Unexpected high levels of genetic variability and the population structure of an island endemic rodent (Oryzomys couesi cozumelae)

Oryzomys couesi cozumelae is an endemic, threatened rodent from Cozumel Island, Mexico. We estimated its genetic diversity and structure by analyzing microsatellite loci in 228 samples from 12 sampling sites widely distributed throughout the island. Unexpected high levels of genetic and allelic diversity were found: a total of 54 alleles, an average of 10.8 alleles per locus, and high heterozygosity values (mean H_O = 0.624, H_E = 0.690 and H_Nei = 0.689). These values are higher than those reported for small sized insular mammals, higher than that found in 37 individuals of the mainland O. couesi from southern Mexico (H_O = 0.578) that we analyzed for comparative purposes, and similar to those of other mainland small mammal populations. Despite factors that affect Cozumel’s biota, such as exotic predators and competitors, hurricanes, seasonal population fluctuations and anthropogenic activities, no evidence of genetic bottlenecks was found. A significant population structure was observed and a model of isolation-by-distance was supported. Our findings render O. c. cozumelae a high conservation value, not only for its high genetic diversity and structure, but because available data suggests that its population has declined significantly in recent years. Further habitat fragmentation and population isolation could result in a higher genetic structure and loss of genetic diversity. The protection of habitat, the maintenance of habitat connectivity and the removal of introduced competitors and predators are a conservation priority. Acknowledging that the genetic structure of populations has crucial conservation implications, the present genetic information should be taken into account in management plans for the conservation of O. c. cozumelae.     

Relationship between reservoir size and genetic differentiation of the stream caddisfly Stenopsyche marmorata

Reservoirs have the potential to block the gene flow of stream macroinvertebrates along a channel, which takes place via larval drift and adult flight, resulting in genetic differentiation above and below the reservoirs. Gene flow across the reservoirs may be strongly obstructed if the area of standing water is larger. Using random amplified polymorphic DNA markers, we investigated the genetic structure of Stenopsyche marmorata (Stenopsychidae: Trichoptera) populations found above and below the reservoirs, and the reference stream of six reservoirs with small to large water surface area ranging from 0.12 km² to 6.00 km². As a result, the two largest reservoirs with a standing water area larger than 3.27 km² showed significant differences in pairwise θ between fragmented and reference streams, whereas the other four reservoirs with a standing water area smaller than 1.64 km² showed insignificant differences. The genetic differentiations in the two largest reservoirs did not result in the reduction of genetic diversities in the fragments. Based on the significant correlation between relative population size and mean expected heterozygosity, we concluded that local genetic diversities were constrained in smaller populations due to the effect of genetic drift.     

Spatial demographic and genetic consequences of harvesting within populations of the terrestrial orchid Cymbidium goeringii

Populations of many orchids, especially terrestrial species, have been rapidly decreasing due to mass collection by plant sellers and enthusiasts. Given the presumably negative demographic and genetic consequences, such anthropogenic activity should be taken into consideration for predicting ecological and evolutionary dynamics and for planning conservation strategies. To determine how recent human disturbance alters spatial demographic and population genetic processes, populations of the terrestrial orchid Cymbidium goeringii located in South Korea were examined to quantify the spatial distributions of individuals and genotypes with respect to three levels of disturbance: “disturbed” (four populations), “putatively disturbed” (two), and “undisturbed” (two). Undisturbed and putatively disturbed populations were found to possess significantly positive spatial clustering of individuals over a range of spatial scales. In contrast, disturbed populations exhibited little or no spatial aggregation, consistent with the selective removal of plants by collectors from higher density areas within these populations. Although overall genetic differentiation among populations was moderate and significant (F_ST = 0.082), levels of genetic diversity within populations were similar despite the different disturbance histories (mean H_e = 0.257-0.324). Spatial genetic autocorrelation analyses revealed that the undisturbed populations exhibited significant declines in kinship (F_ij) with distance, that mean kinship at interplant distances of ?4-6 m was significantly greater than zero and between plants ?0.5 m apart was in the range expected for first cousins to half-sibs. In contrast, only one putatively disturbed and one disturbed population exhibited significant declines in kinship with distance. These differences between disturbed versus putatively disturbed and undisturbed populations in the spatial distribution of individuals and genetic variation likely reflect the consequences of mass collections. Since these differences (and reduced population density) have important implications for future ecological and evolutionary trajectories, conservation managers of endangered terrestrial orchids may want to analyze the spatial distribution of individuals and their genotypes to infer whether a population with few individuals represents a natural state or the likely outcome of mass collection.     

Genetic diversity of core and peripheral Sitka spruce (Picea sitchensis (Bong.) Carr) populations: implications for conservation of widespread species

This study investigated levels of genetic diversity and population differentiation among Sitka spruce (Picea sitchensis) populations classified as core or peripheral based on ecological niche, and continuous or disjunct based on species distribution. Large numbers of trees (N = 200) were sampled from each of eight populations to evaluate the distribution of rare as well as common alleles across the species range. Codominant alleles for eight sequence-tagged site loci were classified based on frequency and geographic distribution in order to develop appropriate sampling strategies to target specific classes of alleles. An important finding of this study is the similarity in genetic diversity as measured by expected heterozygosity between core populations (mean H_E = 0.58) and peripheral populations (mean H_E = 0.56). However, there was significant inbreeding in peripheral (F_IS = 0.17) but not in core (F_IS = 0.03) populations. Large differences in gene flow estimates were observed between core (Nm = 9.0) and peripheral populations (Nm = 3.5). Irrespective of population classification, over 75% of the alleles were common and widespread. Only one allele was classified as rare and localized, and this allele was limited to one core, disjunct and two peripheral, disjunct populations. There was stronger evidence of past bottlenecks in peripheral, disjunct populations than in core, continuous populations. Results are used to suggest sampling strategies for capture of maximum level of genetic diversity and conservation of rare alleles. The conservation of peripheral, particularly disjunct, populations as well as populations in putative glacial refugia may present the best opportunity for conserving rare alleles.     

Dispersal of the endangered flightless beetle Dorcadion fuliginator (Coleoptera: Cerambycidae) in spatially realistic landscapes

Habitat destruction and degradation are the major causes for the decline of the endangered grass-feeding beetle Dorcadion fuliginator in Central Europe. In the southern part of the Upper Rhine valley (border region of Switzerland, Germany and France) the habitat suitable for this flightless beetle has been reduced to small remnants of extensively managed dry grassland, usually surrounded by intensively cultivated agricultural fields or settlements. Using a mark-release-resight technique we examined movement patterns in three D. fuliginator populations to obtain basic information on the dispersal ability and longevity of this beetle. Estimated daily survival rates ranged from 88.8% to 90.8% in the populations examined. This corresponds to a mean life span of 10.5 days. Distances moved by D. fuliginator differed among populations. The beetles walked the largest distances in the verges of a field track. Several beetles moved distances of 20-100 m along the track, with a maximum distance of 218 m (a male in 12 days). The shortest displacements were recorded in the bank of the river Rhine, a narrow habitat surrounded by tarmac roads. We also assessed the spatial arrangement of 12 patches with D. fuliginator populations in two regions and estimated the size of each population over 4 years. Data on dispersal, daily survival, population size and spatial arrangement of patches were used to simulate patch-specific migration rates. The simulations suggested that in both areas the beetles regularly moved between neighbouring patches separated by distances shorter than 100 m, whereas patches separated by distances exceeding 500 m are isolated.     

ISSR analysis shows low genetic diversity versus high genetic differentiation for giant bamboo, Dendrocalamus giganteus (Poaceae: Bambusoideae), in China populations

Dendrocalamus giganteus Munro is a high-value woody bamboo widely grown in Southeast Asia and China’s Yunnan Province. We investigated its genetic diversity in Yunnan as a prelude to considering effective breeding programs and the protection of germplasm resources. Inter-simple sequence repeat (ISSR) markers were used to assess the genetic structure and differentiation of seven populations. Seven ISSR primers generated 140 bands, of which 124 were polymorphic (88.57%). Genetic diversity within populations was relatively low, averaging 11.33% polymorphic bands (PPB), while diversity was considerably higher among populations, with PPB = 88.57%. Greater genetic differentiation was detected among populations (G _ST = 0.8474). We grouped these seven populations into two clusters within an UPGMA dendrogram—one comprised the Xinping and Shiping populations from central Yunnan, the other included the remaining five populations. Mantel tests indicated no significant correlation between genetic and geographic distances among populations. Breeding system characteristics, genetic drift, and limited gene flow (N _m = 0.0901) might be important factors for explaining this differentiation. Based on the overall high genetic diversity and differentiation among D. giganteus populations in Yunnan, we suggest the implementation of in situ conservation measures for all populations and sufficient sampling for ex situ conservation collections.     

Low impact of present and historical landscape configuration on the genetics of fragmented Anthyllis vulneraria populations

Decreasing habitat fragment area and increasing isolation may cause loss of plant population genetic diversity and increased genetic differentiation between populations. We studied the relation between the historical and the present landscape configuration (i.e., patch area and patch connectivity), and the present management of calcareous grassland fragments on the one hand, and the within and between population genetic structure of 18 Anthyllis vulneraria populations on the other hand. Despite the long-time fragmentation history and the mainly selfing breeding system of the species, we detected very low genetic differentiation (Φ_st = 0.056) among habitat fragments and no significant isolation-by-distance relation. Average within fragment genetic diversity measured as molecular variance and expected heterozygosity, were relatively high (16.46 and 0.28, respectively), and weakly positively correlated with the current fragment area, most likely because larger fragments contained larger populations. We found no effects of the historical landscape configuration on the genetic diversity of the populations. Our data suggest that the consequences of habitat fragmentation for genetic differentiation and genetic diversity of A. vulneraria are relatively minor which is very likely due to the historical high levels of seed exchange among fragments through grazing and roaming livestock. This study provides indirect evidence that nature management by grazing not only positively affects habitat quality but that it might also mitigate the genetic consequences of habitat fragmentation. From the conservation point of view, this study illustrates the importance of grazing and of the regular transport of livestock between fragments to prevent the long-term effects of fragmentation on the genetic diversity of the populations studied.     

Reduced seed production, inbreeding, and pollen shortage in a small population of a threatened tree, Magnolia stellata

We investigated how genetic factors and pollen shortage affect seed production in a small population of Magnolia stellata, a threatened insect-pollinated tree. We used microsatellite and manual pollination techniques, and compared a small population to a large one. Compared to the large population, the small population showed low allelic variation and had an F_IS significantly greater than 0 in adults, indicating that genetic deterioration, including genetic drift and inbreeding, may have occurred in adults. Manual self-pollination lowered seed production relative to manual cross-pollination to a different extent between populations: δ (the magnitude of inbreeding depression due to self-fertilization) was lower in the small population than in the large population. However, under natural pollination, the estimated embryo mortality rates after ovules self-fertilized were similar between the two populations because the primary selfing rate was higher in the small population. The ovule mortality rate due to pollen shortage and that due to factors independent of pollen shortage and selfing were both approximately 10% higher in the small population, suggesting that pollen transfer may have decreased and genetic deterioration effects may have increased in that population. These factors reduced seed production in the small population (female reproductive success = 0.3%) compared to the large population (2.6%). Our results suggest that seed production in the small population of M. stellata is strictly limited by elevated pollen shortage, selfing, and genetic deterioration in adults, which accelerate the risk of extinction.     

Genetic diversity and differentiation in Chinese sour cherry <Emphasis Type="Italic">Prunus pseudocerasus</Emphasis> Lindl., and its implications for conservation

In this study, the genetic diversity and differentiation of 10 natural Prunus pseudocerasus Lindl. populations were investigated using inter-simple sequence repeat (ISSR) markers. Totally, 18 selected primers generated 150 loci, with an average of 8.33 bands per primer. The results showed that the percentage of polymorphic bands (PPB) was pretty low at the population level (PPB = 1.13–32%), but relatively high at the species level (PPB = 84%). Besides, a high level of genetic differentiation among populations was detected based on the gene differentiation coefficient (G _ST = 0.7118) and the hierarchical analysis of molecular variance (AMOVA) (Φ _ST = 64.53%, P < 0.001), in line with the low inter-population gene flow (N _m = 0.2025). Moreover, Mantel test revealed a significant correlation between genetic and geographic distances among the populations (r = 0.5272, P < 0.005). The high level of intraspecific genetic diversity was probably related with its life history traits, while its small population size and the resultant high levels of genetic drift and inbreeding might explain the low genetic diversity within populations. The relatively high inter-population genetic differentiation was largely attributed to its small population size, habitat fragmentation, the mode of pollen and seed dispersal, and geographic isolation. Based on the present study, conservation strategies were proposed to preserve this valuable natural germplasm resource.     

Ex situ genetic conservation of endangered Vatica guangxiensis (Dipterocarpaceae) in China

RAPD polymorphisms were applied to check the efficiency of ex situ genetic conservation of endangered Vatica guangxiensis X. L. Mo. endemic to southwestern China. Low level of genetic variation was revealed in three remaining natural populations. Twenty random primers, each with 10 base pairs, generated 231 bands with 53.68% being polymorphic, and with an average of 32.46% being polymorphic in each natural population. Strong population differentiation was revealed by AMOVA (analysis of molecular variance) and Gst value was 0.3764. The population ML ex situ conserved in the Xishuangbanna Tropical Botanical Garden contained an intermediate genetic variation compared with natural populations, with 30.74% bands being polymorphic. Of the total 231 bands generated in V. guangxiensis, 204 bands were also detected in population ML, indicating that 88.31% of the total genetic variations of this species were conserved in ex situ population. If only the alleles with moderate to high frequency (P>0.05) were considered, 204 out of 209 bands (97.61%) occurred in ex situ population ML. RAPD analysis also detected one exclusive band in natural population NS, and five in natural population NP, three of these exclusive bands were generated in every samples of natural population (NP), and other three had moderate to high frequencies. While none of these exclusive bands were detected in ex situ conserved population ML. Our conclusions are that the ex situ conserved population ML contains representative genetic variation to maintain long-term survival and evolutionary process of V. guangxiensis, and that more extensive ex situ sampling in natural population NS and NP is needed to conserve more exclusive alleles in ex situ population. The tropical area in the Botanical Garden would play a more important role in the ex situ conservation of rare and endangered plants.     

Are populations of the candy barrel cactus (Echinocactus platyacanthus) in the desert of Tehuacán, Mexico at risk? Population projection matrix and life table response analysis

Echinocactus platyacanthus is a candy barrel cactus endemic to Mexico and an endangered species owing to its exploitation and the destruction of its habitat. The population dynamic of this species is analyzed using matrix models. Three consecutive censuses were carried out (1997, 1998, and 1999) for six populations of this species in the Tehuacán-Cuicatlán Biosphere Reserve. Fruit contain many seeds (mean = 171 ± S.E. 11.03 seeds/fruit); seedling establishment and survival are low (2 × 10⁻⁶), and fecundity increases as the diameter of the individuals increases (62 seeds in adult 1-4322 in adult 4). The rates of population growth (λ) range from 0.9285 to 1.0005. Elasticity values for demographic processes indicate that the stasis of the adults is the greatest contribution (S = 0.982), followed by growth (G = 0.017) and fecundity (F = 0.001) to λ. The populations are located in the lower left corner of the demographic triangle; however, there are variations for a given population from one year to the next. Life table response experiments indicate that although there are local variations, the most important differences in the values of λ between populations and between years are associated with changes in the stasis of the adults. The disturbance index is not directly related to population density or to the current value of λ. The protection of adult E. platyacanthus must be taken into account for the management of this species and its conservation in the study area.     

Genetic diversity and local population structure of fragmented populations of Trillium camschatcense (Trilliaceae)

Trillium camschatcense, a long-lived common woodland herb, has been experiencing intensive habitat fragmentation over the last century in eastern Hokkaido, Japan. We examined the genetic diversity and population genetic structure of 12 fragmented populations with different population sizes using allozyme electrophoresis. The percentage of polymorphic loci and mean number of alleles per locus were positively related to population size, probably due to the stochastic loss of rare alleles (frequency of q<0.1) in small populations. Populations with 350 flowering plants or fewer had lost almost all of their rare alleles. While the heterozygosity and inbreeding coefficient were not related to population size, some small populations showed relatively high inbreeding coefficients. In spite of the low genetic differentiation among overall populations (F_ST=0.130), local population structuring was recognized between the two geographically discontinuous population groups. Within groups, sufficient historical gene flow was inferred, whereas a low dispersal ability of this species and geographical separation could produce apparent differentiation between groups.     

Dynamics of a black bear population within a desert metapopulation

Understanding metapopulation dynamics in large carnivores with naturally fragmented populations is difficult because of the large temporal and spatial context of such dynamics. We coupled a long-term database of visitor sighting records with an intensive 3-year telemetry study to describe population dynamics of recolonization by black bears (Ursus americanus) of Big Bend National Park in Texas during 1988-2002. This population, which occurs within a metapopulation in western Texas and northern Mexico, increased from a single pair of known breeding-age animals in 1988 to 29 bears (including 6 females of breeding age) in March 2000 (λ = 1.25/year). A migration and dispersal event in August-December 2000 reduced the population to 2 adult females and as few as 5-7 individuals. One-way movement distances from the study area during this event averaged 76 km for females (n = 7) and 92 km for males (n = 4), and 3 animals conducted migrations of at least 154, 178, and 214 km, respectively. Our observations exemplify the importance of stochastic events on demographics of small populations and highlight the potential scale of bear movement among montane islands of southwestern North America. They also provide insight into the use of dispersal data in parameterizing metapopulation models for large carnivores.     

Genetic structure, population dynamics, and conservation of Black caiman (Melanosuchus niger)

Microsatellite DNA polymorphisms were screened in seven populations of the largest Neotropical predator, the Black caiman Melanosuchus niger (n = 169), originating from Brazil, French Guiana and Ecuador. Eight loci were used, for a total of 62 alleles. The Ecuadorian population had the lowest number of alleles, heterozygosity and gene diversity; populations of the Guianas region exhibited intermediate diversities; highest values were recorded in the two populations of the Amazon and Rio Negro. During the last century Melanosuchus populations have been reduced to 1-10% of their initial levels because of hunting pressure, but no strong loss of genetic diversity was observed. Both the inter-locus g-test and the Pk distribution suggested no recent important recovery and/or expansion of current populations. On a global scale, the inter-population variation of alleles indicated strong differentiation (F_ST = 0.137).Populations were significantly isolated from each other, with rather limited gene flow; however, these gene flow levels are sufficiently high for recolonization processes to effectively act at regional scales. In French Guiana, genetic structuring is observed between populations of two geographically close but ecologically distinct habitats, an estuary and a swamp. Similar divergence is observed in Brazil between geographically proximate “black water” and “white water” populations. As a consequence, the conservation strategy of the Black caiman should include adequate ecosystem management, with strong attention to preservation of habitat integrity. Distribution of genetic diversity suggests that current populations originated from the central Amazonian region. Dispersal of the species may thus have been deeply influenced by major climatic changes during the Holocene/Pleistocene period, when the Amazonian hydrographic networks were altered. Major ecological changes such as glaciations, marine transgressions and a hypothesized presence of an Amazonian Lake could have resulted in extension of Black caiman habitats followed by isolation.     

Reproductive constraints for the long-term persistence of fragmented Acacia dealbata (Mimosaceae) populations in southeast Australia

Fragmented and degraded vegetation characterises agricultural landscapes across southern Australian. Remnant vegetation within these regions performs a number of vital ecological and hydrological roles, but little is known about whether or how fragmentation is affecting the long-term persistence of these critical landscape elements. Acacias are a significant component of many remnant vegetation communities across Australia, forming numerous integral faunal and floral relationships. Here, reproductive output of 11 fragmented Acacia dealbata (Mimosaceae) populations from across the southern tablelands of New South Wales was assessed over 2 years to identify reproductive constraints associated with increasing vegetation fragmentation. Fertilization success is the major reproductive constraint, particularly in small populations, and probably reflects a self-incompatible reproductive strategy. During 2002 larger and more dense populations produced more legumes (p = 0.014 and <0.001, respectively) while in 2003 these two variables were associated with increased fertilization success (p = 0.004 and 0.017, respectively). There was also some suggestion that populations with fewer exotic species also experienced increased fertilization success (p = 0.055). Assessment of plant performance within populations suggests that consistent reproductive output of particular individuals within small populations may limit reproductive compatibility within these populations over time. The long-term persistence of many small A. dealbata populations may be jeopardised by low seed set, and limited recruitment and aging stands. Immediate steps are now required to ensure that these populations continue contributing to landscape function by augmenting populations, improving connectivity, and allowing disturbance events that will stimulate recruitment.     

Cattle depredation by puma (Puma concolor) and jaguar (Panthera onca) in central-western Brazil

In this study, data on cattle depredation by puma (Puma concolor) and jaguar (Panthera onca) were recorded for six years (1998-2003) in a cattle ranch in central-western Brazil. Depredation represented 18.9% of the overall cattle mortality, being predominant on calves. In biomass, kills represented 0.4% (63.8 kg/km²) of the ranch’s annual stock. In economic loss, kills represented 0.3% of the cattle stock value. Depredation was mainly associated with cattle’s age class and location along with the time of birth of calves. The proportion of pastures next to forest with depredation (n = 33, 48.5%) was not distinguished to the proportion of pastures not bordering forest with depredation (n = 35, 51.5%). However, the proportion of pastures next to forest with depredation represented 54% (n = 33) of the 61 total pastures that were at least partially surrounded by forest patches or riparian forests that comprised eight continuum blocks of forest fragments of different sizes in the ranch and adjacent areas. No kills occurred in the central portion (main house) of the farm, close to the headquarters where the pastures not bordering forest. The distances of the kills in relation to areas of native forest was 1317.48 ± 941.03 m. In order to reduce depredation, calves should be kept as far as possible from forest areas and concentrated cattle breeding and calving seasons should be encouraged.     

Successful reintroductions of the endangered long-lived Sargent’s cherry palm, Pseudophoenix sargentii, in the Florida Keys

The 1991-1994 reintroductions of Florida endangered Pseudophoenix sargentii to 13 Florida Keys sites represent a rare example of a successful multi-agency long-term effort to conserve a long-lived palm. To assess reintroduction success, we compared population demographics with and without reintroduced plants and conducted population viability analyses. Since 1991, the wild population has increased 6.4-fold. Survival from 2000-2004 was 94%, growth was positive (λ = 1.013), and there was no predicted extinction risk. Recent wild population growth is attributed to good seedling recruitment and removing the greatest threats. After 14 years, reintroductions had 43% survival, increased total plants in the wild by 27%, and expanded the species’ distribution. Reintroduced plants had faster maturation rates, improved population age structure, and enhanced population growth (λ = 1.032). Success varied with transplant year, location, microsite, and original transplant size. Failures in 1991 and at some historic sites emphasize the need for a multi-year, multi-site approach to reintroductions to buffer against stochastic losses. Rockland hammocks and the tops of coastal berms had greatest plant growth and survival. Large transplants had the greatest survival. Because no reintroduced plants are reproductive, transitions between stages are extremely slow, and plants may require >30 years to mature, continued institutional dedication to long-term monitoring will be required to assess whether the populations are self-sustaining. Horticultural expertise and ex situ collections complimented support of land managing agencies for the species’ preservation. These first rare plant reintroductions to Florida State Parks opened avenues for more plant conservation efforts and public interpretation.     

AFLP fingerprinting of Anchusa (Boraginaceae) in the Corso-Sardinian system: Genetic diversity, population differentiation and conservation priorities in an insular endemic group threatened with extinction

Although several plants endemic to Corsica and Sardinia are included in various redlists, no attempts have been made to analyse their genetic diversity with molecular techniques. Genus Anchusa occurs with seven taxa in either mountain or coastal habitats of the two islands, but the very restricted range and low population size pose these endemisms in a very precarious conservation status. Highly variable markers (AFLP) were therefore used to analyse the patterns and levels of genetic diversity in a sample of 11 populations from the entire range of the group.Results indicate the separation between a mountain genic pool including Anchusa formosa, Anchusa capellii and Anchusa montelinasana, and four groups of coastal accessions. In spite of small size, mountain taxa show low interpopulation differentiation (F_st = 0.02) and relatively high intrapopulation genetic variation (0.365), while coastal accessions showed on average a stronger differentiation (mean F_st = 0.20) and a lower diversity (0.281), possibly due to higher rates of inbreeding. The particularly low levels of variation found in A. sardoa, A. littorea and A. crispa ssp. maritima from the Coghinas bay are likely due to a historical decrease of populations and to bottleneck events caused by loss of habitat and natural stochastic factors on sand dune ecosystems. While habitat maintenance and regulation of grazing by domestic herbivores should be sufficient to ensure the persistence of the mountain endemics, additional actions of in situ and ex situ conservation are needed for the critically endangered coastal species A. sardoa and A. littorea. A. crispa showed a relatively high variation, especially on Corsica. No correlation between population size and genetic variation was found in the latter species, highlighting the importance of the small patches for its conservation. Also, the genetic separation between subspecies crispa and maritima stresses the need of keeping them distinct in redlists and conservation actions on Sardinia.     

Estimating the dispersal capacity of the rare lichen Cliostomum corrugatum

The objective of this study was to estimate the dispersal rate in an organism assumed to be confined to tree stands with unbroken continuity. We used the lichen-forming ascomycete Cliostomum corrugatum, which is largely confined to old oak stands. Five populations, with pairwise distances ranging from 6.5 to 83 km, were sampled in Östergötland, south-eastern Sweden. DNA sequence data from an intron in the small subunit nuclear ribosomal RNA gene was obtained from 85 samples. Nearly all molecular variance (99.6%) was found within populations and there were no signs of isolation-by-distance. The absolute number of immigrants per population per generation (estimated to 30 years), inferred by Bayesian MCMC, was found to be between 1 and 5. Altogether, evidence suggests abundant gene flow in the history of our sample. A simulation procedure demonstrated that we cannot know whether effective dispersal is ongoing or if it ceased at the time when oaks started to decrease dramatically around 400 years BP. However, a scenario where effective dispersal ceased already at the time when the postglacial reinvasion of oak had reached the region around 6000 years BP is unlikely. Vegetation history suggests that the habitat of C. corrugatum was patchily distributed in the landscape since the early Holocene. Combined with the high dispersal rate estimate, this suggests that the species has been successful at frequently crossing distances of at least several kilometres and possibly that it has primarily been limited by the availability of habitat rather than by dispersal.     

Field characterization of olive (Olea europaea L.) tree crown architecture using terrestrial laser scanning data

Since the introduction of Terrestrial Laser Scanning (TLS) instruments, there now exists a means of rapidly digitizing intricate structural details of vegetation canopies using Light Detection and Ranging (LiDAR) technology. In this investigation, Intelligent Laser Ranging and Imaging System (ILRIS-3D) data was acquired of individual tree crowns at olive (Olea europaea L.) plantations in Córdoba, Spain. In addition to conventional tripod-mounted ILRIS-3D scans, the unit was mounted on a platform (12 m above ground) to provide nadir (top-down) observations of the olive crowns. 24 structurally variable olive trees were selected for in-depth analysis. From the observed 3D laser pulse returns, quantitative retrievals of tree crown structure and foliage assemblage were obtained. Robust methodologies were developed to characterize diagnostic architectural parameters, such as tree height (r² = 0.97, rmse = 0.21 m), crown width (r² = 0.97, rmse = 0.13 m), crown height (r² = 0.86, rmse = 0.14 m), crown volume (r² = 0.99, rmse = 2.6 m³), and Plant Area Index (PAI) (r² = 0.76, rmse = 0.26 m²/m²). With the development of such LiDAR-based methodologies to describe vegetation architecture, the forestry, agriculture, and remote sensing communities are now faced with the possibility of replacing current labour-intensive inventory practices with, modern TLS systems. This research demonstrates that TLS systems can potentially be the new observational tool and benchmark for precise characterization of vegetation architecture for improved agricultural monitoring and management.