Andrew J. Beattie

Spatial scaling of microbial eukaryote diversity

Patterns in the spatial distribution of organisms provide important information about mechanisms that regulate the diversity of life and the complexity of ecosystems. Although microorganisms may comprise much of the Earths biodiversity and have critical roles in biogeochemistry and ecosystem functioning, little is known about their spatial diversification. Here we present quantitative estimates of microbial community turnover at local and regional scales using the largest spatially explicit microbial diversity data set available (> 106 sample pairs). Turnover rates were small across large geographical distances, of similar magnitude when measured within distinct habitats, and did not increase going from one vegetation type to another. The taxa–area relationship of these terrestrial microbial eukaryotes was relatively flat (slope z = 0.074) and consistent with those reported in aquatic habitats. This suggests that despite high local diversity, microorganisms may have only moderate regional diversity. We show how turnover patterns can be used to project taxa–area relationships up to whole continents. Taxa dissimilarities across continents and between them would strengthen these projections. Such data do not yet exist, but would be feasible to collect.

Designing a cost-effective invertebrate survey : A test of methods for rapid assessment of biodiversity

We investigated three procedures that may lead to rapid and accurate assessment of epigaeic arthropod biodiversity. They are: (1) the identification of taxa whose diversity is correlated with that of others: (2) the identification of times and methods of sampling that produce estimates of diversity representative of more intensive sampling; and (3) the use of morphospecies inventories generated by non-specialists. Ants, beetles, and spiders were sampled from four forest types, in three seasons, using two collecting methods: pitfall trapping and extraction from litter. Specimens were sorted by a non-specialist to morphospecies and by specialist taxonomists to species. Richness (α-diversity) and turnover (β-diversity) were compared for different sampling regimes using morphospecies and species inventories. We found no significant positive correlations between ant, beetle, and spider species richness but there was a strong negative correlation between ant and beetle richness. For beetles alone, richness within the families Carabidae, Scarabaeidae, and Pselaphidae (i.e, avoiding taxonomically problematic families) was significantly correlated with richness within all other families. Assessment of turnover revealed that: (1) the four forest types contained significantly different assemblages of ants and beetles but not spiders and 92) the four forests were less clearly discriminated using species from the three beetle families Carabidae, Scarabaeidae, and Pselaphidae when compared to species from all beetle families pooled. Analyses of single sampling periods and methods revealed that summer and spring pitfall samples were most representative of more intensive sampling. That is: (1) the richness of ants and beetles in these samples was significantly positively correlated with the richness of all other samples and 92) turnover of beetles and ants among the four forests revealed by summer pitfall samples was similar to turnover using all samples. The three beetle surrogate families recorded by pitfall samples in spring, and to a lesser extent summer, showed significant correlations in richness with all other beetle species recorded in the same samples. However, the assessment of turnover was less accurate when only surrogate families were used. The most accurate and cost-effective assessment of turnover was generated by a summer pitfall sample in which data for ants, carabid, and scarab beetles were combined and analyzed as a single data set. Results were largely consistent regardless of whether species or morphospecies were used, which suggests that monitoring and assessment of terrestrial invertebrate biodiversity may be achieved by the careful use of morphospecies. Our results also suggest those invertebrate taxa, sampling methods, and sampling periods that yield the most consistent and reliable assessment of epigaeic invertebrate biodiversity in Australian temperate hardwood forests. However, empirical studies that follow the protocols discussed in this paper are urgently required in different environments. These studies may point the way to more representative monitoring and assessment of terrestrial biodiversity.

The Guild of Myrmecochores in the Herbaceous Flora of West Virginia Forests

Analysis of herbaceous vegetation and ant activity in random quadrats from 10 forest sites in West Virginia, USA, shows that ant-dispersed (myrmecochorous) plant species constitute about 30% of the herbaceous flora. Twenty-one such species were encountered in this study, three of which were not previously known myrmecochores: Carexjamesii, C. laxiculmis and Luzula echin- ata. Ant activity is a good predictor of the number of myrmecochorous species at a given site. There is also a weak correlation between ant activity and overall herbaceous species richness. A matrix of correlation coefficients and Wisconsin ordination suggest that the ant-dispersed species constitute a guild. The number of species in a guild for a given site may be limited by competition for ant diaspore vectors, and/or germination microsites. These resources are likely to be especially critical for shade-adapted forest herbs which experience nutrient stress. The ant-diaspore mutualism is viewed as a strategy to overcome nutrient scarcity, and the present study shows clearly that it is a major factor in forest herbaceous communities.

Effects of Ant Mounds on Soil Chemistry and Vegetation Patterns in a Colorado Montane Meadow

The vegetation and soil chemistry of 15 abandoned mounds of Formica canadensis were compared to control quadrats in a meadow at 2900 m near Gothic, Colorado, USA. Principal Components Analysis indicated the mound vegetation was relatively homogeneous and distinct from nonmound vegetation. Discriminant Analysis indicated that mounds were characterized by Bromus polyanthus and Achillea millefolium, and nonmounds by Poa interior. A parallel analysis of 15 soil chemicals indicated some statistically significant chemical differences between mounds and nonmounds. Several micronutrients (Fe, Zn, Mn), were lower in mounds but were unlikely to be deficient. Ant—dispersed plants (myrmecochores) were almost entirely restricted to nonmound quadrats. See full-text article at JSTOR

Mutualisms: Assessing the benefits to hosts and visitors

A great number and variety of interactions are widely assumed to be mutualistic because the species involved exchange goods or services from which they appear to derive benefit. A familiar example is pollination, in which animal vectors receive food in the form of nectar and/or pollen, while the ovules of plants are fertilized. Unfortunately, most studies fail to demonstrate that both participants benefit in any significant way and therefore lack the information necessary to determine whether a given interaction is mutualistic. While mutualism is thought to be a common type of species interaction, there is still little evidence for this belief.

The nest chemistry of two seed-dispersing ant species

SummaryNests of Myrmica discontinua and Formica canadensis from meadows in the vicinity of the Rocky Mountain Biological Laboratory, Colorado, USA were analysed for fifteen plant macronutrients, micronutrients and heavy metals. Nest samples were compared with control samples taken from surrounding soils. Principal components analysis and discriminant function analysis show that the nest chemistry of F. canadensis differs significantly from that of M. discontinua. Also, nest chemistry differs from that of the surrounding soils. Both kinds of nests contain elevated levels of phosphorus relative to adjacent soils, but F. canadensis nests may be deficient in the micronutrients zinc, iron and manganese. On the other hand, the nests of M. discontinua are also richer in ammonium and percent organic matter. These results are discussed with respect to the hypothesis that relocation of ant-dispersed seeds into ant nests may be advantageous to the plant species involved. It is suggested the relocation to Myrmica nests, rich in phosphorus, potassium and nitrogen, may result in greater survivorship of seedlings.

Population consequences of changes in an ant-seed mutualism in Sanguinaria canadensis

SummarySeed dispersal by ants was studied in three populations of the myrmecochore, Sanguinaria canadensis, located in three habitats, each of which showed a different level of disturbance. Frequency of seed removal and the distances seeds were carried by ants were related to plant density, dispersion and the relative proportions of sexual and asexual reproduction in each population. Seeds in the least disturbed habitat were removed frequently and carried, by a wide variety of ants, distances of up to 12 m. Plant density was low and clone size was small. There was a relatively low level of sexual (seed) reproduction but seeds were generally transported well beyond the boundaries of the parent clones. By contrast, at the most disturbed site, plant density was high and clone size was very large. While there was a high level of seed production, seeds were rarely moved by ants and since removal distances were short, the probability of a seed being relocated beyond the limits of the parent clone was miniscule. The third population from a habitat which was intermediate in disturbance yielded data intermediate to the others. The data show that habitat disturbance, in disrupting the ant fauna and hence the ant-seed mutualism, has profound effects upon population density, dispersion and patterns of reproduction. Density-dependent regulation of sexual output predicted, for example, by the Strawberry-Coral model (Williams 1975), is maladaptive when the antseed mutualism is disturbed. We discuss the implications of this for theoretical modeling, the significance of mutualisms and the assessment of disturbance for conservation.

Effectiveness of Biodiversity Surrogates for Conservation Planning: Different Measures of Effectiveness Generate a Kaleidoscope of Variation

Conservation planners represent many aspects of biodiversity by using surrogates with spatial distributions readily observed or quantified, but tests of their effectiveness have produced varied and conflicting results. We identified four factors likely to have a strong influence on the apparent effectiveness of surrogates: (1) the choice of surrogate; (2) differences among study regions, which might be large and unquantified (3) the test method, that is, how effectiveness is quantified, and (4) the test features that the surrogates are intended to represent. Analysis of an unusually rich dataset enabled us, for the first time, to disentangle these factors and to compare their individual and interacting influences. Using two data-rich regions, we estimated effectiveness using five alternative methods: two forms of incidental representation, two forms of species accumulation index and irreplaceability correlation, to assess the performance of ‘forest ecosystems’ and ‘environmental units’ as surrogates for six groups of threatened species—the test features—mammals, birds, reptiles, frogs, plants and all of these combined. Four methods tested the effectiveness of the surrogates by selecting areas for conservation of the surrogates then estimating how effective those areas were at representing test features. One method measured the spatial match between conservation priorities for surrogates and test features. For methods that selected conservation areas, we measured effectiveness using two analytical approaches: (1) when representation targets for the surrogates were achieved (incidental representation), or (2) progressively as areas were selected (species accumulation index). We estimated the spatial correlation of conservation priorities using an index known as summed irreplaceability. In general, the effectiveness of surrogates for our taxa (mostly threatened species) was low, although environmental units tended to be more effective than forest ecosystems. The surrogates were most effective for plants and mammals and least effective for frogs and reptiles. The five testing methods differed in their rankings of effectiveness of the two surrogates in relation to different groups of test features. There were differences between study areas in terms of the effectiveness of surrogates for different test feature groups. Overall, the effectiveness of the surrogates was sensitive to all four factors. This indicates the need for caution in generalizing surrogacy tests.

Plant dispersion, pollination and gene flow in Viola

SummaryThe effect of pollinator activity on gene flow in colonies of Viola were examined by measuring pollinator flight distances, the frequency of interplant flights and percent pollination under different plant spacing patterns. Pollinator flight distances were directly proportional to spacing parameters while the frequency of interplant flights and percent pollination were inversely proportional to spacing parameters. These findings show that gene flow is reduced by pollinator activity over a wide range of spacing parameters but in populations with low spacing means highly localized gene exchange can occur within the colony. Isolation of colonies may be expected under these circumstaces and cleistogamy may be the optimal breeding system. However, chasmogamous flowers may be important both in promoting within-colony gene exchange and long distance between-colony gene exchange corresponding to the sexual functions proposed in several recent models. Viola colonies appear to be semi-isolated demes with pollinator service which can bring adaptive genes to high localized frequencies, but which maintains low frequency, long-distance gene dispersal. This pattern corresponds to the “Shifting Balance” view of evolution.

Land systems as surrogates for biodiversity in conservation planning

Environmental surrogates (land classes) for the distribution of biodiversity are increasingly being used for conservation planning. However, data that demonstrate coincident patterns in land classes and biodiversity are limited. We ask the overall question, “Are land systems effective surrogates for the spatial configuration of biodiversity for conservation planning?” and we address three specific questions: (1) Do different land systems represent different biological assemblages? (2) Do biological assemblages on the same land system remain similar with increasing geographic separation? and (3) Do biological assemblages on the same land system remain similar with increasing land system isolation? Vascular plants, invertebrates, and microbiota were surveyed from 24 sites in four land systems in arid northwest New South Wales, Australia. Within each land system, sites were located to give a hierarchy of inter-site distances, and land systems were classified as either “low isolation” (large and continuous) or “high isolation” (small patches interspersed among other land systems). Each type of land system supported components of biodiversity either not found, or found infrequently, on other land systems, suggesting that land systems function as surrogates for biodiversity, and that conservation-area networks representing land-system diversity will also represent biological diversity. However, the majority of taxa were found on more than one land-system type, suggesting that a large proportion of the plant, arthropod, and microbial biodiversity may be characterized by widespread species with low fidelity to particular land systems. Significant relationships between geographic distance among sites and differences among assemblages were revealed for all taxa except the microbiota. Therefore, as sites on the same land system were located farther apart, the assemblages at those sites became more different. This finding strongly suggests that conservation planning based on land-system diversity should also sample the geographic range occupied by each land system. Land-system isolation was not revealed to be a significant source of variation in assemblage composition. Our research finds support for environmental surrogates for biodiversity in conservation planning, specifically the use of land systems and similarly derived land classifications. However, the need for explicit modeling of geographic distance in conservation planning is clearly indicated.