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Silver‐Gorges I, Shamblin BM, Ashford M, Bower P, Fuentes MMPB. Potential drivers and implications of a balanced breeding sex ratio in a small population of an imperiled species with environmental sex determination. Ecol Evol 2024; 14:e70166. [PMID: 39224154 PMCID: PMC11366973 DOI: 10.1002/ece3.70166] [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: 06/13/2024] [Revised: 07/24/2024] [Accepted: 07/29/2024] [Indexed: 09/04/2024] Open
Abstract
Small populations of imperiled species are susceptible to the negative consequences of skewed sex-ratios. In imperiled species with environmental sex determination such as sea turtles, examining sex ratios across a range of environments and population abundance levels can provide insight into factors that influence population resilience, which can then be the foci of management plans for these species. Breeding sex ratios (the ratio of actively breeding males to females during a reproductive season; BSRs) extrapolated from genetic parentage analyses are a common approach for enumerating sex ratios in sea turtles. Such analyses also allow for the characterization of multiple paternity within sea turtle clutches, which should reflect BSRs and breeding behaviors. We characterized the first BSR for a breeding assemblage of loggerhead sea turtles (Caretta caretta) belonging to the temperate, low-abundance Northern Gulf of Mexico Recovery Unit using genotypes of 16 microsatellite loci from nesting females and hatchlings. Unlike prior studies at both more-tropical and more-temperate, and higher-abundance, Recovery Units in this region, we found a balanced BSR of 1.3:1 males:female and a low incidence (~17%) of multiple paternity. This suggests that there are relatively few males breeding at this assemblage and within this Recovery Unit. Beaches in this region are expected to produce substantial numbers of male hatchlings based on sand temperature data. The relative dearth of mature males may then be due to hydrologic disturbances that disproportionately affect the fitness and survival of male hatchlings, or due to demographic stochasticity. More work is needed to study the factors that might influence male hatchling production and fitness in this region, particularly as climate change is predicted to lead to feminization in global sea turtle populations. Our work demonstrates the broad utility of characterizing BSRs and other sex ratios across a range of populations in imperiled, environmentally sensitive species.
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Affiliation(s)
- Ian Silver‐Gorges
- Department of Earth, Ocean, and Atmospheric ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Brian M. Shamblin
- Warnell School of Forestry and Natural ResourcesUniversity of GeorgiaAthensGeorgiaUSA
| | - Mason Ashford
- Department of Earth, Ocean, and Atmospheric ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Paityn Bower
- Department of Earth, Ocean, and Atmospheric ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Mariana M. P. B. Fuentes
- Department of Earth, Ocean, and Atmospheric ScienceFlorida State UniversityTallahasseeFloridaUSA
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Vella A, Vella N. Conservation Genetics of the Loggerhead Sea Turtle, Caretta caretta, from the Central Mediterranean: An Insight into the Species' Reproductive Behaviour in Maltese Waters. Animals (Basel) 2023; 14:137. [PMID: 38200868 PMCID: PMC10778046 DOI: 10.3390/ani14010137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Loggerhead sea turtle, Caretta caretta (Linnaeus, 1758), nestlings were investigated through specimens found dead either after hatching or unhatched (n = 120) from eight nests around the Maltese islands (Central Mediterranean). Molecular genetics was used to conduct maternity and paternity tests of the collected specimens utilizing expanded mitochondrial DNA sequences from the control region (858 bp) and 25 microsatellite loci (12 dinucleotide loci and 13 tetranucleotide loci). Mitochondrial data produced two haplotypes, CC-A2.1 and CC-A3.1, with the most common haplotype being present in seven nests. Microsatellite data revealed the identity of six different females that were involved in the deposition of the eggs in the eight turtle nests analysed. This confirms that two females laid multiple nests. Additionally, microsatellite data allowed for the determination of multiple paternity, with one clutch being sired by two fathers. These results are useful for monitoring the genetic diversity of loggerhead sea turtle nestlings and of the turtle mothers and fathers contributing to future turtle offspring, which rely on Maltese sandy beaches for their successful start to life. Effective conservation management benefits from merging scientific knowledge with effective measures at potential nesting sites to avoid losses of nestlings caused by human negligence.
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Affiliation(s)
- Adriana Vella
- Conservation Biology Research Group, Department of Biology, Faculty of Science, University of Malta, MSD 2080 Msida, Malta
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Lasala JA, Macksey MC, Mazzarella KT, Main KL, Foote JJ, Tucker AD. Forty years of monitoring increasing sea turtle relative abundance in the Gulf of Mexico. Sci Rep 2023; 13:17213. [PMID: 37821522 PMCID: PMC10567714 DOI: 10.1038/s41598-023-43651-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023] Open
Abstract
Longitudinal data sets for population abundance are essential for studies of imperiled organisms with long life spans or migratory movements, such as marine turtles. Population status trends are crucial for conservation managers to assess recovery effectiveness. A direct assessment of population growth is the enumeration of nesting numbers and quantifying nesting attempts (successful nests/unsuccessful attempts) and emergence success (number of hatchlings leaving the nest) because of the substantial annual variations due to nest placement, predation, and storm activity. We documented over 133,000 sea turtle crawls for 50.9 km of Florida Gulf of Mexico coastline from 1982 to 2021 for a large loggerhead turtle nesting aggregation and a recovering remnant population of green sea turtles. Over time both species have emerged to nest significantly earlier in the year and green sea turtle nesting seasons have extended. Nest counts and hatchling production for both species have significantly increased, but the rate of emergence success of hatchlings leaving nests has not changed for loggerheads and has declined for green sea turtles. Sea level rise and coastal developments undoubtedly influence coastal habitats in the long-term, impacting nest site selection and potential recruitment from the loss of emerged hatchlings. However, the present indications for steady Gulf of Mexico recovery of loggerhead and green sea turtles counter findings of the Florida Atlantic coasts. This study indicates that effective conservation practices can be detected within time scales of 1-2 turtle generations.
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Affiliation(s)
- Jacob Andrew Lasala
- Sea Turtle Conservation and Research Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA.
| | - Melissa C Macksey
- Sea Turtle Conservation and Research Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
| | - Kristen T Mazzarella
- Sea Turtle Conservation and Research Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
| | - Kevan L Main
- Sea Turtle Conservation and Research Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
| | - Jerris J Foote
- Sea Turtle Conservation and Research Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
- Parks, Recreation and Natural Resources, Sarasota County, 1660 Ringling Boulevard, Sarasota, FL, 34236, USA
| | - Anton D Tucker
- Sea Turtle Conservation and Research Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
- Marine Science Program, Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Kensington, WA, Australia
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González-Cortés L, Labastida-Estrada E, Karam-Martínez SG, Montoya-Márquez JA, Islas-Villanueva V. Within-season shifts in multiple paternity patterns in mass-nesting olive ridley sea turtles. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Multiple paternity is common to all sea turtle species, but its causes and consequences are hard to ascertain and the behaviors and success of males difficult to observe. This study aims to describe patterns of multiple paternity for olive ridley turtles Lepidochelys olivacea at Playa de Escobilla, an ‘arribada’ (mass-nesting) site on the Mexican Pacific coast with over a million clutches laid each reproductive season. A total of 15 females and their hatchlings were sampled during 3 arribada events which occurred over the 2016-2017 nesting season. Females and hatchlings (N = 329) were genotyped at 5 microsatellite loci, from which we inferred the alleles of 46 contributing males. Multiple paternity was detected in 60% of the analyzed clutches, which were sired by a range of 2 to 7 males. Multiple paternity rates differed significantly across arribada events, suggesting more males achieved fertilizations earlier in the breeding season. Paternal contribution in 6 of the clutches with multiple paternity was skewed towards a single male; the remaining clutches had a homogeneous male contribution. However, our results are based on relatively small within-arribada sample sizes. The frequency of multiple paternity among turtle clutches laid on this arribada beach could be related to the density of breeding individuals in the reproductive patch off Playa de Escobilla, rather than to the nesting population size or female size.
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Affiliation(s)
- L González-Cortés
- Programa de Maestría en Ciencias: Ecología Marina, División de Estudios de Posgrado, Universidad del Mar, Campus Puerto Ángel, Ciudad Universitaria s/n, Oaxaca 70902, Mexico
| | - E Labastida-Estrada
- Programa de Maestría en Ciencias: Ecología Marina, División de Estudios de Posgrado, Universidad del Mar, Campus Puerto Ángel, Ciudad Universitaria s/n, Oaxaca 70902, Mexico
| | - SG Karam-Martínez
- Instituto de Recursos, Universidad del Mar, Campus Puerto Ángel, Ciudad Universitaria s/n, Oaxaca 70902, Mexico
| | - JA Montoya-Márquez
- Instituto de Recursos, Universidad del Mar, Campus Puerto Ángel, Ciudad Universitaria s/n, Oaxaca 70902, Mexico
| | - V Islas-Villanueva
- CONACYT, Universidad del Mar, Campus Puerto Ángel, Ciudad Universitaria s/n, Oaxaca 70902, Mexico
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