The Evolution of Threshold Traits in Animals

Roff, Derek A.

doi:10.1086/419266

Cited by 375 publications

(388 citation statements)

References 266 publications

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“…Transcription profiles of alternative male life history N. Aubin-Horth and others 1659 of the continuous variation found in many internal and external traits relevant to this kind of developmental plasticity (Roff 1996;Nijhout 2003;West-Eberhard 2003), the developmental trajectories at both the molecular and physiological levels nonetheless produce two discrete and canalized alternative phenotypes instead of a continuous spectrum. Surprisingly, the cluster analysis showed that brain gene expression profiles of sneaker males were more similar to those of immature females than immature males.…”

Section: Resultsmentioning

confidence: 99%

Alternative life histories shape brain gene expression profiles in males of the same population

et al. 2005

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Atlantic salmon (Salmo salar) undergo spectacular marine migrations before homing to spawn in natal rivers. However, males that grow fastest early in life can adopt an alternative 'sneaker' tactic by maturing earlier at greatly reduced size without leaving freshwater. While the ultimate evolutionary causes have been well studied, virtually nothing is known about the molecular bases of this developmental plasticity. We investigate the nature and extent of coordinated molecular changes that accompany such a fundamental transformation by comparing the brain transcription profiles of wild mature sneaker males to age-matched immature males (future large anadromous males) and immature females. Of the ca. 3000 genes surveyed, 15% are differentially expressed in the brains of the two male types. These genes are involved in a wide range of processes, including growth, reproduction and neural plasticity. Interestingly, despite the potential for wide variation in gene expression profiles among individuals sampled in nature, consistent patterns of gene expression were found for individuals of the same reproductive tactic. Notably, gene expression patterns in immature males were different both from immature females and sneakers, indicating that delayed maturation and sea migration by immature males, the 'default' life cycle, may actually result from an active inhibition of development into a sneaker.

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Section: Resultsmentioning

confidence: 99%

Alternative life histories shape brain gene expression profiles in males of the same population

et al. 2005

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“…The maintenance of phenotypic plasticity has been largely attributed to spatially and/or temporally heterogeneous environments (e.g., reviews by Schlichting 1986;West-Eberhard 1989, 2003Thompson 1991;Stearns 1992;Scheiner 1993;Via et al 1995;Roff 1996;Schlichting and Pigliucci 1998;DeWitt et al 1998). In the case of facultative paedomorphosis, environmental heterogeneity includes both between-year variation within a single pond and within-year variation across ponds.…”

Section: Facultative Paedomorphosis and The Evolution Of Phenotypic Vmentioning

confidence: 99%

“…Environmentally-cued polymorphisms (polyphenisms), which occur when discretely different phenotypes develop from genotype by environment interactions, provide excellent opportunities for understanding the mechanisms producing and maintaining phenotypic variation and plasticity (West-Eberhard 1986, 2003Hazel et al 1990Hazel et al , 2004Scheiner 1993;Roff 1996;Relyea 2002;Tomkins and Hazel 2007). Polyphenisms provide model systems for the study of phenotypic variation because: (1) the trait of interest has a direct environmental component; (2) alternative phenotypes are often distinct and easily distinguished; and (3) they are likely to be a direct result of selection (Caswell 1983;Smith-Gill 1983).…”

Section: Introductionmentioning

confidence: 99%

“…The expression of each morph is considered to be a response to the individual's expected success in the aquatic versus terrestrial environment (Wilbur and Collins 1973). Facultative paedomorphosis is characterized as an environmental threshold trait, i.e., there is genetic variation with an environmental trigger (Harris 1987;Harris et al 1990;Roff 1996), and there is considerable support for the hypothesis that the origin and maintenance of facultative paedomorphosis is a result of selection (reviewed in Whiteman 1994;Denoël et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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Larval growth in polyphenic salamanders: making the best of a bad lot

et al. 2011

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Polyphenisms are excellent models for studying phenotypic variation, yet few studies have focused on natural populations. Facultative paedomorphosis is a polyphenism in which salamanders either metamorphose or retain their larval morphology and eventually become paedomorphic. Paedomorphosis can result from selection for capitalizing on favorable aquatic habitats (paedomorph advantage), but could also be a default strategy under poor aquatic conditions (best of a bad lot). We tested these alternatives by quantifying how the developmental environment influences the ontogeny of wild Arizona tiger salamanders (Ambystoma tigrinum nebulosum). Most paedomorphs in our study population arose from slow-growing larvae that developed under high density and size-structured conditions (best of a bad lot), although a few faster-growing larvae also became paedomorphic (paedomorph advantage). Males were more likely to become paedomorphs than females and did so under a greater range of body sizes than females, signifying a critical role for gender in this polyphenism. Our results emphasize that the same phenotype can be adaptive under different environmental and genetic contexts and that studies of phenotypic variation should consider multiple mechanisms of morph production.

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“…Fecundity in fish tends to be correlated with individual length and weight, rather than age [3]. Finally, understanding how a species' spawning time responds to environmental variation is necessary for the proper management of a species [16].…”

Section: Introductionmentioning

confidence: 99%

Reproductive characteristics of Ancherythroculter nigrocauda, an endemic fish in the upper Yangtze River, China

et al. 2013

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Knowledge on the reproductive biology of fishes is critical for understanding a species' life history and devising appropriate management strategies. Anthropogenic forces, such as damming and overfishing, threaten fishes endemic to the upper Yangtze River. We conducted a study on the reproductive biology of an endemic species, Ancherythroculter nigrocauda in order to provide information on the life history of this species and to assist in its conservation. From July 2011 to June 2012, a total of 417 fishes were captured via monthly sampling by fishermen in the Longxi River, a tributary in the upper Yangtze River. Although the female-male ratio was 1:1.03, females were predominantly larger in body size. Gonad somatic indices and oocyte diameter distribution showed that the spawning period of A. nigrocauda in the Longxi River ranged from April to August, with the peak in April. Body length at 50 % sexual maturity of A. nigrocauda was estimated to be 125 and 106 mm for females and males, respectively. Absolute fecundity of A. nigrocauda varied between 11,300 and 504,630 eggs, with the mean of 162,377 eggs. In conclusion, A. nigrocauda mature early, spawn once, and are highly fecund, all of which are consistent with an r-selected life history. It is recommended that a moratorium on fishing this species be enacted and the culture of this species be continued.

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The Evolution of Threshold Traits in Animals

Cited by 375 publications

References 266 publications

Alternative life histories shape brain gene expression profiles in males of the same population

Alternative life histories shape brain gene expression profiles in males of the same population

Larval growth in polyphenic salamanders: making the best of a bad lot

Reproductive characteristics of Ancherythroculter nigrocauda, an endemic fish in the upper Yangtze River, China

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