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Intl. J. of Mol. Evol. and Biodivers. 2011, Vol. 1, No. 1-5
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3
Wald χ
2
=0.049, df=1, P=0.849; air temperature: Wald
χ
2
=0.437, df=1, P=0.509; wind speed: Wald χ
2
=0.582,
df=1, P=0.445).
Figure 4 The mean percent of vegetation cover per site
Note: Kruskal-Wallis Test shows cover was not significantly
different per site (χ
2
=2.412, df=3, P=0.491)
2 Discussions
2.1 Escape distance
Since lizard abundance and vegetation cover did not
differ significantly between sites, this indicates that
lizard abundance is not related to vegetation cover.
This is surprising because Stamps (1983) showed that
vegetation structure played a critical role in reptile
habitat selection for predator escape. Additionally, this
vegetation cover has also been used for foraging
(Karasov and Anderson, 1984), and mating (Diaz and
Carrascal, 1991).
Algyroides marchi
is a lizard
endemic to the mountainous region of south-east
Iberian Peninsula. The more stoney and vegetated the
environment, then the less abundant they are (Rubio
and Carrascal, 1994). This could relate to
A.
erythrurus
and
Psammodromus
sp,
which could
explain why lizard abundance was not correlated with
vegetation cover (Figure 3; Figure 4).
The habitats did not differ in percent vegetation cover
(Figure 1). This is supported by previous research;
both
P. algirus
(Diaz and Carrascal, 1991) and
A.
erythrurus
population densities are correlated with
leaf litter and low dense shrub cover (Martín and
López, 2003), which was available in similar amounts
on all of our sites. Hence, this is also why the
Mann-Whitney Test showed that lizard species did not
differ in their relative escape distances.
2.2 Lizard abundance
One would expect morning counts of lizards to be
greater than in the afternoon. In the morning,
A.
erythrurus
were more active in the river valley, while
in the afternoon, were more active in gypsum desert
(Figure 2). Busack (1976) showed that while
A.
erythrurus
activity peaks in the morning, adults stay in
cool microhabitats but within their thermal limits,
which allow them to remain active throughout the day.
A. erythrurus
was the only species found on April 3, a
cloudy day when the air temperature was lower and
the relative humidity was higher, which support
Busack (1976)’s results. In contrast,
P. hispanicus
cannot raise their body temperatures on cloudy days
via basking, and hence are unable to forage for long
periods of time (Patterson and Davies, 1984), which
may explain why they were not seen on April 3.
Additionally,
A. erythrurus
could be found in the river
valley in the morning. However, it should be noted
that there was a high chance of duplicate sightings of
the same individual as we were unable to mark the
species we documented.
Given the desert’s natural sloping landscape, this
could have been a reason why more lizards were
found there (Figure 2). Likewise, the aspect was also
significant, as nearly all of the lizards (n=44) were
sighted where the sun was hitting the ground, and only
(n=3) were not. Bohorquez-Alonso et al (2011)
discovered
Gallotia galloti
, another Lacertid, were
mostly found oriented parallel or perpendicular to the
sun. Also, Arribas (2010) studied activity and
microhabitat selection between two Pyrenean rock
lizards, both Lacertids found in Spain. He discovered
that
Iberolaceria aurelioi
were found on steeper areas
than
I. bonnali
and
I. aranica.
Further studies should
be conducted analyzing slope together with aspect to
determine if the sun is hitting the slopes in the gypsum
desert more directly in the afternoon than the evening,
which would explain our result.
The Fisher’s Exact Test showed that the different
species of lizards had no preference for a particular
habitat. One possible explanation could be because
they have evolved adaptations for both environments.
For example, another lizard found in our study area,
the ocellated lizard (
Lacerta lepida)
is found in warm,