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Beissinger SR, Berg KS. Eviction-driven infanticide and sexually selected adoption and infanticide in a neotropical parrot. Proc Natl Acad Sci U S A 2024; 121:e2317305121. [PMID: 38709919 PMCID: PMC11098109 DOI: 10.1073/pnas.2317305121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 04/04/2024] [Indexed: 05/08/2024] Open
Abstract
Infanticide and adoption have been attributed to sexual selection, where an individual later reproduces with the parent whose offspring it killed or adopted. While sexually selected infanticide is well known, evidence for sexually selected adoption is anecdotal. We report on both behaviors at 346 nests over 27 y in green-rumped parrotlets (Forpus passerinus) in Venezuela. Parrotlets are monogamous with long-term pair bonds, exhibit a strongly male-biased adult sex ratio, and nest in cavities that are in short supply, creating intense competition for nest sites and mates. Infanticide attacks occurred at 256 nests in two distinct contexts: 1) Attacks were primarily committed by nonbreeding pairs (69%) attempting to evict parents from the cavity. Infanticide attacks per nest were positively correlated with population size and evicting pairs never adopted abandoned offspring. Competition for limited nest sites was a primary cause of eviction-driven infanticide, and 2) attacks occurred less frequently at nests where one mate died (31%), was perpetrated primarily by stepparents of both sexes, and was independent of population size. Thus, within a single species and mating system, infanticide occurred in multiple contexts due to multiple drivers. Nevertheless, 48% of stepparents of both sexes adopted offspring, and another 23% of stepfathers exhibited both infanticide and long-term care. Stepfathers were often young males who subsequently nested with widows, reaching earlier ages of first breeding than competitors and demonstrating sexually selected adoption. Adoption and infanticide conferred similar fitness benefits to stepfathers and appeared to be equivalent strategies driven by limited breeding opportunities, male-biased sex ratios, and long-term monogamy.
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Affiliation(s)
- Steven R. Beissinger
- Department of Environmental Science, Policy & Management, University of California, Berkeley, CA94720
- Museum of Vertebrate Zoology, University of California, Berkeley, CA94720
| | - Karl S. Berg
- School of Integrative Biological and Chemical Sciences, University of Texas Rio Grande Valley, Brownsville, TX78520
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McLean CR, Mata A, Kline RJ, Berg KS. Early corticosterone increases vocal complexity in a wild parrot: An organizational role of the hypothalamic-pituitary-adrenal axis in vocal learning? J Neuroendocrinol 2024:e13365. [PMID: 38200690 DOI: 10.1111/jne.13365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/03/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
The neuroendocrinology of vocal learning is exceptionally well known in passerine songbirds. Despite huge life history, genetic and ecological variation across passerines, song learning tends to occur as a result of rises in gonadal and non-gonadal sex steroids that shape telencephalic vocal control circuits and song. Parrots are closely related but independently evolved different cerebral circuits for vocal repertoire acquisition in both sexes that serve a broader suite of social functions and do not appear to be shaped by early androgens or estrogens; instead, parrots begin a plastic phase in vocal development at an earlier life history stage that favors the growth, maturation, and survival functions of corticosteroids. As evidence, corticosterone (CORT) supplements given to wild green-rumped parrotlets (Forpus passerinus) during the first week of vocal babbling resulted in larger vocal repertoires in both sexes in the remaining days before fledging. Here, we replicate this experiment but began treatment 1 week before in development, analyzing both experiments in one model and a stronger test of the organizational effects of CORT on repertoire acquisition. Early CORT treatment resulted in significantly larger repertoires compared to late treatment. Both treatment groups showed weak negative effects on the early, reduplicated stage of babbling and strong, positive effects of CORT on the later, variegated stage. Results are consistent with more formative effects of corticosteroids at earlier developmental stages and a role of the hypothalamic-pituitary-adrenal axis (HPA) in vocal repertoire acquisition. Given the early emergence of speech in human ontogeny, parrots are a promising model for understanding the putative role of the HPA axis in the construction of neural circuits that support language acquisition.
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Affiliation(s)
- Celia R McLean
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, Texas, USA
| | - Astolfo Mata
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
- Centre National de la Recherche Scientifique, Universite de Strasbourg, Strasbourg, France
| | - Richard J Kline
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, Texas, USA
- School of Earth Environmental and Marine Sciences, University of Texas Rio Grande Valley, Brownsville, Texas, USA
| | - Karl S Berg
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, Texas, USA
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Smeele SQ, Tyndel SA, Aplin LM, McElreath MB. Multilevel Bayesian analysis of monk parakeet contact calls shows dialects between European cities. Behav Ecol 2024; 35:arad093. [PMID: 38193012 PMCID: PMC10773303 DOI: 10.1093/beheco/arad093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 09/21/2023] [Accepted: 10/16/2023] [Indexed: 01/10/2024] Open
Abstract
Geographic differences in vocalizations provide strong evidence for animal culture, with patterns likely arising from generations of social learning and transmission. Most studies on the evolution of avian vocal variation have predominantly focused on fixed repertoire, territorial song in passerine birds. The study of vocal communication in open-ended learners and in contexts where vocalizations serve other functions is therefore necessary for a more comprehensive understanding of vocal dialect evolution. Parrots are open-ended vocal production learners that use vocalizations for social contact and coordination. Geographic variation in parrot vocalizations typically take the form of either distinct regional variations known as dialects or graded variation based on geographic distance known as clinal variation. In this study, we recorded monk parakeets (Myiopsitta monachus) across multiple spatial scales (i.e., parks and cities) in their European invasive range. We then compared calls using a multilevel Bayesian model and sensitivity analysis, with this novel approach allowing us to explicitly compare vocalizations at multiple spatial scales. We found support for founder effects and/or cultural drift at the city level, consistent with passive cultural processes leading to large-scale dialect differences. We did not find a strong signal for dialect or clinal differences between parks within cities, suggesting that birds did not actively converge on a group level signal, as expected under the group membership hypothesis. We demonstrate the robustness of our findings and offer an explanation that unifies the results of prior monk parakeet vocalization studies.
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Affiliation(s)
- Simeon Q Smeele
- Cognitive & Cultural Ecology Research Group, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Pl. 6, 04103 Leipzig, Germany
- Ecoscience, Aarhus University, Nordre Ringgade 1, 8000 Aarhus C, Denmark
| | - Stephen A Tyndel
- Cognitive & Cultural Ecology Research Group, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - Lucy M Aplin
- Cognitive & Cultural Ecology Research Group, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton ACT 2601, Australia
- Department of Evolutionary Biology and Environmental Science, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Mary Brooke McElreath
- Cognitive & Cultural Ecology Research Group, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Pl. 6, 04103 Leipzig, Germany
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Eggleston R, Viloria N, Delgado S, Mata A, Guerrero HY, Kline RJ, Beissinger SR, Berg KS. Vocal babbling in a wild parrot shows life history and endocrine affinities with human infants. Proc Biol Sci 2022; 289:20220592. [PMID: 35642373 PMCID: PMC9156925 DOI: 10.1098/rspb.2022.0592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Prelinguistic babbling is a critical phase in infant language development and is best understood in temperate songbirds where it occurs primarily in males at reproductive maturity and is modulated by sex steroids. Parrots of both sexes are icons of tropical vocal plasticity, but vocal babbling is unreported in this group and whether the endocrine system is involved is unknown. Here we show that vocal babbling is widespread in a wild parrot population in Venezuela, ensues in both sexes during the nestling stage, occurs amidst a captive audience of mixed-aged siblings, and is modulated by corticosteroids. Spectrographic analysis and machine learning found phoneme diversity and combinatorial capacity increased precipitously for the first week, thereafter, crystalizing into a smaller repertoire, consistent with the selective attrition model of language development. Corticosterone-treated nestlings differed from unmanipulated birds and sham controls in several acoustic properties and crystallized a larger repertoire post-treatment. Our findings indicate babbling occurs during an early life-history stage in which corticosteroids help catalyse the transition from a universal learning programme to one finely tuned for the prevailing ecological environment, a potentially convergent scenario in human prelinguistic development.
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Affiliation(s)
- Rory Eggleston
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Nurialby Viloria
- Departmento de Biología, Universidad de Carabobo, Valencia, Venezuela
| | - Soraya Delgado
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Astolfo Mata
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Hilda Y. Guerrero
- Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas, Venezuela
| | - Richard J. Kline
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, TX, USA,School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Steven R. Beissinger
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA,Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
| | - Karl S. Berg
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, TX, USA,School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Brownsville, TX, USA
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