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Horne JB, Frey A, Gaos AR, Martin S, Dutton PH. Non-random mating within an Island rookery of Hawaiian hawksbill turtles: demographic discontinuity at a small coastline scale. R Soc Open Sci 2023; 10:221547. [PMID: 37206959 PMCID: PMC10189603 DOI: 10.1098/rsos.221547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/26/2023] [Indexed: 05/21/2023]
Abstract
Hawksbill sea turtles (Eretmochelys imbricata) from the Hawaiian archipelago form a small and genetically isolated population, consisting of only a few tens of individuals breeding annually. Most females nest on the island of Hawai'i, but little is known about the demographics of this rookery. This study used genetic relatedness, inferred from 135 microhaplotype markers, to determine breeding sex-ratios, estimate female nesting frequency and assess relationships between individuals nesting on different beaches. Samples were collected during the 2017 nesting season and final data included 13 nesting females and 1002 unhatched embryos, salvaged from 41 nests, of which 13 had no observed mother. Results show that most females used a single nesting beach laying 1-5 nests each. From female and offspring alleles, the paternal genotypes of 12 breeding males were reconstructed and many showed high relatedness to their mates. Pairwise relatedness of offspring revealed one instance of polygyny but otherwise suggested a 1 : 1 breeding-sex ratio. Relatedness analysis and spatial-autocorrelation of genotypes indicate that turtles from different nesting areas do not regularly interbreed, suggesting that strong natal homing tendencies in both sexes result in non-random mating across the study area. Complexes of nearby nesting beaches also showed unique patterns of inbreeding across loci, further indicating that Hawaiian hawksbill turtles have demographically discontinuous nesting populations separated by only tens of km.
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Affiliation(s)
- John B. Horne
- Southwest Fisheries Science Center, NOAA-Fisheries, La Jolla, CA, USA
| | - Amy Frey
- Southwest Fisheries Science Center, NOAA-Fisheries, La Jolla, CA, USA
| | - Alexander R. Gaos
- Pacific Islands Fisheries Science Center, NOAA-Fisheries, Honolulu, HI, USA
| | - Summer Martin
- Pacific Islands Fisheries Science Center, NOAA-Fisheries, Honolulu, HI, USA
| | - Peter H. Dutton
- Southwest Fisheries Science Center, NOAA-Fisheries, La Jolla, CA, USA
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Brunson S, Gaos AR, Kelly IK, Van Houtan KS, Swimmer Y, Hargrove S, Balazs GH, Work TM, Jones TT. Three decades of stranding data reveal insights into endangered hawksbill sea turtles in Hawai‘i&dagger. ENDANGER SPECIES RES 2022. [DOI: 10.3354/esr01167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Hawksbill sea turtles Eretmochelys imbricata inhabiting the Hawaiian Islands are extremely rare and listed as endangered under the US Endangered Species Act. The paucity of data on basic hawksbill ecology continues to hinder effective management of the species. We analyzed stranding data collected between 1984 and 2018 to gain insights into the distribution, demography, and conservation challenges facing hawksbills in Hawai‘i. In doing so, we present a comprehensive description of the population across developmental stages and rank threats that may be impeding their successful recovery. Over the >30 yr data set, we recorded a total of only 111 juvenile and adult hawksbill stranding events. Interactions with nearshore recreational fishing gear were documented for a large proportion (48.6%) of stranding events in the Hawaiian Islands, identifying this as the primary management challenge for the species. Stranding events were biased towards females (female to male sex ratio of 4.8:1.0), which may be indicative of the population as a whole. Even though the majority of hawksbills nest on the islands of Hawai‘i Moloka‘i, and Maui, the greatest number of juvenile to adult strandings was found to be on the island of Oahu (n = 47). Temporal distribution of the majority of adult hawksbill strandings (72.2%) occurred during a 4 mo period between June and September. We discuss these and other findings that help identify future research and conservation efforts to mitigate anthropogenic threats in Hawai‘i for this enigmatic population.
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Affiliation(s)
- S Brunson
- NOAA Fisheries, Pacific Islands Fisheries Science Center, Marine Turtle Biology and Assessment Program, 1845 Wasp Boulevard, Building 176, Honolulu, Hawai‘i 96818, USA
| | - AR Gaos
- NOAA Fisheries, Pacific Islands Fisheries Science Center, Marine Turtle Biology and Assessment Program, 1845 Wasp Boulevard, Building 176, Honolulu, Hawai‘i 96818, USA
| | - IK Kelly
- NOAA Fisheries, Pacific Islands Regional Office, 1845 Wasp Boulevard, Building 176, Honolulu, Hawai‘i 96818, USA
| | - KS Van Houtan
- Duke University, Nicholas School of the Environment, Box 90328, Durham, North Carolina 27708, USA
| | - Y Swimmer
- NOAA Fisheries, Pacific Islands Fisheries Science Center, Fisheries Resources and Monitoring Division, 1845 Wasp Boulevard, Building 176, Honolulu, Hawai‘i 96818, USA
| | - S Hargrove
- NOAA Fisheries, Southeast Fisheries Science Center, Office of Protected Resources, Marine Mammal and Sea Turtle Conservation Division, 75 Virginia Beach Drive, Miami, Florida 33149, USA
| | - GH Balazs
- Golden Honu Services of Oceania, 992 Awa’awa’anoa Place, Honolulu, Hawai‘i 96825, USA
| | - TM Work
- US Geological Survey, National Wildlife Health Center, Honolulu Field Station, 300 Ala Moana Blvd., Room 5-231, Honolulu, Hawai‘i 96850, USA
| | - TT Jones
- NOAA Fisheries, Pacific Islands Fisheries Science Center, Fisheries Resources and Monitoring Division, 1845 Wasp Boulevard, Building 176, Honolulu, Hawai‘i 96818, USA
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Liles MJ, Peterson TR, Seminoff JA, Gaos AR, Altamirano E, Henríquez AV, Gadea V, Chavarría S, Urteaga J, Wallace BP, Peterson MJ. Potential limitations of behavioral plasticity and the role of egg relocation in climate change mitigation for a thermally sensitive endangered species. Ecol Evol 2019; 9:1603-1622. [PMID: 30847059 PMCID: PMC6392375 DOI: 10.1002/ece3.4774] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 10/12/2018] [Accepted: 11/05/2018] [Indexed: 01/18/2023] Open
Abstract
Anthropogenic climate change is widely considered a major threat to global biodiversity, such that the ability of a species to adapt will determine its likelihood of survival. Egg-burying reptiles that exhibit temperature-dependent sex determination, such as critically endangered hawksbill turtles (Eretmochelys imbricata), are particularly vulnerable to changes in thermal regimes because nest temperatures affect offspring sex, fitness, and survival. It is unclear whether hawksbills possess sufficient behavioral plasticity of nesting traits (i.e., redistribution of nesting range, shift in nesting phenology, changes in nest-site selection, and adjustment of nest depth) to persist within their climatic niche or whether accelerated changes in thermal conditions of nesting beaches will outpace phenotypic adaption and require human intervention. For these reasons, we estimated sex ratios and physical condition of hatchling hawksbills under natural and manipulated conditions and generated and analyzed thermal profiles of hawksbill nest environments within highly threatened mangrove ecosystems at Bahía de Jiquilisco, El Salvador, and Estero Padre Ramos, Nicaragua. Hawksbill clutches protected in situ at both sites incubated at higher temperatures, yielded lower hatching success, produced a higher percentage of female hatchlings, and produced less fit offspring than clutches relocated to hatcheries. We detected cooler sand temperatures in woody vegetation (i.e., coastal forest and small-scale plantations of fruit trees) and hatcheries than in other monitored nest environments, with higher temperatures at the deeper depth. Our findings indicate that mangrove ecosystems present a number of biophysical (e.g., insular nesting beaches and shallow water table) and human-induced (e.g., physical barriers and deforestation) constraints that, when coupled with the unique life history of hawksbills in this region, may limit behavioral compensatory responses by the species to projected temperature increases at nesting beaches. We contend that egg relocation can contribute significantly to recovery efforts in a changing climate under appropriate circumstances.
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Affiliation(s)
- Michael J. Liles
- Asociación ProCostaSan SalvadorEl Salvador
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Tarla Rai Peterson
- Department of Communication, Environmental Science and Engineering ProgramUniversity of Texas at El PasoEl PasoTexas
| | - Jeffrey A. Seminoff
- National Oceanic and Atmospheric Administration – National Marine Fisheries ServiceSouthwest Fisheries Science CenterLa JollaCalifornia
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Alexander R. Gaos
- Department of BiologySan Diego State UniversitySan DiegoCalifornia
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Eduardo Altamirano
- Fauna and Flora InternationalManaguaNicaragua
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Ana V. Henríquez
- Asociación ProCostaSan SalvadorEl Salvador
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Velkiss Gadea
- Fauna and Flora InternationalManaguaNicaragua
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Sofía Chavarría
- Asociación ProCostaSan SalvadorEl Salvador
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - José Urteaga
- School of Earth, Energy & Environmental SciencesStanford UniversityStanfordCalifornia
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Bryan P. Wallace
- Conservation Science Partners, Inc.Fort CollinsColorado
- Nicholas School of the EnvironmentDuke University Marine LabBeaufortNorth Carolina
- Eastern Pacific Hawksbill InitiativeSan DiegoCalifornia
| | - Markus J. Peterson
- Department of Biological SciencesUniversity of Texas at El PasoEl PasoTexas
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5
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Gaos AR, Lewison RL, Jensen MP, Liles MJ, Henriquez A, Chavarria S, Pacheco CM, Valle M, Melero D, Gadea V, Altamirano E, Torres P, Vallejo F, Miranda C, LeMarie C, Lucero J, Oceguera K, Chácon D, Fonseca L, Abrego M, Seminoff JA, Flores EE, Llamas I, Donadi R, Peña B, Muñoz JP, Ruales DA, Chaves JA, Otterstrom S, Zavala A, Hart CE, Brittain R, Alfaro-Shigueto J, Mangel J, Yañez IL, Dutton PH. Natal foraging philopatry in eastern Pacific hawksbill turtles. R Soc Open Sci 2017; 4:170153. [PMID: 28878969 PMCID: PMC5579084 DOI: 10.1098/rsos.170153] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 07/26/2017] [Indexed: 06/07/2023]
Abstract
The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.
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Affiliation(s)
- Alexander R. Gaos
- Department of Biology, San Diego State University, San Diego, CA, USA
- Graduate Group in Ecology, University of California Davis, Davis, CA, USA
- Marine Mammal and Turtle Division, Ocean Associates Inc., under contract to the Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | | | - Michael P. Jensen
- Marine Mammal and Turtle Division, Ocean Associates Inc., under contract to the Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
| | - Michael J. Liles
- Department of Biology, University of Texas at El Paso, El Paso, TX, USA
- ProCosta, San Salvador, El Salvador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Ana Henriquez
- ProCosta, San Salvador, El Salvador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Sofia Chavarria
- ProCosta, San Salvador, El Salvador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Carlos Mario Pacheco
- ProCosta, San Salvador, El Salvador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Melissa Valle
- ProCosta, San Salvador, El Salvador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - David Melero
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Velkiss Gadea
- Marine Turtles Department, Fauna & Flora International, Managua, Nicaragua
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Eduardo Altamirano
- Marine Turtles Department, Fauna & Flora International, Managua, Nicaragua
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Perla Torres
- Instituto de Ciencias del Mar y Limnología, Unidad Académica Mazatlán, Universidad Nacional de Mexico, Mazatlán, Mexico
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Felipe Vallejo
- Equilibrio Azul, Quito, Ecuador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Cristina Miranda
- Equilibrio Azul, Quito, Ecuador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Carolina LeMarie
- Equilibrio Azul, Quito, Ecuador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Jesus Lucero
- Grupo Tortuguero de las Californias, A.C, La Paz, Mexico
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Karen Oceguera
- Grupo Tortuguero de las Californias, A.C, La Paz, Mexico
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Didiher Chácon
- Latin American Sea Turtles, Tibás, Costa Rica
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Luis Fonseca
- Latin American Sea Turtles, Tibás, Costa Rica
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Marino Abrego
- Conservación de Recursos Costeros y Marinos, Ministerio del Ambiente de Panamá, Panama City, Panama
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Jeffrey A. Seminoff
- Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Eric E. Flores
- Sistema Nacional de Investigación, Panama City, Panama
- Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Panama City, Panama
| | - Israel Llamas
- Campamento Tortuguero Mayto, A.C., Mayto, Mexico
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | | | - Bernardo Peña
- Conservación de Recursos Costeros y Marinos, Ministerio del Ambiente de Panamá, Panama City, Panama
| | - Juan Pablo Muñoz
- Marine Ecology Department, Universidad San Francisco de Quito/Galapagos Science Center, San Cristóbal, Galapagos Archipelago, Ecuador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Daniela Alarcòn Ruales
- Marine Ecology Department, Universidad San Francisco de Quito/Galapagos Science Center, San Cristóbal, Galapagos Archipelago, Ecuador
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Jaime A. Chaves
- Marine Ecology Department, Universidad San Francisco de Quito/Galapagos Science Center, San Cristóbal, Galapagos Archipelago, Ecuador
| | - Sarah Otterstrom
- Paso Pacifico, Managua, Nicaragua
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Alan Zavala
- Unidad Sinaloa, Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Sinaloa, Mexico
- Instituto Politécnico Nacional, Sinaloa, Mexico
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Catherine E. Hart
- Red Tortuguera, A.C, Guayabitos, Mexico
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Rachel Brittain
- Akazul, La Barrona, Guatemala
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Joanna Alfaro-Shigueto
- Marine Turtle Research Group, School of Biosciences, University of Exeter, Penryn, UK
- Marine Biology Department, Universidad Cientifica del Sur, Lima, Peru
- ProDelphinus, Lima, Peru
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | - Jeffrey Mangel
- Marine Turtle Research Group, School of Biosciences, University of Exeter, Penryn, UK
- Eastern Pacific Hawksbill Initiative, San Diego, CA, USA
| | | | - Peter H. Dutton
- Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
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6
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Gaos AR, Lewison RL, Liles MJ, Gadea V, Altamirano E, Henríquez AV, Torres P, Urteaga J, Vallejo F, Baquero A, LeMarie C, Muñoz JP, Chaves JA, Hart CE, Peña de Niz A, Chácon D, Fonseca L, Otterstrom S, Yañez IL, LaCasella EL, Frey A, Jensen MP, Dutton PH. Hawksbill turtle terra incognita: conservation genetics of eastern Pacific rookeries. Ecol Evol 2016; 6:1251-64. [PMID: 26941950 PMCID: PMC4761781 DOI: 10.1002/ece3.1897] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/21/2015] [Accepted: 11/26/2015] [Indexed: 11/05/2022] Open
Abstract
Prior to 2008 and the discovery of several important hawksbill turtle (Eretmochelys imbricata) nesting colonies in the EP (Eastern Pacific), the species was considered virtually absent from the region. Research since that time has yielded new insights into EP hawksbills, salient among them being the use of mangrove estuaries for nesting. These recent revelations have raised interest in the genetic characterization of hawksbills in the EP, studies of which have remained lacking to date. Between 2008 and 2014, we collected tissue samples from 269 nesting hawksbills at nine rookeries across the EP and used mitochondrial DNA sequences (766 bp) to generate the first genetic characterization of rookeries in the region. Our results inform genetic diversity, population differentiation, and phylogeography of the species. Hawksbills in the EP demonstrate low genetic diversity: We identified a total of only seven haplotypes across the region, including five new and two previously identified nesting haplotypes (pooled frequencies of 58.4% and 41.6%, respectively), the former only evident in Central American rookeries. Despite low genetic diversity, we found strong stock structure between the four principal rookeries, suggesting the existence of multiple populations and warranting their recognition as distinct management units. Furthermore, haplotypes EiIP106 and EiIP108 are unique to hawksbills that nest in mangrove estuaries, a behavior found only in hawksbills along Pacific Central America. The detected genetic differentiation supports the existence of a novel mangrove estuary "reproductive ecotype" that may warrant additional conservation attention. From a phylogeographic perspective, our research indicates hawksbills colonized the EP via the Indo-Pacific, and do not represent relict populations isolated from the Atlantic by the rising of the Panama Isthmus. Low overall genetic diversity in the EP is likely the combined result of few rookeries, extremely small reproductive populations and evolutionarily recent colonization events. Additional research with larger sample sizes and variable markers will help further genetic understanding of hawksbill turtles in the EP.
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