Sex ratio dependent dispersal when sex ratios vary between patches

Nelson, Ronald M.; Greeff, Jaco M.

doi:10.1016/j.jtbi.2011.08.030

Cited by 9 publications

(10 citation statements)

References 56 publications

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“…In reality, con-specific density and mating opportunities (hence, sex-ratio in interaction with the mating system) are likely to interact in determining dispersal behaviours. Sex-biased dispersal and sex-ratio can ecologically and evolutionary influence each other (Bonte et al 2009, Meier et al 2011, Nelson and Greeff 2011, with considerable consequences for species' rate of spread (Miller et al 2011, Miller andInouye 2013).…”

Section: Discussionmentioning

confidence: 99%

Mechanistic modelling of animal dispersal offers new insights into range expansion dynamics across fragmented landscapes

et al. 2014

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Understanding and predicting the dynamics of range expansion is a major topic in ecology both for invasive species extending their ranges into non‐native regions and for species shifting their natural distributions as a consequence of climate change. In an increasingly modified landscape, a key question is ‘how do populations spread across patchy landscapes?‘ Dispersal is a central process in range expansion and while there is a considerable theory on how the shape of a dispersal kernel influences the rate of spread, we know much less about the relationships between emigration, movement and settlement rules, and invasion rates. Here, we use a simple, single species individual‐based model that explicitly simulates animal dispersal to establish how density‐dependent emigration and settlement rules interact with landscape characteristics to determine spread rates. We show that depending on the dispersal behaviour and on the risk of mortality in the matrix, increasing the number of patches does not necessarily maximise the spread rate. This is due to two effects: first, individuals dispersing at the expanding front are likely to exhibit lower net‐displacement as they typically do not travel far before finding a patch; secondly, with increasing availability of high quality habitat, density‐dependence in emigration and settlement can decrease the number of emigrants and their net‐displacement. The rate of spread is ultimately determined by the balance between net travelled distance, the dispersal mortality and the number of dispersing individuals, which in turn depend on the interaction between the landscape and the species’ dispersal behaviour. These results highlight that predicting spread rates in heterogeneous landscapes is a complex task and requires better understanding of the rules that individuals use in emigration, transfer and settlement decisions.

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Section: Discussionmentioning

confidence: 99%

Mechanistic modelling of animal dispersal offers new insights into range expansion dynamics across fragmented landscapes

et al. 2014

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“…Wild & Taylor () also produced a somewhat counterintuitive result: despite coevolution, knowledge of primary sex ratio is not required for predicting evolutionarily stable dispersal rates. Nelson & Greeff () point out that this result ceases to be true if one includes environmental and/or demographic stochasticity, as in this case the sex ratios no longer remain homogeneous across habitats. Without heterogeneity in sex ratios, a male cannot expect to improve his chance of finding a patch with a more favourable sex ratio by dispersing.…”

Section: Drivers Of Sex‐biased Dispersalmentioning

confidence: 99%

Sex‐biased dispersal: a review of the theory

2018

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Dispersal is ubiquitous throughout the tree of life: factors selecting for dispersal include kin competition, inbreeding avoidance and spatiotemporal variation in resources or habitat suitability. These factors differ in whether they promote male and female dispersal equally strongly, and often selection on dispersal of one sex depends on how much the other disperses. For example, for inbreeding avoidance it can be sufficient that one sex disperses away from the natal site. Attempts to understand sex‐specific dispersal evolution have created a rich body of theoretical literature, which we review here. We highlight an interesting gap between empirical and theoretical literature. The former associates different patterns of sex‐biased dispersal with mating systems, such as female‐biased dispersal in monogamous birds and male‐biased dispersal in polygynous mammals. The predominant explanation is traceable back to Greenwood's () ideas of how successful philopatric or dispersing individuals are at gaining mates or the resources required to attract them. Theory, however, has developed surprisingly independently of these ideas: models typically track how immigration and emigration change relatedness patterns and alter competition for limiting resources. The limiting resources are often considered sexually distinct, with breeding sites and fertilizable females limiting reproductive success for females and males, respectively. We show that the link between mating system and sex‐biased dispersal is far from resolved: there are studies showing that mating systems matter, but the oft‐stated association between polygyny and male‐biased dispersal is not a straightforward theoretical expectation. Here, an important understudied factor is the extent to which movement is interpretable as an extension of mate‐searching (e.g. are matings possible en route or do they only happen after settling in new habitat – or can females perhaps move with stored sperm). We also point out other new directions for bridging the gap between empirical and theoretical studies: there is a need to build Greenwood's influential yet verbal explanation into formal models, which also includes the possibility that an individual benefits from mobility as it leads to fitness gains in more than one final breeding location (a possibility not present in models with a very rigid deme structure). The order of life‐cycle events is likewise important, as this impacts whether a departing individual leaves behind important resources for its female or male kin, or perhaps both, in the case of partially overlapping resource use.

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“…(1) A male-biased sex ratio (Clobert et al. 2001; Ronce 2007; Nelson and Greeff 2011), though sex ratio is commonly female-biased in most aphid parasitoid species (Mackauer 1976; Sequeira and Mackauer 1993); (2) A local mate competition between males (Nelson and Greeff 2011; Greeff et al. 2003; Henry 2008), which has already been described for Aphidius parasitoids (Godfray 1994); (3) A reproductive strategy resulting in monogamous mating for A. ervi females and polygamous males (Godfray 1994; He and Wang 2008); (4) The existence of philopatry in female parasitoids (Johnstone et al.…”

Section: Discussionmentioning

confidence: 99%

“…Regarding the higher paternal half-sibs between than within parasitoid populations, several interacting factors could contribute to a greater dispersion of A. ervi males between populations. (1) A male-biased sex ratio (Clobert et al 2001;Ronce 2007;Nelson and Greeff 2011), though sex ratio is commonly female-biased in most aphid parasitoid species (Mackauer 1976;Sequeira and Mackauer 1993); (2) A local mate competition between males (Nelson and Greeff 2011; Greeff et al 2003;Henry 2008), which has already been described for Aphidius parasitoids (Godfray 1994); (3) A reproductive strategy resulting in monogamous mating for A. ervi females and polygamous males (Godfray 1994;He and Wang 2008); (4) The existence of philopatry in female parasitoids (Johnstone et al 2012) or host fidelity in females of A. ervi (Zepeda-Paulo et al 2013); and (5) the occurrence of protandry, in which male parasitoids emerge from their mummies before female parasitoids, a phenomenon described for several parasitoid species including A. ervi (Godfray 1994;He et al 2004). Therefore, males should be more likely to leave the natal host patch looking for suitable mates elsewhere when females and/or virgin females are absent, which is common when females exhibit a monogamous behavior (Martel et al 2008).…”

Section: Differential Dispersal Of Parasitoid Females and Malesmentioning

confidence: 99%

Does sex‐biased dispersal account for the lack of geographic and host‐associated differentiation in introduced populations of an aphid parasitoid?

Zepeda-Paulo

Lavandero

Maheo

et al. 2015

Ecology and Evolution

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Host recognition and use in female parasitoids strongly relies on host fidelity, a plastic behavior which can significantly restrict the host preferences of parasitoids, thus reducing the gene flow between parasitoid populations attacking different insect hosts. However, the effect of migrant males on the genetic differentiation of populations has been frequently ignored in parasitoids, despite its known impact on gene flow between populations. Hence, we studied the extent of gene flow mediated by female and male parasitoids by assessing sibship relationships among parasitoids within and between populations, and its impact on geographic and host-associated differentiation in the aphid parasitoid Aphidius ervi. We report evidences of a high gene flow among parasitoid populations on different aphid hosts and geographic locations. The high gene flow among parasitoid populations was found to be largely male mediated, suggested by significant differences in the distribution of full-sib and paternal half-sib dyads of parasitoid populations.

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Sex ratio dependent dispersal when sex ratios vary between patches

Cited by 9 publications

References 56 publications

Mechanistic modelling of animal dispersal offers new insights into range expansion dynamics across fragmented landscapes

Mechanistic modelling of animal dispersal offers new insights into range expansion dynamics across fragmented landscapes

Sex‐biased dispersal: a review of the theory

Does sex‐biased dispersal account for the lack of geographic and host‐associated differentiation in introduced populations of an aphid parasitoid?

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