Anolis acutus

About: Anolis acutus is a research topic. Over the lifetime, 7 publications have been published within this topic receiving 196 citations. The topic is also known as: sharp anole.

The Population Ecology of the Lizard Anolis Acutus

Abstract: Populations of Anolis acutus, the only anole on St. Croix, U.S. Virgin Islands, were studied for three years. A mark and resight method, used to estimate population size, was tested twice by capturing the entire population studied; the error in estimating the adult population was 3% and 13%. Structural and climatic habitats, diurnal activity, distance to nearest neighbor, migration, survival, and homing were also studied. The species has one of the densest lizard populations known, at one locality an average of 0.43 lizards/m2-density ranged 2,000-5,600 lizards/ha, biomass 13-23 kg/ha. A single tree may have a population of 80 adult lizards and a biomass of 300 g. Anolis acutus has a broader structural habitat than other solitary anoles, occupying a range of perches from near ground level to the tops of the highest trees. The lizards are active from before sunrise to after sunset with no peaks of activity or basking behavior. Territories are small; the mean distance to nearest neighbor was 1.5 m for males, 0.7 m for females, and 0.5 m for male-female pairs. The mean survival over 12 mo was 12% for adult males and 37% for adult females. Adult males homed rapidly; 50% returned when displaced 71-90 m. Migration rate of adults is low. Attempts to re- locate adults were unsuccessful since the lizards deserted the new site. Adults are sedentary and once having established a territory on a tree rarely move from that tree. Immigration into a tree devoid of resident lizards is primarily by juveniles. The habitat partitioning results from the adults excluding juveniles from trees. Egg and/or juvenile mortality may function to regulate the population size.

Reproductive Cycle and Growth in the Lizard Anolis acutus

Abstract: Anolis acutus is an endemic species and only anole on the island of St. Croix, U. S. Virgin Islands. A high percentage of ovigerous females are present during most of the year, with January thru April being the months of lowest reproductive potential. However, even during these months ovigerous females may exceed 50% of the adult females. Reproduction can take place during all twelve months of the year. Maximum testes size occurs from June thru October. In females fat bodies were rarely large, and were smallest during the dry season (December-April). Fat body size showed no temporal pattern in the males. Maximum reproductive potential is correlated with months of high rainfall, and the lowest reproductive potential with months of low rainfall. Females lay a single egg at a time. Eggs range from 10.7-11.4 mm long and 7.4-8.6 mm wide and are buried in sandy or gravelly soils. Fourteen days after laying eggs weigh 0.32 g. Hatching occurs in about 30 days at 28 C. Hatchlings are 19-21 mm snout-vent and weight 0.21-0.30 g. The average growth rate of juveniles is 0.07 mm/day, of females it is 0.06 mm/day, and of males, 0.11-0.14 mm/day. Females apparently reach sexual maturity in less than a year and males in about one year. Minimum size of sexually mature females is 36 mm snout-vent, and their maximum size is 49 mm. Males appear to reach sexual maturity at about 50 mm snout-vent and reach a maximum size of 67 mm.

Food Intake and Reproduction in Anolis acutus

Abstract: The relationship between food intake and reproduction was investigated in an eastern and a western population of the iguanid lizard Anolis acutus on the island of St. Croix. Reproduction was higher in the west than in the east. Females with oviductal eggs were present in every sample in the west, but were absent until May in the east. Small fat bodies accompanied the higher reproduction in the west. Initially, fat bodies were large in the east, but as reproduction increased, fat levels decreased. Food intake, as measured by stomach weights, was not significantly different between localities. To investigate whether an increase in food intake increases reproduction, lizards in the east were fed supplementally over 51 days. Reproductive effort (100 x gonad weight/lean body weight) failed to increase in females but did increase in males. The reproductive condition of females was identical between food augmented and control lizards, but fat levels increased tremendously in food augmented lizards. The weight of fat bodies was 6 x greater than controls in females, and 8 x greater in males. An increase in food did not cause an increase in female reproduction in this anole.

Aggression in the Lizard Anolis acutus

Abstract: The aggressive behavior of adult males and females of the iguanid lizard Anolis acutus was studied in the field. Aggressive encounters were classified as low intensity or high intensity. A. acutus has a high population density, small territories and a single tree has numerous males and females. The unit of observation for each study was a single tree. The observations on a tree included the number of lizards seen every 5 min interval, the number and intensity of encounters, and on trees with marked lizards the position and activity of each lizard. An aggression index was calculated for each population on a tree: the number of encounters per hour divided by the number of lizards sighted per hour X 10. Undisturbed populations demonstrated a "normal" level of aggression; aggressive encounters increased linearly as the number of lizards observed increased. Encounters doubled with a doubling of the population. The aggression index did not increase with an increase in the population. Males and females demonstrated equivalent levels of aggression and in a given population the aggression of one sex was independent of the other. Removing a lizard from a tree caused an immediate increase in aggression that subsided when the vacated territory was reoccupied. The return of a previously removed lizard also increased aggression. Most aggressive encounters observed were of low intensity, and high intensity encounters were more common in disturbed than in undisturbed populations. The methods used permit a quantitative study of the relationship between territory and aggression.