The Relationship of Water Economy to Terrestrialism in Amphibians

Thorson, Thomas B.

doi:10.2307/1931435

Cited by 151 publications

(107 citation statements)

References 16 publications

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“…Ambientes que sofreram alterações antrópi-cas são caracterizados por vegetação mais esparsa e estão sujeitos a maior exposição solar, menor umidade e temperaturas mais elevadas quando comparados a áreas de mata preservada, com vegetação alta, densa e dossel fechado (Sexton et al 1964, Crump 1971, Inger & Colwell 1977, Pough et al 1977. As características particulares de cada ambiente em relação a estes fatores, possivelmente determinam e limitam a distribuição das espécies presentes no PECB, uma vez que diferentes espécies de anuros respondem diferencialmente às condições ambientais, apresentando diferentes taxas de crescimento e desenvolvimento, além de exibirem graus distintos de resistência e tolerância a perda de água (e.g., Thorson & Svihla 1943, Thorson 1955, Bellis 1962, Heatwole et al 1968, Crump 1971, Snyder & Weathers 1975, Pough et al 1977, Christian et al 1988, Giaretta et al 1997, Werner & Glennemeier 1999, Halverson et al 2003, Felix et al 2004. Espécies do gênero Chaunus, por exemplo, toleram maiores níveis de perda d'água em relação a espécies de outros grupos de anuros (cf.…”

Section: Discussionunclassified

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Composição e diversidade de anfíbios anuros em dois ambientes de Mata Atlântica no Parque Estadual Carlos Botelho, São Paulo, sudeste do Brasil

2007

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The Atlantic Forest is characterized by its high species richness and endemism, and is one of the 25 hotspots of biodiversity around the world. We present information on composition and diversity of anuran amphibians in two environments with different degrees of disturbance in Parque Estadual Carlos Botelho, São Paulo state, an area of Atlantic Rain Forest in southeastern Brazil. We sampled an artificial pond in a disturbed area and a pond in a preserved area by audio sampling and incidental encounters, in 36 nights in each habitat. We compared the species composition, richness, dominance, and relative abundance between the two habitats. Despite distant only ca. 400 m, we recorded only two species in common between the two habitats. We recorded in the disturbed area 10 species (N = 518) with 46.7% of dominance of Hypsiboas albopunctatus; and in the preserved habitat we recorded 11 species (N = 656) with 36.0% of dominance of Dendropsophus giesleri. Richness was not significantly different between the habitats. The estimated dominance by rarefaction in the preserved habitat was significantly lower than that in the disturbed habitat. The capability of some species populations in colonizing the disturbed habitat, the distinct physiological tolerance among species, and the dependence on specific microhabitats for reproduction are possible factors related to the observed patterns. We suggest that additional alterations of the Atlantic Forest cover inside the reserve might result in a decrease of alpha-diversity by eliminating forest dependent species, as well as a consequently increase in beta-diversity by the colonization of open area species that are ecologically more generalist. The slightly higher richness and mainly lower dominance observed in the preserved area indicate it is the habitat with higher species diversity. Thus, the presence of old-growth and/or conserved forests in the reserve is essential to maintain the local anuran diversity. A Mata Atlântica é caracterizada pela elevada riqueza e endemismo de espécies, e é um dos 25 hotspots de biodiversidade mundiais. Apresentamos informações sobre a composição e diversidade de espécies de anfíbios anuros em dois ambientes com diferentes graus de perturbação no Parque Estadual Carlos Botelho, SP, uma área de Mata Atlântica no sudeste do Brasil. Amostramos um açude em área alterada e uma lagoa em área preservada, através de procura auditiva e encontros ocasionais em 36 noites de observação em cada ambiente. As duas áreas foram comparadas em relação à composição, riqueza, dominância e abundância relativa de espécies. Apesar de próximos, cerca de 400 m, apenas duas espécies foram comuns aos dois ambientes. Na área alterada registramos 10 espécies (N = 518) e dominância de 46,7% de Hypsiboas albopunctatus, e na área preservada 11 espécies (N = 656) e dominância de 36,0% de Dendropsophus giesleri. A riqueza não foi significativamente diferente nos dois ambientes. A dominância estimada por rarefação na área preservada foi significativamente menor em

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Section: Discussionunclassified

“…Espécies do gênero Chaunus, por exemplo, toleram maiores níveis de perda d'água em relação a espécies de outros grupos de anuros (cf. Thorson & Svihla 1943, Thorson 1955. Isto pode explicar em parte a presença e a abundância das duas espécies deste gênero na área alterada, que não foram registradas na área preservada.…”

Section: Discussionunclassified

Composição e diversidade de anfíbios anuros em dois ambientes de Mata Atlântica no Parque Estadual Carlos Botelho, São Paulo, sudeste do Brasil

2007

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“…Thorson (1955Thorson ( , 1964 reported that extracellular fluid volume (ECFV) was correlated with degree ot terrestriality. Hillman (1980) has shown that the more dehydration tolerant species have larger blood volumes than the less tolerant aquatic forms.…”

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confidence: 99%

The contribution of the lymph hearts in compensation for acute hypovolemic stress in the toad Bufo marinus

Baustian¹

2000

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The Marine Toad Bufo marinus was used as a model for an investigation of the rate and volume pumping capacity of the amphibian lymph heart. B. marinus is a widely studied terrestrial toad which would be expected to experience a hypovolemic stress as a consequence of evaporative water loss when it is away from water.Currently published data on the role of the lymphatic system in amphibians are inadequate and contradictory. Estimates of the rate of formation of lymph and the role of the lymph hearts in returning this fluid to the circulation are not based on actual volume determinations :2 but rather estimates derived from changes in hematocrit using published values of plasma and blood volume. The lymph hearts are known to be vital to the maintainence of normal fluid compartment physiology and to increase their rate of activity during episodes of hypovolemic stress.Yet, significant redistribution of body fluids following hemorrage appears to occur in animals without lymph hearts.In this study, plasma and blood volumes were determined by the dye dilution technique using injected Evan's blue dye to label the plasma.Eight intact and 6 animals with their lymph hearts destroyed were hemorrhaged to 78% and 75% of their initial blood volumes, respectively.Changes in blood volume were measured following the hemorrhage by analysis of Evan's blue washout and hemodilution.

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“…Frogs used in the present study were considerably smaller than those used by Hillman, however, and tolerance to water loss appears to be greater for frogs of lower body mass (Thorson, 1955 Drug concentrations used in this study were within the range of those used in previous experiments with amphibians. Hillman (1982) found that dosages of propranolol in excess of 0.01 mg/kg produced a significant reduction in maximal heart rate in Scaphiopus intermontanus.…”

Section: Discussionmentioning

confidence: 41%

“…Adaptation to terrestrial environments in amphibians does not usually involve mechanisms to reduce water loss, but rather increased tolerance to water loss. Among anuran amphibians (frogs and toads) there is a general positive correlation between dehydration tolerance and the terrestriality of the species (Thorson and Svihla, 1943;Thorson, 1955).…”

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confidence: 99%

The significance of hypovolemia in dehydrational death in anurans

Kimmel¹

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The Relationship of Water Economy to Terrestrialism in Amphibians

Cited by 151 publications

References 16 publications

Composição e diversidade de anfíbios anuros em dois ambientes de Mata Atlântica no Parque Estadual Carlos Botelho, São Paulo, sudeste do Brasil

Composição e diversidade de anfíbios anuros em dois ambientes de Mata Atlântica no Parque Estadual Carlos Botelho, São Paulo, sudeste do Brasil

The contribution of the lymph hearts in compensation for acute hypovolemic stress in the toad Bufo marinus

The significance of hypovolemia in dehydrational death in anurans

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