What do stable isotopes tell us about the trophic ecology of Thamnodynastes hypoconia (Serpentes: Dipsadidae) in southern Brazil?

Rebelato, Marluci Müller; Winemiller, Kirk O.; Durso, Andrew M.; Tozetti, Alexandro Marques; Camargo, Plínio Barbosa de; Verrastro, Laura

doi:10.1016/j.zool.2020.125812

Cited by 8 publications

(8 citation statements)

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“…The species category is considered a fundamental unit of analysis in biogeography, phylogeography, conservation biology and ecology (Gehara et al, 2017; Rebelato et al, 2020; Ward et al, 2020; Werneck et al, 2015). For understanding the real diversity is pivotal to discern between conspecific lineages and species‐level differentiation because speciation involves a continuous process ranging from intraspecific variation and population subdivision (de Queiroz, 2007).…”

Section: Introductionmentioning

confidence: 99%

Phylogeography and species delimitation of the Neotropical frog complex (Hylidae: Scinax granulatus)

et al. 2022

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Understanding which factors driving the genetic structure, geographic distribution patterns, and divergence of populations/species are of great interest in ecology and evolutionary biology. Phylogeographic and species hypotheses combined to distribution models may elucidate which phenomena drove evolutionary history of the biota of different biomes and ecoregions. Herein, we used distribution, environmental and genetic data to shed light on the evolutionary diversity of the Scinax granulatus complex, exploring the phylogeographic patterns, genetic structure and species boundaries across the Pampa and Southern Atlantic Forest biomes. We recovered four mitochondrial lineages which correspond to two putative species within the S. granulatus complex. We used genetic data to define species hypothesis with three discovery methods: bGMYC, bPTP and ASAP, and two delimitation approaches: BPP and BPP + gdi. We validated the species boundaries, confirming the differentiation of Scinax sp. lineage D from Atlantic Forest lowlands habitats, based on genetic data, ecological divergence and monophyly. Lineage D exhibited niche differentiation from S. granulatus sensu stricto (s.s.) based on distribution and environmental data. The climatic suitability of S. sp. D is defined by thermal variables, while that of S. granulatus s.s. was associated with rainfall. The diversification of the S. granulatus complex began during the Pliocene, but the colonization and divergence of lineages took place more recently during the Pleistocene. This study strongly suggests species-level evolutionary divergence among lineages of S. granulatus complex, and highlights the need to carry out a comprehensive evaluation of diagnostic characters to confirm the lineage D as a distinct species.

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Section: Introductionmentioning

confidence: 99%

Phylogeography and species delimitation of the Neotropical frog complex (Hylidae: Scinax granulatus)

et al. 2022

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“…Assuming a nitrogen trophic discrimination of 2.4‰ for snakes (Rabelato et al, 2020) The largest average difference was observed between the δ 15 N values of the forest and the savanna, approximately 5‰ (Figure 2).…”

Section: Discussionmentioning

confidence: 95%

Stable isotopic composition of Bothrops atrox (common lancehead) in four distinct land covers in eastern Amazonia

Martinez,

de Camargo,

da Silva

et al. 2024

Biotropica

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Since consumers reflect the isotopic composition of an assimilated diet, stable isotopes can be a useful tool to address the feeding ecology of tropical snakes. This is the first study reporting carbon and nitrogen stable isotopic composition of Bothrops atrox (Linnaeus, 1758) living in different landscapes located in the lower Amazon river, encompassing four main natural landscapes of the Amazon: old‐growth forests, várzeas (flooded forests), savannas, and pastures. Our null hypothesis is that the δ13C of forest specimens of B.atrox is more negative because forests are dominated by C3 plants, while C4 plants are common in the other landscapes. On the other hand, δ15N of forest specimens should be more positive, since the δ15N of old‐growth forests are higher than plants of savanna, várzea, and pastures. Confirming our hypothesis, the δ13C of B. atrox scales of the Tapajós National Forest was approximate −25‰ to −24‰, increased to approximately −23.5‰ to −23.0‰ in the savanna and pasture, and to −21‰ in the várzea, showing an increased contribution of C4‐derived carbon. Some specimens of B. atrox had δ15N as high as 18‰, which is much higher than the average δ15N of the snake's prey (7‰), confirming the apex position of B. atrox in the Amazon region. The δ15N values of the forest specimens were 5‰ higher than the savanna specimens, and this difference decreased to 3‰ between the forest and the pasture, and the várzea specimens. Finally, there were not large differences between δ15N values of livers and scales in any of the landscapes, suggesting a constant diet through time, and reinforcing the possibility of the use of snake's scale as a less invasive and non‐lethal tissue to analyze.Abstract in Portuguese is available with online material.

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“…Comparisons of absolute values between insular and mainland populations throughout Florida and may be the result of other ecological factors other than diet such as geology, soil type, or plant community. Previous studies of trophic niche in piscivorous snakes have reported a wide range of stable isotope values (Willson et al ., 2010; Brischoux et al ., 2011; Carter, 2015; Perkins et al ., 2020; Rebelato et al ., 2020). The isotopic signature of insular cottonmouths from this study (range: δ 13 C = –24.04 to –16.29, δ 15 N = 10.66 to 19.98) do show some overlap with two species of sea krait ( Laticauda laticauda, L. saintgironsi ) that feed on anguilliform fish in New Caledonia (range: δ 13 C ~ –18.0 to –10.0, δ 15 N ~ 9.0 to 12.0) (Brischoux et al ., 2011), but it is not likely that absolute values are generalizable across fish‐eating populations of snakes.…”

Section: Discussionmentioning

confidence: 99%

“…Probability estimates of the relative contribution of each prey type assimilated by cottonmouth snakes were calculated using Bayesian isotopic mixing models and the SIMMR package that incorporate elemental source concentrations of prey items (Parnell et al ., 2013). We tested the sensitivity of our mixed model to a range of trophic enrichment factor (TEF) means and variances based on literature averages (see review by Post, 2002; Pilgrim, 2005) and values similar to those used in studies involving snakes (Durso & Mullin, 2017; Rebelato et al ., 2020). The TEF is the difference between the stable isotope ratios of a consumer and its food and is necessary to accurately inform trophic mixing models.…”

Section: Methodsmentioning

confidence: 99%

Trophic niche and home range of an insular pit viper following loss of food resources

Sandfoss

McCue²,

Lillywhite

2021

Journal of Zoology

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Investigations of the response of wild populations to natural ecological disturbances can provide insights into the ability of animals to respond to ever‐increasing and intensifying stressors. Seahorse Key is a continental island in the Gulf of Mexico that has been an important rookery site for several species of colonially nesting waterbirds. Resident cottonmouth snakes, Agkistrodon conanti, feed heavily on fish carrion provided by nesting waterbirds. Unexpectedly in 2015, the entire waterbird colony abandoned Seahorse Key and has not returned since. We used stable isotopes and radio‐telemetry to test hypotheses related to the response of the trophic niche and size of home range of insular cottonmouths following the loss of bird‐provided food resources. We found that stable isotope values of carbon (δ13C) decreased while nitrogen (δ15N) values increased between the pre‐ (n = 188) and post‐abandonment (n = 48) periods. The observed changes in stable isotope values correspond to a reduction in feeding on marine fish to terrestrially derived food resources and were also affected by body size and age class. Home range calculated from snakes tracked using radio‐telemetry showed no significant changes between pre‐ and post‐abandonment periods. These data corroborate earlier studies to indicate that cottonmouths on Seahorse Key have not effectively compensated for sudden substantial loss of food resources. This insight has implications for the conservation and management of populations with episodic components of food webs, especially in relation to ecological disturbance.

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What do stable isotopes tell us about the trophic ecology of Thamnodynastes hypoconia (Serpentes: Dipsadidae) in southern Brazil?

Cited by 8 publications

References 77 publications

Phylogeography and species delimitation of the Neotropical frog complex (Hylidae: Scinax granulatus)

Phylogeography and species delimitation of the Neotropical frog complex (Hylidae: Scinax granulatus)

Stable isotopic composition of Bothrops atrox (common lancehead) in four distinct land covers in eastern Amazonia

Trophic niche and home range of an insular pit viper following loss of food resources

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