Fluctuating asymmetry in relation to indices of quality and fitness in the damselfly, Enallagmaebrium (Hagen)

Leung, Brian; Forbes, Mark R.

doi:10.1007/s004420050182

Cited by 70 publications

(51 citation statements)

References 30 publications

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“…A major point of agreement is that distributions with negative kurtosis (antisymmetry) are not acceptable. A number of recent publications have, in fact, evaluated non-normal distributions (e.g., Øxnevad et al 1995;Leung and Forbes 1997b;Somarakis et al 1997). Following this line of thought, a thorough analysis of the data for both the wild fish and the 25°C fish was completed anyway.…”

Section: Discussionmentioning

confidence: 99%

Physical variability and fluctuating asymmetry in heterozygous and homozygous populations of Rivulus marmoratus

Taylor¹

2001

Can. J. Zool.

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The debate over the influence of heterozygosity and homozygosity on developmental stability is ongoing, and rarely is an animal model found that represents these two genetic states in naturally occurring populations. Rivulus marmoratus (Pisces: Aplocheilidae), a small cyprinodontid fish indigenous to mangrove marshes of the western tropical Atlantic coast, may be an appropriate model. This species is well known as the only self-fertilizing hermaphroditic vertebrate, and populations normally consist of genetically diverse groups of homozygous clones. However, male fish are known from a few populations, and outcrossing has been documented from one area (Belize in Central America) where heterozygosity is the norm. Are there differences in developmental stability, as represented by fluctuating asymmetry (FA) and physical variability, between naturally occurring homozygous and heterozygous populations? Thirty-one meristic and morphometric characters in 180 fish from 10 populations were examined to determine physical variability. In addition, FA and the presence of physical anomalies were analyzed. Belize fish (heterozygous) were compared with eight other (homozygous) populations. To control for possible environmental effects, offspring of two populations (Belize and Florida) were reared at 25°C and similarly analyzed. The FA analyses and variability comparisons revealed no differences between heterozygous and homozygous populations, and the same was true for fish reared at a constant temperature. However, some populations (e.g., Brazil) were more variable than others. These results indicate that coadapted gene complexes may be more important than heterozygosity in canalizing developmental stability in this animal.Résumé : La controverse au sujet de l'influence de l'hétérozygotie et de l'homozygotie sur la stabilité du développe-ment se poursuit et il est difficile de trouver un modèle animal qui puisse représenter les deux conditions génétiques chez des populations naturelles. Rivulus marmoratus (Pisces : Aplocheilidae), un petit poisson cyprinodonte indigène des mangroves de l'Atlantique tropical occidental, est potentiellement un bon modèle. C'est la seule espèce de vertébré hermaphrodite à s'auto-féconder et les populations sont ordinairement constituées de groupes génétiquement diversifiés de clones homozygotes. Cependant, les mâles existent chez quelques populations et des croisements allogames ont pu être réalisés en une région (Bélize, l'Amerique centrale) où l'hétérozygotie est la condition normale. Existe-t-il des différences dans la stabilité du développement, telles que mesurées par l'asymétrie fluctuante et la variabilité physique, entre les populations naturelles homozygotes et hétérozygotes? Trente et une mesures méristiques et morphométriques relevées sur 180 poissons de 10 populations ont permis d'évaluer la variabilité physique. En outre, l'asymétrie fluctuante et la présence d'anomalies physiques ont été analysées. Les poissons du Bélize (hétérozygotes) ont été comparés à ceux de huit autres populati...

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Section: Discussionmentioning

confidence: 99%

Physical variability and fluctuating asymmetry in heterozygous and homozygous populations of Rivulus marmoratus

Taylor¹

2001

Can. J. Zool.

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“…Lower mass at emergence reduces survival during the maturation period in both males and females (e.g. Forbes and Baker 1990;Leung and Forbes 1997). Furthermore, L. sponsa males with a lower than average mass have lower lifetime mating success in this species (R. Stoks unpublished data; see also Banks and Thompson 1985).…”

Section: Discussionmentioning

confidence: 99%

Lethal and sublethal costs of autotomy and predator presence in damselfly larvae

et al. 1999

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We studied the costs of lamellae autotomy with respect to growth and survival of Lestes sponsa damselfly larvae in field experiments. We manipulated predation risk by Aeshna cyanea dragonfly larvae and lamellae status of L. sponsa larvae in field enclosures and compared differences in numbers, size and mass of survivors among treatments. In the absence of a free-ranging A. cyanea larva, about 29% of the L. sponsa larvae died. This was probably due to cannibalism. The presence of a free-ranging A. cyanea reduced larval survival by 68% compared to treatments in which it was absent or not permitted to forage on L. sponsa damselflies. Across all predator treatments, lamellae autotomy reduced survival by about 20%. The mean head width and mass of survivors was lower in the enclosures with a free-ranging A. cyanea compared to the other two predator treatments. This suggested that larvae grew less in the presence of a free-ranging predator, indicating that increased antipredator behaviours were more important in shaping growth responses than reduced population density. Mass, but not head width, of survivors was also reduced after autotomy. The fitness consequences of these effects for the adults may be pronounced. In general, these field data strongly suggest that lamellae autotomy affects population regulation of damselflies.

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“…We used Levene's test to assess changes in variance (Snedecor and Cochran 1989), modified for regression (e.g., Leung and Forbes 1997). Levene's test compares differences in the absolute value of the residuals, using t-test for comparison between groups and regression for continuous variables.…”

Section: Hypothesesmentioning

confidence: 99%

Propagule pressure, Allee effects and the probability of establishment of an invasive species (Bythotrephes longimanus)

2011

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Abstract. Predicting establishment of exotic species is a central goal of invasion biology, and is dependent upon propagule pressure and population processes. We introduced invading spiny water fleas, Bythotrephes longimanus at different propagule pressures into 19 experimental enclosures, following populations over asexual generations, resting egg production, and emergence in the following year. We integrated experimental results with field data to generate a stochastic population model, predicting establishment in relation to propagule pressure and introduction date. Our results suggested that Allee effects are operational at higher densities or smaller volumes than previously predicted, that stochasticity plays an important role in establishment, and demographic stochasticity may be correlated between individuals. Further, our novel theoretical derivations suggest that organisms should modify their sex ratios to reduce Allee effects. The functional form using adaptive sex-ratios was consistent with both mesocosm and field data. Despite the occurrence of Allee effects and stochasticity, there was still no date during the growing season where we predict lakes to be entirely safe from Bythotrephes invasions. A single propagule had approximately a 0.15 establishment probability in our mesocosms, if introduced early in the season; propagule pressures of 10 had . 0.50 probability, regardless of introduction date.Key words: adaptation; Allee effects; exotic species; mesocosm experiment; non-indigenous species; optimality; population dynamics; probability; sex-ratio.

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Fluctuating asymmetry in relation to indices of quality and fitness in the damselfly, Enallagmaebrium (Hagen)

Cited by 70 publications

References 30 publications

Physical variability and fluctuating asymmetry in heterozygous and homozygous populations of <i>Rivulus</i> <i>marmoratus</i>

Physical variability and fluctuating asymmetry in heterozygous and homozygous populations of <i>Rivulus</i> <i>marmoratus</i>

Lethal and sublethal costs of autotomy and predator presence in damselfly larvae

Propagule pressure, Allee effects and the probability of establishment of an invasive species (Bythotrephes longimanus)

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