Juan M. Pleguezuelos

Unravelling biodiversity, evolution and threats to conservation in the Sahara‐Sahel

Deserts and arid regions are generally perceived as bare and rather homogeneous areas of low diversity. The Sahara is the largest warm desert in the world and together with the arid Sahel displays high topographical and climatic heterogeneity, and has experienced recent and strong climatic oscillations that have greatly shifted biodiversity distribution and community composition. The large size, remoteness and long‐term political instability of the Sahara‐Sahel, have limited knowledge on its biodiversity. However, over the last decade, there have been an increasing number of published scientific studies based on modern geomatic and molecular tools, and broad sampling of taxa of these regions. This review tracks trends in knowledge about biodiversity patterns, processes and threats across the Sahara‐Sahel, and anticipates needs for biodiversity research and conservation. Recent studies are changing completely the perception of regional biodiversity patterns. Instead of relatively low species diversity with distribution covering most of the region, studies now suggest a high rate of endemism and larger number of species, with much narrower and fragmented ranges, frequently limited to micro‐hotspots of biodiversity. Molecular‐based studies are also unravelling cryptic diversity associated with mountains, which together with recent distribution atlases, allows identifying integrative biogeographic patterns in biodiversity distribution. Mapping of multivariate environmental variation (at 1 km × 1 km resolution) of the region illustrates main biogeographical features of the Sahara‐Sahel and supports recently hypothesised dispersal corridors and refugia. Micro‐scale water‐features present mostly in mountains have been associated with local biodiversity hotspots. However, the distribution of available data on vertebrates highlights current knowledge gaps that still apply to a large proportion of the Sahara‐Sahel. Current research is providing insights into key evolutionary and ecological processes, including causes and timing of radiation and divergence for multiple taxa, and associating the onset of the Sahara with diversification processes for low‐mobility vertebrates. Examples of phylogeographic patterns are showing the importance of allopatric speciation in the Sahara‐Sahel, and this review presents a synthetic overview of the most commonly hypothesised diversification mechanisms. Studies are also stressing that biodiversity is threatened by increasing human activities in the region, including overhunting and natural resources prospection, and in the future by predicted global warming. A representation of areas of conflict, landmines, and natural resources extraction illustrates how human activities and regional insecurity are hampering biodiversity research and conservation. Although there are still numerous knowledge gaps for the optimised conservation of biodiversity in the region, a set of research priorities is provided to identify the framework data needed to support regional conservation planning.

Influence of prey densities in the distribution and breeding success of Bonelli's eagle (Hieraaetus fasciatus) : Management implications

Diet, prey availability, and breeding success were studied in a population of Bonellis eagle (Hieraaetus fasciatus) in the province of Granada, SE Spain. The densities of the main prey species, European wild rabbit (Oryctolagus cuniculus), red-legged partridge (Alectoris rufa), wood pigeon (Columba palumbus), and rock dove (Columba livia), representing 90.2% of the biomass, were analysed in 19 territories occupied by pairs of Bonellis eagles and 15 potential territories that were unoccupied but appropriate for nesting. We found no significant differences in prey density between the two types of territories. Contrary to other raptor species, we found no significant relationship between the density of their main prey species and the distance of the neighbouring pairs, either between that density and breeding success. These findings, together with the prior knowledge of nest-site selection of this eagle in the study area, can be used for proper planning of conservation strategies. These should avoid unnecessary effort to increase the eagles food supply, and should promote the reintroduction of individuals to suitable sites for Bonellis eagle.

Prey and prey-size selection by the short-toed eagle ( Circaetus gallicus ) during the breeding season in Granada (south-eastern Spain)

The diet of the short-toed eagle ( Circaetus gallicus ) was studied during the breeding season by analysing pellets and remains generated by adults and nestlings. The raptor proved to be a specialist feeder, as snake prey comprised almost 95% of the diet, in both frequency and biomass. We gathered information on prey availability and prey size availability (1499 specimens of nine different species) by searching for snakes in the study area. Regressions of vertebra centrum length and dorsal-scale length on snout–vent length (SVL) of the snakes were used to calculate prey size. The taxonomic diet composition differed depending on the sample analysed – remains or pellets – but we failed to find between-year diet differences. Most of the snakes identified (140 out of 141) belonged to only three species, Malpolon monspessulanus , Elaphe scalaris , and Coluber hippocrepis . Other prey included Lacerta lepida , Natrix maura , Bufo bufo , and Alectoris rufa , and many secondary prey (prey from stomach of the prey) were also detected in the pellets. The three main prey species were consumed according to their availability in the study area, but the eagles selected on the basis of prey size. Large snakes within 700–1000 mm SVL were positively selected, whereas snakes under 600 mm SVL were negatively selected. Adult eagles consumed the same prey species as those carried to the nest to feed their single nestling, although prey given to nestlings proved larger in size and biomass, suggesting that adults consumed the smallest prey, reserving the largest for nestlings.

Food availability induces geographic variation in reproductive timing of an aquatic oviparous snake (Natrix maura)

The viperine snake Natrix maura is a common water snake, which forages on aquatic prey such as fish and frogs in Western Mediterranean water bodies. Female viperine snakes collected from three populations at the Iberian Peninsula during the vitellogenesis period were compared. Mean clutch size and range, as well as the slope of the regression between body size and clutch size, did not show differences between populations. In contrast, mean size of enlarged follicles of females collected in May from the Ebro Delta proved significantly smaller than those of females from the Matarranya River (50 km far) and the Granada Depression (500 km far). There were no differences in climatic conditions between areas. However, seasonal variation in food availability was significantly different in the Ebro Delta. In this area, the rice fields are dry in early spring as men control the water flow, and prey are not available. This energetic constraint induced female viperine snakes to adjust reproductive timing according to seasonal availability and to delay vitellogenesis for at least one month. By contrast, other Mediterranean populations exhibited a rather high prey availability from early spring (e.g. Matarranya River), females being in good condition in this season and consequently vitellogenesis starting earlier than in the Ebro Delta. This study illustrates a new case of reproductive plasticity in snakes.

Deep evolutionary lineages in a Western Mediterranean snake (Vipera latastei/monticola group) and high genetic structuring in Southern Iberian populations.

Phylogeographic studies during the last decade confirmed an internal complexity of the Iberian Peninsula and northern Maghreb as refugial areas during the Miocene to Pleistocene period. Species with low vagility that experienced the complex climatic and palaeogeographic processes occurred in the Western Mediterranean Basin are excellent candidates to study the extent of lineage diversification in this region. We applied phylogenetic analyses based on mitochondrial data to infer the evolutionary history of Vipera latastei/monticola and identify the major biogeographic events structuring the genetic diversity within this group. We obtained a well-resolved phylogeny, with four highly divergent lineages (one African and three Iberian) that originated in the Tertiary. Coalescence-based estimations suggest that the differentiation of the four major lineages in V. latastei/monticola corresponds to the Messinian salinity crisis and the reopening of the Strait of Gibraltar during the Miocene. Subsequent Pliocene and Pleistocene climatic oscillations continued to isolate both Iberian and Maghrebian populations and led to a high genetic structuring in this group, particularly in Southern Iberia, a complex palaeogeographic and topographic region with high endemism levels. This study does not support the current taxonomy of the group, thus suggesting that an integrative evaluation of Iberian and African populations is needed to resolve its systematics.

Sexual Dimorphism and Sexing of Mediterranean Colubrids Based on External Characteristics

Sexual dimorphism was studied in seven colubrid species living in the Mediterranean area of the Iberian Peninsula. Six variables of external morphology were considered: numbers of ventral and subcaudal scales, snout-vent and tail lengths, body and tail surface in a cross section close to the vent, and certain ratios of these variables. To determine which traits enable us to distinguish between the sexes, we used a stepwise discriminant analysis. The ventral and subcaudal scales, because their numbers are fixed at birth, were the best predictors of the sex of a randomly-chosen specimen. Using the number of ventral scales and certain ratios, we correctly identified the sex in all individuals of Elaphe scalaris and Natrix maura, nearly 100% of the individuals of Coluber hippocrepis and Natrix natrix, and almost 95% of Coronella girondica and Macroprotodon cucullatus. The method did not work with Malpolon mon- spessulanus, which is sexually monomorphic in the characteristics used here.

Northward shifts of the distributions of Spanish reptiles in association with climate change.

It is predicted that climate change will drive extinctions of some reptiles and that the number of these extinctions will depend on whether reptiles are able to change their distribution. Whether the latitudinal distribution of reptiles may change in response to increases in temperature is unknown. We used data on reptile distributions collected during the 20th century to analyze whether changes in the distributions of reptiles in Spain are associated with increases in temperature. We controlled for biases in sampling effort and found a mean, statistically significant, northward shift of the northern extent of reptile distributions of about 15.2 km from 1940-1975 to 1991-2005. The southern extent of the distributions did not change significantly. Thus, our results suggest that the latitudinal distributions of reptiles may be changing in response to climate change.

Habitat selection of the common chameleon (Chamaeleo chamaeleon) (L.) in an area under development in southern Spain: implications for conservation

We studied the features of the habitat selection of the common chameleon [Chamaeleo chamaeleon (L.)] in a population located in an area under development in south-eastern Spain. Chameleons were recorded in zones characterised by the presence of roads, lack of natural vegetation and presence of cultivation at the macrohabitat level, and tree-dominated vegetation and bare soils at the microhabitat level. This particular habitat selection increases the propensity for casualties due to illegal collection, accidental road deaths or nest losses because of ploughing. However, chameleons were not present in nearby natural environments in which these sources of mortality are much less intense or absent. We suggest that the sustainability of chameleon populations requires a combination of maintaining traditional human land uses and the adoption of preventive measures, such as road barriers in some selected sites or the protection of safe sites for nesting, since both the more aggressive human pressures (settlements for tourism) and the promotion of natural landscapes (reforestation) could be negative for the species.

Setting conservation priorities for the Moroccan herpetofauna: the utility of regional red lists.

We assess the national conservation status of the amphibians and reptiles of Morocco by applying the IUCN Red List Criteria at the national level and assess its utility as a planning tool to establish regional priorities for conservation. We rely on the accessory data accompanying regional red lists, mainly distribution range and habitats used by, and threats affecting, species of conservation concern. We also correlated some natural history traits to examine the nature and causes of the risk of extinction. With 13 species of amphibians (31% regionally threatened) and 99 species of reptiles (14% regionally threatened), Morocco is one of the Mediterranean countries with the highest diversity of herpetofauna, mainly because of the high percentage of endemism (amphibians 31%, reptiles 24%). The relative frequencies of threatened species were found to be contingent on both taxonomic group and habitat. The overwhelming importance of the threats of small range and number of habitats used by species is different from the threats to the same species at the global level; this demonstrates the usefulness of national or regional analyses of conservation status for setting conservation priorities. The importance of regional assessment derives from the fact that the boundaries set for conservation management are mainly political rather than biogeographical.

REPRODUCTIVE ECOLOGY OF THE HORSESHOE WHIP SNAKE (COLUBER HIPPOCREPIS) IN THE IBERIAN PENINSULA

-Data on the reproductive ecology of the Horseshoe whip snake (Coluber hippocrepis) are scarce and largely anecdotal in northern Mediterranean populations of this species. Dissections of preserved specimens from the southeast of the Iberian Peninsula, together with field observations, provided information on size at sexual maturity, reproductive and fat body cycling, clutch size, hatching period, and feeding frequency. Males attain sexual maturity at about 500 mm snout-vent length (SVL) and females at 680 mm SVL. As with populations from Northern Africa, males exhibit a prenuptial spermatogenic cycle. The complete reproductive cycle (spermatogenesis, vitellogenesis, mating, shelling, oviposition, incubation, and hatching) occurs within the same calendar year. The northern limit of this spermatogenic cycle also coincides with the northern limit of the distribution of the species. The female reproductive cycle is seasonal, and most sexually mature females reproduce annually. Vitellogenesis is associated with a decline in the fat body level. Oviposition occurs in late June to early July, the mean clutch size is 6.8 eggs, and there is a significant correlation between female size and fecundity. Females feed rarely when gravid. The hatching period begins in late August and lasts to mid-September. Offspring size was 237 to 308 mm SVL, and offspring mass 6.1 to 9.0 g. The reproductive biology of snakes is less well understood than that of any other reptilian group except the crocodilians (Seigel and Ford, 1987). In the Western Palearctic region, most of the studies on reproductive biology of snakes have focused on viperids (Volsoe, 1944; Nilson, 1981; Saint Girons and Duguy, 1992) or colubrids from northern and central Europe (Bourliere and Petter-Rouseaux, 1955; Goodar and Spellerberg, 1980; Naulleau, 1992; Luiselli et al., 1996, 1997), and there are few studies on species inhabiting Mediterranean habitats (but see e reproductive biol gy of snakes is less ll understo d than that of any other r ptilian up except the croc dilians (Seig l and Ford, 7). In the Western Pale rcti region, most of studies on reproductive biology of snakes e focused on viperids (Vols e, 1944; Nilson, 1; Saint Girons and Dug y, 1992) or c lui s from northern and central Europe (BourCheylan et al., 1981; Hailey and Davies, 1987; Agrimi and Luiselli, 1994). Coluber hippocrepis is a long and slender-bodied colubrid, with a total length of up to 1800 mm, and no sexual dimorphism in body size (Feriche et al., 1993). It is found in a variety of warm Mediterranean habitats throughout northern Tunisia and Algeria, most regions of Morocco, and the eastern and southern half of the Iberian Peninsula. The populations inhabiting the Iberian Peninsula have been isolated from the original populations in North Africa since la et al., 1981; Hailey and Davies, 1987; i i and Luiselli, 1 94). hippocrepis is a long and slender-bodl brid, with a tota length of up to 1800 a d no sexual dimorphism in body size i e et al., 1 93). It is found in a variety of editerranean habitats throughout northisia and Algeria, most regions of Mo, a d the eastern and southern half of the i Peninsula. The populations inhabiting 202 This content downloaded from 207.46.13.83 on Sun, 23 Oct 2016 05:04:44 UTC All use subject to http://about.jstor.org/terms REPRODUCTIVE ECOLOGY OF COLUBER HIPPOCREPIS the formation of the Strait of Gibraltar, approximately 5.3 x 106 yr (Busack, 1986; B. Sanchiz, pers. cor.). Although the distribution of the species in southern Europe suggests that males should retain the spermatogenic prenuptial cycle exhibited by the specimens from Morocco (Bons, 1967; Pozuelo, 1974; Saint Girons, 1982), the reproductive biology of the populations from the northern Mediterranean Basin has not