Wyniki wyszukiwania

1

Relative size of hearts and lungs of small bats

100%

Canals M., Atala C., Grossi B., Iriarte-Diaz J.

Acta Chiropterologica

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2005

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tom 07

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nr 1

We estimated the heart and lung size of several species of small bats (Tadarida brasiliensis, Mormopterus kalinowski, Myotis chiloensis, Histiotus macrotus, H. montanus, Lasiurus borealis and L. cinereus) and compared these values to those of bats of larger size and other mammals. Our results confirmed that bats have the largest relative heart and lung size of all mammals. This is associated with the high energetic costs of flight. As expected, the mass-specific lung and heart sizes of small bats were larger than those of large bats. However, although relative heart mass decreased according to body mass, Mb−0.21, lung volume was nearly isometric with body mass (exponent = 0.90). This exponent was close to unity, and between exponents reported previously (0.77 and 1.06). This suggests that small bats compensate the energetic cost of flight mainly by changes in cardiovascular morphology. The relative heart mass of both H. macrotus and H. montanus was particularly large, representing 1.71 and 2.18% of total body mass, respectively. These values correspond to 121.3 and 162.7%, respectively, of the expected values from allometric relationships. In these big-eared bats, the large hearts could be attributed to the energetic costs induced by the ears' drag.

2

Modulating factors of the energetic effectiveness of huddling in small mammals

100%

Canals M., Rosenmann M., Novoa F. F., Bozinovic F.

Acta Theriologica

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1998

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tom 43

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nr 4

Huddling is effective in decreasing metabolic rate permitting energy saving. However, this decrease varies among different species depending on physical, physiological and behavioral characteristics of the huddled individuals. Following a general model we analyzed the effects of ambient temperature, thermal conductance and ontogeny on the huddling effectiveness (energy saving level from huddling behaviour) in white mice Mus musculus. Also, we studied the effects of thermal conductance by using the Sigmodontine Abrothrix andinus as a model organism, To put our results in a general context we analyzed literature data of huddling of several species of rodents at different temperatures. No effects of temperature and thermal conductance was detected. However, based on literature data, we found that at temperatures lower or near thermoneutrality the huddling effectiveness decrease, Also, the huddling effectiveness depends on the stage of development. Temperature probably affects the intensity of huddling, while changes in huddling effectiveness at early stages of development are likely consequences of structural (morphological) changes during the ontogeny. In this sense, it appears that the capacity to change the body form is and individual structural constraint which is extended to the huddling group.

3

Geometrical aspects of the energetic effectiveness of huddling in small mammals

100%

Canals M., Rosenmann M., Bozinovic F.

Acta Theriologica

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1997

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tom 42

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nr 3

Reduced energy expenditure resulting from huddling in small mammals is mainly attributed to the reduced surface area/volume ratio of the huddling group. Here we propose a model to account for the reduction of the relative exposed area of grouped animals and for the diminution of metabolic rate during huddling. We attempt to explain mechanistically how changes in energy savings may operate. We applied our model to results obtained by grouping deformable bodies, and also laboratory measurements of oxygen consumption on huddling small mammals of four species. We found a small amount of diversity in the energetic efficiency of huddling. We estimate that the average relative area lost during huddling ranged between 28.7 and 39.1%. The average huddling effectiveness in the studied species was 42%, which is a significant fraction of the energy/matter budget of a small mammal, especially under winter conditions.

4

Biomechanic consequences of differences in wing morphology between Tadarida brasiliensis and Myotis chiloensis

100%

Iriarte-Diaz J., Novoa F. F., Canals M.

Acta Theriologica

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2002

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tom 47

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nr 2

The wing morphology of bats is very diverse, and may correlate with energetic, behavioural, and ecological demands. If these demands conflict, wing shape may reflect compromise solutions. In this study, we compared the wing morphology of two bats, Tadarida brasiliensis (Geoffroy, 1824) and Myotis chiloensis (Waterhouse, 1828), that differ in body size, habitat, and foraging behaviour. We analyzed features of bio- mechanical and energetic relevance, and sought evidence of compromise solutions to energetic, ecological, and behavioural demands. We found that wing span of both species conformed to expectations based on allometric relationships, but that although the wing area of M. chiloensis did not differ from predictions, the wing area of T. brasiliensis was lower. M. chiloensis possessed an unusually low second moment of area of the humerus. Wing form of M. chiloensis is consistent with highly maneuverable flight needed to live between shrubs and wooded habitats, and its low aspect ratio and low wing loading indicate a high energetic cost and a low flight speed, respectively. The low humeral second moment of area may be related to a reduction of wing mass and may result in decreased inertial power. In contrast, T. brasiliensis showed high aspect ratio and wing loading, characteristic of high speed, energetically economic flight.

Ograniczanie wyników

3 Acta Theriologica

1 Acta Chiropterologica

4 Canals M.

2 Bozinovic F.

2 Iriarte-Diaz J.

2 Novoa F. F.

2 Rosenmann M.

1 Atala C.

1 Grossi B.

1 2005

1 2002

1 1998

1 1997

Relative size of hearts and lungs of small bats

Modulating factors of the energetic effectiveness of huddling in small mammals

Geometrical aspects of the energetic effectiveness of huddling in small mammals

Biomechanic consequences of differences in wing morphology between Tadarida brasiliensis and Myotis chiloensis