Quantifying similarity in animal vocal sequences: Which metric performs best?

1. Many animals communicate using sequences of discrete acoustic elements which can be complex, vary in their degree of stereotypy, and are potentially open-ended. Variation in sequences can provide important ecological, behavioural, or evolutionary information about the structure and connectivity of populations, mechanisms for vocal cultural evolution, and the underlying drivers responsible for these processes. Various mathematical techniques have been used to form a realistic approximation of sequence similarity for such tasks. 2. Here, we use both simulated and empirical datasets from animal vocal sequences (rock hyrax, Procavia capensis; humpback whale, Megaptera novaeangliae; bottlenose dolphin, Tursiops truncatus; and Carolina chickadee, Poecile carolinensis) to test which of eight sequence analysis metrics are more likely to reconstruct the information encoded in the sequences, and to test the fidelity of estimation of model parameters, when the sequences are assumed to conform to particular statistical models. 3. Results from the simulated data indicated that multiple metrics were equally successful in reconstructing the information encoded in the sequences of simulated individuals (Markov chains, n-gram models, repeat distribution, and edit distance), and data generated by different stochastic processes (entropy rate and n-grams). However, the string edit (Levenshtein) distance performed consistently and significantly better than all other tested metrics (including entropy, Markov chains, n-grams, mutual information) for all empirical datasets, despite being less commonly used in the field of animal acoustic communication. 4. The Levenshtein distance metric provides a robust analytical approach that should be considered in the comparison of animal acoustic sequences in preference to other commonly employed techniques (such as Markov chains, hidden Markov models, or Shannon entropy). The recent discovery that non-Markovian vocal sequences may be more common in animal communication than previously thought, provides a rich area for future research that requires non-Markovian based analysis techniques to investigate animal grammars and potentially the origin of human language.We thank Melinda Rekdahl, Todd Freeberg and his graduate students, Amiyaal Ilany, Elizabeth Hobson, and Jessica Crance for providing comments of on a previous version of this manuscript. We thank Mike Noad, Melinda Rekdahl, and Claire Garrigue for assistance with humpback whale song collection and initial categorisation of the song, Vincent Janik and Laela Sayigh for assistance with signature whistle collection, Todd Freeberg with chickadee recordings, and Eli Geffen and Amiyaal Ilany for assistance with hyrax song collection and analysis. E.C.G is supported by a Newton International Fellowship. Part of this work was conducted while E.C.G. was supported by a National Research Council (National Academy of Sciences) Postdoctoral Fellowship at the National Marine Mammal Laboratory, AFSC, NMFS, NOAA. The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Marine Fisheries Service. We would also like to thank Randall Wells and the Sarasota Dolphin Research Program for the opportunity to record the Sarasota dolphins, where data were collected under a series of National Marine Fisheries Service Scientific Research Permits issued to Randall Wells. A.K. is supported by the Herchel Smith Postdoctoral Fellowship Fund. Part of this work was conducted while A.K. was a Postdoctoral Fellow at the National Institute for Mathematical and Biological Synthesis, an Institute sponsored by the National Science Foundation through NSF Award #DBI-1300426, with additional support from The University of Tennessee, Knoxville.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/2041-210X.1243

Identifying gaps in climate litigation-relevant research: an assessment from interviews with legal scholars and practitioners

Climate litigation-relevant research has enjoyed high impact in recent years in the legal, media, and academic arenas. Yet there remains ample room for growth in terms of both the number of active researchers in the field and the range of topics analyzed. Through interviews with legal scholars and practitioners, this research identifies a variety of climate litigation-relevant research topics to inform research agendas, identify potential priority areas, and illuminate new topics

Information theory analysis of Australian humpback whale song

Songs produced by migrating whales were recorded off the coast of Queensland, Australia, over six consecutive weeks in 2003. Forty-eight independent song sessions were analyzed using information theory techniques. The average length of the songs estimated by correlation analysis was approximately 100 units, with song sessions lasting from 300 to over 3100 units. Song entropy, a measure of structural constraints, was estimated using three different methodologies: (1) the independently identically distributed model, (2) a first-order Markov model, and (3) the nonparametric sliding window match length (SWML) method, as described by Suzuki et al. [(2006). “Information entropy of humpback whale song,” J. Acoust. Soc. Am. 119, 1849–1866]. The analysis finds that the song sequences of migrating Australian whales are consistent with the hierarchical structure proposed by Payne and McVay [(1971). “Songs of humpback whales,” Science 173, 587–597], and recently supported mathematically by Suzuki et al. (2006) for singers on the Hawaiian breeding grounds. Both the SWML entropy estimates and the song lengths for the Australian singers in 2003 were lower than that reported by Suzuki et al. (2006) for Hawaiian whales in 1976–1978; however, song redundancy did not differ between these two populations separated spatially and temporally. The average total information in the sequence of units in Australian song was approximately 35 bits/song. Aberrant songs (8%) yielded entropies similar to the typical songs

Research Priorities for Climate Litigation

This article characterizes key research gaps and opportunities for scientists across disciplines to do work that informs the rapidly growing number of climate lawsuits worldwide. It focuses on research that can be used to inform legal decisions about responsibility for greenhouse gas emissions and climate damages. Relevant lawsuits include claims filed against government and corporate defendants alleging that they have violated environmental, human rights, constitutional, tort, and consumer protection laws due to their contributions to climate change and failures to control emissions. Constructive attention has recently been given to the important role of attribution science in informing some of these cases (Burger et al., 2020, https://doi.org/10.7916/cjel.v45i1.4730; Stuart-Smith et al., 2021, https://doi.org/10.1038/s41561-021-00686-4). Here, we draw upon both the published literature and conversations with diverse legal scholars and practitioners to characterize what further climate litigation-relevant research is most needed. In addition to key gaps in litigation-relevant attribution science, we identify and characterize the need and opportunity for further social science research to address the causes of climate inaction, and for further cross-disciplinary research to inform emerging legal questions on the allocation of responsibility for emissions reductions to align with temperature limits such as those set by the Paris Climate Agreement. Our primary goal is to identify areas for researchers who are interested in contributing to climate litigation and discussions about legal responsibility for climate change. We also seek to help the research community see this as a legitimate and important domain for timely, actionable scientific research

Research priorities for climate litigation

This article characterizes key research gaps and opportunities for scientists across disciplines to do work that informs the rapidly growing number of climate lawsuits worldwide. It focuses on research that can be used to inform legal decisions about responsibility for greenhouse gas emissions and climate damages. Relevant lawsuits include claims filed against government and corporate defendants alleging that they have violated environmental, human rights, constitutional, tort, and consumer protection laws due to their contributions to climate change and failures to control emissions. Constructive attention has recently been given to the important role of attribution science in informing some of these cases (Burger et al., 2020, https://doi.org/10.7916/cjel.v45i1.4730; Stuart-Smith et al., 2021, https://doi.org/10.1038/s41561-021-00686-4). Here, we draw upon both the published literature and conversations with diverse legal scholars and practitioners to characterize what further climate litigation-relevant research is most needed. In addition to key gaps in litigation-relevant attribution science, we identify and characterize the need and opportunity for further social science research to address the causes of climate inaction, and for further cross-disciplinary research to inform emerging legal questions on the allocation of responsibility for emissions reductions to align with temperature limits such as those set by the Paris Climate Agreement. Our primary goal is to identify areas for researchers who are interested in contributing to climate litigation and discussions about legal responsibility for climate change. We also seek to help the research community see this as a legitimate and important domain for timely, actionable scientific research

Emissions pathways, climate change, and impacts on California

The magnitude of future climate change depends substantially on the greenhouse gas emission pathways we choose. Here we explore the implications of the highest and lowest Intergovernmental Panel on Climate Change emissions pathways for climate change and associated impacts in California. Based on climate projections from two state-of-the-art climate models with low and medium sensitivity (Parallel Climate Model and Hadley Centre Climate Model, version 3, respectively), we find that annual temperature increases nearly double from the lower B1 to the higher A1fi emissions scenario before 2100. Three of four simulations also show greater increases in summer temperatures as compared with winter. Extreme heat and the associated impacts on a range of temperature-sensitive sectors are substantially greater under the higher emissions scenario, with some interscenario differences apparent before midcentury. By the end of the century under the B1 scenario, heatwaves and extreme heat in Los Angeles quadruple in frequency while heat-related mortality increases two to three times; alpine subalpine forests are reduced by 50–75%; and Sierra snowpack is reduced 30–70%. Under A1fi, heatwaves in Los Angeles are six to eight times more frequent, with heat-related excess mortality increasing five to seven times; alpine subalpine forests are reduced by 75–90%; and snowpack declines 73–90%, with cascading impacts on runoff and streamflow that, combined with projected modest declines in winter precipitation, could fundamentally disrupt California’s water rights system. Although interscenario differences in climate impacts and costs of adaptation emerge mainly in the second half of the century, they are strongly dependent on emissions from preceding decades

The evolutionary roots of creativity: mechanisms and motivations

Funding: MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.We consider the evolution of cognition and the emergence of creative behaviour, in relation to vocal communication. We address two key questions: (i) what cognitive and/or social mechanisms have evolved that afford aspects of creativity?; (ii) has natural and/or sexual selection favoured human behaviours considered ‘creative’? This entails analysis of ‘creativity’, an imprecise construct: comparable properties in non-humans differ in magnitude and teleology from generally agreed human creativity. We then address two apparent problems: (i) the difference between merely novel productions and ‘creative’ ones; (ii) the emergence of creative behaviour in spite of high cost: does it fit the idea that females choose a male who succeeds in spite of a handicap (costly ornament); or that creative males capable of producing a large and complex song repertoire grew up under favourable conditions; or a demonstration of generally beneficial heightened reasoning capacity; or an opportunity to continually reinforce social bonding through changing communication tropes; or something else? We illustrate and support our argument by reference to whale and bird song; these independently evolved biological signal mechanisms objectively share surface properties with human behaviours generally called ‘creative’. Studying them may elucidate mechanisms underlying human creativity; we outline a research programme to do so.PostprintPeer reviewe

Increasing Public Understanding of Climate Risks & Choices: Learning from Social Science Research and Practice

This report summarizes a 2012 conference on the topic of generating greater public understanding of the issue of climate change.The Erb Institute for Global Sustainable EnterpriseThe Union of Concerned Scientistshttps://deepblue.lib.umich.edu/bitstream/2027.42/138021/1/UCS_Erb Workshop Report.pdf8Description of UCS_Erb Workshop Report.pdf : Final Repor

One step forward, two steps back?:the fading contours of (in)justice in competing discourses on climate migration

In recent debates on climate change and migration, the focus on the figure of ‘climate refugees’ (tainted by environmental determinism and a crude understanding of human mobility) has given ground to a broader conception of the climate–migration nexus. In particular, the idea that migration can represent a legitimate adaptation strategy has emerged strongly. This appears to be a positive development, marked by softer tones that de-securitise climate migration. However, political and normative implications of this evolution are still understudied. This article contributes to filling the gap by turning to both the ‘climate refugees’ and ‘migration as adaptation’ narratives, interrogating how and whether those competing narratives pose the question of (in)justice. Our analysis shows that the highly problematic ‘climate refugees’ narrative did (at least) channel justice claims and yielded the (illusory) possibility of identifying concrete rights claims and responsibilities. Read in relation to the growing mantra of resilience in climate policy and politics, the more recent narrative on ‘migration as adaptation’ appears to displace justice claims and inherent rights in favour of a depoliticised idea of adaptation that relies on the individual migrant's ability to compete in and benefit from labour markets. We warn that the removal of structural inequalities from the way in which the climate–migration nexus is understood can be seen as symptomatic of a shrinking of the conditions to posing the question of climate justice

Attributing ocean acidification to major carbon producers

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Licker, R.; Ekwurzel, B.; Doney, S. C.; Cooley, S. R.; Lima, I. D.; Heede, R.; Frumhoff, P. C. Attributing ocean acidification to major carbon producers. Environmental Research Letters. 14(12), (2019): 124060, doi:10.1088/1748-9326/ab5abc.Recent research has quantified the contributions of CO2 and CH4 emissions traced to the products of major fossil fuel companies and cement manufacturers to global atmospheric CO2, surface temperature, and sea level rise. This work has informed societal considerations of the climate responsibilities of these major industrial carbon producers. Here, we extend this work to historical (1880–2015) and recent (1965–2015) acidification of the world's ocean. Using an energy balance carbon-cycle model, we find that emissions traced to the 88 largest industrial carbon producers from 1880–2015 and 1965–2015 have contributed ~55% and ~51%, respectively, of the historical 1880–2015 decline in surface ocean pH. As ocean acidification is not spatially uniform, we employ a three-dimensional ocean model and identify five marine regions with large declines in surface water pH and aragonite saturation state over similar historical (average 1850–1859 to average 2000–2009) and recent (average 1960–1969 to average of 2000–2009) time periods. We characterize the biological and socioeconomic systems in these regions facing loss and damage from ocean acidification in the context of climate change and other stressors. Such analysis can inform societal consideration of carbon producer responsibility for current and near-term risks of further loss and damage to human communities dependent on marine ecosystems and fisheries vulnerable to ocean acidification.The approach of using equation (1) benefited from discussions with Myles R Allen (University of Oxford) and Inez Fung (University of California, Berkeley). M W Dalton provided insights for the incorporation of the updated carbon producers data. Chloe Ames provided support for references. S Doney acknowledges support from the US National Science Foundation and the University of Virginia Environmental Resilience Institute. R Licker, B Ekwurzel and P C Frumhoff acknowledge the support of the Grantham Foundation for the Protection of the Environment, Wallace Global Fund, and Rockefeller Family Fund to the Union of Concerned Scientists. R Heede gratefully acknowledges the financial support of Wallace Global Fund, Rockefeller Brothers Fund, and Union of Concerned Scientists. We thank two anonymous reviewers for their helpful comments, which greatly improved our manuscript