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Kynoch C, Paladino FV, Spotila JR, Santidrián Tomillo P. Variability in thermal tolerance of clutches from different mothers indicates adaptation potential to climate warming in sea turtles. GLOBAL CHANGE BIOLOGY 2024; 30:e17447. [PMID: 39098999 DOI: 10.1111/gcb.17447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 06/19/2024] [Accepted: 07/02/2024] [Indexed: 08/06/2024]
Abstract
The current climate warming is a challenge to biodiversity that could surpass the adaptation capacity of some species. Hence, understanding the means by which populations undergo an increase in their thermal tolerance is critical to assess how they could adapt to climate warming. Specifically, sea turtle populations could respond to increasing temperatures by (1) colonizing new nesting areas, (2) nesting during cooler times of the year, and/or (3) by increasing their thermal tolerance. Differences in thermal tolerance of clutches laid by different females would indicate that populations have the potential to adapt by natural selection. Here, we used exhaustive information on nest temperatures and hatching success of leatherback turtle (Dermochelys coriacea) clutches over 14 years to assess the occurrence of individual variability in thermal tolerance among females. We found an effect of temperature, year, and the interaction between female identity and nest temperature on hatching success, indicating that clutches laid by different females exhibited different levels of vulnerability to high temperatures. If thermal tolerance is a heritable trait, individuals with higher thermal tolerances could have greater chances of passing their genes to following generations, increasing their frequency in the population. However, the high rate of failure of clutches at temperatures above 32°C suggests that leatherback turtles are already experiencing extreme heat stress. A proper understanding of mechanisms of adaptation in populations to counteract changes in climate could greatly contribute to future conservation of endangered populations in a rapidly changing world.
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Affiliation(s)
- Camille Kynoch
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
| | - Frank V Paladino
- The Leatherback Trust, Goldring-Gund Marine Biology Station, Playa Grande, Costa Rica
- Department of Biology, Purdue University Fort Wayne, Fort Wayne, Indiana, USA
| | - James R Spotila
- The Leatherback Trust, Goldring-Gund Marine Biology Station, Playa Grande, Costa Rica
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, Pennsylvania, USA
| | - Pilar Santidrián Tomillo
- Centre Oceanogràfic de les Balears, Instituto Español de Oceanografía (IEO, CSIC), Palma de Mallorca, Spain
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2
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Tilley HB, Murphy D, Wierucka K, Wong TC, Surreault-Châble A, Mumby HS. Physical activity and temperature changes of Asian elephants (Elephas maximus) participating in eco-tourism activities and elephant polo. PLoS One 2024; 19:e0300373. [PMID: 38696403 PMCID: PMC11065253 DOI: 10.1371/journal.pone.0300373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 02/26/2024] [Indexed: 05/04/2024] Open
Abstract
Captive and domestic animals are often required to engage in physical activity initiated or organised by humans, which may impact their body temperature, with consequences for their health and welfare. This is a particular concern for animals such as elephants that face thermoregulatory challenges because of their body size and physiology. Using infrared thermography, we measured changes in skin temperature associated with two types of physical activity in ten female Asian elephants (Elephas maximus) at an eco-tourism lodge in Nepal. Six elephants took part in an activity relatively unfamiliar to the elephants-a polo tournament-and four participated in more familiar ecotourism activities. We recorded skin temperatures for four body regions affected by the activities, as well as an average skin temperature. Temperature change was used as the response variable in the analysis and calculated as the difference in elephant temperature before and after activity. We found no significant differences in temperature change between the elephants in the polo-playing group and those from the non-polo playing group. However, for both groups, when comparing the average skin body temperature and several different body regions, we found significant differences in skin temperature change before and after activity. The ear pinna was the most impacted region and was significantly different to all other body regions. This result highlights the importance of this region in thermoregulation for elephants during physical activity. However, as we found no differences between the average body temperatures of the polo and non-polo playing groups, we suggest that thermoregulatory mechanisms can counteract the effects of both physical activities the elephants engaged in.
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Affiliation(s)
- Hannah B. Tilley
- Applied Behavioural Ecology and Conservation Lab, Area of Ecology and Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Derek Murphy
- Applied Behavioural Ecology and Conservation Lab, Area of Ecology and Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR
- German Primate Centre—Leibniz Institute for Primate Research, Cognitive Ethology Laboratory, Göttingen, Germany
- Department for Primate Cognition, Johann-Friedrich-Blumenbach Institute, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Kaja Wierucka
- Applied Behavioural Ecology and Conservation Lab, Area of Ecology and Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR
- German Primate Center–Leibniz Institute for Primate Research, Behavioural Ecology and Sociobiology Unit, Göttingen, Germany
| | - Tsz Ching Wong
- Applied Behavioural Ecology and Conservation Lab, Area of Ecology and Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Annaëlle Surreault-Châble
- Laboratoire Ethologie Cognition Développement, Université Paris Nanterre, Paris, France
- Le PAL, Saint-Pourçain-sur-Besbre, Allier, France
| | - Hannah S. Mumby
- Applied Behavioural Ecology and Conservation Lab, Area of Ecology and Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR
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3
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Arostegui MC, Shero MR, Frank LR, Berquist RM, Braun CD. An enigmatic pelagic fish with internalized red muscle: A future regional endotherm or forever an ectotherm? JOURNAL OF FISH BIOLOGY 2023; 102:1311-1326. [PMID: 36911991 DOI: 10.1111/jfb.15375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 03/08/2023] [Indexed: 06/09/2023]
Abstract
Ectothermy and endothermy in extant fishes are defined by distinct integrated suites of characters. Although only ⁓0.1% of fishes are known to have endothermic capacity, recent discoveries suggest that there may still be uncommon pelagic fish species with yet to be discovered endothermic traits. Among the most rarely encountered marine fishes, the louvar Luvarus imperialis is a remarkable example of adaptive evolution as the only extant pelagic species in the order Acanthuriformes (including surgeonfishes, tangs, unicornfishes and Moorish idol). Magnetic resonance imaging and gross necropsy did not yield evidence of cranial or visceral endothermy but revealed a central-posterior distribution of myotomal red muscle that is a mixture of the character states typifying ectotherms (lateral-posterior) and red muscle endotherms (central-anterior). Dissection of a specimen confirmed, and an osteological proxy supported, that L. imperialis has not evolved the vascular rete that is vital to retaining heat in the red muscle. The combination of presumably relying on caudal propulsion while exhibiting internal red muscle without associated retia is unique to L. imperialis among all extant fishes, raising the macroevolutionary question of whether this species - in geologic timescales - will remain an ectotherm or evolve red muscle endothermy.
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Affiliation(s)
- Martin C Arostegui
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Michelle R Shero
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Lawrence R Frank
- Center for Scientific Computation in Imaging, University of California San Diego, La Jolla, CA, USA
| | - Rachel M Berquist
- Center for Scientific Computation in Imaging, University of California San Diego, La Jolla, CA, USA
| | - Camrin D Braun
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
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4
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Wilson LE. Rapid growth in Late Cretaceous sea turtles reveals life history strategies similar to extant leatherbacks. PeerJ 2023; 11:e14864. [PMID: 36793890 PMCID: PMC9924133 DOI: 10.7717/peerj.14864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/17/2023] [Indexed: 02/12/2023] Open
Abstract
Modern sea turtle long bone osteohistology has been surprisingly well-studied, as it is used to understand sea turtle growth and the timing of life history events, thus informing conservation decisions. Previous histologic studies reveal two distinct bone growth patterns in extant sea turtle taxa, with Dermochelys (leatherbacks) growing faster than the cheloniids (all other living sea turtles). Dermochelys also has a unique life history compared to other sea turtles (large size, elevated metabolism, broad biogeographic distribution, etc.) that is likely linked to bone growth strategies. Despite the abundance of data on modern sea turtle bone growth, extinct sea turtle osteohistology is virtually unstudied. Here, long bone microstructure of the large, Cretaceous sea turtle Protostega gigas is examined to better understand its life history. Humeral and femoral analysis reveals bone microstructure patterns similar to Dermochelys with variable but sustained rapid growth through early ontogeny. Similarities between Progostegea and Dermochelys osteohistology suggest similar life history strategies like elevated metabolic rates with rapid growth to large body size and sexual maturity. Comparison to the more basal protostegid Desmatochelys indicates elevated growth rates are not present throughout the entire Protostegidae, but evolved in larger and more derived taxa, possibly in response to Late Cretaceous ecological changes. Given the uncertainties in the phylogenetic placement of the Protostegidae, these results either support convergent evolution towards rapid growth and elevated metabolism in both derived protostegids and dermochelyids, or a close evolutionary relationship between the two taxa. Better understanding the evolution and diversity of sea turtle life history strategies during the Late Cretaceous greenhouse climate can also impact current sea turtle conservation decisions.
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5
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Krahl A, Werneburg I. Deep-time invention and hydrodynamic convergences through amniote flipper evolution. Anat Rec (Hoboken) 2022; 306:1323-1355. [PMID: 36458511 DOI: 10.1002/ar.25119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/15/2022] [Accepted: 10/25/2022] [Indexed: 12/04/2022]
Abstract
The diapsid plesiosaurs were pelagic and inhabited the oceans from the Triassic to the Cretaceous. A key evolutionary character of plesiosaurs is the four wing-like flippers. While it is mostly accepted that plesiosaurs were underwater fliers like marine turtles, penguins, and maybe whales, other swimming styles have been suggested in the past. These are rowing and a combination of rowing and underwater flight (e.g., pig-nosed turtle, sea lion). Underwater fliers use lift in contrast to rowers that employ drag. For efficiently profiting of lift during underwater flying, it is necessary that plesiosaurs twisted their flippers by muscular activity. To research the evolution of flipper twisting in plesiosaurs and functionally analogous taxa, including turtles, we used anatomical network analysis (AnNA) and reassessed distal flipper muscle functions. We coded bone-to-bone and additionally muscle-to-bone contacts in N × N matrices for foreflippers of the plesiosaur, the loggerhead sea turtle, the pig-nosed turtle, the African penguin, the California sea lion, and the humpback whale based on literature data. In "R," "igraph" was run by using a walktrap algorithm to obtain morphofunctional modules. AnNA revealed that muscle-to-bone contacts are needed to detect contributions of modules to flipper motions, whereas only-bone matrices are not informative for that. Furthermore, the plesiosaur, the marine turtles, the seal, and the penguin flipper twisting mechanisms, but the penguin cannot actively twist the flipper trailing edge. Finally, the foreflipper of the pig-nosed turtle and of the whale is not actively twisted during swimming.
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Affiliation(s)
- Anna Krahl
- Paläontologische Sammlung, Fachbereich Geowissenschaften der Universität Tübingen, Tübingen, Germany
| | - Ingmar Werneburg
- Paläontologische Sammlung, Fachbereich Geowissenschaften der Universität Tübingen, Tübingen, Germany.,Senckenberg Center for Human Evolution and Palaeoenvironment an der Universität Tübingen, Tübingen, Germany
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6
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Effect of water temperature on the duration of the internesting interval across sea turtle species. J Therm Biol 2022; 110:103342. [DOI: 10.1016/j.jtherbio.2022.103342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/12/2022] [Accepted: 09/20/2022] [Indexed: 11/17/2022]
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7
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Arfuso F, Cerutti RD, Scaglione MC, Sciabarrasi A, Giannetto C, Piccione G. Evaluation of locomotor activity in female Chelonoidis chilensis (Testudinidae, Gray 1870) in response to artificial photoperiod and temperature treatments. AMPHIBIA-REPTILIA 2022. [DOI: 10.1163/15685381-bja10096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Turtles as many other reptiles are capable of orientating their bodies toward the sun. This conduct requires the presence of an internal biological chronometer in the organism that regulates this behavior. Thus, a description of the internal clock in these reptiles is of interest. The assessment of locomotor activity can be considered a reliable indicator of biological clock function. This study aimed to investigate the effect of different artificial photoperiod and ambient temperature schedules on total locomotor activity of female Chelonoidis chilensis and its rhythmicity. Six C. chilensis specimens were exposed to different artificial photoperiods and temperature regimes each fixed for seven days. It was observed that the activity period during the different experimental schedules was close to the 24 hours indicating a daily rhythmicity. Moreover, all tortoises showed a similar total locomotor activity pattern displaying the most of motion during light phase. Under the condition of constant light tortoises exhibited a self-sustaining rhythm not entrained to light and temperature zeitgebers, thus, suggesting its possible endogenous periodicity. Though this study deepens the knowledge on the rhythmic system of C. chilensis, further investigations are needed to achieve a more detailed understanding of tortoise biological clock.
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Affiliation(s)
- Francesca Arfuso
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168 Messina, Italy
| | - Raúl D. Cerutti
- Department of Veterinary Sciences, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Maria C. Scaglione
- Department of Veterinary Sciences, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Antonio Sciabarrasi
- Department of Veterinary Sciences, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Claudia Giannetto
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168 Messina, Italy
| | - Giuseppe Piccione
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168 Messina, Italy
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8
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Wiemann J, Menéndez I, Crawford JM, Fabbri M, Gauthier JA, Hull PM, Norell MA, Briggs DEG. Fossil biomolecules reveal an avian metabolism in the ancestral dinosaur. Nature 2022; 606:522-526. [PMID: 35614213 DOI: 10.1038/s41586-022-04770-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 04/19/2022] [Indexed: 11/09/2022]
Abstract
Birds and mammals independently evolved the highest metabolic rates among living animals1. Their metabolism generates heat that enables active thermoregulation1, shaping the ecological niches they can occupy and their adaptability to environmental change2. The metabolic performance of birds, which exceeds that of mammals, is thought to have evolved along their stem lineage3-10. However, there is no proxy that enables the direct reconstruction of metabolic rates from fossils. Here we use in situ Raman and Fourier-transform infrared spectroscopy to quantify the in vivo accumulation of metabolic lipoxidation signals in modern and fossil amniote bones. We observe no correlation between atmospheric oxygen concentrations11 and metabolic rates. Inferred ancestral states reveal that the metabolic rates consistent with endothermy evolved independently in mammals and plesiosaurs, and are ancestral to ornithodirans, with increasing rates along the avian lineage. High metabolic rates were acquired in pterosaurs, ornithischians, sauropods and theropods well before the advent of energetically costly adaptations, such as flight in birds. Although they had higher metabolic rates ancestrally, ornithischians reduced their metabolic abilities towards ectothermy. The physiological activities of such ectotherms were dependent on environmental and behavioural thermoregulation12, in contrast to the active lifestyles of endotherms1. Giant sauropods and theropods were not gigantothermic9,10, but true endotherms. Endothermy in many Late Cretaceous taxa, in addition to crown mammals and birds, suggests that attributes other than metabolism determined their fate during the terminal Cretaceous mass extinction.
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Affiliation(s)
- Jasmina Wiemann
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA.
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
- Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA.
| | - Iris Menéndez
- Departamento de Geodinámica, Estratigrafía y Paleontología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, Madrid, Spain
- Departamento de Cambio Medioambiental, Instituto de Geociencias (UCM, CSIC), Madrid, Spain
| | | | - Matteo Fabbri
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
| | - Jacques A Gauthier
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
| | - Pincelli M Hull
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
| | - Mark A Norell
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Derek E G Briggs
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Yale Peabody Museum of Natural History, Yale University, New Haven, CT, USA
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9
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Hatch JM, Haas HL, Sasso CR, Patel SH, Smolowitz RJ. Estimating the complex patterns of survey availability for loggerhead turtles. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Joshua M. Hatch
- NOAA National Marine Fisheries Service, NEFSC Woods Hole 02543 MA USA
| | - Heather L. Haas
- NOAA National Marine Fisheries Service, NEFSC Woods Hole 02543 MA USA
| | | | - Samir H. Patel
- Coonamessett Farm Foundation, 277 Hatchville Road East Falmouth 02536 MA USA
| | - Ronald J. Smolowitz
- Coonamessett Farm Foundation, 277 Hatchville Road East Falmouth 02536 MA USA
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10
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Jensen B, Lauridsen H, Webb GJW, Wang T. Anatomy of the heart of the leatherback turtle. J Anat 2022; 241:535-544. [PMID: 35412658 PMCID: PMC9296022 DOI: 10.1111/joa.13670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/31/2022] [Accepted: 03/31/2022] [Indexed: 11/27/2022] Open
Abstract
Non‐crocodylian reptiles have hearts with a single ventricle, which is partially separated by a muscular ridge that provides some separation of blood flows. An exceptional situation exists in monitor lizards and pythons, where the ventricular left side generates a much higher systolic blood pressure than the right side, thus resembling mammals and birds. This functional division of the ventricle depends on a large muscular ridge and may relate to high metabolic demand. The large leatherback turtle (<1000 kg), with its extensive migrations and elevated body temperatures, may have similar adaptations. We report on the anatomy of the hearts of two leatherback turtles. One stranded in Ballum, Denmark in 2020, and was examined in detail, supplemented by observations and photos of an additional stranding specimen from Canada. The external morphology of the leatherback heart resembles that of other turtles, but it is large. We made morphometric measurements of the Ballum heart and created an interactive 3D model using high‐resolution MRI. The volume of the ventricle was 950 ml, from a turtle of 300 kg, which is proportionally almost twice as large as in other reptiles. The Ballum heart was compared to MRI scans of the hearts of a tortoise, a python, and a monitor lizard. Internally, the leatherback heart is typical of non‐crocodylian reptiles and did not contain the well‐developed septation found in pythons and monitor lizards. We conclude that if leatherback turtles have exceptional circulation needs, they are sustained with a relatively large but otherwise typical non‐crocodylian reptile heart.
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Affiliation(s)
- Bjarke Jensen
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centres, Amsterdam, The Netherlands
| | - Henrik Lauridsen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Grahame J W Webb
- Wildlife Management International, Karama, Australia.,Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia
| | - Tobias Wang
- Department of Biology-Zoophysiology, Aarhus University, Aarhus, Denmark
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11
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Morphometrics and blood analytes of leatherback sea turtle hatchlings (Dermochelys coriacea) from Florida: reference intervals, temporal trends with clutch deposition date, and body size correlations. J Comp Physiol B 2022; 192:313-324. [PMID: 34997274 DOI: 10.1007/s00360-021-01422-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/12/2021] [Accepted: 11/22/2021] [Indexed: 10/19/2022]
Abstract
The northwest Atlantic leatherback sea turtle (Dermochelys coriacea) population is exhibiting decreasing trends along numerous nesting beaches. Since population health and viability are inherently linked, it is important to establish species- and life-stage class-specific blood analyte reference intervals (RIs) so that effects of future disturbances on organismal health can be better understood. For hatchling leatherbacks, the objectives of this study were to (1) establish RIs for morphometrics and blood analytes; (2) evaluate correlations between hatchling morphometrics, blood analytes, and hatching success; and (3) determine temporal trends in hatchling morphometrics and blood analytes across nesting season. Blood samples were collected from 176 naturally emerging leatherback hatchlings from 18 clutches. Reference intervals were established for morphometrics and blood analytes. Negative relationships were noted between hatchling mass and packed cell volume, total white blood cells, heterophils, lymphocytes, and total protein and between body condition index (BCI) and immature red blood cells (RBC), RBC polychromasia and anisocytosis, and total protein. Clutch deposition date showed positive relationships with lymphocytes and total protein, and negative relationships with hatchling mass and BCI. Hatching success was positively correlated with mass, and negatively with total protein and glucose, suggesting that nutritional provisions in eggs, incubation time, and/or metabolic rates could change later in the season and affect survivorship. These various observed correlations provide evidence for increased physiological stress (e.g., inflammation, subclinical dehydration) in hatchlings emerging later in nesting season, presumably due to increased nest temperatures or other environmental factors (e.g., moisture/rainfall). Data reported herein provide morphometric and blood analyte data for leatherback hatchlings and will allow for future investigations into spatiotemporal trends and responses to various stressors.
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12
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Braun CD, Arostegui MC, Thorrold SR, Papastamatiou YP, Gaube P, Fontes J, Afonso P. The Functional and Ecological Significance of Deep Diving by Large Marine Predators. ANNUAL REVIEW OF MARINE SCIENCE 2022; 14:129-159. [PMID: 34416123 DOI: 10.1146/annurev-marine-032521-103517] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Many large marine predators make excursions from surface waters to the deep ocean below 200 m. Moreover, the ability to access meso- and bathypelagic habitats has evolved independently across marine mammals, reptiles, birds, teleost fishes, and elasmobranchs. Theoretical and empirical evidence suggests a number of plausible functional hypotheses for deep-diving behavior. Developing ways to test among these hypotheses will, however, require new ways to quantify animal behavior and biophysical oceanographic processes at coherent spatiotemporal scales. Current knowledge gaps include quantifying ecological links between surface waters and mesopelagic habitats and the value of ecosystem services provided by biomass in the ocean twilight zone. Growing pressure for ocean twilight zone fisheries creates an urgent need to understand the importance of the deep pelagic ocean to large marine predators.
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Affiliation(s)
- Camrin D Braun
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA;
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Martin C Arostegui
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA;
- Air-Sea Interaction and Remote Sensing Department, Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA
| | - Simon R Thorrold
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA;
| | - Yannis P Papastamatiou
- Institute of Environment, Department of Biological Sciences, Florida International University, Miami, Florida 33181, USA
| | - Peter Gaube
- Air-Sea Interaction and Remote Sensing Department, Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA
| | - Jorge Fontes
- Okeanos and Institute of Marine Research, University of the Azores, 9901-862 Horta, Portugal
| | - Pedro Afonso
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA;
- Okeanos and Institute of Marine Research, University of the Azores, 9901-862 Horta, Portugal
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13
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Robinson NJ, García-Párraga D, Stacy BA, Costidis AM, Blanco GS, Clyde-Brockway CE, Haas HL, Harms CA, Patel SH, Stacy NI, Fahlman A. A Baseline Model For Estimating the Risk of Gas Embolism in Sea Turtles During Routine Dives. Front Physiol 2021; 12:678555. [PMID: 34539425 PMCID: PMC8440993 DOI: 10.3389/fphys.2021.678555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
Sea turtles, like other air-breathing diving vertebrates, commonly experience significant gas embolism (GE) when incidentally caught at depth in fishing gear and brought to the surface. To better understand why sea turtles develop GE, we built a mathematical model to estimate partial pressures of N2 (PN2), O2 (PO2), and CO2 (PCO2) in the major body-compartments of diving loggerheads (Caretta caretta), leatherbacks (Dermochelys coriacea), and green turtles (Chelonia mydas). This model was adapted from a published model for estimating gas dynamics in marine mammals and penguins. To parameterize the sea turtle model, we used values gleaned from previously published literature and 22 necropsies. Next, we applied this model to data collected from free-roaming individuals of the three study species. Finally, we varied body-condition and cardiac output within the model to see how these factors affected the risk of GE. Our model suggests that cardiac output likely plays a significant role in the modulation of GE, especially in the deeper diving leatherback turtles. This baseline model also indicates that even during routine diving behavior, sea turtles are at high risk of GE. This likely means that turtles have additional behavioral, anatomical, and/or physiologic adaptions that serve to reduce the probability of GE but were not incorporated in this model. Identifying these adaptations and incorporating them into future iterations of this model will further reveal the factors driving GE in sea turtles.
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Affiliation(s)
- Nathan J. Robinson
- Department of Research, Fundación Oceanogràfic de la Comunidad Valenciana, Valencia, Spain
| | - Daniel García-Párraga
- Department of Research, Fundación Oceanogràfic de la Comunidad Valenciana, Valencia, Spain
| | - Brian A. Stacy
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Protected Resources, University of Florida (duty station), Washington, DC, United States
| | | | - Gabriela S. Blanco
- Instituto de Biología de Organismos Marinos (IBIOMAR-CCT CONICET-CENPAT), Puerto Madryn, Argentina
| | | | - Heather L. Haas
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA, United States
| | - Craig A. Harms
- Department of Clinical Sciences and Center for Marine Sciences and Technology, North Carolina State University, Raleigh, NC, United States
| | - Samir H. Patel
- Coonamessett Farm Foundation, East Falmouth, MA, United States
| | - Nicole I. Stacy
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States
| | - Andreas Fahlman
- Department of Research, Fundación Oceanogràfic de la Comunidad Valenciana, Valencia, Spain
- Global Diving Research, Inc., Ottawa, ON, Canada
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14
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Watanabe YY, Goldbogen JA. Too big to study? The biologging approach to understanding the behavioural energetics of ocean giants. J Exp Biol 2021; 224:270831. [PMID: 34232316 DOI: 10.1242/jeb.202747] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Wild animals are under selective pressure to optimise energy budgets; therefore, quantifying energy expenditure, intake and allocation to specific activities is important if we are to understand how animals survive in their environment. One approach toward estimating energy budgets has involved measuring oxygen consumption rates under controlled conditions and constructing allometric relationships across species. However, studying 'giant' marine vertebrates (e.g. pelagic sharks, whales) in this way is logistically difficult or impossible. An alternative approach involves the use of increasingly sophisticated electronic tags that have allowed recordings of behaviour, internal states and the surrounding environment of marine animals. This Review outlines how we could study the energy expenditure and intake of free-living ocean giants using this 'biologging' technology. There are kinematic, physiological and theoretical approaches for estimating energy expenditure, each of which has merits and limitations. Importantly, tag-derived energy proxies can hardly be validated against oxygen consumption rates for giant species. The proxies are thus qualitative, rather than quantitative, estimates of energy expenditure, and have more limited utilities. Despite this limitation, these proxies allow us to study the energetics of ocean giants in their behavioural context, providing insight into how these animals optimise their energy budgets under natural conditions. We also outline how information on energy intake and foraging behaviour can be gained from tag data. These methods are becoming increasingly important owing to the natural and anthropogenic environmental changes faced by ocean giants that can alter their energy budgets, fitness and, ultimately, population sizes.
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Affiliation(s)
- Yuuki Y Watanabe
- National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan.,Department of Polar Science, The Graduate University for Advanced Studies, SOKENDAI, Tachikawa, Tokyo 190-8518, Japan
| | - Jeremy A Goldbogen
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA
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15
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Williams CL, Hindle AG. Field Physiology: Studying Organismal Function in the Natural Environment. Compr Physiol 2021; 11:1979-2015. [PMID: 34190338 DOI: 10.1002/cphy.c200005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Continuous physiological measurements collected in field settings are essential to understand baseline, free-ranging physiology, physiological range and variability, and the physiological responses of organisms to disturbances. This article presents a current summary of the available technologies to continuously measure the direct physiological parameters in the field at high-resolution/instantaneous timescales from freely behaving animals. There is a particular focus on advantages versus disadvantages of available methods as well as emerging technologies "on the horizon" that may have been validated in captive or laboratory-based scenarios but have yet to be applied in the wild. Systems to record physiological variables from free-ranging animals are reviewed, including radio (VHF/UFH) telemetry, acoustic telemetry, and dataloggers. Physiological parameters that have been continuously measured in the field are addressed in seven sections including heart rate and electrocardiography (ECG); electromyography (EMG); electroencephalography (EEG); body temperature; respiratory, blood, and muscle oxygen; gastric pH and motility; and blood pressure and flow. The primary focal sections are heart rate and temperature as these can be, and have been, extensively studied in free-ranging organisms. Predicted aspects of future innovation in physiological monitoring are also discussed. The article concludes with an overview of best practices and points to consider regarding experimental designs, cautions, and effects on animals. © 2021 American Physiological Society. Compr Physiol 11:1979-2015, 2021.
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Affiliation(s)
- Cassondra L Williams
- National Marine Mammal Foundation, San Diego, California, USA.,Department of Ecology and Evolutionary Biology, School of Biological Science, University of California Irvine, Irvine, California, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
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16
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Okuyama J, Benson SR, Dutton PH, Seminoff JA. Changes in dive patterns of leatherback turtles with sea surface temperature and potential foraging habitats. Ecosphere 2021. [DOI: 10.1002/ecs2.3365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Junichi Okuyama
- Marine Mammal and Turtle Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California92037USA
| | - Scott R. Benson
- Marine Mammal and Turtle Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Moss Landing California95039USA
- Moss Landing Marine Laboratories Moss Landing California95039USA
| | - Peter H. Dutton
- Marine Mammal and Turtle Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California92037USA
| | - Jeffrey A. Seminoff
- Marine Mammal and Turtle Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California92037USA
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17
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Cox CL, Tribble HO, Richardson S, Chung AK, Curlis JD, Logan ML. Thermal ecology and physiology of an elongate and semi-fossorial arthropod, the bark centipede. J Therm Biol 2020; 94:102755. [DOI: 10.1016/j.jtherbio.2020.102755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 09/11/2020] [Accepted: 10/04/2020] [Indexed: 02/08/2023]
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18
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Kahane-Rapport SR, Savoca MS, Cade DE, Segre PS, Bierlich KC, Calambokidis J, Dale J, Fahlbusch JA, Friedlaender AS, Johnston DW, Werth AJ, Goldbogen JA. Lunge filter feeding biomechanics constrain rorqual foraging ecology across scale. J Exp Biol 2020; 223:jeb224196. [PMID: 32820028 DOI: 10.1242/jeb.224196] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 08/13/2020] [Indexed: 10/23/2022]
Abstract
Fundamental scaling relationships influence the physiology of vital rates, which in turn shape the ecology and evolution of organisms. For diving mammals, benefits conferred by large body size include reduced transport costs and enhanced breath-holding capacity, thereby increasing overall foraging efficiency. Rorqual whales feed by engulfing a large mass of prey-laden water at high speed and filtering it through baleen plates. However, as engulfment capacity increases with body length (engulfment volume∝body length3.57), the surface area of the baleen filter does not increase proportionally (baleen area∝body length1.82), and thus the filtration time of larger rorquals predictably increases as the baleen surface area must filter a disproportionally large amount of water. We predicted that filtration time should scale with body length to the power of 1.75 (filter time∝body length1.75). We tested this hypothesis on four rorqual species using multi-sensor tags with corresponding unoccupied aircraft systems-based body length estimates. We found that filter time scales with body length to the power of 1.79 (95% CI: 1.61-1.97). This result highlights a scale-dependent trade-off between engulfment capacity and baleen area that creates a biomechanical constraint to foraging through increased filtration time. Consequently, larger whales must target high-density prey patches commensurate to the gulp size to meet their increased energetic demands. If these optimal patches are absent, larger rorquals may experience reduced foraging efficiency compared with smaller whales if they do not match their engulfment capacity to the size of targeted prey aggregations.
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Affiliation(s)
- S R Kahane-Rapport
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - M S Savoca
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - D E Cade
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
- Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - P S Segre
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - K C Bierlich
- Nicholas School of the Environment, Duke University Marine Laboratory, Beaufort, NC 27710, USA
| | - J Calambokidis
- Cascadia Research Collective, 218 W. 4th Ave., Olympia, WA 98501, USA
| | - J Dale
- Nicholas School of the Environment, Duke University Marine Laboratory, Beaufort, NC 27710, USA
| | - J A Fahlbusch
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - A S Friedlaender
- Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - D W Johnston
- Nicholas School of the Environment, Duke University Marine Laboratory, Beaufort, NC 27710, USA
| | - A J Werth
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA
| | - J A Goldbogen
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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19
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Favilla AB, Costa DP. Thermoregulatory Strategies of Diving Air-Breathing Marine Vertebrates: A Review. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.555509] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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20
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Burns TJ, Thomson RR, McLaren RA, Rawlinson J, McMillan E, Davidson H, Kennedy MW. Buried treasure-marine turtles do not 'disguise' or 'camouflage' their nests but avoid them and create a decoy trail. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200327. [PMID: 32537227 PMCID: PMC7277256 DOI: 10.1098/rsos.200327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/06/2020] [Indexed: 06/11/2023]
Abstract
After laying their eggs and refilling the egg chamber, sea turtles scatter sand extensively around the nest site. This is presumed to camouflage the nest, or optimize local conditions for egg development, but a consensus on its function is lacking. We quantified activity and mapped the movements of hawksbill (Eretmochelys imbricata) and leatherback (Dermochelys coriacea) turtles during sand-scattering. For leatherbacks, we also recorded activity at each sand-scattering position. For hawksbills, we recorded breathing rates during nesting as an indicator of metabolic investment and compared with published values for leatherbacks. Temporal and inferred metabolic investment in sand-scattering was substantial for both species. Neither species remained near the nest while sand-scattering, instead moving to several other positions to scatter sand, changing direction each time, progressively displacing themselves from the nest site. Movement patterns were highly diverse between individuals, but activity at each sand-scattering position changed little between completion of egg chamber refilling and return to the sea. Our findings are inconsistent with sand-scattering being to directly camouflage the nest, or primarily for modifying the nest-proximal environment. Instead, they are consistent with the construction of a series of dispersed decoy nests that may reduce the discovery of nests by predators.
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21
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Pimiento C, Leprieur F, Silvestro D, Lefcheck JS, Albouy C, Rasher DB, Davis M, Svenning JC, Griffin JN. Functional diversity of marine megafauna in the Anthropocene. SCIENCE ADVANCES 2020; 6:eaay7650. [PMID: 32494601 PMCID: PMC7164949 DOI: 10.1126/sciadv.aay7650] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 01/13/2020] [Indexed: 05/10/2023]
Abstract
Marine megafauna, the largest animals in the oceans, serve key roles in ecosystem functioning. Yet, one-third of these animals are at risk of extinction. To better understand the potential consequences of megafaunal loss, here we quantify their current functional diversity, predict future changes under different extinction scenarios, and introduce a new metric [functionally unique, specialized and endangered (FUSE)] that identifies threatened species of particular importance for functional diversity. Simulated extinction scenarios forecast marked declines in functional richness if current trajectories are maintained during the next century (11% globally; up to 24% regionally), with more marked reductions (48% globally; up to 70% at the poles) beyond random expectations if all threatened species eventually go extinct. Among the megafaunal groups, sharks will incur a disproportionate loss of functional richness. We identify top FUSE species and suggest a renewed focus on these species to preserve the ecosystem functions provided by marine megafauna.
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Affiliation(s)
- C. Pimiento
- Department of Biosciences, Swansea University, Wallace Building, Singleton Park, Swansea SA2 8PP, UK
- Smithsonian Tropical Research Institute, Box 2072, Balboa, Panama
- Corresponding author.
| | - F. Leprieur
- MARBEC, Université de Montpellier, CNRS, Ifremer, IRD, Montpellier, France
- Institut Universitaire de France (IUF), Paris, France
| | - D. Silvestro
- Department of Biological and Environmental Sciences, University of Gothenburg and Global Gothenburg Biodiversity Centre, 41319 Gothenburg, Sweden
- Department of Computational Biology, University of Lausanne, Lausanne 1015, Switzerland
| | - J. S. Lefcheck
- Tennenbaum Marine Observatories Network, MarineGEO, Smithsonian Environmental Research Center, Edgewater, MD 21037, USA
| | - C. Albouy
- IFREMER, Unité Ecologie et Modèles pour l’Halieutique, Nantes Cedex 3, France
| | - D. B. Rasher
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, ME 04544, USA
| | - M. Davis
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE) and Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
- Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, CA 90007, USA
| | - J.-C. Svenning
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE) and Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - J. N. Griffin
- Department of Biosciences, Swansea University, Wallace Building, Singleton Park, Swansea SA2 8PP, UK
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22
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Dawson RR, Field DJ, Hull PM, Zelenitsky DK, Therrien F, Affek HP. Eggshell geochemistry reveals ancestral metabolic thermoregulation in Dinosauria. SCIENCE ADVANCES 2020; 6:eaax9361. [PMID: 32110726 PMCID: PMC7021498 DOI: 10.1126/sciadv.aax9361] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Studying the origin of avian thermoregulation is complicated by a lack of reliable methods for measuring body temperatures in extinct dinosaurs. Evidence from bone histology and stableisotopes often relies on uncertain assumptions about the relationship between growth rate and body temperature, or the isotopic composition (δ18O) of body water. Clumped isotope (Δ47) paleothermometry, based on binding of 13C to 18O, provides a more robust tool, but has yet to be applied across a broad phylogenetic range of dinosaurs while accounting for paleoenvironmental conditions. Applying this method to well-preserved fossil eggshells demonstrates that the three major clades of dinosaurs, Ornithischia, Sauropodomorpha, and Theropoda, were characterized by warm body temperatures. Dwarf titanosaurs may have exhibited similar body temperatures to larger sauropods, although this conclusion isprovisional, given current uncertainties in taxonomic assignment of dwarf titanosaur eggshell. Our results nevertheless reveal that metabolically controlled thermoregulation was the ancestral condition for Dinosauria.
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Affiliation(s)
- Robin R. Dawson
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - Daniel J. Field
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
| | - Pincelli M. Hull
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - Darla K. Zelenitsky
- Department of Geoscience, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - François Therrien
- Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta T0J 0Y0, Canada
| | - Hagit P. Affek
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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23
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Legendre LJ, Davesne D. The evolution of mechanisms involved in vertebrate endothermy. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190136. [PMID: 31928191 DOI: 10.1098/rstb.2019.0136] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Endothermy, i.e. the endogenous production of metabolic heat, has evolved multiple times among vertebrates, and several strategies of heat production have been studied extensively by physiologists over the course of the twentieth century. The independent acquisition of endothermy by mammals and birds has been the subject of many hypotheses regarding their origin and associated evolutionary constraints. Many groups of vertebrates, however, are thought to possess other mechanisms of heat production, and alternative ways to regulate thermogenesis that are not always considered in the palaeontological literature. Here, we perform a review of the mechanisms involved in heat production, with a focus on cellular and molecular mechanisms, in a phylogenetic context encompassing the entire vertebrate diversity. We show that endothermy in mammals and birds is not as well defined as commonly assumed by evolutionary biologists and consists of a vast array of physiological strategies, many of which are currently unknown. We also describe strategies found in other vertebrates, which may not always be considered endothermy, but nonetheless correspond to a process of active thermogenesis. We conclude that endothermy is a highly plastic character in vertebrates and provides a guideline on terminology and occurrences of the different types of heat production in vertebrate evolution. This article is part of the theme issue 'Vertebrate palaeophysiology'.
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Affiliation(s)
- Lucas J Legendre
- Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA
| | - Donald Davesne
- Department of Earth Sciences, University of Oxford, Oxford, UK
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24
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Rezende EL, Bacigalupe LD, Nespolo RF, Bozinovic F. Shrinking dinosaurs and the evolution of endothermy in birds. SCIENCE ADVANCES 2020; 6:eaaw4486. [PMID: 31911937 PMCID: PMC6938711 DOI: 10.1126/sciadv.aaw4486] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 11/04/2019] [Indexed: 05/30/2023]
Abstract
The evolution of endothermy represents a major transition in vertebrate history, yet how and why endothermy evolved in birds and mammals remains controversial. Here, we combine a heat transfer model with theropod body size data to reconstruct the evolution of metabolic rates along the bird stem lineage. Results suggest that a reduction in size constitutes the path of least resistance for endothermy to evolve, maximizing thermal niche expansion while obviating the costs of elevated energy requirements. In this scenario, metabolism would have increased with the miniaturization observed in the Early-Middle Jurassic (~180 to 170 million years ago), resulting in a gradient of metabolic levels in the theropod phylogeny. Whereas basal theropods would exhibit lower metabolic rates, more recent nonavian lineages were likely decent thermoregulators with elevated metabolism. These analyses provide a tentative temporal sequence of the key evolutionary transitions that resulted in the emergence of small, endothermic, feathered flying dinosaurs.
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Affiliation(s)
- Enrico L. Rezende
- Center of Applied Ecology and Sustainability (CAPES), Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 6513677, Chile
| | - Leonardo D. Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja, Valdivia 5090000, Chile
| | - Roberto F. Nespolo
- Center of Applied Ecology and Sustainability (CAPES), Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 6513677, Chile
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja, Valdivia 5090000, Chile
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Francisco Bozinovic
- Center of Applied Ecology and Sustainability (CAPES), Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 6513677, Chile
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25
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Nakamura I, Matsumoto R, Sato K. Body temperature stability observed in the whale sharks, the world's largest fish. J Exp Biol 2020:jeb.210286. [PMID: 34005620 DOI: 10.1242/jeb.210286] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 04/20/2020] [Indexed: 02/24/2024]
Abstract
It is generally assumed that the body temperature of large animals is less likely to change due to their large body size, resulting in a high thermal inertia and a smaller surface area to volume ratio. The goal of this study was to investigate the stability of body temperature in large fish using data from field experiments. We measured the muscle temperatures of free-ranging whale sharks (Rhincodon typus), the largest extant fish globally, and investigated their ectothermic physiology and the stability of their body temperatures. The measured muscle temperature of the whale sharks changed substantially more slowly than the water temperature fluctuations associated with vertical movements, and the whole-body heat-transfer coefficients (HTC) of whale sharks estimated using heat-budget models were lower than those of any other fish species measured to date. The heat-budget models also showed that internal heat production does not contribute to changes in muscle temperature. A comparative analysis showed that the HTC at cooling in various fish species including both ectothermic and endothermic species ranging from 10-4 to 103 kg was proportional to body mass-0.63. This allometry was present regardless of whether the fish were ectothermic or endothermic, and was an extension of the relationship observed in previous studies on small fish. Thus, large fish have the advantage of body temperature stability while moving in environments with large temperature variations. Our results suggest that the large body size of whale sharks aids in preventing a decrease in body temperature during deep excursions to more than 1000 m depths without high metabolic costs of producing heat.
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Affiliation(s)
- Itsumi Nakamura
- Institute for East China Sea Research, Nagasaki University, 1551-7 Tairamachi, Nagasaki, Nagasaki 851-2213, Japan
| | - Rui Matsumoto
- Okinawa Churaumi Aquarium, 424 Ishikawa, Motobucho, Kunigamigun, Okinawa 905-0206, Japan
| | - Katsufumi Sato
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
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26
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Soslau G. The role of the red blood cell and platelet in the evolution of mammalian and avian endothermy. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 334:113-127. [DOI: 10.1002/jez.b.22922] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 10/04/2019] [Accepted: 11/09/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Gerald Soslau
- Department of Biochemistry and Molecular BiologyDrexel University College of MedicinePhiladelphia Pennsylvania
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27
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Reid BN, Naro-Maciel E, Hahn AT, FitzSimmons NN, Gehara M. Geography best explains global patterns of genetic diversity and postglacial co-expansion in marine turtles. Mol Ecol 2019; 28:3358-3370. [PMID: 31264298 DOI: 10.1111/mec.15165] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/31/2019] [Accepted: 06/07/2019] [Indexed: 01/07/2023]
Abstract
For many species, climate oscillations drove cycles of population contraction during cool glacial periods followed by expansion during interglacials. Some groups, however, show evidence of uniform and synchronous expansion, while others display differences in the timing and extent of demographic change. We compared demographic histories inferred from genetic data across marine turtle species to identify responses to postglacial warming shared across taxa and to examine drivers of past demographic change at the global scale. Using coalescent simulations and approximate Bayesian computation (ABC), we estimated demographic parameters, including the likelihood of past population expansion, from a mitochondrial data set encompassing 23 previously identified lineages from all seven marine turtle species. For lineages with a high posterior probability of expansion, we conducted a hierarchical ABC analysis to estimate the proportion of lineages expanding synchronously and the timing of synchronous expansion. We used Bayesian model averaging to identify variables associated with expansion and genetic diversity. Approximately 60% of extant marine turtle lineages showed evidence of expansion, with the rest mainly exhibiting patterns of genetic diversity most consistent with population stability. For lineages showing expansion, there was a strong signal of synchronous expansion after the Last Glacial Maximum. Expansion and genetic diversity were best explained by ocean basin and the degree of endemism for a given lineage. Geographic differences in sensitivity to climate change have implications for prioritizing conservation actions in marine turtles as well as for identifying areas of past demographic stability and potential resilience to future climate change for broadly distributed taxa.
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Affiliation(s)
- Brendan N Reid
- W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, USA
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28
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Lalire M, Gaspar P. Modeling the active dispersal of juvenile leatherback turtles in the North Atlantic Ocean. MOVEMENT ECOLOGY 2019; 7:7. [PMID: 30858978 PMCID: PMC6394021 DOI: 10.1186/s40462-019-0149-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/24/2019] [Indexed: 05/27/2023]
Abstract
BACKGROUND The Northwest Atlantic (NWA) leatherback turtle (Dermochelys coriacea) subpopulation is one of the last healthy ones on Earth. Its conservation is thus of major importance for the conservation of the species itself. While adults are relatively well monitored, pelagic juveniles remain largely unobserved. In an attempt to reduce this knowledge gap, this paper presents the first detailed simulation of the open ocean dispersal of juveniles born on the main nesting beaches of French Guiana and Suriname (FGS). METHODS Dispersal is simulated using STAMM, an Individual Based Model in which juveniles actively disperse under the combined effects of oceanic currents and habitat-driven movements. For comparison purposes, passive dispersal under the sole effect of oceanic currents is also simulated. RESULTS Simulation results show that oceanic currents lead juveniles to cross the Atlantic at mid-latitudes. Unlike passive individuals, active juveniles undertake important north-south seasonal migrations while crossing the North Atlantic. They finally reach the European or North African coast and enter the Mediterranean Sea. Less than 4-year-old active turtles first arrive off Mauritania. Other productive areas on the eastern side of the Atlantic (the coast of Galicia and Portugal, the Gulf of Cadiz, the Bay of Biscay) and in the Mediterranean Sea are first reached by 6 to 9-year-old individuals. This active dispersal scheme, and its timing, appear to be consistent with all available stranding and bycatch data gathered on the Atlantic and Mediterranean coasts of Europe and North Africa. Simulation results also suggest that the timing of the dispersal and the quality of the habitats encountered by juveniles can, at least partly, explain why the NWA leatherback subpopulation is doing much better than the West Pacific one. CONCLUSION This paper provides the first detailed simulation of the spatial and temporal distribution of juvenile leatherback turtles dispersing from their FGS nesting beaches into the North Atlantic Ocean and Mediterranean Sea. Simulation results, corroborated by stranding and bycatch data, pinpoint several important developmental areas on the eastern side of the Atlantic Ocean and in the Mediterranean Sea. These results shall help focus observation and conservation efforts in these critical areas.
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Affiliation(s)
- Maxime Lalire
- Sustainable Management of Marine Ressources, Collecte Localisation Satellites, Ramonville Saint-Agne, France
| | - Philippe Gaspar
- Sustainable Management of Marine Ressources, Collecte Localisation Satellites, Ramonville Saint-Agne, France
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Watanabe YY, Payne NL, Semmens JM, Fox A, Huveneers C. Swimming strategies and energetics of endothermic white sharks during foraging. J Exp Biol 2019; 222:222/4/jeb185603. [DOI: 10.1242/jeb.185603] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 01/04/2019] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Some fishes and sea turtles are distinct from ectotherms by having elevated core body temperatures and metabolic rates. Quantifying the energetics and activity of the regionally endothermic species will help us understand how a fundamental biophysical process (i.e. temperature-dependent metabolism) shapes animal ecology; however, such information is limited owing to difficulties in studying these large, highly active animals. White sharks, Carcharodon carcharias, are the largest fish with regional endothermy, and potentially among the most energy-demanding fishes. Here, we deployed multi-sensor loggers on eight white sharks aggregating near colonies of long-nosed fur seals, Arctocephalus forsteri, off the Neptune Islands, Australia. Simultaneous measurements of depth, swim speed (a proxy for swimming metabolic rate) and body acceleration (indicating when sharks exhibited energy-efficient gliding behaviour) revealed their fine-scale swimming behaviour and allowed us to estimate their energy expenditure. Sharks repeatedly dived (mean swimming depth, 29 m) and swam at the surface between deep dives (maximum depth, 108 m). Modal swim speeds (0.80–1.35 m s−1) were slower than the estimated speeds that minimize cost of transport (1.3–1.9 m s−1), a pattern analogous to a ‘sit-and-wait’ strategy for a perpetually swimming species. All but one shark employed unpowered gliding during descents, rendering deep (>50 m) dives 29% less costly than surface swimming, which may incur additional wave drag. We suggest that these behavioural strategies may help sharks to maximize net energy gains by reducing swimming cost while increasing encounter rates with fast-swimming seals.
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Affiliation(s)
- Yuuki Y. Watanabe
- National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Tachikawa, Tokyo 190-8518, Japan
| | - Nicholas L. Payne
- University of Roehampton, Holybourne Avenue, London SW15 4JD, UK
- Trinity College Dublin, Dublin 2, Ireland
| | - Jayson M. Semmens
- Fisheries and Aquaculture Centre, Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 49, Hobart, Tasmania 7001, Australia
| | - Andrew Fox
- Fox Shark Research Foundation, Adelaide, South Australia 5070, Australia
| | - Charlie Huveneers
- College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
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30
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Vlachos E, Rabi M. Total evidence analysis and body size evolution of extant and extinct tortoises (Testudines: Cryptodira: Pan-Testudinidae). Cladistics 2018; 34:652-683. [PMID: 34706483 DOI: 10.1111/cla.12227] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2017] [Indexed: 01/18/2023] Open
Abstract
Testudinidae (tortoises) is an extant clade of terrestrial turtles of worldwide distribution and with a rich fossil record that provides an exceptional context for studying their evolutionary history. Because of the lack of global phylogenetic analyses integrating extinct taxa, our current knowledge of the relationships of the total clade of Testudinidae is rather poor. To resolve this issue, we performed the first total evidence analysis of Pan-Testudinidae. The total evidence trees are congruent with the molecular topology and agree on the dichotomy of derived Testudinidae (=Testudininae; Converted Clade Name) into two previously recognized major clades, Testudona and Geochelona (New Clade Name). The integration of extinct taxa into the analysis allowed the stratigraphic fit of the total evidence trees, indicating that crown Testudininae, Testudona and Geochelona all originated by the Late Eocene, in agreement with recent molecular estimates. Ghost lineage analysis indicates high diversification in the Late Eocene and in the Miocene. The age of crown Testudo is Late Miocene, again in accordance with some molecular dates. Phylogenetic placement of fossils demonstrates that giant body size independently evolved in multiple continental mainland taxa and confirms recent results deduced from living taxa-giantism in Testudinidae is not linked to the insular effect. An unexpected outcome is the recovery of miniaturization in Testudona (<30 cm carapace length) that emerged sometime between the Oligocene and Early Miocene. No clear correlation between body size evolution and climate is apparent, but increased taxon sampling may nevertheless demonstrate the role of cooling and warming as one of many influential variables.
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Affiliation(s)
- Evangelos Vlachos
- CONICET - Museo Paleontológico Egidio Feruglio, Av. Fontana 140, Trelew, Chubut, 9100, Argentina.,School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Márton Rabi
- Central Natural Science Collections, Martin-Luther University Halle-Wittenberg, Domplatz 4, 06108, Halle (Saale), Germany.,Department of Geosciences, University of Tübingen, Hölderlinstrasse 12, 72074, Tübingen, Germany
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31
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Wallace BP, Zolkewitz M, James MC. Discrete, high-latitude foraging areas are important to energy budgets and population dynamics of migratory leatherback turtles. Sci Rep 2018; 8:11017. [PMID: 30030495 PMCID: PMC6054646 DOI: 10.1038/s41598-018-29106-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 07/02/2018] [Indexed: 11/09/2022] Open
Abstract
Many broadly distributed migratory species exhibit fidelity to fine-scale areas that support vital life history requirements (e.g., resource acquisition, reproduction). Thus, such areas are critical for population dynamics and are of high conservation priority. Leatherback sea turtles are among the world's most widely distributed species, and their breeding and feeding areas are typically separated by thousands of kilometres. In this study, we analysed turtle-borne video data on daytime feeding rates and energy acquisition in Nova Scotia, Canada, to quantify the importance of this discrete, seasonal foraging area for leatherback energy requirements. Based on daytime foraging only, we estimate that a single foraging season in Nova Scotia could support 59% of a non-breeding leatherback's annual energy budget, and 29% of energetic requirements for a female on a typical 2-year reproductive cycle. However, maximum energy intake rates for leatherbacks are nearly four times lower than those of mammals and birds due the low energy content of leatherbacks' gelatinous zooplankton prey. These results illustrate that high quality, local-scale foraging areas such as Nova Scotia are critically important to the stability and future growth of the leatherback population in the Northwest Atlantic Ocean. Thus, as with other migratory species, efforts to reduce threats and maintain habitat quality in such areas should be high conservation priorities.
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Affiliation(s)
- Bryan P Wallace
- Conservation Science Partners, Inc., 5 Old Town Square, Suite 205, Fort Collins, CO, 80524, USA. .,Nicholas School of the Environment, Duke University, Beaufort, NC, USA.
| | | | - Michael C James
- Population Ecology Division, Fisheries and Oceans Canada, Dartmouth, Nova Scotia, B2Y 4A2, Canada
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32
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Fleischle CV, Wintrich T, Sander PM. Quantitative histological models suggest endothermy in plesiosaurs. PeerJ 2018; 6:e4955. [PMID: 29892509 PMCID: PMC5994164 DOI: 10.7717/peerj.4955] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/18/2018] [Indexed: 11/20/2022] Open
Abstract
Background Plesiosaurs are marine reptiles that arose in the Late Triassic and survived to the Late Cretaceous. They have a unique and uniform bauplan and are known for their very long neck and hydrofoil-like flippers. Plesiosaurs are among the most successful vertebrate clades in Earth’s history. Based on bone mass decrease and cosmopolitan distribution, both of which affect lifestyle, indications of parental care, and oxygen isotope analyses, evidence for endothermy in plesiosaurs has accumulated. Recent bone histological investigations also provide evidence of fast growth and elevated metabolic rates. However, quantitative estimations of metabolic rates and bone growth rates in plesiosaurs have not been attempted before. Methods Phylogenetic eigenvector maps is a method for estimating trait values from a predictor variable while taking into account phylogenetic relationships. As predictor variable, this study employs vascular density, measured in bone histological sections of fossil eosauropterygians and extant comparative taxa. We quantified vascular density as primary osteon density, thus, the proportion of vascular area (including lamellar infillings of primary osteons) to total bone area. Our response variables are bone growth rate (expressed as local bone apposition rate) and resting metabolic rate (RMR). Results Our models reveal bone growth rates and RMRs for plesiosaurs that are in the range of birds, suggesting that plesiosaurs were endotherm. Even for basal eosauropterygians we estimate values in the range of mammals or higher. Discussion Our models are influenced by the availability of comparative data, which are lacking for large marine amniotes, potentially skewing our results. However, our statistically robust inference of fast growth and fast metabolism is in accordance with other evidence for plesiosaurian endothermy. Endothermy may explain the success of plesiosaurs consisting in their survival of the end-Triassic extinction event and their global radiation and dispersal.
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Affiliation(s)
- Corinna V Fleischle
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Tanja Wintrich
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - P Martin Sander
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.,Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, USA
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33
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Myhrvold NP. Response to formal comment on Myhrvold (2016) submitted by Griebeler and Werner (2017). PLoS One 2018; 13:e0192912. [PMID: 29489880 PMCID: PMC5831047 DOI: 10.1371/journal.pone.0192912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/20/2018] [Indexed: 11/19/2022] Open
Abstract
Griebeler and Werner offer a formal comment on Myhrvold, 2016 defending the conclusions of Werner and Griebeler, 2014. Although the comment criticizes several aspects of methodology in Myhrvold, 2016, all three papers concur on a key conclusion: the metabolism of extant endotherms and ectotherms cannot be reliably classified using growth-rate allometry, because the growth rates of extant endotherms and ectotherms overlap. A key point of disagreement is that the 2014 paper concluded that despite this general case, one can nevertheless classify dinosaurs as ectotherms from their growth rate allometry. The 2014 conclusion is based on two factors: the assertion (made without any supporting arguments) that the comparison with dinosaurs must be restricted only to extant sauropsids, ignoring other vertebrate groups, and that extant sauropsid endotherm and ectotherm growth rates in a data set studied in the 2014 work do not overlap. The Griebeler and Werner formal comment presents their first arguments in support of the restriction proposition. In this response I show that this restriction is unsupported by established principles of phylogenetic comparison. In addition, I show that the data set studied in their 2014 work does show overlap, and that this is visible in one of its figures. I explain how either point effectively invalidates the conclusion of their 2014 paper. I also address the other methodological criticisms of Myhrvold 2016, and find them unsupported.
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34
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Falcón W, Baxter RP, Furrer S, Bauert M, Hatt J, Schaepman‐Strub G, Ozgul A, Bunbury N, Clauss M, Hansen DM. Patterns of activity and body temperature of Aldabra giant tortoises in relation to environmental temperature. Ecol Evol 2018; 8:2108-2121. [PMID: 29468029 PMCID: PMC5817133 DOI: 10.1002/ece3.3766] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/19/2017] [Accepted: 12/06/2017] [Indexed: 11/25/2022] Open
Abstract
We studied the temperature relations of wild and zoo Aldabra giant tortoises (Aldabrachelys gigantea) focusing on (1) the relationship between environmental temperature and tortoise activity patterns (n = 8 wild individuals) and (2) on tortoise body temperature fluctuations, including how their core and external body temperatures vary in relation to different environmental temperature ranges (seasons; n = 4 wild and n = 5 zoo individuals). In addition, we surveyed the literature to review the effect of body mass on core body temperature range in relation to environmental temperature in the Testudinidae. Diurnal activity of tortoises was bimodally distributed and influenced by environmental temperature and season. The mean air temperature at which activity is maximized was 27.9°C, with a range of 25.8-31.7°C. Furthermore, air temperature explained changes in the core body temperature better than did mass, and only during the coldest trial, did tortoises with higher mass show more stable temperatures. Our results, together with the overall Testudinidae overview, suggest that, once variation in environmental temperature has been taken into account, there is little effect of mass on the temperature stability of tortoises. Moreover, the presence of thermal inertia in an individual tortoise depends on the environmental temperatures, and we found no evidence for inertial homeothermy. Finally, patterns of core and external body temperatures in comparison with environmental temperatures suggest that Aldabra giant tortoises act as mixed conformer-regulators. Our study provides a baseline to manage the thermal environment of wild and rewilded populations of an important island ecosystem engineer species in an era of climate change.
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Affiliation(s)
- Wilfredo Falcón
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Rich P. Baxter
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | | | | | - Jean‐Michel Hatt
- Clinic for Zoo Animals, Exotic Pets and WildlifeVetsuisse FacultyUniversity of ZurichZurichSwitzerland
| | - Gabriela Schaepman‐Strub
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Nancy Bunbury
- Seychelles Islands FoundationPO Box 853, MaheSeychelles
| | - Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and WildlifeVetsuisse FacultyUniversity of ZurichZurichSwitzerland
| | - Dennis M. Hansen
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
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35
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Pate JH, Salmon M. Ontogenetic Niches and the Development of Body Shape in Juvenile Sea Turtles. CHELONIAN CONSERVATION AND BIOLOGY 2017. [DOI: 10.2744/ccb-1274.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jessica H. Pate
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431-0991 USA[]
| | - Michael Salmon
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431-0991 USA[]
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36
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Gaspar P, Lalire M. A model for simulating the active dispersal of juvenile sea turtles with a case study on western Pacific leatherback turtles. PLoS One 2017; 12:e0181595. [PMID: 28746389 PMCID: PMC5528265 DOI: 10.1371/journal.pone.0181595] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/03/2017] [Indexed: 11/18/2022] Open
Abstract
Oceanic currents are known to broadly shape the dispersal of juvenile sea turtles during their pelagic stage. Accordingly, simple passive drift models are widely used to investigate the distribution at sea of various juvenile sea turtle populations. However, evidence is growing that juveniles do not drift purely passively but also display some swimming activity likely directed towards favorable habitats. We therefore present here a novel Sea Turtle Active Movement Model (STAMM) in which juvenile sea turtles actively disperse under the combined effects of oceanic currents and habitat-driven movements. This model applies to all sea turtle species but is calibrated here for leatherback turtles (Dermochelys coriacea). It is first tested in a simulation of the active dispersal of juveniles originating from Jamursba-Medi, a main nesting beach of the western Pacific leatherback population. Dispersal into the North Pacific Ocean is specifically investigated. Simulation results demonstrate that, while oceanic currents broadly shape the dispersal area, modeled habitat-driven movements strongly structure the spatial and temporal distribution of juveniles within this area. In particular, these movements lead juveniles to gather in the North Pacific Transition Zone (NPTZ) and to undertake seasonal north-south migrations. More surprisingly, juveniles in the NPTZ are simulated to swim mostly towards west which considerably slows down their progression towards the American west coast. This increases their residence time, and hence the risk of interactions with fisheries, in the central and eastern part of the North Pacific basin. Simulated habitat-driven movements also strongly reduce the risk of cold-induced mortality. This risk appears to be larger among the juveniles that rapidly circulate into the Kuroshio than among those that first drift into the North Equatorial Counter Current (NECC). This mechanism might induce marked interannual variability in juvenile survival as the strength and position of the NECC are directly linked to El Niño activity.
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Affiliation(s)
- Philippe Gaspar
- Sustainable Management of Marine Resources, Collecte Localisation Satellite, Ramonville-Saint-Agne, France
| | - Maxime Lalire
- Sustainable Management of Marine Resources, Collecte Localisation Satellite, Ramonville-Saint-Agne, France
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37
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Abstract
Thermal tolerances are affected by the range of temperatures that species encounter in their habitat. Daniel Janzen hypothesized in his “Why mountain passes are higher in the tropics” that temperature gradients were effective barriers to animal movements where climatic uniformity was high. Sea turtles bury their eggs providing some thermal stability that varies with depth. We assessed the relationship between thermal uniformity and thermal tolerance in nests of three species of sea turtles. We considered that barriers were “high” when small thermal changes had comparatively large effects and “low” when the effects were small. Mean temperature was lower and fluctuated less in species that dig deeper nests. Thermal barriers were comparatively “higher” in leatherback turtle (Dermochelys coriacea) nests, which were the deepest, as embryo mortality increased at lower “high” temperatures than in olive ridley (Lepidochelys olivacea) and green turtle (Chelonia mydas) nests. Sea turtles have temperature-dependent sex determination (TSD) and embryo mortality increased as temperature approached the upper end of the transitional range of temperatures (TRT) that produces both sexes (temperature producing 100% female offspring) in leatherback and olive ridley turtles. As thermal barriers are “higher” in some species than in others, the effects of climate warming on embryo mortality is likely to vary among sea turtles. Population resilience to climate warming may also depend on the balance between temperatures that produce female offspring and those that reduce embryo survival.
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Myhrvold NP. Dinosaur Metabolism and the Allometry of Maximum Growth Rate. PLoS One 2016; 11:e0163205. [PMID: 27828977 PMCID: PMC5102473 DOI: 10.1371/journal.pone.0163205] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 09/06/2016] [Indexed: 12/29/2022] Open
Abstract
The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth rates of extant groups are found to have a great deal of overlap, including between groups with endothermic and ectothermic metabolism. Dinosaur growth rates show similar overlap, matching the rates found for mammals, reptiles and fish. The allometric scaling of growth rate with mass is found to have curvature (on a log-log scale) for many groups, contradicting the prevailing view that growth rate allometry follows a simple power law. Reanalysis shows that no correlation between growth rate and basal metabolic rate (BMR) has been demonstrated. These findings drive a conclusion that growth rate allometry studies to date cannot be used to determine dinosaur metabolism as has been previously argued.
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Affiliation(s)
- Nathan P. Myhrvold
- Intellectual Ventures, Bellevue, Washington, United States of America
- * E-mail:
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39
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Davenport J, Jones TT, Work TM, Balazs GH. Topsy-turvy: turning the counter-current heat exchange of leatherback turtles upside down. Biol Lett 2016; 11:rsbl.2015.0592. [PMID: 26445982 DOI: 10.1098/rsbl.2015.0592] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Counter-current heat exchangers associated with appendages of endotherms feature bundles of closely applied arteriovenous vessels. The accepted paradigm is that heat from warm arterial blood travelling into the appendage crosses into cool venous blood returning to the body. High core temperature is maintained, but the appendage functions at low temperature. Leatherback turtles have elevated core temperatures in cold seawater and arteriovenous plexuses at the roots of all four limbs. We demonstrate that plexuses of the hindlimbs are situated wholly within the hip musculature, and that, at the distal ends of the plexuses, most blood vessels supply or drain the hip muscles, with little distal vascular supply to, or drainage from the limb blades. Venous blood entering a plexus will therefore be drained from active locomotory muscles that are overlaid by thick blubber when the adults are foraging in cold temperate waters. Plexuses maintain high limb muscle temperature and avoid excessive loss of heat to the core, the reverse of the accepted paradigm. Plexuses protect the core from overheating generated by muscular thermogenesis during nesting.
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Affiliation(s)
- John Davenport
- School of Biological, Earth and Environmental Sciences, University College Cork, North Mall Campus, Distillery Fields, Cork, Ireland
| | - T Todd Jones
- NOAA Fisheries, Pacific Islands Fisheries Science Center, 1845 Wasp Boulevard, Building 176, Honolulu, HI 96818, USA
| | - Thierry M Work
- US Geological Survey, National Wildlife Health Center, Honolulu Field Station, Honolulu, HI 96850, USA
| | - George H Balazs
- NOAA Fisheries, Pacific Islands Fisheries Science Center, 1845 Wasp Boulevard, Building 176, Honolulu, HI 96818, USA
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Lambertz M. Recent advances on the functional and evolutionary morphology of the amniote respiratory apparatus. Ann N Y Acad Sci 2016; 1365:100-13. [PMID: 27037667 DOI: 10.1111/nyas.13022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 12/30/2022]
Abstract
Increased organismic complexity in metazoans was achieved via the specialization of certain parts of the body involved in different faculties (structure-function complexes). One of the most basic metabolic demands of animals in general is a sufficient supply of all tissues with oxygen. Specialized structures for gas exchange (and transport) consequently evolved many times and in great variety among bilaterians. This review focuses on some of the latest advancements that morphological research has added to our understanding of how the respiratory apparatus of the primarily terrestrial vertebrates (amniotes) works and how it evolved. Two main components of the respiratory apparatus, the lungs as the "exchanger" and the ventilatory apparatus as the "active pump," are the focus of this paper. Specific questions related to the exchanger concern the structure of the lungs of the first amniotes and the efficiency of structurally simple snake lungs in health and disease, as well as secondary functions of the lungs in heat exchange during the evolution of sauropod dinosaurs. With regard to the active pump, I discuss how the unique ventilatory mechanism of turtles evolved and how understanding the avian ventilatory strategy affects animal welfare issues in the poultry industry.
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Affiliation(s)
- Markus Lambertz
- Institut für Zoologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
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41
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Lee SA. Incubation times of dinosaur eggs via embryonic metabolism. Phys Rev E 2016; 94:022402. [PMID: 27627330 DOI: 10.1103/physreve.94.022402] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 11/07/2022]
Abstract
The incubation times for the eggs of 21 dinosaurs are determined from an estimate of their embyronic metabolic rate and the mass of the hatchlings via a mass growth model based on conservation of energy. Embryos in extant birds and crocodiles are studied in order to determine the best model for embryonic metabolism and growth. These results are used to develop a theoretical model that predicts the incubation times of an egg. This model is applied to dinosaur eggs and provides a unique window into dinosaur reproduction. The dinosaurs studied come from both Saurischia and Ornithischia. The incubation times vary from about 28 days for Archaeopteryx lithographica to about 76 days for Alamosaurus sanjuanensis.
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Affiliation(s)
- Scott A Lee
- Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
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42
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Burns TJ, Davidson H, Kennedy MW. Large-scale investment in the excavation and “camouflaging” phases by nesting Leatherback Turtles ( Dermochelys coriacea). CAN J ZOOL 2016. [DOI: 10.1139/cjz-2015-0240] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nesting female Leatherback Turtles (Dermochelys coriacea (Vandelli, 1761)) are ungainly and vulnerable to predation, stranding, and physiological stress, dangers encountered repeatedly in a nesting season. Minimising these risks must be balanced against optimising investment in nest-site selection, excavation, refilling, and concealment of their egg clutches. We investigated the relative investment in the different phases of nesting in Leatherback Turtles by recording the duration of, and respiratory frequency during, each phase. Nest excavation and the final sand scattering (usually termed “camouflage” or “disguise”) phases were the longest in duration. By combining the relative durations of nesting phases with literature estimates of oxygen consumption, we found that these may be the most expensive phases energetically, sand scattering in particular. Leatherback Turtles follow convoluted paths during the sand scattering phase, which were mapped and measured. They disturb large areas (mean (±SD) 30.3 ± 11.1 m2, maximum 57 m2), the centroids of which were always offset from the nest itself. Interestingly, in none of 26 nestings observed did the centre line of females move over the nest itself. Nesting Leatherbacks therefore invest heavily in obscuring the egg clutch, and the pattern of their movements in doing so suggests decoy behaviour.
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Affiliation(s)
- Thomas J. Burns
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Hannah Davidson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Malcolm W. Kennedy
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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43
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Lovegrove BG. A phenology of the evolution of endothermy in birds and mammals. Biol Rev Camb Philos Soc 2016; 92:1213-1240. [DOI: 10.1111/brv.12280] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Barry G. Lovegrove
- School of Life Sciences; University of KwaZulu-Natal; P/Bag X01 Scottsville Pietermaritzburg 3209 South Africa
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Vermeij GJ. Gigantism and Its Implications for the History of Life. PLoS One 2016; 11:e0146092. [PMID: 26771527 PMCID: PMC4714876 DOI: 10.1371/journal.pone.0146092] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 12/14/2015] [Indexed: 11/19/2022] Open
Abstract
Gigantism-very large body size-is an ecologically important trait associated with competitive superiority. Although it has been studied in particular cases, the general conditions for the evolution and maintenance of gigantism remain obscure. I compiled sizes and dates for the largest species in 3 terrestrial and 7 marine trophic and habitat categories of animals from throughout the Phanerozoic. The largest species (global giants) in all categories are of post-Paleozoic age. Gigantism at this level appeared tens to hundreds of millions of years after mass extinctions and long after the origins of clades in which it evolved. Marine gigantism correlates with high planktic or seafloor productivity, but on land the correspondence between productivity and gigantism is weak at best. All global giants are aerobically active animals, not gentle giants with low metabolic demands. Oxygen concentration in the atmosphere correlates with gigantism in the Paleozoic but not thereafter, likely because of the elaboration of efficient gas-exchange systems in clades containing giants. Although temperature and habitat size are important in the evolution of very large size in some cases, the most important (and rare) enabling circumstance is a highly developed ecological infrastructure in which essential resources are abundant and effectively recycled and reused, permitting activity levels to increase and setting the stage for gigantic animals to evolve. Gigantism as a hallmark of competitive superiority appears to have lost its luster on land after the Mesozoic in favor of alternative means of achieving dominance, especially including social organization and coordinated food-gathering.
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Affiliation(s)
- Geerat J. Vermeij
- Department of Earth and Planetary Sciences, University of California, One Shields Avenue, Davis, California, 95616, United States of America
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45
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Climate change impacts on nesting and internesting leatherback sea turtles using 3D animated computational fluid dynamics and finite volume heat transfer. Ecol Modell 2016. [DOI: 10.1016/j.ecolmodel.2015.10.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Isotopic ordering in eggshells reflects body temperatures and suggests differing thermophysiology in two Cretaceous dinosaurs. Nat Commun 2015; 6:8296. [PMID: 26462135 DOI: 10.1038/ncomms9296] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 08/07/2014] [Indexed: 01/17/2023] Open
Abstract
Our understanding of the evolutionary transitions leading to the modern endothermic state of birds and mammals is incomplete, partly because tools available to study the thermophysiology of extinct vertebrates are limited. Here we show that clumped isotope analysis of eggshells can be used to determine body temperatures of females during periods of ovulation. Late Cretaceous titanosaurid eggshells yield temperatures similar to large modern endotherms. In contrast, oviraptorid eggshells yield temperatures lower than most modern endotherms but ∼ 6 °C higher than co-occurring abiogenic carbonates, implying that this taxon did not have thermoregulation comparable to modern birds, but was able to elevate its body temperature above environmental temperatures. Therefore, we observe no strong evidence for end-member ectothermy or endothermy in the species examined. Body temperatures for these two species indicate that variable thermoregulation likely existed among the non-avian dinosaurs and that not all dinosaurs had body temperatures in the range of that seen in modern birds.
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Lee SA. Metabolism of dinosaurs as determined from their growth. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032706. [PMID: 26465497 DOI: 10.1103/physreve.92.032706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Indexed: 06/05/2023]
Abstract
A model based on cellular properties is used to analyze the mass growth curves of 20 dinosaurs. This analysis yields the first measurement of the average cellular metabolism of dinosaurs. The organismal metabolism is also determined. The cellular metabolism of dinosaurs is found to decrease with mass at a slower rate than is observed in extant animals. The organismal metabolism increases with the mass of the dinosaur. These results come from both the Saurischia and Ornithischia branches of Dinosauria, suggesting that the observed metabolic features were common to all dinosaurs. The results from dinosaurs are compared to data from extant placental and marsupial mammals, a monotreme, and altricial and precocial birds, reptiles, and fish. Dinosaurs had cellular and organismal metabolisms in the range observed in extant mesotherms.
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Affiliation(s)
- Scott A Lee
- Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
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48
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Burns TJ, McCafferty DJ, Kennedy MW. Core and body surface temperatures of nesting leatherback turtles (Dermochelys coriacea). J Therm Biol 2015; 51:15-22. [DOI: 10.1016/j.jtherbio.2015.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 02/27/2015] [Accepted: 03/01/2015] [Indexed: 10/23/2022]
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McClain CR, Balk MA, Benfield MC, Branch TA, Chen C, Cosgrove J, Dove ADM, Gaskins L, Helm RR, Hochberg FG, Lee FB, Marshall A, McMurray SE, Schanche C, Stone SN, Thaler AD. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 2015; 3:e715. [PMID: 25649000 PMCID: PMC4304853 DOI: 10.7717/peerj.715] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/10/2014] [Indexed: 11/20/2022] Open
Abstract
What are the greatest sizes that the largest marine megafauna obtain? This is a simple question with a difficult and complex answer. Many of the largest-sized species occur in the world’s oceans. For many of these, rarity, remoteness, and quite simply the logistics of measuring these giants has made obtaining accurate size measurements difficult. Inaccurate reports of maximum sizes run rampant through the scientific literature and popular media. Moreover, how intraspecific variation in the body sizes of these animals relates to sex, population structure, the environment, and interactions with humans remains underappreciated. Here, we review and analyze body size for 25 ocean giants ranging across the animal kingdom. For each taxon we document body size for the largest known marine species of several clades. We also analyze intraspecific variation and identify the largest known individuals for each species. Where data allows, we analyze spatial and temporal intraspecific size variation. We also provide allometric scaling equations between different size measurements as resources to other researchers. In some cases, the lack of data prevents us from fully examining these topics and instead we specifically highlight these deficiencies and the barriers that exist for data collection. Overall, we found considerable variability in intraspecific size distributions from strongly left- to strongly right-skewed. We provide several allometric equations that allow for estimation of total lengths and weights from more easily obtained measurements. In several cases, we also quantify considerable geographic variation and decreases in size likely attributed to humans.
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Affiliation(s)
- Craig R McClain
- National Evolutionary Synthesis Center , Durham, NC , USA ; Department of Biology, Duke University , Durham, NC , USA
| | - Meghan A Balk
- Department of Biology, University of New Mexico , Albuquerque, NM , USA
| | - Mark C Benfield
- Department of Oceanography and Coastal Sciences, Louisiana State University , Baton Rouge, LA , USA
| | - Trevor A Branch
- School of Aquatic & Fishery Sciences, University of Washington , Seattle, WA , USA
| | - Catherine Chen
- Department of Biology, Duke University , Durham, NC , USA
| | - James Cosgrove
- Natural History Section, Royal British Columbia Museum , Victoria, BC , Canada
| | | | - Leo Gaskins
- Department of Biology, Duke University , Durham, NC , USA
| | - Rebecca R Helm
- Department of Ecology and Evolutionary Biology, Brown University , Providence, RI , USA
| | - Frederick G Hochberg
- Department of Invertebrate Zoology, Santa Barbara Museum of Natural History , Santa Barbara, CA , USA
| | - Frank B Lee
- Department of Biology, Duke University , Durham, NC , USA
| | | | - Steven E McMurray
- Department of Biology and Marine Biology, University of North Carolina Wilmington , Wilmington, NC , USA
| | | | - Shane N Stone
- Department of Biology, Duke University , Durham, NC , USA
| | - Andrew D Thaler
- Blackbeard Biologic: Science and Environmental Advisors , Vallejo, CA , USA
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50
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Casey JP, James MC, Williard AS. Behavioral and metabolic contributions to thermoregulation in freely swimming leatherback turtles at high latitudes. J Exp Biol 2014; 217:2331-7. [DOI: 10.1242/jeb.100347] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Leatherback turtles in the Northwest Atlantic Ocean have a broad geographic range that extends from nesting beaches near the equator to seasonal foraging grounds as far north as Canada. The ability of leatherbacks to maintain core body temperature (Tb) higher than that of the surrounding water is thought to be a key element of their biology that permits them to exploit productive waters at high latitudes. We provide the first recordings of Tb from freely swimming leatherbacks at a northern foraging ground, and use these data to assess the importance of behavioral adjustments and metabolic sources of heat for maintenance of the thermal gradient (Tg). The mean Tb for individual leatherbacks ranged from 25.4±1.7 to 27.3±0.3°C, and Tg ranged from 10.7±2.4 to 12.1±1.7°C. Variation in mean Tb was best explained by the amount of time that turtles spent in the relatively warm surface waters. A diel trend in Tb was apparent, with daytime cooling suggestive of prey ingestion and night-time warming attributable to endogenous heat production. We estimate that metabolic rates necessary to support the observed Tg are ~3 times higher than resting metabolic rate, and that specific dynamic action is an important source of heat for foraging leatherbacks.
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Affiliation(s)
- James P. Casey
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA
- Department of Biology, Barnard College, New York, NY 10027, USA
| | - Michael C. James
- Fisheries and Oceans Canada, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, NS, Canada, B2Y 4A2
| | - Amanda S. Williard
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA
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