Red Hot Frogs

Red hot frogs: identifying the Australian frogs most at Risk of Extinction written by Heather M. Geyle, Conrad J. Hoskin, David S. Bower, Rebecca Catullo, Scott Clulow, Matthew Driessen, John C. Z. Woinarski, Graeme R. Gillespie.

This article aims to identify the most at-risk Australian frog species that are predicted to be extinct by 2040 with over 18% of the Australian frog species classified as threatened according to the IUCN criteria. These frogs are at risk and it's due to climate change. Many of the frog species are endemic to Queensland with small geographic ranges that are vulnerable to stochastic events. This article aims to highlight the urgent need to increase resourcing and management intervention to prevent the extinction of these species with the suggestions of developing and supporting captive management and establishing or extending the population refuges to alleviate the impacts of diseases and climate change. They hypothesize that, by using structured expert elicitation, they can identify the Australian frog species that are most at risk of extinction and evaluate the primary threats that are driving their extinction. 

Material and Method:

During this research, they assessed 26 different Australian frog species which 22 of the species are listed as Critically Endangered (CR), and two of the CR are considered to be possibly extinct. They used a structured expert elicitation method

  to estimate the probability of extinction between the 26 Australian frog species based on the Delphi and investigation, discuss, estimate and aggregate (IDEA) approaches which aim to reduce cognitive and motivational biases in expert elicitation processes. This procedure involves four main steps which were conducted via email/phone:

1. Participants were given a summary of all information they needed from ecology. threats etc and then asked to estimate the probability of extinction by 2040. All estimates were complied and modeled using a linear mixed effect model that allowed the researchers to predict the probability of extinction for each species with a 95% confidence interval. The statistics were calculated and participants were provided with figures displaying the summary statistics and their estimates. 
2. The estimate of extinction probability for each species was collected and to analyzed using a linear mixed-effect model that accounted for variations in estimates among the participants. The model allowed the researchers to predict the probability for each species with a 95% confidence interval and calculate summary statistics (mean, median, range, and outliers) 
3. After collecting the individual estimates of extinction probability and modeling them using a mixed effects model, after reviewing the results provided a teleconference was held to discuss discrepancies and concerns allowing participants to clarify information, introduce relevant information, and cross-examine new information. These conversations were recorded and detailed minutes were provided for all participants even for those who weren't able to attend. 
4. After, all participants were asked to provide a final assessment of the probability of extinction for each species along with their level of confidence. This was also considered "round two" and the scores were used to finalize the results. 

Results:

The result showed that on average, the experts adjusted their scores for 58% of the species they assessed in the second round, resulting in changes to the modeled probabilities for every species under consideration. The predicted probabilities for most species (69%) are under consideration and on average there was an 8% decrease in the modeled probability of extinction. However, the predicted probability of extinction for eight species (31%) increased by 3.9%.

The final scores for that 8 of the 26 species are at high risk of becoming extinct within the next 20 years. And 5 species were scored at moderate-high risk by 30-50% within the next 20 years. 

Table 1 shows the likelihood of extinction that was determined which was through the structure expert elicitation with lower and upper 95% confidence intervals. These species were ranked based on their probability of extinction from highest to lowest. These categories used were EX for extinct, CR for Critically Endangered, EN for endangered, VU for vulnerable, and NA for Not Assessed.

There was a high level of agreement among the participants in the relative ranking of species in their assessments of extinction risk and the summed possibilities across the remaining extinction risk values assigned by participants averaged out to 6.7 additional species that could be lost by 2040 without changes to resourcing, monitoring, and management. 

Figure two shows the differences between the average scores given by experts and non-experts in both rounds (dark gray=Round 1 and light gray=Round 2). A positive score means that the experts gave higher scores than the non-experts while a negative scores mean that the non-experts gave a higher score than the experts. However, a score of 0 means that there were no differences between the two groups. 

When analyzing the figure, the average expert confidence in prediction probabilities was higher than the non-expert confidence in both rounds of the structured expert elicitation. The average expert probabilities decreased in round 2 compared to round 1. 

Figure 3. A summary of management and research activities for the 26 species of Australian frog species that was taken from Gillespie et al, and a higher implementation score indicates a higher priority based on the extinction probability, conservative value, feasibility, and also the current levels of implementation and resourcing. This graph includes a box plot graph to show the median, first and third quartiles, average, minimum, and maximum values of the implementation scores for each action as well as the total number of species for which each action was assigned. 

Discussion:

Again, this study was to study the extinction risk of Australian frog species that used expert elicitation where experts were asked to estimate the probability of extinction of the 26 species. They found that 4 species were already considered extinct and 4 others to be well on their way to extinction within the next 20 years and 5 additional species that are considered moderately at high risk of extinction within the next two decades if no improvements are made to help prevent such thing from happening. 

The study suggested that conservation management gains can be made by developing and supporting captive management as well as establishing and or extending in-situ population regulation to alleviate the detrimental impacts of emergent diseases. 

scientist felt like providing the public with knowledge of the species distribution, ecological requirements, conservation status, etc was the most frequently high-ranking research action. Climate change and Batrachochytrium dendrobatidis (B. dendrobatidis), a fungal disease were considered some of the major threats to the frog species. 

The study aims to highlight that the need for urgent action is needed to address the extinction risk faced by Australian frog species given the diminishing population sizes of many of the species and the increases in intensity of the threats. 

Work Cited:

Geyle, H. M., Hoskin, C. J., Bower, D. S., Catullo, R., Clulow, S., Driessen, M., ... & Gillespie, G. R. (2021). Red hot frogs: identifying the Australian frogs most at risk of extinction. Pacific Conservation Biology, 28(3), 211-223.