Ecology of Sexual Dimorphism and Clinal Variation of Coloration in a Damselfly

Cooper, Idelle A.

doi:10.1086/656491

Cited by 55 publications

(68 citation statements)

References 35 publications

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“…In species where morphs differ in the darkness or melanization of their colouration, temperature or light effects are often determined to be a proximate cause for geographic variation in morph frequencies (de Jong and Brakefield, 1998;Galeotti et al, 2003;Phifer-Rixey et al, 2008). However, in colour morphs that do not differ in any systematic way along a "dark-light" axis, other factors may be more important in determining spatial clines, such as visibility in the water column (Terai et al, 2006) or UV resistance (Cooper, 2010). Large-scale geographic pattems of morph frequency variation may often be coupled with stochastic variation on a small scale (Cook, 1998;Barrett et al, 2004;Oxford, 2005).…”

Section: Introductionmentioning

confidence: 99%

Morph-specific and sex-specific temperature effects on morphology in the colour polymorphic damselfly Ischnura elegans

Abbott

2013

Animal Biol

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Colour polymorphic species with extensive ranges often exhibit large-scale geographic patterns of morph frequency variation. Because colour polymorphism is associated with correlated differences in multiple traits, such as thermal performance, a likely proximate explanation for such patterns is morph-specific responses to temperature variation. The colour polymorphic Blue-tailed damselfiy Ischnura elegans exhibits large-scale geographic variation in morph frequencies, but the possibility that temperature is a proximate explanation for the latitudinal cline in morph frequencies has only ever been tested within a single developmental stage (egg survival and hatching time), where no difference between the morphs was found. I therefore carried out a temperature manipulation on larvae of /. elegans which I raised to maturity in the laboratory. I found that individuals exhibited incomplete compensatory growth after being exposed to cold temperatures, and that individuals which did not emerge successfully and those that experienced cold temperatures had more juvenile morphology in the last instar. In addition, there were sex-specific and morph-specific effects of temperature on adult morphology, such that sexual size dimorphism was increased when individuals experienced warm temperatures throughout the larval stage, and that cold temperatures tended to result in larger size of androchromes and their offspring compared to the other morphs. These results are generally consistent with the large-scale geographic variation in morph frequencies found in this species.

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Section: Introductionmentioning

confidence: 99%

Morph-specific and sex-specific temperature effects on morphology in the colour polymorphic damselfly Ischnura elegans

Abbott

2013

Animal Biol

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“…For example, in the polymorphic snail Littorina obtusata , shell colour morph frequencies changed gradually in accordance with environmental temperature regimes within and between estuaries [13], suggesting that temperature acts as a major selective agent to maintain this colour polymorphism. Other examples in which morph frequencies relate to ecological variables involve niche occupancy in the barn owl, Tito alba [19], altitude related solar radiation in the polymorphic damselfly Megalagrion calliphya [20] and soil coloration to improve crypsis in Agouti mice [21]. In many cases, spatial morph frequency variation resembles a cline.…”

Section: Introductionmentioning

confidence: 99%

Biogeographical Survey Identifies Consistent Alternative Physiological Optima and a Minor Role for Environmental Drivers in Maintaining a Polymorphism

2012

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The contribution of adaptive mechanisms in maintaining genetic polymorphisms is still debated in many systems. To understand the contribution of selective factors in maintaining polymorphism, we investigated large-scale (>1000 km) geographic variation in morph frequencies and fitness-related physiological traits in the damselfly Nehalennia irene. As fitness-related physiological traits, we investigated investment in immune function (phenoloxidase activity), energy storage and fecundity (abdomen protein and lipid content), and flight muscles (thorax protein content). In the first part of the study, our aim was to identify selective agents maintaining the large-scale spatial variation in morph frequencies. Morph frequencies varied considerably among populations, but, in contrast to expectation, in a geographically unstructured way. Furthermore, frequencies co-varied only weakly with the numerous investigated ecological parameters. This suggests that spatial frequency patterns are driven by stochastic processes, or alternatively, are consequence of highly variable and currently unidentified ecological conditions. In line with this, the investigated ecological parameters did not affect the fitness-related physiological traits differently in both morphs. In the second part of the study, we aimed at identifying trade-offs between fitness-related physiological traits that may contribute to the local maintenance of both colour morphs by defining alternative phenotypic optima, and test the spatial consistency of such trade-off patterns. The female morph with higher levels of phenoloxidase activity had a lower thorax protein content, and vice versa, suggesting a trade-off between investments in immune function and in flight muscles. This physiological trade-off was consistent across the geographical scale studied and supports widespread correlational selection, possibly driven by male harassment, favouring alternative trait combinations in both female morphs.

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“…Thus, natural selection often limits the degree of sexual dimorphism (Endler 1980(Endler , 1983. There can also be ecological causation for sexual dimorphism; in some cases, sexual dimorphism can arise or be maintained because of ecological differences between the sexes (Slatkin 1984;Shine 1989;Cooper 2010). Thus, the form and degree of sexual dimorphism are shaped by both sexual selection and natural selection (Endler 1983;Andersson 1994;Kotiaho et al 1998;Stuart-Fox and Ord 2004).…”

Section: Introductionmentioning

confidence: 99%

Thermoregulation as an Alternate Function of the Sexually Dimorphic Fiddler Crab Claw

Darnell

Munguia

2011

The American Naturalist

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. abstract: Fiddler crabs are highly sexually dimorphic. Males possess one small (minor) feeding claw and one greatly enlarged (major) claw; females possess two small claws. The major claw is used to attract mates and for burrow defense, but it is costly for the male to possess. We tested the hypothesis that the major claw also functions as a thermoregulatory structure, a function that would allow males to spend a greater amount of time at the surface, foraging and attracting potential mates. Fiddler crabs Uca panacea were exposed to a source of radiant heat and body temperatures were monitored.Four groups of crabs were tested: intact males, males with the minor claw removed, males with the major claw removed, and females. The body temperatures of males without the major claw increased more rapidly and reached higher values than did those of males with the major claw intact, but the results from these animals were similar to those of females. These results support the hypothesized thermoregulatory function of the major claw. The major claw may function as a heat sink, transferring heat away from the body and dissipating it into the air. Enhanced thermoregulatory ability provided by the major claw may partially ameliorate the energetic costs of possessing such a large claw.

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Ecology of Sexual Dimorphism and Clinal Variation of Coloration in a Damselfly

Cited by 55 publications

References 35 publications

Morph-specific and sex-specific temperature effects on morphology in the colour polymorphic damselfly Ischnura elegans

Morph-specific and sex-specific temperature effects on morphology in the colour polymorphic damselfly Ischnura elegans

Biogeographical Survey Identifies Consistent Alternative Physiological Optima and a Minor Role for Environmental Drivers in Maintaining a Polymorphism

Thermoregulation as an Alternate Function of the Sexually Dimorphic Fiddler Crab Claw

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