This Ph.D. thesis focuses on the visual capabilities of subterranean
African mole-rats (family Bathyegidae) and a potential role of their
residual vision. We described basic visual capability of light/dark
discrimination and capacity to perceive short to medium-wavelength light
in the photopic range of intensities. Our behavioural findings revealed
severe visual deficits, implying visually guided spatial orientation in molerats
improbable. Our field study demostrated no light-correlated daily
activitivy pattern of mole-rats in the natural habitat. We described very
effective propagation of long wavelength light in breached burrows that
can be detected by mole-rats for long distances, in contary to short
wavelengths with very low propagation. Thus, an unique primary blue
light perception, described only in African mole-rats among all
mammalian species so far, has most probably no adaptive value and might
be only a result of arrested cone development. Mole-rats effectively
localized and plugged with soil illuminated sites under laboratory
conditions, supporting the hypothesis that low acuity residual vision play
an indispensable role in bathyergid anti-predatory behaviour and tunnel
maintanance but not in spatial orientation.
Klíčová slova
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Klíčová slova v angličtině
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Rozsah průvodní práce
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Jazyk
CZ
Anotace
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Anotace v angličtině
This Ph.D. thesis focuses on the visual capabilities of subterranean
African mole-rats (family Bathyegidae) and a potential role of their
residual vision. We described basic visual capability of light/dark
discrimination and capacity to perceive short to medium-wavelength light
in the photopic range of intensities. Our behavioural findings revealed
severe visual deficits, implying visually guided spatial orientation in molerats
improbable. Our field study demostrated no light-correlated daily
activitivy pattern of mole-rats in the natural habitat. We described very
effective propagation of long wavelength light in breached burrows that
can be detected by mole-rats for long distances, in contary to short
wavelengths with very low propagation. Thus, an unique primary blue
light perception, described only in African mole-rats among all
mammalian species so far, has most probably no adaptive value and might
be only a result of arrested cone development. Mole-rats effectively
localized and plugged with soil illuminated sites under laboratory
conditions, supporting the hypothesis that low acuity residual vision play
an indispensable role in bathyergid anti-predatory behaviour and tunnel
maintanance but not in spatial orientation.