Guwahati: In a remarkable finding, researchers in Mizoram have identified male individuals in a gecko species previously thought to consist entirely of females.
The team, led by Krijoboti Thaosen, Jayaditya Purkayastha, Mathipi Vabeiryureilai, and Hmar T. Lalremsanga, uncovered the presence of functional males in Hemidactylus garnotii, a gecko species known for reproducing via parthenogenesis—a process where females produce offspring without fertilization. The study was published in the journal Taprobanica.
This discovery was made during fieldwork in the dense forests of Dampa Tiger Reserve and the tranquil surroundings of Palak National Wetland in Mizoram. The species, which has long been studied for its ability to thrive without males, had always been considered a prime example of obligate parthenogenesis. For decades, sporadic reports of potential males in this species were dismissed as misidentifications. However, the Mizoram study has changed this narrative entirely.
The research team conducted detailed morphological examinations, histological analysis, and genetic sequencing of the specimens collected. Their findings were conclusive: the male geckos possess fully functional reproductive systems, including active spermatogenesis, and belong to the same genetic lineage as the females. This breakthrough raises significant questions about the reproductive biology and evolutionary history of the species.
The implications of this discovery extend beyond Hemidactylus garnotii. It challenges the assumption that parthenogenetic species are strictly unisexual. The presence of males in a species known for reproducing clonally suggests a potential for genetic diversity and a previously unrecognized flexibility in its reproductive strategy. This could provide the species with an evolutionary advantage, particularly in changing environments where genetic variation might enhance adaptability.
Histological studies conducted by the team showed that the males exhibit distinct stages of spermatogenesis. These include spermatogonia, primary and secondary spermatocytes, spermatids, and mature spermatozoa. The presence of these stages confirms the functional fertility of the males. Morphologically, the males were found to have distinct features such as femoral pores and hemipenial bulges, which further distinguish them from the females.
Genetic analysis revealed that the Mizoram population of Hemidactylus garnotii shares a close relationship with populations in Myanmar. This finding opens up new avenues for research, particularly in understanding the evolutionary origins of the species. Could the males represent a remnant of an ancestral sexual lineage? Or might they indicate an adaptive response to environmental pressures?
The discovery also highlights the richness of Mizoram’s biodiversity. Nestled in the northeastern region of India, the state is home to an array of unique species and ecosystems. The forests of Dampa Tiger Reserve and the wetlands of Palak serve as critical habitats, providing refuge to numerous endemic and lesser-known species.
While the discovery is a milestone, it also underscores the need for further research. Scientists are now keen to investigate whether the males of Hemidactylus garnotii actively contribute to reproduction in natural settings. Are they merely an evolutionary relic, or do they play a significant role in the species’ survival? Additionally, the absence of genetic data from the species’ type locality in French Polynesia leaves room for further exploration.
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