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IGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 179NATURAL HISTORY REPORTS

Morphology and Diet of Two
Sympatric Snakes

PINTO ET AL. (2008. Amphibia-Reptilia
29:149–160) described the morphome-
try and diet of two sympatric species of
Chironius (C. flavolineatus and C. quadri-
carinatus) from Brazilian Cerrado. The
two species differ in external morphol-
ogy, with C. flavolineatus longer and C.
quadricarinatus heavier. Each species also
showed marked sexual size dimorphism.
Both species feed exclusively on frogs
with a heavy preference for hylids, and
may have a tendency to eat small prey.
These two species have brownish ground
colors and exhibit no ontogenetic varia-
tion, suggesting that juveniles and adults
use similar substrates. Chironius flavolin-
eatus and C. quadricarinatus are semi-
arboreal, forage actively, and usually feed
on the ground. Chironius flavolineatus
uses higher vegetation for resting and,
based on morphological results, seems to
be more arboreal than C. quadricarinatus.

A unique life history among
tetrapods: An annual chameleon

living mostly as an egg
The ~28,300 species of tetrapods (four-
limbed vertebrates) almost exclusively
have perennial life spans. KARSTEN ET AL.
(2008. Proceedings of the National
Academy of Sciences of the United States of

America 105:8980–8984) discovered a
remarkable annual tetrapod from the arid
southwest of Madagascar: The chameleon
Furcifer labordi, with a posthatching life
span of just 4–5 months. At the start of
the active season (November), an age
cohort of hatchlings emerges; larger juve-
niles or adults are not present. These
hatchlings grow rapidly, reach sexual
maturity in less than 2 months, and
reproduce in January–February. After
reproduction, senescence appears, and
the active season concludes with popula-
tion-wide adult death. Consequently,
during the dry season, the entire popula-

tion is represented by developing eggs
that incubate for 8–9 months before syn-
chronously hatching at the onset of the
following rainy season. Remarkably, this
chameleon spends more of its short
annual life cycle inside the egg than out-
side of it. A review of tetrapod longevity
(>1,700 species) found no others with
such a short life span. These findings sug-
gest that the notorious rapid death of
chameleons in captivity may, for some
species, actually represent the natural
adult life span. Consequently, a new
appraisal may be warranted concerning
the viability of chameleon breeding pro-
grams, which could have special signifi-
cance for species of conservation concern.

World’s Smallest Snake
Islands are viewed as natural evolutionary
laboratories for terrestrial organisms
because they have boundaries that limit
dispersal and often reveal evolutionary
patterns and mechanisms. One such pat-
tern is that the smallest and largest
species of different types of tetrapod ani-
mals are frequently found on islands.
HEDGES (2008. Zootaxa 1841: 1–30)
described two new diminutive species of

N A T U R A L  H I S T O R Y  R E P O R T S

Both Chironius flavolineatus (top) and C.
quadricarinatus (bottom) are semi-arboreal,
forage actively, and usually feed on the
ground, but the former is more slender and
elongate, suggesting that it is more arboreal. 

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Furcifer labordi from Madagascar spends
most of its life inside an egg. 

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The Barbados Threadsnake (Leptotyphlops carlae) may be the world’s smallest species of snake.

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snakes of the genus Leptotyphlops from
the Lesser Antilles: One from Saint Lucia
(L. breuili) and the other from Barbados
(L. carlae). The species from Barbados is
the world’s smallest snake, with a total
adult length of approximately 100 mm.
Limited evidence indicates a clutch size
of one and a greatly elongated egg shape.
Comparison of egg shapes in snakes indi-
cates that the shape is a packaging phe-
nomenon, related primarily to the shape
of the available body cavity and clutch
size. The body shape of snakes also varies
and influences the shape of snake eggs.
The smallest snakes are typically stout-
bodied, whereas the longest snakes usu-
ally are more slender. The allometry of
organ size also affects clutch size and
shape, because the smallest snakes have
the smallest proportion of body cavity
space available for reproduction. The best
explanation for the observation of body
size extremes on islands is that colonizing
species have adapted to open ecological
niches that would otherwise be occupied
on the mainland. Island colonists
encounter novel environments and
reduced interspecific competition, allow-
ing species to evolve physical traits,
including extremes in size, not normally
seen on continents. However, the lower
limit of adult size appears to be con-
strained by the allometry of morphology,
physiology, and reproduction. The small-
est tetrapods have small clutches, usually
one egg or young, and offspring that are
relatively large. In the smallest snakes,
offspring are one-half of the length of
adults, compared with 10% adult length
in the case of large species of snakes.
Thus the evolutionary tradeoff between
number and size of offspring appears to
have reached a size boundary in these

species, limiting the evolution of yet
smaller species.

Niche Relationships and 
Interspecific Interactions in 

Antiguan Lizard Communities
Anolis lizards are the focus of most
Caribbean lizard community ecology
studies, with few studies including other
common species that might influence
community structure. To study niche
relationships and interspecific interac-
tions in Antiguan lizard communities,
KOLBE ET AL. (2008. Copeia 2008:
261–272) used five offshore islands with
varying combinations of three diurnal
lizards: Ameiva griswoldi, Anolis leachii,
and Anolis wattsi. The authors collected
data on perch height, substrate, thermal
microhabitat, body size, head length,
daily activity, and abundance to charac-
terize the ecological niche of each species.
Ameiva griswoldi was more similar to A.
leachii in size and daily activity, but more
similar to A. wattsi in perch height, and
A. leachii and A. wattsi were more similar
in thermal microhabitat. This pattern of
niche differentiation was consistent with
niche complementarity, where species are

similar on some niche axes but differ on
others. Using the same niche characteris-
tics as in species comparisons, we tested
for a niche shift among islands for 
A. wattsi. In the absence of A. griswoldi,
A. wattsi used lower perches, sunnier
microhabitats, and was found more often
on the ground. In contrast, with A.
leachii absent, A. wattsi perched higher,
more often in the shade, and on trunks.
Furthermore, A. wattsi was most abun-
dant when with A. leachii only, but least
abundant when alone with A. griswoldi.
These results suggest interspecific inter-
actions, most likely due to competition
and intraguild predation, are important
for structuring Antiguan lizard commu-
nities.

180 IGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 NATURAL HISTORY REPORTS

The Antiguan Ground Lizard, Ameiva gris-
woldi, affected habitat use and abundance of
Anolis wattsi on small islands near Antigua.

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The Barbuda Bank Tree Anole (Anolis
leachii) also affected habitat use by smaller
Anolis wattsi on Antiguan satellite islands.

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