Spatial distribution and habitat preferences of co-occurring vertebrate species: Case study of an endangered frog and an introduced toad in Fiji.

Thomas, Nunia T.; Morrison, Clare; Winder, Linton; Morley, Craig

doi:10.1071/pc110068

Cited by 10 publications

(18 citation statements)

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“…Seeking refuge following a stressful encounter could be beneficial if the intruder is a visual hunter, but may prove detrimental when the predator is able to enter these substrates. There is empirical evidence that the spatial distributions of the cane toads and Fijian ground frogs on Viwa Island overlap quite significantly [31]. We studied the male ground frogs during breeding thus future studies should investigate whether responses (fearfulness and corticosterone responses) of male frogs are similar outside the breeding season, including their correlation with testosterone [53,54] and body condition [7].…”

Section: Discussionmentioning

confidence: 99%

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Sight of a Predator Induces a Corticosterone Stress Response and Generates Fear in an Amphibian

2013

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Amphibians, like other animals, generate corticosterone or cortisol glucocorticoid responses to stimuli perceived to be threatening. It is generally assumed that the corticosterone response of animals to capture and handling reflects the corticosterone response to stimuli such as the sight of a predator that are thought to be natural stressors. Fijian ground frogs ( Platymantisvitiana ) are preyed upon by the introduced cane toads ( Rhinellamarina ), and we used ground frogs to test the hypothesis that the sight of a predator will induce a corticosterone stress response in an amphibian. Urinary corticosterone metabolite concentrations increased in male ground frogs exposed to the sight of a toad for 1, 3 or 6 h, whereas corticosterone did not change in frogs exposed to another male ground frog, a ball, or when no stimulus was present in the test compartment. The frogs exposed to a toad initially moved towards the stimulus then moved away, whereas frogs exposed to another frog moved towards the test frog and remained closer to the frog than at the start of the test. Tonic immobility (TI) was measured as an index of fearfulness immediately after the test exposure of the frogs to a stimulus. The duration of TI was longer in frogs exposed to a toad than to another frog or to a ball. The results provide novel evidence that the sight of a predator can induce a corticosterone response and lead to increased fearfulness in amphibians. In addition, they show that endemic frogs can recognise an introduced predator as a threat.

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Section: Discussionmentioning

confidence: 99%

“…The endemic ground frog population on Viwa Island are preyed upon by the cane toad ( Rhinellamarina ) [31–33]. Evidence dating back 20 years highlights that cane toads predate upon froglets and juveniles [34].…”

Section: Introductionmentioning

confidence: 99%

Sight of a Predator Induces a Corticosterone Stress Response and Generates Fear in an Amphibian

2013

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“…The stocking density of one adult ground frog to four adult cane toads was based on previously reported abundance estimates for the natural habitat on Viwa Island that the enclosures were built upon (Thomas et al . ). Control enclosures were only stocked with 100 adult ground frogs (50 adult male and 50 adult females).…”

Section: Methodsmentioning

confidence: 97%

“…By using different vegetation communities that influenced habitat choice and hence densities of toads and ground frogs across our study site, it was possible to assess physiological data from ground frogs at naturally occurring high and low cane toad densities (Thomas et al . ).…”

Section: Introductionmentioning

confidence: 97%

Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic

2015

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1. Understanding the mechanisms that afford invasive species their ecological success as important agents of global change is key to addressing their biodiversity impacts. Species invasions that occur on small islands are especially detrimental and suggest that invaders intensify their ecological impacts by exploiting novel ecological functions. However, it remains unknown whether such strong impacts are also a consequence of an invader's indirect effect (e.g. causing physiological stress or reproductive failure) on island species. Therefore, it is valuable to quantify the physiological mechanisms through which invasive species can exert indirect effects on the performance, and ultimately the fitness of island endemics. 2. In this study, we investigated whether the invasive cane toad (Rhinella marina) caused indirect competitive impacts on the endemic Fijian ground frog (Platymantis vitiana) on the small (60 ha) Viwa Island, Fiji. We used large (4 9 10 000 m 2 ), natural and replicated enclosures to monitor ground frog stress hormone levels, reproductive hormone cycle, body condition, breeding and survival in the presence/absence of the cane toad. We conducted monthly sampling to analyse annual patterns in testosterone for males, estradiol and progesterone for females, corticosterone for both sexes and body condition of ground frogs in replicated enclosures or natural habitats with high/low cane toad densities. We also measured survival and reproductive success of ground frogs in enclosures.3. Results showed that in both enclosures and natural habitats with high cane toad densities, ground frogs had a significant reduction in body condition, increased urinary corticosterone metabolites and suppressed sex steroid metabolites. Most importantly, annual field surveys showed significant reduction in ground frog reproductive success (fewer eggs were laid in enclosures with toads present); however, survival was not severely reduced. 4. Our study clearly demonstrated that on small islands, invasive species may exploit broader ecological roles with strong indirect effects that amplify their impacts beyond those seen on continents. Overall, the effects of cane toad competition had the capacity to strongly reduce ground frog reproductive success. We strongly advocate management actions that either minimize invasion or limit the strength of invasive-native species interactions (e.g. through habitat conservation) to prevent further extinctions on islands.

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“…In Arroyo Hornitos there were no records of L, forreri and L. melanonotus, although these species were generally observed in low numbers at other streams during the study. Some studies have reported that these two species are clearly associated with disturbed or open habitats, and with water bodies that have long, stable hydroperiods (Carrasco, 1989;Ford & Scott, 2006;Suazo-Ortuño et al, 2008;Urbina-Cardona, Olivares-Pérez, & Reynoso, 2006;Thomas, Morrison, Winder, & Morley, 2011;Mendenhall et al, 2014). Therefore, it may be that the conserved, seasonally dry forest of Chamela is not an adequate habitat for this species to occur in high numbers.…”

Section: Discussionmentioning

confidence: 96%

Spatial and temporal distribution and microhabitat use of aquatic breeding amphibians (Anura) in a seasonally dry tropical forest in Chamela, Mexico

Luna-Gómez

García

Santos-Barrera

2017

RBT

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Abstract:The distribution of amphibians is affected by abiotic and biotic factors, availability of resources and the characteristics of reproductive sites. In particular, reproductive activity of aquatic-breeding anurans that inhabit tropical dry areas is affected by rainfall, which determines the availability and quality of reproductive sites. In this study, we analyzed the spatial and temporal distribution of anurans with indirect development in a tropical dry forest in Western Mexico, during two rainy seasons (July 10-October 4, 2013, and June 26-September 26, 2014). We collected data on the occupancy and reproductive activity of 15 species in four temporary streams, and evaluated their relationship with precipitation, humidity and temperature. We determined richness, abundance and diversity of species in each stream; we also identified differences in the reproductive strategies and microhabitats used by the species. The most abundant species were: Tlalocohyla smithii and Exerodonta smaragdina, whereas the least abundant were Leptodactylus melanonotus and Incilius mazatlanensis. Species richness, abundance and reproductive activity peaked alongside the stream with the greatest number of breeding sites (e.g. pools). We found temporal segregation in the occupancy and reproductive activity of species in all streams which were mainly associated with precipitation. However, occupancy and reproductive activity of some species overlapped up to four weeks during part of the breeding season. Most species used specific substrates for particular reproductive activities (e.g. oviposition), but used a range of microhabitats (leaf-litter, water, rocks, branches, leaves, logs, etc.) for others (e.g. calling). We discuss these behavioral differences as factors that facilitate coexistence of species in this environment in the rainy season. Rev. Biol. Trop. 65 (3): 1082-1094. Epub 2017 September 01.Key words: amphibians, reproductive strategies, environmental seasonality, reproductive activity, indirect development.Reproductive activity of anuran species is strongly influenced by abiotic factors such as precipitation and temperature (Moreira & Lima, 1991;Bertoluci, 1998;Ford & Scott, 2006;Saenz, Fitzgerald, Baum, & Conner 2006;Schalk & Saenz, 2016). It is further suggested that community structure is associated with reproductive phenology, as the sequence and variations of these events largely determine species composition at the local scale (Sáenz et al., 2006;Afonso & Eterovick, 2007). Anuran species that coexist present important differences in morphology, physiology, and behavior (Crump, 1974;Pough, Stewart, & Thomas, 1977;Cardoso, Andrade, & Haddad, 1989;Afonso & Eterovick, 2007). During the reproductive season, resource overlapping within the community becomes more intense (Bertoluci & Rodrigues, 2002), therefore species can exhibit temporal or spatial segregation or partial/complete overlap in the use of resources (Rossa-Feres & Jim, 2001). Temporal partitioning can be directly related to each region´s climate, partic...

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Spatial distribution and habitat preferences of co-occurring vertebrate species: Case study of an endangered frog and an introduced toad in Fiji.

Cited by 10 publications

References 0 publications

Sight of a Predator Induces a Corticosterone Stress Response and Generates Fear in an Amphibian

Sight of a Predator Induces a Corticosterone Stress Response and Generates Fear in an Amphibian

Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic

Spatial and temporal distribution and microhabitat use of aquatic breeding amphibians (Anura) in a seasonally dry tropical forest in Chamela, Mexico

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