Adaptation or exaptation? An experimental test of hypotheses on the origin of salinity tolerance in<i>Bufo calamita</i>

Gómez-Mestre, Iván; Tejedo, Miguel

doi:10.1111/j.1420-9101.2004.00878.x

Cited by 28 publications

(24 citation statements)

References 70 publications

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“…In southeast Spain, populations of the water frog, Pelophylax perezi, from aquatic environments with high levels of nitrogen pollution showed higher survival and larger final size than populations from less polluted environments (Egea-Serrano et al 2009). Such observations can be explained by variations between populations' genetic tolerance to environmental stressors (Semlitsch et al 2000;Gomez-Mestre and Tejedo 2005;Marquis et al 2009). …”

Section: Introductionmentioning

confidence: 95%

Intra-specific variation in nitrate tolerance in tadpoles of the Natterjack toad

et al. 2011

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Anthropogenic sources of nitrogen that pollute bodies of water can have toxic and sub-lethal effects on amphibians. It has been hypothesized that such exposure may promote local adaptation, that is, selection for higher tolerance in individuals in populations exposed to pollutants. We tested this hypothesis with respect to the Natterjack toad (Bufo calamita Laurenti, 1768), by comparing the nitrate dose response of tadpoles from eight populations (doses: 0, 50, 100, 500 and 1000 mg/l nitrate) from relatively unpolluted and intensively farmed environments. We evaluated the effect of nitrate exposure by observing the behavior (movements) of tadpoles exposed to different concentrations of nitrates. Exposure to high nitrate levels did not cause tadpole mortality in the populations used in our experiments; however, we did observe changes in activity for all populations, with these changes being either dose-related responses (decreased activity after exposure to 500 or 1000 mg/l), or more complex responses (increased activity when exposed to 50 or 100 mg/l nitrate, followed by decreased activity at higher concentrations). Natterjack toad tadpoles exhibited variable behavioural responses among the tested populations. Although these populations were selected on the basis of their potential agrochemical contamination, the observed variation in population tolerance was not related to the parameters used to estimate this contamination in these breeding sites. Possible explanations for this apparent lack of local adaptation in B. calamita tadpoles include inadequate estimates of the toads' actual nitrate exposure in the field, and the biological characteristics of B. calamita, which may limit the effects of exposure or favor phenotypic plasticity.

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Section: Introductionmentioning

confidence: 95%

Intra-specific variation in nitrate tolerance in tadpoles of the Natterjack toad

et al. 2011

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“…Drier substrates decrease postmetamorphic growth rate, enhance burying behavior and decrease foraging activity and efficiency in B. calamita (Gomez-Mestre and Tejedo, 2005). Likewise, field reciprocal transplant experiments on P. cultripes juveniles between sandy and granite-schist soil environments show reduced growth in the sandy environment (Tejedo and Marangoni, unpublished data).…”

Section: Growing On Sandy Soilsmentioning

confidence: 96%

“…In support of this idea, some authors have found a positive correlation between body size and aridity in some frog species (Nevo, 1973;Rosso et al, 2004). Alternatively, by imposing high energetic costs of maintaining water balance, sandy substrates may constrain growth by reducing activity or foraging efficiency (Rohr and Madison, 2003;Gomez-Mestre and Tejedo, 2005) or, indirectly, by limiting availability of food resources (Rohr, 1997;Bronikowski and Arnold, 1999;Tracy, 1999). The observed dwarfism associated to sandy soils in Doñana contradicts the expected morpho-functional advantage of large size in desiccating substrates and therefore seems to be nonadaptive.…”

Section: Growing On Sandy Soilsmentioning

confidence: 96%

Extreme reduction in body size and reproductive output associated with sandy substrates in two anuran species

2008

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Abstract. Geographic variation in body size and reproductive traits has been reported in a wide range of organisms, including amphibians. Most studies have focused on latitudinal and/or altitudinal variation where differences in temperature and duration of the growing season are the main causes for population divergence. We describe a steep variation in body size and reproductive traits in two anuran species in southwestern Spain, associated with changes in the geological substrate. Pelobates cultripes and Bufo calamita (= Epidalea calamita) drastically reduced their size (a 71.6% and 76.1% reduction in body mass for P. cultripes and B. calamita, respectively) in just about 60 km. This extreme size reduction was more pronounced at the boundary between two different geological substrates (hercinic and sandy soil). Mean clutch mass, egg size, and clutch size were all smaller in B. calamita populations in the sandy environment. Likewise, clutch mass and egg size were both smaller in sandy P. cultripes populations. We observed a negative correlation between size-adjusted fecundity and egg size for both species, suggesting the existence of a reproductive trade-off that could explain the differences in reproductive allocation between populations and species. In P. cultripes, small-bodied populations had relatively higher fecundities and smaller eggs than large-bodied ones, whereas in B. calamita populations from the sandy area we found both populations with high fecundity and small eggs, and populations with low fecundity and large eggs. Common environmental effects associated with the sandy substrate produce a similar reduction in size in both toad species.

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“…It is possible, however, that salamanders in dry treatments spent an equal time out of the burrow but chose not to feed. Gomez-Mestre and Tejedo [81] found that Bufo calamita in dry environments were also less efficient at catching prey. The prey in our experiment was confined to a small container, so we assume that salamanders in both low and high moisture treatments were equally efficient at catching the prey.…”

Section: Discussionmentioning

confidence: 99%

Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander

et al. 2018

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For organisms with complex life cycles, conditions experienced during early life stages may constrain later growth and survival. Conversely, compensatory mechanisms may attenuate negative effects from early life stages. We used the spotted salamander, Ambystoma maculatum, to test how aquatic larval density and terrestrial moisture influence juvenile growth, food intake, evaporative water loss and water reuptake rates, and corticosterone levels. We conducted an outdoor mesocosm experiment to manipulate larval density and transferred metamorphosed salamanders into low and high terrestrial moisture treatments in laboratory terrariums. After the larval stage, high-density salamanders were significantly smaller and had higher corticosterone release rates than those from low-density treatments. Salamanders in the low terrestrial moisture treatment consumed fewer roaches, had lower mass-specific growth rates, higher water reuptake, and higher corticosterone release rates than salamanders in high terrestrial moisture treatments. Across moisture treatments, smaller salamanders had higher mass-specific growth rates than larger salamanders. Our results suggest that salamanders can partially compensate for competition in the larval aquatic habitat with increased growth as juveniles, but this response is dependent on terrestrial habitat quality. Thus, the persistence of early life stage effects can be an important, yet context-dependent, component of amphibian life cycles.

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Adaptation or exaptation? An experimental test of hypotheses on the origin of salinity tolerance inBufo calamita

Cited by 28 publications

References 70 publications

Intra-specific variation in nitrate tolerance in tadpoles of the Natterjack toad

Intra-specific variation in nitrate tolerance in tadpoles of the Natterjack toad

Extreme reduction in body size and reproductive output associated with sandy substrates in two anuran species

Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander

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