Assessing the temporal isolation barrier between two closely related species of the genus Fissurella off the southwestern coast of South America

ABSTRACT

Knowledge of the reproductive isolation mechanisms that prevent gene flow between species is essential for understanding the process of speciation. In this study, we investigate the spawning periods in Fissurella cumingi and F. latimarginata, two closely related sympatric species of keyhole limpets with external fertilization, as a potential prezygotic barrier between them. The reproductive cycle was assessed in two distinct locations in northern Chile using the gonadosomatic index (GSI) and gonadal histology. Species, locality, and sex were designated as predictive variables, while average GSI values, as well as those of partial and total spawning, were considered dependent variables. Both species exhibit a continuous gametogenic cycle throughout the year, characterized by multiple spawning events. A generalized linear model (GLM) factorial ANOVA design revealed that neither species, locality nor sex were significant factors with respect to the GSI and partial spawning scores. However, sex was found to be the only significant factor related to total spawning. No significant interactions were observed among predictive factors. These findings suggest that reproductive periods may not serve as effective barriers to gamete encounters between species. Our study prompts questions about how closely-related externally-fertilizing species maintain reproductive isolation.

KEYWORDS:

• Key-hole limpets
• reproduction
• reproductive isolation
• reproductive cycle
• spawning
• Chile

Acknowledgments

We thank René Durán for inviting us to participate in this research, and to Cristian Betancourt for helping with the sample collection. Additionally, I thank the anonymous referees for their valuable comments on the original manuscript.

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Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

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Funding

The author(s) reported there is no funding associated with the work featured in this article.