220-year-old holotype of the Banded Iguana, Brachylophus fasciatus (Brongniart, 1800) in the Paris Natural History Museum.

The Paris Natural History Museum herpetological collection (MNHN-RA) has seven historical specimens of Brachylophus spp. collected late in the 18th and early in the 19th centuries. Brachylophus fasciatus was described in 1800 by Brongniart but its type was subsequently considered as lost and never present in MNHN-RA collections. We found that 220 year old holotype among existing collections, registered without any data, and we show that it was donated to MNHN-RA from Brongniart's private collection after his death in 1847. It was registered in the catalogue of 1851 but without any data or reference to its type status. According to the coloration (uncommon midbody saddle-like dorsal banding pattern) and morphometric data given in its original description and in the subsequent examination of the type in 1802 by Daudin and in 1805 by Brongniart we found that lost holotype in the collections. Another MNHN-RA specimen has Horn Islands (Wallis and Futuna) as the collection location but we show that most of the collections given to MNHN-RA by its collector, Louis Arnoux, have mixed localities in the MNHN-RA catalogues. We thus conclude that the locality is wrong and that the species never inhabited those islands located west of Western Samoa and north-east of Fiji.

Effect of lysine addition on growth of black iguana (Ctenosaura pectinata).

The effects of the addition of lysine to commercial feed given to captive black iguana (Ctenosaura pectinata) were evaluated in terms of growth and feed digestibility. Twenty-eight-day-old black iguana with an initial weight of 5.5 ± 0.3 g were housed individually in cages measuring 45 × 45 × 45 cm. The experiment lasted 150 days. The ambient temperature ranged from 28 to 35°C with a relative humidity of 60 to 95%. Treatments consisted of the addition of different percentages of lysine to the feed (0.0, 0.1, 0.2, and 0.3%, dry matter [DM] base). There was a linear response (P < 0.01) in daily gain (68, 112, 118, and 151 mg/d) and daily intake (251, 289, 297, and 337 mg/d) for levels from 0 to 0.3%, respectively, as well in the growth in head size, snout-vent length, and total length. The digestibility of DM, neutral detergent fiber, and acid detergent fiber were reduced linearly (P < 0.01) as lysine levels increased. Intake and digestibility were negatively correlated (r = -0.74; P < 0.001). It is concluded that the addition of lysine to the black iguana diet in the first months of life is important to stimulate growth and intake.

Compensating for a bad start: catch-up growth in juvenile lizards (Amphibolurus muricatus, Agamidae).

In most natural environments, food availability varies unpredictably through space and time, and growth rates of individual organisms respond accordingly. However, growth rates are not necessarily a simple function of current nutritional conditions: growth rates can be affected by earlier nutritional experience as well as current circumstances. Thus, even a brief period of dietary restriction early in life might influence growth rates later on: either reducing them (if early experience sets subsequent rates, as in the "silver spoon" effect) or increasing them (if underfed individuals can compensate by growing more rapidly to cancel out the early decrement). Alternatively, later growth may be unaffected by earlier rates of growth. We experimentally manipulated food supply (and thus, growth rates) of hatchling lizards (Amphibolurus muricatus) for 1 month post-hatching, then maintained both high-food and low-food animals under identical nutritional conditions in outdoor enclosures for another 6 months. Low food abundance early in life significantly reduced juvenile growth, but these previously underfed animals exploited the subsequent (common garden) conditions to grow much faster than their larger (initially better-fed) siblings. Thus, the two groups were indistinguishable in body size at 6 months of age. Intriguingly, the compensatory growth occurred in winter, a period that is generally unsuitable for rapid growth in ectotherms.

Intraspecific allometry of standard metabolic rate in green iguanas, Iguana iguana.

To study the allometric relationship between standard metabolic rate and body mass (mass range 16-3627 g) in green iguanas, Iguana iguana (n=32), we measured rates of oxygen consumption (V(O(2))) at 30 degrees C during scotophase. The relationship could be described as: V(O(2))(ml h(-1))=0.478W(0.734). The resulting mass exponent was similar to the 3/4 power commonly used in interspecific curves (P>0.05), but differed from a proposed intraspecific value of 2/3 (P<0.05). The mass exponents of male (n=8) and female (n=11) iguanas did not differ (P>0.05). The mass adjusted V(O(2)) was higher than predicted from generalized squamate curves. The mean mass exponent of intra-individual allometric equations of iguanas (n=7) at varying masses during ontogeny did not differ from that of the pooled equation, indicating that scaling of V(O(2)) is similar for both between and within individuals. Thermal acclimation, compensatory changes in V(O(2)) with prolonged exposure to a constant temperature, was not observed in juvenile iguanas (n=11) between 1 and 5 weeks of acclimation at 30 degrees C.

Postnatal skeletal ontogeny in Callisaurus draconoides and Uta stansburiana (Iguania: Phrynosomatidae).

The mineralization of the skeleton from hatching to near maximum size in two phrynosomatid lizards, Callisaurus draconoides and Uta stansburiana, is described in detail. Observed patterns in the appearance of epiphyseal secondary centers, ossification centers, apophyseal ossifications, and calcifications, the distribution of sesamoids, and the timing of fusions, are compared and contrasted with observations of other squamates available in the literature. Overall, Callisaurus and Uta exhibit an advanced state of ossification in the hatchling relative to other squamate neonates and share a similar sequence of braincase fusions and appearance of secondary centers. Preliminary observations suggest that patterns of postnatal skeletal development are highly conserved and independent of patterns of prenatal morphogenesis, and thus a potentially rich source of character data for systematic investigations.

Dietary fiber influences nutrient utilization, growth and dry matter intake of green iguanas (Iguana iguana).

Herbivory is an uncommon feeding strategy in lizards. Appropriate diet formulations for captive lizards should be based on performance measures, yet few data are available on the effect of plant fiber on food intake, nutrient utilization and growth of captive herbivorous lizards. This study was conducted to determine the effect of three levels of dietary fiber on dry matter intake, nutrient and energy metabolizability and growth rate of the green iguana (Iguana iguana). Twenty-one captive iguanas were fed nutritionally complete diets containing three levels of dietary fiber: 19, 24, and 27% neutral detergent fiber. The iguanas were fed each diet for at least 12 wk, and total excreta were collected for 11.3 +/- 4.0 d (means +/- , range of 7 to 25 d). Diets and excreta were analyzed for dry matter, organic matter, gross energy, neutral detergent fiber, acid detergent fiber, and acid detergent lignin. The study was designed as a Latin square crossover. Across all diets, dry matter intake was proportional to body mass1.0 (BM). Growth rate was greater (P < 0. 05) when iguanas were fed the low and medium fiber diets (2.2 and 2. 4 g/d, respectively) than when fed the high fiber diet (1.4 g/d). However, mean daily dry matter intake of the three diets [7.2 g/(d. kg BM)] was not different. In general, digestibility of fiber fractions and the metabolizability of dietary energy decreased (P < 0.05) as the level of dietary fiber increased. These data suggest that a diet containing less than 27% neutral detergent fiber should be fed if rapid growth is to be sustained during intensive captive production of green iguanas.

Growth of juvenile green iguanas (Iguana iguana) fed four diets.

Wild green iguanas consume a primarily folivorous diet. As pets in captivity, they suffer high mortality and malnutrition. Nutrient requirements are not established. The purpose of this study was to compare growth in juvenile iguanas fed three commercial diets and a romaine-based diet. Twelve nominally 4-wk-old iguanas were fed in a latin square design each of four diets for 8 wk, consisting of a 2-wk accommodation period and a 6-wk collection period. Diets were analyzed at the beginning and end of the study. Food consumption was measured daily; body weights and lengths were measured weekly. For Diets A, B, C and D mean body weight gains were--3, 6, 31 and 60% in 6 wk, respectively. Gain in body weight and snout-vent length increased linearly with dietary protein and fiber and with dry matter intake. The data suggest that growth in pet green iguanas may achieve rates for farmed and wild green iguanas when diets are palatable and contain adequate protein and fiber.

Effects of chemical and visual exposure to adults on growth, hormones, and behavior of juvenile green iguanas.

For 1 year, groups of juvenile male green iguanas (Iguana iguana) were housed such that one group was visually exposed to an adult female, a second group was both visually and chemically exposed to an adult female, a third group was visually exposed to an adult male, and a fourth group was both visually and chemically exposed to an adult male. Juvenile males exposed to signals from adult males showed signs of chronic stress, including reduced growth rates, lower testosterone levels, higher corticosterone levels, and decreased frequencies of headbob display. Although visual exposure alone was sufficient to suppress growth, testosterone levels, and rates of display, the addition of chemical exposure strengthened some of these effects. Both chemical and visual exposure to an adult male were necessary to produce elevated corticosterone levels. In contrast, juvenile males exposed to visual and chemical signals from an adult female exhibited growth rates, hormone levels, and behavior patterns typical of juvenile males housed in the absence of adults of either sex. These results suggest that visual and chemical signals from dominants may serve to reinforce social relationships among males through their influence on the physiology and behavior of receivers.