Pough F Harvey, Preest Marion R, Fusari Margaret H
Laboratory of Functional Ecology, Section of Ecology and Systematics, Corson Hall, Cornell University, Ithaca, NY 14853-2701, USA, , , , , , US.
University of California at Santa Cruz, Natural Reserves, 254A Applied Sciences, Santa Cruz, CA 95064, USA, , , , , , US.
Oecologia. 1997 Oct;112(3):351-361. doi: 10.1007/s004420050320.
Fossorial lizards differ in morphology from their surface-dwelling relatives. The Australian sphenomorphine skink genus Ctenotus consists of surface-dwelling species, and is closely related to the genus Lerista, which includes both surface-dwelling and fossorial species. Sand-swimming represents the derived condition and has evolved independently in several lineages of Lerista. The heads of lizards in the two genera differ in shape (blunt snout for Ctenotus versus wedge-shaped for Lerista) and in length relative to the body (approximately 20% of snout-vent length for Ctenotus versus 12% for sand-swimming Lerista). Do these specializations affect the sizes or types of prey that can be consumed by Lerista? We compared prey-handling by Ctenotus and Lerista to correlate morphological differences with differences in prey-handling ability, and to distinguish the effects of snout shape and head length. Feeding trials included three categories of insect prey that the lizards normally eat: soft-bodied larvae (Lepidoptera), hard-bodied larvae (Coleoptera), and roaches (Blatoidea). In comparisons based on the mass of a prey item relative to the mass of a lizard, Lerista had longer handling times for all prey categories and were limited to smaller prey than were Ctenotus. However, when comparisons were based on the length of prey relative to the length of a lizard's head, Lerista ate some elongate prey as fast or faster than did Ctenotus, and both genera successfully swallowed prey more than twice the length of their own head. Thus, the differences in prey-handling performance of Ctenotus and Lerista probably result from the fact that Lerista have a relatively shorter head than Ctenotus. All Lerista species, surface-dwelling and fossorial, have short heads compared to primitive sphenomorphine lizards. Fossorial species of Lerista have elongate trunks, and consequently their heads are shorter in proportion to trunk length than those of surface-dwelling Lerista. However, most fossorial species of Lerista are longer and heavier than any of their surface-dwelling congeners, and the heads of these fossorial species are large relative to the prey they encounter. As a consequence, the diets of large fossorial species of Lerista do not appear to be limited by their morphological specialization for sand-swimming.
穴居蜥蜴在形态上与其地表栖息的近亲不同。澳大利亚的楔齿蜥属Ctenotus由地表栖息物种组成，并且与Lerista属密切相关，Lerista属既包括地表栖息物种，也包括穴居物种。沙地游动代表了衍生状态，并且在Lerista的几个谱系中独立进化。这两个属的蜥蜴头部形状不同（Ctenotus的吻部钝圆，而Lerista的呈楔形），并且相对于身体的长度也不同（Ctenotus的头部约占吻肛长度的20%，而沙地游动的Lerista则为12%）。这些特化是否会影响Lerista能够捕食的猎物大小或类型呢？我们比较了Ctenotus和Lerista处理猎物的情况，以将形态差异与猎物处理能力的差异相关联，并区分吻部形状和头部长度的影响。喂食试验包括蜥蜴通常食用的三类昆虫猎物：软体幼虫（鳞翅目）、硬体幼虫（鞘翅目）和蟑螂（蜚蠊目）。在基于猎物质量相对于蜥蜴质量的比较中，Lerista对所有猎物类别的处理时间都更长，并且与Ctenotus相比，只能捕食更小的猎物。然而，当基于猎物长度相对于蜥蜴头部长度进行比较时，Lerista捕食一些细长猎物的速度与Ctenotus一样快或更快，并且两个属都成功吞下了长度超过其自身头部两倍的猎物。因此，Ctenotus和Lerista在猎物处理表现上的差异可能是因为Lerista的头部相对于Ctenotus相对较短。与原始楔齿蜥相比，所有Lerista物种，无论是地表栖息的还是穴居的，头部都较短。Lerista的穴居物种躯干细长，因此与地表栖息的Lerista相比，它们的头部相对于躯干长度更短。然而，大多数Lerista的穴居物种比它们任何地表栖息的同属物种都更长、更重，并且这些穴居物种的头部相对于它们遇到的猎物来说很大。因此，大型穴居Lerista物种的饮食似乎并没有受到它们沙地游动形态特化的限制。
