Abstract
Caves constitute ideal study systems for investigating adaptation and speciation, as the abiotic conditions shared by aphotic habitats exert a set of environmental filters on their communities. Arachnids constitute an important component of many cave ecosystems worldwide. We investigated the population genomics of two whip spider species: Sarax ioanniticus, a widely distributed parthenogenetic species found across the eastern Mediterranean; and S. israelensis, a recently described troglomorphic species that is endemic to caves in Israel. Here, we show that S. israelensis is completely genetically distinct from S. ioanniticus and most likely also a parthenogen. Counterintuitively, despite the lack of genetic variability within S. ioanniticus and S. israelensis, we discovered considerable variation in the degree of median eye reduction, particularly in the latter species. Natural history data from captive-bred specimens of S. israelensis validated the interpretation of parthenogenesis. Our results are most consistent with a scenario of a sexual ancestral species that underwent speciation, followed by independent transitions to apomictic parthenogenesis in each of the two daughter species. Moreover, the lack of genetic variability suggests that variation in eye morphology in S. israelensis is driven exclusively by epigenetic mechanisms.
Original language | American English |
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Article number | 107560 |
Journal | Molecular Phylogenetics and Evolution |
Volume | 175 |
DOIs | |
State | Published - Oct 2022 |
Bibliographical note
Funding Information:We thank A. Frumkin, B. Langford, E. Cohen (Israel Cave Research Center), and E. Levin for assistance with cave data and in the field. Sequencing was performed at the UW-Madison Biotechnology Center. Access to computing was provided by the Bioinformatics Resource Center (BRC) of the University of Wisconsin-Madison. Fieldwork in Israel was supported by a National Geographic Society Expeditions Council grant no. NGS-271R-18 to J.A.B.. This work is supported by the US-Israel Binational Science Foundation grant no. BSF-2019216 to P.P.S. and E.G.-R. This manuscript was improved by valuable comments from the associate editor Mike Rix, and from Miquel Arnedo and one anonymous reviewer.
Funding Information:
Specimens of Amblypygi were collected under permits 2013/40027, 2013/40085, 2014/40313, 2017/41718 and 2020/42450, issued to E.G.-R.; and permits 2012/38653, 2013/40027, 2014/40313, 2014/40503 and 2016/41370, issued to G.W. by the Israel National Parks Authority. We thank A. Frumkin, B. Langford, E. Cohen (Israel Cave Research Center), and E. Levin for assistance with cave data and in the field. Sequencing was performed at the UW-Madison Biotechnology Center. Access to computing was provided by the Bioinformatics Resource Center (BRC) of the University of Wisconsin-Madison. Fieldwork in Israel was supported by a National Geographic Society Expeditions Council grant no. NGS-271R-18 to J.A.B. This work is supported by the US-Israel Binational Science Foundation grant no. BSF-2019216 to P.P.S. and E.G.-R. This manuscript was improved by valuable comments from the associate editor Mike Rix, and from Miquel Arnedo and one anonymous reviewer.
Publisher Copyright:
© 2022 Elsevier Inc.
Keywords
- Genotyping-by-sequencing
- Molecular clock
- Population genomics
- Sarax
- Sympatry
- Troglophile