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120 IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 NATURAL HISTORY RESEARCH REPORTS

Foraging Mode and Locomotion
Foraging mode has molded the evolution
of many aspects of lizard biology. From a
basic sit-and-wait feeding strategy, several
lizard groups have evolved a wide forag-
ing strategy, slowly moving through the
environment using their highly devel-
oped chemosensory systems to locate
prey. MCELROY ET AL. (2008. Journal of
Experimental Biology 211:1029–1040)
studied locomotor performance, whole-
body mechanics, and gaits in a phyloge-
netic array of lizards that use sit-and-wait
and wide-foraging strategies to contrast
the functional differences associated with

the need for speed versus slow continu-
ous movement during foraging. Sit-and-
wait species used only fast speeds and
trotting gaits coupled with running
(bouncing) mechanics. Different wide-
foraging species independently evolved
slower locomotion with walking (vault-
ing) mechanics coupled with several dif-
ferent walking gaits, some of which have
evolved several times. Most wide foragers
retain the running mechanics with trot-
ting gaits observed in sit-and-wait lizards,
but some wide foragers have evolved very
slow running mechanics. In addition,
three evolutionary reversals back to sit-
and-wait foraging are coupled with the
loss of walking mechanics. These findings
provide strong evidence that foraging
mode drives the evolution of biomechan-
ics and gaits in lizards and that several
means of evolving slower locomotion
exist. In addition, the different gaits used
to walk slowly appear to match the eco-
logical and behavioral challenges of the
species that use them.

Is Melanism Adaptive 
in Sea Kraits?

Ontogenic melanism (progressive darken-
ing of the skin) has been documented in
snakes. Black coloration of the skin often
compromises the cryptic effects associated
with other patterns (e.g., zigzags) and
exposes individuals to predation; however,
the mortality risk presumably can be bal-
anced, for example, by a thermoregula-
tory advantage during basking. Such
adaptive context has been proposed to
explain the appearance and the mainte-

nance of melanism in snake populations.
Based on a very large capture/recapture
sample (>8000 observations) gathered on
two species of Sea Kraits (Laticauda saint-
gironsi and L. laticaudata in New
Caledonia), LORIOUX ET AL. (2008.
Amphibia-Reptilia 29:1–5) observed that
melanism occurred in only one species (L.
laticaudata), was infrequent, and affected
only adult snakes. None of three adaptive
hypotheses respectively linked to ther-
moregulation, predation, or protection
against sun radiation, provided a satisfac-
tory account for the occurrence of
melanism in the study populations.
Therefore, the authors suggest that
melanism was a fortuitous phenomenon.

Signal for 
Mating Success and Survival

Many species of lizards have colored
spots on the flanks that may function as
ornaments. SALVADOR AND VEIGA (2008.
Amphibia-Reptilia 29:117–120) investi-
gated the between-years stability of the
blue patch color saturation and the rela-
tionships between color saturation, mat-
ing success, and survival in males of the
lizard Psammodromus algirus. Saturation
values of the anterior blue patch of males
were significantly repeatable across years.
Survivors had more saturated patches
than non-survivors among paired males
but not among non-paired males. The
positive relationship between blue patch
saturation and survival suggests that this
morphological trait acts as a reliable sig-
nal of male quality measured by adult
survival.

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

Anoles, such as this Anolis stratulus (top)
from the British Virgin Islands, are classic sit-
and-wait predators that use elevated perches
to scan the area below for prey. In contrast,
Dominican Ground Lizards, Ameiva fuscata
(bottom), employ a wide-foraging strategy,
slowly moving through the environment
using their highly developed chemosensory
systems to locate food. 

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Melanism in Black-banded Sea Kraits (Laticauda laticaudata) is not linked with thermoregula-
tory efficiency, protective coloration, or protection against solar radiation. 

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IGUANA  •  VOLUME 15, NUMBER 2  •  JUNE 2008 121NATURAL HISTORY RESEARCH REPORTS

Courtship Behavior in 
Four-eyed Spotted Turtles

LIU ET AL. (2008. Amphibia-Reptilia
29:185–195) recorded 168 courtship
sequences from 12 male and 18 female
adult captive Four-eyed Spotted Turtles
(Sacalia quadriocellata) and described 30
male and four female discrete motor pat-
terns. Male display patterns involved tac-
tile and visual signals to induce female
receptivity to mating. In response,
females may emit olfactory signals for
gender recognition. Female rejection of
male suitors resulted in a male success
rate of 4.17%. Only seven copulations
were observed. Copulation occurred only
when a female became quiescent and
relaxed her tail for coition.

Reproduction and Sexual 
Dimorphism in a Night Lizard

RAMÍREZ-BAUTISTA ET AL. (2008.
Amphibia-Reptilia 29:207–216) studied
reproductive characteristics of the night
lizard, Lepidophyma sylvaticum
(Xantusiidae) from cloud forest in
Tlanchinol, Hidalgo, Mexico. Males
reached sexual maturity at a snout-vent
length (SVL) of 55 mm, and females

reached sexual maturity at a SVL of 56
mm. Males and females were not sexually
dimorphic in SVL, but males had signif-
icantly larger heads and limbs than
females. Reproduction in males and
females was seasonal. Testicular mass
increased in July and August, reaching
maximum size in September. Minimum
testes size occurred in March. Follicles of
females began to increase in size in
September when vitellogenesis was
observed. Follicles in some females
increased in mass during January–March,
whereas other females ovulated during
that period. Late embryonic stages
(35–40) were observed in July with par-
turition likely occurring in July and
August, coincident with maximum rain-
fall. Litter size averaged 4.7 ± 0.4
neonates, and was not correlated with
female size. Similarities in reproductive
characteristics between L. sylvaticum and
other xantusiids (viviparity, long gestation
period) suggest that some reproductive
characteristics have a historical origin.

Predation by Brown Anoles 
on Spiders in Taiwan

NORVAL ET AL. (2007. Russian Journal of
Herpetology 14:191–198) analyzed stom-
ach contents in 502 Brown Anoles
(Anolis [Norops] sagrei) from an area sur-
rounding a plant nursery in Santzepu,
Taiwan. The stomachs of 166 lizards
contained spiders, which were removed
for identification to establish a basis upon
which future studies on spider predation
by N. sagrei in Taiwan can be based.
These spiders comprised 298 individuals

from 13 families. Unlike other studies,
which found that these lizards prey
mainly on web spiders, the majority of
the spiders in this study are ground-
dwelling species. The results from this
study suggest that this exotic invasive
species is predominantly terrestrial at this
locality.

Microhabitat Characteristics for
Reptiles in Latvia

CEIRANS (2007. Russian Journal of
Herpetology 14:172–176) examined veg-
etation characteristics of reptilian micro-
habitats using 280 circular plots through-
out Latvia. The lizard Lacerta agilis
preferred xeric sites, and, at the other end
of the gradient, both snake species
(Natrix natrix and Vipera berus) preferred
mesic sites with a tall herbaceous layer
and shrubs. The legless lizard Anguis frag-
ilis often was associated with relatively
intact pine forest, whereas the other rep-
tiles were associated mainly with dis-
turbed sites and grass cover.

Reproduction in the tropical night lizard
Lepidophyma sylvaticum is seasonal, with
young born during periods of maximum
rainfall. 

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Brown Anoles (Anolis sagrei) in Taiwan often
are highly terrestrial and feed heavily on
ground-dwelling spiders. 

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The Slow Worm (Anguis fragilis) was more
frequently associated with intact pine forest
than other Latvian reptiles. 

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Courtship of male Four-eyed Spotted Turtles
(Sacalia quadriocellata) involves tactile and
visual signals. In response, females may emit
olfactory signals.

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Color saturation of the anterior blue patch of
male Psammodromus algirus was an “honest”
signal of a male’s quality. 

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