The fur of mammals in exposed environments; do crypsis and thermal needs necessarily conflict? The polar bear and marsupial koala compared
The fur of mammals in exposed environments; do crypsis and thermal needs necessarily conflict? The polar bear and marsupial koala compared
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DOI：
10.1007/s00360-013-0794-8
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发表时间：
2014-02-01
影响因子：
2
通讯作者：
Maloney, Shane K.
中科院分区：
文献类型：
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作者：
Dawson, Terence J.;Webster, Koa N.;Maloney, Shane K.
哺乳动物的皮毛具有多种复杂的功能。除了体温调节，皮毛还涉及物理保护，感官输入，防水和着色，后者对于隐藏或伪装很重要。其中一些不同的功能可能会发生冲突。我们已经研究了哺乳动物皮毛中隐色和热特征的变化如何相互作用，并影响来自太阳辐射的潜在热流入，其中大部分是在可见光谱范围之外的。北极熊（Ursus maritimus）和有袋动物考拉（Phascolarctus cinereus）的皮毛在隔热方面有相似之处，但是，虽然它们的颜色都很隐蔽，但它们的颜色却截然不同，即白色和深灰色。用光谱辐射计测量了大衣在整个太阳光谱上对太阳辐射的反射率。通过将这些涂层安装在风洞中的热流传感器/温控板装置上，确定了在一定风速范围内入射太阳辐射和由此产生的热流的调制。一盏具有类似太阳光谱的辐射光谱分布的灯被用来代替太阳。在可见光谱范围内，这两种植物的颜色匹配具有明显的隐性，海洋木与雪相匹配，森林木与桉树树叶相匹配。虽然在整个太阳光谱上的反射率有明显的不同，海洋藻的反射率为66%，而灰脊灰藻的反射率为10%，但太阳辐射到达皮肤的热流是相似的。在低风速（1 m s(-1)）下，19%的入射太阳辐射在皮肤表面以热的形式受到影响；在更高的风速（10米每秒（-1））下，这一比例下降到大约10%。海熊和灰熊的皮毛绝缘程度相当高，尽管它们的皮毛的反射率和穿透太阳辐射的深度不同，但相当大的绝缘性限制了到达皮肤的辐射热。这些数据表明，一般来说，如果哺乳动物的皮毛具有很高的绝缘性，那么从太阳辐射流入动物体内的热量就会受到很大限制，皮毛颜色的影响可以忽略不计。然而，与其他物种的已发表数据的比较表明，随着皮毛绝缘性的降低，颜色对与太阳辐射相关的热流入的影响越来越大。
The furs of mammals have varied and complex functions. Other than for thermoregulation, fur is involved in physical protection, sensory input, waterproofing and colouration, the latter being important for crypsis or camouflage. Some of these diverse functions potentially conflict. We have investigated how variation in cryptic colouration and thermal features may interact in the coats of mammals and influence potential heat inflows from solar radiation, much of which is outside the visible spectral range. The coats of the polar bear (Ursus maritimus) and the marsupial koala (Phascolarctus cinereus) have insulative similarities but, while they feature cryptic colouration, they are of contrasting colour, i.e. whitish and dark grey. The reflectance of solar radiation by coats was measured across the full solar spectrum using a spectroradiometer. The modulation of incident solar radiation and resultant heat flows in these coats were determined at a range of wind speeds by mounting them on a heat flux transducer/temperature-controlled plate apparatus in a wind tunnel. A lamp with a spectral distribution of radiation similar to the solar spectrum was used as a proxy for the sun. Crypsis by colour matching was apparent within the visible spectrum for the two species, U. maritimus being matched against snow and P. cinereus against Eucalyptus forest foliage. While reflectances across the full solar spectrum differed markedly, that of U. maritimus being 66 % as opposed to 10 % for P. cinereus, the heat influxes from solar radiation reaching the skin were similar. For both coats at low wind speed (1 m s(-1)), 19 % of incident solar radiation impacted as heat at the skin surface; at higher wind speed (10 m s(-1)) this decreased to approximately 10 %. Ursus maritimus and P. cinereus have high and comparable levels of fur insulation and although the patterns of reflectance and depths of penetrance of solar radiation differ for the coats, the considerable insulation limited the radiant heat reaching the skin. These data suggest that generally, if mammal coats have high insulation then heat flow from solar radiation into an animal is much restricted and the impact of coat colour is negligible. However, comparisons with published data from other species suggest that as fur insulation decreases, colour increasingly influences the heat inflow associated with solar radiation.