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Mazza PPA, Buccianti A, Savorelli A. Grasping at straws: a re-evaluation of sweepstakes colonisation of islands by mammals. Biol Rev Camb Philos Soc 2019; 94:1364-1380. [PMID: 30864268 DOI: 10.1111/brv.12506] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 11/28/2022]
Abstract
Natural rafting is an easy, non-evidence-based solution often used to explain the presence of a variety of species on isolated islands. The question arises as to whether this solution is based on solid scientific grounds. It is a plausible colonisation route only if intricate networks of variables are considered and many different conditions satisfied. This review provides a descriptive account of some of the most critical issues underlying the theory of natural rafting that should be addressed by its supporters. These include: (i) biological variables; (ii) characteristics of the vessels; and (iii) physical variables. Natural rafting may explain the dispersal of poikilotherms with low metabolic rates and low resource requirements that could withstand trans-oceanic crossings, but explaining the transport of homeothermic terrestrial mammals to oceanic islands is more problematic. Drifting at sea exposes organisms to high concentrations of salt, high temperature and humidity excursions, starvation, and above all to dehydration. A sufficiently large group of healthy reproductive individuals of the two sexes should either be transported together, or be able to reassemble after separate crossings, to prevent inbreeding, genetic drift and ultimately extinction. Any vessels of flotsam occupied must minimally provide the animals they transport with sufficient provisions to survive the journey, offer minimum friction and drag through water, and be transported by appropriately directed, sustained, high-speed currents. Thus, a 'sweepstakes colonisation' event would be the result of a lucky combination of all, or at least the majority, of these factors. Some cases throw doubt on the use of a natural rafting model to explain known animal colonisations, with one of the most striking examples being Madagascar. This island is far from the nearest mainland coasts and the sea currents in the Mozambique Channel are directed towards Africa rather than Madagascar, yet, the island was colonised by terrestrial mammals (e.g. extinct hippopotamuses, lemurs, carnivores, rodents and tenrecs) unable to swim and to survive long journeys at sea. In order to assess the feasibility of the natural rafting model in a case such as Madagascar, tests were performed using three variables for which enough information could be obtained from the literature: length of survival without food, survival without water, and sea current speed. The distributions of these variables appear to be log-normal and multiplicative, or follow a power-law, rather than being Gaussian. The tests suggest that a distributional analysis is a more suitable approach than the use of geometric probability to calculate the probabilities associated with the examined data. Such non-linear and self-organising systems may reach a critical point governed by different competing factors. Mammals with high survival requirements, such as lemurs and hippopotamuses, thus may have a virtually zero probability of reaching distant islands by natural rafting. Our results raise doubts as to the validity of a natural rafting model, and we urge a rethinking of the modes in which numerous islands were colonised by land mammals and a careful revision of past geological and phylogeographic work.
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Affiliation(s)
- Paul P A Mazza
- Department of Earth Sciences, University of Florence, Via La Pira 4, Florence, Italy
| | - Antonella Buccianti
- Department of Earth Sciences, University of Florence, Via La Pira 4, Florence, Italy
| | - Andrea Savorelli
- Department of Earth Sciences, University of Florence, Via La Pira 4, Florence, Italy
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Ho JM, Bergeon Burns CM, Rendon NM, Rosvall KA, Bradshaw HB, Ketterson ED, Demas GE. Lipid signaling and fat storage in the dark-eyed junco. Gen Comp Endocrinol 2017; 247:166-173. [PMID: 28161439 PMCID: PMC5410188 DOI: 10.1016/j.ygcen.2017.01.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 12/13/2016] [Accepted: 01/28/2017] [Indexed: 12/11/2022]
Abstract
Seasonal hyperphagia and fattening promote survivorship in migratory and wintering birds, but reduced adiposity may be more advantageous during the breeding season. Factors such as photoperiod, temperature, and food predictability are known environmental determinants of fat storage, but the underlying neuroendocrine mechanisms are less clear. Endocannabinoids and other lipid signaling molecules regulate multiple aspects of energy balance including appetite and lipid metabolism. However, these functions have been established primarily in mammals; thus the role of lipid signals in avian fat storage remains largely undefined. Here we examined relationships between endocannabinoid signaling and individual variation in fat storage in captive white-winged juncos (Junco hyemalis aikeni) following a transition to long-day photoperiods. We report that levels of the endocannabinoid 2-arachidonoylglycerol (2-AG), but not anandamide (AEA), in furcular and abdominal fat depots correlate negatively with fat mass. Hindbrain mRNA expression of CB1 endocannabinoid receptors also correlates negatively with levels of fat, demonstrating that fatter animals experience less central and peripheral endocannabinoid signaling when in breeding condition. Concentrations of the anorexigenic lipid, oleoylethanolamide (OEA), also inversely relate to adiposity. These findings demonstrate unique and significant relationships between adiposity and lipid signaling molecules in the brain and periphery, thereby suggesting a potential role for lipid signals in mediating adaptive levels of fat storage.
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Affiliation(s)
- Jacqueline M Ho
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA.
| | - Christine M Bergeon Burns
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Nikki M Rendon
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Kimberly A Rosvall
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA; Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
| | - Heather B Bradshaw
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA; Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA; Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN 47405, USA
| | - Ellen D Ketterson
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Gregory E Demas
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA; Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
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Mitchell GW, Guglielmo CG, Wheelwright NT, Freeman-Gallant CR, Norris DR. Early life events carry over to influence pre-migratory condition in a free-living songbird. PLoS One 2011; 6:e28838. [PMID: 22194925 PMCID: PMC3241683 DOI: 10.1371/journal.pone.0028838] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 11/16/2011] [Indexed: 11/18/2022] Open
Abstract
Conditions experienced during development can have long-term consequences for individual success. In migratory songbirds, the proximate mechanisms linking early life events and survival are not well understood because tracking individuals across stages of the annual cycle can be extremely challenging. In this paper, we first use a 13 year dataset to demonstrate a positive relationship between 1st year survival and nestling mass in migratory Savannah sparrows (Passerculus sandwichensis). We also use a brood manipulation experiment to show that nestlings from smaller broods have higher mass in the nest relative to individuals from larger broods. Having established these relationships, we then use three years of field data involving multiple captures of individuals throughout the pre-migratory period and a multi-level path model to examine the hypothesis that conditions during development limit survival during migration by affecting an individual's ability to accumulate sufficient lean tissue and fat mass prior to migration. We found a positive relationship between fat mass during the pre-migratory period (Sept–Oct) and nestling mass and a negative indirect relationship between pre-migratory fat mass and fledging date. Our results provide the first evidence that conditions during development limit survival during migration through their effect on fat stores. These results are particularly important given recent evidence showing that body condition of songbirds at fledging is affected by climate change and anthropogenic changes to landscape structure.
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Affiliation(s)
- Greg W Mitchell
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
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Pettersson J, Hasselquist D. Fat deposition and migration capacity of robinserithacus rebeculaand goldcrestsregulus regulusat ottenby, Sweden. ACTA ACUST UNITED AC 2011. [DOI: 10.1080/03078698.1985.9673859] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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McCue MD. Starvation physiology: reviewing the different strategies animals use to survive a common challenge. Comp Biochem Physiol A Mol Integr Physiol 2010; 156:1-18. [PMID: 20060056 DOI: 10.1016/j.cbpa.2010.01.002] [Citation(s) in RCA: 427] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 12/30/2009] [Accepted: 01/03/2010] [Indexed: 11/26/2022]
Abstract
All animals face the possibility of limitations in food resources that could ultimately lead to starvation-induced mortality. The primary goal of this review is to characterize the various physiological strategies that allow different animals to survive starvation. The ancillary goals of this work are to identify areas in which investigations of starvation can be improved and to discuss recent advances and emerging directions in starvation research. The ubiquity of food limitation among animals, inconsistent terminology associated with starvation and fasting, and rationale for scientific investigations into starvation are discussed. Similarities and differences with regard to carbohydrate, lipid, and protein metabolism during starvation are also examined in a comparative context. Examples from the literature are used to underscore areas in which reporting and statistical practices, particularly those involved with starvation-induced changes in body composition and starvation-induced hypometabolism can be improved. The review concludes by highlighting several recent advances and promising research directions in starvation physiology. Because the hundreds of studies reviewed here vary so widely in their experimental designs and treatments, formal comparisons of starvation responses among studies and taxa are generally precluded; nevertheless, it is my aim to provide a starting point from which we may develop novel approaches, tools, and hypotheses to facilitate meaningful investigations into the physiology of starvation in animals.
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Affiliation(s)
- Marshall D McCue
- Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
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Davidson NC, Evans PR, Uttley JD. Geographical variation of protein reserves in birds: the pectoral muscle mass of Dunlins Calidris alpina in winter. J Zool (1987) 2009. [DOI: 10.1111/j.1469-7998.1986.tb04714.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ramenofsky M, Savard R, Greenwood MR. Seasonal and diel transitions in physiology and behavior in the migratory dark-eyed junco. Comp Biochem Physiol A Mol Integr Physiol 1999; 122:385-97. [PMID: 10422257 DOI: 10.1016/s1095-6433(99)00013-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Body mass, fat stores, activities of lipogenic and lipolytic enzymes, and plasma corticosterone were measured throughout seasonal and diel transitions from fall through spring encompassing the non-migratory stages of early and mid winter, the prealternate molt, and the spring migratory stage in captive dark-eyed juncos to determine the physiological mechanisms underlying adaptations for migration. On a seasonal basis, lipid enzymes and corticosterone varied little throughout the stages even though the birds underwent dramatic alterations in mass, fat deposition, behavior, and activation of the reproductive axis. By contrast, diel changes were found in lipogenesis, lipolysis, muscle lipoprotein lipase, and plasma corticosterone when comparing birds in the two phases of spring migration--active flight and resting, as during times of stopover. In these two phases of migration, coordination of the lipogenic and lipolytic systems appear to maximize storage of fatty acids during rest and delivery/utilization during flight. Diel patterns of corticosterone revealed fairly consistent peaks during the night time (23:00) throughout the nonmigratory period. The profile of this pattern altered during the migratory period with variation between the flight and resting phases. In sum, the results from these captive studies offer a new approach for studying the regulation of migratory physiology in free-living birds.
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Affiliation(s)
- M Ramenofsky
- Department of Biology, Vassar College, Poughkeepsie, NY 12601, USA.
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Newton SF. Body condition of a small passerine bird: ultrasonic assessment and significance in overwinter survival. J Zool (1987) 1993. [DOI: 10.1111/j.1469-7998.1993.tb02657.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Karlsson L, Persson K, Pettersson J, Walinder G. Fat‐weight relationships and migratory strategies in the RobinErithacus rubeculaat two stop‐over sites in south Sweden. ACTA ACUST UNITED AC 1988. [DOI: 10.1080/03078698.1988.9673940] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Baggott GK. The fat contents and flight ranges of four warbler species on migration in North Wales. ACTA ACUST UNITED AC 1986. [DOI: 10.1080/03078698.1986.9673876] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Bairlein F. Efficiency of food utilization during fat deposition in the long-distance migratory garden warbler, Sylvia borin. Oecologia 1985; 68:118-125. [PMID: 28310920 DOI: 10.1007/bf00379483] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/1985] [Indexed: 11/24/2022]
Abstract
1 Intake of food, fat, protein and carbohydrates and their fecal output were recorded during the annual body weight cycle of the garden warbler, and old-world longdistance migratory bird species, and the efficiencies of food and nutrient utilization, defined as the ratio (intake-fecal output)/intake, were calculated. 2. Gross food intake and food and nutrient utilization differed significantly between different phases of the birds' body weight cycle. 3. During premigratory fattening, both in "autumn" and "spring", food intake and utilization of fat, protein and carbohydrates were significantly higher than during the low body weight prefattening periods. 4. The increase in efficiency of nutrient utilization accounted for about 1/3 and the increase in gross food intake about 2/3 of all surplus energy for hyperlipogenesis in the premigratory periods of the garden warbler. 5. The seasonal changes in efficiency of food and nutrient utilization seem to be driven by a circannual timing mechanism.
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Affiliation(s)
- Franz Bairlein
- Physiological Ecology Section, Dept. of Zoology, University of Köln, Weyertal 119, D-5000, Köln 41, Federal Republic of Germany
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Jones MM. Diurnal variation in the distribution of lipid in the pectoralis muscle of the House sparrow (
Passer domesticus
). J Zool (1987) 1980. [DOI: 10.1111/j.1469-7998.1980.tb01479.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marilyn M. Jones
- Department of Anatomy, St. Thomas's Hospital Medical School, London
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