Molecular discrimination and phylogeographic patterns of clones of the parthenogenetic gecko Lepidodactylus lugubris in the Japanese Archipelago

Abstract

Vertebrates usually reproduce sexually in which males and females contribute their offspring genome and produce genetically diverse offspring. However, some of them are asexual without genetic contribution from males. The nocturnal gecko, Lepidodactylus lugubris, is all females and reproduces parthenogenetically. This gecko is known to consist of diploid and triploid clones in the tropical and subtropical regions, which can be identified by their dorsal marking patterns, ploidy, and protein polymorphism. This gecko is also distributed in the southern parts of Japan, and several clones have been reported. In this study, we investigated the origins and genetic diversity of Japanese L. lugubris by clonal discrimination using microsatellite and mitochondrial DNA analyses. A total of 748 individuals were collected from 21 islands of five island groups (Ogasawara, Okinawa, Miyako, Yaeyama and Daito Islands) and 17 clones were distinguished genetically. Mitochondrial cyt b sequences of these clones suggested that they were all closely related and differentiated recently. Clonal diversity was much higher (14 clones) in the Daito Islands than in the other island groups in which only one or two clones coexisted. Judging from the dorsal marking patterns and ploidy known so far, six clones were cosmopolitan and may be colonized from the outside of Japan. However, other 11 clones were endemic to the Daito Islands and explained by possible hybridization between the one female diploid clone and one male diploid clone because other 9 clones were triploid and all had the combinations of polymorphic microsatellite alleles of these female and male diploid clones. Although the males have never been recorded in the Daito Islands, males might appear in the past. These findings contribute to understanding of clonal diversity and dynamics of asexually reproducing animals. If diploid parthenogenetic geckos can produce triploid clones by mating with the diploid males, clonal diversity would increase rapidly in a small island, and such newly produced triploid clones would expand widely. K E Y W O R D S asexual reproduction, clonal diversity, hybridization, microsatellite analysis, ploidy change

Who’s your daddy? On the identity and distribution of the paternal hybrid ancestor of the parthenogenetic gecko Lepidodactylus lugubris (Reptilia: Squamata: Gekkonidae)

“…For example, L. moestus and L. pantai are both known from several of the small islands in the Caroline Islands and Palau Islands; therefore, these represent alternative potential locations of hybrid origin for additional L. lugubris clones (Buden & Taborosi 2016). Given the number of unique parthenogenetic lineages of L. lugubris (Ineich 1988;Ineich & Ota 1992;Yamashiro et al 2000), it is likely that hybridization of different bisexual parental ancestors gave rise to numerous diploid and triploid clones and some have subsequently been introduced elsewhere (Radtkey et al 1995;Ineich 1999;Ineich et al 2015), whereas others remain restricted to small original islets (Murakami & Hayashi 2019;Yamashiro et al 2000). In addition, backcrossing and/or potential hybridization with other species is likely to have occurred to produce multiple diploid and triploid clones (Saint Girons & Ineich 1992;Buden et al 2014;Trifonov et al 2015).…”

“…Backcrossing has been observed as well (Saint Girons & Ineich 1992;Buden et al 2014). The paternal lineage has generally been considered undescribed in subsequent literature (e.g., Zug 2013:106), and even in the most recent literature it is still referred to as "a yet undescribed Lepidodactylus species from the South Pacific" (Griffing et al 2019) or in other similar terms (e.g., Murakami & Hayashi 2019). Zug (2013:106) provided a more detailed morphological description of the unidentified paternal species and constrained its range to a similar area as proposed by Radtkey et al (1995).…”