Exploring the effect of host tree identity on epiphyte bryophyte communities in different Canarian subtropical cloud forests

This study explores the host tree preferences of epiphyte bryophyte communities in two key types of evergreen cloud forests on La Gomera (Canary Islands, Spain): ericaceous versus broadleaved laurel forest. By comparing two pairs of tree species (Erica arborea and Myrica faya vs. Ilex canariensis and Laurus novocanariensis) that occur in both forest types, we quantitatively examined whether epiphyte-host relationships change with the type of forest. In 51 ancient forest stands, the low-trunk bryophyte composition on the two host tree groups was analysed with both non-parametric procedures and ordination analyses. Our results highlight that the influence of local environmental conditions on the structuring of epiphyte communities may be different depending on the host tree identity. Whilst the epiphyte composition of the host tree group formed by I. canariensis and L. novocanariensis differed significantly between forest types depending on solar exposure, we failed to find variations for the other host tree group, excepting in those localities wherein mist precipitation was extremely high. Our findings highlight the importance of the natural diversity of tree species along environmental gradients, as well as of water availability at different spatial scales for epiphytic bryophytes in montane cloud forests.     

Genetic differentiation of Albizia lebbeck (L.) Benth. populations estimated by RAPD and ISSR markers

Abstract

Albizia lebbeck (L.) Benth., a popular multi‐purpose legume tree species, has a wide distribution throughout the Indian subcontinent. The species is highly valued for its quality timber, gum yield and therapeutical uses. However, the increasing social and economical pressures are devastating the natural stands of A. lebbeck forests. So, there is a need to estimate the genetic variation present in A. lebbeck populations. Both RAPD and ISSR molecular markers were used to analyse 172 individuals representing eight populations of the species in different geographical range. The within‐population genetic diversity ranged from 1.23 to 1.38. The total gene variability was 0.34 of which 0.17 (50%) accounted for within‐population gene variability. The genetic differentiation between populations (Gst = 0.49) was significantly correlated to geographical distance (r = 0.61, p < 0.001). An UPGMA clustering suggests a high level of genetic isolation due to distance. This study revealed the genetic differentiation which will provide a template for adaptation and evolution of the populations and species.     

Genetic differentiation of the Thorn‐tailed Rayadito Aphrastura spinicauda (Furnariidae: Passeriformes) revealed by ISSR profiles suggests multiple palaeorefugia and high recurrent gene flow

Nucleotide sequence data (cytochrome b) and ISSR genomic fingerprints were used to analyse the genetic variation and population differentiation in Thorn‐tailed Rayadito, a widespread Patagonian forest bird. We included samples from eight populations of Thorn‐tailed Rayadito covering most of the distribution range of the species: from fragmented patches of Olivillo forest in northern Chile to Isla Navarino forests in the extreme south of South America. Low levels of genetic diversity were found among populations, with a large within‐population molecular variance indicating high levels of gene flow. The multivariate and cluster analyses based on ISSR markers show that the subspecies bullocki (from Mocha Island) differs significantly from all other populations. The subspecies fulva (Chiloé Island) shows less differentiation than bullocki, sharing several alleles with continental populations. Bayesian analyses suggest that the Mocha Island population contributes most to the total genetic diversity observed in the species. Mantel tests revealed no significant correlation between geographical distance and pairwise genetic distance and cytochrome b sequence analyses failed to detect differentiation among subspecies. Mocha Island might have been a palaeorefuge and this population may have diversified by genetic drift after the last glacial maximum. There is also the possibility of a postglacial colonization of the Thorn‐tailed Rayadito from an austral palaeorefugium, supporting a multiple refugia hypothesis. This study illustrates the usefulness of the rarely used ISSR genomic fingerprint method in avian phylogeography.     

Genetic diversity and genetic structure of Decalobanthus boisianus in Hainan Island,China

Decalobanthus boisianus is a native plant of Hainan Island, China, which has caused considerable damage to tropical forest ecosystems in recent decades. Understanding the genetic diversity and structure of this species can facilitate uncovering the molecular mechanism of its invasive ability. Here, we collected 77 individuals of D. boisianus spanning 8 distribution areas with a gradient of human disturbance intensity (i.e., low, moderate, and high disturbance intensity groups) to assess patterns of genetic diversity and structure using inter simple sequence repeat (ISSR) markers. We found that a total of 220 loci were scored with 13 primers using ISSR methods, and that 198 loci were polymorphic. The genetic diversity of D. boisianus among these eight forests decreased with increasing human disturbance intensity. Over 70% of the total genetic variation was present within populations, while less than 30% of variation was found among populations. There was a high gene flow (1.27) among them due to a lack of effective geographic barriers. The mean Nei's genetic distance of D. boisianus populations was found to be relatively small (i.e., 0.07), and the average genetic similarity of the eight populations was high (i.e., 0.93). Our findings indicate that the genetic diversity of D. boisianus correlated to human disturbance density, and that D. boisianus populations in Hainan Island have frequent gene exchange. We suggest that reduce deforestation to decrease human disturbance may be a good way to prevent the invasion of D. boisianus.     

Persistence of genetic variation in recolonized Tsuga canadensis (Eastern hemlock) populations following historic forest clearance

The recovery of genetic variation in newly recolonized populations is an important concern in forest conservation genetics. We examined the potential recovery of genetic diversity and changes to genetic structure in populations of the wind‐pollinated species Tsuga canadensis that naturally regenerated following the extensive 19th century regional forest clearance for agriculture in west‐central Massachusetts. We genotyped 264 individuals across six microsatellite loci and compared levels and patterns of genetic variation between primary forests (forests that were logged but never cleared) and secondary forests (stands that were recolonized following agricultural abandonment). We found no significant reductions in genetic diversity in secondary forests (A_R = 5.450; H_S = 0.718) compared to primary forests (A_R = 5.742; H_S = 0.730). Moreover, the population genetic differentiation was also not significantly reduced in secondary compared to primary forests, with no significant genetic structure observed among all populations. These results suggest rapid genetic recovery of T. canadensis populations in recolonized forests compared with other late‐successional temperate tree species.     

Clonal distribution,fertility and sex ratios of the moss Plagiomnium affine (Bland.) T.Kop. in forests of contrasting age

Abstract

Six populations of the clonal forest floor moss Plagiomnium affine from forests of different age were screened for genetic variation at 23 allozyme loci, of which nine were polymorphic. Samples consisting of two adjacent unconnected shoots were taken at regular intervals along one transect from each population. A total of 602 shoots was analysed. Almost 80% of the shoots were sterile (i.e. not expressing male or female gender). Sex remained unknown for only 10% of shoots after identification of genets based on electrophoretic data. We identified a mean number of 3.7 fertile clones per population. The mean length of clones along transects in each population ranged between 2 and 3 m. The size distribution within populations was bimodal, with a few dominant clones and a varying number of much smaller clones. The overall sex ratio was slightly female biased at the ramet level, but balanced at the genet level. Forest age was negatively correlated with percentage of sterile shoots and positively correlated with frequency of sporophytes. In both cases correlations were significant only if population 1, which was subject to extreme soil disturbance by badgers, was excluded. We conclude that the effective population size is larger, and the susceptibility to genetic drift is lower, in old forests.     

Genetic variation in the liverwort Bazzania trilobata inferred from ISSR markers

Abstract

The distribution of Bazzania trilobata in Poland coincides with two parts of the natural distribution range of Norway spruce: the mountains of southern Poland and the northeastern lowlands. The occurrence of this species is connected with primeval forest communities and it was recognized as a relict of them. Genetic variation of 10 populations of B. trilobata from two different regions of Poland (lowlands and mountains) was studied in order to establish the genetic structure of this species and to compare the level of genetic variation within and among populations originating from primeval and managed forests. An analysis based on polymorphic inter-simple sequence repeat (ISSR) loci revealed a high level of total gene diversity in B. trilobata (H _T=0.308). A higher amount of polymorphism was found among than within populations. Genetic variation of populations from the primary forest (Tatras and Bia?owieza National Park) was higher than for those originating from disturbed habitats. The Bayesian method showed consistent grouping of samples corresponding with populations, with the best grouping in 12 different clusters reflecting a geographic pattern. The geographic pattern of genetic differentiation was supported by a neighbour-joining (NJ) dendrogram based on genetic distances. All mountain populations were grouped together in one subcluster, but lowland populations were more differentiated and did not form one clear group.     

Short-term impact of disturbance on genetic diversity and structure of Indonesian populations of the butterfly Drupadia theda in East Kalimantan

We investigated the short‐term impact of disturbance on genetic diversity and structure of the tropical butterfly Drupadia theda Felder (Lepidoptera: Lycaenidae). Populations were sampled from five landscapes in East Kalimantan (Borneo, Indonesia) which were differentially disturbed by selective logging and the 1997/1998 El Niño Southern Oscillation (ENSO)‐induced drought and fires. Sampling occurred before (in 1997) and after the forest fires (in 1998, 1999, 2000, and 2004). Drupadia theda populations underwent serious population size reductions following the 1997/1998 ENSO event. For a total of 208 individuals, we sequenced a 509‐bp segment of mtDNA containing the control region plus the 5’ end of the 12S rDNA gene. Haplotype diversity in D. theda populations ranged from 0.468 to 0.953. Just after the 1997/1998 ENSO event, number of recorded individuals and genetic diversity were very low in D. theda populations sampled in the two severely burned areas and in a small pristine forest fragment that was surrounded by burned forest and thereby affected by drought. Interestingly, higher levels of genetic diversity were observed in logged forest compared to proximate pristine forest. After 1998, the genetic composition within the three ENSO‐disturbed areas diverged. In the twice‐burned forest, the genetic diversity in 1999 already approached pre‐fire levels, while it remained nearly unchanged in proximate once‐burned forest. Our data suggest that the 1997/1998 ENSO‐induced drought and fires caused massive reductions in the genetic diversity of D. theda and that population recoveries were linked to their geographical position relative to patches of unburned forest (and thus to source populations).     

Epiphytes in human settlements in rural Panama

Background: An ever-increasing proportion of tropical ecosystems are affected by on-going land-use changes, stressing the importance of understanding how organisms cope with biotic and abiotic challenges outside their natural habitat. An important group in the tropics are vascular epiphytes, whose response to human disturbance is poorly understood.

Aims: Creating a baseline data set of epiphyte diversity in human settlements and assessing differences with assemblages of less disturbed habitats.

Methods: We surveyed the vascular epiphyte assemblages in 25 settlements of south-west Panama along a rainfall gradient. We tested how epiphyte assemblages were affected by human disturbance and climate by comparing our data to that of pastures and forest.

Results: Almost half (238 of 499) of all studied trees hosted at least one epiphyte. Altogether, 10,700 epiphytes of 56 species were found. Rainfall strongly affected both composition and diversity of epiphyte assemblages, whereas geographic proximity did not. In settlements, the species pool was considerably smaller than in pastures and undisturbed forest; however, settlements’ diversity was only significantly lower compared to pastures.

Conclusions: Epiphyte assemblages in settlements had a diminished species pool but diversity per tree was comparable to less disturbed habitats. Unsurprisingly, rainfall seems to be the main determinant of epiphyte diversity in rural settlements.     

Anthropogenic disturbances and plant biodiversity in forests of Uttaranchal,central Himalaya

Eight forest types varying in disturbance frequencies were identified along an elevational gradient in Uttaranchal, central Himalaya. Low elevation forests were close to human habitation and had high disturbance frequency, while high elevation forests were situated far from the human habitation and had low disturbance. The dominant tree species at low elevation were Pinus roxburghii and Quercus leucotrichophora, while Q. floribunda and Q. semecarpifolia dominated the high elevation forests. Pyracantha crenulata was the shrub present in all the forests except in Q. semecarpifolia forest and Anaphalis contorta, a herb species, was present in all the forests. Disturbance decreased the dominance of single species and increased the plant biodiversity by mixing species of different successional status. Species richness and diversity for all the vegetation layers were higher in low elevation–high disturbance forests. Mean tree density decreased from high to moderate and increased in low disturbance. The shrub density decreased from high to low disturbance while the reverse occured for herbs. High proportion of early successional species in disturbed forests indicated that disturbance induces succession. The mean number of young individuals increasing from high to low disturbance indicates that disturbance adversely affects regeneration. But, however, the high number of young individuals of Coriaria nepalensis, a small non-leguminous nitrogen fixing tree, in disturbed forests shows that the forest is regenerating. This species could be helpful in the re-establishment of original vegetation through triggering the regeneration of these forests. High elevation–low disturbed forests separated from low elevation–high disturbed forests. Forest type and elevation may have more influence on tree richness while shrub and herb richness may be more sensitive to disturbance and forest types.     

不同干扰生境下河口莲座蕨遗传多样性分析

该研究利用 ISSR 分子标记,对不同生境下的6个河口莲座蕨种群进行遗传多样性分析。结果表明：从44条ISSR引物中筛选出8条能够扩增出清晰、稳定条带的引物,对6个河口莲座蕨种群进行基因组 DNA扩增,共扩增出144条带,其中多态性条带119个,多态性条带比率为93.7％,Nei’s遗传多样性指数(H)为0.296,Shannon多样性指数(I)为0.457,遗传分化指数(Gst)为0.1520,种群遗传一致度和遗传距离分别为0.9138~0.9548和0.0584~0.0901;UPGMA聚类分析表明,种群间遗传距离与空间距离和生境类型有关。河口莲座蕨在不同干扰程度的生境中,种群具有高水平的遗传多样性,一定强度或频率的干扰生境中,种群遗传多样性较高,与海拔、坡度和坡向无相关性。     

Effects of population size and forest management on genetic diversity and structure of the tuberous orchid Orchis mascula

Due to societal changes and altered demands for firewood, the traditional forest management of coppicing has been largely abandoned. As a result, many forest herbs that are specifically adapted to regular opening of the canopy, have suffered significant declines in abundance, and the remaining populations of these species often tend to be small and isolated. Reduced population sizes and pronounced spatial isolation may cause loss of within-population genetic diversity and increased between-population differentiation through random genetic drift and inbreeding. In this study, we investigated genetic diversity and genetic structure of 15 populations of the food-deceptive orchid Orchis mascula using AFLP markers. Within-population genetic diversity significantly increased with increasing population size, indicating genetic impoverishment in small populations. Genetic differentiation, on the other hand, was rather low (Φ_ST = 0.083) and there was no significant relationship between genetic and geographic distances, suggesting substantial gene flow within the study area. However, strong differences in levels of within-population diversity and among-population differentiation were found for populations located in forests that have been regularly coppiced and populations found in forests that were neglected for more than 50 years and that were totally overgrown by shrubs. Our data thus indicate that a lack of coppicing leads to decreased genetic diversity and increased differentiation in this orchid species, most likely as a result of genetic drift following demographic bottlenecks. From a conservation point of view, this study combined with previous results on the demography of O. mascula in relation to forest management illustrates the importance of coppicing in maintaining viable populations of forest herbs in the long-term.     

Is genetic structure of the southern pygmy mouse Baiomys musculus (Cricetidae) related to human-induced spatial landscape heterogeneity in a tropical dry forest?

Tropical dry forests are biologically important biomes sustaining a high rate of endemic species. However, these forests are highly threatened by human activities that negatively impact them on distinct levels, including the genetic diversity. Within the framework of landscape genetics (that seeks to evaluate the relation of characteristics of the environmental matrix with population genetics), we used ISSR markers to evaluate the relationship between the alteration of tropical dry forest by human-induced activities (conserved vs. disturbed) with the genetic structure of four breeding sites of the southern pygmy mouse Baiomys musculus. Averaging among the 105 loci used, the unbiased heterozygosis per population (0.247–0.305) was statistically similar among the four sites, as well as between conserved and disturbed conditions (2-way ANOVA F _(3,16)?=?1.47, P?=?0.1984). The genetic differentiation among the four breeding sites was high (F _ST?=?0.1122; 95?% CI 0.082–0.146) considering the geographical scale evaluated (ca. 4?km). Both, a factorial correspondence analysis and a model-based clustering analysis showed the existence of four genetic groups (one per breeding site). However, no association of genetic structure with disturbance conditions was revealed by these analyses. The absence of differences in mean genetic diversity and the lack of association of genetic structure with habitat transformation suggest that B. musculus has enough behavioral plasticity and enough genetic diversity to respond to environmental heterogeneity caused by human activities. We discussed conditions in which habitat transformation could indeed favor B. musculus.     

Maintaining diversity through intermediate disturbances: evidence from rodents colonizing rehabilitating coastal dunes

Rodents inhabit the coastal dune forests of KwaZulu‐Natal, South Africa. Here habitat rehabilitation following mining of dunes has resulted in coastal dune forest succession similar to that recorded in nonmined forests. We investigated the colonization of rehabilitating stands and evaluate the role of disturbance in maintaining rodent diversity. A trapping programme was established between July 1993 and February 1995 during which rodent colonization, local extinction and species richness were recorded for rehabilitating stands of different ages. Trends in these variables were closely associated with one of three possible outcomes for a disturbed patch over time, with no intervening disturbances following the initial disturbance. Colonization was initially high which led to an increase in species richness. Extinction was lower than colonization, but became higher when the habitat was 3 years old, which led to a decline in richness. We extrapolate this result assuming negligibly small disturbances after the initiation of rehabilitation and suggest that intermediate levels of disturbance maintain rodent species richness in coastal dune forests. Furthermore, our results illustrated species turnover, a prediction of the recorded outcome, with young stands dominated by Mastomys natalensis and older stands by Saccostomus campestris or Aethomys chrysophilus.     

Patterns of Genetic Variation in Swertia przewalskii, an Endangered Endemic Species of the Qinghai-Tibet Plateau

Swertia przewalskii Pissjauk. (Gentianaceae) is a critically endangered and endemic plant of the Qinghai-Tibet Plateau in China. RAPD and ISSR analyses were carried out on a total of 63 individuals to assess the extent of genetic variation in the remaining three populations. Percentage of polymorphic bands was 94% (156 bands) for RAPD and 96% (222 bands) for ISSR. A pairwise distance measure calculated from the RAPD and ISSR data was used as input for analysis of molecular variance (AMOVA). AMOVA indicated that a high proportion of the total genetic variation (52% for RAPD and 56% for ISSR) was found among populations; pairwise Φ _ST comparisons showed that the three populations examined were significantly different (p < 0.001). Significant genetic differentiation was found based on different measures (AMOVA and Hickory θ_B) in S. przewalskii (0.52 on RAPD and 0.56 on ISSR; 0.46 on RAPD and 0.45 on ISSR). The differentiation of the populations corresponded to low average gene flow (0.28 based on RAPD and 0.31 based on ISSR), whereas genetic distance-based clustering and coalescent-based assignment analyses revealed significant genetic isolation among populations. Our results indicate that genetic diversity is independent of population size. We conclude that although sexual reproduction and gene flow between populations of S. przewalskii are very limited, they have preserved high levels of genetic diversity. The main factors responsible for the high level of difference among populations are the isolation and recent fragmentation under human disturbance.     

Diversity and abundance of vascular epiphytes: a comparison of secondary vegetation and primary montane rain forest in the Venezuelan Andes

Species diversity of vascular epiphyte plant communities was studied in La Carbonera, a montane rain forest dominated by Podocarpaceae in the Venezuelan Andes. We compared the epiphyte communities of the primary, disturbed, and secondary forest areas of La Carbonera in order to augment the scarce knowledge on the effects of anthropogenic disturbance on these important elements of tropical vegetation. Diversity of vascular epiphytes (191 species in the whole forest area) was low in the disturbed and secondary areas (81 spp.) compared to adjacent primary forest (178 spp.). Four types of disturbed forest and secondary vegetation supported different numbers of epiphyte species, showing a decline with increasing degrees of disturbance (65 spp. along a road transect, 42 spp. on relict trees in disturbed forest, 13 spp. in a tree plantation and 7 spp. in a former clearing, both secondary vegetation units). Epiphytic species composition in primary and disturbed or secondary forest areas differed markedly: disturbed habitats harboured fewer fern and orchid species but more bromeliad species than the primary forest. Probably the families occurring only in primary forest sites of our study may be useful as bioindicators to determine the degree of disturbance in other habitats of mountain rain forests as well. Epiphyte abundance was also lower in disturbed habitats: a remnant emergent tree supported only about half as many epiphyte individuals as a member of the same species of similar size in the primary forest. The decrease in species numbers and abundance as well as the differences in species composition are mainly due to the less diverse phorophyte structure and less differentiated microclimate in the disturbed and secondary vegetation compared to the primary forest.     

Pollen flow in fragmented landscapes maintains genetic diversity following stand-replacing disturbance in a neotropical pioneer tree,Vochysia ferruginea Mart

In forests with gap disturbance regimes, pioneer tree regeneration is typically abundant following stand-replacing disturbances, whether natural or anthropogenic. Differences in pioneer tree density linked to disturbance regime can influence pollinator behaviour and impact on mating patterns and genetic diversity of pioneer populations. Such mating pattern shifts can manifest as higher selfing rates and lower pollen diversity in old growth forest populations. In secondary forest, where more closely related pollen donors occur, an increase in biparental inbreeding is a potential problem. Here, we investigate the consequences of secondary forest colonisation on the mating patterns and genetic diversity of open-pollinated progeny arrays for the long-lived, self-compatible pioneer tree, Vochysia ferruginea, at two Costa Rican sites. Five microsatellite loci were screened across adult and seed cohorts from old growth forest with lower density, secondary forest with higher density, and isolated individual trees in pasture. Progeny from both old growth and secondary forest contexts were predominantly outcrossed (t_m=1.00) and experienced low levels of biparental inbreeding (t_m−t_s=0.00–0.04). In contrast to predictions, our results indicated that the mating patterns of V. ferruginea are relatively robust to density differences between old growth and secondary forest stands. In addition, we observed that pollen-mediated gene flow possibly maintained the genetic diversity of open-pollinated progeny arrays in stands of secondary forest adults. As part of a natural resource management strategy, we suggest that primary forest remnants should be prioritised for conservation to promote restoration of genetic diversity during forest regeneration.     

Population biology of two land snails (Mesomphix spp.): variation among six southern appalachian sites with differing disturbance histories

Summary Ecological and genetic properties of two North American terrestrial gastropods (Mesomphix spp.) were characterized in paired control and previously logged watersheds in two North Carolina forests (Coweeta and the Great Smoky Mountains National Park) of the Southern Appalachian Biosphere Reserve Cluster. Shell growth was greater in the control sites, but density and mortality were largely independent of prior logging history and forest reserve. Based on starch gel electrophoresis data, both species showed their highest levels of genetic diversity in the Coweeta forest, the component of the reserve cluster which had the most extensive and variable history of logging disturbance. M. subplanus also exhibited higher levels of heterozygosity in logged than in control watersheds, and M. andrewsae showed over twice as many rare alleles in disturbed sites as in control sites. F-statistic analysis depicted both excess levels of homozygosity and moderate genetic differentiation among the populations, reflecting the effects of small population size and perhaps drift and inbreeding. Estimated gene flow was relatively low. These results correspond to the recent finding by Bryant et al. (1987) and others on the effects of bottlenecks, and to the contrasting history of habitat instability of the two major study forests.     

Disturbances by human trampling alter the performance,sexual reproduction and genetic diversity in a clonal woodland herb

Disturbances play a major role in structuring the community composition in a variety of ecosystems. The potential impact of disturbances on sexual reproduction and genetic diversity of plants has so far received little attention. We examined the effects of disturbance by human trampling on the performance, sexual reproduction and clonal diversity in the woodland herb Anemone nemorosa in six sites disturbed by intensive recreational activities and in six undisturbed sites in suburban forests in Switzerland. Disturbance by human trampling decreased shoot height of A. nemorosa and altered the size-dependent flowering probability function. Furthermore, in disturbed sites an increased percentage of aborted seeds was found, resulting in a reduced sexual reproductive potential of A. nemorosa populations. Both clonal and genetic diversity of A. nemorosa were reduced in disturbed sites. Our study shows for the first time that disturbance by human trampling can decrease the genetic diversity in a clonal woodland plant. This suggests that genetic aspects of woodland plants should be considered in restoring degenerated forest sites.     

Conservation genetics of two island endemic Ribes spp. (Grossulariaceae) of Sardinia: survival or extinction?

Measuring levels of population genetic diversity is an important step for assessing the conservation status of rare or endangered plant species and implementing appropriate conservation strategies. Populations of Ribes multiflorum subsp. sandalioticum and R. sardoum, two endangered endemic species from Sardinia, representing the whole genus on the island, were investigated using ISSR and SSR markers to determine levels and structure of genetic variability in their natural populations. Results indicated medium to low genetic diversity at the population level: Nei's gene diversity for ISSR markers ranged from 0.0840 to 0.1316; the expected heterozygosity (H_E) for SSR ranged from 0.4281 to 0.7012. In addition, only one remnant population of R. sardoum showed a high level of inbreeding, in accordance with its very small size. Regarding the structure of the six R. sandalioticum populations, both principal coordinates analysis (PCoA) and STRUCTURE analysis of ISSR and SSR data highlighted low population structure, although two populations appeared to be clearly distinct from the others. The genetic pattern of the two taxa associated with their different ecological positions indicated resilience of R. sandalioticum populations in fresh and humid habitats and uncertain future resistance for the residual R. sardoum population in xeric calcareous stands. Hence, this study highlights the importance of an integrated conservation approach (genetic plus in situ and ex situ conservation studies/measures) for activating management programmes in these endemic and threatened taxa that can be considered as crop wild relatives of cultivated Ribes species.