Significant patterns of fine-scale spatial genetic structure in a narrow endemic wind-dispersed tree species, <Emphasis Type="Italic">Cedrus brevifolia</Emphasis> Henry

Cedrus brevifolia is a narrowly distributed conifer species, currently limited to a single mountain in Cyprus, growing in restricted habitats on sites of different densities and sizes. This study assessed the influence of seed and pollen dispersal, as well as the effect of demographic and genetic features on the magnitude of fine-scale spatial genetic structure (SGS). Sampling was performed in 11 plots where 50 neighboring adult trees were sampled from each plot, while biparentally and paternally inherited genomes were used for analysis with microsatellites. Fine-scale SGS was significant but showed contrasting patterns among plots. Although the magnitude of SGS in C. brevifolia mainly results from restricted seed dispersal, short-distance pollen dispersal could also explain fine-scale SGS in some plots, which is rather uncommon in wind-pollinated conifer species. The lack of a general and consistent trend of SGS among plots and between genomes indicates that pollen and seed dispersal varies at plot level. The complex SGS patterns in C. brevifolia may result from the unequal ratio of male and female strobilies of trees within the same plots, at different reproductive periods. Demographic features such as habitat fragmentation did not influence the magnitude of SGS in C. brevifolia, whereas low tree aggregation reduced it. Further, the significant correlation observed between linkage disequilibrium (LD) and plots with significant SGS supports the assumption that under specific conditions, LD is likely to be caused by the magnitude of SGS.     

Microsatellite DNA analysis of spatial and temporal population structuring of <Emphasis Type="Italic">Phragmites australis</Emphasis> along the Hudson River Estuary

Phragmites australis is a perennial grass that has invaded wetlands of the northeastern United States over the past century. The Hudson River Estuary and surrounding watersheds are no exception in that populations of P. australis have spread dramatically along its shores and tributaries in the past 40 years. Recent studies have shown that genetically variable populations of P. australis can spread by seed dispersal in addition to clonal mechanisms. It is important to characterize the genetic variation of Hudson River populations as part of a management strategy for this species to determine the mechanisms by which its spreads and colonizes new habitats, particularly those with frequent anthropogenic disturbances. The goals of this study were to quantify levels of genetic variation and structuring in Hudson River populations of P. australis using microsatellite DNA analysis. A total of 354 culms of P. australis were collected from nine locations ranging from Albany, New York to Staten Island, New York in the summers of 2004 (N = 174) and 2011 (N = 180). Microsatellite data from eight loci indicated that the Hudson River Estuary has some of the highest levels of genetic variation of all U. S. Atlantic Coast regions containing P. australis. Gene diversity (Hs) across all loci in the 2004 collection was 0.45 (±0.02) and that of the 2011 collection was 0.47 (±0.07). Patches within sample sites were rarely monoclonal and had multiple genetic phenotypes. Moran’s Identity tests indicated that individuals within a patch were closely related, whereas little genetic relatedness was evident among individuals from sample sites >1 km apart. Spatial structuring was also not evident in autospatial correlation and principle coordinate analyses. These findings suggest that genetic diversity is maintained within stands by sexual reproduction and that seeds are important in dispersal of P. australis across the Hudson River Estuary. Ample habitats are available for establishment of new Phragmites stands due to high levels of anthropogenic disturbance from populations living along the Estuary. Wildlife managers should focus on monitoring habitats that provide seedbed for Phragmites and promote land use practices that prevent soil disturbance and establishment of new stands.     

Dispersal of remnant endangered trees in a fragmented and disturbed forest by frugivorous birds

Most endangered plant species in a fragmented forest behave as a unique source population, with a high dependence on frugivorous birds for recruitment and persistence. In this study, we combined field data of dispersal behavior of birds and GIS information of patch attributes to estimate how frugivorous birds could affect the effective dispersal pattern of Chinese yew (Taxus chinensis) in a fragmented and disturbed forest. Nine bird species were observed to visit T. chinensis trees, with Urocissa erythrorhyncha, Zoothera dauma and Picus canus being the most common dispersers. After foraging, six disperser species exhibited different perching patterns. Three specialist species, P. canus, Turdus hortulorum, and Z. dauma stayed in the source patch, while three generalist species, U. erythrorhyncha, Hypsipetes mcclellandii, and H. castanonotus, could perch in bamboo patches and varied in movement ability due to body size. As a consequence of perching, dispersers significantly contributed to the seed bank, but indirectly affected seedling recruitment. Moreover, the recruitment of T. chinensis was also affected by patch attributes in a fragmented forest (distances to source patch, patch type, size). Our results highlighted the ability of unique source population regeneration of T. chinensis in a fragmented forest, with high dependence on both frugivorous birds and patch attributes, which should be considered in future planning for forest management and conservation.     

Fine-scale spatial genetic structure in the frankincense tree <Emphasis Type="Italic">Boswellia papyrifera</Emphasis> (Del.) Hochst. and implications for conservation

The fine-scale genetic structure and how it varies between generations depends on the spatial scale of gene dispersal and other fundamental aspects of species’ biology, such as the mating system. Such knowledge is crucial for the design of genetic conservation strategies. This is particularly relevant for species that are increasingly fragmented such as Boswellia papyrifera. This species occurs in dry tropical forests from Ethiopia, Eritrea and Sudan and is an important source of frankincense, a highly valued aromatic resin obtained from the bark of the tree. This study assessed the genetic diversity and fine-scale spatial genetic structure (FSGS) of two cohorts (adults and seedlings) from two populations (Guba-Arenja and Kurmuk) in Western Ethiopia and inferred intra-population gene dispersal in the species, using microsatellite markers. The expected heterozygosity (H _E) was 0.664–0.724. The spatial analyses based on kinship coefficient (F _ij) revealed a significant positive genetic correlation up to a distance of 130 m. Spatial genetic structure was relatively weak (Sp = 0.002–0.014) indicating that gene dispersal is extensive within the populations. Based on the FSGS patterns found, we estimate indirectly gene dispersal distances of 103 and 124 m for the two populations studied. The high heterozygosity, the low fixation index and the low Sp values found in this study are consistent with outcrossing as the (predominant) mating system in B. papyrifera. We suggest that seed collection for ex situ conservation and reforestation programmes of B. papyrifera should use trees separated by distances of at least 100 m but preferably 150 m to limit genetic relatedness among seeds from different trees.     

Understanding the effects of isolation on seed and pollen flow,spatial genetic structure and effective population size of the dioecious tropical tree species <Emphasis Type="Italic">Myracrodruon urundeuva</Emphasis>

This study examines the levels of gene flow, the distance and the patterns of pollen and seed dispersal, the intra-population spatial genetic structure (SGS) and the effective population size of a spatially isolated Myracrodruon urundeuva population using five microsatellite loci. The study was carried out in the Paulo de Faria Ecological Station, São Paulo State, Brazil and included the sampling and mapping of 467 adult-trees and 149 juveniles. Open-pollinated seeds (514) from 29 seed-trees were also sampled and genotyped. Significant SGS was detected in both adult (S _p  = 0.0269) and juveniles trees (S _p  = 0.0246), indicating short-distance seed dispersal. Using maternity analysis, all juveniles had the mother-tree assigned within the stand. A father-tree within the stand was also assigned for 97.3% of the juveniles and 98.4% of offspring. The average pollen dispersal distance measured in juveniles \( \left( {\hat{\delta } = 1 3 8\pm 1 6 9 {\text{ m}},{\text{ mean}} \pm {\text{SD}}} \right) \) and offspring \( \left( {\hat{\delta } = 2 5 2\pm 20 4 {\text{ m}}} \right) \) were higher than the average seed dispersal distance measured in juveniles \( \left( {\hat{\delta } = 1 2 4\pm 1 50{\text{ m}}} \right) \). About 70% of the pollen from juveniles and 51% from offspring traveled less than 200 m and, 72% of the seeds traveled less than 50 m. The effective population size of the studied sample indicates that the 467 adult-trees and 145 juveniles correspond respectively to 335 and 63 individuals that are neither inbred nor relatives. The results are discussed in relation to their impact on seed collection practices and genetic conservation.     

Breeding system,gene dispersal and small-scale spatial genetic structure of a threatened food tree species, <Emphasis Type="Italic">Pentadesma butyracea</Emphasis> (Clusiaceae) in Benin

Pentadesma butyracea Sabine, a rain forest food tree species, plays a vital role in the socio-economic livelihood of some West African rural communities due to its various products. However, its scattered populations are threatened in Benin. Defining appropriate conservation strategies requires a good knowledge of mating patterns and their consequences for population genetics. The outcrossing rate, levels of correlated paternity and fine-scale spatial genetic structure of adults and maternal sibships were estimated for one small population and three large populations in Benin using microsatellite markers. Similar outcrossing rates (88–95%) were found in all populations, showing that P. butyracea is mainly an outbreeding species. We found no evidence of inbreeding depression from a decay of inbreeding with age. The spatial genetic structure within the large populations (Sp statistic?=?0.003–0.038) was consistent with isolation-by-distance expectations, showing that gene dispersal is spatially limited. Limited pollen dispersal is highlighted by the decay of the degree of correlated paternity between sibships with spatial distance. The mean pollen dispersal distance was estimated between 50 m and 450 m, but up to 21% pollen may migrate from external sources. The smallest population displayed slightly higher correlated paternity than the large populations (r _p ?=?0.37 vs. r _p ?=?0.17–0.30). In conclusion, our results suggest that small populations may show a reduction in sire numbers in seed, while the fragmented populations, large and small, are connected through gene flow. There is little inbreeding and no evidence of inbreeding depression.     

Allozyme Polymorphism of Swiss Stone Pine <Emphasis Type="Italic">Pinus cembra</Emphasis> L. in Mountain Populations of the Alps and the Eastern Carpathians

Swiss stone pine Pinus cembra L. is a species with fragmented range, occurring in the Alpine-East Carpathian mountain system. Seeds of P. cembra are dispersed by nutcrackers, which offers potential possibilities for gene exchange among populations. Using isozyme analysis, we have examined five samples from two parts of the Swiss stone pine range: the Alps (Switzerland and Austria) and the Carpathians (two samples from the northern macroslope of the Gorgany Ridge, Eastern Carpathians, Ivano-Frankivs'ka oblast and one sample from Zakarpats'ka oblast of Ukraine). The allele frequencies of 30 isozyme loci, coding for enzymes ADH, FDH, FEST, GDH, GOT, IDH, LAP, MNR, MDH, PEPCA, 6-PGD, PGI, PGM, SDH, SKDH, SOD, were analyzed using cluster analysis and Principal Component Analysis. Two clusters, corresponding to the isolated Alpine and Carpathian parts of the range, were found. The main contribution to these differences were made by loci Adh-1, Adh-2, Fest-2, Lap-3, Mdh-4, and Sod-4. The interpopulation differentiation proved to be somewhat higher than that typical for pines (F_ST = 7.4%), but within the limits characteristic for taxonomically close species. Thus, isolation of the populations did not lead to their marked differentiation, which may be explained by gene flow and balancing selection, which equalizes gene frequencies across the fragmented species area. Interlocus (F_ST heterogeneity (from 0.003 to 0.173) suggests adaptive significance of some of the allozyme polymorphisms or linkage of some loci with adaptive genes. The Carpathian populations were shown to have higher gene diversity than the Alpine ones (expected heterozygosities 0.095–0.114 and 0.060–0.080, respectively). A deficiency of heterozygotes (as compared to the Hardy-Weinberg proportions), observed in the embryo sample, was probably explained by inbreeding. The reduction in the area of Carpathian pine forests in Holocene, caused by the global climatic changes and the anthropogenic impact, is hazardous for the gene pool of the species. The maintenance of genetic uniqueness of both Carpathian populations of P. cembra in general, and individual stands in particular, requires special measures for protection of Swiss stone pine in the Eastern Carpathians.     

Habitat loss exacerbates regional extinction risk of the keystone semiarid shrub <Emphasis Type="Italic">Ziziphus lotus</Emphasis> through collapsing the seed dispersal service by foxes (<Emphasis Type="Italic">Vulpes vulpes</Emphasis>)

Habitat loss and landscape degradation affect animal-mediated seed dispersal, often collapsing the regeneration of endangered plant species and habitats in anthropogenic landscapes. We first compared the role of red fox and other vertebrates as seed disperser for the keystone scrub Ziziphus lotus. Because it turned out that foxes are the major Z. lotus dispersers, we investigated how fox activity and dispersal service relate to habitat loss and landscape alteration in the threatened Ziziphus semiarid scrublands, a priority habitat for conservation in Europe. Considering its opportunistic behavior, we hypothesized that landscape features should affect moderately fox abundance, while influence in a large extent its dispersal service. Accordingly, we predicted that a substantial decline in Ziziphus fruit consumption rather than in disperser activity would be responsible for seed dispersal collapse under severe habitat loss. We evaluated fox activity and dispersal service in 17 populations of Z. lotus spread through the range of its habitat in Spain and found within landscapes with different land-use intensity. We certified the collapse of the dispersal service by fox under severe habitat loss and confirmed that fox activity was less affected by habitat loss or landscape alteration than consumption of Ziziphus fruits. Consequently, the decline of consumption of Ziziphus fruits under severe habitat loss triggers the collapse of its seed dispersal. Results suggest that without increase of the remnant areas other managements may not suffice to achieve seed dispersal and habitat restoring. Dispersal service and natural regeneration in many Ziziphus habitat remnants will possibly cease in the future if habitat loss continues.     

Microsatellite analysis to estimate realized dispersal distance in <Emphasis Type="Italic">Phragmites</Emphasis><Emphasis Type="Italic">australis</Emphasis>

An understanding of the mean and maximum dispersal distances of target species and subsequent scaling of management efforts to dispersal distance can be key in slowing, containing, or eradicating invasive species. However, dispersal distance is often difficult to measure. Patterns of genetic relatedness can be interpreted to understand realized genetic dispersal distances, which can then be applied to management. We analyzed patterns of microsatellite relatedness using Mantel correlograms and used them to estimate realized dispersal distance for the invasive wetland grass, Phragmites australis. We found that genetic relatedness declined quickly with increasing distance, decreasing to the level of the mean subestuary genetic relatedness by 100 m and to nearly zero by 500 m. We interpret this to indicate that most dispersal is <100 m and very little dispersal extends beyond 500 m. This suggests that management of P. australis may need to consider dispersal from stands up to 500 m from an area that is being managed, perhaps at the scale of whole subestuaries. Results of this study demonstrate that analysis of dispersal patterns can be used to develop landscape-scale approaches to the management of invasive species.     

Temporal variations in seed dispersal patterns of a bird-dispersed tree, <Emphasis Type="Italic">Swida controversa</Emphasis> (Cornaceae), in a temperate forest

The seed dispersal patterns of bird-dispersed trees often show substantial seasonal and annual variation due to temporal changes in frugivorous bird and bird-dispersed fruit distributions. Elucidating such variation and how it affects plant regeneration is important for understanding the evolution and seed dispersal maintenance strategies of these plants. In this study, we investigated the seed dispersal quantity and distance of a bird-dispersed plant, Swida controversa, for 2 years and detected large seasonal variations in dispersal pattern. Early in the fruiting season, short seed dispersal distance and large amounts of fruit consumption by birds (seed dispersal quantity) were observed. In contrast, late in the fruiting season, a long seed dispersal distance and small seed dispersal quantity were observed. This relationship between seed dispersal distance and quantity may help to maintain constant seed dispersal effectiveness during the long S. controversa fruiting season. Annual variation was also detected for both seed dispersal quantity and distance. More effective seed dispersal was achieved in the masting year, because both seed dispersal quantity and distance were greater than that in the non-masting year. These seed dispersal dynamics may contribute to the evolution and maintenance of S. controversa masting behavior. Thus, we identified substantial temporal variation on both seasonal and annual scales in the seed dispersal pattern of a bird-dispersed plant. The temporal variation in seed dispersal pattern revealed in this study probably plays a substantial role in the life history and population dynamics of S. controversa.     

Hybrid plants preserve unique genetic variation in the St Helena endemic trees <Emphasis Type="Italic">Commidendrum rotundifolium</Emphasis> DC Roxb. and <Emphasis Type="Italic">C. spurium</Emphasis> (G.Forst.) DC

The island of St Helena in the South Atlantic Ocean has a rich endemic flora, with 10 endemic genera and 45 recognised endemic species. However, populations of most endemic species have undergone dramatic reductions or extinction due to over-exploitation, habitat destruction and competition from invasive species. Consequently, endemic species are likely to have lost genetic variation, in some cases to extreme degrees. Here, the entire extant wild populations and all planted trees in seed orchards, of two critically endangered species in the endemic genus Commidendrum (Asteraceae), C. rotundifolium and C. spurium, were sampled to assess levels of genetic variation and inbreeding. Six new microsatellite loci were developed from next-generation sequence data, and a total of 190 samples were genotyped. Some seed orchard trees contained alleles from both wild C. rotundifolium and C. spurium indicating they could be hybrids and that some backcrossing may have occurred. Some of these trees were more similar to C. rotundifolium than C. spurium both genetically and morphologically. Importantly, allelic variation was detected in the putative hybrids that was not present in wild material. C. rotundifolium is represented by just two individuals one wild and one planted and C. spurium by seven, therefore the seed orchard trees comprise an important part of the total remaining genetic diversity in the genus Commidendrum.     

Seed Dispersal by Primates and Implications for the Conservation of a Biodiversity Hotspot,the Atlantic Forest of South America

Primates play a fundamental role as seed dispersers, particularly in tropical rainforests. Because defaunation and fragmentation are leading several primate species to local extinction, it is fundamental to understand the role of primates as effective seed dispersers. Here we present a systematic review of studies of seed dispersal by primates in a biodiversity hotspot, the Atlantic Forest of South America, to 1) highlight gaps in our knowledge, 2) determine species richness and proportion of seed species dispersed, and 3) test the relationship between primate body size and the size of dispersed species. Our review found 79 studies of the diet of six ecospecies (Callithrix, Leontopithecus, Callicebus, Sapajus, Alouatta, Brachyteles) but only 20 of these report information on seed dispersal, and none of these are on Callithrix or Callicebus. We found a strong bias in the distribution of species and regions, with most of the studies concentrated in southeastern Brazil. All ecospecies dispersed a large proportion of the seed species they handled (72.1–93.6%). Brachyteles dispersed the highest diversity of plants (N = 73), followed by Sapajus (N = 66), Leontopithecus (N = 49), and Alouatta (N = 26). Although we found no significant relationship between primate body size and the size of seeds dispersed, Brachyteles disperse a higher diversity of large-seeded species than smaller-bodied primates. These results suggest that the local extinction of large primate species may lead to dramatic changes in the plant community, as many large-seeded plants are inaccessible to smaller arboreal frugivores. We propose guidelines for future research on primate seed dispersal to enable the evaluation of seed dispersal effectiveness and to improve our understanding of the fundamental role of primates in this key ecosystem process.     

Effective gene flow in a historically fragmented area at the southern edge of silver fir (<Emphasis Type="Italic">Abies alba</Emphasis> Mill.) distribution

Fragmented populations at the edges of a species’ distribution can be highly exposed to the loss of genetic variation, unless sufficient gene flow maintains their genetic connectivity. Gene movements leading to successful establishment of external gametes (i.e. effective gene flow) into fragmented populations can solely be assessed by investigating the origin of natural regeneration. This study is focused on studying gene flow patterns in two silver fir stands in Central Apennines, where the species has a highly fragmented distribution. By using nuclear and chloroplast microsatellite markers, we investigated genetic variation, fine-scale spatial genetic structure, effective gene flow rates and large-scale connectivity characterizing both stands. Similar levels of genetic variation and low genetic differentiation between stands (F _ST = 0.005) and across generations were found, coupled with low inbreeding and weak to absent SGS in the adult cohort (Sp < 0.003). On the other hand, substantial differences between the two stands in terms of gene flow rates were observed. Irrespective of the parentage approach used, higher gene flow rates were found in the stand located at the upper silver fir altitudinal limit, especially for seed-mediated gene flow (0.79 in the upper stand vs. 0.48 in the lower stand). Conversely, the lower stand was characterized by a higher reproductive dominance of local adults. Our findings suggest that, despite similar levels of genetic variation and generally high gene flow rates, different processes may be acting on the two stands, reflecting varying ecological conditions.     

Genetic Differentiation and Demographic History of the Northern Rufous Mouse Lemur (<Emphasis Type="Italic">Microcebus tavaratra</Emphasis>) Across a Fragmented Landscape in Northern Madagascar

Phylogeographic barriers, together with habitat loss and fragmentation, contribute to the evolution of a species’ genetic diversity by limiting gene flow and increasing genetic differentiation among populations. Changes in connectivity can thus affect the genetic diversity of populations, which may influence the evolutionary potential of species and the survival of populations in the long term. We studied the genetic diversity of the little known Northern rufous mouse lemur (Microcebus tavaratra), endemic to Northern Madagascar. We focused on the population of M. tavaratra in the Loky–Manambato region, Northern Madagascar, a region delimited by two permanent rivers and characterized by a mosaic of fragmented forests. We genotyped 148 individuals at three mitochondrial loci (D-loop, cytb, and cox2) in all the major forests of the study region. Our analyses suggest that M. tavaratra holds average genetic diversity when compared to other mouse lemur species, and we identified two to four genetic clusters in the study region, a pattern similar to that observed in another lemur endemic to the region (Propithecus tattersalli). The main cluster involved samples from the two mountain forests in the study region, which were connected until recently. However, the river crossing the study region does not appear to be a strict barrier to gene flow in M. tavaratra. Finally, the inferred demographic history of M. tavaratra suggests no detectable departure from stationarity over the last millennia. Comparisons with codistributed species (P. tattersalli and two endemic rodents, Eliurus spp.) suggest both differences and similarities in the genetic clusters identified (i.e., barriers to species dispersal) and in the inferred demographic history. These comparisons suggest that studies of codistributed species are important to understand the effects of landscape features on species and to reconstruct the history of habitat changes in a region.     

Role of indehiscent pericarp in formation of soil seed bank in five cold desert Brassicaceae species

The dispersal and germination unit of some Brassicaceae species is the fruit, and we hypothesized that it could affect germination phenology and promote formation of a soil seed bank. We determined the effects of the indehiscent pericarp on germination and longevity of buried seeds of five Brassicaceae species native to cold deserts of central Asia. Germination phenology (seedling emergence) was monitored for intact dispersal units and isolated seeds of Chorispora sibirica, Goldbachia laevigata, Spirorrhynchus sabulosus, Tauscheria lasiocarpa (annuals), and Sterigmostemum fuhaiense (perennial) at natural temperatures in watered and non-watered (natural precipitation) soil. Intact dispersal units and isolated seeds were buried under natural conditions and exhumed at regular intervals for 35 months to monitor germination, viability and moisture content of isolated seeds, seeds in dispersal units, and seeds removed from dispersal units after burial. Isolated seeds of Goldbachia, Spirorrhynchus, and Tauscheria germinated only the first autumn and those of Chorispora and Sterigmostemum the first autumn and first spring, with higher germination percentages in all species in watered than in non-watered soil. A high percentage of seeds in buried dispersal units of Chorispora, Goldbachia, and Sterigmostemum was viable after 35 months, and seeds exhibited a 6-month dormancy cycle, being non-dormant only in autumn and spring. Seeds in buried dispersal units of Spirorrhynchus and Tauscheria germinated when exhumed in the first spring, but all non-germinated seeds were dead after 1 year. Thus, the presence of the pericarp allows Chorispora, Goldbachia, and Sterigmostemum to form a persistent seed bank but not Spirorrhynchus and Tauscheria.     

Survival possibilities of the dragonfly <Emphasis Type="Italic">Aeshna viridis</Emphasis> (Insecta,Odonata) in southern Sweden predicted from dispersal possibilities

We use public records from 1980 to 2014 to analyse survival of the EU Annex IV species Aeshna viridis in Sweden, a dragonfly strongly associated with the plant Stratiotes aloides. We clustered localities with S. aloides based on assumed dispersal abilities of A. viridis, using a dispersing radius of 2–100 km, calculating the proportion of sites with S. aloides that A. viridis is able to reach. If mean dispersal capability is high (40 km or above) 92.6 % or more of the localities are connected. For a good disperser, the probability of long-time survival is good. We further analysed the species richness of other Odonata and aquatic plants at 98 localities from the dataset. A. viridis co-occurred with more Odonata in the presence of S. aloides and running water but not in lakes. S. aloides sites had a higher number of other aquatic plants. Area had no impact on the occurrence of the species. For the present situation we surveyed 32 localities with known occurrence of the species. Only half of the sites for S. aloides contained any specimens while A. viridis occurred in the same number of sites. The species co-occurred in only 8 of 32 sites. In four sites A. viridis larvae appeared among Menyanthes trifoliata, Phragmites australis, Potamogeton natans and Sphagnum spp., indicating that at high latitudes A. viridis breeds among other species. Indirect monitoring based only on S. aloides would underestimate the number of populations of the dragonfly.     

Fruit and Seed Dispersal of <Emphasis Type="Italic">Salvia</Emphasis> L. (Lamiaceae): A Review of the Evidence

The seed dispersal mechanisms of Salvia species are reviewed, with particular attention to quantitative or experimental evidence of dispersal. Despite having rather uniform fruit morphology, Salvia has several dispersal mechanisms: dispersal of mericarps by water (hydrochory), wind (anemochory), animals (zoochory) or gravity (barochory). Cases of myrmecochory are highlighted, along with dispersal by the plant itself via springy or hygroscopic pedicels. Despite having no visible means of dispersal, many Salvia species disperse for short to medium distances. Many gaps in our knowledge of dispersal exist, despite the fact that knowledge of dispersal mechanisms is critical in evaluating invasive potential, conservation status, usefulness in habitat restoration, and geographic distribution.     

Identification of candidate genes of QTLs for seed weight in <Emphasis Type="Italic">Brassica napus</Emphasis> through comparative mapping among <Emphasis Type="Italic">Arabidopsis</Emphasis> and <Emphasis Type="Italic">Brassica</Emphasis>species

Background

Map-based cloning of quantitative trait loci (QTLs) in polyploidy crop species remains a challenge due to the complexity of their genome structures. QTLs for seed weight in B. napus have been identified, but information on candidate genes for identified QTLs of this important trait is still rare.

Results

In this study, a whole genome genetic linkage map for B. napus was constructed using simple sequence repeat (SSR) markers that covered a genetic distance of 2,126.4 cM with an average distance of 5.36 cM between markers. A procedure was developed to establish colinearity of SSR loci on B. napus with its two progenitor diploid species B. rapa and B. oleracea through extensive bioinformatics analysis. With the aid of B. rapa and B. oleracea genome sequences, the 421 homologous colinear loci deduced from the SSR loci of B. napus were shown to correspond to 398 homologous loci in Arabidopsis thaliana. Through comparative mapping of Arabidopsis and the three Brassica species, 227 homologous genes for seed size/weight were mapped on the B. napus genetic map, establishing the genetic bases for the important agronomic trait in this amphidiploid species. Furthermore, 12 candidate genes underlying 8 QTLs for seed weight were identified, and a gene-specific marker for BnAP2 was developed through molecular cloning using the seed weight/size gene distribution map in B. napus.

Conclusions

Our study showed that it is feasible to identify candidate genes of QTLs using a SSR-based B. napus genetic map through comparative mapping among Arabidopsis and B. napus and its two progenitor species B. rapa and B. oleracea. Identification of candidate genes for seed weight in amphidiploid B. napus will accelerate the process of isolating the mapped QTLs for this important trait, and this approach may be useful for QTL identification of other traits of agronomic significance.

     

African Cycad Ecology,Ethnobotany and Conservation: A Synthesis

Africa hosts a rich assemblage of cycads: 66 Encephalartos species, Stangeria eriopus and Cycas thouarsii. Most Encephalartos and S. eriopus adults appear to be fire-tolerant, and certain Encephalartos species may be fire-dependent. Four Encephalartos species and S. eriopus are primarily insect-pollinated. African cycad populations typically have sex ratios of 1:1, with very small populations often male-biased. Coning is typically infrequent and erratic, with many species exhibiting mast-seeding. Viable seed production in Encephalartos populations tends to decline with decreasing population size, and seed predation by weevils is common. Seed dispersal in Encephalartos is usually localized, but vertebrates may facilitate dispersal over longer distances. Stem material of 25 Encephalartos species and S. eriopus is used for traditional medicine, primarily in South Africa. Two-thirds of Africa’s cycad species are threatened, with four species already Extinct in the Wild. The illegal acquisition of cycads from wild populations is the principle threat to their persistence. Further research is recommended on seed and fire ecology, population dynamics, and the outcomes of conservation interventions.     

Tree squirrel habitat selection and predispersal seed predation in a declining subalpine conifer

Differential responses by species to modern perturbations in forest ecosystems may have undesirable impacts on plant-animal interactions. If such disruptions cause declines in a plant species without corresponding declines in a primary seed predator, the effects on the plant could be exacerbated. We examined one such interaction between Pinus albicaulis (whitebark pine), a bird-dispersed, subalpine forest species experiencing severe population declines in the northern part of its range, and Tamiasciurus hudsonicus (red squirrel), an efficient conifer seed predator, at 20 sites in two distinct ecosystems. Hypotheses about squirrel habitat preferences were tested to determine how changes in forest conditions influence habitat use and subsequent levels of predispersal cone predation. We performed habitat selection modeling and variable ranking based on Akaike’s information criterion; compared the level and variance of habitat use between two forest types (P. albicaulis dominant and mixed conifer); and modeled the relationship between P. albicaulis relative abundance and predispersal cone predation. T. hudsonicus did not demonstrate strong habitat preference for P. albicaulis, and thus, declines in the pine were not met with proportional declines in squirrel habitat use. P. albicaulis habitat variables were the least important in squirrel habitat selection. Squirrel habitat use was lower and varied more in P. albicaulis-dominant forests, and predispersal cone predation decreased linearly with increasing P. albicaulis relative abundance. In Northern Rocky Mountain sites, where P. albicaulis mortality was higher and abundance lower, squirrel predation was greater than in Central Rocky Mountain sites. In ecosystems with reduced P. albicaulis abundance, altered interactions between the squirrel and pine may lead to a lower proportion of P. albicaulis contributing to population recruitment because of reduced seed availability. Reducing the abundance of competing conifers will create suboptimal squirrel habitat, thus lowering cone predation in P. albicaulis and ensuring more seeds are available for avian dispersal.