Grismer L Lee, Wood Perry L, Le Minh Duc, Quah Evan S H, Grismer Jesse L
Herpetology Laboratory Department of Biology La Sierra University Riverside CA USA.
Department of Biological Sciences & Museum of Natural History Auburn University Auburn AL USA.
Ecol Evol. 2020 Nov 22;10(24):13717-13730. doi: 10.1002/ece3.6961. eCollection 2020 Dec.
Understanding the processes that underpin adaptive evolutionary shifts within major taxonomic groups has long been a research directive among many evolutionary biologists. Such phenomena are best studied in large monophyletic groups that occupy a broad range of habitats where repeated exposure to novel ecological opportunities has happened independently over time in different lineages. The gekkonid genus is just such a lineage with approximately 300 species that range from South Asia to Melanesia and occupy a vast array of habitats. Ancestral state reconstructions using a stochastic character mapping analysis of nine different habitat preferences were employed across a phylogeny composed of 76% of the known species of . This was done in order to ascertain which habitat preference is the ancestral condition and from that condition, the transition frequency to more derived habitat preferences. The results indicate that a general habitat preference is the ancestral condition for and the frequency of transitioning from a general habitat preference to anything more specialized occurs approximately four times more often than the reverse. Species showing extreme morphological and/or ecological specializations generally do not give rise to species bearing other habitat preferences. The evolution of different habitat preferences is generally restricted to clades that tend to occur in specific geographic regions. The largest radiations in the genus occur in rocky habitats (granite and karst), indicating that the transition from a general habitat preference to a granite or karst-dwelling life style may be ecologically uncomplicated. Two large, unrelated clades of karst-associated species are centered in northern Indochina and the largest clade of granite-associated species occurs on the Thai-Malay Peninsula. Smaller, independent radiations of clades bearing other habitat preferences occur throughout the tree and across the broad distribution of the genus. With the exception of a general habitat preference, the data show that karst-associated species far out-number all others (29.6% vs. 0.4%-10.2%, respectively) and the common reference to karstic regions as "imperiled arcs of biodiversity" is not only misleading but potentially dangerous. Karstic regions are not simply refugia harboring the remnants of local biodiversity but are foci of speciation that to generate the most speciose, independent, radiations across the genus. Unfortunately, karstic landscapes are some of the most imperiled and least protected habitats on the planet and these data continue to underscore the urgent need for their conservation.
长期以来，了解主要分类群内适应性进化转变背后的过程一直是许多进化生物学家的研究方向。此类现象最好在大型单系群中进行研究，这些单系群占据广泛的栖息地，随着时间的推移，不同谱系在这些栖息地中独立地反复面临新的生态机遇。壁虎属就是这样一个谱系，大约有300个物种，分布范围从南亚到美拉尼西亚，占据了各种各样的栖息地。利用对九种不同栖息地偏好的随机特征映射分析进行祖先状态重建，该分析覆盖了由该属76%的已知物种组成的系统发育树。这样做是为了确定哪种栖息地偏好是祖先状态，并从该状态确定向更衍生的栖息地偏好的转变频率。结果表明，一般的栖息地偏好是该属的祖先状态，从一般栖息地偏好向任何更特殊的偏好转变的频率大约是反向转变的四倍。表现出极端形态和/或生态特化的物种通常不会产生具有其他栖息地偏好的物种。不同栖息地偏好的进化通常局限于倾向于出现在特定地理区域的分支。该属最大的辐射发生在岩石栖息地（花岗岩和喀斯特），这表明从一般栖息地偏好向花岗岩或喀斯特栖息生活方式的转变在生态上可能并不复杂。两个与喀斯特相关的大型、不相关的物种分支集中在印度支那北部，与花岗岩相关的最大物种分支出现在泰国-马来西亚半岛。具有其他栖息地偏好的较小的独立分支辐射出现在整个系统发育树以及该属的广泛分布区域。除了一般的栖息地偏好外，数据显示与喀斯特相关的物种数量远远超过所有其他物种（分别为29.6%和0.4%-10.2%），将喀斯特地区普遍称为“生物多样性受威胁弧”不仅具有误导性，而且可能是危险的。喀斯特地区不仅仅是容纳当地生物多样性残余的避难所，而是物种形成的焦点，能够在整个属中产生最多样化、独立的辐射。不幸的是，喀斯特地貌是地球上一些受威胁最严重且保护最少的栖息地，这些数据继续强调了对其进行保护的迫切需求。
