Lack of response to pond desiccation by eggs and tadpoles of the Yungas Red-belly Toad (Melanophryniscus rubriventris) in an unpredictable environment

Abstract

Anuran amphibians that breed in ephemeral ponds of unpredictable environments have mechanisms to tolerate or avoid associated risks of egg and tadpole mortality, such as selection of oviposition sites, plasticity in larval development, and resistance of eggs to desiccation. The Red-belly Toad Melanophryniscus rubriventris (Vellard 1947) breeds in temporary ponds in the Andean Yungas under unpredictable events of flooding and droughts of reproductive sites. To determine whether this species possesses any developmental mechanisms to deal with the environmental conditions, we experimentally evaluated the resistance of eggs subjected to different times of exposure to air and the tadpoles to different levels of pond desiccation. The species has not developed mechanisms of resistance of its eggs or phenotypic plasticity to the recurrent risks of pond desiccation, and mass mortality is a common event. In such a context explosive breeding highly synchronized with rainfall, together with fast larval development, seems to be vitally important at these places where the duration of ponds is short and unpredictable.

Inability of yellow‐bellied toad to accelerate metamorphosis in desiccation conditions

“…Similar time for reaching metamorphosis was also confirmed in a natural populations from Fru ska Gora (personal observations). On the other hand, Melanophryniscus rubriventris (Goldberg et al, 2022), Acris blanchardi (Gordon et al, 2016), Lithobates catesbeianus (Cook et al, 2013), Pseudacris maculata (Amburgey et al, 2012), also did not accelerate their development in response to dry conditions, but, in contrast to our results, pond drying did not affect size and mass at metamorphosis due to modulation of their growth rate to reach similar size and mass at pond drying conditions as in constant water level.…”

“…Phenotypic plasticity is a major source of phenotypic variation and it is a widespread phenomenon in nature (West‐Eberhard, 2003; Whitman & Agrawal, 2009). Many studies on phenotypic plasticity have been carried out in aquatic organisms, especially ones with complex life cycles as amphibians (Charbonnier & Vonesh, 2015; Denver et al, 1998; Goldberg et al, 2022; Johansson & Richter‐Boix, 2013; Lent & Babbitt, 2020).…”

“…Although there are numerous studies on the influence of the larval environment on age and size at the metamorphosis (Enriquez‐Urzelai et al, 2013; Goldberg et al, 2022; Johansson et al, 2005; Lent & Babbitt, 2020; Richter‐Boix et al, 2006; Székely et al, 2017), our knowledge is scarce about this relationship in a species under the high desiccation risk in small temporary ponds which are constantly deteriorating due to habitat loss caused directly/indirectly by global climate changes. In this study, the main aim was to investigate the potential for phenotypic plasticity of life‐history traits of B. variegata which inhabits small mostly rain‐filled ponds which dry out very quickly during the early summer.…”

The role of phenotypic plasticity and corticosterone in coping with pond drying conditions in yellow‐bellied toad (Bombina variegata, Linnaeus 1758) tadpoles

“…Our results supported most of our assumptions: (a) while it was not feasible to measure CORT levels for the H treatment and directly compare CORT levels between the L and H treatments at the metamorphic climax, it remains an indisputable fact that metamorphs from these two treatments exhibit the same developmental time. However, it is important to note that CORT concentrations were different during (Goldberg et al, 2022;Gordon et al, 2016;Hernández-Herrera et al, 2019;Kulkarni et al, 2011Kulkarni et al, , 2017Sinsch et al, 2020;Kijanović at al., 2023), and knowledge of the physiological S4. mechanisms underlying this phenomenon is scarce.…”

Developmental plasticity to desiccation risk in tadpoles of a tropical inselberg specialist

“…Responses to desiccation risk in anurans have been recorded primarily in temperate species with aquatic oviposition and development of aquatic larvae, which generally breed in permanent pools or in pools that predictably dry up annually (Richter-Boix et al, 2011). In contrast, tropical anurans present far more diverse reproductive modes (Duellman and Trueb, 1994;Gomez-Mestre et al, 2012;Liedtke et al, 2022), some of which allow them to cope with much less predictable hydroperiods in some water bodies (Goldberg et al, 2022). For example, it is common to find species with entirely terrestrial development, or with tadpoles developing in small phytotelmata, or in foam nests (Nunes-de-Almeida et al, 2021), all of which can represent a risk of desiccation to the larvae.…”