Growth strategy of the stoloniferous rattan Calamus javensis in Mt. Halimun, Java

Calamus javensis is a widespread understorey rattan in Southeast Asia and is one of the dominant rattan species in Mt. Halimun National Park, West Java. This species can establish clumps either sexually with seeds or clonality with stolons. To analyze the role of sexual reproduction and clonality for clump establishment in C. javensis, we studied the vegetative and genetic structures of the population. Totals of 2,777 ramets comprising 1,321 clumps were found in three 0.16 ha plots. The number of ramets per clump showed reverse J-shaped distribution with a maximum of 15. Clustering and stoloniferous ramets accounted for 62 and 20% of all ramets, respectively. This indicates that C. javensis is actively engaged in clustering clonal growth. The longest stem was 14 m although 75% of all stems were shorter than 1 m long. The stolon ranged from 6 to 538 cm in length, which decreased the local density of ramets. Using randomly amplified polymorphic DNA (RAPD) analysis, we obtained 56 polymorphic bands for 118 clumps sampled from one of the plots. All samples showed different RAPD banding patterns, except one pair at a distance of 225 cm from each other. The genetic similarity among samples closer than 10 m was significantly higher than the expected value from a purely random distribution. These results suggest that most separate clumps are established by recruitment from seeds, and most seeds dispersed near mother plants. Hence, in C. javensis, clonality is more a growth strategy to increase the size of the genet than a dispersion-propagation strategy to expand the habitat.     

Clonal Diversity and Fine‐scale Genetic Structure in a High Andean Treeline Population

Clonal propagation becomes more abundant with increasing altitudes as environmental conditions worsen. To date, little attention has been paid to the way in which clonal propagation affects genetic diversity and the fine‐scale spatial genetic structure (FSGS) of clonal alpine trees. An AFLP study was undertaken to quantify the clonal and genetic diversity and FSGS of the vulnerable treeline species Polylepis reticulata in Ecuador. We successfully genotyped 32 and 75 ramets within 4 m × 100 m (coarse scale) and 4 m × 4 m (fine scale) transects of one population, respectively. Higher genotypic diversity was detected at the coarse scale than at the fine scale, while lower genetic diversity was detected for P. reticulata than other Polylepis spp. at both scales. Significantly stronger FSGS was detected at the ramet level than the genet level for P. reticulata within a spatial distance of 3 m. The studied P. reticulata population showed pronounced FSGS (Sp = 0.012 at the genet level, a statistic reflecting declining pairwise kinship with distance) revealed restricted gene dispersal, which implies restricted seed dispersal for this population, assuming pollen flow is as extensive as that described for other wind‐pollinated tree species. Our results revealed that clonal diversity is a function of both sample size and the spatial scale of the sampling area. The findings highlights that clonal propagation has affected FSGS within a spatial distance of 3 m for this species.     

Spatial genetic structure and restricted gene flow in a functionally dioecious fig, <Emphasis Type="Italic">Ficus pumila</Emphasis> L. var. <Emphasis Type="Italic">pumila</Emphasis> (Moraceae)

The mutualism between fig plants and fig wasps has been recognized as one of the most specialized systems of symbiosis. Figs are pollinated by their highly specific pollinating fig wasps, and the pollinating fig wasps are raised within the syconia of figs. Recent studies indicated a difference between monoecious and dioecious figs in the dispersal range of pollinating wasps, which has potential consequences for gene flow. In this study, we detected the gene-flow pattern of the dioecious climbing fig, Ficus pumila L. var. pumila, at both local and regional scales. At the local scale, spatial autocorrelation analysis indicated strong genetic structure at short distances, a pattern of limited gene flow. This result was also supported by a high inbreeding coefficient (F _IS = 0.287) and significant substructuring (F _ST = 0.060; P < 0.001). Further analysis indicated that the effective gene dispersal range was 1,211 m, and the relative contribution of seed dispersal was smaller than that of pollen dispersal. The inferred effective range of pollen dispersal ranged from 989 to 1,712 m, while the effective seed dispersal range was less than 989 m. Lack of long-distance dispersal agents may explain the limited seed dispersal. The high density of receptive fig trees was the most likely explanation for limited pollen dispersal, and the position of syconia and relatively low wind speed beneath the canopy may contribute to this phenomenon. At the regional scale, significant negative correlations (kinship coefficient F _ij ranging from −0.038 to −0.071) existed in all comparisons between the studied population and other populations, and the assignment test grouped almost all individuals of the studied population into a distinct cluster. Asynchronous flowering on the regional scale, which provides a barrier for the pollinating wasps to fly from the studied population to the other populations, is probably responsible for the limited gene flow on the regional scale.     

Variation in fine‐scale genetic structure and local dispersal patterns between peripheral populations of a South American passerine bird

The distribution of suitable habitat influences natal and breeding dispersal at small spatial scales, resulting in strong microgeographic genetic structure. Although environmental variation can promote interpopulation differences in dispersal behavior and local spatial patterns, the effects of distinct ecological conditions on within‐species variation in dispersal strategies and in fine‐scale genetic structure remain poorly understood. We studied local dispersal and fine‐scale genetic structure in the thorn‐tailed rayadito (Aphrastura spinicauda), a South American bird that breeds along a wide latitudinal gradient. We combine capture‐mark‐recapture data from eight breeding seasons and molecular genetics to compare two peripheral populations with contrasting environments in Chile: Navarino Island, a continuous and low density habitat, and Fray Jorge National Park, a fragmented, densely populated and more stressful environment. Natal dispersal showed no sex bias in Navarino but was female‐biased in the more dense population in Fray Jorge. In the latter, male movements were restricted, and some birds seemed to skip breeding in their first year, suggesting habitat saturation. Breeding dispersal was limited in both populations, with males being more philopatric than females. Spatial genetic autocorrelation analyzes using 13 polymorphic microsatellite loci confirmed the observed dispersal patterns: a fine‐scale genetic structure was only detectable for males in Fray Jorge for distances up to 450 m. Furthermore, two‐dimensional autocorrelation analyzes and estimates of genetic relatedness indicated that related males tended to be spatially clustered in this population. Our study shows evidence for context‐dependent variation in natal dispersal and corresponding local genetic structure in peripheral populations of this bird. It seems likely that the costs of dispersal are higher in the fragmented and higher density environment in Fray Jorge, particularly for males. The observed differences in microgeographic genetic structure for rayaditos might reflect the genetic consequences of population‐specific responses to contrasting environmental pressures near the range limits of its distribution.     

Genetic diversity in the blackberry rust pathogen, Phragmidium violaceum, in Europe and Australasia as revealed by analysis of SAMPL

Indigenous to Europe, the blackberry rust fungus Phragmidium violaceum was introduced to Australia and subsequently appeared in New Zealand, with the most recent authorised introductions to Australia specifically for the biological control of European blackberry. Markers for ‘selective amplification of microsatellite polymorphic loci’ (SAMPL) were developed for studying the population genetics of P. violaceum. Modification of one of the two SAMPL primers with a HaeIII adapter (H) revealed significantly greater levels of genetic variation than primers used to generate AFLPs, the latter revealing little or no variation among 25 Australasian and 19 European isolates of P. violaceum. SAMPL was used to describe genetic variation among these 44 isolates of P. violaceum from 51 loci generated using primer pairs (GACA)₄ + H–G and R1 + H–G. The European isolates were more diverse than Australasian isolates, with 37 and 22 % polymorphic loci, respectively. Cluster analysis revealed geographic clades, with Australasian isolates forming one cluster separated from two clusters comprising the European isolates. However, low bootstrap support at these clades suggested that Australian isolates had not differentiated significantly from European isolates since the first record of P. violaceum in Australia in 1984. In general, the results support two hypotheses. First, that the population of P. violaceum in Australia was founded from a subset of individuals originating from Europe. Second, that P. violaceum in New Zealand originated from the Australian population of P. violaceum, probably by wind dispersal of urediniospores across the Tasman Sea. The application of SAMPL markers to the current biological control programme for European blackberry is discussed.     

Patterns of pollen dispersal in a small population of the Canarian endemic palm (Phoenix canariensis)

The genetic diversity of small populations is greatly influenced by local dispersal patterns and genetic connectivity among populations, with pollen dispersal being the major component of gene flow in many plants species. Patterns of pollen dispersal, mating system parameters and spatial genetic structure were investigated in a small isolated population of the emblematic palm Phoenix canariensis in Gran Canaria island (Canary Islands). All adult palms present in the study population (n=182), as well as 616 seeds collected from 22 female palms, were mapped and genotyped at 8 microsatellite loci. Mating system analysis revealed an average of 5.8 effective pollen donors (N_ep) per female. There was strong variation in correlated paternity rates across maternal progenies (ranging from null to 0.9) that could not be explained by the location and density of local males around focal females. Paternity analysis revealed a mean effective pollen dispersal distance of ∼71 m, with ∼70% of effective pollen originating from a distance of <75 m, and 90% from <200 m. A spatially explicit mating model indicated a leptokurtic pollen dispersal kernel, significant pollen immigration (12%) from external palm groves and a directional pollen dispersal pattern that seems consistent with local altitudinal air movement. No evidence of inbreeding or genetic diversity erosion was found, but spatial genetic structure was detected in the small palm population. Overall, the results suggest substantial pollen dispersal over the studied population, genetic connectivity among different palm groves and some resilience to neutral genetic erosion and subsequently to fragmentation.     

Allozyme diversity in the federally threatened golden paintbrush, <Emphasis Type="Italic">Castilleja levisecta</Emphasis> (Scrophulariaceae)

Castilleja levisecta (Scrophulariaceae), the golden paintbrush, is an insect-pollinated herbaceaous perennial found in the Pacific Northwest. Currently restricted to two island populations off British Columbia and nine populations (eight on islands) in Washington, C. levisecta is a rare species threatened with extinction. Allozymes were used to describe genetic diversity and structure in these eleven populations. Despite its threatened status and small geographic range, exceptionally high levels of genetic diversity are maintained within C. levisecta. All sixteen of the loci resolved were polymorphic within the species (P_s=100%), while the mean percentage of loci polymorphic within populations (P_p) was 65.7%. The mean number of alleles per polymorphic locus (AP_s) was 2.94 within the species and averaged 2.38 within populations (AP_p). Genetic diversity (H_es) was 0.285 for the species, whereas mean population genetic diversity (H_ep) was 0.213. Smaller populations had, on average, fewer observed alleles and less genetic diversity. A significant negative correlation (r = –0.72) was found between genetic identity and geographic distance, indicating reduced gene flow between distant populations. The most geographically isolated population was one of the larger populations, one of the most genetically diverse and the most genetically divergent. A wide range of pairwise population genetic identities (I = 0.771 – 0.992) was found, indicating considerable genetic divergence between some populations. Overall, 19% of the total genetic diversity was distributed among populations. Results of this survey indicate that genetic augmentation of existing populations is unnecessary. The high allelic diversity found for the species and within its populations holds promise for conservation and restoration efforts to save this rare and threatened plant species.     

The extent of clonality in large stands of Lycopodium annotinum L.

In the Rothaargebirge (Northrhine-Westphalia) the interrupted club moss (Lycopodium annotinum L.) often grows in large (maximum size of patches observed: 18,000 m²) and dense (club moss cover 60–90%) clusters. By DNA amplification fingerprinting (DAF) analysis it was shown in three populations comprising a total of 69 samples that the clusters are of great genetical uniformity. Based on data from 47 polymorphic loci amplified with 13 primers 11 multilocus genotypes were identified, nine in one population and one per population in the other two. The data were subjected to similarity analysis, generating Jaccard′s similarity coefficients, on the basis of which cluster analysis was performed. Calculation of Nei's genetic diversity (1987) resulted in a mean value of 0.77 over all samples and a mean within populations diversity of 0.3. Corrected G′_ST value for the fraction of diversity among the populations was 0.7. Two out of three sites are most probably formed by one clone only. As the annual growth rate of the shoots is known, it has to be stated that the stands under investigation are at least 80–90 years old. Taking into consideration that annual accretion is virtually non-existent following forest thinning measures, it becomes very likely that the club moss plants are approximately as old as the trees of their forests (150–180 years). This hypothesis is supported by the observation that within the forests only large (i.e. old) stands, but no single shoots (i.e. young individuals) of the club moss exist. Thus one can conclude that in undisturbed forests no sexual reproduction of L. annotinum takes place.     

Fine-scale spatial structure of genets and sexes in the dioecious plant <Emphasis Type="Italic">Dioscorea japonica</Emphasis>, which disperses by both bulbils and seeds

To understand the evolution of clonal reproduction and the diversity of clonal plants, it is necessary to clarify the characteristics of each clonal habit. There has been little research on whether bulbils alter spatial genetic structure (SGS) because of the lack of connection to maternal ramets. We used simple-sequence-repeat (SSR) markers to determine the fine-scale SGS of the dioecious plant Dioscorea japonica, which disperses both as bulbils and as seeds. We also evaluated the contributions of sexual and clonal reproduction and tested for spatial sex segregation (SSS). We discovered 111 genets from 394 ramets in a 2.8-ha plot. Genotypic richness (R = 0.28) and clonal diversity (Simpson’s D = 0.94, Fager’s E = 0.90) were high. We did not find SSS, suggesting that the population does not suffer from a shortage of mating pairs due to clonal reproduction. The Sp values revealed moderate SGS at the genet level (Sp = 0.013–0.014), and the genets intermingled at a local scale. Significant SGS at the ramet level showed that ramets within the same genet tended to aggregate. We also found a skewed clonal spatial distribution. The spatial extent of genets was positively correlated with the number of ramets within a genet. The contribution of bulbil production to the variance of parent–offspring gene dispersal was about one–fifth the contribution from sexual reproduction. These results suggest that the dispersal via bulbils affects the SGS in D. japonica, although its contribution to gene dispersal is small compared to the contribution of sexual reproduction.     

Novel polymorphic microsatellite loci and patterns of pollen-mediated gene flow in an ex situ population of <Emphasis Type="Italic">Eurycorymbus cavaleriei</Emphasis> (Sapindaceae) as revealed by categorical paternity analysis

Understanding the patterns of contemporary, pollen-mediated gene flow is of great importance for designing appropriate conservation strategies. In this study, ten novel polymorphic microsatellite loci were isolated for the rare dioecious tree, Eurycorymbus cavaleriei, and the patterns of pollen dispersal were investigated in an ex situ conserved population. A combination of microsatellite markers with high-collective exclusion power (0.932) was used to assign paternity to 240 seeds collected from eight maternal trees. The average effective pollen dispersal distance (δ) was 292.6 m and the frequency distribution of pollen movement suggested extensive pollen movement in the population. The effective pollen donors per maternal tree (N _ep) ranged from 5 to 10, and the most isolated maternal trees were observed with the largest number of N _ep = 10. Although a trend of near-neighbor mating was found in seven of eight maternal trees, no significant correlations were detected between the average effective pollen dispersal distance (δ) and the geographic distances (d1 and d2) between maternal and male trees. The increased average effective distance of pollen dispersal and number of N _ep for isolated maternal trees might be a compound consequence of low density and long-distance flight of pollinators of this species. The conservation implications of these results are discussed.     

Fine‐scale genetic structure and flowering output of the seagrass Enhalus acoroides undergoing disturbance

Seagrass are under great stress in the tropical coast of Asia, where Enhalus acoroides is frequently the dominant species with a large food web. Here, we investigate the question of the fine‐scale genetic structure of this ecologically important foundation species, subject to severe anthropogenic disturbance in China. The genetic structure will illuminate potential mechanisms for population dynamics and sustainability, which are critical for preservation of biodiversity and for decision‐making in management and restoration. We evaluated the fine‐scale spatial genetic structure (SGS) and flowering output of E. acoroides, and indirectly estimated the relative importance of sexual versus asexual reproduction for population persistence using spatial autocorrelation analysis. Results reveal high clonal diversity for this species, as predicted from its high sexual reproduction output. The stronger Sp statistic at the ramet‐level compared with genet‐level indicates that clonality increases the SGS pattern for E. acoroides. Significant SGS at the genet‐level may be explained by the aggregated dispersal of seed/pollen cohorts. The estimated gene dispersal variance suggests that dispersal mediated by sexual reproduction is more important than clonal growth in this study area. The ongoing anthropogenic disturbance will negatively affect the mating pattern and the SGS patterns in the future due to massive death of shoots, and less frequency of sexual reproduction.     

Inferring demographic processes from the genetic structure of a metapopulation of <Emphasis Type="Italic">Boltonia decurrens</Emphasis>(Asteraceae)

Boltonia decurrens(Asteraceae), a federally listed, threatened floodplain species, requires regular flooding for suitable habitat and seed dispersal. Flood suppression and habitat destruction have resulted in fewer than 25 populations remaining throughout its 400 km range. Because individual populations are widely interspaced (>10 km) and subject to frequent extinction and colonization, seed dispersal along the river, not pollen flow, is likely the primary determinant of population genetic structure. We used neutral genetic markers (isozymes) assayed for fourteen populations to determine which demographic processes contribute to the genetic structure of B. decurrens. Significant genetic differentiation was detected among populations (F _ST=0.098, P< 0.05) but not among regions (F _RT=0.013, P> 0.05), suggesting that long-distance dispersal events occur and involve seed from a small number of populations. Correspondingly, we found no evidence of isolation by distance, and admixture analyses indicate that colonization events involve seed from 3 to 5 source populations. Individual populations exhibited high levels of fixation (mean F _IS=0.192, P< 0.05), yet mean population outcrossing rates were high (t _m=0.87–0.95) and spatial autocorrelation analyses revealed no fine-scale within population structure, indicating that inbreeding alone cannot explain the observed fixation. Rather, genetic bottlenecks, detected for 12 of 14 populations, and admixture at population founding may be important sources of fixation. These observations are consistent with a metapopulation model and confirm the importance of regular flooding events, capable of producing suitable habitat and dispersing seed long distances, to the long-term persistence of B. decurrens.     

Population genetic structure of striped mullet, Mugil cephalus, along the coast of China, inferred by AFLP fingerprinting

The striped mullet, Mugil cephalus, is an economically important species for both aquaculture and commercial fisheries in China. In this study, the amplified fragment length polymorphism (AFLP) technique was employed to analyze population genetic diversity and genetic distance between different populations with the aim of elucidating the population structure and gene flow of M. cephalus along the coast of China. A total of 230 fragments with 150–500 bp were identified from 118 individuals by five AFLP primer combinations. The polymorphic loci within populations varied from 46.52% to 64.78%, with an average of 53.91%, and the average heterozygosity from 0.1829 to 0.2282, with an average of 0.2074. The UPGMA phenograms of 118 individuals were constructed based on Dice similarity coefficients and four clusters were recognized. AMOVA analysis revealed that 60.7% of genetic variations were within populations and 39.3% between populations. The estimated genetic distance (φ_ST) value over all polymorphic loci across the six populations was 0.393 (p < 0.0010), indicating a strong population structuring. The pairwise φ_ST value ranged from 0.1112 to 0.5358, with an average of 0.3693. The population pairwise gene flows (average N_m = 0.73) are low. In addition, the result of the Mantel test showed that there was a significant correlation between geographic and genetic distances (r = 0.5434, p = 0.0050). It was speculated that there exist at least four distinct geographic populational subdivisions of M. cephalus along the Chinese coast. This research has provided new molecular data which will aid our understanding of the genetic structure of this species.     

Limited pollen-mediated dispersal and partial self-incompatibility in the rare ironstone endemic <Emphasis Type="Italic">Tetratheca paynterae</Emphasis> subsp. <Emphasis Type="Italic">paynterae</Emphasis> increase the risks associated with habitat loss

Patterns of mating and dispersal are key factors affecting the dynamics, viability and evolution of plant populations. Changes in mating system parameters can provide evidence of anthropogenic impacts on populations of rare plants. Tetratheca paynterae subsp. paynterae is a critically endangered perennial shrub confined to a single ironstone range in Western Australia. Mining of the range removed 25% of plants in 2004 and further plants may be removed if the viability of the remaining populations is not compromised. To provide baseline genetic data for monitoring mining impacts, we characterised the mating system and pollen dispersal over two seasons in T. paynterae subsp. paynterae and compared mating system parameters with two other ironstone endemics, T. paynterae subsp. cremnobata and T. aphylla subsp. aphylla that were not impacted by mining. T. paynterae subsp. paynterae was the only taxon showing evidence of inbreeding (t _m = 0.89), although hand pollination revealed pre-zygotic self-incompatibility limits the production of seed from self-pollen. In a year of lower fruit set (2005), the estimate of correlated paternity increased from 20 to 35%. Direct estimates of realised pollen dispersal, made by paternity assignment in two small populations where all adult plants were genotyped, revealed a leptokurtic distribution with 30% of pollen dispersed less than 3 m and 90% less than 15 m. Restricted pollen dispersal maintains the strong genetic structuring of the adult populations in succeeding generations. As a consequence of preferential outcrossing, any reduction in effective population size, flowering plant density and/or the abundance and activity of pollinators may impact negatively on population viability through reduced seed set, increased inbreeding and increased correlated paternity.     

Genetic variation and genotypic diversity in Epipactis helleborine populations from NE Poland

Enzyme electrophoreses were used to estimate genetic variation in five populations of Epipactis helleborine from two National Parks (Biebrza and Wigry) in northeast Poland. It has been proved that populations from these two regions differed in genetic structure, with the populations belonging to the Biebrza group having a higher level of genetic variation than those from Wigry. The number of polymorphic loci (P) ranged from 18.2% to 40.9% and the mean number of alleles per polymorphic locus (Ap) from 2.25 to 2.80. Although the observed heterozygosity (H_o) was lower than the expected one (H_e) in each population, the values of H_o and H_e were 2–3 times lower in the populations from Wigry than in those from Biebrza. Excluding the LUK population with the smallest genotypic diversity, the majority of 345 distinct multilocus genotypes occurred only once, sporadically 2–4 times in each population and their frequency ranged from 0.2% to 3.7%. Moreover, factors shaping genetic structure of E. helleborine and their intensity varied in the populations studied. Reproduction from seeds seems to influence greatly the genetic variation of the populations from the Biebrza National Park, while an assortative mating between related individuals or population size appears to be more important in the case of the populations from the Wigry National Park.     

Fine-scale genetic structure of a long-lived reptile reflects recent habitat modification

Anthropogenic habitat fragmentation — ubiquitous in modern ecosystems — has strong impacts on gene flow and genetic population structure. Reptiles may be particularly susceptible to the effects of fragmentation because of their extreme sensitivity to environmental conditions and limited dispersal. We investigate fine-scale spatial genetic structure, individual relatedness, and sex-biased dispersal in a large population of a long-lived reptile (tuatara, Sphenodon punctatus) on a recently fragmented island. We genotyped individuals from remnant forest, regenerating forest, and grassland pasture sites at seven microsatellite loci and found significant genetic structuring (R_ST = 0.012) across small distances (< 500 m). Isolation by distance was not evident, but rather, genetic distance was weakly correlated with habitat similarity. Only individuals in forest fragments were correctly assignable to their site of origin, and individual pairwise relatedness in one fragment was significantly higher than expected. We did not detect sex-biased dispersal, but natural dispersal patterns may be confounded by fragmentation. Assignment tests showed that reforestation appears to have provided refuges for tuatara from disturbed areas. Our results suggest that fine-scale genetic structuring is driven by recent habitat modification and compounded by the sedentary lifestyle of these long-lived reptiles. Extreme longevity, large population size, simple social structure and random dispersal are not strong enough to counteract the genetic structure caused by a sedentary lifestyle. We suspect that fine-scale spatial genetic structuring could occur in any sedentary species with limited dispersal, making them more susceptible to the effects of fragmentation.     

Social constraint and an absence of sex‐biased dispersal drive fine‐scale genetic structure in white‐winged choughs

This study used eight polymorphic microsatellite loci to examine the relative effects of social organization and dispersal on fine‐scale genetic structure in an obligately cooperative breeding bird, the white‐winged chough (Corcorax melanorhamphos). Using both individual‐level and population‐level analyses, it was found that the majority of chough groups consisted of close relatives and there was significant differentiation among groups (F_ST = 0.124). However, spatial autocorrelation analysis revealed strong spatial genetic structure among groups up to 2 km apart, indicating above average relatedness among neighbours. Multiple analyses showed a unique lack of sex‐biased dispersal. As such, choughs may offer a model species for the study of the evolution of sex‐biased dispersal in cooperatively breeding birds. These findings suggest that genetic structure in white‐winged choughs reflects the interplay between social barriers to dispersal resulting in large family groups that can remain stable over long periods of times, and short dispersal distances which lead to above average relatedness among neighbouring groups.     

Sex‐biased dispersal and high levels of gene flow among local populations in the argentine boa constrictor,Boa constrictor occidentalis

Abstract The knowledge of dispersal is essential to understand the ecology of any species, since population dynamics, spatial distribution and genetic structure are closely tied to patterns of movement. In this paper we estimate dispersal patterns in natural populations of the endangered snake Boa constrictor occidentalis (Serpentes, Boidae), using allozymes as genetic markers. Blood samples were obtained from a total of 120 adult individuals of nine localities from two areas, Sobremonte and Pocho, in Argentina. Only four out of a total of 24 loci were polymorphic: 6‐Pgdh‐1, Cat‐1, Ldh and Hp. The values of expected and observed mean heterozygosities, the percentage of polymorphic loci and mean number of alleles per locus for each population confirm the low levels of genetic variability in this snake. F_ST and N_em mean values were 0.0089 and 46.1 for Sobremonte and 0.0379 and 7.46 for Pocho, indicating important levels of gene flow. A comparison of F_ST between genders in both areas suggests a male‐biased dispersal, which could be explained by the characteristics of the mating system: males carry out an active mate search of receptive females, and philopatry could be selected in females due to the benefits of the familiarity with the natal area in the use of local resources.     

The physiology of spore-negative and spore-positive nodules ofMyrica gale

The physiology of spore-negative and spore-positive root nodules was investigated inMyrica gale L. grown in water culture in a growth chamber. Spore(–) nodules were induced withFrankia cultures and spore(+) nodules with crushed nodules. Gas exchange was measured in a flow-through system.The time course of acetylene reduction following addition of acetylene was essentially the same in both spore(–) and spore(+) nodules with a stable maximum between 2 and 4 minutes followed by a steep decline to a minimum (37% of the maximum) between 9 and 30 minutes depending on the plant. The minimum was followed by a partial recovery. Nodule CO₂ evolution showed a similar pattern but the minimum rate (83% of the maximum) was not nearly as low.Plants nodulated with one spore(–) and one spore(+) strain were compared at 6, 8 and 10 weeks after inoculation. At 6 weeks the spore(–) plants had 52% greater specific nitrogenase activity and 46% more biomass than the spore(+) plants. At 8 and 10 weeks, however, the differences between plants with spore(–) and spore(+) nodules became smaller.Plants nodulated with 4 spore(–) and 5 spore(+) strains were compared at 8 weeks after inoculation. Collectively the spore(–) plants exhibited a 32% greater specific nitrogenase activity, a 15% lower energy cost of nitrogenase activity (CO₂/C₂H₄), and invested 31% less biomass in nodules than the spore(+) plants. The spore(–) plants also produced 16% more biomass indicating that spore(–) strains are generally more desirable than spore(+) strains. However, two spore(+) strains were as effective as the spore(–) strains.     

Long‐term consistency in spatial patterns of primate seed dispersal

Seed dispersal is a key ecological process in tropical forests, with effects on various levels ranging from plant reproductive success to the carbon storage potential of tropical rainforests. On a local and landscape scale, spatial patterns of seed dispersal create the template for the recruitment process and thus influence the population dynamics of plant species. The strength of this influence will depend on the long‐term consistency of spatial patterns of seed dispersal. We examined the long‐term consistency of spatial patterns of seed dispersal with spatially explicit data on seed dispersal by two neotropical primate species, Leontocebus nigrifrons and Saguinus mystax (Callitrichidae), collected during four independent studies between 1994 and 2013. Using distributions of dispersal probability over distances independent of plant species, cumulative dispersal distances, and kernel density estimates, we show that spatial patterns of seed dispersal are highly consistent over time. For a specific plant species, the legume Parkia panurensis, the convergence of cumulative distributions at a distance of 300 m, and the high probability of dispersal within 100 m from source trees coincide with the dimension of the spatial–genetic structure on the embryo/juvenile (300 m) and adult stage (100 m), respectively, of this plant species. Our results are the first demonstration of long‐term consistency of spatial patterns of seed dispersal created by tropical frugivores. Such consistency may translate into idiosyncratic patterns of regeneration.