Responses of a specialist and a generalist seed predator to variation in their common resource

Östergård, Hannah; Hambäck, Peter A.; Ehrlén, Johan

doi:10.1111/j.1600-0706.2009.17540.x

Cited by 8 publications

(8 citation statements)

References 29 publications

(31 reference statements)

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“…Coexistence is, for example, made possible by variations in the spatial [10] and temporal [50] availability of the common resource. Our results show that when niche trade-offs are spread across multiple resource axes, the coexistence of generalist and specialist clownfish species is possible and likely to be sustainable over evolutionary times.…”

Section: Resultsmentioning

confidence: 99%

Host specialist clownfishes are environmental niche generalists

2014

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Why generalist and specialist species coexist in nature is a question that has interested evolutionary biologists for a long time. While the coexistence of specialists and generalists exploiting resources on a single ecological dimension has been theoretically and empirically explored, biological systems with multiple resource dimensions (e.g. trophic, ecological) are less well understood. Yet, such systems may provide an alternative to the classical theory of stable evolutionary coexistence of generalist and specialist species on a single resource dimension. We explore such systems and the potential tradeoffs between different resource dimensions in clownfishes. All species of this iconic clade are obligate mutualists with sea anemones yet show interspecific variation in anemone host specificity. Moreover, clownfishes developed variable environmental specialization across their distribution. In this study, we test for the existence of a relationship between host-specificity (number of anemones associated with a clownfish species) and environmental-specificity (expressed as the size of the ecological niche breadth across climatic gradients). We find a negative correlation between host range and environmental specificities in temperature, salinity and pH, probably indicating a trade-off between both types of specialization forcing species to specialize only in a single direction. Trade-offs in a multi-dimensional resource space could be a novel way of explaining the coexistence of generalist and specialists.

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Section: Resultsmentioning

confidence: 99%

Host specialist clownfishes are environmental niche generalists

2014

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“…Additionally, because of the greater density of resources, foragers can minimize the energetic costs of moving between patches to find food [ 1 ]. Many studies have looked for the existence of RCE in a variety of different consumer-resource systems with predators [ 4 ], herbivores [ 5 , 6 , 7 ], pollinators [ 8 , 9 ] and seed predators [ 10 ]. While theory suggests that foragers should distribute their foraging efforts in ways to maximize fitness [ 11 ], results from empirical studies are mixed.…”

Section: Introductionmentioning

confidence: 99%

Contrasting Foraging Patterns: Testing Resource-Concentration and Dilution Effects with Pollinators and Seed Predators

Wenninger

Kim

Spiesman

et al. 2016

Insects

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Resource concentration effects occur when high resource density patches attract and support more foragers than low density patches. In contrast, resource dilution effects can occur if high density patches support fewer consumers. In this study, we examined the foraging rates of pollinators and seed predators on two perennial plant species (Rudbeckia triloba and Verbena stricta) as functions of resource density. Specifically, we examined whether resource-dense patches (densities of flower and seeds on individual plants) resulted in greater visitation and seed removal rates, respectively. We also examined whether foraging rates were context-dependent by conducting the study in two sites that varied in resource densities. For pollinators, we found negative relationships between the density of flowers per plant and visitation rates, suggesting dilution effects. For seed predators, we found positive relationships consistent with concentration effects. Saturation effects and differences in foraging behaviors might explain the opposite relationships; most of the seed predators were ants (recruitment-based foragers), and pollinators were mostly solitary foragers. We also found that foraging rates were site-dependent, possibly due to site-level differences in resource abundance and consumer densities. These results suggest that these two plant species may benefit from producing as many flowers as possible, given high levels of pollination and low seed predation.

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“…It has, for instance, been shown that spatial changes in occurrence and phenology of the main and alternative host plants might influence the resource preference of herbivores (Nylin et al . ; Ostergard, Hamback & Ehrlen ). Such environmentally triggered behavioural modifications at the species or community level should be known for conservation strategies aimed at effective provision of resources (Haisfield et al .…”

Section: Introductionmentioning

confidence: 99%

Forest management and regional tree composition drive the host preference of saproxylic beetle communities

Müller

Wende

Strobl

et al. 2015

Journal of Applied Ecology

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Summary1. Among saproxylic beetles, many early colonizers prefer particular host species. Ranking of preferred hosts of local saproxylic beetle communities is critical for effective dead-wood management in forests, but is rarely done because experiments with numerous tree species are labour and cost intensive. 2. We analysed the host preference of local saproxylic beetle communities on logs of 13 tree species in relation to management (unmanaged and managed beech stands, conifer plantations on natural beech sites) in three regions of Germany during the most critical period for host specificity, that is the first two years after harvesting. Hosts were ranked quantitatively based on the ordinal ranking of hosts by single beetle species, which in turn was based on the variation in beetle abundance. First, we employed a Bradley-Terry model in which ranking was derived from paired comparisons of host trees. Then, a model-based recursive partitioning of the Bradley-Terry model tested whether host preference of beetle communities is affected by stand management, region and decay progress of dead wood. 3. Our results indicated that beetle communities overall avoided logs of Fraxinus, Pseudotsuga, Larix and Tilia, and Carpinus ranked highest in preference. Carpinus also ranked highest for communities of broadleaf specialists; Picea abies ranked highest for communities of conifer specialists. Model-based recursive partitioning revealed that ranking of local hosts in conifer stands differed from that of broadleaf stands, and that ranking of hosts in broadleaf stands differed between regions, but only in the first year for both. 4. Synthesis and applications. Early-colonizing saproxylic beetle communities vary locally in their choice of host trees. Therefore, forest managers should focus on the enrichment of dead wood of regional tree species and tree species of the local stand to successfully promote earlycolonizing beetle.

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Responses of a specialist and a generalist seed predator to variation in their common resource

Cited by 8 publications

References 29 publications

Host specialist clownfishes are environmental niche generalists

Host specialist clownfishes are environmental niche generalists

Contrasting Foraging Patterns: Testing Resource-Concentration and Dilution Effects with Pollinators and Seed Predators

Forest management and regional tree composition drive the host preference of saproxylic beetle communities

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