Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic Narayan, Edward J, Jessop, Tim S and Hero, Jean- Marc 2015, Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic, Functional ecology, vol. 29, no. 11, pp. 1435-1444, doi: 10.1111/1365-2435.12446. Attached Files Name Description MIMEType Size Downloads Title Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic Author(s) Narayan, Edward J Jessop, Tim S Hero, Jean- Marc Journal name Functional ecology Volume number 29 Issue number 11 Start page 1435 End page 1444 Total pages 10 Publisher Wiley Place of publication London, Eng. Publication date 2015-11 ISSN 0269-8463 1365-2435 Keyword(s) chronic stress Fiji fitness loss global extinction crisis island invasion nutritional stress reproduction Rhinella marina survival Summary 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. 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 × 10 000 m2), 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. 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. 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. Language eng DOI 10.1111/1365-2435.12446 Field of Research 060603 Animal Physiology - Systems 060803 Animal Developmental and Reproductive Biology 050103 Invasive Species Ecology 06 Biological Sciences 05 Environmental Sciences Socio Economic Objective 970106 Expanding Knowledge in the Biological Sciences HERDC Research category C1 Refereed article in a scholarly journal ERA Research output type C Journal article Copyright notice ©2015, Wiley Persistent URL http://hdl.handle.net/10536/DRO/DU:30075660 Document type: Journal Article Collections: School of Life and Environmental Sciences Centre for Integrative Ecology Related Links Link Description Connect to published version Go to link with your DU access privileges   Connect to Elements publication management system Go to link with your DU access privileges     Unless expressly stated otherwise, the copyright for items in DRO is owned by the author, with all rights reserved. Versions Version Filter Type Tue, 18 Aug 2015, 14:42:02 EST Wed, 19 Aug 2015, 05:02:08 EST Thu, 20 Aug 2015, 08:38:08 EST Thu, 07 Jan 2016, 09:42:29 EST Fri, 08 Jan 2016, 05:07:06 EST Fri, 24 Jun 2016, 15:33:37 EST Tue, 12 Jul 2016, 11:48:18 EST Wed, 12 Oct 2016, 13:55:16 EST Wed, 01 Mar 2017, 07:14:46 EST Filtered Full Citation counts:   Cited 4 times in TR Web of Science Cited 5 times in Scopus Search Google Scholar Access Statistics: 77 Abstract Views, 2 File Downloads  -  Detailed Statistics Created: Thu, 07 Jan 2016, 09:42:29 EST

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