A GENETIC PERSPECTIVE ON RAPID EVOLUTION IN CANE TOADS (<i>RHINELLA MARINA</i>)

Rollins, Lee A.; Richardson, Mark F.; Shine, Richard

doi:10.1002/9781119072799.ch18

Cited by 22 publications

(25 citation statements)

References 88 publications

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“…; Myles‐Gonzalez et al . ) and a recent study found that genes underlying metabolic processes are upregulated in dispersive cane toads (Rollins, Richardson & Shine ). Further investigations into the association between MR and movement are warranted, particularly given the potential involvement of genetic and epigenetic mechanisms (Rollins, Richardson & Shine ).…”

Section: Discussionmentioning

confidence: 94%

Functional traits in red flour beetles: the dispersal phenotype is associated with leg length but not body size nor metabolic rate

2016

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Summary Individuals vary in their ability to disperse. Much of this variation can be described by covarying phenotypic traits that are related to dispersal (constituting the ‘dispersal phenotype’ or ‘dispersal syndrome’), but the nature of the associations among these traits is not well understood. Unravelling the associations among traits that potentially constitute the dispersal phenotype provides a foundation for understanding evolutionary trade‐offs due to variation in dispersal. Here, we tested five predictions pertaining to the relationships among physiological, morphological and movement traits that are associated with dispersal, using a species with a long history as a laboratory model for studying ecological phenomena, red flour beetles (Tribolium castaneum). We identified a dominant axis of movement ability that describes variation in dispersal‐related movement traits. Individuals that scored positively on this axis moved at higher speed, travelled longer distances, had lower movement intermittency and dispersed quicker to a specified area. Relative leg length, but not body size nor routine metabolic rate related positively with movement ability, indicating a likely mechanistic relationship between increased stride length and movement ability. Our data suggest that the dispersal phenotype may be more strongly linked to morphological traits than physiological ones. We demonstrate that associations among many functional traits do not necessarily conform to a priori expectations, and predict that the substantial intraspecific variation in trait values may be important for selection. Movement is a complex behavioural trait, but it has a mechanistic basis in locomotor morphology that warrants further exploration. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12772/suppinfo is available for this article.

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Section: Discussionmentioning

confidence: 94%

Functional traits in red flour beetles: the dispersal phenotype is associated with leg length but not body size nor metabolic rate

2016

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“…), greater locomotor endurance (Llewelyn et al . ) and upregulation of genes involved in metabolism and cell repair (Rollins, Richardson & Shine ). These toads have also displayed patterns that are contrary to predictions of expected dispersal for specific phenotypes.…”

Section: Introductionmentioning

confidence: 99%

Locomotor endurance predicts differences in realized dispersal between sympatric sexual and unisexual salamanders

Denton¹,

Greenwald

Gibbs³

2016

Functional Ecology

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Summary Dispersal is the central mechanism that determines connectivity between populations yet few studies connect the mechanisms of movement with realized dispersal in natural populations. To make such a link, we assessed how physiological variation among individuals predicted dispersal in natural populations of unisexual (all‐female) and sexual Ambystoma salamanders on the same fragmented landscape in Ohio. Specifically, we assessed variation in a trait that influences long‐distance animal movement (locomotor endurance) and determined whether variation in endurance matched patterns of realized dispersal assessed using genetic assignment tests. A possible mechanism for why unisexuals would have lower locomotor endurance than a sympatric sexual species (Ambystoma texanum) is the potential energetic cost of evolutionarily mismatched mitochondrial and nuclear genomes within polyploid unisexuals. We found that sexuals walked four times farther than unisexuals during treadmill endurance trials that mimic the locomotor endurance required for dispersal. We then applied landscape genetic methods to identify dispersed adults and quantify realized dispersal. We show that the differences in locomotor endurance between unisexual and sexual salamanders scale to realized dispersal: dispersing sexual individuals travelled approximately twice the distance between presumed natal wetlands and the site of capture compared to dispersing unisexuals. This study links variation in individual performance in terms of endurance with realized dispersal in the field and suggests a potential mechanism (physiological limitation due to mitonuclear mismatch) for the reduced endurance of unisexual individuals relative to sexual individuals although we discuss other possible explanations. The differences in dispersal between these two types of salamanders also informs our understanding of sexual/unisexual coexistence by suggesting that unisexuals are at a competitive disadvantage in terms of colonization ability under a extinction‐colonization model of coexistence. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12813/suppinfo is available for this article.

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“…Also, low densities of conspecifics at the range edge may favour “r‐selected” life‐history attributes in a situation of rapid population growth and minimal intraspecific competition (Burton, Phillips, & Travis, ). The rapid maturation and high fecundity of many invasive species mean that such novel challenges may result in rapid evolutionary changes—thereby providing ideal model systems with which to explore the process of evolution (Chuang & Peterson, ; Moran & Alexander, ; Rollins, Richardson, & Shine, ).…”

Section: Introductionmentioning

confidence: 99%

May the (selective) force be with you: Spatial sorting and natural selection exert opposing forces on limb length in an invasive amphibian

Clarke

Shine

Phillips

2019

J of Evolutionary Biology

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Spatial sorting on invasion fronts drives the evolution of dispersive phenotypes, and in doing so can push phenotypes in the opposite direction to natural selection. The invasion of cane toads (Rhinella marina) through tropical Australia has accelerated over recent decades because of the accumulation of dispersal‐enhancing traits at the invasion front, driven by spatial sorting. One such trait is the length of the forelimbs: invasion‐front toads have longer arms (relative to body length) in comparison with populations 10–20 years after invasion. Such a shift likely has fitness consequences: an increase of forearm length would decrease the strength with which a male could cling to a female during amplexus and so render such a male less competitive in competition for mates, compared to short‐armed conspecifics. Our laboratory trials of attachment strength confirmed that males with relatively longer arms were easier to displace, and competition trials show higher duration of amplexus for males with shorter arms. Together with the sharp cline in limb length observed behind the invasion front, these results imply an opposition of selective forces: spatial sorting optimizes dispersal, but as this force wanes behind the invasion front, we see the primacy of natural selection reassert itself.

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A GENETIC PERSPECTIVE ON RAPID EVOLUTION IN CANE TOADS (RHINELLA MARINA)

Cited by 22 publications

References 88 publications

Functional traits in red flour beetles: the dispersal phenotype is associated with leg length but not body size nor metabolic rate

Functional traits in red flour beetles: the dispersal phenotype is associated with leg length but not body size nor metabolic rate

Locomotor endurance predicts differences in realized dispersal between sympatric sexual and unisexual salamanders

May the (selective) force be with you: Spatial sorting and natural selection exert opposing forces on limb length in an invasive amphibian

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