Wolverine Conservation and Management

ABSTRACT This Special Section includes 8 peer-reviewed papers on the wolverine (Gulo gulo) in southern North America. These papers provide new information on current and historical distribution, habitat relations at multiple spatial scales, and interactions with humans. In aggregate, these papers substantially increase our knowledge of wolverine ecology and population dynamics in North America, in many cases replacing previous speculations and informed judgments with empirical information. North American wolverines occur primarily in tundra, taiga, and subalpine environments. These environments become increasingly fragmented at southern latitudes, where wolverine populations occur at low densities and are potentially vulnerable to human-caused mortality. The combination of highly fragmented habitat, demographic sensitivity to adult mortality, and low population densities make local wolverine populations difficult to monitor and easy to overharvest. Where populations are fragmented, persistence is critically dependent on dispersal between habitat islands. Although dispersal dynamics are poorly understood, high levels of genetic structure observed in both current and historical populations indicate that dispersal between mountain ranges is limited. Wolverine biology remains poorly understood, and many fundamental issues need additional research.     

The biogeography of species,with special reference to ferns

An important element of the biogeography of species is the geographic aspects of speciation. The geography of species has a role in the processes of speciation which have a reciprocal role in species geography. The homosporous ferns provide an especially favorable group for biogeographic studies because nearly all species have an equivalent capacity for dispersal and migration. Species ranges are based on the ecology of the environment, rather than on animal vectors of dispersal or pollination. However, with allowance for these differences, the processes of geographic speciation are basically the same in ferns and other vascular plants, although often on a broader geographic scale in the ferns. Speciation most frequently produces a new species with a small range, which can rapidly expand to occupy the geography of the environment to which the species is adapted. The members of a closely related speciesgroup retain their morphological and geographic relations for a relatively short time. With speciation, changes in distribution, and extinction, the original relations of the species and the biogeographical history of the group will be lost. High regional species diversity occurs in the wet mountainous regions of the tropics, where there is greatest ecological diversity and maximal opportunities for speciation and persistence.     

Functional connectivity in replicated urban landscapes in the land snail (Cornu aspersum)

Urban areas are highly fragmented and thereby exert strong constraints on individual dispersal. Despite this, some species manage to persist in urban areas, such as the garden snail, Cornu aspersum, which is common in cityscapes despite its low mobility. Using landscape genetic approaches, we combined study area replication and multiscale analysis to determine how landscape composition, configuration and connectivity influence snail dispersal across urban areas. At the overall landscape scale, areas with a high percentage of roads decreased genetic differentiation between populations. At the population scale, genetic differentiation was positively linked with building surface, the proportion of borders where wooded patches and roads appeared side by side and the proportion of borders combining wooded patches and other impervious areas. Analyses based on pairwise genetic distances validated the isolation‐by‐distance and isolation‐by‐resistance models for this land snail, with an equal fit to least‐cost paths and circuit‐theory‐based models. Each of the 12 landscapes analysed separately yielded specific relations to environmental features, whereas analyses integrating all replicates highlighted general common effects. Our results suggest that urban transport infrastructures facilitate passive snail dispersal. At a local scale, corresponding to active dispersal, unfavourable habitats (wooded and impervious areas) isolate populations. This work upholds the use of replicated landscapes to increase the generalizability of landscape genetics results and shows how multiscale analyses provide insight into scale‐dependent processes.     

Increases in air temperature can promote wind-driven dispersal and spread of plants

Long-distance dispersal (LDD) of seeds and pollen shapes the spatial dynamics of plant genotypes, populations and communities. Quantifying LDD is thus important for predicting the future dynamics of plants exposed to environmental changes. However, environmental changes can also alter the behaviour of LDD vectors: for instance, increasing air temperature may enhance atmospheric instability, thereby altering the turbulent airflow that transports seed and pollen. Here, we investigate temperature effects on wind dispersal in a boreal forest using a 10-year time series of micrometeorological measurements and a Lagrangian stochastic model for particle transport. For a wide range of dispersal and life history types, we found positive relations between air temperature and LDD. This translates into a largely consistent positive effect of +3°C warming on predicted LDD frequencies and spread rates of plants. Relative increases in LDD frequency tend to be higher for heavy-seeded plants, whereas absolute increases in LDD and spread rates are higher for light-seeded plants for which wind is often an important dispersal vector. While these predicted increases are not sufficient to compensate forecasted range losses and environmental changes can alter plant spread in various ways, our results generally suggest that warming can promote wind-driven movements of plant genotypes and populations in boreal forests.     

An evolutionary model of female dominance relations in primates

Though a few authors have provided individual selection explanations for the existence of dominance hierarchies, no unitary functional model exists which is capable of accounting for specific forms of dominance hierarchies. The framework of a model of female dominance relations in primates is developed and should be applicable to other species exhibiting overlapping generations, iteroparity, low female dispersal, and high parental investment. This model is based on the principles of individual selection, kin selection, reproductive value, and evolutionarily stable strategies. Three functional hypothesis are presented concerning female dominance relations. These hypotheses are tested using life table data for Macaca mulatta. Sister-sister, mother-daughter, and other rank relations are analyzed in detail taking into account self interest, conflicts of interest, and the interest of supporters in rank relations. One of the hypothesis satisfactorily accounts for the principal elements of the female dominance hierarchy in Macaca mulatta.     

How does intraspecific density regulation influence metapopulation synchrony and persistence?

Intraspecific density regulation influences the synchronization of local population dynamics through dispersal. Spatial synchrony in turn may jeopardize metapopulation persistence. Joining results from previous studies suggests that spatial synchrony is highest at moderate over-compensation and is low at compensating and at very strong over-compensating density regulation. We scrutinize this supposition of a unimodal relationship using a process-based metapopulation model with explicit local population dynamics. We extend the usually studied range of density regulation to under-compensation and analyse resulting metapopulation persistence. We find peaks of spatial synchrony not only at over-compensatory but also under-compensatory density regulation and show that effects of local density compensation on synchrony follow a bimodal rather than unimodal relationship. Persistence of metapopulations however, shows a unimodal relationship with a broad plateau of high persistence from compensatory to over-compensatory density regulation. This range of high persistence comprises both levels of low and high spatial synchrony. Thus, not synchrony alone jeopardizes metapopulation persistence, but only in interplay with high local extinction risk. The functional forms of the relations of density compensation with spatial synchrony and persistence are robust to increases in dispersal mortality, landscape dynamics, or density dependence of dispersal. However, with each of these increases the maxima of spatial synchrony and persistence shift to higher over-compensation and levels of synchrony are reduced. Overall, for over-compensation high landscape connectivity has negative effects while for under-compensation connectivity affects persistence positively. This emphasizes the importance of species life-history traits for management decisions with regard to landscape connectivity: while dispersal corridors are essential for species with under-compensatory density regulation, they may have detrimental effects for endangered species with over-compensation.     

小型哺乳动物亲缘关系对其种群动态的作用

主要综述小型哺乳动物亲缘关系对其种群动态的作用及其研究进展。与非亲缘个体比较, 亲缘个体间的相互作用趋于亲密、巢区共享程度高, 亲缘关系水平对扩散有明显的作用。亲缘关系水平的差异可改变种群增长速率及种群统计学特征, 对提高雌体存活率、后代断乳成功率、后代存活率及性比具有显著的作用。亲缘关系的分子生态学研究主要集中于亲权鉴定和种群遗传结构的分析。     

Neighborhood models of plant population dynamics 3. Models with spatial heterogeneity in the physical environment

Population dynamic models are developed for communities of annual plants in spatially heterogeneous environments. These models are constructed from submodels of the survivorship, fecundity, germination, and dispersal of individual plants. The submodels include the effects of spatially local interactions on plant performance and the spatial variation in performance caused by spatial heterogeneity in the physical environment. It is possible to estimate the submodels from data on experimental communities in either the field or greenhouse and so it is possible to empirically calibrate the population dynamic models developed. Each population dynamic model explicitly includes the spatial distribution of individuals in a plant community.Several two-species models for plants in patchy environments are studied to examine the community-level consequences of spatial heterogeneity in the physical environment. The results fall into two classes. First, community structure is in part determined by a relation between patch size and mean seed dispersal distance. Specifically, coexistence is, in some cases, possible only if patches are sufficiently larger than the mean dispersal distance. Second, community structure is also affected by relations between patch size and the maximum distance over which two plants interact (termed the neighborhood radius). In some cases, coexistence is possible only if patch size is sufficiently larger than the neighborhood radius. In others, the species coexist only if patch size is sufficiently smaller than the neighborhood radius. In still other cases, coexistence is possible only if patch sizes are within critical bounds, where the sizes of the critical bounds are in units of the neighborhood radius. All results involving relations between the neighborhood radius and patch size are direct consequences of the sedentary nature of plants and the fact that individual plants interact primarily with nearby plants.     

Connectivity and cladoceran species richness in a metacommunity of shallow lakes

SUMMARY 1. The shallow ponds of the nature reserve 'De Maten' form a metacommunity, in which individual ponds are highly interconnected via a system of overflows and rivulets. This study reports on the relations between cladoceran species richness and (a) connectivity patterns and (b) local environmental variables.
2. No relation was found between local species richness and three connectivity variables or dispersal pathways.
3. Spatial configuration was related to richness, but was confounded by environmental variables for 2 of 3 years. In those 2 years, there was a significant linear relation between Secchi disc depth and species richness, suggesting an important impact of the clearwater/turbid state alternative equilibria in shallow lakes in determining cladoceran richness. Only in the year in which environmental variables were unimportant did connectivity between the ponds influence species richness.
4. These results suggest that local environmental variables related to the clearwater/turbid state alternative equilibria in shallow lakes are important in determining cladoceran species richness. Connectivity and dispersal of individuals between the different ponds only act secondarily by increasing the general species richness within a pond through dispersal from ponds with different environmental conditions.     

外来种入侵的生物学与生态学基础的若干问题

外来物种的入侵及其所造成的危害已越来越为人们所认识。一个外来物种入侵一个新的生境无疑要具备一定的条件 ,尽管目前对这种条件的研究还只是初步的。首先从其自身来说 ,需要有足够的入侵性 ,这可以认为是入侵种的生物学基础 ,可能表现为具有多倍性、一定的遗传变异、杂合性或表型可塑性 ,以及不同的交配系统等 ;其次一个物种的入侵成功还取决于入侵生境的可入侵性 ,这可以认为是入侵种的生态学基础 ,而新的种间关系的形成 ,尤其是入侵种与其他种类的互惠共生关系的建成是关键。本文主要介绍了有关入侵种的生物学和生态学基础中的一些最新进展 ,希望有助于我国学者对相关研究内容的开展以及对有害外来种入侵的防治     

The effect of spatial pattern on community dynamics; a comparison of simulated and field data

The effect of the spatial limits of dispersal and competition on plant community dynamics was studied using Monte-Carlo simulation. The model generates community point patterns, using life-table data, dispersion parameters and radii of competitive effects. These data have been estimated in a field situation, for the 11 most abundant weed species growing on the refuse soil dumps of a strip coal mine. In a simulation experiment, the patterns produced by two versions of the model were compared. The first was based on the field situation as much as possible; the other used the same input parameters except for dispersal, which was randomized in this case. We found considerable differences regarding the temporal changes of species abundances, the realized competitive abilities and the spatial patterns generated by the two versions. An important conclusion of this comparison is that the realized competitive effect (both intra-and interspecific) of a species is dependent not only on constant competition parameters, but on the abundance relations and on the spatial patterns of the competing populations as well. It is concluded that the spatial limits of dispersal and competition may result in the increased persistence of weak competitors, moderate the realized competitive effects of strong species, and shape the spatial coalition structure of the community.     

Environmental and dispersal controls of an annual plant’s distribution: how similar are patterns and apparent processes at two spatial scales?

At scales from microsites to entire ranges, species’ distributions reflect limited adaptation and/or limited dispersal. To what extent are specific distribution patterns and processes similar across scales? We investigated environmental effects—presumed because of adaptation—and independent spatial effects—presumed because of dispersal—on distribution at two scales (landscape patches of approximately 1,300 m², sampled along transects, and 4-m² cells, sampled in contiguous grids within populations) and on individual performance (water status, reproduction) in the California annual, Clarkia xantiana ssp. xantiana. Because water limitation helps set this species’ regional borders, we expected occupancy and performance at smaller scales to correlate with topographic and soil features affecting water relations. At the patch scale, environmental features associated with reduced water stress (i.e., steep slopes that face north; coarse, soft soils; igneous rather than metasedimentary parent rock) predicted occupancy. Spatial aggregation was not detected, but incomplete occupancy of apparently suitable patches indicated that dispersal limits occupancy. At the scale of small cells, relationships between environmental variables, occupancy, density, and performance varied among populations. Associations sometimes resembled those at the patch scale but sometimes opposed them. Spatial aggregation in cell occupancy and/or density occurred in all populations, implying limited dispersal, whereas spatial aggregation of water potential values in some populations might have arisen from spatially structured unmeasured environmental variables. Limited adaptation to drought and limited patch colonization appear to affect patch occupancy in C. xantiana ssp. xantiana, whereas smaller-scale patterns indicate consistent effects of limited dispersal and somewhat variable environmental effects.     

Social Play in the Domestic Cat

The social play of domestic cats in the laboratory and at homewas examined. Categories and sequences of motor patterns wereidentified and analyzed. The developmental period during whichsocial play was most frequent was established to be from 4 weeksto 4 months. The results suggest that social play functionsto provide specific forms of exercise and as a means of developingand maintaining social relations among littermates. The declinein social play appears to be related to dispersal of the youngand to a decrease in preference for social contact.     

The consequences of clone size for paternal and maternal success in domestic apple (Malus x domestica)

Clonal growth in plants can increase pollen and ovule production per genet. However, paternal and maternal reproductive success may not increase because within-clone pollination (geitonogamy) can reduce pollen export to adjacent clones (pollen discounting) and pollen import to the central ramets (pollen limitation). The relationship between clone size and mating success was investigated using clones of Malus × domestica at four orchards (blocks of 1-5 rows of trees). For each block, maternal function was measured as fruit and seed set in all rows and paternal function as siring rate estimated from isozyme profiles in the first row of the adjacent block. Expected relations between reproductive success and clone size were generated from simulations and data on pollen dispersal in this species. Siring rate per clone averaged 70% and did not increase significantly with block size, consistent with simulations of pollen dispersal under pollen discounting. Simulations also indicated that the ratio of compatible to incompatible pollen received by a tree should decline with increased block size and from the periphery to the center of blocks. However, female function was not significantly reduced among block sizes or within blocks. The results suggest that paternal function may be more sensitive to the effects of clonality than female function.     

Evolution of dispersal polymorphism and local adaptation of dispersal distance in spatially structured landscapes

Many organisms show polymorphism in dispersal distance strategies. This variation is particularly ecological relevant if it encompasses a functional separation of short‐ (SDD) and long‐distance dispersal (LDD). It remains, however, an open question whether both parts of the dispersal kernel are similarly affected by landscape related selection pressures. We implemented an individual‐based model to analyze the evolution of dispersal traits in fractal landscapes that vary in the proportion of habitat and its spatial configuration. Individuals are parthenogenetic with dispersal distance determined by two alleles on each individual's genome: one allele coding for the probability of global dispersal and one allele coding for the variance σ of a Gaussian local dispersal with mean value zero. Simulations show that mean distances of local dispersal and the probability of global dispersal, increase with increasing habitat availability, but that changes in the habitat's spatial autocorrelation impose opposing selective pressure: local dispersal distances decrease and global dispersal probabilities increase with decreasing spatial autocorrelation of the available habitat. Local adaptation of local dispersal distance emerges in landscapes with less than 70% of clumped habitat. These results demonstrate that long and short distance dispersal evolve separately according to different properties of the landscape. The landscape structure may consequently largely affect the evolution of dispersal distance strategies and the level of dispersal polymorphism.     

The evolution of dispersal distance in spatially-structured populations

Most evolutionary models of dispersal have concentrated on dispersal rate, with emigration being either global or restricted to nearest neighbours. Yet most organisms fall into an intermediate region where most dispersal is local but there is a wide range of dispersal distances. We use an individual-based model with 2500 patches each with identical local dynamics and show that the dispersal distance is under selection pressure. The dispersal distance that evolves is critically dependent on the ecological dynamics. When the cost of dispersal increases linearly with distance, selection is for short-distance dispersal under stable and damped local dynamics but longer distance dispersal is favoured as local dynamics become more complex. For the cases of stable, damped and periodic patch dynamics global patch synchrony occurs even with very short-distance dispersal. Increasing the scale of dispersal for chaotic local dynamics increases the scale of synchrony but global synchrony does not neccesarily occur. We discuss these results in the light of other possible causes of dispersal and argue for the importance of incorporating non-equilibrium population dynamics into evolutionary models of dispersal distance.     

Platyhelminths as paleogeographical indicators

Turbellarians do not feature as examples in the present discussions on the theory and method of analytical biogeography. It is argued, however, that turbellarian distributional records form good examples of large-scale biogeographic patterns resulting from continental breakup. Some turbellarian taxa also indicate biogeographic links across the Pacific Ocean, which can be visualized readily by means of track construction. Amphi-pacific organismal distributions form the ingredients of trans-Pacific biogeographic tracks. Such tracks may be explained historically either as the result of dispersal or of vicariance. In the case of the flatworm examples, as well as many other organisms, dispersal explanations are the least satisfactory. However, under a vicariance paradigm the classical pre-drift reconstruction of Pangea cannot adequately explain trans-Pacific tracks. Therefore, alternative paleogeographic models may be invoked as explanatory hypotheses: the lost continent Pacifica, island integration, a new reconstruction of eastern Gondwanaland, an expanding earth. None of these alternative models is fully compatible with all geological and biogeographic data available at present. It is stressed that biogeographic data and theories should not be made subservient to geological theories. Biogeographical data on flatworms may indicate paleogeographical relations which are worthy of examination by geologists.     

Evolution of body condition‐dependent dispersal in metapopulations

Body condition‐dependent dispersal strategies are common in nature. Although it is obvious that environmental constraints may induce a positive relationship between body condition and dispersal, it is not clear whether positive body conditional dispersal strategies may evolve as a strategy in metapopulations. We have developed an individual‐based simulation model to investigate how body condition–dispersal reaction norms evolve in metapopulations that are characterized by different levels of environmental stochasticity and dispersal mortality. In the model, body condition is related to fecundity and determined either by environmental conditions during juvenile development (adult dispersal) or by those experienced by the mother (natal dispersal). Evolutionarily stable reaction norms strongly depend on metapopulation conditions: positive body condition dependency of dispersal evolved in metapopulation conditions with low levels of dispersal mortality and high levels of environmental stochasticity. Negative body condition‐dependent dispersal evolved in metapopulations with high dispersal mortality and low environmental stochasticity. The latter strategy is responsible for higher dispersal rates under kin competition when dispersal decisions are based on body condition reached at the adult life stage. The evolution of both positive and negative body condition‐dependent dispersal strategies is consequently likely in metapopulations and depends on the prevalent environmental conditions.     

Dispersal strategies, few dominating or many coexisting: the effect of environmental spatial structure and multiple sources of mortality

Interspecific competition, life history traits, environmental heterogeneity and spatial structure as well as disturbance are known to impact the successful dispersal strategies in metacommunities. However, studies on the direction of impact of those factors on dispersal have yielded contradictory results and often considered only few competing dispersal strategies at the same time. We used a unifying modeling approach to contrast the combined effects of species traits (adult survival, specialization), environmental heterogeneity and structure (spatial autocorrelation, habitat availability) and disturbance on the selected, maintained and coexisting dispersal strategies in heterogeneous metacommunities. Using a negative exponential dispersal kernel, we allowed for variation of both species dispersal distance and dispersal rate. We showed that strong disturbance promotes species with high dispersal abilities, while low local adult survival and habitat availability select against them. Spatial autocorrelation favors species with higher dispersal ability when adult survival and disturbance rate are low, and selects against them in the opposite situation. Interestingly, several dispersal strategies coexist when disturbance and adult survival act in opposition, as for example when strong disturbance regime favors species with high dispersal abilities while low adult survival selects species with low dispersal. Our results unify apparently contradictory previous results and demonstrate that spatial structure, disturbance and adult survival determine the success and diversity of coexisting dispersal strategies in competing metacommunities.