Spatial patterns of genetic variation provide information central to many ecological, evolutionary, and conservation questions. This spatial variability has traditionally been analyzed through summary statistics between pairs of populations, therefore missing the simultaneous influence of all populations. More recently, a network approach has been advocated to overcome these limitations. This network approach has been applied to a few cases limited to a single species at a time. The question remains whether similar patterns of spatial genetic variation and similar functional roles for specific patches are obtained for different species. Here we study the networks of genetic variation of four Mediterranean woody plant species inhabiting the same habitat patches in a highly fragmented forest mosaic in Southern Spain. Three of the four species show a similar pattern of genetic variation with well-defined modules or groups of patches holding genetically similar populations. These modules can be thought of as the long-sought-after, evolutionarily significant units or management units. The importance of each patch for the cohesion of the entire network, though, is quite different across species. This variation creates a tremendous challenge for the prioritization of patches to conserve the genetic variation of multispecies assemblages.complex networks | gene flow | habitat fragmentation | population genetics

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Helianthemum is the largest, most widely distributed and most taxonomically complex genus of the Cistaceae. To examine the intrageneric phylogenetic relationships in Helianthemum, we used sequence data from plastid DNA (ndhF, psbA-trnH, trnL-trnF) and the nuclear ITS region. The ingroup consisted of 95 species and subspecies (2 subgenera, 10 sections) from throughout the range of Helianthemum, while the outgroup was composed of 30 species representing all the genera in the Cistaceae (Cistus Crocanthemum, Fumana, Halimium, Hudsonia, Lechea, Tuberaria) plus Anisoptera thurifera subsp. polyandra (Dipterocarpaceae). To infer phylogenetic relationships, we analysed three different matrices (cpDNA, nrDNA, cpDNA + nrDNA concatenated) using maximum likelihood and Bayesian inference, and performed molecular dating to estimate the ages of origin of the main clades using a Bayesian approach. The cpDNA + nrDNA concatenated dataset provided the highest Bayesian posterior probabilities and bootstrap support values, and the results supported the monophyly of the genus Helianthemum and its sister relationship to a clade consisting of all species of Cistus, Crocanthemum, Halimium, Hudsonia and Tuberaria. This result means that we did not retrieve the sister relationship between Helianthemum and Crocanthemum (plus Hudsonia) that could be expected according to previous published studies. Despite their different statistical support, the topology of the inner branches of all the consensus trees showed that Helianthemum is characterized by the emergence of three major clades in agreement with above-species taxonomy, although unresolved polytomies still remain towards the tips of the trees (species and subspecies). Clade I (mainly distributed in Mediterranean and alpine environments in European and western Asiatic mountain chains) fully coincided with subg. Plectolobum, whereas subg. Helianthemum was retrieved in clade II (arid and semi-arid environments from Macaronesia, the Mediterranean, subtropical northern Africa, Anatolia and central Asia) and clade III (Mediterranean ecosystems around the Mediterranean Basin). The burst of diversification during the Plio-Pleistocene detected in the three main clades of Helianthemum is concomitant with the Messinian salinity crisis, the onset of Mediterranean climatic conditions, and Quaternary glaciations, as found in many other groups of Mediterranean plants. Thus, the general lack of resolution in the trees can be attributed to rapid species diversification and events of reticulate evolution. A series of further taxonomic and evolutionary inferences can be drawn from our analyses: (i) no species occupied an early-diverging position with regard the rest of the species; (ii) a close relationship between H. caput-felis and subg. Plectolobum; (iii) an unexpected close relationship between H. squamatum/ H. syriacum (and H. motae), H. lunulatum/ H. pomeridianum and among H. songaricum/ H. antitauricum/ H. germanicopolitanum; (iv) a close relationship between incertae sedis species and sect. Eri...

Landscape fragmentation is ancient and severe in the countryside of the Guadalquivir river valley (Western Andalusia, Southern Spain). BIANDOCC is a project that aims to inventory all the forest patches embedded in this anthropogenic area to record quantitative, qualitative, and descriptive information about management, conservation status, vegetation physiognomy and Xoristic richness. We have characterized a 'relictual' landscape (t1% of habitat retention) where nearly 70% of the patches (N = 535) are owned by private landowners who manage them to harvest pine nuts, cork, and Wrewood, for coal making, cattle raising, and to a lesser extent, beekeeping and agriculture. The publicly owned patches are intensively used for recreation. As a consequence, the vegetation physiognomy and conservation status in most forest stands is impoverished, with low shrub diversity and coverage and none or very low natural tree regeneration. Furthermore, patch size, connectedness and patch fractal dimension (i.e. microhabitat diversity) are all very low. However, the botanic richness is worth mentioning: 1,032 plant taxa have been identiWed, of which 70 are catalogued in an oYcial red list, 39 are relevant chorological novelties, and one was newly described for science. Therefore, and interestingly, the remnant forest patches in the studied area can be regarded as relevant biodiversity reservoirs. The project reported here constitutes an important baseline for developing true conservation action plans and provides an opportunity to address the potential ecological and biological eVects of fragmentation to plant genes, species, populations and communities, at the regional scale of the study, which are enhanced by the emergent landscape genetics and landscape ecology analytical tools.

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Summary1. The long-term persistence of fragmented plant populations is predicted to be threatened by a loss of genetic variability and increasing inbreeding, which might lower offspring fitness through inbreeding depression. Assessing plant progeny performance together with measurements of genetic diversity and mating patterns is therefore essential in the understanding of the role of the historical (i.e. genetic diversity in adults) and contemporary (i.e. current mating patterns) genetic effects of fragmentation on inbreeding depression, thus, on recruitment potential. 2. We evaluated genetic diversity, mating patterns and progeny performance at different life stages in seven populations of a Mediterranean shrub (myrtle Myrtus communis) that differed in size and degree of isolation (Large, Small-connected and Small-isolated populations). The study was conducted in the Guadalquivir Valley (SW Spain), a chronically and severely fragmented landscape characterized by c. 1% of woodland cover. 3. Parameters of genetic diversity (A r , H o and H e ) of adult plants were in general higher in the Large populations than in the two types of Small populations, which were similar. Outcrossing rates were higher in Small-connected populations (mean: t m = 0AE62), intermediate in Large (t m = 0AE35) and lower in Small-isolated populations (t m = 0AE13), and were positively correlated with the genetic diversity of progenies. 4. Several measurements of progeny performance were higher in Small-connected populations, intermediate in Large and lower in Small-isolated populations, in particular those related with the quantity of viable seedlings produced (germination and survival). Outcrossing rates rather than the genetic diversity of adult plants were positively correlated with these measurements of progeny performance. 5. We thus conclude that contemporary mating patterns (outcrossing rates) have a more critical influence on progeny performance than either population fragmentation or the historical levels of genetic diversity. 6. Synthesis and applications. It may be possible to enhance either the fitness or certain levels of genetic diversity in progenies by promoting outcrossed matings in fragmented populations of selfcompatible plant species. In our study species, this would be feasible either by controlling honeybee Apis mellifera hives or maintaining and ⁄ or enhancing landscape connectivity around small patches.

Systematic and evolutionary relationships within the diploid Western Mediterranean Phlomis crinita/lychnitis complex remain controversial apparently due to hybridization and introgression. This study examines patterns of sequence variation in the nuclear ribosomal DNA (ITS region) and three non‐coding plastid DNA regions (trnH‐psbA, trnT‐trnL and atpB‐rbcL) in this complex in an aim to clarify whether hybridization, introgression or lineage sorting resulting from recent diversification is mainly responsible for poorly understood relationships. Information recovered from nuclear and chloroplast markers was found to be strongly incongruent. Phylogenetic analysis of inferred nuclear ITS ribotypes is consistent with previous morphometric and taxonomic results in distinguishing two sister lineages, P. crinita s.l. and P. lychnitis. In addition, the high number of additive polymorphisms detected in ITS sequences suggests the sharing of ancestral variability and local patterns of gene flow within the complex. In contrast, the pattern of chloroplast haplotype variation is geographic rather than taxonomic, which might be caused by low mutation rates combined with frequent instances of interspecific hybridization. To integrate the apparently discordant plastid and nuclear evidence, we suggest that both lineage sorting and horizontal transfer have been involved. Even though pinpointing cases due to either phenomenon is difficult, the available data provide evidence of two sister lineages where hybridization events can be identified despite the inheritance of ancestral polymorphisms.

Aim  The effect of habitat fragmentation on population genetic structure results from the interaction between species’ life history traits and the particular landscape context, and both components are inherently difficult to tease apart. Here, we compare the genetic (allozyme) structure of four co‐occurring woody species with contrasting life histories to explore how well their response to the same fragmentation process can be predicted from their functional traits. Location  A highly fragmented forest landscape located in the lower Guadalquivir catchment, south‐western Spain. Methods  We sampled four species (Cistus salviifolius, Myrtus communis, Pistacia lentiscus and Quercus coccifera) from the same 23 forest fragments known to form a representative array of habitat characteristics in the region. We assessed genetic diversity (A, He and Ng) and differentiation (FIS and FST) for each species and explored their potential drivers using a model‐selection approach with four fragment features (size, historical and current connectivity, and stability) as predictor variables. Results  Regional‐scale genetic diversity increased from the shortest‐lived to the longest‐lived species, while population differentiation of the self‐compatible species was roughly double that of the three self‐incompatible species. Fragment size was the only feature that did not consistently affect the genetic diversity of local populations across all species. Three species showed signs of being affected by fragmentation, yet each responded differently to the set of fragment features considered. We observed several trends that were at odds with simple life history‐based predictions but could arise from patterns of gene flow and/or local‐scale demographic processes. Main conclusions  Our comparative study of various landscape features and species underscores that the same fragmentation process can have very different, and complex, consequences for the population genetic structure of plants. This idiosyncrasy renders generalizations across natural systems very difficult and highlights the need of context‐oriented guidelines for an efficient conservation management of species‐rich landscapes.