Implications of environmental changes for penis development in highly vulnerable phally polymorphic Vertigo species

In populations of phally polymorphic hermaphroditic species, two or three phallial morphs coexist, distinguished by the development of the penis. This study aimed to track changes in the frequency of these morphs over time and across sharp seasonal transitions in temperate climates, focusing on land snails. Additionally, it assessed whether shell dimensions differ among the phallial morphs. The study species were Vertigo moulinsiana (Dupuy, 1849) and Vertigo angustior Jeffreys, 1830, members of the Vertiginidae family, predominantly found in Europe. Both species are threatened with extinction and listed in Annex II of the EU Habitat Directive. According to the IUCN, V. angustior is classified as Near Threatened, and V. moulinsiana as Vulnerable. Findings reveal species-specific responses to seasonal changes. The proportions of phallial morphs varied over time, with euphallics consistently being a minority in both species. No significant differences in shell size were found among phallial morph types, although shell size varied significantly between seasons. This variability likely reflects local environmental conditions. The observed shifts in phallial morph frequency and shell size may influence the genetic diversity and reproductive traits in these species. These findings underscore the importance of further research, particularly in the context of climate change and habitat deterioration.