Environmental heterogeneity and biotic interactions as potential drivers of spatial patterning of shorebird nests

2017 ◽  
Vol 32 (8) ◽  
pp. 1689-1703 ◽  
Author(s):  
Rose J. Swift ◽  
Amanda D. Rodewald ◽  
Nathan R. Senner
2018 ◽  
Author(s):  
Molly F Jenkins ◽  
Ethan P White ◽  
Allen H Hurlbert

Ecological communities are composed of a combination of core species that maintain local viable populations and transient species that occur infrequently due to dispersal from surrounding regions. Preliminary work indicates that while core and transient species are both commonly observed in community surveys of a wide range of taxonomic groups, their relative prevalence varies substantially from one community to another depending upon the spatial scale at which the community was characterized and its environmental context. We used a geographically extensive dataset of 968 bird community time series to quantitatively describe how the proportion of core species in a community varies with spatial scale and environmental heterogeneity. We found that the proportion of core species in an assemblage increased with spatial scale in a positive decelerating fashion with a concomitant decrease in the proportion of transient species. Variation in the shape of this scaling relationship between sites was related to regional environmental heterogeneity, with lower proportions of core species at a given scale associated with high environmental heterogeneity. This influence of scale and environmental heterogeneity on the proportion of core species may help resolve discrepancies between studies of biotic interactions, resource availability, and mass effects conducted at different scales, because the importance of these and other ecological processes are expected to differ substantially between core and transient species.


2019 ◽  
Author(s):  
Anna L. Hargreaves ◽  
Rachel M. Germain ◽  
Megan Bontrager ◽  
Joshua Persi ◽  
Amy L. Angert

AbstractLocal adaptation to broad-scale environmental heterogeneity can increase species’ distributions and diversification, but which environmental components commonly drive local adaptation— particularly the importance of biotic interactions—is unclear. Biotic interactions should drive local adaptation when they impose consistent divergent selection; if this is common we expect experiments to detect more frequent and stronger local adaptation when biotic interactions are left intact. We tested this hypothesis using a meta-analysis of common-garden experiments from 138 studies (149 taxa). Across studies, local adaptation was common and biotic interactions affected fitness. Nevertheless, local adaptation was neither more common nor stronger when biotic interactions were left intact, either between experimental treatments within studies (control vs. biotic interactions experimentally manipulated) or between studies that used natural vs. biotically-altered transplant environments. However, tropical studies, which comprised only 7% of our data, found strong local adaptation in intact environments but not when negative biotic interactions were ameliorated, suggesting that interactions frequently drive local adaptation in the tropics. Our results suggest that biotic interactions often fail to drive local adaptation even though they affect fitness, perhaps because the temperate-zone biotic environment is less predictable at the spatiotemporal scales required for local adaptation.


2017 ◽  
Author(s):  
Jan Toman ◽  
Jaroslav Flegr

AbstractEcological theories of sexual reproduction assume that sexuality is advantageous in certain conditions, for example, in biotically or abiotically more heterogeneous environments. Such theories thus could be tested by comparative studies. However, the published results of these studies are rather unconvincing. Here we present the results of a new comparative study based solely on the ancient asexual clades. The association with biotically or abiotically homogeneous environments in these asexual clades was compared with the same association in their sister, or closely related, sexual clades. Using the conservative definition of ancient asexuals (i.e. age > 1 million years), we found six pairs for which relevant ecological data are available. The difference between the homogeneity type of environment associated with the sexual and asexual species was then compared in an exact binomial test. Based on available literature, the results showed that the vast majority of ancient asexual clades tend to be associated with biotically or abiotically, biotically, and abiotically more homogeneous environments than their sexual controls. In the exploratory part of the study, we found that the ancient asexuals often have durable resting stages, enabling life in subjectively homogeneous environments, live in the absence of intense biotic interactions, and are very often sedentary, inhabiting benthos and soil. The consequences of these findings for the ecological theories of sexual reproduction are discussed.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6019 ◽  
Author(s):  
Molly F. Jenkins ◽  
Ethan P. White ◽  
Allen H. Hurlbert

Ecological communities are composed of a combination of core species that maintain local viable populations and transient species that occur infrequently due to dispersal from surrounding regions. Preliminary work indicates that while core and transient species are both commonly observed in community surveys of a wide range of taxonomic groups, their relative prevalence varies substantially from one community to another depending upon the spatial scale at which the community was characterized and its environmental context. We used a geographically extensive dataset of 968 bird community time series to quantitatively describe how the proportion of core species in a community varies with spatial scale and environmental heterogeneity. We found that the proportion of core species in an assemblage increased with spatial scale in a positive decelerating fashion with a concomitant decrease in the proportion of transient species. Variation in the shape of this scaling relationship between sites was related to regional environmental heterogeneity, with lower proportions of core species at a given scale associated with high environmental heterogeneity. Understanding this influence of scale and environmental heterogeneity on the proportion of core species may help resolve discrepancies between studies of biotic interactions, resource availability, and mass effects conducted at different scales, because the importance of these and other ecological processes are expected to differ substantially between core and transient species.


2018 ◽  
Author(s):  
Molly F Jenkins ◽  
Ethan P White ◽  
Allen H Hurlbert

Ecological communities are composed of a combination of core species that maintain local viable populations and transient species that occur infrequently due to dispersal from surrounding regions. Preliminary work indicates that while core and transient species are both commonly observed in community surveys of a wide range of taxonomic groups, their relative prevalence varies substantially from one community to another depending upon the spatial scale at which the community was characterized and its environmental context. We used a geographically extensive dataset of 968 bird community time series to quantitatively describe how the proportion of core species in a community varies with spatial scale and environmental heterogeneity. We found that the proportion of core species in an assemblage increased with spatial scale in a positive decelerating fashion with a concomitant decrease in the proportion of transient species. Variation in the shape of this scaling relationship between sites was related to regional environmental heterogeneity, with lower proportions of core species at a given scale associated with high environmental heterogeneity. This influence of scale and environmental heterogeneity on the proportion of core species may help resolve discrepancies between studies of biotic interactions, resource availability, and mass effects conducted at different scales, because the importance of these and other ecological processes are expected to differ substantially between core and transient species.


2019 ◽  
Vol 25 (1) ◽  
pp. 63-68
Author(s):  
Saulis Skuja ◽  
Gintautas Mozgeris ◽  
Rimgaudas Treinys

Sympatric species are likely to compete with one another unless there is a low degree of overlap in their resource use, in which case these species are able to coexist. Disclosing of biotic interactions between sympatric species is important from both theoretical and practical perspectives, especially when the species are of conservation concern.  However, environmental heterogeneity may introduce variation in the intensity of biotic interactions due to differential a varying species responses to the environmental gradient. In this study, we analysed the overlap in nesting sites between the internationally protected, mature, forest-dwelling Lesser Spotted Eagle Clanga pomarina and the Black Stork Ciconia nigra. The importance of landscape heterogeneity for habitat segregation between these species was also assessed. The nesting sites of 123 pairs of Lesser Spotted Eagles and 78 pairs of Black Storks, located across different landscapes of the Central, Central-Eastern and Eastern Lithuanian ecoregions were described. A series of discriminant analyses were performed to explore the pattern of habitat differentiation between species nesting in the above-mentioned regions. The habitat differentiation was estimated by niche overlap values (range 0-1, with a value 0.6 suggested to be the threshold between coexistence and competition). Comparison of nesting sites of mature forest-dwellers resulted in the niche overlap values for Central, Central-Eastern and Eastern regions being 0.5, 0.63 and 0.55, respectively. These results indicated relatively high niche overdispersion between nesting sites occupied by eagles and storks. Different variables and/or their combinations resulted in habitat differences in each ecoregion. Our data indicate that biotic interaction between species is mediated by environmental heterogeneity. Although our data tend to support the coexistence of the Black Stork and the Lesser Spotted Eagle, in certain regions these mature, forest-dwelling predators may use similar habitats and compete for prime sites under specific landscape structures. We, therefore, propose the necessity of the importance of a spatially-segregated estimation on biotic interactions when developing conservation programmes and allocating conservation actions within the target region.


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