Intraspecific body size increases with habitat fragmentation in wild bee pollinators

Warzecha, Daniela; Diekötter, Tim; Wolters, Volkmar; Jauker, Frank

doi:10.1007/s10980-016-0349-y

Cited by 95 publications

(92 citation statements)

References 34 publications

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“…However, experimental research has illustrated that habitat fragmentation can have a variable effect on consumer body size within a population or community (e.g., Braschler & Baur, 2016;Davies et al, 2000;Sumner, Moritz, & Shine, 1999). Studies reporting a positive effect contributed this to the positive dependence of mobility on body size (Braschler & Baur, 2016;Jauker et al, 2016;Warzecha et al, 2016). With decreasing growth speed of the resource, the positive effect of isolation on consumer body size is amplified.…”

Section: Isolation and Resource Growth Effects On Consumer Body Sizmentioning

confidence: 99%

“…Large individuals and species, on the other hand, are capable of crossing unsuitable matrix to reach new patches and have higher tolerances to starvation (Davies, Margules, & Lawrence, 2000;Peters, 1983;Tscharntke & Brandl, 2004). This could explain why, although many empirical studies have investigated the effect of habitat fragmentation on body size distributions, a conclusive pattern remains elusive (e.g., Davies et al, 2000;Hamback et al, 2007;Jauker, Speckmann, & Wolters, 2016;Renauld, Hutchinson, Loeb, Poveda, & Connelly, 2016;Warzecha, Diekötter, Wolters, & Jauker, 2016). It thus remains difficult to predict how the spatial distribution of resources affects body size distributions.…”

Section: Introductionmentioning

confidence: 99%

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Size‐dependent movement explains why bigger is better in fragmented landscapes

Hillaert

Hovestadt

Vandegehuchte

et al. 2018

Ecology and Evolution

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Body size is a fundamental trait known to allometrically scale with metabolic rate and therefore a key determinant of individual development, life history, and consequently fitness. In spatially structured environments, movement is an equally important driver of fitness. Because movement is tightly coupled with body size, we expect habitat fragmentation to induce a strong selection pressure on size variation across and within species. Changes in body size distributions are then, in turn, expected to alter food web dynamics. However, no consensus has been reached on how spatial isolation and resource growth affect consumer body size distributions. Our aim was to investigate how these two factors shape the body size distribution of consumers under scenarios of size‐dependent and size‐independent consumer movement by applying a mechanistic, individual‐based resource–consumer model. We also assessed the consequences of altered body size distributions for important ecosystem traits such as resource abundance and consumer stability. Finally, we determined those factors that explain most variation in size distributions. We demonstrate that decreasing connectivity and resource growth select for communities (or populations) consisting of larger species (or individuals) due to strong selection for the ability to move over longer distances if the movement is size‐dependent. When including size‐dependent movement, intermediate levels of connectivity result in increases in local size diversity. Due to this elevated functional diversity, resource uptake is maximized at the metapopulation or metacommunity level. At these intermediate levels of connectivity, size‐dependent movement explains most of the observed variation in size distributions. Interestingly, local and spatial stability of consumer biomass is lowest when isolation and resource growth are high. Finally, we highlight that size‐dependent movement is of vital importance for the survival of populations or communities within highly fragmented landscapes. Our results demonstrate that considering size‐dependent movement is essential to understand how habitat fragmentation and resource growth shape body size distributions—and the resulting metapopulation or metacommunity dynamics—of consumers.

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Section: Isolation and Resource Growth Effects On Consumer Body Sizmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Size‐dependent movement explains why bigger is better in fragmented landscapes

Hillaert

Hovestadt

Vandegehuchte

et al. 2018

Ecology and Evolution

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“…A loss of traits often reflects the response of local communities to environmental change (‘response traits’, Lavorel & Garnier ) and can affect ecosystem functions (‘effect traits’, Lavorel & Garnier ) via changes in trait composition (Mlambo ; Warzecha et al . ). Trait‐based studies therefore offer a unique framework to understand mechanisms through which land‐use change and intensification affects biodiversity and potentially alters associated ecosystem functions (Verberk, Van Noordwijk & Hildrew ; Fournier et al .…”

Section: Introductionmentioning

confidence: 97%

Land‐use type and intensity differentially filter traits in above‐ and below‐ground arthropod communities

Birkhofer

Goßner

Diekötter

et al. 2017

Journal of Animal Ecology

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Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Below-ground arthropods are assumed to be less sensitive to such effects than above-ground arthropods. Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and above-ground arthropod communities. We used data on 722 arthropod species living above-ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae). Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands. Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and below-ground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats.

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“…Furthermore, size predicts which flowers individual bee species prefer and affects fruit production (48). Adult body size variation responds to environmental conditions (49,50), but the developmental mechanisms that are responsible for body size variation in bees are poorly described. Understanding the developmental mechanisms shaping size variation in these particular insects will deepen our understanding of their pollination abilities and population dynamics.…”

Section: Significancementioning

confidence: 99%

Metamorphosis is induced by food absence rather than a critical weight in the solitary bee,Osmia lignaria

Helm

Rinehart

Yocum

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Body size is an important phenotypic trait that correlates with performance and fitness. For determinate growing insects, body size variation is determined by growth rate and the mechanisms that stop growth at the end of juvenile growth. Endocrine mechanisms regulate growth cessation, and their relative timing along development shapes phenotypic variation in body size and development time. Larval insects are generally hypothesized to initiate metamorphosis once they attain a critical weight. However, the mechanisms underlying the critical weight have not been resolved even for well-studied insect species. More importantly, critical weights may or may not be generalizable across species. In this study, we characterized the developmental aspects of size regulation in the solitary bee, Osmia lignaria. We demonstrate that starvation cues metamorphosis in O. lignaria and that a critical weight does not exist in this species. Larvae initiated pupation <24 h after food was absent. However, even larvae fed ad libitum eventually underwent metamorphosis, suggesting that some secondary mechanism regulates metamorphosis when provisions are not completely consumed. We show that metamorphosis could be induced by precocene treatment in the presence of food, which suggests that this decision is regulated through juvenile hormone signaling. Removing food at different larval masses produced a 10-fold difference in mass between smallest and largest adults. We discuss the implications of body size variation for insect species that are provided with a fixed quantity of provisions, including many bees which have economic value as pollinators. insect body size model | critical weight | solitary bees | body size | pollinator B ody size is one of the most striking aspects of variation that occurs both within and among different species. Size correlates with performance and fitness, and their relationships are of central importance in life history theory (1), metabolic theory (2, 3), bioenergetics (4, 5), and ecological and evolutionary physiology (6, 7). For this reason, the developmental basis of size variation is of growing interest, especially common elements that cut across taxa (8). Theoretical and conceptual life history models have hypothesized that developmental thresholds shape patterns of adult size variation (9, 10), and the idea of a sizedependent basis of maturation is pervasive (9, 11).The insect body size model integrates genetic, tissue signaling, and hormonal elements that regulate the developmental basis of adult size variation (12). In tandem with increasingly detailed identification and characterization of mechanisms shaping body size (12-15), there has been an effort to simplify this complexity for the purposes of generalization and predictability (8,16). Three factors contribute to adult body size and serve as proxies for the endocrine regulation of metamorphosis: larval growth rate, the critical weight that induces metamorphosis, and the interval between the critical weight and cessation of growth (8,(16)(17)(18)(...

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Intraspecific body size increases with habitat fragmentation in wild bee pollinators

Cited by 95 publications

References 34 publications

Size‐dependent movement explains why bigger is better in fragmented landscapes

Size‐dependent movement explains why bigger is better in fragmented landscapes

Land‐use type and intensity differentially filter traits in above‐ and below‐ground arthropod communities

Metamorphosis is induced by food absence rather than a critical weight in the solitary bee,Osmia lignaria

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