Dry-washes determine gene flow and genetic diversity in a common desert shrub

Context

In deserts, many plant species exhibit a patchy spatial distribution within a harsh habitat matrix, where the likelihood of propagule dispersal among patches is uncertain, but may be promoted by landscape corridors or dispersal vectors.

Objectives

We examine the connectivity of a representative desert plant species (Acacia (Senegalia) greggii), and the ability of three major factors (animal dispersal agents, water flow along dry-washes, and climate) to facilitate dispersal within four watersheds in the Mojave National Preserve.

Methods

We genotyped 323 individuals sampled across 22 one-hectare sites using ten nuclear microsatellite markers.

Results

A hierarchical AMOVA revealed no significant differentiation among watersheds (F _RT = 0.00, P > 0.10), and very little genetic structure among all sites (F _ST = 0.03, P < 0.001), indicating regional connectivity. Mantel tests indicated distance along dry-washes best explained genetic distance between sites (r = 0.47, P < 0.05) when compared to Euclidean distance (P > 0.05), a distance measure based on rodent dispersal (P > 0.05), and a distance measure avoiding inhospitable climate (P > 0.05). An AIC comparison of generalized linear models found that within site genetic diversity (H _E and allelic richness) and average relatedness were best explained by slope (which increases seed dispersal potential via water flow) and area of the upstream watershed (which determines the number of potential seed donors), rather than plant density or habitat suitability.

Conclusions

Together, these findings indicate that dry-washes are key landscape features that enhance dispersal and regional connectivity in this patchy desert plant.

     

The Genus <Emphasis Type="Italic">Fragaria </Emphasis>in Croatia

Only three native species of genus Fragaria (F. moschata, F. vesca and F. viridis) are recorded in three regions of Croatia. These species as well as many of their hybrids, are, or once were, cultivated for their edible fruits. The majority of cultivated strawberries in Europe belong to garden strawberries F. x ananassa (hybrids of F. chiloensis and F. virginiana). The most expanded wild strawberry species in Croatia is a woodland strawberry (F. vesca) whose berries are gathered seasonally as wild edible fruits. They often contain higher amount of nutrients and bioactive compounds in comparison to cultivated varieties. The research on the genus Fragaria species distribution in Croatia has not been carried out, and so is the case with many others wild growing fruit species in Croatia. By summing up a number of individual citations and observations, it is possible to get a perspective regarding the current state of their distribution.     

<Emphasis Type="Italic">Dactylonectria torresensis</Emphasis> as the Main Component of the Black Root Rot Complex of Strawberries and Raspberries in Northern Germany

In a long-term survey of black root rot of strawberries and raspberries in Northern Germany in 2007–2014, fungi with and without Cylindrocarpon-like anamorphs were isolated as potential pathogens. Dactylonectria torresensis was the most common species, being isolated from 18% of strawberry roots obtained from nursery plants and 37% of roots from production fields, as well as 21% and 29% (respectively) of raspberry roots. Less frequently isolated fungi with Cylindrocarpon-like anamorphs included Ilyonectria crassa, Ilyonectria sp. 2, I. pseudodestructans, I. robusta, C. obtusisporium and Ilyonectria sp. 1. Severe disease symptoms were reproduced by artificial inoculation of strawberries with D. torresensis, I. crassa and Ilyonectria sp. 2, milder symptoms with C. obtusisporium. A wide range of other root-pathogenic fungi such as Fusarium oxysporum, Verticillium dahliae, Ceratobasidium fragariae, Gnomoniopsis fructicola, Hainesia lythri, and species of Cadophora, Leptodontidium, Pythium, Phytophthora, Plectosporella, Pestalotiopsis and Truncatella were either isolated only sporadically or were not associated with black root rot symptoms, suggesting that they did not play any major role in this disease in Northern Germany. Visible disease symptoms and high frequencies of D. torresensis isolations in many batches of nursery plants indicated that these may comprise a major source of contamination of production fields. The previously unrecognised prominence of D. torresensis resolves a long-standing puzzle concerning the cause of the ongoing black root rot epidemic in Northern German strawberry and raspberry production.     

Landscape genetics of the foundational salt marsh plant species black needlerush (<Emphasis Type="Italic">Juncus roemerianus</Emphasis> Scheele) across the northeastern Gulf of Mexico

Context

Common species important for ecosystem restoration stand to lose as much genetic diversity from anthropogenic habitat fragmentation and climate change as rare species, but are rarely studied. Salt marshes, valuable ecosystems in widespread decline due to human development, are dominated by the foundational plant species black needlerush (Juncus roemerianus Scheele) in the northeastern Gulf of Mexico.

Objectives

We assessed genetic patterns in J. roemerianus by measuring genetic and genotypic diversity, and characterizing population structure. We examined population connectivity by delineating possible dispersal corridors, and identified landscape factors influencing population connectivity.

Methods

A panel of 19 microsatellite markers was used to genotype 576 samples from ten sites across the northeastern Gulf of Mexico from the Grand Bay National Estuarine Research Reserve (NERR) to the Apalachicola NERR. Genetic distances (F_ST and D_ch) were used in a least cost transect analysis (LCTA) within a hierarchical model selection framework.

Results

Genetic and genotypic diversity results were higher than expected based on life history literature, and samples structured into two large, admixed genetic clusters across the study area, indicating sexual reproduction may not be as rare as predicted in this clonal macrophyte. Digitized coastal transects buffered by 500 m may represent possible dispersal corridors, and developed land may significantly impede population connectivity in J. roemerianus.

Conclusions

Results have important implications for coastal restoration and management that seek to preserve adaptive potential by sustaining natural levels of genetic diversity and conserving population connectivity. Our methodology could be applied to other common, widespread and understudied species.

     

Are landscapes more than the sum of their patches?

Context

The species–area relationship (SAR) is the most ubiquitous scaling relationship in ecology, yet we still do not know how different aspects of scale affect this relationship. Scale is defined by grain, extent, and focus. Focus here pertains to whether patches or landscapes are used to derive SARs.

Objective

To explore whether altering the focal scale influences the resulting SAR. If the SAR is scale-invariant, patch-based and landscape-based SARs should be congruent.

Methods

I fit a power-law function (S = cA ^z) to arthropod data obtained from an experimental landscape system, in which habitat amount and configuration (clumped vs. fragmented) of red clover (Trifolium pratense) varied among plots (256 m²). The scaling coefficient (z) was compared among patch-based and landscape-based SARs for congruence.

Results

Patches gained species at a faster rate than landscapes (z = 0.37 vs. 0.26, respectively), producing domains of incongruity in the SAR. Landscape richness (S _L) was greater than patch richness (S _P) below 30 % habitat, but S _P > S _L above 60 % habitat. Landscape configuration contributed to this incongruity below 30 % habitat (fragmented S _L > clumped S _L), but landscape context (whether the largest patch was embedded in a fragmented or clumped landscape) was important above 60 % habitat for understanding the SAR in this domain.

Conclusions

Landscape configuration exerts both direct (<30 % habitat) and indirect (>60 % habitat) effects on the SAR. Because patch-based and landscape-based SARs may not be congruent, we should exercise care when extrapolating from patches to landscapes to make inferences about the effects of habitat loss and fragmentation on species richness.

     

Contiguity of landscape features pose barriers to gene flow among American marten (<Emphasis Type="Italic">Martes americana</Emphasis>) genetic clusters in the Upper Peninsula of Michigan

Context

Barriers to dispersal influence the ability of individuals to expand into new areas and can ultimately define success of reintroduction programs. American marten (Martes americana) were reintroduced to the Upper Peninsula of Michigan, USA, from multiple, genetically differentiated source populations from 1955 to 1992. Previous research found multiple genetic clusters near release sites with little admixing, suggesting barriers to dispersal exist.

Objectives

We sought to identify whether the contact zones between genetic clusters coincided with landscape features hypothesized to influence M. americana dispersal. We also investigated whether the degree of landscape contiguity within each genetic cluster differed among clusters.

Methods

We mapped cluster boundaries in M. americana genetic assignment probabilities and used correlation length as a measure of landscape contiguity between genetic clusters. We then evaluated the effects of land cover and roads on spatial genetic structure using a spatial autoregressive model.

Results

We found that gene flow was facilitated by contiguous coniferous forest and low incidence of roads. However, the strength of those relationships varied by genetic cluster. Contact zones among some genetic clusters spatially coincided with areas of high road and low conifer contiguity, compared to within-clusters.

Conclusions

In contrast to landscape genetic analyses focused on identifying barriers to gene flow, we incorporated methods that are relatively novel in landscape genetics to quantify how landscape contiguity influences spatial genetic structure. Using this method we were able to identify landscape barriers to dispersal at the genetic cluster boundaries for a reintroduced species distributed continuously across the landscape.

     

Disentangling the relative effect of light pollution,impervious surfaces and intensive agriculture on bat activity with a national-scale monitoring program

Context

Light pollution is a global change affecting a major proportion of global land surface. Although the impacts of Artificial Light At Night (ALAN) have been documented locally for many taxa, the extent of effect of ALAN at a landscape scale on biodiversity is unknown.

Objectives

We characterized the landscape-scale impacts of ALAN on 4 insectivorous bat species Pipistrellus pipistrellus, Pipistrellus kuhlii, Eptesicus serotinus, Nyctalus leisleri, and compared the extent of their effects to other major land-use pressures.

Methods

We used a French national-scale monitoring program recording bat activity among 2-km car transect surveys, and extracted landscape characteristics around transects with satellite and land cover layers. For each species, we performed multi-model averaging at 4 landscape scales (from 200 to 1000 m buffers around transects) to compare the relative effects of the average radiance, the proportion of impervious surface and the proportion of intensive agriculture.

Results

For all species, ALAN had a stronger negative effect than impervious surface at the 4 landscape scales tested. This effect was weaker than the effect of intensive agriculture. The negative effect of ALAN was significant for P. pipistrellus, P. kuhlii and E. serotinus, but not for N. leisleri. The effect of impervious surface varied among species while intensive agriculture had a significant negative effect on the 4 species.

Conclusion

Our results highlight the need to consider the impacts of ALAN on biodiversity in land-use planning and suggest that using only impervious surface as a proxy for urbanization may lead to underestimated impacts on biodiversity.

     

A Field Survey of Promising Mulberry (M<Emphasis Type="Italic">orus spp</Emphasis>.) Genotypes from Turkey

In this study the mulberry population in the Mediterranean and Eastern Anatolia Turkey was examined with regard to fruit properties. The research material consisted of uncultivated mulberry (Morus spp.) trees. Thirty five mulberry genotypes for table, 6 genotypes for fruit juice, 11 genotypes for syrup (pekmez) and 9 genotypes for drying, were selected, 32 of which belonged to Morus alba, 12 to Morus rubra and 8 genotypes to Morus nigra. Continued and more detailed selection studies with this population of genotypes are necessary to provide material that is suitable for future breeding efforts. It may also be possible to select some of this native material that has sufficient commercial value to justify its release to growers.     

A network model framework for prioritizing wetland conservation in the Great Plains

Context

Playa wetlands are the primary habitat for numerous wetland-dependent species in the Southern Great Plains of North America. Plant and wildlife populations that inhabit these wetlands are reciprocally linked through the dispersal of individuals, propagules and ultimately genes among local populations.

Objective

To develop and implement a framework using network models for conceptualizing, representing and analyzing potential biological flows among 48,981 spatially discrete playa wetlands in the Southern Great Plains.

Methods

We examined changes in connectivity patterns and assessed the relative importance of wetlands to maintaining these patterns by targeting wetlands for removal based on network centrality metrics weighted by estimates of habitat quality and probability of inundation.

Results

We identified several distinct, broad-scale sub networks and phase transitions among playa wetlands in the Southern Plains. In particular, for organisms that can disperse >2 km a dense and expansive wetland sub network emerges in the Southern High Plains. This network was characterized by localized, densely connected wetland clusters at link distances (h) >2 km but <5 km and was most sensitive to changes in wetland availability (p) and configuration when h = 4 km, and p = 0.2–0.4. It transitioned to a single, large connected wetland system at broader spatial scales even when the proportion of inundated wetland was relatively low (p = 0.2).

Conclusions

Our findings suggest that redundancy in the potential for broad and fine-scale movements insulates this system from damage and facilitates system-wide connectivity among populations with different dispersal capacities.

     

Connectivity analysis as a tool for assessing restoration success

Context

Methods for measuring restoration success that include functional connectivity between species’ populations are rare in landscape ecology and restoration practices. We developed an approach that analyzes connectivity between populations of target species and their dispersal probabilities to assess restoration success based on easily accessible input data. Applying this method to landscape development scenarios can help optimize restoration planning.

Objectives

We developed an assessment for restoration success and restoration planning based on functional connectivity between species’ populations and spatially explicit scenarios. The method was used in a case study to test its applicability.

Methods

Based on data on available habitat, species’ occurrence and dispersal ranges, connectivity metrics and dispersal probabilities for target species are calculated using the software Conefor Sensinode. The metrics are calculated for scenarios that reflect possible changes in the landscape to provide a basis for future restoration planning. We applied this approach to floodplain meadows along the Upper Rhine for four plant species and three future scenarios.

Results

In the case study, habitats of the target species were poorly connected. Peucedanum officinale and Sanguisorba officinalis were more successful in recolonizing new habitats than Iris spuria and Serratula tinctoria. The scenarios showed that restoration of species-rich grassland was beneficial for dispersal of the target species. As expected in the agriculturally dominated study area, restoration of former arable land significantly increased dispersal probabilities.

Conclusions

In the case study, the developed approach was easily applicable and provided reasonable results. Its implementation will be helpful in decision-making for future restoration planning.

     

Assessment of Genetic Variability in Pistachio (<Emphasis Type="Italic">Pistacia vera</Emphasis> L.) with Nuclear SSR Molecular Markers

Pistachio (Pistacia vera L.) is considered to be the most widely cultivated species in the genus Pistacia and regarded as the most probable ancestral species within the genus. As one of the oldest nut crops in human history, pistachio nuts have a high nutritional value and are commercially important. In the present study, the genetic variation of pistachio genotypes was investigated by nuclear SSR markers. The transferability of the SSR markers was high across genotypes, thus, flanking regions of the SSRs are conserved in the studied genotypes. High level of polymorphism was detected among the studied genotypes. The seven SSR primer pairs generated a total of 18 alleles that 13 of them were polymorphic among the genotypes. The range of the polymorphic alleles was 1 (for Ptms9, Ptms40, Ptms41, and Ptms42) to 5 (for Ptms7 locus) with an average of 2.57. The amplified allele sizes ranged from 120 to 250?bp. Pair-wise genetic similarity coefficients varied from 0.20 to 0.75. The UPGMA dendrogram differentiated the genotypes into two major clusters. The present results may be used for the conservation, core collection and future breeding of the pistachio.     

The Potential of Caprifig Genotypes for Sheltering <Emphasis Type="Italic">Blastophaga psenes</Emphasis> L. for Caprification of Edible Figs

Caprifig (Ficus carica L.) as pollen sources, play a major role in edible fig caprification by Blastophaga psenes L. The present study was carried out to evaluate the potential of three caprifig genotypes (Poozdombali, Kouhi and Kouhaki) for the shelter of B. psenes wasp in Estahban region, Fars province, Iran. Summer (profichi) crop fruits per genotype were harvested in full maturity period and evaluated for five times for the shelter of B. psenes wasp. Significant differences among caprifig genotypes were found for B. psenes number for the three times carried out (0, 21 and 28 days), but they did not show significant differences for two times (7 and 14 days). At day of harvesting, Poozdombali showed the highest B. psenes wasp number (341.33) and Kouhaki had the lowest (200.00) and they showed significant differences for this character in this time. Also, seven days after harvesting, Poozdombali showed the highest wasp number (106.67) and Kouhi and Kouhaki had the lowest (104.33), but not significant difference. Number of B. psenes at the day of harvesting was the highest for all of the genotypes and at 28 days after harvesting was the lowest. Cluster analysis identified two major clusters with several sub-clusters. Caprifig trees with having high B. psenes number are essential for a suitable caprification. Thus, Poozdombali genotype with the highest B. psenes number, is suitable in this important trait to be used for edible figs caprification.     

Surface metrics: scaling relationships and downscaling behavior

Context

Considerable research has examined scale effects for patch-based metrics with the ultimate goal of predicting values at finer resolutions (i.e., downscaling), but results have been inconsistent. Surface metrics have been suggested as an alternative to patch-based metrics, although far less is known about their scaling relationships and downscaling potential. If successful, downscaling would enable integration of disparate datasets and comparison of landscapes using different resolution datasets.

Objectives

(1) Determine how surface metrics scale as resolution changes and how consistent those scaling relationships are across landscapes. (2) Test whether these scaling relationships can be accurately downscaled to predict metric values for finer resolutions.

Methods

Various scaling functions were fit to 16 surface metrics computed for multiple resolutions for a set of landscapes. Best-fitting functions were then extrapolated to test downscaling behavior (i.e., predict metric value for a finer resolution) for an independent set of validation landscapes. Relative error was assessed between the predicted and true values to determine downscaling robustness.

Results

Seven surface metrics (Sa, Sq, S10z, Sdq, Sds, Sdr, Srwi) fit consistently well (R² > 0.99) with a 3rd order polynomial or power law. Of those, the scaling functions for Sa, Sq, and S10z were able to predict metric values at a finer resolution within 5 %. Three metrics, (Ssk, Sku, Sfd) were also notable in terms of fit and downscaling.

Conclusions

Many metrics exhibit consistent scaling relations across resolution, and several are able to accurately predict values at finer resolutions. However, prediction accuracy is likely related to the amount of information lost during aggregation.

     

Anther culture in rice proportionally rescues microspores according to gametophytic gene effect and enhances genetic study of hybrid sterility

Background

To investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima). Male gametes of these hybrids display complete sterility owing to a dozen of hybrid sterility loci, termed HS loci, but this complicated genetic system remains poorly understood.

Results

Microspores from these interspecific hybrids form sterile pollen but are viable at the immature stage. Application of the anther culture (AC) method caused these immature microspores to induce callus. The segregation distortion of 11 among 13 known HS loci was assessed in the callus population. Using many individual calli, fine mapping of the HS loci was attempted based on heterozygotes produced from chromosome segment substitution lines (CSSLs). Transmission ratio distortion (TRD) from microspores was detected at 6 of 11 HS loci in the callus population. The fine mapping of S₁ and S₁₉ loci using CSSLs revealed precise distances of markers from the positions of HS loci exhibiting excessive TRD.

Conclusions

We demonstrated that AC to generate callus populations derived from immature microspores is a useful methodology for genetic study. The callus population facilitated detection of TRD at multiple HS loci and dramatically shortened the process for mapping hybrid sterility genes.

     

In situ hybridization for the detection of rust fungi in paraffin embedded plant tissue sections

Background

Rust fungi are obligate pathogens with multiple life stages often including different spore types and multiple plant hosts. While individual rust pathogens are often associated with specific plants, a wide range of plant species are infected with rust fungi. To study the interactions between these important pathogenic fungi and their host plants, one must be able to differentiate fungal tissue from plant tissue. This can be accomplished using the In situ hybridization (ISH) protocol described here.

Results

To validate reproducibility using the ISH protocol, samples of Chrysanthemum × morifolium infected with Puccinia horiana, Gladiolus × hortulanus infected with Uromyces transversalis and Glycine max infected with Phakopsora pachyrhizi were tested alongside uninfected leaf tissue samples. The results of these tests show that this technique clearly distinguishes between rust pathogens and their respective host plant tissues.

Conclusions

This ISH protocol is applicable to rust fungi and potentially other plant pathogenic fungi as well. It has been shown here that this protocol can be applied to pathogens from different genera of rust fungi with no background staining of plant tissue. We encourage the use of this protocol for the study of plant pathogenic fungi in paraffin embedded sections of host plant tissue.

     

Exploring dispersal barriers using landscape genetic resistance modelling in scarlet macaws of the Peruvian Amazon

Context

Dispersal is essential for species persistence and landscape genetic studies are valuable tools for identifying potential barriers to dispersal. Macaws have been studied for decades in their natural habitat, but we still have no knowledge of how natural landscape features influence their dispersal.

Objectives

We tested for correlations between landscape resistance models and the current population genetic structure of macaws in continuous rainforest to explore natural barriers to their dispersal.

Methods

We studied scarlet macaws (Ara macao) over a 13,000 km² area of continuous primary Amazon rainforest in south-eastern Peru. Using remote sensing imagery from the Carnegie Airborne Observatory, we constructed landscape resistance surfaces in CIRCUITSCAPE based on elevation, canopy height and above-ground carbon distribution. We then used individual- and population-level genetic analyses to examine which landscape features influenced gene flow (genetic distance between individuals and populations).

Results

Across the lowland rainforest we found limited population genetic differentiation. However, a population from an intermountain valley of the Andes (Candamo) showed detectable genetic differentiation from two other populations (Tambopata) located 20–60 km away (F _ST = 0.008, P = 0.001–0.003). Landscape resistance models revealed that genetic distance between individuals was significantly positively related to elevation.

Conclusions

Our landscape resistance analysis suggests that mountain ridges between Candamo and Tambopata may limit gene flow in scarlet macaws. These results serve as baseline data for continued landscape studies of parrots, and will be useful for understanding the impacts of anthropogenic dispersal barriers in the future.

     

How landscape,pollen intake and pollen quality affect colony growth in <Emphasis Type="Italic">Bombus terrestris</Emphasis>

Context

Abundance and diversity of bumblebees have been declining over the past decades. To successfully conserve bumblebee populations, we need to understand how landscape characteristics affect the quantity and quality of floral resources collected by colonies and subsequently colony performance.

Objectives

We therefore investigated how amount and composition of pollen collected by buff-tailed bumblebee Bombus terrestris colonies was affected by the surrounding landscape (i.e. the proportion of forest, urban, semi-natural habitats) and how they were related to colony growth.

Methods

Thirty B. terrestris colonies were placed at grassland sites differing in surrounding landscape. Colonies were established in spring when availability of flowering plants was highest, and their weight gain was monitored for 1 month. We additionally recorded the quantity and compared plant taxonomic composition and nutritional quality (i.e. amino acid composition) of pollen stored.

Results

Bumblebee colonies varied little in the pollen spectra collected despite differences in surrounding landscape composition. They collected on average 80 % of pollen from woody plants, with 34 % belonging to the genus Acer. Early colony growth positively correlated with total amount of woody pollen and protein collected and decreased with increasing proportions of semi-natural habitats and total amino acid concentrations.

Conclusions

Our results suggest that woody plant species represent highly important pollen sources for the generalist forager B. terrestris early in the season. We further show that colony growth of B. terrestris is predominantly affected by the quantity, not quality, of forage, indicating that several abundant plant species flowering throughout the bumblebees’ foraging season may cover the colonies’ nutritional needs.

     

Determinants of spread in an urban landscape by an introduced lizard

Context

Urban landscapes are a mixture of built structures, human-altered vegetation, and remnant semi-natural areas. The spatial arrangement of abiotic and biotic conditions resulting from urbanization doubtless influences the establishment and spread of non-native species in a city.

Objectives

We investigated the effects of habitat structure, thermal microclimates, and species coexistence on the spread of a non-native lizard (Anolis cristatellus) in the Miami metropolitan area of South Florida (USA).

Methods

We used transect surveys to estimate lizard occurrence and abundance on trees and to measure vegetation characteristics, and we assessed forest cover and impervious surface using GIS. We sampled lizard body temperatures, habitat use, and relative abundance at multiple sites.

Results

At least one of five Anolis species occupied 79 % of the 1035 trees surveyed in primarily residential areas, and non-native A. cristatellus occupied 25 % of trees. Presence and abundance of A. cristatellus were strongly associated with forest patches, dense vegetation, and high canopy cover, which produced cooler microclimates suitable for this species. Presence of A. cristatellus was negatively associated with the ecologically similar non-native A. sagrei, resulting in reduced abundance and a shift in perch use of A. cristatellus.

Conclusions

The limited spread of A. cristatellus in Miami over 35 years is due to the patchy, low-density distribution of wooded habitat, which limits dispersal by diffusion. The presence of congeners may also limit spread. Open habitats—some parks, yards and roadsides—contain few if any A. cristatellus, and colonization of isolated forest habitat appears to depend on human-mediated dispersal.

     

The Determination of Nematode Tolerance and Seedling Performance of The Selected Almond (Prunus amygdalus L.) Genotypes in Isparta Province

In the present study, selected almond genotypes in Keciborlu/Isparta region by Y?ld?r?m (2007) based on late blooming and superior nut chacteristics were used to evaluate seedling growth performances and the reaction to root knot nematodes. Seeds were planted on perlite medium and stored 60 days at +4 ^°C in order to break seed dormancy. After germinating, seedlings were transferred to plastic pots to evaluate seedling growth characteristics and remaining seedlings were inoculated with Meloidogyne javanica and Meloidogyne incognita in order to asses resistance status of the selected seedlings. The highest germination percentage was obtained from Genotype 54 (96.1?%), the highest plant was observed from Genotype 9 (62.18 cm), the longest primary root was found from Genotype 54 (30.28 cm), the average secondary root lenght was highest in Genotype 9 (31.04 cm) and the widest root collar was observed in Genotype 33 (8.38 mm). Seedling stem diameter changed between 4.76 mm (Genoype 40) to 7.67 mm (Genotype 33). The lowest variation for stem widht was observed in Genotype 55 (0.58?%) while the lowest variation for seedling hight was found in Genotype 33 (0.50?%). Evaluated almond genotypes showed different reactions to studied nematode species, M. javanica and M. incognita. Resistant reactions of almond genotypes to nematode species were classified as susceptible, tolerant and resistant based on gal index values. Genotype 9 and 31 classified as tolerant to M. javanica while Genotype 54 classified as resistant to M. incognita.     

Effect of connectivity and habitat availability on the occurrence of the Chestnut-throated Huet-Huet (<Emphasis Type="Italic">Pteroptochos castaneus,</Emphasis> Rhinocryptidae) in fragmented landscapes of central Chile

Context

Although small isolated habitat patches may not be able to maintain a minimum viable population, small patches that are structurally isolated may be functionally connected if individuals can cross the gaps between them, in which case, their areas could be added to form a larger habitat patch, eventually surpassing the size threshold for holding a viable population.

Objectives

We studied whether models based on the size and isolation of habitat patches could be used to predict the distribution of the Chestnut-throated Huet-Huet (Pteroptochos castaneus) in fragmented landscapes of the coastal range of the Maule region, central Chile.

Methods

We selected seven 10,000-ha landscapes (8.4–70.7% forest cover). For each habitat patch we made 18 predictions of the presence of the species based on the combination of two thresholds: three critical patch sizes for maintaining a viable population (62.5, 125 and 250 ha) and six critical isolation distances between patches (0, 10, 50, 100, 150 and 200 m). We used playbacks in 59 sampling points to estimate the species’ presence/absence. We used logistic regressions to test whether the output of the patch-matrix models could explain part of the variation in the presence of Pteroptochos castaneus.

Results

The best predictions for the presence of P. castaneus were obtained with the most conservative scenarios (125–250 ha to 0–10 m), including a positive effect of the understory cover and a lack of effect of the forest type (native or exotic).

Conclusions

Our findings suggest that the long term persistence of P. castaneus may depend on the existence of large and/or very connected forest tracts.