1. Biodiversity distribution in the
western Sahara-Sahel: the role of
environmental variation
Ricardo Nuno Ferreira Martins Guerreiro
201101595
Biologia, 2013/2014
Supervisor:
José Carlos Brito, Senior Scientist, Assoc. Researcher,
FCUP/CIBIO

2. 1
ABSTRACT
Fieldwork Biology implies certain techniques and methods that streamline work in a more
effective and safe way. The main aim of the present internship was to learn some of these
techniques and have a first contact with fieldwork in Biology. This was done in a 48 days
field trip to North-West Africa, including the countries of Morocco, Mauritania and Mali, and
covering overland up to 13,000 kilometres. The trip covered five different ecoregions of
Desert and Savannah and focused on the sampling of amphibians and reptiles. The
herpetofauna found in each ecoregion was characterized and quantified in terms of diversity,
and measures of niche breadth were applied to some herpetological taxa. The distribution of
four gecko species (genus Tarentola) was evaluated against environmental factors with a
Geographical Information System. Overall, 47 taxa were found in the expedition and taxon
diversity was observed to increase in a latitudinal gradient from north to the south. Niche
breadth analyses on 11 taxa showed distinct taxa discrimination in relation to environmental
variation. The geckos of genus Tarentola sp. exhibited very different niche and spatial
occupation in closely related species, namely a preference for lower annual mean
temperatures by T. chazaliae and T. annularis and a requirement for higher annual mean
temperatures. Overall, distribution of biodiversity is latitudinally structured and tends to
follow a north-south gradient of precipitation, and there are apparent ecological niche
differences in Tarentola taxa.

3. 2
1. INTRODUCTION
North-West Africa exhibits the largest hot desert in the world, the Sahara, which separates
the Mediterranean from the Tropical climate (Figure 1), as well as it separates the Paleartic
and Afrotropical biogeographical realms (Olson et al., 2001). Overall, there is an increasing
gradient of precipitation from the northern desert areas to the southern savannah areas, until
the tropical forests (Sayre et al., 2013), although there are regional variations related with
proximity to the Atlantic Ocean and mountain ranges. Proximity to the Ocean brings more
humidity and precipitation, while high altitude disrupts the earlier patterns, tending to bring
lower temperatures and more precipitation (Hijmans et al., 2005).
Figure 1 – Biogeographical realms of the world (Olson et al., 2001).
There are several ecoregions within each Biogeographical realm, enumerated by Olson et
al. (2001), and in North-West Africa it can be identified five (Figure 2): North Saharan Steppe
and Woodlands (NS); Atlantic Coastal Desert (AC); South Saharan Steppe and Woodlands
(SS); Sahelian Acacia Savannah (SA); and West Sudanian Savannah (WS). These ecoregions
comprise xeric ecosystems with major inter and minor intra variable characteristics as soil
constitution, precipitation; temperature ranges that limit plant and animal distributions (Olson
et al., 2001).

4. 3
Figure 2- Ecoregions of North Africa (adapted from Olson et al., 2001).
North Africa has suffered a series of climatic shifts in the last 6 Million years that
successively brought dry and wet periods when the Sahara desert would arise or disappear (Le
Houérou, 1992, 1997). It is hypothesised that the desert plays an important role as a latitudinal
vicariant agent but also between mountain ranges that become isolated from each other and
retain less harsh climatic conditions, acting as refugia for biodiversity and displaying
biogeographical island-like behaviour (Gonçalves et al., 2012; Brito et al., 2014). The humid
periods may have also created longitudinal vicariance agents like rivers (Dobigny et al. 2005).
The distribution of fauna and flora of these regions follows climatic gradients, being richer
where water is present whether in form of precipitation, rivers, lakes, or rock pool, locally
known as gueltas (Brito et al., 2014). According to Le Houérou (1997), the flora of the Sahara
is dominated by Mediterranean and Tropical elements in the northern and southern areas,
respectively. According to the same author, the fauna situation is more complex, with large
mammals being essentially of Afrotropical origin, small mammals being mostly of Palaeartic
origin, and reptiles being derived almost equally from Palaearctic and Palaeotropical elements
(Lambert, 1984).
An overall greening trend has been noticed in the Sahel in the last decades, using both
remote sensing and field data (Dardel et al., 2014). However, authors like Herrmann and
Tappan (2013) point out that this greening trend may not be associated with biodiversity
gains, but rather being just associated with reinvigoration of herbaceous and shrub species,
and that tree cover is still being lost, resulting in a change of ecosystems and loss of resistance
to climatic adversity.
NS
AC
SS
SA
WS
S

5. 4
The biological knowledge on remote areas like the Sahara and Sahel is limited due to the
remote character of the region and access difficulties caused by regional conflicts (Brito et al.,
2014). This means that only a few unconnected or loosely connected exploratory missions
obtained data and there is no continuous biodiversity evaluation, resulting in coarse species
distribution maps (Le Berre, 1989, 1990). Although in the last years there was a trend for
increasing knowledge (Brito et al., 2014), it is still very important to acquire precise
information on the distribution of diversity in North Africa. For instance, recent
phylogeographic studies are finding cryptic diversity, but the distribution of such diversity is
mostly unknown (Brito et al., 2014). What is now of great importance is to sample
extensively these regions, to characterise its biodiversity, analyse taxa distributions, and relate
them with environmental factors to identify biogeographic groups.
1.1 Sampling and processing methods
There are multiple methods for sampling biodiversity, and some of the most used include:
1) Visual encounter surveys are the classic active searching of animals on foot. It includes
searching in rotten logs or tree holes, lifting stones. After seeing an active animal, the
objective is to catch him with bare hands, a noose in case of reptiles (Garcia-Muñoz et Sillero,
2010; Fritzgerald, 2012) or also a net in case of micro mammals, depending on the situation
(Hoffman et al., 1996);
2) Finding road kills is an effective way of getting DNA data that would be otherwise
difficult to access. Discrete animals like some mammals and snakes are hard to find alive and
catch but are relatively easy to find run over by cars on the road (Hoffmann et al., 1996;
Fritzgerald, 2012);
3) A very effective method to catch micro mammals is to set traps for them with bait. The
Sherman traps are small portable and foldable steel containers with a trap door. According to
Hoffman et al. (1996), the traps are deployed in regular layouts, being the most simple to
place traps at equal intervals along a line, which ideally should cover all habitat types, ideally
with one or two replicate lines. These traps are designed to catch the animals alive, but some
mortality may occur due to climatic conditions or stress (Hoffman et al, 1996);
4) Camera traps are a good asset to survey for the presence of medium-sized and large
mammals. They are also normally displaced in lines, with distances of 100 to 200 meters.

6. 5
Food baits are placed 5 meters directly in front of the cameras. Sometimes pheromone baits
are used, for example for carnivores (Hoffman et al, 1996);
5) Footprints are used for tracking down hidden individuals and to recognise elusive
species presences (Hoffman et al, 1996; Fritzgerald, 2012);
6) Scats are easily found and sometimes visually unique for a species in a region,
signalling its presence where found. They can be collected and taken to the lab for species
confirmation and DNA extraction.
1.2 Global Positioning Systems and Geographical Information Systems
The Global Positioning System (GPS) allows linking fieldwork sampling and deskwork
analysis. It enables to collect geographical coordinates of observations and samples, and to
mark tracks for geographical analyses. It also helps following pre-made routes in the sampling
design.
As defined by Haslett (1990), the “Geographical Information Systems (GIS), are computer
hardware and software packages designed to store, analyse and display spatially referenced
data”. GIS can be used to predict species distribution based on existing observation points
marked with GPS, overlapping these points with different variables like climatic, topographic,
other species presences. It is able to point out other areas with similar variables that could be
inhabitable for the studied species (Brito et al., 2009). This is an asset in conservation as it
exposes areas with higher preservation importance for the species. If done in an overarching
way, it may designate important preservation areas for general biodiversity (Brito et al.,
2014).
1.3 Richness and diversity indexes
Many indexes can be applied to analyse biodiversity patterns. Shannon index is a well-
known index for calculating habitat heterogeneity. It is based on the information theory that
tries to measure the amount of order or disorder in a system (Margalef 1958 in Krebs, 1989).
The data used is usually the number of species (species richness) and the number of
individuals in each species (relative abundance). Whereas balanced relative abundances
maximize the index.

7. 6
1.4 Objectives
The main aim of the present internship was to learn some field techniques and to have a
first contact with fieldwork in Biology. Specifically, it was aimed to: 1) gain experience in the
capture and sampling of fauna and use of GPS to collect geographic coordinates; 2)
characterize the herpetofauna of each of the five visited ecoregions: 3) quantify levels of
herpetological diversity of each ecoregion; 4) quantify niche breadth levels among the
herpetofauna; and 5) evaluate the distribution of Tarentola genus against environmental
factors.
2. MATERIALS AND METHODS
2.1 Fieldwork
A 48 days overland journey was made in two four-wheel drive vehicles, sampling
Morocco, Mauritania and Mali (Figure 3). The route of sampling covers the five Ecoregions
present in study area.
Figure 3 - Route through the five ecoregions: Atlantic Coastal Desert (AD); Northern Sahara Steppe and
Woodlands (NS); Southern Sahara Steppe and Woodlands (SS); Sahelian Acacia Savannah (SA); West Sudanian
Savannah (WS).

8. 7
Visual encounter surveys (Figure 4) were used to find animals at day and night. While
most were caught with stocking, pursuing and hand/net caching, there were different
handlings for some animals. For example: For Agama sp., (Figure 5), it was common to use a
noose in a fishing pole, also possible for Acanthodactylus sp.. For Uromastyx sp., which is
burrow builder species, a shovel would be used to dig them out of the burrow or a high-lift in
case the burrow was under a big rock (Figure 6). Amphibians were surveyed in the gueltas
and rivers with water nets (Figure 7). Venomous snakes were handled with snake-catchers
and put into cloth bags (Figure 8). Dragonflies were caught with hand nets (Figure 9). Fishes
would mostly be collected dead on dry water courses.
Figure 4 – The team performing visual encounter
surveys.
Figure 5 – Noosing an Agama agama.
Figure 6 – Use of a high-lift to help capturing Uromastyx
sp.
Figure 7-Sampling guelta for amphibians.

9. 8
Figure 8 – Using a snake catcher with an Echis
leucogaster viper.
Figure 9 – Catching dragonflies with net.
Almost every day, at sunset, 40 baited Sherman traps were deployed, distanced by 20
metres in two-replicate lines (Figure 10), trying to cover any different habitats present as
recommended by Hoffmann et al. (1996). Also seven camera-traps would be set in a line. At
sunrise they would be collected and any animal caught processed (Figure 11).
Figure 10 - Setting Sherman traps at sunset. Figure 11 – Trapped Gerbillus sp. in a Sherman trap.

10. 9
The processing of the animals was a major part the work. Normally, standard pictures were
taken in various angles to the animal (Figures 12 and 13), followed by tissue collecting: a bit
of the tail in case of reptiles (Figure 14), a toe in case of amphibians (Figure 15), a bit of ear
in case of micro-mammals (Figure 16) or a bit of a wing in case of bats, kept in alcohol for
later DNA sampling. As to road kills (Figure 17), the tissue collected would be the one which
seemed fresher.
Figure 12 - Taking pictures to an Acomys sp. Figure 13 - Standard picture of a Gerbillus sp.
Figure 14 – Cutting the point of the tail of a
Crocodylus suchus for DNA analyses.
Figure 15 – Taking an amphibian toe for DNA
analyses.
Figure 16 – Taking ear tissue of a Felovia vae for
DNA analyses.
Figure 17 – A road-killed Vulpes rueppellii.

11. 10
2.2 Levels of herpetological diversity
To quantify herpetological diversity in the study area, it was used the Shannon index (H’),
applied separately to species, genera and families to access habitat heterogeneity at different
taxonomic levels:
H’= - Σ (pi ln(pi)),
where pi is the proportion of each taxon in the total of observations in the ecoregion
considered (done for every ecoregion). That taxon could be a species (viz. Agama agama), a
genus (viz. Agama) or a family (viz. Agamidae).
2.3 Levels of niche breadth of amphibians and reptiles
To quantify the breadth of the niche of several amphibians and reptiles in the study area, it
was used the Levin’s B Index (Levins 1968, Krebs, 1989):
B= 1,
Σpj
2
where pj = proportion of the taxon’s presences in ecoregion j.
B is higher when individuals are present in more ecoregions. That result was inverted for
the Levin’s measure and then standardized (Bs) with the method described by Krebs (1989):
Bs= B-1,
n-1
where B=Levin's measure and n=total nº of ecoregions.
Bs ranges from 0.0 to 1.0 and a high Bs means no discrimination between ecoregions while
a low Bs means there is selection among ecoregions. To access the significance between the
differential proportions of taxa in the ecoregions, a χ2
-test was applied to a matrix of each
species vs. each ecoregion.

12. 11
2.4 Distribution of Tarentola genus and climatic variation
With a GIS (ArcGIS), climatic variables were examined and inputted in a map (Figure 18)
for testing their correlation with the distribution of Tarentola species. The “intersect” tool was
used to obtain the precipitation and temperature values in the observation points of the
species. “Extract multivalues” tool was used to extract those values to a bidimensional
graphic.
Figure 18 - Precipitation and temperature variation in the study area.

13. 12
3. RESULTS AND DISCUSSION
3.1 Capture and sampling of fauna
The first result is an extensive sampling in North-West Africa (Figure 19), and a vast gain
in fieldwork experience, including sampling of very different taxa as dragonflies, fishes,
amphibians, reptiles, birds and mammals. The hazards of such a journey have been personally
acquainted and acknowledged as part of the work. (Annex II).
Considering the amphibians and reptiles, a total of 559 observations were made (Annex I).
These were the start point for the further analysis, like species distribution, ecoregion
richness, and ecological niche studies.
Figure 19 – Sampling points for reptiles and amphibians along the voyage route.
3.2 Characterisation of the herpetofauna
Observed species richness of herpetofauna varied between ecoregions, being highest in the
Sahelian Acacia Savannah (SA) and West Sudanian Savannah (WS) ecoregions, and lower in
the Atlantic Coastal Desert (AD) and Southern Sahara Steppe and Woodlands (SS) ecoregions
(Figure 20). The lower species richness in ecoregion AD probably reflects the lower sampling
effort in this ecoregion, in comparison to the other ecoregions (Figure 19).

14. 13
Figure 20 – Number of species observed per ecoregion. AD: Atlantic Coastal Desert; NS: Northern Sahara
Steppe and Woodlands; SS: Southern Sahara Steppe and Woodlands; SA: Sahelian Acacia Savannah; and WS:
West Sudanian Savannah.
A total of 47 taxa of amphibians and reptiles were observed (Annex I). A great number of
individuals belonged to the families Agamidae and Phyllodactylidae, and also to Lacertidae
and Gekkonidae (Table 1). The Chamaeleonidae, Testudinidae, Boidae and Ptychadenidae
were the least represented families in the total of samples of the expedition. These numbers
reflect the relative abundance of taxa in the region, where small invertebrate-eaters like
Agama sp. and Tarentola sp. are more common than larger predators, like snakes and vipers
or varanids. Families of amphibians and water-restricted reptiles would have been observed
more if the trip was made in the wet season, which was not the case. It should not be forgotten
that the main focus of sampling was on the ground and rocks and that may be a reason for so
few tree dweller taxa like Chamaeleonidae being recorded.
0
5
10
15
20
25
AD NS SS SA WS
Nspecies

15. 14
Table 1 – Number of herpetofauna observations and samples per family.
Family N
Agamidae 158
Boidae 2
Bufonidae 13
Chamaeleonidae 1
Colubridae 20
Crocodylidae 27
Gekkonidae 61
Lacertidae 66
Phyllodactylidae 121
Ptychadenidae 3
Ranidae 43
Scincidae 21
Testudinidae 1
Varanidae 5
Viperidae 17
TOTAL 559
3.3 Levels of herpetological diversity
The application of the Shannon index to the different herpetological taxa levels shows a
rise of herpetological diversity from north to south (Table 2). Here again, the low diversity in
the ecoregion AD probably results from the lower sampling effort in the ecoregion, however
the region displays several endemics that should be taken into account, such as Tarentola
chazaliae and Acanthodactylus aureus. For a small ecoregion, AD has a substantive number
of endemics, due to its particular characteristics like air humidity. The ecoregion SS was
found to have high species diversity, showing that the southern Sahara exhibits a remarkable
number of species. Such diversity can be influenced by the ecotone character of the
ecoregion, which is located in the transition from the Sahara to the Savannahs, and gathers
taxa from both ecoregions. Observed species richness in ecoregion SS was not very high
(Figure 20), therefore balanced relative abundances must have been the reason for such a high
Shannon index value. Naturally, diversity in terms of higher taxa levels is lower, meaning that

16. 15
the evolution mechanisms have been at work and permitted some radiation and speciation.
This is especially verified in the ecoregion SS, where species diversity is substantially higher
than genera diversity.
Table 2- Results of the application of the Shannon index in each ecoregion per species, genera and families. AD:
Atlantic Coastal Desert; NS: Northern Sahara Steppe and Woodlands; SS: Southern Sahara Steppe and
Woodlands; SA: Sahelian Acacia Savannah; and WS: West Sudanian Savannah.
AD NS SS SA WS
Shannon species 2.032 2.458 3.852 2.452 2.733
Shannon genera 1.496 1.785 1.921 1.988 2.419
Shannon families 1.496 1.536 1.543 1.777 2.207
3.4 Levels of niche breadth of amphibians and reptiles
Niche breadth was measured only in the 11 most sampled taxa (with 20 observations or
more), with a total of 390 observations. Almost all considered taxa have a substantial
proportion of presence in ecoregion SA (Figure 21). Tomopterna Cryptotis was the only taxon
to have been found only on one ecoregion and Acanthodactylus dumerili/senegalensis was the
only taxon to have been found in all ecoregions. Tarentola parvicarinata and Crocodylus
suchus seem to have a more or less balanced set of proportions of the ecoregions they inhabit
(Figure21).
Figure 21- Proportion of observations of the 11 most observed taxa in each ecoregion.
The Levin analysis (Table 3) highlighted Agama boueti and Tomopterna cryptotis as
having the lowest Bs values of the 11 taxa considered. A. boulengeri also exhibits a relatively

17. 16
low Bs having a higher sample size of 67 observations (Annex I). That suggests they are the
most selective in relation to habitat, having a small niche overlap. At the opposite side,
Tarentola parvicarinata displays higher Bs values, signifying that it should be a polyvalent
species that adapts to different environments, having a larger niche breadth. Also,
Acanthodactylus dumerili/senegalensis displays a relatively high Bs for a small sample size of
30 observations. A larger sample size probably would have resulted in even larger Bs, since it
is the only considered taxon which is present in the five ecoregions. These conclusions cannot
go without stressing the inherent sampling bias.
Table 3 – Standardized Levin’s index for selected amphibians and reptiles.
Standardized Levin's Bs
Acanthodactylus dumerili/senegalensis 0.286
Agama agama 0.226
Agama boulengeri 0.123
Agama boueti 0.057
Crocodylus suchus 0.233
Hoplobatrachus occipitalis? 0.209
Tarentola ephippiata 0.124
Tarentola parvicarinata 0.364
Tomopterna cryptotis 0.000
Troglodytes tripolitanus 0.264
Uromastyx dispar 0.261
3.5 Tarentola species distribution
The GIS analysis of Tarentola species observations (Figure 22) showed a pattern when put
against mean annual precipitation and temperature values (Figure 23). Although T. annularis
and T. chazaliae were both registered in areas with lower average temperature and annual
precipitation, the former was found mostly in higher altitude in ecoregions AD and NS while
the later was found only coastal areas of ecoregion AD. Apparently, the distribution of T.
parvicarinata is related with to temperature, living on areas with higher average temperature
of ecoregions SS, SA and WS. T. ephippiata exhibited the most plastic distribution, being
found in every ecoregion except for WS. The species is known from the later ecoregion
(Trapé et al., 2012), but it was not found during the present study. This fact seems to
contradict the Levin’s index results that indicated T. ephippiata had as displaying lower Bs

18. 17
than T. parvicarinata but the former exhibited major presence in ecoregion SA and residual
presences in other ecoregions whilst the later showed a more balanced set of presences along
ecoregions. T. ephippiata is a tree-dweller species (Trapé et al., 2012) and tree cover may be a
more limiting factor for it than precipitation or temperature. Also, competition with other
Tarentola species may have a strong importance. Although sympatry with T. parvicarinata
was not observed during this study, future field surveys should target this subject.
Figure 22 - Observations of species of Tarentola in the study area: T. chazaliae; T. annularis; T. ephippiata; T.
parvicarinata. AD: Atlantic Coastal Desert; NS: Northern Sahara Steppe and Woodlands; SS: Southern Sahara
Steppe and Woodlands; SA: Sahelian Acacia Savannah; and WS: West Sudanian Savannah.
The latitudinal gradients of temperature and precipitation were clearly observed but the
effects of proximity to the ocean and altitude could not be detected with this essay. Probably,
this is related to the under-sampling of ecoregion AD, in comparison to other ecoregions,
where we would have been expected a larger influence of the Atlantic Ocean in rainfall and
temperature. Unbiased studies, in term of sampling effort, are needed to better understand the
relationship of T. chazaliae with climatic factors.

19. 18
Figure 23- Observations of four Tarentola species in relation to annual average temperature and annual
precipitation variation of the locations.
4. CONCLUSIONS
Several conclusions can be drawn from the data collected: 1) fieldwork results are greatly
improved by the use of standard sampling techniques; 2) the obtained observational data have
inherent biases due to asymmetrical sampling efforts in each ecoregion; 3) herpetological
diversity at higher taxa levels increases from from north to south; and 4) considering only the
five ecoregions NS, AD, SS, SA and WS, Agama boueti, Agama boulengeri and Tomopterna
cryptotis have small niche breadth compared with Acanthodactylus dumerili/senegalensis and
Tarentola parvicarinata.
Closely related species can occupy different ecological niches, as seen with Tarentola
species in North-West Africa. Some species, such as T. parvicarinata are mostly well adapted
to hot temperatures, while T. chazaliae is apparently adapted to colder coastal areas, with
relatively high air humidity and low precipitation levels. Other species, such as T. annularis
thrive in the mountain ranges, where altitudinal compensation creates a refugee from the heat
and dryness of the desert. Climatic variables may not take the most relevant importance in the
case of the distribution of some species, as suggested for T. ephippiata.
20,0
22,0
24,0
26,0
28,0
30,0
32,0
0 200 400 600 800
Annualaveragetemperature(ºC)
Annual precipitation (mm)
T. annularis
T. chazaliae
T. ephippiata
T. parvicarinata

20. 19
Acknowledgments
Fieldwork was supported by a grant from National Geographic Society (Global Exploration
Fund; Grant GEFNE53-12). J.C. Brito, F. Martínez-Freiría, Z. Boratynski, D.V. Gonçalves,
J.C. Campos and the ANI crew (Association Nature Iniciative) for the companionship in the
journey, teaching and help with sampling. A. Sow, A. Araújo and FIBA for hosting. The
Biodeserts team (CIBIO/UP) for its integration. N. Ferrand for the search of internship.
5. BIBLIOGRAPHY
Brito J.C., Godinho R., Martínez-Freiría F., Pleguezuelos J.M., Rebelo H., Santos X., Vale
C.G., Velo-Antón G., Boratyński Z., Carvalho S.B., Ferreira S., Gonçalves D.V., Silva
T.L., Tarroso P., Campos J.C., Leite J.V., Nogueira J., Álvares F., Sillero N., Sow A.S.,
Fahd S., Crochet P.A., Carranza S. (2014) Unravelling Biodiversity, Evolution and
Threats to Conservation in the Sahara-Sahel. Biological Reviews 89: 215-231.
Gonzalez P., Tucker C.J., Sy H. (2012). Tree Density and Species Decline in the African
Sahel Attributable to Climate. Journal of Arid Environments 78: 55-64.
Hopkins B., White F. (1987). Vegetation Map of Africa. The Vegetation of Africa: A
Descriptive Memoir to Accompany the UNESCO/AETFAT/UNSO Vegetation Map of
Africa. The Journal of Ecology 75: 1214.
Dardel C., Kergoat L., Hiernaux P., Mougin E., Grippa M., Tucker C.J. (2014). Re-greening
Sahel: 30 years of Remote Sensing Data and Field Observations (Mali, Niger). Remote
Sensing of Environment 140: 350-364.
Fritzgerald L.A. (2012). Finding and Capturing Reptiles. In Reptile Biodiversity: Standard
Methods for Inventory and Monitoring. McDiarmid RW, ed. (Berkeley: University of
California), pp. 77-88.
García-Muñoz E., Sillero N. (2010) Two new types of noose for capturing herps. Acta
Herpetologica 5: 259-263.
Haslett J.R. (1990). Geographic Information Systems. A New Approach to Habitat Definition
and the Study of Distributions. Trends in Ecology & Evolution 5: 214-218.

21. 20
Herrmann, S.M., and Tappan G.G. (2013). Vegetation Impoverishment despite Greening: A
Case Study from Central Senegal. Journal of Arid Environments 90: 55-66.
Hijmans, R.J., Cameron S.E., Parra J.L., Jones P.G., Jarvis A. (2005). Very High Resolution
Interpolated Climate Surfaces for Global Land Areas. International Journal of
Climatology 25: 1965-1978.
Hoffmann A., Decher J., Rovero F., Schaer J., Voigt C., Wibbelt G. (1996). Field Methods
and Techniques for Monitoring Mammals. In Measuring and Monitoring Biological
Diversity: Standard Methods for Mammals. Wilson DE, (Washington, D.C.:
Smithsonian Institution), pp. 480-529.
Lambert, M.R.K. (1984). Amphibians and reptiles. In: Cloudsley-Thompson, J.L. (Ed.),
Sahara Desert, pp. 205–228. London: Pergamon Press. 348 pp.
Le Berre, M. (1989). Faune du Sahara 1–Poissons, Amphibiens et Reptiles. Lechevalier, R.
Chabaud, Paris.
Le Berre, M. (1990). Faune du Sahara. 2. Mammiferes. Lechevalier, R. Chabaud, Paris,
France.
Levins, R. (1968). Evolution in changing environments: Some theoretical explanations.
Princeton Univ. Press, Princeton, New Jersey. 120 p.
Le Houérou, H.N. (1997). Climate, Flora and Fauna Changes in the Sahara over the past 500
Million Years. Journal of Arid Environments 37: 619-647.
Le Houérou, H.N. (1992). Outline of the biological history of the Sahara. Journal of Arid
Environments, 22: 3–30.
Krebs, C.J. (1989) Similarity Coefficients and Cluster Analysis. In Ecological Methodology.
1st ed. (New York: Harper & Row), pp. 293-323.
Odjugo, A., Peter, O. Isi A.I. (2004). The Impact of Climate Change and Anthropogenic
Factors on Desertification in the Semi-arid Region of Nigeria. Global Journal of
Environmental Sciences 2: 118-127.
Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess,N.D., Powell G.V.N.,
Underwood, E.C., D’Amico J.A., Itoua, I., Strand, H. E., Morrison, J.C., Loucks, C.J.,
Allnut, T.F., Rickets, T.H., Kura, Y., Lamoureux, J.F., Wettengel, W.W.W., Hedao P.,
Kassem, K.R. (2001). Terrestrial Ecoregions of the World: A New Map of Life on
Earth. BioScience 51: 933-938.

22. 21
Popov, G.B., Duranton, J.F. & Gigault, J. (1991). Etude Ecologique des Biotopes du Criquet
P`elerin Schistocerca gregaria (Forsskal, 1875) en Afrique Nord-occidentale.
Montpellier: PRIFAS,GERDAT. 743 pp.
Pimm, S.L. (2008) Biodiversity: climate change or habitat loss-which will kill more species?
Current Biology 18: R117-R119.
Riddle, B.R., M. N. Dawson, E.A. Hadly, D.J. Hafner, M.J. Hickerson, S.J. Mantooth, Yoder,
A.D. (2008). The Role of Molecular Genetics in Sculpting the Future of Integrative
Biogeography. Progress in Physical Geography 32: 173-202.
Sayre, R., P. Comer, J. Hak, C. Josse, J. Bow, H. Warner, M. Larwanou, E. Kelbessa, T.
Bekele, H. Kehl, R. Amena, R. Andriamasimanana, T. Ba, L. Benson, T. Boucher, M.
Brown, J. Cress, O. Dassering, B. Friesen, F. Gachathi, S. Houcine, M. Keita, E.
Khamala, D. Marangu, F. Mokua, B. Morou, L. Mucina, S. Mugisha, E. Mwavu, M.
Rutherford, P. Sanou, S. Syampungani, B. Tomor, A. Vall, J. Vande Weghe, E.
Wangui, L. Waruingi. (2013) A New Map of Standardized Terrestrial Ecosystems of
Africa. Washington, DC: Association of American Geographers. 24 pages.
Trape, J.F., Trape, S. Chirio, L. (2012) Lézards, crocodiles et tortues d'Afrique occidentale et
du Sahara. IRD Editions, Marseille.
Wilms, T., Wagner, P., Geniez, P., Mateo, J.A., Joger, U., Pleguezuelos, J., Slimani, T., El
Mouden, E.H. (2013) Tarentola chazaliae. In: IUCN 2013. IUCN Red List of
Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 May
2014.

23. 22
ANNEXES
Annex I – Number of observations of amphibians and reptiles.
Class Family Taxa N
Amphibia 59
Bufonidae 13
Bufo viridis 1
Bufo xeros 12
Ptychadenidae 3
Ptychadena sp. 3
Ranidae 43
Hoplobatrachus occipitalis 20
Hoplobatrachus sp. nov. 3
Tomopterna cryptotis 20
Reptilia 504
Agamidae 158
Agama agama 36
Agama boueti 20
Agama boulengeri 67
Agama sankaranica 1
Trapelus boehmei 7
Uromastyx dispar 27
Boidae 2
Python sebae 2
Chamaeleonidae 1
Chamaeleo africanus 1
Colubridae 20
Hemorrhois dorri 2
Lytorhynchus diadema 4
Psammophis elegans 1
Psammophis schokari 6
Psammophis sibilans 6
Telescopus tripolitanus 1
Crocodylidae 27
Crocodylus suchus 27
Gekkonidae 62
Hemidactylus angulatus 6
Stenodactylus mauritanicus 9
Stenodactylus petrii 4
Stenodactylus sthenodactylus 4
Tropiocolotes tripolitanus 38
Lacertidae 67
Acanthodactylus aureus 15
Acanthodactylus dumerili/senegalensis 30
Acanthodactylus longipes 19

24. 23
Mesalina olivieri 1
Mesalina rubropunctata 1
Phyllodactylidae 123
Tarentola annularis 10
Tarentola chazaliae 6
Tarentola ephippiata 30
Tarentola parvicarinata 75
Scincidae 21
Chalcides delislei 1
Chalcides sphenopsiformis 2
Trachylepis affinis 2
Trachylepis perrotetii 6
Trachylepis quinquetaeniata 10
Testudinidae 1
Geochelone sulcata 1
Varanidae 5
Varanus exanthematicus 1
Varanus griseus 2
Varanus niloticus 2
Viperidae 17
Cerastes cerastes 1
Echis leucogaster 13
Echis ocellatus 3
TOTAL 559
Annex II- Entries in the personal diary of the trip.
Dia 30 27/01/14
A viagem já começou há 30 dias, mas parece que já começou há dois ou três meses. Só a
memória dos primeiros dias da viagem já parece ter sido de há uma vida atrás, quanto mais as
distantes memórias do antes da viagem. Absorvo tudo, memorizo cada minuto do que
acontece, tal é a novidade de tudo!
O tempo passa devagar, os dias são longos e belos. As saudades das pessoas que amo são
uma constante cuja subtileza foi refinada pela habituação. Tenho as saudades guardadas num
baú que não consigo fechar, mas onde pelo menos estão guardadas e não transbordam.
Permite-me viver um dia de cada vez sem grandes ansiedades.
Dia 38 04/02/2014
Tenho fome. O sabor a cebola que me fica na boca depois das refeições já enjoa. Sobretudo
quando andamos muitas horas seguidas de carro. (…) Vou dormir, isto de deitar tarde e
acordar cedo também tem o seu impacto no corpo.