Appendix A
Geographic location
The study area is located in Sierra Nevada, SE Spain (36ºN, 03ºW; Fig. S1).
This mountain system presents the highest altitudinal range in the Iberian Peninsula
(200-3481 m asl), and a rather stepped slope.
In this mountain system, mean temperature decreases 0.46ºC every 100 m of
elevation (Fig. S1). Above 2000 m asl, precipitation falls usually in form of snow
during the cold season, and the snow cover lasts for around 6 months of the year
(November-May). Below 2000 m asl, precipitation in spring and autumn, and snow
melting, in summer, keep the atmosphere relatively humid during a part of the year;
nevertheless, summer is hot and dry, typical of a Mediterranean climate.
Vegetation in Sierra Nevada is strongly influenced by this climatic gradient
(Valle, 2003). In lowlands, Eucalyptus sp. (exotic), Populus alba, small patches of
Quercus ilex and crops of Oliva europaea and Prunus dulcis represent the tree layer;
Rosmarinus officinalis, Retama sphaerocarpa and thorny Genista sp. are the most
abundant shrubs. As altitude increases, trees are replaced first by Castanea sativa, then
by Quercus pyrenaicus and Q. ilex again; Genista sp. shrubs are abundant also at
middle altitudes. At higher altitudes, there are plantations of Pinus sylvestris up to 2400
m asl; over the timberline, meadows with Juniperus oxycedrus, Juniperus sabina and
Genista florida appear. Above 3000 m asl, only grassy vegetation appears in summer,
when the absence of snow permits.
Fig. S1 – Altitude and mean values of precipitation and temperature in Sierra Nevada.
S1
Sampling Stations
We conducted our work on the southern slope of Sierra Nevada, where we chose
six sampling stations (2 ha each approximately) separated from one another by about
500 meters elevation, at 300, 700, 1200, 1700, 2200 and 2500 m asl (Fig. S1), all
stations having a south orientation. Only 17.33 km linear distance separates the lowest
from the highest sampling station.
S300: this is located at 300 m asl (36º53’N, 3º24’W), beside the River
Guadalfeo. The climate is characterized by hot summers and generally frost-free
winters. The vegetation is composed of an allochthonous Eucalyptus sp. forest, a
Populus alba forest, and several shrubby areas dominated by Rosmarinus officinalis and
Retama sphaerocarpa, with Genista sp., Artemisia sp. and Thymus sp.
S700: this is located at 700 m asl (36º55’N, 3º26’W), beside a deep ravine
carved by a stream. The climate is similar to that in S300. Trees are not abundant,
although there are some extensive orchards of Olea europaea and solitary Prunus dulcis
and Ficus carica. Shrubby vegetation consists mainly of Cystus sp., Retama
sphaerocarpa, Rosmarinus officinalis and Genista sp.; Foeniculum vulgaris, Capparis
spinosa and Ruta graveolens are also present.
S1200: this is located at 1200 m asl (36º56’N, 3º25’W). Some irrigation canals
cross the ground. The climate consists of hot summers with infrequent frosts in winter.
Dispersed Castanea sativa individuals represent the dominant tree vegetation, with
some Morus nigra and Ficus carica. Shrub formations consist mainly of Genista sp.,
although Cystus sp. also appears.
S1700: this is located at 1700 m asl (36º57’N, 3º26’W), on steeply sloped terrain
where the climate is characterized by warm summers and frequent frosts with snowfall
in winter. The dominant trees species are Quercus rotundifolia and Q. pyrenaica, while
Genista sp. and Cystus sp. are abundant shrubs.
S2200: this is located at 2200 m asl (36º58’N, 3º19’W) around a melt-fed spring.
The climate is characterized by warm summers and very frequent freezes with abundant
snowfall in winter, covering the ground with a snow layer of variable thickness. Dense
plantations of Pinus sylvestris are found at this altitude; both in forest clearings and in
meadows, the dominant shrub is Genista florida.
S2500: this is located at 2500 m asl (37º01’N, 3º19’W) around some melt-fed
springs and not far from the Mulhacén river. The climate is similar to that in S2200, but
harsher in winter. No trees appear, being above the timberline. Creeper Juniperus
communis and Genista florida sub-alpine meadows are the main shrubby formations
here.
Habitat structure
We chose sites with physical and biotic characteristics varying as little as
possible, particularly with respect to vegetation cover and height. Nevertheless, flora
varied all along the gradient. To measure the vegetation structure in each sampling
station, we randomly set a 50-meter-long transect, marked every meter, five times over
the land, and recorded the absence or presence of vegetation, and the height and the
kind of plant found at every one-meter mark of the string; plant height was classified as
< 25 cm, 25 - 50 cm, and > 50 cm, because those plant-height values determine major
habitat differences for the shrub-linked lizard Psammodromus algirus. Two important
components of the landscape, vegetation cover (Fig. S2) and vegetation height (Fig. S3)
S2
did not statistically differ with elevation (vegetation cover: χ25 = 0.09, P = 1.00;
frequency of plants of 25-50 cm: χ25 = 0.16, P = 1.00). These results suggest that all of
our sampling stations where occupied by the shrubby vegetation physiognomy where P.
algirus lives (Salvador, 2011).
Aknowledgements
The authors want to thank Manuel Pizarro for the maps (Fig. S1) for this Appendix.
Cited bibliography
Salvador, A., 2011. Lagartija colilarga – Psammodromus algirus (Linnaeus, 1758).
Enciclopedia Virtual de los Vertebrados Españoles. Salvador, A., Marco, A. (Eds.).
Museo Nacional de Ciencias Naturales, Madrid. http://www.vertebradosibericos.org/.
Valle, F., 2003 (Ed.). Mapa de series de vegetación de Andalucía. Ed. Rueda, Madrid.
Fig. S2 – Percentage of ground surface covered by vegetation in each altitude (n = 253 spots measured at
each altitude).
S3
Fig. S3 – Percentage of ground surface covered for each vegetation-height category in altitude (n = 253
spots measured at each altitude).
S4