Magnetic Maps in Animals: A Theory Comes of Age?

Freake, Michael J.; Muheim, Rachel; Phillips, John B.

doi:10.1086/511528

Cited by 102 publications

(101 citation statements)

References 82 publications

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“…This led the authors to hypothesize that foraging sites used by sea turtles reflect their previous experiences as hatchlings and young juveniles, a hypothesis also evoked by Fossette et al (2010b) to explain the observed foraging ground distribution of leatherbacks in the North Atlantic. This idea can actually be traced back to earlier works of Lohmann et al (1999Lohmann et al ( , 2008 and Freake et al (2006) who proposed that sea turtles might progressively develop a magnetic map of the oceanic areas visited for use later in life, based on their ability to detect variations in the Earth's magnetic field (Lohmann & 275 Fig. 8.…”

Section: Basis For Analyzing Model Resultsmentioning

confidence: 99%

Oceanic dispersal of juvenile leatherback turtles: going beyond passive drift modeling

Gaspar

Benson

Dutton

et al. 2012

Mar. Ecol. Prog. Ser.

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The current paper presents the first detailed investigation of open-ocean dispersal of hatchlings and juveniles of the critically endangered western Pacific leatherback turtle Dermochelys coriacea populations nesting in New Guinea. Dispersal patterns were simulated by releasing particles drifting passively, or almost passively, into a state-of-the-art World Ocean circulation model. Analysis of the simulation results combined with sighting, genetic, bycatch, and adult satellite tracking information reveals that: (1) Hatchlings emerging from the main New Guinea nesting beaches are likely to be entrained by highly variable oceanic currents into the North Pacific, South Pacific, or Indian Oceans. Those drifting into the Indian Ocean likely suffer very high mortality. This suggests that, as ocean current variability determines the partition of hatchlings into different dispersal areas, it also largely influences juvenile survival rate at the population level. (2) Within 1 to 2 yr, most passively drifting juveniles reach temperate oceanic regions where the water temperature in winter drops well below the minimum temperature likely tolerated by such small individuals. This leads us to hypothesize that, after an initial period of mostly passive drift, juveniles initiate active swimming towards lower (warmer) latitudes before winter and back again towards higher latitudes, where food abounds, during spring. Such seasonal migrations would significantly slow the eastward progression of individuals circulating in the North Pacific current. This slower drift scenario better explains the size distribution of leatherbacks observed, or incidentally caught by pelagic fisheries, in the North Pacific. This dispersal mechanism combining passive drift with active habitat-driven seasonal migrations might well apply to many other sea turtle populations and deserves further study.

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Section: Basis For Analyzing Model Resultsmentioning

confidence: 99%

Oceanic dispersal of juvenile leatherback turtles: going beyond passive drift modeling

Gaspar

Benson

Dutton

et al. 2012

Mar. Ecol. Prog. Ser.

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“…An alternative hypothesis is that the manipulation did not affect the compass sense but instead a magnetic map sense. A magnetic map would be based on detection of an increase/decrease in intensity and/or inclination, allowing the animal to perceive at least their latitude of displacement in a normal magnetic field (6,21). It has also been proposed that homing pigeons can learn the directional characteristics of map factors at a home site (22) and that rotation of the direction of those factors at the home site results in a corresponding rotation, and thus a misreading, of the map (23).…”

Section: Discussionmentioning

confidence: 99%

“…As a general notion, animals could potentially use the geomagnetic field for obtaining directional information, the "compass sense" (5), and/or to locate position, the "map sense" (6). In birds, a number of seemingly contradictory findings suggested that the geomagnetic field interacts with either the sun or the stars to provide directional information (7).…”

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confidence: 99%

A nocturnal mammal, the greater mouse-eared bat, calibrates a magnetic compass by the sun

Holland

Borissov

Siemers

2010

Proc. Natl. Acad. Sci. U.S.A.

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Recent evidence suggests that bats can detect the geomagnetic field, but the way in which this is used by them for navigation to a home roost remains unresolved. The geomagnetic field may be used by animals both to indicate direction and to locate position. In birds, directional information appears to be derived from an interaction of the magnetic field with either the sun or the stars, with some evidence suggesting that sunset/sunrise provides the primary directional reference by which a magnetic compass is calibrated daily. We demonstrate that homing greater mouseeared bats (Myotis myotis) calibrate a magnetic compass with sunset cues by testing their homing response after exposure to an altered magnetic field at and after sunset. Magnetic manipulation at sunset resulted in a counterclockwise shift in orientation compared with controls, consistent with sunset calibration of the magnetic field, whereas magnetic manipulation after sunset resulted in no change in orientation. Unlike in birds, however, the pattern of polarization was not necessary for the calibration. For animals that occupy ecological niches where the sunset is rarely observed, this is a surprising finding. Yet it may indicate the primacy of the sun as an absolute geographical reference not only for birds but also within other vertebrate taxa.navigation | orientation | sun compass | Chiroptera | sensory ecology S ince the discovery that migrating birds can use the geomagnetic field to designate direction, research on the manner in which different animals use this cue for orientation and navigation has flourished (1-4). As a general notion, animals could potentially use the geomagnetic field for obtaining directional information, the "compass sense" (5), and/or to locate position, the "map sense" (6). In birds, a number of seemingly contradictory findings suggested that the geomagnetic field interacts with either the sun or the stars to provide directional information (7). Calibration by such celestial cues may be important in migrating animals to correct for declination error [the difference between geographical and magnetic north (8)] or to avoid increased paths through inaccuracies (9). Recent evidence suggests that polarized light cues at sunset and sunrise may provide the primary directional reference that calibrates a magnetic compass in migrating birds (8)(9)(10)(11).Surprisingly, only recently has it been shown that bats are able to detect the geomagnetic field (12-14), although so far evidence exists only for two species, one in the United States (12, 13) and one in Asia (14). Using the technique of Cochran et al. (8), in which the animal is exposed to an altered magnetic field at sunset and then released into the natural magnetic field, the results of ref. 12 suggested that, like birds, bats used the geomagnetic field to determine direction following calibration by sunset cues. However, this interpretation remains uncertain on two counts. First, the experimental design in ref. 12 involved transport in a variable magnetic field, making it...

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“…Such multimodal integration allows information from multiple directional cues to be calibrated. This calibration is critical to spatial navigation under natural conditions (29).…”

Section: Parallel Map Solutionmentioning

confidence: 99%

From chemotaxis to the cognitive map: The function of olfaction

Jacobs

2012

Proc. Natl. Acad. Sci. U.S.A.

169

176

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A paradox of vertebrate brain evolution is the unexplained variability in the size of the olfactory bulb (OB), in contrast to other brain regions, which scale predictably with brain size. Such variability appears to be the result of selection for olfactory function, yet there is no obvious concordance that would predict the causal relationship between OB size and behavior. This discordance may derive from assuming the primary function of olfaction is odorant discrimination and acuity. If instead the primary function of olfaction is navigation, i.e., predicting odorant distributions in time and space, variability in absolute OB size could be ascribed and explained by variability in navigational demand. This olfactory spatial hypothesis offers a single functional explanation to account for patterns of olfactory system scaling in vertebrates, the primacy of olfaction in spatial navigation, even in visual specialists, and proposes an evolutionary scenario to account for the convergence in olfactory structure and function across protostomes and deuterostomes. In addition, the unique percepts of olfaction may organize odorant information in a parallel map structure. This could have served as a scaffold for the evolution of the parallel map structure of the mammalian hippocampus, and possibly the arthropod mushroom body, and offers an explanation for similar flexible spatial navigation strategies in arthropods and vertebrates.sensory | memory | orientation | limbic

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Magnetic Maps in Animals: A Theory Comes of Age?

Cited by 102 publications

References 82 publications

Oceanic dispersal of juvenile leatherback turtles: going beyond passive drift modeling

Oceanic dispersal of juvenile leatherback turtles: going beyond passive drift modeling

A nocturnal mammal, the greater mouse-eared bat, calibrates a magnetic compass by the sun

From chemotaxis to the cognitive map: The function of olfaction

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