Salvi Daniele
Department of Health, Life and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
Animals (Basel). 2023 Jul 13;13(14):2289. doi: 10.3390/ani13142289.
Among the extant populations of the critically endangered Aeolian wall lizard, the most vulnerable is the one surviving on La Canna, a columnar volcanic stack off the Filicudi Island. Here, I report the results of the first climbing expedition by a biologist on La Canna, that contributed direct observations and updated information on the size, morphology, and genetic variability of this population. Lizard density at the sampling site (a small terrace at 50 m of elevation) was 1.7 m, twice of a previous estimate. Standard methods for estimating population size are unsuitable for La Canna. An educated guess of about a hundred individuals can be drawn, considering the extent of habitat available on the stack and the number of observed lizards. Lizards on La Canna were not fearless, despite what was reported by alpinists, possibly because of aggressive intraspecific interactions or high environmental temperatures during sampling. Biometric data significantly extend the body size of La Canna's lizards and indicate that it is not smaller than other populations. A complete lack of genetic diversity was found at the mitochondrial gene, in line with previous allozyme data and with estimates on other microinsular populations. The small size of the La Canna population implies severe genetic drift and an extremely high level of inbreeding, as supported by low heterozygosity found across the genome. Detrimental effects of inbreeding depression are evident as cephalic malformations observed in all captured lizards of La Canna and might represent the more immediate threat to the persistence of this population.
在极度濒危的伊奥利亚壁蜥现存种群中，最脆弱的是在拉坎纳岛上存活的种群，拉坎纳岛是菲利库迪岛外的一座柱状火山岩。在此，我报告一位生物学家首次攀登拉坎纳岛的考察结果，此次考察提供了关于该种群规模、形态和遗传变异性的直接观测数据及最新信息。采样地点（海拔50米处的一个小平台）的蜥蜴密度为每平方米1.7只，是先前估计值的两倍。传统的种群规模估计方法不适用于拉坎纳岛。考虑到该岩岛上可用栖息地的范围以及观察到的蜥蜴数量，可以大致猜测该种群约有一百只个体。拉坎纳岛上的蜥蜴并非如登山者所报告的那样无所畏惧，这可能是由于种内攻击性互动或采样期间环境温度过高所致。生物特征数据显著扩展了拉坎纳岛蜥蜴的体型范围，并表明其体型并不小于其他种群。在线粒体基因方面发现完全缺乏遗传多样性，这与先前的等位酶数据以及对其他微型岛屿种群的估计结果一致。拉坎纳岛种群规模较小意味着严重的遗传漂变和极高的近亲繁殖水平，全基因组低杂合度也证实了这一点。近亲繁殖衰退的有害影响显而易见，在拉坎纳岛捕获的所有蜥蜴中均观察到头部畸形，这可能是该种群存续面临的最直接威胁。
