Frequency of Occurrence and Population-Dynamic Consequences of Different Forms of Density-Dependent Emigration

Harman, Rachel R.; Goddard, Jerome; Shivaji, R.; Cronin, James T.

doi:10.1086/708156

Cited by 36 publications

(83 citation statements)

References 189 publications

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“…This was also supported by a recent literature review on densitydependent emigration, which identified positive DDD as the most common one, followed by negative DDD and nonlinear DDD patterns (Harman et al 2020).…”

supporting

confidence: 72%

“…These densities were chosen based on an earlier DDD study on the ancestral populations of these flies (Mishra et al 2018b). As density can affect the physiology and dispersal of individuals in multiple possible ways and across life stages (Matthysen 2005;Harman et al 2020), we decided to limit our study to adult density and adult dispersal. With a uniform rearing until the adult stage (Text S1), this ensured that adult density was the only environmental factor that differed among these four treatments.…”

Section: Experimental Designmentioning

confidence: 99%

“…The specifics of a given dispersal event, in turn, are regulated by numerous biotic and abiotic factors (Bowler and Benton 2005;Matthysen 2012). One such factor that can be a prominent cause of variation in the dispersal patterns of many species is the local population density, leading to density-dependent dispersal (DDD) (reviewed in Matthysen 2005;Harman et al 2020).…”

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confidence: 99%

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Dispersal evolution diminishes the negative density dependence in dispersal

2020

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In many organisms, dispersal varies with the local population density. Such patterns of density‐dependent dispersal (DDD) are expected to shape the dynamics, spatial spread, and invasiveness of populations. Despite their ecological importance, empirical evidence for the evolution of DDD patterns remains extremely scarce. This is especially relevant because rapid evolution of dispersal traits has now been empirically confirmed in several taxa. Changes in DDD of dispersing populations could help clarify not only the role of DDD in dispersal evolution, but also the possible pattern of subsequent range expansion. Here, we investigate the relationship between dispersal evolution and DDD using a long‐term experimental evolution study on Drosophila melanogaster. We compared the DDD patterns of four dispersal‐selected populations and their non‐selected controls. The control populations showed negative DDD, which was stronger in females than in males. In contrast, the dispersal‐selected populations showed DDD, where neither males nor females exhibited DDD. We compare our results with previous evolutionary predictions that focused largely on positive DDD, and highlight how the direction of evolutionary change depends on the initial DDD pattern of a population. Finally, we discuss the implications of DDD evolution for spatial ecology and evolution.

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confidence: 72%

Section: Experimental Designmentioning

confidence: 99%

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confidence: 99%

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Dispersal evolution diminishes the negative density dependence in dispersal

2020

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Section: Introductionmentioning

confidence: 99%

Dispersal evolution diminishes the negative density dependence in dispersal

Mishra

Chakraborty

Dey

2020

Preprint

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18In many organisms, dispersal varies with the local population density. Such patterns of density-19 dependent dispersal (DDD) are expected to shape the dynamics, spatial spread and invasiveness 20 of populations. Despite their ecological importance, empirical evidence for the evolution of DDD 21 patterns remains extremely scarce. This is especially relevant because rapid evolution of 22 dispersal traits has now been empirically confirmed in several taxa. Changes in DDD of 23 dispersing populations could help clarify not only the role of DDD in dispersal evolution, but 24 also the possible pattern of subsequent range expansion. Here, we investigate the relationship 25 between dispersal evolution and DDD using a long-term experimental evolution study on 26 Drosophila melanogaster. We compared the DDD patterns of four dispersal-selected populations 27 and their non-selected controls. The control populations showed negative DDD, which was 28 stronger in females than in males. In contrast, the dispersal-selected populations showed density-29 independent dispersal, where neither males nor females exhibited DDD. Our results are contrary 30 to the expectations from previous studies, which predict that dispersal evolution at range edges 31 leads to stronger negative DDD patterns. We discuss the possible reasons for this divergence 32 from earlier predictions and its implications for spatial ecology and evolution. 33 34 Keywords: density-dependent dispersal, sex-biased dispersal, Drosophila melanogaster, 35 dispersal propensity, temporal dispersal profile, spatial sorting 36 37 Biological dispersal, an integral part of the life history in many taxa (Bonte and Dahirel 2017), is 39 a major determinant of spatial distribution of living organisms. Dispersal patterns influence 40 several ecological phenomena, including biological invasions, range expansions and community 41 assembly (Bowler and Benton 2005; Clobert et al. 2009; Lowe and McPeek 2014). The specifics 42 of a given dispersal event, in turn, are regulated by numerous biotic and abiotic factors (Bowler 43 and Benton 2005; Matthysen 2012). One such factor that can be a prominent cause of variation 44 in the dispersal patterns of many species is the local population density, leading to density-45 dependent dispersal (DDD) (reviewed in Matthysen 2005; Harman et al. 2020). 46Population density can affect the movement of individuals in many ways. For instance, DDD is 47 defined as positive when the per capita dispersal increases with increasing population density, 48 often manifesting as greater proportional movement from dense regions to sparse regions (e.g. 49 Aars and Ims 2000; De Meester and Bonte 2010; Bitume et al. 2013; Lutz et al. 2015). Similarly, 50 negative DDD implies a reduction in per capita movement with increasing population density, 51 resulting in greater aggregation in crowded regions and higher net emigration from sparse 52 regions (e.g. Andreassen and Ims 2001; Baguette et al. 2011; Pennekamp et al. 2014; Mishra et 53 al. 2018b). In addition, r...

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“…As the cost-benefit balance of dispersal is expected to vary depending on individual phenotype and experienced conditions, dispersal is often highly context- and phenotype-dependent (Bowler & Benton, 2005; Clobert et al , 2012; Baines, Ferzoco & McCauley, 2019; Endriss et al , 2019). This multicausality of dispersal likely explains why even well-studied environmental factors, like increased population density and competition, may lead to very different dispersal responses depending on populations and species (Bowler & Benton, 2005; Matthysen, 2005; Kim, Torres & Drummond, 2009; Fronhofer, Kropf & Altermatt, 2015; Baines et al , 2019; Harman et al , 2020). To understand the context-dependency of dispersal, it is thus necessary to study a broader range of life histories and contexts, including organisms that have alternative strategies to escape negative environmental conditions, such as dormancy, sometimes seen as a form of “dispersal in time” (Buoro & Carlson, 2014).…”

Section: Introductionmentioning

confidence: 99%

Increased population density depresses activity but does not influence emigration in the snailPomatias elegans

Dahirel

Menut

Ansart

2020

Preprint

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Dispersal is a key trait linking ecological and evolutionary dynamics, allowing organisms to optimize fitness expectations in spatially and temporally heterogeneous environments. Some organisms can both actively disperse or enter a reduced activity state in response to challenging conditions, and both responses may be under a trade-off. To understand how such organisms respond to changes in environmental conditions, we studied the dispersal and activity behaviour in the gonochoric land snail Pomatias elegans, a litter decomposer that can reach very high local densities, across a wide range of ecologically relevant densities. We found that crowding up to twice the maximal recorded density had no detectable effect on dispersal tendency in this species, contrary to previous results in many hermaphroditic snails. Pomatias elegans is nonetheless able to detect population density; we show they reduce activity rather than increase dispersal in response to crowding. We discuss these results based on the ability of many land snails to enter dormancy for extended periods of time in case of unfavourable conditions. We propose that dormancy (“dispersal in time”) may be more advantageous in species with especially poor movement abilities, even by land mollusc standards, like P. elegans. Interestingly, dispersal and activity were correlated independently of density; this dispersal syndrome may reflect a dispersal-dormancy trade-off at the individual level. Additionally, we found snails with heavier shells relative to their size tended to be less mobile, which may reflect physical and metabolic constraints on movement and/or survival during inactivity. We finally discuss how the absence of density-dependent dispersal may explain why P. elegans is often found at very high local densities, and the possible consequences for ecosystem functioning and litter decomposition.

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Frequency of Occurrence and Population-Dynamic Consequences of Different Forms of Density-Dependent Emigration

Cited by 36 publications

References 189 publications

Dispersal evolution diminishes the negative density dependence in dispersal

Dispersal evolution diminishes the negative density dependence in dispersal

Dispersal evolution diminishes the negative density dependence in dispersal

Increased population density depresses activity but does not influence emigration in the snailPomatias elegans

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