Fine-scale Spatial Patterns Research Articles

Spatial scaling in the phylogeography of an alpine caddisfly,Allogamus uncatus, within the central European Alps

AbstractBoth historical and contemporary processes can influence population genetic structure and phylogeographic patterns at different spatial scales. We studied the genetic structure of a common alpine caddisfly, Allogamus uncatus, across the central European Alps using mitochondrial cytochrome oxidase c subunit I (COI) sequence data to evaluate broad- and fine-scale spatial patterns in population genetic structure and examined how these patterns relate to historical and contemporary landscape processes. Both historical and contemporary influences on population genetic structure could be distinguished. At the broad-scale, our results showed the existence of 6 geographically structured haplogroups across the central Alps that were derived from 4 deeply diverged (up to 5.5%) older lineages. This broad-scale pattern in genetic structure of A. uncatus probably was the result of recolonization from multiple glacial refugia peripheral to the Alps. These data support the idea that phylogeographic patterns invo...

Regional modelling of soil carbon at multiple depths within a subtropical watershed

Environmental factors that exert control over fine-scale spatial patterns of soil organic carbon (SOC) within profiles and across large regions differ by geographic location and landscape setting. Regions with large SOC storage and high variability can serve as natural laboratories to investigate how environmental factors generate vertical and horizontal SOC patterns across the landscape. This was investigated in the Santa Fe River watershed (SFRW), Florida, where we modelled the spatial distribution of total C (TC) at four depths to 180 cm (0–30, 30–60, 60–120, and 120–180 cm) and at an aggregated depth of 0–100 cm. A total of 554 samples from 141 sampling sites distributed along land use and soil order combinations were analyzed for TC by high-temperature combustion. A vertical trend of TC stocks decreasing with depth was identified. Horizontal trends of TC were modelled to identify the environmental determinants of TC in the SFRW. We used analysis of variance (ANOVA) and compared regression block kriging with lognormal block kriging to scale up TC across the SFRW. Total soil C was influenced by soil depth, land use, soil type, soil drainage class, and geologic unit. Regression kriging performed better than block kriging to scale up TC at three out of five depth intervals. This indicates that in the majority of cases environmental factors were the major determinants of the spatial distribution of TC relative to its spatial autocorrelation. At 60–120 and 120–180 cm, the local spatial dependence of TC was more important than environmental factors to explain its variation across the watershed. Our models show that 54.0 Tg (teragrams) of C is held in the upper 1 m of soils in the SFRW, and significant amounts are stored in deeper layers. They also identified the major factors responsible for regional spatial patterns of TC in this subtropical region, providing information to support current efforts of conservation of soil resources in Florida, and under similar environmental conditions in the southeastern U.S. and elsewhere.

Strong philopatry derived from capture–recapture records does not lead to fine‐scale genetic differentiation in lesser kestrels

1. The integration of capture-recapture and molecular approaches can improve our understanding of the consequences of habitat fragmentation on population connectivity. Here we employed microsatellites to test dispersal hypotheses derived from intense and long-term ringing programmes of the lesser kestrel Falco naumanni in Western Europe. 2. Re-encounters of 1308 marked individuals in Spain have revealed that most first-time breeders settled within 10 km from their natal colony, with a negative association between dispersal and geographical distance. Although these findings would predict fine-scale spatial patterns of genetic differentiation, the genetic impact of rarely reported events concerning long-distance effective dispersal (> 100 km) is unknown. 3. First, we investigated a spatially structured and geographically isolated population located in north-eastern Spain, where capture-recapture records and genetic data could be appropriately compared over similar spatial and temporal scales. Spatial autocorrelation analyses (N = 174 nestlings from different broods) did not reveal either significant differences in average relatedness at any distance class nor decreased relatedness as a function of distance. At a broader spatial scale, Bayesian analysis of population structure (N = 432 nestlings) indicated panmixia across Western Europe. However, F(ST) comparisons between four geographically distinct populations indicated low but significant genetic differentiation. 4. Our genetic data would therefore challenge traditional assumptions associating philopatry with the emergence of fine-scale genetic structuring. This could be because even low levels of gene flow are enough to preclude the development of local genetic structure. Nevertheless, the analysis of a geographically isolated and small population from Southern France exemplifies a situation in which restricted dispersal has translated into weak but consistently significant genetic differentiation. 5. Relevant to conservation genetics and evolutionary biology, our results may lessen the genetic concerns derived from population fragmentation at relatively small geographical scales in species with apparently limited dispersal abilities, but raises concerns about increased genetic divergence in small and isolated demes.

Patrons spatio-temporels d’émergence et de croissance initiale des semis de deux espèces de chênes semées dans un pâturage abandonné

• Fine-scale spatial and temporal establishment patterns of direct-seeded oaks on abandoned agricultural land have been little studied despite their potential importance for long-term stand structure. • Here we periodically monitored seedling emergence and early growth of bur oak (Quercus macrocarpa Michx.) and red oak (Q. rubra L.) on an abandoned pasture, and tested the effects of herbaceous competition, rodents, and soil physicochemical properties. • Herbaceous competition slightly decreased diameter growth, but rodents had little impact on establishment. Red oak seedlings emerged earlier than bur oak and in a greater proportion (92% vs. 56%). Seedling emergence and early growth of both species showed significant spatial structures that were partly explained by variation in soil physicochemical properties. Bur oak was more responsive to microenvironmental heterogeneity than red oak, yet much of the variation in emergence and growth of both species remained unexplained. • This suggests that other factors, such as acorn size or genetic variability, may exert equal or greater control than microenvironmental heterogeneity over seedling emergence and early growth of these two oak species on abandoned pastureland.

Need for Improved Methods to Collect and Present Spatial Epidemiologic Data for Vectorborne Diseases

Improved methods for collection and presentation of spatial epidemiologic data are needed for vectorborne diseases in the United States. Lack of reliable data for probable pathogen exposure site has emerged as a major obstacle to the development of predictive spatial risk models. Although plague case investigations can serve as a model for how to ideally generate needed information, this comprehensive approach is cost-prohibitive for more common and less severe diseases. New methods are urgently needed to determine probable pathogen exposure sites that will yield reliable results while taking into account economic and time constraints of the public health system and attending physicians. Recent data demonstrate the need for a change from use of the county spatial unit for presentation of incidence of vectorborne diseases to more precise ZIP code or census tract scales. Such fine-scale spatial risk patterns can be communicated to the public and medical community through Web-mapping approaches.

Can Modeling of Fine-Scale Spatial Patterns of Environmental Markers of Zoonotic Infections Enhance Disease Prevention and Clinical Outcomes?

When evaluating patients with an undiagnosed infectious disease, physicians in general (and infectious disease specialists in particular) are trained to obtain a history of factors such as recent travel, location of residence, country of birth, occupation, and contact with animals. These factors are taken into account when generating a ranked differential diagnosis. For example, a history of work as a professional landscaper in the setting of a compatible clinical presentation would likely trigger specific diagnostic testing and presumptive treatment of tularemia. 1 Unfortunately, physicians generally lack the expertise to identify factors such as specific ecotones associated with risk of zoonotic infections. On the other hand, infectious disease ecologists and epidemiologists consider the role of the environment to be critical in vector-borne and zoonotic disease transmission, 2–4 and they are increasingly aware of the need to consider the effective range of transmission overlap of several pathogens, model the potential benefits of integrated control, and define the environmentally appropriate level for control efforts. 5,6 In this issue, Eisen and others 7 report the development of a fine-scale model to predict the risk of plague and hantavirus infection in humans in northwestern New Mexico and northeastern Arizona. The environmental risk of plague was related to precipitation and distance to pinon-juniper ecotones, whereas the risk of hantavirus infection was related to precipitation and elevation; half the area had risk for both zoonotic infections. The authors suggest that fine-scale identification of areas of increased disease risk would be useful for targeting education activities, resulting in improved disease prevention and management. Targeting disease prevention activities for these significant, rodent-borne infections should at a minimum lead to more efficient use of public health funding, which in turn could lead to more effective prevention activities. Education of healthcare providers also might lead to some improvement in disease management, but it is not clear whether targeted education with training on fine-scale identification of areas of increased disease risk or targeting training in areas of increased risk would be more effective than general, regional educational activities without this training. Early initiation of appropriate antibiotic therapy for plague reduces mortality; management by an experienced critical care team in a tertiary care center, including extracorporeal membrane oxygenation (ECMO) in some centers, reduces mortality in severe hantavirus cardiopulmonary syndrome (HCPS), also known as hantavirus pulmonary syndrome. 8–10

Spatial heterogeneity and dependence of soils and herbaceous plant communities in adjacent seasonal wetland and pasture sites

ABSTRACT Soil processes often exhibit spatial heterogeneity that may influence plant community structure. This study was conducted to determine fine-scale spatial patterns and degrees of variability of soil nutrients and plant communities within different vegetation types in a stream floodplain in southwestern West Virginia. One 5 m × 5 m site was established in each of two vegetation/drainage types: pasture (PA) and seasonal wetland (SW). Sites were located ∼25 m apart on flat bottomland. A 10 m × 1 m transect was also established perpendicular to the visible boundary between PA and SW drainage types, but separate from the PA and SW sites. Each site was divided into 1-m2 plots (n = 25) and the transect was divided into 0.25-m2 plots (n = 40). Mineral soil was taken to a 5 cm depth. Soil organic matter was measured as loss-on-ignition. Extractable NH4+ and NO3− were determined before and after laboratory incubation (28 days at 27°C) to determine net N mineralization and nitrification. Cations were ana...

Weak and variable relationships between environmental severity and small‐scale co‐occurrence in alpine plant communities

Summary 1. The stress gradient hypothesis suggests a shift from predominant competition to facilitation along gradients of increasing environmental severity. This shift is proposed to cause parallel changes from prevailing spatial segregation to aggregation among the species within a community. 2. We used 904 1-m 2 plots, each subdivided into 100 10 × 10 cm, or 25 20 × 20 cm cells, respectively, from 67 European mountain summits grouped into 18 regional altitudinal transects, to test this hypothesized correlation between fine-scale spatial patterns and environmental severity. 3. The data were analysed by first calculating standardized differences between observed and simulated random co-occurrence patterns for each plot. These standardized effect sizes were correlated to indicators of environmental severity by means of linear mixed models. In a factorial design, separate analyses were made for four different indicators of environmental severity (the mean temperature of the coldest month, the temperature sum of the growing season, the altitude above tree line, and the percentage cover of vascular plants in the whole plot), four different species groups (all species, graminoids, herbs, and all growth forms considered as pseudospecies) and at the 10 × 10 cm and 20 × 20 cm grain sizes.

Monitoring spatio-temporal variation in molluscan grazing pressure in seasonal, tropical rock pools

In Hong Kong, low-shore rock pools support a patchy mosaic of different successional stages of crustose coralline algae. Echinoid and molluscan grazers are abundant in these low-shore rock pools and spatial and temporal variation in grazing pressure is thought to play an important role in structuring these assemblages. Direct records of graze marks using a modified wax-disc method were used to monitor spatial (different pools) and temporal (periods, 3 or 4 days each; spring vs. neap tides; summer vs. winter) variations in grazing pressure. Radula marks of Chlorostoma argyrostoma, Lunella coronata and Nerita albicilla were common in all pools. Grazing pressure was highly variable with tidal state and season but also within these two factors. Lunella and Nerita exerted highest grazing pressure at neap tides during summer, whilst Chlorostoma exerted highest grazing pressure in winter. Although overall patterns of temporal variation were similar and consistent in all pools, there was between pool variation in grazing pressure and individual species showed different patterns. Within the seasonal and tidal variations, large period-to-period differences were found for all species, illustrating small-scale temporal variation. Fine-scale spatial and temporal patterns of variation in grazing pressure of different species, therefore, contribute to the highly dynamic nature of these low-shore rock pools.

Simulation and quantification of the fine-scale spatial pattern and heterogeneity of forest canopy structure: A lacunarity-based method designed for analysis of continuous canopy heights

Forests canopies are dynamic, continuously varying, three-dimensional structures that display substantial heterogeneity in their spatial arrangement at many scales. At the stand-level, fine-scale spatial heterogeneity influences key canopy processes and contributes to the diversity of niche space and maintenance of forest biodiversity. We present a quantitative method that we developed based on a novel application of two well-established statistical techniques – lacunarity analysis and principal component analysis (PCA) – to determine the fine-scale (0.5–33 m) spatial heterogeneity found in the outer surface of a forest canopy. This method was specifically designed for the analysis of continuous canopy height data generated by airborne LiDAR systems or digital photogrammetry; however, in this study we demonstrate our method using a large, well-documented dataset composed of simulated canopy surfaces only. We found that the magnitude of the lacunarity statistic was strongly associated with canopy cover ( R 2 = 0.85) and gap volume ( R 2 = 0.84), while the pattern of decline in lacunarity across discrete measurement scales was related to many size- and density-related attributes of stand and canopy structure (0.27 ≤ R 2 ≤ 0.58) and their diverse vertical and horizontal spatial distributions. PCA uncovered two major gradients of spatial heterogeneity from the 10 dimensions of our original lacunarity dataset. The stronger of these two gradients reflected the continuous variation in canopy cover and gap volume, while a second, more subtle gradient was associated with the array of possible vertical and horizontal spatial configurations that might define any one measure of canopy cover. We expect that this quantitative method can be used to support a broad range of practical applications in sustainable forest management, long-term ecological monitoring, and forest science. Further research is required to understand how these statistical estimates and gradients of measured spatial heterogeneity relate to other ecologically relevant patterns of forest composition, structure, and function.

Reconstructing fire regimes with charcoal from small-hollow sediments: a calibration with tree-ring records of fire

Interpretations of charcoal records from small hollows lack a strong theoretical and empirical foundation, and thus their potential for providing useful fire-history records is unclear. To evaluate this potential, we examined charcoal records in 210Pb-dated cores from 12 small hollows and looked for evidence of 20 local fires reconstructed with tree-ring records from the surrounding forest. Using all charcoal > 0.15 mm wide we established an optimum threshold that identified charcoal peaks corresponding to known fires while minimizing charcoal peaks identified that were not associated with known fires (i.e., false positives). This threshold detected four of four high-severity fires, five of 10 moderate-severity fires, and three of six low-severity fires. Analysis of larger charcoal alone (> 0.50 mm wide) yielded nearly identical temporal patterns and detection rates, but four false positives were identified, twice as many as identified using all charcoal >0.15 mm wide. Charcoal peak magnitude was highly variable within severity classes: although half of the low-and moderate-severity fires left no detectable peaks, others left peaks larger than some high-severity fires. Our results suggest that fire detection depends strongly on fire severity and that fine-scale spatial patterns of lower-severity burns play an important role in determining the charcoal signature of these events. High detection rates for high-severity fires and low false-positive rates indicate that charcoal records from small hollows will be most useful in systems where fires are large, severe and infrequent.

Fine-scale spatial patterns of recruitment in red oak (Quercus rubra): What matters most, abiotic or biotic factors?

:Seedling recruitment in temperate oaks is expected to depend mostly on biotic filters, given the relative independence from resource limitation conferred by large seed size. We investigated the magnitude and fine-scale spatial pattern of red oak (Quercus rubra) recruitment in a mature forest in southern Québec. We compared the scale of operation of experimentally assessed seed and seedling predation to that of several abiotic factors. We sought to interpret concordance or discordance between seed rain and seedling recruitment in terms of spatial heterogeneity in these environmental filters. Most of the demographic variables (adult leaf area index [LAI] and seed rain, newly emerged seedling, and recruited seedling densities) were highly heterogeneous and structured at fine spatial scales. Topography, soil moisture, and light, but not litter thickness, also showed significant spatial autocorrelation at fine spatial scales. However, most of the biotic filters (e.g., seed removal, seed germination, and seedling mortality) were not spatially structured, except for clipping by voles, which was significantly autocorrelated at small distance classes. Failure to detect autocorrelation in most of the biotic filters suggests that they may operate at scales different from that studied, e.g., at a coarser scale for seed predation, but at a finer scale for insect folivory. A path analysis revealed that a large proportion of the variance in seedling recruitment was the result of direct links between the demographic variables studied. Another path analysis, accounting for the effects of biotic filters, highlighted the critical role played by seed predators on recruitment. However, restricted seed dispersal was the major factor influencing the spatial distribution of recruits: indeed, spatial concordance between seed rain and recruit density suggested that even when they are heterogeneous at the same spatial scale, environmental filters are not strong enough to disrupt the patterns generated by primary seed dispersal. Hoarding by rodents accounted for a significant proportion of the spatially homogeneous seed removal; it also reduced potential recruitment limitation associated with microsite availability, thereby increasing the proportion of variation in the spatial pattern of recruitment accounted for by primary seed dispersal.

Fine‐scale spatial genetic correlation analyses reveal strong female philopatry within a brush‐tailed rock‐wallaby colony in southeast Queensland

We combine spatial data on home ranges of individuals and microsatellite markers to examine patterns of fine-scale spatial genetic structure and dispersal within a brush-tailed rock-wallaby (Petrogale penicillata) colony at Hurdle Creek Valley, Queensland. Brush-tailed rock-wallabies were once abundant and widespread throughout the rocky terrain of southeastern Australia; however, populations are nearly extinct in the south of their range and in decline elsewhere. We use pairwise relatedness measures and a recent multilocus spatial autocorrelation analysis to test the hypotheses that in this species, within-colony dispersal is male-biased and that female philopatry results in spatial clusters of related females within the colony. We provide clear evidence for strong female philopatry and male-biased dispersal within this rock-wallaby colony. There was a strong, significant negative correlation between pairwise relatedness and geographical distance of individual females along only 800 m of cliff line. Spatial genetic autocorrelation analyses showed significant positive correlation for females in close proximity to each other and revealed a genetic neighbourhood size of only 600 m for females. Our study is the first to report on the fine-scale spatial genetic structure within a rock-wallaby colony and we provide the first robust evidence for strong female philopatry and spatial clustering of related females within this taxon. We discuss the ecological and conservation implications of our findings for rock-wallabies, as well as the importance of fine-scale spatial genetic patterns in studies of dispersal behaviour.

Coenostate descriptors and spatial dependence in vegetation - derived variables in monitoring forest dynamics and assembly rules

Long term vegetation monitoring provides valuable information on spatio-temporal patterns in plant communities that could be analysed to detect spatial relationship changes among species and to interpret dynamic tendencies and assembly rules in non-equilibrium phytocoenoses. In studies of this kind, one should take into account recent ecological theories emphasizing the scale dependence of vegetation; in particular, fine-scale spatial patterns of vegetation are important constraints in the genesis and maintenance of diversity. The information theory models of Juhasz-Nagy offer an appropriate tool for describing the relationship between diversity and multispecies spatial dependence in vegetation. Diversity (florula diversity) and spatial dependence (associatum) are calculated for a series of increasing plot sizes (spatial scaling). The plot sizes at which the two coenostate descriptors reach the maximum information represent the characteristic scales that should be considered as optimal plot sizes in monit...

Patterns in pitfall captures of millipedes (Diplopoda: Polydesmida: Paradoxosomatidae) at coastal heathland sites in Tasmania

The millipede by-catch from a 1986-88 spider survey in Tasmanian coastal heathland was tallied by species, sex and life-stage. Two species of paradoxosomatid Polydesmida, Notodesmus scotius Chamberlin, 1920 and Pogonosternum sp., made up 99.8% of the pitfall captures. The N. scotius catch (9754 individuals) was 80% adult (stadium VIII) and peaked in October-December with only 23 captures in July-September. The Pogonosternum sp. catch (116 individuals) was 91% adult and peaked in September, with 40% of all captures in July-September. These results, together with field observations, indicate that pitfall trapping mainly captured adults wandering during the mating season, and that mating seasons for the two species did not coincide. The Pogonosternum sp. captures were tightly clustered in space, showing that pitfall trapping can be an unreliable method for estimating millipede abundance unless the fine-scale spatial patterning of target species is known in advance. A third paradoxosomatid species known to be...

Fine scale genetic structure in a wild soybean (Glycine soja) population and the implications for conservation.

• The fine-scale spatial distribution of a wild soybean (Glycine soja Sieb. et Zucc) population was measured using kinship coefficients and spatial autocorrelation coefficients to reveal fine-scale spatial patterns of genetic structure for guiding collection in ex situ conservation. • Individual families (100) of a single population were sampled in Jiangwan (Shanghai, China) and their specific locations mapped. Individual plants were genotyped for 331 ISSR loci from 15 selective ISSR primers; 45% were demonstrated to be polymorphic. • Pairwise kinship coefficients between individuals were calculated, and then regressed based on the spatial distance between individuals. The results indicated a close genetic relationship among individual families in the patch with a diameter of c. 30m. Spatial autocorrelation analysis suggested that there were significant clusters of genes within the population; c. 81.4% of the loci were found to be positively correlated in the first two distance classes (0-10m). • The results suggest, for conservation genetics, sampling within a wild soybean population should be conducted at 10 m intervals across the entire population to optimize the genetic diversity in collections taken from that population.

Are ecotone properties scale-dependent? A test from a Nothofagus treeline in southern New Zealand

Species richness, the location of exotic species and heterogeneity (investigated via dissimilarity and via species-area relations) were investigated in relation to spatial scale, in an ecotone between Nothofagus forest and sub-alpine shrubland. The rate of change in ordination score as well as tree diameter and the dripline were used to locate the position of the ecotone. Patterns of species richness were largely scale-independent, with species richness lowest in the forest community, intermediate in the ecotone, highest a short distance into the shrubland, and lower again in the shrubland further from the ecotone. High richness just into the shrubland is attributed to the existence of a fine-scale spatial mosaic pattern of vegetation, though the spatial mass effect may have a role. Exotic species were absent in the forest, but occurred sparsely in the ecotone and in the shrubland, possibly with decreasing frequency away from the ecotone. Community pattern, expressed by species-based dissimilarity and species-area curves, also differed. The ecotone community was the most heterogeneous (indicated by higher dissimilarity values and a steeper species-area slope with higher Arrhenius z-values), with the forest the least heterogeneous and the shrubland intermediate. We conclude that z-values are inter-woven with both habitat and spatial scale, and that this argues against a universal relationship between species and area.

Using dendrochronology to identify major ice storm events in oak forests of southwestern Virginia

Major ice storms are significant forest disturbance agents and natural hazards in east- ern North America. Studies of forest damage suggest that ice storm severity varies among topo- graphic positions, but little climatic information is available to evaluate fine-scale variations in ice storm climatology. Our study assesses the utility of tree-ring analysis for identifying fine-scale spatial patterns and long-term temporal variations in the frequency of major ice storms. We looked for ice storm signals in tree-ring chronologies of chestnut oak Quercus prinus L. and black oak Q. velutina Lam. at 2 sites in southwestern Virginia that were affected by known ice storms in 1979 and 1994. Radial growth of these species exhibits a dual response to ice storm disturbance. Trees with substan- tial canopy loss show reduced radial growth for several years following an ice storm. Other trees dis- play increased growth due to the loss of competitors. We identified thresholds of ring-width increase and decrease that distinguished ice storms from other events, permitting a preliminary attempt to reconstruct ice storm history at each of the 2 study sites. For our Gap Mountain site, ring-width chronologies spanning the period 1914-1998 record apparent signals of major ice storms in 1920, 1979, and 1994. For the Walker Mountain site, our results suggest that during the period 1901-1998 the stand was affected by major ice storms in 1918 and 1994. This study suggests that den- drochronology provides a promising method for understanding fine-scale spatial patterns of ice storm disturbance in hardwood forests.

The effect of grazing on the spatial heterogeneity of vegetation.

Grazing can alter the spatial heterogeneity of vegetation, influencing ecosystem processes and biodiversity. Our objective was to identify why grazing causes increases in the spatial heterogeneity of vegetation in some cases, but decreases in others. The immediate effect of grazing on heterogeneity depends on the interaction between the spatial pattern of grazing and the pre-existing spatial pattern of vegetation. Depending on the scale of observation and on the factors that determine animal distribution, grazing patterns may be stronger or weaker than vegetation patterns, or may mirror the spatial structure of vegetation. For each possible interaction between these patterns, we make a prediction about resulting changes in the spatial heterogeneity of vegetation. Case studies from the literature support our predictions, although ecosystems characterized by strong plant-soil interactions present important exceptions. While the processes by which grazing causes increases in heterogeneity are clear, how grazing leads to decreases in heterogeneity is less so. To explore how grazing can consistently dampen the fine-scale spatial patterns of competing plant species, we built a cell-based simulation model that features two competing plant species, different grazing patterns, and different sources of vegetation pattern. Only the simulations that included neighborhood interactions as a source of vegetation pattern produced results consistent with the predictions we derived from the literature review.

Reproductive performance links to fine-scale spatial patterns of female grey seal relatedness.

Fine-scale spatial patterns of female relatedness throughout the established grey seal breeding colony of North Rona, Scotland, were investigated by accurate mapping and spatially explicit analyses of a large sample (n = 262) of mothers using variation at nine microsatellite DNA loci. Local spatial autocorrelation analyses identified locations where seals were more highly related to the colony than average. These locations were also areas where the more successful females bred, were occupied first during each breeding season, were centrally placed locations of preferred habitat types and were likely to be the locations which were the first to be colonized historically. Mothers occupying such sites achieved higher than average pup growth rates, suggesting a founder fitness benefit.