Ecology of an Amazonian lizard assemblage
An assemblage of lizards was studied in a remote part of the Colombian Amazon. Thirty-one
species were collected and identified, making the study site the second highest area for
species richness within Amazonia, and the third most diverse In the world. The study site
could be classified as 'virgin' forest, practically untouched by man. Structurally Intact, and
with flora and fauna present at few remaining sites within Amazonia the Caparü field site
promised to be an interesting location to study the ecology of a little studied group.
The autecology of each species present at the study site was investigated: species
abundance, spatial distribution, diet, activity patterns and reproduction patterns. The results
presented here show that the lizard assemblage Is both highly organized and complex
Finally, the biogeography of both the Capani lizard assemblage, and that of the Amazon as a
whole was also considered.
Uzards were found in very low abundances, similar to other studied Amazonian
localities (some species only collected once over the two year sampling period). The most
abundant species where found to be those with both a generalist lifestyle and a wide
distribution. The rarest species were often the most specialized, although extremely limited
data was available and such conclusions are preliminary. Most species were dietary
generalists, and where specialization occurred it focused on ants. All but one species present
at the study site were diurnal. Uzard activity appears to follow the general diurnal lizard
pattern, which is highly correlated with both temperature and rainfall. The assemblage was
comprised of both heliotherms and non-heliotherms and basking species were most abundant
in forest gap areas. The limited reproductive data available shows that the lizards present are
aseasonal breeders, breeding throughout the year. All but one species was oviparous, and
the other being ovoviviparous.
Different methods were used to identify the individual niches of each lizard species.
Niche breadths were highest in the most common species and overlap generally quite low. A
positive correlation was also identified between niche breadth and body size. Micro habitat
was found to be the most important structuring factor in the community, followed by diet.
Interspecific competition is predicted to be very low.
The Capard lizard assemblage was found to be most similar to other Upper
Amazonian sites, although several similarities were shared with Guianan saurofaunas. In
general, similarity decreased with increased distance between site pairs. Multivarlate
analysis of locality data identified several regions of high species community similarity, and a
major division between lizard faunas from eastern and western Amazonia was evident. Local
endemism and areas of high diversity were compared with data from other groups such as
birds and butterflies found in the literature. Such distribution patterns (including those
identified here) suggest a reduction In forest cover and subsequent spedation in the
Quaternary period. Biogeographical analysis based on combined distribution maps was
performed and fourteen general distribution patterns were selected, adding to those already
identified in the literature.