Physiological Variation and Allometry in Western Whiptail Lizards (Cnemidophorus tigris) from a Transect across a Persistent Hybrid Zone

Dohm, Michael R.; Garland, Theodore; Cole, Charles J.; Townsend, Carol R.

doi:10.2307/1447696

Cited by 19 publications

(21 citation statements)

References 37 publications

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“…Stronger evidence would be provided by demonstrating that males show higher endurance than females after adjusting statistically for correlations with body size. Existing empirical studies are mixed regarding this possibility in lizards (Garland & Else 1987; Cullum 1998; Dohm et al . 1998).…”

Section: Discussionmentioning

confidence: 99%

Evaluating performance costs of sexually selected traits

2007

Functional Ecology

118

157

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Summary1. Aspects of locomotor performance are thought to be important in a variety of natural contexts, including foraging and escaping from predators. The role of locomotor abilities in sexual selection is less well documented, but is probably of wide importance. 2. Sexual selection may exaggerate traits beyond their optimum with respect to biomechanical or physiological function, thus imposing 'costs' of various types. Locomotor performance, in conjunction with its lower-level determinants and its behavioural and ecological consequences, constitutes an ideal set of phenotypes with which to study such costs. 3. Organisms may possess traits that compensate for the negative effects of sexually selected traits on performance abilities. Ignoring these may lead to erroneous conclusions about the cost of a putatively sexually selected trait. At the same time, ignoring the effects of sexual selection on functionally important traits may lead us to underestimate their functional significance. 4. Many properties of organisms are affected by, or at least correlate with, overall body size, so this must be considered in any study of adaptation or sexual selection. For interspecific or interpopulation comparative studies, phylogeny must also be considered in statistical analyses. 5. We present a hypothetical data set that illustrates the perils of ignoring potential compensatory mechanisms when studying the costs of a sexually selected trait. We also discuss different ways of studying costs, including analyses of a single sex and of the differences between the sexes.

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Section: Discussionmentioning

confidence: 99%

Evaluating performance costs of sexually selected traits

2007

Functional Ecology

118

157

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“…Bonine and Garland, 1999). Aspidoscelis is the archetypal active, widely foraging lizard and has exceptionally high stamina in addition to being a fast sprinter (Garland, 1994;Dohm et al, 1998;Bonine and Garland, 1999;Bonine, 2001).…”

Section: Discussionmentioning

confidence: 99%

Muscle fiber-type variation in lizards (Squamata) and phylogenetic reconstruction of hypothesized ancestral states

Bonine

Gleeson

Garland

2005

Journal of Experimental Biology

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Previously, we found that phrynosomatid lizards, a diverse group common in the southwestern USA, vary markedly in fiber-type composition of the iliofibularis (a hindlimb muscle important in locomotion). Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. The variation in muscle fiber-type composition for 11 phrynosomatid species is attributable mainly to differences between the sand-and horned-lizard subclades. Here, we expand the phrynosomatid database with three additional species and compare these results with data collected for 10 outgroup (distantly related) species. Our goal was to determine if the patterns found in Phrynosomatidae hold across a broader phylogenetic range of the extant lizards and to elucidate the evolution of muscle fiber-type composition and related traits. To allow for meaningful comparisons, data were collected from species that are primarily terrestrial and relatively small in size (3.5-65·g body mass). Results indicate that the fiber-type variation observed within the Phrynosomatidae almost spans the range of variation observed in our sample of 24 species from eight families.However, one species of Acanthodactylus (Lacertidae) had a consistent region of large tonic fibers (that did not stain darkly for either succinic dehydrogenase or myosin ATPase activity), a fiber-type only occasionally seen in the other 23 species examined. Many species have a large proportion of either fast-twitch glycolytic (FG; e.g. sand lizards and Aspidoscelis) or fast-twitch oxidative-glycolytic (FOG) fibers (e.g. horned lizards), with the slow-oxidative proportion occupying only 1-17% of the iliofibularis. Importantly, the negative relationship between FG and FOG composition observed in Phrynosomatidae appears to be a characteristic of lizards in general, and could lead to functional trade-offs in aspects of locomotor performance, as has previously been reported for Lacertidae. Reconstruction of ancestral trait values by use of phylogenetically based statistical methods indicates especially large changes in fiber-type composition during the evolution of horned lizards.

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“…Interestingly, there are also instances where there are no differences in metabolic rates that can be attributed to the endocrine system (e.g. Western Whiptail Lizards, Cnemidophorus tigris ; Dohm et al . 1998).…”

Section: Discussionmentioning

confidence: 99%

Sex‐specific differences in cardiovascular performance of a centrarchid fish are only evident during the reproductive period

Cooke

2004

Functional Ecology

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Summary 1.Although in birds and mammals sex-specific differences in organismal performance and physiology are well documented, comparatively little is known about the influence of sex or reproductive status on fish performance or metabolism. 2. In this study, the resting cardiovascular performance of male and female Largemouth Bass Micropterus salmoides was contrasted across three seasons and different reproductive states including the spring when nesting males provide sole parental care. Doppler flow probes were used to monitor resting cardiac output ( Q ) and its two components (heart rate, f H and stroke volume, SV H ). 3. During the spring when Largemouth Bass were engaged in reproduction (at 21 ° C), parental male nesting fish had heightened resting cardiovascular rates (both Q and f H ) relative to non-nesting males and females. In the summer at higher water temperatures (24 ° C), and in the autumn at water temperatures similar to the reproductive period (21 ° C), resting cardiovascular variables were similar between sexes. 4. This study found that there are sex-based differences in fish physiological performance. However, the sex-specific differences were evident only during the reproductive period, and in particular for male fish actively engaged in the nesting phase of parental care, indicating a likely role of the endocrine system.

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Physiological Variation and Allometry in Western Whiptail Lizards (Cnemidophorus tigris) from a Transect across a Persistent Hybrid Zone

Cited by 19 publications

References 37 publications

Evaluating performance costs of sexually selected traits

Evaluating performance costs of sexually selected traits

Muscle fiber-type variation in lizards (Squamata) and phylogenetic reconstruction of hypothesized ancestral states

Sex‐specific differences in cardiovascular performance of a centrarchid fish are only evident during the reproductive period

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