The Young, the Weak and the Sick: Evidence of Natural Selection by Predation

Genovart, Meritxell; Negre, Nieves; Tavecchia, Giacomo; Bistuer, Ana; Parpal, Luís; Oro, Daniel

doi:10.1371/journal.pone.0009774

Cited by 103 publications

(82 citation statements)

References 36 publications

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“…Empirical studies of changes in fat storage under changes in predation pressure largely support the idea that fat storage is reduced when predation pressure (or perceived predation pressure) increases (Gosler et al, 1995;Cresswell, 1998;Rogers, 2015;Pascual and Carlos Senar, 2015;Zimmer et al, 2011;MacLeod et al, 2007;Cimprich and Moore, 2006;Macleod et al, 2005a,b;Ydenberg et al, 2004;Pérez-Tris et al, 2004;Piersma et al, 2003;Gentle and Gosler, 2001;van der Veen, 1999;Carrascal and Polo, 1999;Fransson and Weber, 1997;Pravosudov and Grubb, 1998;Rogers, 1987;Witter et al, 1994; but see Lilliendahl 1997Lilliendahl , 1998. However, studies of birds killed by predators do not indicate that fatter birds are killed more frequently (Sullivan, 1989;Whitfield et al, 1999;Møller and Erritzøe, 2000;Genovart et al, 2010); indeed, some studies suggest that leaner birds are more prone to predation risk (Dierschke, 2003;Yosef et al, 2011).…”

Section: Set-point Theorymentioning

confidence: 99%

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The evolution of body fatness: trading off disease and predation risk

Speakman

2018

Journal of Experimental Biology

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Human obesity has a large genetic component, yet has many serious negative consequences. How this state of affairs has evolved has generated wide debate. The thrifty gene hypothesis was the first attempt to explain obesity as a consequence of adaptive responses to an ancient environment that in modern society become disadvantageous. The idea is that genes (or more precisely, alleles) predisposing to obesity may have been selected for by repeated exposure to famines. However, this idea has many flaws: for instance, selection of the supposed magnitude over the duration of human evolution would fix any thrifty alleles (famines kill the old and young, not the obese) and there is no evidence that hunter-gatherer populations become obese between famines. An alternative idea (called thrifty late) is that selection in famines has only happened since the agricultural revolution. However, this is inconsistent with the absence of strong signatures of selection at single nucleotide polymorphisms linked to obesity. In parallel to discussions about the origin of obesity, there has been much debate regarding the regulation of body weight. There are three basic models: the setpoint, settling point and dual-intervention point models. Selection might act against low and high levels of adiposity because food unpredictability and the risk of starvation selects against low adiposity whereas the risk of predation selects against high adiposity. Although evidence for the latter is quite strong, evidence for the former is relatively weak. The release from predation ∼2-million years ago is suggested to have led to the upper intervention point drifting in evolutionary time, leading to the modern distribution of obesity: the drifty gene hypothesis. Recent critiques of the dual-intervention point/ drifty gene idea are flawed and inconsistent with known aspects of energy balance physiology. Here, I present a new formulation of the dual-intervention point model. This model includes the novel suggestion that food unpredictability and starvation are insignificant factors driving fat storage, and that the main force driving up fat storage is the risk of disease and the need to survive periods of pathogen-induced anorexia. This model shows why two independent intervention points are more likely to evolve than a single set point. The molecular basis of the lower intervention point is likely based around the leptin pathway signalling. Determining the molecular basis of the upper intervention point is a crucial key target for future obesity research. A potential definitive test to separate the different models is also described.

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Section: Set-point Theorymentioning

confidence: 99%

“…Foraging might then exacerbate the problem of energy imbalance. Second, the animal may be more susceptible to predation (Genovart et al, 2010). We have all probably experienced having an illness, and are aware that when you are ill you do not want to run around and eat food.…”

Section: Dual-intervention Point Model and 'Drifty Gene' Hypothesismentioning

confidence: 99%

The evolution of body fatness: trading off disease and predation risk

Speakman

2018

Journal of Experimental Biology

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“…The arms race between predators and prey Natural selection by selective removal of prey can have a profound influence on prey behavior, morphology, and physiology (Genovart et al 2010, Benkman et al 2013, Vedder et al 2014. Under the selection pressures imposed by predators, prey continuously evolve behavioral, morphological, and physiological defense mechanisms (Dawkins and Krebs 1979).…”

Section: Depletion Of Cockle Densities and Community Effectsmentioning

confidence: 99%

Natural selection by pulsed predation: survival of the thickest

Bijleveld

Twietmeyer

Piechocki

et al. 2015

Ecology

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Abstract. Selective predation can lead to natural selection in prey populations and may alleviate competition among surviving individuals. The processes of selection and competition can have substantial effects on prey population dynamics, but are rarely studied simultaneously. Moreover, field studies of predator-induced short-term selection pressures on prey populations are scarce. Here we report measurements of density dependence in body composition in a bivalve prey (edible cockle, Cerastoderma edule) during bouts of intense predation by an avian predator (Red Knot, Calidris canutus). We measured densities, patchiness, morphology, and body composition (shell and flesh mass) of cockles in a quasiexperimental setting, i.e., before and after predation in three similar plots of 1 ha each, two of which experienced predation, and one of which remained unvisited in the course of the short study period and served as a reference. An individual's shell and flesh mass declined with cockle density (negative density dependence). Before predation, cockles were patchily distributed. After predation, during which densities were reduced by 78% (from 232 to 50 cockles/m 2 ), the patchiness was substantially reduced, i.e., the spatial distribution was homogenized. Red Knots selected juvenile cockles with an average length of 6.9 6 1.0 mm (mean 6 SD). Cockles surviving predation had heavier shells than before predation (an increase of 21.5 percentage points), but similar flesh masses. By contrast, in the reference plot shell mass did not differ statistically between initial and final sampling occasions, while flesh mass was larger (an increase of 13.2 percentage points). In this field study, we show that Red Knots imposed a strong selection pressure on cockles to grow fast with thick shells and little flesh mass, with selection gradients among the highest reported in the literature.

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“…Fitness distributions supporting the idea of truncation were observed in social insects in the wild [81]. Overall, truncation selection methods approximate natural selection by predation [82], when the weakest are eliminated from the gene pool. They also resemble to some extent a purifying selection, which removes deleterious mutations [83].…”

Section: Discussionmentioning

confidence: 57%

Selection methods regulate evolution of cooperation in digital evolution

Lichocki

Floreano

Keller

2014

J. R. Soc. Interface.

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A key, yet often neglected, component of digital evolution and evolutionary models is the 'selection method' which assigns fitness (number of offspring) to individuals based on their performance scores (efficiency in performing tasks). Here, we study with formal analysis and numerical experiments the evolution of cooperation under the five most common selection methods ( proportionate, rank, truncation-proportionate, truncation-uniform and tournament). We consider related individuals engaging in a Prisoner's Dilemma game where individuals can either cooperate or defect. A cooperator pays a cost, whereas its partner receives a benefit, which affect their performance scores. These performance scores are translated into fitness by one of the five selection methods. We show that cooperation is positively associated with the relatedness between individuals under all selection methods. By contrast, the change in the performance benefit of cooperation affects the populations' average level of cooperation only under the proportionate methods. We also demonstrate that the truncation and tournament methods may introduce negative frequency-dependence and lead to the evolution of polymorphic populations. Using the example of the evolution of cooperation, we show that the choice of selection method, though it is often marginalized, can considerably affect the evolutionary dynamics.

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The Young, the Weak and the Sick: Evidence of Natural Selection by Predation

Cited by 103 publications

References 36 publications

The evolution of body fatness: trading off disease and predation risk

The evolution of body fatness: trading off disease and predation risk

Natural selection by pulsed predation: survival of the thickest

Selection methods regulate evolution of cooperation in digital evolution

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