226 
Discussion 
somehow irrelevant to the behavior of these 
animals in the wild. I believe that such an 
attitude may be misguided. Over the last 10 
years, a body of literature has emerged from 
the learning laboratory which indicates quite 
clearly that lizards are capable of a wide 
variety of learned behaviors. It is difficult 
for me to understand just how the ability 
could have evolved in the first place were it 
not exhibited by animals in the wild. 
In this connection, it is important to under- 
stand that the paradigms studied by com- 
parative psychologists are not simply labora- 
tory curiosities but are, at least in many 
cases, representative of situations encoun- 
tered routinely by animals in their normal 
habitats. For example, the paradigm known 
as passive avoidance learning refers to a 
situation in which an animal learns to with- 
hold a response — under certain stimulus 
conditions — which otherwise has a high 
probability of occurring. This is precisely the 
kind of behavior which underlies the putative 
success of the Batesian mimic. Another ex- 
ample would be the capacity for “latent learn- 
ing” as discussed by Dr. Brattstrom. Re- 
cently, Philabosian has suggested that this 
type of behavior may occur in Anolis cris- 
tatellus. The point is that one cannot safely 
ignore the implications of these laboratory 
studies on lizards — that is, that learning may 
play a significant and unsuspected role in 
the naturally occurring behavior of this very 
successful vertebrate group. 
I would also like to suggest that it may 
be productive to think of learning ability 
(or, more properly, abilities — since there 
are many different types of learning) as an 
evolutionary strategy which may affect the 
survival of a species just as, for example, the 
tendency to develop digital lamallae or 
species-specific displays. Like any character, 
certain lineages should exhibit more highly 
developed learning capabilities than others 
— and it may be possible to relate this dif- 
ferential distribution of learning ability to 
either taxonomic status or type of niche 
utilization. For example, large predatory 
lizards, especially opportunistic hunters such 
as Varanus komodoensis described by Dr. 
Auffenberg might be expected to rely more 
heavily on learned behaviors than lizards 
which occupy a highly structured, relatively 
invariant, behavioral niche. Whatever the 
distribution of learning ability across lizard 
species, it is reasonable to expect that such 
a capability will play a role in the naturally 
occurring behavior of lizards and in the adap- 
tive success of certain Saurian taxa. 
HEATH to REGAL: Why couldn’t a 
reptile just develop an unusually large heart 
for its size? Reptiles are generally small- 
hearted. This is a path that they could fol- 
low. Increased perfusion of the tissues can 
be accomplished by increasing capillary 
diameters as well. 
REGAL: Increasing size will not increase 
efficiency, and efficiency is what might count 
in competition between two or more other- 
wise comparable species. I would have to 
have data on what the benefits would be of 
enlarging an “inefficient” heart relative to 
the costs. We lack the data to answer your 
question. 
GANS: At an equivalent temperature, 
reptiles have a lower metabolic rate than 
birds or mammals. So one could raise a 
larger herd of dinosaurs on a pasture of 
land than a herd of cows. Ectotherms can 
maintain more mass on an equivalent energy 
input. 
REGAL: Yes, I agree that there are dis- 
tinct advantages to ectothermy just as there 
are to endothermy and I believe that we 
should spell these out. 
GANS: Crocodilians have essentially four- 
chambered hearts, and yet their metabolic 
rates are still low. This illustrates that there 
are advantages to ectothermy. Reptiles can 
maintain a larger biomass than mammals 
on an equivalent amount of food as long as it 
is possible for them to get away with paying 
the price, which may be resigning themselves 
to basking or sit-and-wait predation, or 
whatever. 
REGAL: Yes. I see no reason why 
endothermy should automatically be selected 
for because of a four-chambered heart. The 
heart simply allows selection for intense 
activity strategies to proceed and the species 
may be superior in competition of the 
appropriate sort. 
