Conflict, compensation, and plasticity: Sex‐specific, individual‐level trade‐offs in green anole (Anolis carolinensis) performance

Abstract

Trade‐offs in performance expression occur because animals must perform multiple whole‐organism performance tasks that place conflicting demands on shared underlying morphology. Although not always detectable within populations, such trade‐offs may be apparent when analyzed at the level of the individual, particularly when all of the available data are taken into account as opposed to only maximum values. Detection of performance trade‐offs is further complicated in species where sexual dimorphism drives performance differences between males and females, leading potentially to differing patterns of trade‐offs within each sex. We tested for within‐ and between‐individual trade‐offs among three whole‐organism performance traits (sprint speed, endurance, and bite force) in adult male and female Anolis carolinensis lizards using all of the measured performance data. Sprinting and endurance did not trade‐off among individuals in either sex, but we found a significant negative among‐individual relationship between sprint speed and bite force in females only, likely driven by the mechanical burden of larger than optimal heads imposed on females through intralocus sexual conflict. We also found evidence for marked within‐individual plasticity in male bite force, but no within‐individual trade‐offs between any traits in either sex. These data offer new insight into the sex‐specific nature of performance trade‐offs and plasticity and, ultimately, into the constraints on multivariate performance evolution.

Sprint speed is unaffected by dietary manipulation in trained male Anolis carolinensis lizards

“…Indeed, diet‐restricted but protein‐supplemented, sprint‐trained animals exhibited both the greatest loss of mass and the largest decrease in bite force over the course of the experiment, but with no accompanying significant loss of sprint speed (Figure a,b). Our results for bite force plasticity match those of both Lailvaux et al () and Lailvaux et al () who found clear evidence of plasticity in male bite force in A. carolinensis . The lack of similar plasticity in sprint speed is therefore novel and represents scope for understanding the mechanisms whereby certain traits may be shielded against diminished expression associated with reduced resource availability.…”

“…The results of our (admittedly crude) protein treatment notwithstanding, it is notable that sprint speed did not differ between lizards on a restricted diet and those on an ad libitum diet, emphasizing the seeming insensitivity of sprint speed to dietary restriction in A. carolinensis. This result is consistent with the ecology of green anoles, which exhibit low movement rates in nature characteristic of organisms that rely more on sprinting than on endurance (Irschick, 2000;Jenssen, Greenberg, & Hovde, 1995) and whose movement rates also are unaffected by sprint training (Husak & Lailvaux, 2019), and also with recent data showing that sprint speed shows significant repeatability in green anoles (Lailvaux, Cespedes, & Houslay, 2019). It is also unlikely that lizards in the diet-restricted groups were able to compensate for compromised sprint speed because of their lower body masses, as sprinting in lizards is not limited by power output (Farley, 1997; see also Irschick, Vanhooydonck, Herrel, & Andronescu, 2003).…”

Reproductive phenotype predicts adult bite‐force performance in sex‐reversed dragons (Pogona vitticeps)

“…Bite force is an important measure of whole‐organism performance that may differ between males and females (Gvozdík & Van Damme, 2003; Lailvaux, Cespedes, & Houslay, 2019; Lappin, Hamilton, & Sullivan, 2006; Lappin & Husak, 2005; Lappin & Jones, 2014; McLean et al, 2016). Some male iguanian lizards use their jaws as a weapon to fight other males or to intimidate and restrain female lizards (Lailvaux et al, 2019; Lappin & Husak, 2005; Lappin, Brandt, Husak, Macedonia, & Kemp, 2006; Lappin, Hamilton et al, 2006; McLean et al, 2016; McLean & Stuart‐Fox, 2015). In eastern collared lizards ( Crotaphytus collaris ), the bite force of adult males is a strong predictor of access to females, mating success, and genetic paternity, whereas body size is not; the greater bite force of males is associated with considerably greater head dimensions (likely related to having larger jaw muscles) than females (Husak, Lappin, & Van Den Bussche, 2009; Lappin & Husak, 2005).…”

Underwater compensation for exaggerated weaponry: The role of morphology and environment on crab locomotor performance

“…Despite females having small claws when compared to males, claws might be larger than the optimal due to selection on the male trait (Husak & Swallow, ). If this is true, then we can expect compensation in the sex without the exaggerated trait as well (e.g., Cameron, Wynn, & Wilson, ; Lailvaux, Cespedes, & Houslay, ). Our data does not quite fit that expectation because females are faster than males.…”