1
|
Jiang G, Xue Y, Huang X. Temperature-Induced Sex Differentiation in River Prawn ( Macrobrachium nipponense): Mechanisms and Effects. Int J Mol Sci 2024; 25:1207. [PMID: 38279207 PMCID: PMC10816446 DOI: 10.3390/ijms25021207] [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: 11/30/2023] [Revised: 01/14/2024] [Accepted: 01/15/2024] [Indexed: 01/28/2024] Open
Abstract
Macrobrachium nipponense is gonochoristic and sexually dimorphic. The male prawn grows faster and usually has a larger size than the female. Therefore, a higher male proportion in stock usually results in higher yield. To investigate the impact of temperature on sexual differentiation in M. nipponense, two temperature treatments (26 °C and 31 °C) were conducted. The results showed that compared to the 31 °C treatment (3.20 ± 0.12), the 26 °C treatment displayed a lower female/male ratio (2.20 ± 0.11), which implied that a lower temperature could induce masculinization in M. nipponense. The temperature-sensitive sex differentiation phase was 25-35 days post hatching (DPH) at 26 °C while 15-20 DPH at 31 °C. Transcriptome and qPCR analysis revealed that a lower temperature up-regulated the expression of genes related to androgen secretion, and down-regulated the expressions of genes related to oogonia differentiation. Thirty-one temperature-regulated sex-differentiation genes were identified and the molecular mechanism of temperature-regulated sex differentiation was suggested. The finding of this study indicates that temperature regulation can be proposed as an innovative strategy for improving the culture yield of M. nipponense.
Collapse
Affiliation(s)
- Gang Jiang
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (G.J.); (Y.X.)
| | - Yucai Xue
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (G.J.); (Y.X.)
| | - Xuxiong Huang
- Centre for Research on Environmental Ecology and Fish Nutrition (CREEFN) of the Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; (G.J.); (Y.X.)
- Building of China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology and Joint Research on Mariculture Technology, Shanghai 201306, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China
| |
Collapse
|
2
|
Fuentes MMPB, Santos AJB, Abreu-Grobois A, Briseño-Dueñas R, Al-Khayat J, Hamza S, Saliba S, Anderson D, Rusenko KW, Mitchell NJ, Gammon M, Bentley BP, Beton D, Booth DTB, Broderick AC, Colman LP, Snape RTE, Calderon-Campuzano MF, Cuevas E, Lopez-Castro MC, Flores-Aguirre CD, Mendez de la Cruz F, Segura-Garcia Y, Ruiz-Garcia A, Fossette S, Gatto CR, Reina RD, Girondot M, Godfrey M, Guzman-Hernandez V, Hart CE, Kaska Y, Lara PH, Marcovaldi MAGD, LeBlanc AM, Rostal D, Liles MJ, Wyneken J, Lolavar A, Williamson SA, Manoharakrishnan M, Pusapati C, Chatting M, Mohd Salleh S, Patricio AR, Regalla A, Restrepo J, Garcia R, Santidrián Tomillo P, Sezgin C, Shanker K, Tapilatu F, Turkozan O, Valverde RA, Williams K, Yilmaz C, Tolen N, Nel R, Tucek J, Legouvello D, Rivas ML, Gaspar C, Touron M, Genet Q, Salmon M, Araujo MR, Freire JB, Castheloge VD, Jesus PR, Ferreira PD, Paladino FV, Montero-Flores D, Sozbilen D, Monsinjon JR. Adaptation of sea turtles to climate warming: Will phenological responses be sufficient to counteract changes in reproductive output? GLOBAL CHANGE BIOLOGY 2024; 30:e16991. [PMID: 37905464 DOI: 10.1111/gcb.16991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 11/02/2023]
Abstract
Sea turtles are vulnerable to climate change since their reproductive output is influenced by incubating temperatures, with warmer temperatures causing lower hatching success and increased feminization of embryos. Their ability to cope with projected increases in ambient temperatures will depend on their capacity to adapt to shifts in climatic regimes. Here, we assessed the extent to which phenological shifts could mitigate impacts from increases in ambient temperatures (from 1.5 to 3°C in air temperatures and from 1.4 to 2.3°C in sea surface temperatures by 2100 at our sites) on four species of sea turtles, under a "middle of the road" scenario (SSP2-4.5). Sand temperatures at sea turtle nesting sites are projected to increase from 0.58 to 4.17°C by 2100 and expected shifts in nesting of 26-43 days earlier will not be sufficient to maintain current incubation temperatures at 7 (29%) of our sites, hatching success rates at 10 (42%) of our sites, with current trends in hatchling sex ratio being able to be maintained at half of the sites. We also calculated the phenological shifts that would be required (both backward for an earlier shift in nesting and forward for a later shift) to keep up with present-day incubation temperatures, hatching success rates, and sex ratios. The required shifts backward in nesting for incubation temperatures ranged from -20 to -191 days, whereas the required shifts forward ranged from +54 to +180 days. However, for half of the sites, no matter the shift the median incubation temperature will always be warmer than the 75th percentile of current ranges. Given that phenological shifts will not be able to ameliorate predicted changes in temperature, hatching success and sex ratio at most sites, turtles may need to use other adaptive responses and/or there is the need to enhance sea turtle resilience to climate warming.
Collapse
Affiliation(s)
- M M P B Fuentes
- Marine Turtle Research, Ecology, and Conservation Group, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
| | - A J B Santos
- Marine Turtle Research, Ecology, and Conservation Group, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
| | - A Abreu-Grobois
- Unidad Academica Mazatlan, Instituto de Ciencias del Mar y Limnologia, UNAM, Mazatlan, Sinaloa, Mexico
| | - R Briseño-Dueñas
- Unidad Academica Mazatlan, Instituto de Ciencias del Mar y Limnologia, UNAM, Mazatlan, Sinaloa, Mexico
| | - J Al-Khayat
- Environmental Science Centre, Qatar University, Doha, Qatar
| | - S Hamza
- Environmental Science Centre, Qatar University, Doha, Qatar
| | - S Saliba
- Environmental Science Centre, Qatar University, Doha, Qatar
| | - D Anderson
- Gumbo Limbo Nature Center, Boca Raton, Florida, USA
| | - K W Rusenko
- Gumbo Limbo Nature Center, Boca Raton, Florida, USA
| | - N J Mitchell
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - M Gammon
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - B P Bentley
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, Australia
- Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts, USA
| | - D Beton
- Society for Protection of Turtles, Gonyeli, Northern Cyprus
| | - D T B Booth
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - A C Broderick
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - L P Colman
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - R T E Snape
- Society for Protection of Turtles, Gonyeli, Northern Cyprus
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - M F Calderon-Campuzano
- Programa de Protección y Conservación de Tortugas Marinas, Convenio FONATUR-Instituto de Ciencias del Mar y Limnología-UNAM, Mazatlán, Sinaloa, Mexico
| | - E Cuevas
- Instituto de Investigaciones Oceanologicas, Universidad Autonoma de Baja California, Ensenada, Mexico
| | - M C Lopez-Castro
- Pronatura Península de Yucatán, A. C. Programa para la Conservación de la Tortuga Marina, Mérida, Yucatán, Mexico
| | - C D Flores-Aguirre
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - F Mendez de la Cruz
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Y Segura-Garcia
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - A Ruiz-Garcia
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - S Fossette
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, Australia
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Kensington, Western Australia, Australia
| | - C R Gatto
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - R D Reina
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - M Girondot
- Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique et Evolution, Gif-sur-Yvette, France
| | - M Godfrey
- North Carolina Wildlife Resources Commission, Beaufort, North Carolina, USA
- Duke Marine Laboratory, Nicholas School of Environment, Duke University, Beaufort, North Carolina, USA
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | | | - C E Hart
- Centro de Investigaciones Oceánicas del Mar de Cortés-Gran Acuario de Mazatlán, Mazatlán, Mexico
| | - Y Kaska
- Department of Biology, Faculty of Science, Pamukkale University, Denizli, Turkey
| | - P H Lara
- Fundação Projeto Tamar, Florianópolis, Brazil
| | | | - A M LeBlanc
- Georgia Southern University, Statesboro, Georgia, USA
| | - D Rostal
- Georgia Southern University, Statesboro, Georgia, USA
| | - M J Liles
- Asociacion ProCosta, San Salvador, El Salvador
| | - J Wyneken
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA
| | - A Lolavar
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA
| | - S A Williamson
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA
| | | | | | - M Chatting
- Environmental Science Centre, Qatar University, Doha, Qatar
- School of Civil Engineering, University College Dublin, Dublin, Ireland
| | - S Mohd Salleh
- School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | - A R Patricio
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
- Marine and Environmental Sciences Centre/ARNET-Aquatic Research Network, Ispa-Instituto Universitário de Ciências Psicológicas, Lisbon, Portugal
| | - A Regalla
- Instituto da Biodiversidade e das Áreas Protegidas, Dr. Alfredo Simão da Silva (IBAP), Bissau, Guinea-Bissau
| | - J Restrepo
- Sea Turtle Conservancy, Gainesville, Florida, USA
| | - R Garcia
- Sea Turtle Conservancy, Gainesville, Florida, USA
| | | | - C Sezgin
- Sea Turtle Research, Rescue and Rehabilitation Center (DEKAMER), Mugla, Turkey
| | - K Shanker
- Dakshin Foundation, Bangalore, India
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
| | - F Tapilatu
- Research Center of Pacific Marine Resources-University of Papua (UNIPA), Manokwari, Papua Barat, Indonesia
| | - O Turkozan
- Department of Biology, Faculty of Science, Aydın Adnan Menderes University, Aydın, Turkey
| | - R A Valverde
- Sea Turtle Conservancy, Gainesville, Florida, USA
- Biological Sciences, Southeastern Louisiana University, Hammond, Louisiana, USA
| | - K Williams
- Caretta Research Project, Savannah, Georgia, USA
| | - C Yilmaz
- Hakkari University, Vocational School of Health Services, Hakkari, Turkey
| | - N Tolen
- Universiti Malaysia Terengganu, Kuala Nerus, Malaysia
| | - R Nel
- Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha, South Africa
| | - J Tucek
- Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha, South Africa
| | - D Legouvello
- Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha, South Africa
| | - M L Rivas
- Department of Biology, University of Cadiz, Cadiz, Spain
| | - C Gaspar
- Te Mana O Te Moana, Moorea-Maiao, French Polynesia
| | - M Touron
- Te Mana O Te Moana, Moorea-Maiao, French Polynesia
| | - Q Genet
- Te Mana O Te Moana, Moorea-Maiao, French Polynesia
| | - M Salmon
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA
| | - M R Araujo
- Ministerio de Medio Ambiente y Recursos Naturales, San Salvador, El Salvador
| | - J B Freire
- Fundação Espírito Santense de Tecnologia-FEST, Vitória, Espírito Santo, Brazil
| | | | - P R Jesus
- Econservation Estudos e Projetos Ambientais, Vitória, Espírito Santo, Brazil
| | - P D Ferreira
- Departamento de Gemologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil
| | - F V Paladino
- Purdue University Fort Wayne, Fort Wayne, Indiana, USA
| | | | - D Sozbilen
- Department of Veterinary, Acıpayam Vocational School, Pamukkale University, Denizli, Turkey
| | - J R Monsinjon
- Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Délégation Océan Indien (DOI), Le Port, La Réunion, France
| |
Collapse
|
3
|
Breitenbach AT, Marroquín-Flores RA, Paitz RT, Bowden RM. Experiencing short heat waves early in development changes thermal responsiveness of turtle embryos to later heat waves. J Exp Biol 2023; 226:jeb246235. [PMID: 37661755 PMCID: PMC10560553 DOI: 10.1242/jeb.246235] [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: 06/02/2023] [Accepted: 08/17/2023] [Indexed: 09/05/2023]
Abstract
Although physiological responses to the thermal environment are most frequently investigated using constant temperatures, the incorporation of thermal variability can allow for a more accurate prediction of how thermally sensitive species respond to a rapidly changing climate. In species with temperature-dependent sex determination (TSD), developmental responses to incubation temperature are mediated by several genes involved in gonadal differentiation. Kdm6b and Dmrt1 respond to cool incubation temperatures and are associated with testis development, while FoxL2 and Cyp19A1 respond to warm incubation temperatures and are associated with ovary development. Using fluctuating incubation temperatures, we designed two studies, one investigating how conflicting thermal cues affect the timing of commitment to gonadal development, and another investigating the rapid molecular responses to conflicting thermal cues in the red-eared slider turtle (Trachemys scripta). Using gene expression as a proxy of timing of commitment to gonadal fate, results from the first study show that exposure to high amounts of conflicting thermal cues during development delays commitment to gonadal fate. Results from the second study show that Kdm6b splice variants exhibit differential responses to early heat wave exposure, but rapidly (within 2 days) recover to pre-exposure levels after the heat wave. Despite changes in the expression of Kdm6b splice variants, there was no effect on Dmrt1 expression. Collectively, these findings demonstrate how short exposures to heat early in development can change how embryos respond to heat later in development.
Collapse
Affiliation(s)
- Anthony T. Breitenbach
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Rosario A. Marroquín-Flores
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Ryan T. Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Rachel M. Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| |
Collapse
|
4
|
Catron S, Roth S, Zumpano F, Bintz J, Fordyce JA, Lenhart S, Miller DL, Wyneken J. Modeling the impacts of temperature during nesting seasons on Loggerhead (Caretta caretta) Sea Turtle populations in South Florida. Ecol Modell 2023. [DOI: 10.1016/j.ecolmodel.2023.110363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
|
5
|
Monsinjon JR, Guillon JM, Wyneken J, Girondot M. Thermal reaction norm for sexualization: The missing link between temperature and sex ratio for temperature-dependent sex determination. Ecol Modell 2022. [DOI: 10.1016/j.ecolmodel.2022.110119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
6
|
Cardona L, San Martín J, Benito L, Tomás J, Abella E, Eymar J, Aguilera M, Esteban JA, Tarragó A, Marco A. Global warming facilitates the nesting of the loggerhead turtle on the Mediterranean coast of Spain. Anim Conserv 2022. [DOI: 10.1111/acv.12828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- L. Cardona
- IRBio and Department of Evolutionary Biology, Ecology and Environmental Science, Faculty of Biology University of Barcelona Barcelona Spain
| | | | - L. Benito
- IRBio and Department of Evolutionary Biology, Ecology and Environmental Science, Faculty of Biology University of Barcelona Barcelona Spain
| | - J. Tomás
- Cavanilles Institute of Biodiversity and Evolutionary Biology University of Valencia Valencia Spain
| | - E. Abella
- BETA Technological Center, Universitat de Vic‐ Universitat Central de Catalunya Futurlab‐Can Baumann Vic Spain
| | - J. Eymar
- Conselleria de Agricultura, Desarrollo Rural, Emergencia Climática y Transición Ecológica Dirección General del Medio Natural, Servicio de Vida Silvestre Valencia Spain
| | - M. Aguilera
- BETA Technological Center, Universitat de Vic‐ Universitat Central de Catalunya Futurlab‐Can Baumann Vic Spain
| | | | - A. Tarragó
- Departament d'Acció Climàtica, Alimentació Agenda Rural Generalitat de Catalunya Barcelona Spain
| | - A. Marco
- Estación Biológica de Doñana CSIC Sevilla Spain
| |
Collapse
|
7
|
Camillo CS, Valenzuela N, Johnson SA. Effects of semi-constant temperature on embryonic and hatchling phenotypes of six-tubercled Amazon River turtles, Podocnemis sextuberculata. J Therm Biol 2022; 108:103292. [DOI: 10.1016/j.jtherbio.2022.103292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/21/2022] [Accepted: 07/14/2022] [Indexed: 11/17/2022]
|
8
|
Minor Sea Turtle Nesting Areas May Remain Unnoticed without Specific Monitoring: The Case of the Largest Mediterranean Island (Sicily, Italy). Animals (Basel) 2022; 12:ani12091221. [PMID: 35565647 PMCID: PMC9101241 DOI: 10.3390/ani12091221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/02/2022] [Accepted: 05/03/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Before protecting sea turtles’ nesting sites from coastal development, these sites must be identified and evaluated. This is particularly difficult with minor nesting sites distributed over large areas. We report on the case of Sicily, the largest Mediterranean island with 464 km of sandy shores, where sea turtle nesting activity was basically unknown until recent years when specific projects focused on this topic. This may be the case for many other areas. A total of 323 nests have been reported in the 1944–2021 period (mostly in the last decade). However, the real number of nests occurring annually is still unknown and more research and monitoring is needed. In sea turtles, sex is determined by the incubation temperature, with high temperatures producing more females, and with global warming the scarcity of males may become a problem. Nests in Sicily seem to produce more males and therefore this area may be important for the species’ conservation in the future. Abstract Identifying coastal tracts suitable for sea turtle reproduction is crucial for sea turtle conservation in a context of fast coastal development and climate change. In contrast to nesting aggregations, diffuse nesting is elusive and assessing nesting levels is challenging. A total of 323 nesting events by the loggerhead sea turtle Caretta caretta have been reported in Sicily, the largest Mediterranean island, in the 1944–2021 period, mostly in the last decade. Specific monitoring efforts are the most likely explanation for such an increase and shows that sea turtle nesting may be underestimated or completely ignored in many areas with scattered nesting. The real nesting level along the 464 km sandy shores of Sicily is still unknown and more research is needed. The observed incubation period was relatively long (57 d) suggesting that a majority of males are produced in Sicily, in contrast to the typical female-biased sex ratio of sea turtles. In a context of climate warming producing sex ratios more skewed towards females, the potential of Sicily as a male-producing area should be further investigated. Other reproductive parameters are provided, such as clutch size and hatching and emergence success. A negative effect of relocation on the latter two was observed.
Collapse
|
9
|
Gatto CR, Reina RD. A review of the effects of incubation conditions on hatchling phenotypes in non-squamate reptiles. J Comp Physiol B 2022; 192:207-233. [PMID: 35142902 PMCID: PMC8894305 DOI: 10.1007/s00360-021-01415-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 09/15/2021] [Accepted: 10/03/2021] [Indexed: 11/28/2022]
Abstract
Developing embryos of oviparous reptiles show substantial plasticity in their responses to environmental conditions during incubation, which can include altered sex ratios, morphology, locomotor performance and hatching success. While recent research and reviews have focused on temperature during incubation, emerging evidence suggests other environmental variables are also important in determining hatchling phenotypes. Understanding how the external environment influences development is important for species management and requires identifying how environmental variables exert their effects individually, and how they interact to affect developing embryos. To address this knowledge gap, we review the literature on phenotypic responses in oviparous non-squamate (i.e., turtles, crocodilians and tuataras) reptile hatchlings to temperature, moisture, oxygen concentration and salinity. We examine how these variables influence one another and consider how changes in each variable alters incubation conditions and thus, hatchling phenotypes. We explore how incubation conditions drive variation in hatchling phenotypes and influence adult populations. Finally, we highlight knowledge gaps and suggest future research directions.
Collapse
Affiliation(s)
- Christopher R Gatto
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia.
| | - Richard D Reina
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia
| |
Collapse
|
10
|
Lawson L, Rollinson N. A simple model for the evolution of temperature-dependent sex determination explains the temperature sensitivity of embryonic mortality in imperiled reptiles. CONSERVATION PHYSIOLOGY 2021; 9:coab020. [PMID: 33996099 PMCID: PMC8111383 DOI: 10.1093/conphys/coab020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 08/06/2020] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
A common reptile conservation strategy involves artificial incubation of embryos and release of hatchlings or juveniles into wild populations. Temperature-dependent sex determination (TSD) occurs in most chelonians, permitting conservation managers to bias sex ratios towards females by incubating embryos at high temperatures, ultimately allowing the introduction of more egg-bearing individuals into populations. Here, we revisit classic sex allocation theory and hypothesize that TSD evolved in some reptile groups (specifically, chelonians and crocodilians) because male fitness is more sensitive to condition (general health, vigor) than female fitness. It follows that males benefit more than females from incubation environments that confer high-quality phenotypes, and hence high-condition individuals. We predict that female-producing temperatures, which comprise relatively high incubation temperatures in chelonians and crocodilians, are relatively stressful for embryos and subsequent life stages. We synthesize data from 28 studies to investigate how constant temperature incubation affects embryonic mortality in chelonians with TSD. We find several lines of evidence suggesting that warm, female-producing temperatures are more stressful than cool, male-producing temperatures. Further, we find some evidence that pivotal temperatures (TPiv, the temperature that produces a 1:1 sex ratio) may exhibit a correlated evolution with embryonic thermal tolerance. If patterns of temperature-sensitive embryonic mortality are also indicative of chronic thermal stress that occurs post-hatching, then conservation programs may benefit from incubating eggs close to species-specific TPivs, thus avoiding high-temperature incubation. Indeed, our models predict that, on average, a sex ratio of >75% females can generally be achieved by incubating eggs only 1°C above TPiv. Of equal importance, we provide insight into the enigmatic evolution of TSD in chelonians, by providing support to the hypothesis that TSD evolution is related to the quality of the phenotype conferred by incubation temperature, with males produced in high-quality incubation environments.
Collapse
Affiliation(s)
- Lauren Lawson
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Room 3055, Toronto ON, Canada M5S 3B2
- School of the Environment, University of Toronto, 33 Willcocks St., Suite 1016V, Toronto ON, Canada M5S 3E8
| | - Njal Rollinson
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Room 3055, Toronto ON, Canada M5S 3B2
- School of the Environment, University of Toronto, 33 Willcocks St., Suite 1016V, Toronto ON, Canada M5S 3E8
| |
Collapse
|
11
|
Patrício AR, Hawkes LA, Monsinjon JR, Godley BJ, Fuentes MMPB. Climate change and marine turtles: recent advances and future directions. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01110] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Climate change is a threat to marine turtles that is expected to affect all of their life stages. To guide future research, we conducted a review of the most recent literature on this topic, highlighting knowledge gains and research gaps since a similar previous review in 2009. Most research has been focussed on the terrestrial life history phase, where expected impacts will range from habitat loss and decreased reproductive success to feminization of populations, but changes in reproductive periodicity, shifts in latitudinal ranges, and changes in foraging success are all expected in the marine life history phase. Models have been proposed to improve estimates of primary sex ratios, while technological advances promise a better understanding of how climate can influence different life stages and habitats. We suggest a number of research priorities for an improved understanding of how climate change may impact marine turtles, including: improved estimates of primary sex ratios, assessments of the implications of female-biased sex ratios and reduced male production, assessments of the variability in upper thermal limits of clutches, models of beach sediment movement under sea level rise, and assessments of impacts on foraging grounds. Lastly, we suggest that it is not yet possible to recommend manipulating aspects of turtle nesting ecology, as the evidence base with which to understand the results of such interventions is not robust enough, but that strategies for mitigation of stressors should be helpful, providing they consider the synergistic effects of climate change and other anthropogenic-induced threats to marine turtles, and focus on increasing resilience.
Collapse
Affiliation(s)
- AR Patrício
- MARE - Marine and Environmental Sciences Centre, ISPA - Instituto Universitário, 1149-041 Lisbon, Portugal
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9FE, UK
| | - LA Hawkes
- Hatherley Laboratories, College of Life and Environmental Sciences, University of Exeter, Streatham Campus, Exeter EX4 4PS, UK
| | - JR Monsinjon
- Department of Zoology and Entomology, Rhodes University, Grahamstown 6139, South Africa
| | - BJ Godley
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9FE, UK
| | - MMPB Fuentes
- Marine Turtle Research, Ecology and Conservation Group, Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USA
| |
Collapse
|
12
|
Maurer AS, Seminoff JA, Layman CA, Stapleton SP, Godfrey MH, Reiskind MOB. Population Viability of Sea Turtles in the Context of Global Warming. Bioscience 2021. [DOI: 10.1093/biosci/biab028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Sea turtles present a model for the potential impacts of climate change on imperiled species, with projected warming generating concern about their persistence. Various sea turtle life-history traits are affected by temperature; most strikingly, warmer egg incubation temperatures cause female-biased sex ratios and higher embryo mortality. Predictions of sea turtle resilience to climate change are often focused on how resulting male limitation or reduced offspring production may affect populations. In the present article, by reviewing research on sea turtles, we provide an overview of how temperature impacts on incubating eggs may cascade through life history to ultimately affect population viability. We explore how sex-specific patterns in survival and breeding periodicity determine the differences among offspring, adult, and operational sex ratios. We then discuss the implications of skewed sex ratios for male-limited reproduction, consider the negative correlation between sex ratio skew and genetic diversity, and examine consequences for adaptive potential. Our synthesis underscores the importance of considering the effects of climate throughout the life history of any species. Lethal effects (e.g., embryo mortality) are relatively direct impacts, but sublethal effects at immature life-history stages may not alter population growth rates until cohorts reach reproductive maturity. This leaves a lag during which some species transition through several stages subject to distinct biological circumstances and climate impacts. These perspectives will help managers conceptualize the drivers of emergent population dynamics and identify existing knowledge gaps under different scenarios of predicted environmental change.
Collapse
Affiliation(s)
- Andrew S Maurer
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, in the United States; he is also a research associate with the Jumby Bay Hawksbill Project in Antigua, West Indies
| | - Jeffrey A Seminoff
- Marine Turtle Ecology and Assessment Program, National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center, La Jolla, California, United States
| | - Craig A Layman
- Center for Energy, Environment, and Sustainability, Wake Forest University, in Winston-Salem, North Carolina, in the United States
| | - Seth P Stapleton
- Conservation and animal health sciences, Minnesota Zoo, Apple Valley, Minnesota; he is also an adjunct faculty member in the Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, in Minneapolis, Minnesota, in the United States
| | - Matthew H Godfrey
- North Carolina Wildlife Resources Commission, Raleigh, North Carolina, United States
| | - Martha O Burford Reiskind
- Martha Burford Reiskind is an assistant professor in the Department of Biological Sciences and the director of the Genetics and Genomics Scholars program, North Carolina State University, Raleigh, North Carolina, United States
| |
Collapse
|
13
|
Chatting M, Hamza S, Al-Khayat J, Smyth D, Husrevoglu S, Marshall CD. Feminization of hawksbill turtle hatchlings in the twenty-first century at an important regional nesting aggregation. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Projected climate change is forecasted to have significant effects on biological systems worldwide. Marine turtles in particular may be vulnerable, as the sex of their offspring is determined by their incubating temperature, termed temperature-dependent sex determination. This study aimed to estimate historical, and forecast future, primary sex ratios of hawksbill turtle Eretmochelys imbricata hatchlings at an important nesting ground in northeastern Qatar. Incubation temperatures from the Arabian/Persian Gulf were measured over 2 nesting seasons. Climate data from same period were regressed with nest temperatures to estimate incubation temperatures and hatchling sex ratios for the site from 1993 to 2100. Future hatchling sex ratios were estimated for 2 climate forecasts, one mid-range (SSP245) and one extreme (SSP585). Historical climate data showed female-biased sex ratios of 73.2 ± 12.1% from 1993 to 2017. Female biases from 2018 to 2100 averaged 85.7% ± 6.7% under the mid-range scenario and 87.9% ± 5.4% under the high-range scenario. In addition, predicted female hatchling production was >90% from 2054 and 2052 for SSP245 and SSP585, respectively. These results show that hawksbill primary sex ratios in Qatar are at risk of significant feminization by the year 2100 and that hawksbill turtle incubation temperatures in an extreme, understudied environment are already comparable to those predicted in tropical rookeries during the latter half of the 21st century. These results can help conservationists predict primary sex ratios for hawksbill turtles in the region in the face of 21st-century climate change.
Collapse
Affiliation(s)
- M Chatting
- Environmental Science Center, Qatar University, Doha 2713, Qatar
| | - S Hamza
- Environmental Science Center, Qatar University, Doha 2713, Qatar
| | - J Al-Khayat
- Environmental Science Center, Qatar University, Doha 2713, Qatar
| | - D Smyth
- School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5EY, UK
| | - S Husrevoglu
- Institute of Marine Sciences, Middle East Technical University, Erdemli, Mersin 33731, Turkey
| | - CD Marshall
- Department of Marine Biology, Department of Wildlife and Fisheries Sciences, Gulf Center for Sea Turtle Research, Texas A&M University, Galveston, Texas 77553, USA
| |
Collapse
|
14
|
Carter AL, Janzen FJ. Predicting the effects of climate change on incubation in reptiles: methodological advances and new directions. J Exp Biol 2021; 224:224/Suppl_1/jeb236018. [PMID: 33627463 DOI: 10.1242/jeb.236018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The unprecedented advancement of global climate change is affecting thermal conditions across spatial and temporal scales. Reptiles with temperature-dependent sex determination (TSD) are uniquely vulnerable to even fine-scale variation in incubation conditions and are a model system for investigating the impacts of shifting temperatures on key physiological and life-history traits. The ways in which current and predicted future climatic conditions translate from macro- to ultra-fine scale temperature traces in subterranean nests is insufficiently understood. Reliably predicting the ways in which fine-scale, daily and seasonally fluctuating nest temperatures influence embryonic development and offspring phenotypes is a goal that remains constrained by many of the same logistical challenges that have persisted throughout more than four decades of research on TSD. However, recent advances in microclimate and developmental modeling should allow us to move farther away from relatively coarse metrics with limited predictive capacity and towards a fully mechanistic model of TSD that can predict incubation conditions and phenotypic outcomes for a variety of reptile species across space and time and for any climate scenario.
Collapse
Affiliation(s)
- A L Carter
- Michigan State University, Kellogg Biological Station, 3700 E Gull Lake Drive, Hickory Corners, MI 49060, USA.,Iowa State University, Department of Ecology, Evolution and Organismal Biology, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| | - Fredric J Janzen
- Michigan State University, Kellogg Biological Station, 3700 E Gull Lake Drive, Hickory Corners, MI 49060, USA .,Iowa State University, Department of Ecology, Evolution and Organismal Biology, 2200 Osborn Drive, 251 Bessey Hall, Ames, IA 50011, USA
| |
Collapse
|
15
|
Santidrián Tomillo P, Spotila JR. Temperature-Dependent Sex Determination in Sea Turtles in the Context of Climate Change: Uncovering the Adaptive Significance. Bioessays 2020; 42:e2000146. [PMID: 32896903 DOI: 10.1002/bies.202000146] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/22/2020] [Indexed: 11/11/2022]
Abstract
The adaptive significance of temperature-dependent sex determination (TSD) in reptiles remains unknown decades after TSD was first identified in this group. Concurrently, there is growing concern about the effect that rising temperatures may have on species with TSD, potentially producing extremely biased sex ratios or offspring of only one sex. The current state-of the-art in TSD research on sea turtles is reviewed here and, against current paradigm, it is proposed that TSD provides an advantage under warming climates. By means of coadaptation between early survival and sex ratios, sea turtles are able to maintain populations. When offspring survival declines at high temperatures, the sex that increases future fecundity (females) is produced, increasing resilience to climate warming. TSD could have helped reptiles to survive mass extinctions in the past via this model. Flaws in research on sex determination in sea turtles are also identified and it is suggested that the development of new techniques will revolutionize the field.
Collapse
Affiliation(s)
| | - James R Spotila
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, Pennsylvania, 19104, USA
| |
Collapse
|
16
|
Lamont MM, Johnson D, Carthy RR. The incubation environment of nests deposited by a genetically distinct group of loggerhead sea turtles in Northwest Florida. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
17
|
Pewphong R, Kitana J, Kitana N. Thermosensitive period for sex determination of the tropical freshwater turtle Malayemys macrocephala. Integr Zool 2020; 16:160-169. [PMID: 32762015 DOI: 10.1111/1749-4877.12479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many egg-laying reptiles possess temperature-dependent sex determination (TSD) in which outcome of gonadogenesis is determined by incubation temperature during a temperature-sensitive period of development. Prior studies on Malayemys macrocephala showed that incubation temperatures influence gonadal development and suggested that M. macrocephala exhibits TSD. However, information on the temperature-sensitivity period in this species was unknown until the current study. Turtle eggs were collected from rice fields in central Thailand from December 2016 to February 2017. In the laboratory, eggs were incubated at male-biased temperature (26 °C) and shifted to female-biased temperature (32 °C), or vice versa. Single shift experiments were performed systematically during embryonic stages 13-21. After hatching, sex of individual turtles was determined by histological analysis. We found that the sex determination of M. macrocephala is affected by temperature up to stage 16 of embryonic development.
Collapse
Affiliation(s)
- Rangsima Pewphong
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Jirarach Kitana
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.,BioSentinel Research Group (Special Task Force for Activating Research), Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Noppadon Kitana
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.,BioSentinel Research Group (Special Task Force for Activating Research), Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| |
Collapse
|
18
|
Breitenbach AT, Carter AW, Paitz RT, Bowden RM. Using naturalistic incubation temperatures to demonstrate how variation in the timing and continuity of heat wave exposure influences phenotype. Proc Biol Sci 2020; 287:20200992. [PMID: 32752987 DOI: 10.1098/rspb.2020.0992] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Most organisms are exposed to bouts of warm temperatures during development, yet we know little about how variation in the timing and continuity of heat exposure influences biological processes. If heat waves increase in frequency and duration as predicted, it is necessary to understand how these bouts could affect thermally sensitive species, including reptiles with temperature-dependent sex determination (TSD). In a multi-year study using fluctuating temperatures, we exposed Trachemys scripta embryos to cooler, male-producing temperatures interspersed with warmer, female-producing temperatures (heat waves) that varied in either timing during development or continuity and then analysed resulting sex ratios. We also quantified the expression of genes involved in testis differentiation (Dmrt1) and ovary differentiation (Cyp19A1) to determine how heat wave continuity affects the expression of genes involved in sexual differentiation. Heat waves applied during the middle of development produced significantly more females compared to heat waves that occurred just 7 days before or after this window, and even short gaps in the continuity of a heat wave decreased the production of females. Continuous heat exposure resulted in increased Cyp19A1 expression while discontinuous heat exposure failed to increase expression in either gene over a similar time course. We report that even small differences in the timing and continuity of heat waves can result in drastically different phenotypic outcomes. This strong effect of temperature occurred despite the fact that embryos were exposed to the same number of warm days during a short period of time, which highlights the need to study temperature effects under more ecologically relevant conditions where temperatures may be elevated for only a few days at a time. In the face of a changing climate, the finding that subtle shifts in temperature exposure result in substantial effects on embryonic development becomes even more critical.
Collapse
Affiliation(s)
| | - Amanda W Carter
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996-1610, USA
| | - Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Rachel M Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| |
Collapse
|
19
|
Wyneken J, Salmon M. Linking Ecology, Morphology, and Behavior to Conservation: Lessons Learned from Studies of Sea Turtles. Integr Comp Biol 2020; 60:440-455. [PMID: 32617553 DOI: 10.1093/icb/icaa044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Here we describe examples of studies that have contributed both to a basic understanding of the biology of imperiled marine turtles, and to their management and conservation. Key elements include, first and foremost, correctly identifying species that differ strikingly in their morphology at different life stages because with growth, they change size by several orders of magnitude and have accompanying shape changes. We also review comprehensive field studies documenting the need for management actions to correct abnormal shifts in sex ratios caused by climate change. We highlight the need to describe those perturbations in terms that are clear to regulators and personnel responsible for management and conservation policies. Finally, we review several basic studies that enhance our understanding of how selection has shaped morphological, functional, and performance attributes, and describe how that knowledge can be applied to the tasks required for enhancing species recovery.
Collapse
Affiliation(s)
- Jeanette Wyneken
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991, USA
| | - Michael Salmon
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991, USA
| |
Collapse
|
20
|
Pewphong R, Kitana J, Kitana N. Chronology of Gonadal Development in the Malayan Snail-eating Turtle Malayemys macrocephala. Zool Stud 2020; 59:e20. [PMID: 33262844 PMCID: PMC7688403 DOI: 10.6620/zs.2020.59-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 05/08/2020] [Indexed: 12/16/2022]
Abstract
The snail-eating turtle, Malayemys macrocephala, is a common freshwater turtle that can be used as an animal model for developmental biology. However, a thorough investigation of its development is needed before this species can be used as a model. Thus, this study aimed to examine the gonadal development of M. macrocephala. Turtle eggs were collected from rice fields in Phra Nakhon Si Ayutthaya Province, Thailand, and transported to the laboratory. Eggs were incubated in microprocessor-controlled incubators and randomly dissected on a weekly basis to reveal the developing embryos, then their developmental stage was identified according to Yntema (1968). Primordial germ cells and gonad structure were processed through the paraffin method. Moreover, the dynamics of germ cell proliferation and apoptosis were examined by immunohistochemical detection of proliferating cell nuclear antigen (PCNA) and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), respectively. Examination of the gonad revealed four main stages of gonadal development: (i) germ cell migration, (ii) genital ridge appearance, (iii) testicular formation, and (iv) ovarian formation. In the male turtle (incubated at 26°C), gonad developed into the testis with medullary sex cords starting at Yntema stage 17. In the female turtle (incubated at 32°C), these sex cords then degenerated, followed by cortical development into an ovarian structure starting at Yntema stage 19. Subsequently, testicular and ovarian development occurred independently, and distinct sex organs were apparent at Yntema stage 25. In addition, the presumptive testis showed germ cell proliferation in the medulla at Yntema stages 17, 19, and 25 and germ cell apoptosis in the cortex at Yntema stages 19 and 25. The presumptive ovary showed germ cell proliferation in the cortex at Yntema stages 19 and 25, and germ cell apoptosis in the medulla at Yntema stages 19 and 25.
Collapse
Affiliation(s)
- Rangsima Pewphong
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. E-mail: (NK); (Pewphong); (JK)
| | - Jirarach Kitana
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. E-mail: (NK); (Pewphong); (JK)
- BioSentinel Research Group (Special Task Force for Activating Research), Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Noppadon Kitana
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. E-mail: (NK); (Pewphong); (JK)
- BioSentinel Research Group (Special Task Force for Activating Research), Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| |
Collapse
|
21
|
Abreu-Grobois FA, Morales-Mérida BA, Hart CE, Guillon JM, Godfrey MH, Navarro E, Girondot M. Recent advances on the estimation of the thermal reaction norm for sex ratios. PeerJ 2020; 8:e8451. [PMID: 32181050 PMCID: PMC7060753 DOI: 10.7717/peerj.8451] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/23/2019] [Indexed: 11/20/2022] Open
Abstract
Temperature-dependent sex determination, or TSD, is a widespread phenomenon in reptiles. The shape of the relationship between constant incubation temperature and sex ratio defines the TSD pattern. The TSD pattern is considered a life-history parameter important for conservation because the wider the range of temperatures producing both sexes, the more resilient the species is to climate change impacts. We review the different published equations and methodologies that have been used to model TSD patterns. We describe a new flexible model that allows for an asymmetrical pattern around the pivotal temperature, which is the constant temperature producing both sexes in equal proportions. We show that Metropolis-Hastings with Markov chain produced by a Monte Carlo process has many advantages compared to maximum likelihood and is preferred. Finally, we apply the models to results from incubation experiments using eggs from the marine turtle Lepidochelys olivacea originating in Northeast Indian, East Pacific, and West Atlantic Regional Management Units (RMUs) and find large differences in pivotal temperatures but not in transitional ranges of temperatures.
Collapse
Affiliation(s)
- F Alberto Abreu-Grobois
- Laboratorio de Genética y Banco de Información sobre Tortugas Marinas (BITMAR), Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mazatlán, Sinaloa, Mexico
| | - B Alejandra Morales-Mérida
- Facultad de Ciencias Químicas y Farmacia, Universidad de San Carlos de Guatemala, Guatemala City, Guatemala.,Doctorado en Ciencias Naturales para el Desarrollo (DOCINADE), Instituto Tecnológico de Costa Rica (TEC), Universidad Nacional (UNA), Universidad Estatal a Distancia (UNED), San Jose, Costa Rica.,Laboratoire Écologie, Systématique, Évolution, Université Paris Saclay, Centre National de la Recherche Scientifique, AgroParisTech, Orsay, France
| | - Catherine E Hart
- Grupo Tortuguero de las Californias A.C., La Paz, Baja California Sur, Mexico.,Investigación, Capacitación y Soluciones Ambientas y Sociales A.C., Tepic, Nayarit, Mexico
| | - Jean-Michel Guillon
- Laboratoire Écologie, Systématique, Évolution, Université Paris Saclay, Centre National de la Recherche Scientifique, AgroParisTech, Orsay, France
| | - Matthew H Godfrey
- North Carolina Wildlife Resources Commission, Beaufort, NC, United States of America.,Duke Marine Laboratory, Nicholas School of the Environment, Duke University, Beaufort, NC, United States of America.,Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States of America
| | - Erik Navarro
- Laboratorio de Genética y Banco de Información sobre Tortugas Marinas (BITMAR), Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mazatlán, Sinaloa, Mexico
| | - Marc Girondot
- Laboratoire Écologie, Systématique, Évolution, Université Paris Saclay, Centre National de la Recherche Scientifique, AgroParisTech, Orsay, France
| |
Collapse
|
22
|
Lolavar A, Wyneken J. The impact of sand moisture on the temperature-sex ratio responses of developing loggerhead (Caretta caretta) sea turtles. ZOOLOGY 2019; 138:125739. [PMID: 31954221 DOI: 10.1016/j.zool.2019.125739] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 11/25/2022]
Abstract
All species of sea turtles exhibit a cooler male/warmer female temperature-sex ratio response. Field and experimental studies on loggerhead sea turtle sex ratios suggest that increased sand moisture impacts sea turtle sex ratios with, and perhaps beyond, a cooling effect. This study examines how varying sand moisture impacts the embryo's response to temperature. Across three years, loggerhead (Caretta caretta) sea turtle eggs were incubated at temperatures ranging from 28.0°C to 33.0°C. Groups of eggs were incubated in one of three volumetric moisture contents: low, medium, or high. Temperatures inside the group of eggs were recorded throughout incubation. Hatchlings were raised for 2-3 months and sex was identified laparoscopically. We calculated temperature response curves for groups of eggs incubated at each moisture level. Pivotal temperatures did not different among eggs incubated in different sand moistures. The transitional ranges of temperatures (TRT) for eggs incubated in high moisture and low moisture were narrower than the TRT for eggs incubated in medium moisture. The results of this study are crucial for understanding how sea turtle embryos respond to temperature directly or indirectly under different moisture conditions. Current sex ratio predictions rely on the embryos response to temperature only and may inaccurately estimate sex ratios especially during periods of heavy rainfall or drought.
Collapse
Affiliation(s)
- Alexandra Lolavar
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431-0991, USA.
| | - Jeanette Wyneken
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431-0991, USA.
| |
Collapse
|
23
|
Carter AL, Bodensteiner BL, Iverson JB, Milne‐Zelman CL, Mitchell TS, Refsnider JM, Warner DA, Janzen FJ. Breadth of the thermal response captures individual and geographic variation in temperature‐dependent sex determination. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13410] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Anna L. Carter
- Department of Ecology, Evolution & Organismal Biology Iowa State University Ames IA USA
| | | | | | | | - Timothy S. Mitchell
- Department of Ecology, Evolution & Behavior University of Minnesota Minneapolis MN USA
| | | | - Daniel A. Warner
- Department of Biological Sciences Auburn University Auburn AL USA
| | - Fredric J. Janzen
- Department of Ecology, Evolution & Organismal Biology Iowa State University Ames IA USA
| |
Collapse
|
24
|
Massey MD, Holt SM, Brooks RJ, Rollinson N. Measurement and modelling of primary sex ratios for species with temperature-dependent sex determination. ACTA ACUST UNITED AC 2019; 222:jeb.190215. [PMID: 30352829 DOI: 10.1242/jeb.190215] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/16/2018] [Indexed: 02/04/2023]
Abstract
For many oviparous animals, incubation temperature influences sex through temperature-dependent sex determination (TSD). Although climate change may skew sex ratios in species with TSD, few available methods predict sex under natural conditions, fewer still are based on mechanistic hypotheses of development, and field tests of existing methods are rare. We propose a new approach that calculates the probability of masculinization (PM) in natural nests. This approach subsumes the mechanistic hypotheses describing the outcome of TSD, by integrating embryonic development with the temperature-dependent reaction norm for sex determination. Further, we modify a commonly used method of sex ratio estimation, the constant temperature equivalent (CTE), to provide quantitative estimates of sex ratios. We test our new approaches using snapping turtles (Chelydra serpentina). We experimentally manipulated nests in the field, and found that the PM method is better supported than the modified CTE, explaining 69% of the variation in sex ratios across 27 semi-natural nests. Next, we used the PM method to predict variation in sex ratios across 14 natural nests over 2 years, explaining 67% of the variation. We suggest that the PM approach is effective and broadly applicable to species with TSD, particularly for forecasting how sex ratios may respond to climate change. Interestingly, we also found that the modified CTE explained up to 64% of variation in sex ratios in a Type II TSD species, suggesting that our modifications will be useful for future research. Finally, our data suggest that the Algonquin Park population of snapping turtles possesses resilience to biased sex ratios under climate change.
Collapse
Affiliation(s)
- Melanie D Massey
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada
| | - Sarah M Holt
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Ronald J Brooks
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Njal Rollinson
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada.,School of the Environment, University of Toronto, 33 Willcocks Street, Toronto, ON M5S 3E8, Canada
| |
Collapse
|
25
|
Tezak BM, Sifuentes-Romero I, Wyneken J. A new approach for measuring temperature inside turtle eggs. J Exp Biol 2018; 221:jeb.188698. [DOI: 10.1242/jeb.188698] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/20/2018] [Indexed: 11/20/2022]
Abstract
For turtles, the thermal environment experienced during development plays critical roles in many biological processes. While the temperature inside an egg is assumed to match substrate temperature, many factors like evaporative cooling, metabolic heating, and insulating properties of extra-embryonic components can lead to thermal differences. However, no method, to date, allowed for measurement of embryonic temperature in live chelonian eggs. We designed a thermocouple-based technique to measure embryonic temperature achieving 94 percent survival in Trachemys scripta. This methodology may be applicable to other reptile species. We found that, while temperature in the substrate adjacent to the eggshell accurately reflects internal egg temperature, it differs from air temperature (∼ 2 °C) in a moisture-dependent manner. Our results demonstrate that external egg, but not air temperature is suitable for assessing the effects of temperature on biological processes, critical when considering that the TSD mechanism in turtles occur within a 4° C window.
Collapse
Affiliation(s)
- Boris M. Tezak
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Rd., Boca Raton, FL 33431-0991, USA
| | - Itzel Sifuentes-Romero
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Rd., Boca Raton, FL 33431-0991, USA
| | - Jeanette Wyneken
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Rd., Boca Raton, FL 33431-0991, USA
| |
Collapse
|