Biology subjects

Ballare, K.

Publications and source records attributed to Ballare, K..

3 recordsLinked to original sources

bioRxiv2019

Scale-dependent effects of geography, host ecology, and host genetics on diversity of a stickleback parasite metacommunity

Many metacommunities are distributed across habitat patches that are themselves aggregated into groups. Perhaps the clearest example of this nested metacommunity structure comes from multi-species parasite assemblages, which occupy individual hosts that are aggregated into host populations. At both spatial scales, we expect parasite community diversity in a given patch (either individual host or population) to depend on patch characteristics that affect colonization rates and species sorting. But, are these patch effects consistent across spatial scales? Or, do different processes govern the distribution of parasite community diversity among individual hosts, versus among host patches? To answer these questions, we document the distribution of parasite richness among host individuals and among populations in a metapopulation of threespine stickleback (Gasterosteus aculeatus). We find some host traits (host size, gape width) are associated with increased parasite richness at both spatial scales. Other patch characteristics affect parasite richness only among individuals (sex), or among populations (lake size, lake area, elevation, and population mean heterozygosity). These results demonstrate that some rules governing parasite richness in this metacommunity are shared across scales, while others are scale-specific.

ecology↗

bioRxiv2019

The Goldilocks effect of lake size on within-population diversity in stickleback

Many generalist species consist of disparate specialized individuals, a phenomenon known as individual specialization. This within-population niche variation can stabilize population dynamics, reduce extinction risk, and alter community composition. But, we still only vaguely understand the ecological contexts that promote niche variation and its stabilizing effects. Adaptive dynamics models predict that intraspecific variation should be greater in environments with two or more equally-profitable resources, but reduced in environments dominated by one resource. Here, we confirm this prediction using a comparison of threespine stickleback in 33 lakes in on Vancouver Island, Canada. Stickleback consume a combination of benthic and limnetic invertebrates, focusing on the former in small lakes, the latter in large lakes. Intermediate-sized lakes support generalist populations, which arise via greater among-individual diet variation, not by greater individual diet breadth. These intermediate lakes exhibit correspondingly greater morphological diversity, while genomic diversity increases linearly with lake size. These results support the theoretical expectation that habitats with an intermediate ratio of resources are \"just right\" for promoting ecologically relevant intraspecific diversification.

ecology↗

bioRxiv2019

Scale-dependent effects of geography, host ecology, and host genetics, on species composition and co-occurrence in a stickleback parasite metacommunity

ABSTRACTA core goal of ecology is to understand the abiotic and biotic variables that regulate species distributions and community composition. A major obstacle is that the rules governing species distribution can change with spatial scale. Here, we illustrate this point using data from a spatially nested metacommunity of parasites infecting a metapopulation of threespine stickleback fish from 34 lakes on Vancouver Island, British Columbia. Parasite communities differ among host individuals within each host population and between host populations. The distribution of each parasite taxon depends, to varying degrees, on individual host traits (e.g., mass, diet) and on host population characteristics (e.g., lake size, mean diet). However, in most cases, a given parasite was regulated by different factors at the host-individual and host-population scales, contributing to scale-dependent patterns of parasite-species co-occurrence.

ecology↗