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Odom KJ, Araya-Salas M, Morano JL, Ligon RA, Leighton GM, Taff CC, Dalziell AH, Billings AC, Germain RR, Pardo M, de Andrade LG, Hedwig D, Keen SC, Shiu Y, Charif RA, Webster MS, Rice AN. Comparative bioacoustics: a roadmap for quantifying and comparing animal sounds across diverse taxa. Biol Rev Camb Philos Soc 2021; 96:1135-1159. [PMID: 33652499 DOI: 10.1111/brv.12695] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/03/2021] [Accepted: 02/05/2021] [Indexed: 12/12/2022]
Abstract
Animals produce a wide array of sounds with highly variable acoustic structures. It is possible to understand the causes and consequences of this variation across taxa with phylogenetic comparative analyses. Acoustic and evolutionary analyses are rapidly increasing in sophistication such that choosing appropriate acoustic and evolutionary approaches is increasingly difficult. However, the correct choice of analysis can have profound effects on output and evolutionary inferences. Here, we identify and address some of the challenges for this growing field by providing a roadmap for quantifying and comparing sound in a phylogenetic context for researchers with a broad range of scientific backgrounds. Sound, as a continuous, multidimensional trait can be particularly challenging to measure because it can be hard to identify variables that can be compared across taxa and it is also no small feat to process and analyse the resulting high-dimensional acoustic data using approaches that are appropriate for subsequent evolutionary analysis. Additionally, terminological inconsistencies and the role of learning in the development of acoustic traits need to be considered. Phylogenetic comparative analyses also have their own sets of caveats to consider. We provide a set of recommendations for delimiting acoustic signals into discrete, comparable acoustic units. We also present a three-stage workflow for extracting relevant acoustic data, including options for multivariate analyses and dimensionality reduction that is compatible with phylogenetic comparative analysis. We then summarize available phylogenetic comparative approaches and how they have been used in comparative bioacoustics, and address the limitations of comparative analyses with behavioural data. Lastly, we recommend how to apply these methods to acoustic data across a range of study systems. In this way, we provide an integrated framework to aid in quantitative analysis of cross-taxa variation in animal sounds for comparative phylogenetic analysis. In addition, we advocate the standardization of acoustic terminology across disciplines and taxa, adoption of automated methods for acoustic feature extraction, and establishment of strong data archival practices for acoustic recordings and data analyses. Combining such practices with our proposed workflow will greatly advance the reproducibility, biological interpretation, and longevity of comparative bioacoustic studies.
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Affiliation(s)
- Karan J Odom
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A
| | - Marcelo Araya-Salas
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Sede del Sur, Universidad de Costa Rica, Golfito, 60701, Costa Rica
| | - Janelle L Morano
- Macaulay Library, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Natural Resources and the Environment, Cornell University, Ithaca, NY, 14853, U.S.A
| | - Russell A Ligon
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A
| | - Gavin M Leighton
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Department of Biology, SUNY Buffalo State, Buffalo, NY, 14222, U.S.A
| | - Conor C Taff
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, U.S.A
| | - Anastasia H Dalziell
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Centre for Sustainable Ecosystem Solutions, University of Wollongong, Northfields Ave, Wollongong, NSW, 2522, Australia
| | - Alexis C Billings
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, U.S.A.,Department of Environmental, Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94709, U.S.A
| | - Ryan R Germain
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, DK-2100, Denmark
| | - Michael Pardo
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, U.S.A
| | - Luciana Guimarães de Andrade
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, U.S.A.,Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A
| | - Daniela Hedwig
- Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A
| | - Sara C Keen
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A.,Department of Geological Sciences, Stanford University, Stanford, CA, 94305, U.S.A
| | - Yu Shiu
- Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A
| | - Russell A Charif
- Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A
| | - Michael S Webster
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, U.S.A.,Macaulay Library, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A
| | - Aaron N Rice
- Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, U.S.A
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Pitnick S, Wolfner MF, Dorus S. Post-ejaculatory modifications to sperm (PEMS). Biol Rev Camb Philos Soc 2020; 95:365-392. [PMID: 31737992 PMCID: PMC7643048 DOI: 10.1111/brv.12569] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022]
Abstract
Mammalian sperm must spend a minimum period of time within a female reproductive tract to achieve the capacity to fertilize oocytes. This phenomenon, termed sperm 'capacitation', was discovered nearly seven decades ago and opened a window into the complexities of sperm-female interaction. Capacitation is most commonly used to refer to a specific combination of processes that are believed to be widespread in mammals and includes modifications to the sperm plasma membrane, elevation of intracellular cyclic AMP levels, induction of protein tyrosine phosphorylation, increased intracellular Ca2+ levels, hyperactivation of motility, and, eventually, the acrosome reaction. Capacitation is only one example of post-ejaculatory modifications to sperm (PEMS) that are widespread throughout the animal kingdom. Although PEMS are less well studied in non-mammalian taxa, they likely represent the rule rather than the exception in species with internal fertilization. These PEMS are diverse in form and collectively represent the outcome of selection fashioning complex maturational trajectories of sperm that include multiple, sequential phenotypes that are specialized for stage-specific functionality within the female. In many cases, PEMS are critical for sperm to migrate successfully through the female reproductive tract, survive a protracted period of storage, reach the site of fertilization and/or achieve the capacity to fertilize eggs. We predict that PEMS will exhibit widespread phenotypic plasticity mediated by sperm-female interactions. The successful execution of PEMS thus has important implications for variation in fitness and the operation of post-copulatory sexual selection. Furthermore, it may provide a widespread mechanism of reproductive isolation and the maintenance of species boundaries. Despite their possible ubiquity and importance, the investigation of PEMS has been largely descriptive, lacking any phylogenetic consideration with regard to divergence, and there have been no theoretical or empirical investigations of their evolutionary significance. Here, we (i) clarify PEMS-related nomenclature; (ii) address the evolutionary origin, maintenance and divergence in PEMS in the context of the protracted life history of sperm and the complex, selective environment of the female reproductive tract; (iii) describe taxonomically widespread types of PEMS: sperm activation, chemotaxis and the dissociation of sperm conjugates; (iv) review the occurence of PEMS throughout the animal kingdom; (v) consider alternative hypotheses for the adaptive value of PEMS; (vi) speculate on the evolutionary implications of PEMS for genomic architecture, sexual selection, and reproductive isolation; and (vii) suggest fruitful directions for future functional and evolutionary analyses of PEMS.
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Affiliation(s)
- Scott Pitnick
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
| | - Mariana F. Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Steve Dorus
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
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