A small dasyurid predator (Sminthopsis virginiae) rapidly learns to avoid a toxic invader

2011 ◽  
Vol 38 (8) ◽  
pp. 726 ◽  
Author(s):  
Jonathan K. Webb ◽  
David Pearson ◽  
Richard Shine
Keyword(s):  
Western Australia ◽  
Small Sample ◽  
Ecological Impacts ◽  
Population Declines ◽  
Cane Toad ◽  
Taste Aversion Learning ◽  
The North ◽  
Formidable Challenge ◽  
Mammalian Predators ◽  
Small Sample Sizes

Context Invasive species are a leading cause of extinctions, yet predicting their ecological impacts poses a formidable challenge for conservation biologists. When native predators are naïve to invaders, they may lack appropriate behaviours to deal with the invader. In northern Australia, the invasion of the highly toxic cane toad (Rhinella marina) has caused serious population declines of reptilian and mammalian predators that are ill equipped to deal with toad toxins. Cane toads recently invaded the Kimberley region of Western Australia, where they potentially threaten several species of small dasyurid predators. Aims We investigated whether red-cheeked dunnarts (Sminthopsis virginiae) attack cane toads, and if so, whether individuals subsequently learn to avoid toads as prey. Methods We quantified feeding and learning behaviours in toad-naïve red-cheeked dunnarts from the north Kimberley in Western Australia. Key results All toad-naïve dunnarts attacked toads during their first encounter. Most dunnarts bit the toad on the snout, killed it by biting the cranium, and consumed the toad snout-first, thereby initially avoiding the toad’s parotoid glands. Most dunnarts partially consumed toads before discarding them, and only one animal showed visible signs of toad poisoning. All dunnarts rapidly learnt to avoid toads as prey after one or two encounters. Predators rejected toads as prey for the duration of the study (22 days), suggesting long-term retention of the knowledge that toads are noxious. Conclusions Our results show that red-cheeked dunnarts rapidly learn to avoid cane toads as prey. Implications Our study was limited by small sample sizes, but our results suggest that small dasyurids can adapt to the cane toad invasion via taste aversion learning.

Predation on toxic cane toads (Bufo marinus) may imperil bluetongue lizards (Tiliqua scincoides intermedia, Scincidae) in tropical Australia

2010 ◽  
Vol 37 (2) ◽  
pp. 166 ◽  
Author(s):  
Samantha J. Price-Rees ◽  
Gregory P. Brown ◽  
Richard Shine
Keyword(s):  
Population Decline ◽  
Bufo Marinus ◽  
Ecological Impacts ◽  
Laboratory Research ◽  
Direct Result ◽  
Population Declines ◽  
Cane Toad ◽  
Lizard Species ◽  
Stochastic Variation ◽  
Tropical Australia

Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion; however, one lineage (the bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.

scholarly journals Unexpectedly high genetic diversity in a rare and endangered seabird in the Hawaiian Archipelago

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8463 ◽  
Author(s):  
Carmen C. Antaky ◽  
Emily E. Conklin ◽  
Robert J. Toonen ◽  
Ingrid S.S. Knapp ◽  
Melissa R. Price
Keyword(s):  
Genetic Diversity ◽  
High Throughput Sequencing ◽  
Breeding Population ◽  
Small Sample ◽  
Population Declines ◽  
High Genetic Diversity ◽  
Low Genetic Diversity ◽  
Avian Order ◽  
Rare And Endangered ◽  
Small Sample Sizes

Seabirds in the order of Procellariiformes have one of the highest proportions of threatened species of any avian order. Species undergoing recovery may be predicted to have a genetic signature of a bottleneck, low genetic diversity, or higher rates of inbreeding. The Hawaiian Band-rumped Storm Petrel (‘Akē‘akē; Hydrobates castro), a long-lived philopatric seabird, suffered massive population declines resulting in its listing under the Endangered Species Act in 2016 as federally Endangered. We used high-throughput sequencing to assess patterns of genetic diversity and potential for inbreeding in remaining populations in the Hawaiian Islands. We compared a total of 24 individuals, including both historical and modern samples, collected from breeding colonies or downed individuals found on the islands of Kaua‘i, O‘ahu, Maui, and the Big Island of Hawai‘i. Genetic analyses revealed little differentiation between breeding colonies on Kaua‘i and the Big Island colonies. Although small sample sizes limit inferences regarding other island colonies, downed individuals from O‘ahu and Maui did not assign to known breeding colonies, suggesting the existence of an additional distinct breeding population. The maintenance of genetic diversity in future generations is an important consideration for conservation management. This study provides a baseline of population structure for the remaining nesting colonies that could inform potential translocations of the Endangered H. castro.

scholarly journals Ultra-Microscale (5–25 μg C) Analysis of Individual Lipids by 14C AMS: Assessment and Correction for Sample Processing Blanks

Radiocarbon ◽  
2007 ◽  
Vol 49 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Sunita R Shah ◽  
Ann Pearson
Keyword(s):  
Water Column ◽  
Euphotic Zone ◽  
Total Sample ◽  
Small Sample ◽  
Sample Processing ◽  
Central Pacific ◽  
The North ◽  
Pure Compounds ◽  
Small Sample Sizes ◽  
Different Sources

Measurements of the natural abundance of radiocarbon in biomarker molecules can be used to elucidate the biogeochemical roles of marine bacteria and archaea in the oceanic water column. However, the relatively low concentration of biomass, especially below the euphotic zone, inevitably results in small sample sizes for compound-specific analyses. In ultra-microscale Δ14C measurements, which we define as measurements on samples smaller than 25 μg C, the process of isolating pure compounds and preparing them for measurement adds significant background carbon. This additional blank carbon can contribute up to 40% of the total sample mass; therefore, it is necessary to quantify all components of the processing blank in order to make appropriate corrections. Complete propagation of error is critical in order to report the correct analytical uncertainty. The carbon blank is composed of at least 3 different sources: i) those that scale in proportion to the mass of the sample; ii) sources that contribute a constant mass of blank, e.g. closed-tube combustion; and iii) contaminants from vacuum lines and/or other aspects of sample handling that are difficult to quantify. We approached the problem of correcting for the total sample processing blank by deriving a 4-part isotopic mass balance based on separating the 3 exogenous components from the sample. Subsequently, we derived the appropriate equations for the full propagation of error associated with these corrections. Equations for these terms are presented. Full treatment of a set of raw data is demonstrated using compound-specific Δ14C data from the North Central Pacific water column.

A detrital zircon test of large-scale terrane displacement along the Arctic margin of North America

Geology ◽  
2021 ◽  
Author(s):  
Timothy M. Gibson ◽  
Karol Faehnrich ◽  
James F. Busch ◽  
William C. McClelland ◽  
Mark D. Schmitz ◽  
...  
Keyword(s):  
North America ◽  
Detrital Zircon ◽  
Large Scale ◽  
Small Sample ◽  
The Arctic ◽  
North Slope ◽  
The North ◽  
Arctic Alaska ◽  
Laurentian Margin ◽  
Small Sample Sizes

Detrital zircon U-Pb geochronology is one of the most common methods used to constrain the provenance of ancient sedimentary systems. Yet, its efficacy for precisely constraining paleogeographic reconstructions is often complicated by geological, analytical, and statistical uncertainties. To test the utility of this technique for reconstructing complex, margin-parallel terrane displacements, we compiled new and previously published U-Pb detrital zircon data (n = 7924; 70 samples) from Neoproterozoic–Cambrian marine sandstone-bearing units across the Porcupine shear zone of northern Yukon and Alaska, which separates the North Slope subterrane of Arctic Alaska from northwestern Laurentia (Yukon block). Contrasting tectonic models for the North Slope subterrane indicate it originated either near its current position as an autochthonous continuation of the Yukon block or from a position adjacent to the northeastern Laurentian margin prior to >1000 km of Paleozoic–Mesozoic translation. Our statistical results demonstrate that zircon U-Pb age distributions from the North Slope subterrane are consistently distinct from the Yukon block, thereby supporting a model of continent-scale strike-slip displacement along the Arctic margin of North America. Further examination of this dataset highlights important pitfalls associated with common methodological approaches using small sample sizes and reveals challenges in relying solely on detrital zircon age spectra for testing models of terranes displaced along the same continental margin from which they originated. Nevertheless, large-n detrital zircon datasets interpreted within a robust geologic framework can be effective for evaluating translation across complex tectonic boundaries.

Integrating Visual and Bayesian Statistical Analyses in Single Case Experimental Research to Evaluate the Effectiveness and Magnitude of a Comprehensive Behavioral Intervention

2018 ◽  
Author(s):  
Prathiba Natesan ◽  
Smita Mehta
Keyword(s):  
Behavioral Intervention ◽  
Effect Size ◽  
Rate Ratio ◽  
Visual Analysis ◽  
Single Case ◽  
Small Sample ◽  
Statistical Analyses ◽  
Data Types ◽  
Ratio Effect ◽  
Small Sample Sizes

Single case experimental designs (SCEDs) have become an indispensable methodology where randomized control trials may be impossible or even inappropriate. However, the nature of SCED data presents challenges for both visual and statistical analyses. Small sample sizes, autocorrelations, data types, and design types render many parametric statistical analyses and maximum likelihood approaches ineffective. The presence of autocorrelation decreases interrater reliability in visual analysis. The purpose of the present study is to demonstrate a newly developed model called the Bayesian unknown change-point (BUCP) model which overcomes all the above-mentioned data analytic challenges. This is the first study to formulate and demonstrate rate ratio effect size for autocorrelated data, which has remained an open question in SCED research until now. This expository study also compares and contrasts the results from BUCP model with visual analysis, and rate ratio effect size with nonoverlap of all pairs (NAP) effect size. Data from a comprehensive behavioral intervention are used for the demonstration.

No Evidence that Experiencing Physical Warmth Promotes Interpersonal Warmth: Two Failures to Replicate Williams and Bargh (2008)

2018 ◽  
Author(s):  
Christopher Chabris ◽  
Patrick Ryan Heck ◽  
Jaclyn Mandart ◽  
Daniel Jacob Benjamin ◽  
Daniel J. Simons
Keyword(s):  
Null Hypothesis ◽  
Small Sample ◽  
Sample Sizes ◽  
Double Blind ◽  
Bayesian Analyses ◽  
Physical Warmth ◽  
Small Sample Sizes ◽  
Interpersonal Warmth

Williams and Bargh (2008) reported that holding a hot cup of coffee caused participants to judge a person’s personality as warmer, and that holding a therapeutic heat pad caused participants to choose rewards for other people rather than for themselves. These experiments featured large effects (r = .28 and .31), small sample sizes (41 and 53 participants), and barely statistically significant results. We attempted to replicate both experiments in field settings with more than triple the sample sizes (128 and 177) and double-blind procedures, but found near-zero effects (r = –.03 and .02). In both cases, Bayesian analyses suggest there is substantially more evidence for the null hypothesis of no effect than for the original physical warmth priming hypothesis.

scholarly journals Non-Invasive Monitoring of Adrenocortical Activity in Three Sympatric Desert Gerbil Species

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 75
Author(s):  
Álvaro Navarro-Castilla ◽  
Mario Garrido ◽  
Hadas Hawlena ◽  
Isabel Barja
Keyword(s):  
Small Sample ◽  
Post Injection ◽  
Control Groups ◽  
Treatment Groups ◽  
Adrenocortical Activity ◽  
Non Invasive ◽  
Endocrine Status ◽  
Corticosterone Metabolites ◽  
Small Sample Sizes ◽  
Fecal Corticosterone Metabolites

The study of the endocrine status can be useful to understand wildlife responses to the changing environment. Here, we validated an enzyme immunoassay (EIA) to non-invasively monitor adrenocortical activity by measuring fecal corticosterone metabolites (FCM) in three sympatric gerbil species (Gerbillus andersoni, G. gerbillus and G. pyramidum) from the Northwestern Negev Desert’s sands (Israel). Animals included into treatment groups were injected with adrenocorticotropic hormone (ACTH) to stimulate adrenocortical activity, while control groups received a saline solution. Feces were collected at different intervals and FCM were quantified by an EIA. Basal FCM levels were similar in the three species. The ACTH effect was evidenced, but the time of FCM peak concentrations appearance differed between the species (6–24 h post-injection). Furthermore, FCM peak values were observed sooner in G. andersoni females than in males (6 h and 18 h post-injection, respectively). G. andersoni and G. gerbillus males in control groups also increased FCM levels (18 h and 48 h post-injection, respectively). Despite the small sample sizes, our results confirmed the EIA suitability for analyzing FCM in these species as a reliable indicator of the adrenocortical activity. This study also revealed that close species, and individuals within a species, can respond differently to the same stressor.

scholarly journals Use of Antiplatelet Agents Decreases the Positive Predictive Value of Fecal Immunochemical Tests for Colorectal Cancer but Does Not Affect Their Sensitivity

2021 ◽  
Vol 11 (6) ◽  
pp. 497
Author(s):  
Yoonsuk Jung ◽  
Eui Im ◽  
Jinhee Lee ◽  
Hyeah Lee ◽  
Changmo Moon
Keyword(s):  
Colorectal Cancer ◽  
Large Scale ◽  
Screening Program ◽  
Antiplatelet Agents ◽  
Population Based ◽  
Small Sample ◽  
Antithrombotic Agents ◽  
Predictive Values ◽  
Prescription Rates ◽  
Small Sample Sizes

Previous studies have evaluated the effects of antithrombotic agents on the performance of fecal immunochemical tests (FITs) for the detection of colorectal cancer (CRC), but the results were inconsistent and based on small sample sizes. We studied this topic using a large-scale population-based database. Using the Korean National Cancer Screening Program Database, we compared the performance of FITs for CRC detection between users and non-users of antiplatelet agents and warfarin. Non-users were matched according to age and sex. Among 5,426,469 eligible participants, 768,733 used antiplatelet agents (mono/dual/triple therapy, n = 701,683/63,211/3839), and 19,569 used warfarin, while 4,638,167 were non-users. Among antiplatelet agents, aspirin, clopidogrel, and cilostazol ranked first, second, and third, respectively, in terms of prescription rates. Users of antiplatelet agents (3.62% vs. 4.45%; relative risk (RR): 0.83; 95% confidence interval (CI): 0.78–0.88), aspirin (3.66% vs. 4.13%; RR: 0.90; 95% CI: 0.83–0.97), and clopidogrel (3.48% vs. 4.88%; RR: 0.72; 95% CI: 0.61–0.86) had lower positive predictive values (PPVs) for CRC detection than non-users. However, there were no significant differences in PPV between cilostazol vs. non-users and warfarin users vs. non-users. For PPV, the RR (users vs. non-users) for antiplatelet monotherapy was 0.86, while the RRs for dual and triple antiplatelet therapies (excluding cilostazol) were 0.67 and 0.22, respectively. For all antithrombotic agents, the sensitivity for CRC detection was not different between users and non-users. Use of antiplatelet agents, except cilostazol, may increase the false positives without improving the sensitivity of FITs for CRC detection.

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