Fire increases variance in genetic characteristics of Florida Sand Skink (Plestiodon reynoldsi) local populations

Fire is a complex event that maintains many ecological systems. The Florida Sand Skink (Plestiodon reynoldsi) is precinctive to Florida Scrub, a habitat that is maintained by infrequent fire. We characterize the effect of fire on genetic diversity and genetic differentiation at eight microsatellite loci in the Florida Sand Skink (n=470) collected from 30 replicate sites over three 'time since last fire' categories at the Archbold Biological Station. Long unburned sites had greater allelic richness and expected heterozygosity than either recently or intermediately burned sites. More recently, burned sites had greater standard deviations of allelic richness and private allelic richness. Expected heterozygosity positively correlated with 'time since fire' (r=0.36, P=0.05) and abundance (r=0.53, P=0.002). There was a significant spatial component to genetic differentiation, and results indicate individuals rarely disperse >1 km. Genetic differentiation was positively correlated with geographic distance in long unburned units (r=0.59, P=0.04), yet this relationship was disrupted by fire in recently (r=0.00, 1) and intermediately (r= -0.81, 0.05) burned areas. Simulations indicate that demographic changes to a local population could have generated the observed differences among 'time since fire' categories. Our findings indicate that infrequent fire may be beneficial to the Florida Sand Skink and that local populations begin to recover from changes attributable to the fire after 10 years. Too frequent fires may reduce genetic diversity because it may take multiple generations for local populations to recover.     

Congruent population structure inferred from dispersal behaviour and intensive genetic surveys of the threatened Florida scrub-jay (Aphelocoma coerulescens)

The delimitation of populations, defined as groups of individuals linked by gene flow, is possible by the analysis of genetic markers and also by spatial models based on dispersal probabilities across a landscape. We combined these two complimentary methods to define the spatial pattern of genetic structure among remaining populations of the threatened Florida scrub-jay, a species for which dispersal ability is unusually well-characterized. The range-wide population was intensively censused in the 1990s, and a metapopulation model defined population boundaries based on predicted dispersal-mediated demographic connectivity. We subjected genotypes from more than 1000 individual jays screened at 20 microsatellite loci to two Bayesian clustering methods. We describe a consensus method for identifying common features across many replicated clustering runs. Ten genetically differentiated groups exist across the present-day range of the Florida scrub-jay. These groups are largely consistent with the dispersal-defined metapopulations, which assume very limited dispersal ability. Some genetic groups comprise more than one metapopulation, likely because these genetically similar metapopulations were sundered only recently by habitat alteration. The combined reconstructions of population structure based on genetics and dispersal-mediated demographic connectivity provide a robust depiction of the current genetic and demographic organization of this species, reflecting past and present levels of dispersal among occupied habitat patches. The differentiation of populations into 10 genetic groups adds urgency to management efforts aimed at preserving what remains of genetic variation in this dwindling species, by maintaining viable populations of all genetically differentiated and geographically isolated populations.     

Genotypic diversity of a dominant C4 grass across a long-term fire frequency gradient

Aims and Methods Diversity-disturbance research has focused on community diversity, but disturbance frequency could impact diversity within species as well, with important consequences for community diversity and ecosystem function. We examined patterns of genetic diversity of a dominant grass species, Andropogon gerardii, in native North American tallgrass prairie sites located in eastern Kansas that have been subjected to a gradient of fire frequency treatments (burned every 1, 2, 4 or 20 years) since the 1970s. In addition, we were able to assess the relationships between genetic diversity of A. gerardii, species diversity and productivity across this range of fire frequencies.Important findings We found no significant relationships between genetic diversity of A. gerardii at the local scale (1 m 2 plot level) and disturbance frequency (burned 2 to 32 times over a 38-year period). However, at the site level (i.e. across all plots sampled within a site, ~100 m 2) there were differences in genotype richness and composition, as well as genomic dissimilarity among individuals of A. gerardii. Genotype richness was greatest for the site burned at an intermediate (4-year) frequency and lowest for the infrequently (20-year) burned site. In addition, genotypes found in the frequently burned sites were more similar from each other than expected by random chance than those found in the infrequently burned sites. Genotype composition of A. gerardii was not significantly different between the frequently burned sites (annual vs. 2 year) but did differ between frequently burned and infrequently burned sites (1 and 2 year vs. 4 and 20 year, etc.). Together, these results suggest site-level ecological sorting of genotypes in intact prairie across a broad gradient of disturbance frequencies, likely driven by alterations in environmental conditions. Frequent fire promotes the abundance of dominant grass species, reduces plant community diversity and impacts ecosystem processes such as productivity. Our study suggests that genetic diversity within dominant grass species also may be affected by disturbance frequency, which could have important implications for how species are able to respond to disturbance.     

Short-term impact of 1997/1998 ENSO-induced disturbance on abundance and genetic variation in a tropical butterfly

In order to assess the short-term impact of habitat loss after disturbance, we studied Arhopala epimuta (Lepidoptera: Lycaenidae) populations in 5 landscapes in Borneo that were differentially affected by the 1997/1998 El Ni?o Southern Oscillation-induced drought and fire. Sampling was conducted before (1997) and after (1998 and 2000) disturbance. This study combined demographic and genetic data inferred from the analysis of 5 microsatellite loci and mitochondrial DNA (mtDNA) control region sequences. Over all 5 landscapes, a total of 313 A. epimuta were sampled over the 3-year survey. Butterfly abundance varied greatly both spatially and temporally (within disturbed landscapes). After the disturbance, a 4-fold population expansion was observed in a small unburned isolate, whereas population extinction was observed in one of the severely burned areas. The analysis of mtDNA sequences in a subsample of 106 A. epimuta revealed no significant spatial or temporal genetic structure. The analysis of 5 microsatellite loci revealed high frequencies of null alleles. Genetic evidence of recent change in population size was found in all 3 unburned landscapes using microsatellites. Congruent to mtDNA, microsatellites failed to detect significant genetic structure according to sampling year or landscapes. Our results suggest that, for mobile species within recently fragmented habitat, habitat loss after disturbance may lead to local population extinction but may augment genetic diversity in remnant local populations because of increased gene flow.     

Demographic and genetic collapses in spatially structured populations: insights from a long‐term survey in wild fish metapopulations

Unraveling the relationship between demographic declines and genetic changes over time is of critical importance to predict the persistence of at‐risk populations and to propose efficient conservation plans. This is particularly relevant in spatially structured populations (i.e. metapopulations) in which the spatial arrangement of local populations can modulate both demographic and genetic changes. We used ten‐year demo‐genetic monitoring to test 1) whether demographic declines were associated with genetic diversity declines and 2) whether the spatial structure of a metapopulation can weaken or reinforce these demographic and genetic temporal trends. We continuously surveyed, over time and across their entire range, two metapopulations of an endemic freshwater fish species Leuciscus burdigalensis: one metapopulation that had experienced a recent demographic decline and a second metapopulation that was stable over time. In the declining metapopulation, the number of alleles rapidly decreased, the inbreeding coefficient increased, and a genetic bottleneck emerged over time. In contrast, genetic indices were constant over time in the stable metapopulation. We further show that, in the declining metapopulation, demographic and genetic declines were not homogeneously distributed across the metapopulation. We notably identify one local population situated downstream as a ‘reservoir’ of individuals and genetic variability that dampens both the demographic and genetic declines measured at the metapopulation level. We demonstrate the usefulness of long‐term monitoring that combines both genetic and demographic parameters to understand and predict temporal population fluctuations of at‐risk species living in a metapopulation context.     

Metapopulation Dynamics of the Mistletoe and Its Host in Savanna Areas with Different Fire Occurrence

Mistletoes are aerial hemiparasitic plants which occupy patches of favorable habitat (host trees) surrounded by unfavorable habitat and may be possibly modeled as a metapopulation. A metapopulation is defined as a subdivided population that persists due to the balance between colonization and extinction in discrete habitat patches. Our aim was to evaluate the dynamics of the mistletoe Psittacanthus robustus and its host Vochysia thyrsoidea in three Brazilian savanna areas using a metapopulation approach. We also evaluated how the differences in terms of fire occurrence affected the dynamic of those populations (two areas burned during the study and one was fire protected). We monitored the populations at six-month intervals. P. robustus population structure and dynamics met the expected criteria for a metapopulation: i) the suitable habitats for the mistletoe occur in discrete patches; (ii) local populations went extinct during the study and (iii) colonization of previously non-occupied patches occurred. The ratio of occupied patches decreased in all areas with time. Local mistletoe populations went extinct due to two different causes: patch extinction in area with no fire and fire killing in the burned areas. In a burned area, the largest decrease of occupied patch ratios occurred due to a fire event that killed the parasites without, however, killing the host trees. The greatest mortality of V. thyrsoidea occurred in the area without fire. In this area, all the dead trees supported mistletoe individuals and no mortality was observed for parasite-free trees. Because P. robustus is a fire sensitive species and V. thyrsoidea is fire tolerant, P. robustus seems to increase host mortality, but its effect is lessened by periodic burning that reduces the parasite loads.     

Linking extinction-colonization dynamics to genetic structure in a salamander metapopulation

Theory predicts that founder effects have a primary role in determining metapopulation genetic structure. However, ecological factors that affect extinction-colonization dynamics may also create spatial variation in the strength of genetic drift and migration. We tested the hypothesis that ecological factors underlying extinction-colonization dynamics influenced the genetic structure of a tiger salamander (Ambystoma tigrinum) metapopulation. We used empirical data on metapopulation dynamics to make a priori predictions about the effects of population age and ecological factors on genetic diversity and divergence among 41 populations. Metapopulation dynamics of A. tigrinum depended on wetland area, connectivity and presence of predatory fish. We found that newly colonized populations were more genetically differentiated than established populations, suggesting that founder effects influenced genetic structure. However, ecological drivers of metapopulation dynamics were more important than age in predicting genetic structure. Consistent with demographic predictions from metapopulation theory, genetic diversity and divergence depended on wetland area and connectivity. Divergence was greatest in small, isolated wetlands where genetic diversity was low. Our results show that ecological factors underlying metapopulation dynamics can be key determinants of spatial genetic structure, and that habitat area and isolation may mediate the contributions of drift and migration to divergence and evolution in local populations.     

The genetic status of the violet copper Lycaena helle– a relict of the cold past in times of global warming

Rising temperatures and agricultural changes (intensification and succession on fallow land) during the last few decades have caused a strong decline of moist and cool sites on nutrient-poor grasslands and species depending on these habitats. We tested the effects of habitat deterioration on a local and regional scale in such a species, the highly endangered butterfly Lycaena helle , which was more widely distributed over central Europe during the postglacial period, but has recently become restricted to some remnants. We analysed five polymorphic microsatellite loci in 220 individuals sampled at ten different localities. The study sites in Germany, Luxembourg and Belgium are geographically split into three mountain regions: the Ardennes, the Eifel and the Westerwald; the latter is separated from the other two by the river Rhine. A comparatively high genetic diversity was detected in all local populations and genetic differentiation was found among the Ardennes, the Eifel and the Westerwald (F_CT: 0.084). The genetic differentiation among all populations (F_ST: 0.137) underlines natural and anthropogenic habitat fragmentation. While ongoing gene flow seems to exist among the Eifel populations indicating the only intact metapopulation, a high genetic differentiation in the Ardennes and the Westerwald indicates a disruption of population connectivity. Our genetic data obtained on different spatial scales show the genetic consequence of long-term isolation and should trigger necessary conservation measures at the metapopulation level.     

Genetic diversity and conservation of Ipomoea microdactyla (Convolvulaceae): an endemic vine from the Bahamas,Cuba, and southeastern Florida

Ipomoea microdactyla Griseb. (Convolvulaceae) is restricted to the Bahamian archipelago, Cuba, and southeastern Florida. The species is listed as a state endangered species in Florida, where it is mostly restricted to the hyperfragmented pine rockland of Miami‐Dade County. Using seven DNA microsatellite loci, we assessed levels of genetic diversity for 12 populations of this species from Andros Island in the Bahamas (six sites), Cuba (one site), and Florida (five sites). We found significantly greater mean numbers of alleles, and higher mean values for both observed and expected heterozygosity in populations from the continuous forest on Andros than those from the habitat fragments in Florida. It is unknown if these patterns of genetic diversity in the Florida populations are the result of habitat fragmentation or founder effects. The population from Cuba exhibited relatively high levels of genetic variation, suggesting that this island is a major center of diversity and dispersal for this species. It appears that hybrid introgression for I. carolina alleles within I. microdactyla individuals occurred at a single site on Andros Island. Overall, the mean inbreeding coefficient value was 0.089, suggesting low levels of inbreeding. The highest inbreeding coefficient values were mostly recorded in Florida. Two groups were revealed, one containing the populations from Florida, and the second one encompassing those from the Bahamas and Cuba. Our results highlight the negative genetic consequences of habitat fragmentation and support initiatives recently established to establish corridors to connect the remnants of the pine forest of the Miami‐Dade County.     

Genetic spatial structure in a butterfly metapopulation correlates better with past than present demographic structure

The Glanville fritillary butterfly ( Melitaea cinxia ) has been studied in the Åland Islands in Finland since 1991, where it occurs as a classic metapopulation in a large network of 4000 dry meadows. Much ecological work has been conducted on this species, but population genetic studies have been hampered by paucity of suitable genetic markers. Here, using single nucleotide polymorphisms and microsatellites developed for the Glanville fritillary, we examine the correspondence between the demographic and genetic spatial structures. Given the dynamic nature of the metapopulation, the current genetic spatial structure may bear a signal of past changes in population sizes and past patterns of gene flow rather than reflect the current demographic structure or landscape structure. We analyse this question with demographic data for 10 years, using the Rand index to assess the similarity between the genetic, demographic, and landscape spatial structures. Our results show that the current genetic spatial structure is better explained by the past rather than by the current demographic spatial structure or by the spatial configuration of the habitat in the landscape. Furthermore, current genetic diversity is significantly explained by past metapopulation sizes. The time lag between major demographic events and change in the genetic spatial structure and diversity has implications for the study of spatial dynamics.     

Ecological determinants and temporal stability of the within-river population structure in Atlantic salmon (Salmo salar L.)

A gene diversity analysis was performed using microsatellite loci in order to (i) describe the extent and pattern of population structure in Atlantic salmon (Salmo salar L.) within a river system; (ii) establish the importance of quantifying the signal:noise ratio in accurately estimating population structure; and (iii) assess the potential usefulness of two evolutionary models in explaining within-river population structure from the ecological and habitat characteristics of Atlantic salmon. We found weak, yet highly significant microscale spatial patterning after accounting for variance among temporal replicates within sites. Lower genetic distances were observed among temporal samples at four sampling sites whereas no evidence for temporal stability was observed at the other three locations. The component of genetic variance attributable to either temporal instability and/or random sampling errors was almost three times more important than the pure spatial component. This indicates that not considering signal:noise ratio may lead to an important overestimation of genetic substructuring in situations of weak genetic differentiation. This study also illustrates the usefulness of the member-vagrant hypothesis to generate a priori predictions regarding the number of subpopulations that should compose a species, given its life-history characteristics and habitat structure. On the other hand, a metapopulation model appears better suited to explain the extent of genetic divergence among subpopulations, as well as its temporal persistence, given the reality of habitat patchiness and environment instability. We thus conclude that the combined use of both models may offer a promising avenue for studies aiming to understand the dynamics of genetic structure of species found in unstable environments.     

Genetic restoration in the eastern collared lizard under prescribed woodland burning

Eastern collared lizards of the Ozarks live in glades—open, rocky habitats embedded in a woodland matrix. Past fire suppression had made the woodlands a barrier to dispersal, leading to habitat destruction, fragmentation and local extinction. Reintroduced populations of lizards were subjected to 10 years of habitat fragmentation under continued fire suppression followed by twelve years of landscape restoration with prescribed burns. Prior to prescribed burning, genetic diversity decreased within glades and differentiation increased among glades. With woodland burning, genetic diversity within glades first decreased during an expanding colonization phase, but then increased as a dynamically stable metapopulation was established. Population differentiation among glades also stabilized in the metapopulation under weak isolation‐by‐distance. This study is one of the first to examine the genetic changes in a species of conservation concern throughout all the stages of decline and recovery and shows the importance of landscape‐level restoration for maintaining the genetic integrity of populations. This study also demonstrates how mark–recapture and genetic data together can yield detailed insight into metapopulation dynamics that would be impossible from just one type of data alone.     

Diversity and community composition of butterflies and odonates in an ENSO-induced fire affected habitat mosaic: a case study from East Kalimantan, Indonesia

Little is known about the diversity of tropical animal communities in recently fire‐affected environments. Here we assessed species richness, evenness, and community similarity of butterflies and odonates in landscapes located in unburned isolates and burned areas in a habitat mosaic that was severely affected by the 1997/98 ENSO (El Niño Southern Oscillation) event in east Kalimantan, Indonesian Borneo. In addition related community similarity to variation in geographic distance between sampling sites and the habitat/vegetation structure Species richness and evenness differed significantly among landscapes but there was no congruence between both taxa. The species richness of butterflies was, for example, highest in sites located in a very large unburned isolate whereas odonate species richness was highest in sites located in a small unburned isolate and once‐burned forest. We also found substantial variation in the habitat/vegetation structure among landscapes but this was mainly due to variation between unburned and burned landscapes and variation among burned landscapes. Both distance and environment (habitat/vegetation) contributed substantially to explaining variation in the community similarity (beta diversity) of both taxa. The contribution of the environment was, however, mainly due to variation between unburned and burned landscapes, which contained very different assemblages of both taxa. Sites located in the burned forest contained assemblages that were intermediate between assemblages from sites in unburned forest and sites from a highly degraded slash‐and‐burn area indicating that the burned forest was probably recolonised by species from these disparate environments. We, furthermore, note that in contrast to species richness (alpha diversity) the patterns of community similarity (beta diversity) were highly congruent between both taxa. These results indicate that community‐wide multivariate measures of beta diversity are more consistent among taxa and more reliable indicators of disturbance, such as ENSO‐induced burning, than univariate measures.     

Demographic and genetic factors shaping contemporary metapopulation effective size and its empirical estimation in salmonid fish

The preservation of biodiversity requires an understanding of the maintenance of its components, including genetic diversity. Effective population size determines the amount of genetic variance maintained in populations, but its estimation can be complex, especially when populations are interconnected in a metapopulation. Theory predicts that the effective size of a metapopulation (meta-N(e)) can be decreased or increased by population subdivision, but little empirical work has evaluated these predictions. Here, we use neutral genetic markers and simulations to estimate the effective size of a putative metapopulation in Atlantic salmon (Salmo salar). For a weakly structured set of rivers, we find that meta-N(e) is similar to the sum of local deme sizes, whereas higher genetic differentiation among demes dramatically reduces meta-N(e) estimates. Interdemic demographic processes, such as asymmetrical gene flow, may explain this pattern. However, simulations also suggest that unrecognized population subdivision can also introduce downward bias into empirical estimation, emphasizing the importance of identifying the proper scale of distinct demographic and genetic processes. Under natural patterns of connectivity, evolutionary potential may generally be maintained at higher levels than the local population, with implications for conservation given ongoing species declines and habitat fragmentation.     

Population genomics of rapidly invading lionfish in the Caribbean reveals signals of range expansion in the absence of spatial population structure

Range expansions driven by global change and species invasions may have significant genomic, evolutionary, and ecological implications. During range expansions, strong genetic drift characterized by repeated founder events can result in decreased genetic diversity with increased distance from the center of the historic range, or the point of invasion. The invasion of the Indo‐Pacific lionfish, Pterois volitans, into waters off the US East Coast, Gulf of Mexico, and Caribbean Sea provides a natural system to study rapid range expansion in an invasive marine fish with high dispersal capabilities. We report results from 12,759 single nucleotide polymorphism loci sequenced by restriction enzyme‐associated DNA sequencing for nine P. volitans sampling areas in the invaded range, including Florida and other sites throughout the Caribbean, as well as mitochondrial control region D‐loop data. Analyses revealed low to no spatially explicit metapopulation genetic structure, which is partly consistent with previous finding of little structure within ocean basins, but partly divergent from initial reports of between‐basin structure. Genetic diversity, however, was not homogeneous across all sampled sites. Patterns of genetic diversity correlate with invasion pathway. Observed heterozygosity, averaged across all loci within a population, decreases with distance from Florida while expected heterozygosity is mostly constant in sampled populations, indicating population genetic disequilibrium correlated with distance from the point of invasion. Using an F_ST outlier analysis and a Bayesian environmental correlation analysis, we identified 256 and 616 loci, respectively, that could be experiencing selection or genetic drift. Of these, 24 loci were shared between the two methods.     

Effects of re‐introducing fire to a central Florida sandhill community

Abstract. A southern ridge sandhill site in central Florida, USA, was burned in 1989, 1991, and 1995 after 63 years of fire‐suppression to simulate a pre‐settlement fire regime. Fire changed species abundance and vegetation structure but caused only minimal changes in species turnover and diversity. There was a general trend for an increase in the cover of herbs following fire but this was a statistically significant effect for only one species, Liatris tenuifolia var. tenuifolia. Aristida beyrichiana increased, litter cover and litter depth were significantly reduced, and ground lichens were eliminated in response to burning. Scrub oaks and palmettos in the ground cover and small shrub layers (height ≤ 1 m) either increased or did not respond to burning, reflecting strong post‐fire resprouting. Diversity in the ground cover and small shrub layers were not affected by fire. Scrub oaks and palmettos in the large shrub and overstorey layers (height > 1 m) were reduced in density, basal area, and longest canopy measurements in response to fire. Species diversity also decreased within these layers following fire. Some Pinus elliottii var. densa survived fire, but their density was reduced. All Pinus clausa were eliminated by fire. Periodic burning can suppress the dominance of shrubs (Quercus spp.) while increasing the cover of grasses and herbs in southern ridge sandhill vegetation.     

Effects of repeated burning on species richness in a Florida pine savanna: A test of the intermediate disturbance hypothesis

Abstract. We studied the effect of burning frequency on the density and species richness of understory flowering stems in a Florida sandhill. Flowering stems were censused weekly for 54 weeks in six sites that had been burned one to six times in the previous 16 years. We concurrently measured overstory characteristics such as species composition, density and basal area. We used maximum likelihood and Akaike's Information Criterion to compare linear, quadratic, saturating, and null models of community response to repeating burning. We did not find a relationship between species richness, diversity or flowering stem density and fire frequency. Tree density was related to fire frequency and may represent an indirect pathway for fire effects on understory characteristics. While we found no support for the Intermediate Disturbance Hypothesis, an analysis of our experimental design indicated that we had low statistical power. We develop the hypothesis that a saturating model of response to fire best describes understory species richness in our system. We test this hypothesis using the most extensive published fire data set we are aware of and find support for a saturating model.     

Rare long-distance dispersal of the Island Night Lizard, <Emphasis Type="Italic">Xantusia riversiana</Emphasis>, maintains high diversity in a fragmented environment

The Island Night Lizard (Xantusia riversiana) is endemic to three of the Channel Islands off the coast of California, USA. Introduced species such as goats, sheep, and cats have profoundly affected the fauna and flora of the islands for over 150 years, but most of these non-native species have been recently removed. We measured the distribution of genetic diversity in Island Night Lizards across San Nicolas Island using DNA microsatellites to assess the impacts of historical habitat change on effective population size, gene flow, and population divergence; to provide baseline data for future monitoring of genetic diversity; and to provide recommendations to inform the restoration of degraded habitat. Despite a history of profound anthropogenic habitat disturbance, genetic diversity was high within sites, and there was no evidence of population bottlenecks. Divergence between sites was extraordinarily high, as expected for this sedentary species. Landscape resistance modeling using circuit theory showed that unsuitable habitat is relatively permeable to gene flow compared to suitable habitat, and yet populations separated by very short geographic distances remain genetically distinct. We found no evidence of a need for short-term intervention such as artificial translocations to maintain genetic diversity. Instead, we suggest that management should focus on maintaining, improving, and increasing habitat, especially in creating patches of habitat to link existing sites.     

Habitat predictors of genetic diversity for two sympatric wetland‐breeding amphibian species

Population genetic diversity is widely accepted as important to the conservation and management of wildlife. However, habitat features may differentially affect evolutionary processes that facilitate population genetic diversity among sympatric species. We measured genetic diversity for two pond‐breeding amphibian species (Dwarf salamanders, Eurycea quadridigitata; and Southern Leopard frogs, Lithobates sphenocephalus) to understand how habitat characteristics and spatial scale affect genetic diversity across a landscape. Samples were collected from wetlands on a longleaf pine reserve in Georgia. We genotyped microsatellite loci for both species to assess population structures and determine which habitat features were most closely associated with observed heterozygosity and rarefied allelic richness. Both species exhibited significant population genetic structure; however, structure in Southern Leopard frogs was driven primarily by one outlier site. Dwarf salamander allelic richness was greater at sites with less surrounding road area within 0.5 km and more wetland area within 1.0 and 2.5 km, and heterozygosity was greater at sites with more wetland area within 0.5 km. In contrast, neither measure of Southern Leopard frog genetic diversity was associated with any habitat features at any scale we evaluated. Genetic diversity in the Dwarf salamander was strongly associated with land cover variables up to 2.5 km away from breeding wetlands, and/or results suggest that minimizing roads in wetland buffers may be beneficial to the maintenance of population genetic diversity. This study suggests that patterns of genetic differentiation and genetic diversity have associations with different habitat features across different spatial scales for two syntopic pond‐breeding amphibian species.     

Isolation of microsatellite loci in the Florida Scrub‐Jay Aphelocoma coerulescens

The Florida Scrub‐Jay (Aphelocoma coerulescens), a habitat specialist listed as Threatened by the U.S. Fish and Wildlife Service, exhibits extremely limited natal dispersal. We hypothesize that this behaviour results in a correlation of genetic and geographical distance. To test this, we are sampling intensively along the north–south orientated Lake Wales Ridge of central Florida. We describe the isolation and characterization of 31 microsatellite loci developed to determine the minimum distance at which genetic structure can be detected, and to test for isolation by distance. There are 3–15 alleles per locus, with expected heterozygosities from 0.16 to 0.86.