Relationships between glucocorticoids and infection with Batrachochytrium dendrobatidis in three amphibian species

Using dermal glucocorticoids to determine the effects of disease and environment on the critically endangered Wyoming toad

“… Gabor et al (2015) demonstrated an association between GCs and vulnerability to Bd infection in tadpoles and that GCs are affected by the aggressiveness of the infection. However, Hammond et al (2020) found no relationship between Bd infection and salivary corticosterone in adults of two ranid species, and a context-dependent association in a third species in which Bd -infected individuals had lower baseline (field) and induced (captive) corticosterone than uninfected frogs, with captive frogs having greater corticosterone than wild frogs.…”

“…In juvenile American toads, exogenous corticosterone enhanced resistance, but not their tolerance to Bd ( Murone et al , 2016 ). In adults, previous studies have found a positive relationship between plasma ( Plethodon shermanii , Fonner et al , 2017 ; Litoria caerulea , Peterson et al , 2013 ) and urinary (Stoney Creek frog, Kindermann et al , 2012 , 2017 ) corticosterone and Bd status ( Hammond et al , 2020 ). Here, we did not find any significant relationship between Bd status and dermal cortisol concentrations in reintroduced Wyoming toads.…”

“…Bd has been implicated in mass die-offs of naïve amphibian populations ( Crawford et al , 2012 ; Olson et al , 2013 ). Previous research has investigated the relationship between Bd and GC production in tadpoles and juveniles and found, most commonly, a positive relationship (six of ten; summarized in Hammond et al , 2020 ). For example, two species of Alytes tadpoles had higher urinary corticosterone when Bd + ( Gabor et al , 2013 ).…”

“…This approach may be well suited for aquatic larvae, semi-aquatic or fully aquatic amphibians, but less so for terrestrial species such as toads. Another non-invasive sampling technique, which might be better applicable to field research, is measuring GCs in saliva ( Rana clamitans and R. pipiens ; Hammond et al , 2018 , 2020 ).…”

Beyond corticosterone: The acute stress response increases DNA damage in house sparrows

“…The vertebrate acute stress response—characterized by the activation of the sympathetic nervous and glucocorticoid systems—has long been a focus of studies that seek to understand how organisms cope with unpredictable events in their environments (Romero & Wingfield, 2016). The short‐term increases in heart rate (e.g., Fischer, Franco, & Romero, 2016; Nephew & Romero, 2003) and glucocorticoids (cortisol and corticosterone [Cort]; Wingfield & Romero, 2001; Wingfield, Vleck, & Moore, 1992) are crucial mechanisms that are classically thought to upregulate essential and downregulate nonessential survival systems (Sapolsky, Romero, & Munck, 2000) and have thus become key biomarkers for identifying an animal exposed to a stressor (e.g., Cockrem, Bahry, & Chowdhury, 2019; Fischer et al, 2016; Fischer, Wright‐Lichter, & Romero, 2018; Hammond, Blackwood, Shablin, & Richards‐Zawacki, 2020; Nephew, Kahn, & Romero, 2003; Pusch, Bentz, Becker, & Navara, 2018). Recently, however, increasing evidence suggests that these biomarkers lack reliability.…”