The Role of Prey in Controlling Expression of a Trophic Polymorphism in Ambystoma tigrinum nebulosum

Loeb, Michael L. G.; Collins, James P.; Maret, Timothy J.

doi:10.2307/2389898

Cited by 37 publications

(33 citation statements)

References 16 publications

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“…The size of the head is probably related to prey capture in salamanders (Zaret 1980), and polymorphisms in many other species have a relatively straightforward adaptive interpretation because plasticity produces a close association between trophic morphology and a locally available resource (Collins and Cheek 1983, Walls et al 1993, Loeb et al 1994, Nishihara 1996. We propose that predator-induced variation in Triturus head shape may also be adaptive because it improves feeding efficiency in both environments.…”

Section: Adaptive Plasticity: Environmental Heterogeneity and Individmentioning

confidence: 86%

Predator-Induced Phenotypic Plasticity in Larval Newts: Trade-Offs, Selection, and Variation in Nature

Buskirk¹,

Schmidt²

2000

Ecology

138

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Phenotypic plasticity has important ecological consequences because the strengths of species interactions can change with the behavior and morphology of interacting individuals. Evolutionary studies of plasticity can predict conditions under which shifts in phenotypes will occur and, therefore, may modify species interactions. We studied evolutionary mechanisms maintaining an induced response to predators in Triturus newt larvae, which are among many taxa in freshwater habitats exhibiting predator-induced plasticity. When exposed to caged (nonlethal) Aeshna dragonfly larvae, newts of two species (T. alpestris and T. helveticus) spent more time hiding in the leaf litter, had darker pigmentation in the tail fin, and developed larger heads and larger tails relative to their body size, in comparison with newts in predator-free ponds. The two phenotypes faced a performance trade-off across environments with and without odonates: the predator-induced phenotype survived twice as well as the no-predator phenotype when exposed to free dragonflies, but the predator-induced phenotype of both species grew more slowly until just before metamorphosis. For Triturus alpestris, a direct comparison of performance between phenotypes was complicated because predator-induced newts emerged later in the summer but at a larger body size. Nonrandom mortality imposed by hunting dragonflies caused selection favoring increasing tail size, but we found no selection on specific traits in predator-free ponds. Head shape was not subject to selection in either environment; we suspect that head shape is involved in consuming different prey in the presence and absence of predators and is unrelated to predator escape. Triturus in 25 natural populations from which we collected quantitative samples in 1997 and 1998 exhibited extreme spatial variation in predation regime (density of large predators ranged from 0 to 24 individuals/m2). Variation among populations in head shape was exactly as predicted by experimental results (Triturus of both species had relatively large heads when exposed to predators), but results for tail shape were consistent with the experiments in only one of the two years. The evolutionary mechanisms maintaining plasticity in Triturus and other amphibian larvae should apply to many organisms inhabiting freshwater ponds, so trait-mediated indirect effects seem especially likely to occur in these habitats. Abstract. Phenotypic plasticity has important ecological consequences because the strengths of species interactions can change with the behavior and morphology of interacting individuals. Evolutionary studies of plasticity can predict conditions under which shifts in phenotypes will occur and, therefore, may modify species interactions. We studied evolutionary mechanisms maintaining an induced response to predators in Triturus newt larvae, which are among many taxa in freshwater habitats exhibiting predator-induced plasticity. When exposed to caged (nonlethal) Aeshna dragonfly larvae, newts of two species (T. alpestris...

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Section: Adaptive Plasticity: Environmental Heterogeneity and Individmentioning

confidence: 86%

Predator-Induced Phenotypic Plasticity in Larval Newts: Trade-Offs, Selection, and Variation in Nature

Buskirk¹,

Schmidt²

2000

Ecology

138

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“…Eating conspecifics has the advantage of increasing growth rate, but has the disadvantage of increasing exposure to potentially deadly diseases (Pfennig, Loeb & Collins, 1991). Sympatric tadpoles may enhance expression of the cannibal morph, but tadpoles alone cannot induce the morph (Loeb, Collins & Maret, 1993). Multiple variables are clearly affecting expression of cannibalism, suggesting that once a novel phenotype appears in a population, a number of factors must be satisfied if it is to persist.…”

Section: Ecology and The Evolution Of Multiple Morphsmentioning

confidence: 99%

Shaping intraspecific variation: Development, ecology and the evolution of morphology and life history variation in tiger salamanders

1993

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The tiger salamander, Ambystoma tigrinum, is a geographically widespread, morphologically variable, polytipic species. It is among the most variable species of salamanders in morphology and life history with two larval morphs (typical and cannibal) and three adult morphs (metamorphosed, typical branchiate, cannibal branchiate) that vary in frequency between subspecies and between populations within subspecies. We report morphometric evidence suggesting that branchiate cannibals arose through intraspecific change in the onset or timing of development resulting in the wider head and hypertrophied tooth-bearing skull bones characteristic of this phenotype. We also quantified bilateral symmetry of gill raker counts and abnormalities, then evaluated fluctuating asymmetry as a measure of the developmental stability of each morph. There was a significant interaction between fluctuating asymmetry of developmental abnormalities in cannibals and typicals and the locality where they were collected, suggesting that relative stability of each phenotype could vary among populations. While altered timing of developmental events appears to have a role in the evolution and maintenance of morphs, novel phenotypes persist only under favorable ecological conditions. Predictability of the aquatic habitat, genetic variation, kinship, body size, intraspecific competition and predation all affect expression and survival of the morphs in A. tigrinum. This taxon provides an excellent model for understanding the diversity and complexity of developmental and ecological variables controlling the evolution and maintenance of novel phenotypes.

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“…The specific morphology and aggressive behavior of the morph are advantageous for the consumption of large prey such as conspecific larvae or heterospecific anuran larvae, similar to cannibal morphology in the tiger salamander (Ambystoma tigrinum) larvae (Loeb et al 1994;Whiteman et al 2003). Because H. retardatus usually spawns during early spring in ponds created by melting snow, the typical food (macro benthos such as Oligochaeta and Chironomidae) of newly hatched larvae is not always available to the newly hatched larvae.…”

Section: Introductionmentioning

confidence: 99%

Differentiated phenotypic plasticity in larvae of the cannibalistic salamander Hynobius retardatus

Michimae

2006

Behav Ecol Sociobiol

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Alternative phenotypes in natural populations can arise from either genetic polymorphism or an environmentally induced phenotype, that is, polyphenism.Evolutionary models of polyphenism developed by theoretical studies predict that polyphenism is favored when there are environment-dependent fitness trade-offs between alternatives and that the threshold frequency for a facultative switch between alternative phenotypes is adjusted in accordance with different selection regimes. The broad-headed (alternative) larval morph of Hynobius retardatus, which is induced by crowding with conspecifics or heterospecific anuran (Rana pirica) larvae, is a representative example of cannibalistic polyphenism. Morph induction by such proximate factors must reflect evolutionary (conditional frequency-dependent) processes. To clarify the role of frequency-dependent processes in polyphenism, Iinvestigated the occurrence rate of the broad-headed morph under experimental crowding conditions (low conspecific, high conspecific, and high heterospecific densities) using larvae from eight natural populations with different larval densities of conspecifics and heterospecifics, and found interpopulational differences in the expression of the morph. Thus, there is a larval density-dependent equilibrium frequency of the morph in each pond, suggesting that the local switch point for morph induction was modified by selection to produce evolved differences between ponds.The evolution of such interpond differences has three necessary conditions: (1) There are pond-dependent fitness trade-offs between alternatives, (2) The maintenance of the morph is costly, and (3) The presence of conspecific or, especially, heterospecific larvae provides a reliable cue to the receiver. 2Keywords Broad-headed morph · Cannibalistic polyphenism · Phenotypic plasticity · Reaction norm · Salamander.3

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The Role of Prey in Controlling Expression of a Trophic Polymorphism in Ambystoma tigrinum nebulosum

Cited by 37 publications

References 16 publications

Predator-Induced Phenotypic Plasticity in Larval Newts: Trade-Offs, Selection, and Variation in Nature

Predator-Induced Phenotypic Plasticity in Larval Newts: Trade-Offs, Selection, and Variation in Nature

Shaping intraspecific variation: Development, ecology and the evolution of morphology and life history variation in tiger salamanders

Differentiated phenotypic plasticity in larvae of the cannibalistic salamander Hynobius retardatus

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