ROBIN ANDREWS (Natural Resource Ecology Laboratory, Colorado State 
University, Fort Collins, Colorado 80521), in collaboration with A. S. 
Rand and working with anole populations on Barro Colorado Island and in 
the anole facility at Balboa, has summarized the major characteristics 
on the reproductive biology of anoline lizards as follows: 
1. Reproductive effort in Anolis is a function of rate of reproduction 
(one egg every one to two weeks in small Central American anoles) and 
hatchling size (proportional to species size). 
2. Differences in reproductive effort, whether seasonal or spatial, 
involve alterations in rate. Thus A. limifrons hatchlings are larger in 
the dry season, apparently as a result of longer retention of the eggs 
before laying. 
3. The small clutch size and frequent ovipositions characteristic of 
anoles seem true also for other small lizards of relatively equable tropical 
habitats. This reproductive strategy contrasts strongly with that found in 
lizards of temperate and strongly seasonal habitats (large numbers of eggs 
laid in one or few clutches). 
4, One important contributing factor to these contrasting reproductive 
strategies is postulated to be differences in predation pressure. 
High predation pressure on anoles and other small lizards in the tropics 
results in relatively r—selected reproductive strategies: small clutches 
can be laid at frequent intervals at low cost to the female; at the same time 
the early maturity of the female increases the probability that she will 
reproduce before death. 
On the other hand, predation pressure on temperate lizards is relatively 
low. Hence their reproductive strategy is determined by the environmental 
restraints of the limited periods suitable for the incubation and development 
of the young. For them, therefore, large and few clutches are optimal 
because they can be timed for the critical periods, 
Robin Andrews has also collected data on the contrasting character- 
istics of island (Dominica) and mainland (Panama, Costa Rica) anoles: island 
anoles appear to be food-limited while mainland anoles are probably controlled 
by predation, Thus island anoles have relatively low growth rates which can, 
however, be increased markedly with increase in food. Mainland species, on 
the other hand, have high growth rates that are not (in one species) increased 
by greater supplies of food. They differ also in their trophic position. 
Island anoles are the dominant insectivores (few higher order predators) in 
their depauperate insular faunas, while mainland anoles are relatively 
unimportant insectivores (many higher order predators) in the complex habitats 
of the mainland tropics. Some other contrasting features follow from these. 
