Evolution of reproductive strategies in the species-rich land snail subfamily Phaedusinae (Stylommatophora: Clausiliidae)

Most of the present knowledge on animal reproductive mode evolution, and possible factors driving transitions between oviparity and viviparity is based on studies on vertebrates. The species rich door snail (Clausiliidae) subfamily Phaedusinae represents a suitable and unique model for further examining parity evolution, as three different strategies, oviparity, viviparity, and the intermediate mode of embryo-retention, occur in this group. The present study reconstructs the evolution of reproductive strategies in Phaedusinae based on time-calibrated molecular phylogenetics, reproductive mode examinations and ancestral state reconstruction. Our phylogenetic analysis employing multiple mitochondrial and nuclear markers identified a well-supported clade (including the tribes Phaedusini and Serrulinini) that contains species exhibiting various reproductive strategies. This clade evolved from an oviparous most recent common ancestor according to our reconstruction. All non-oviparous taxa are confined to a highly supported subclade, coinciding with the tribe Phaedusini. Both oviparity and viviparity occur frequently in different lineages of this subclade that are not closely related. During Phaedusini diversification, multiple transitions in reproductive strategy must have taken place, which could have been promoted by a high fitness of embryo-retaining species. The evolutionary success of this group might result from the maintenance of various strategies.© 2021 The Authors. Published by Elsevier Inc. This is an open access article published under a Creative Commons licence https://creativecommons.org/licenses/by/4.0/

The evolution of reproductive strategies in invertebrates - viviparity and egg retention

Żyworodność oraz przetrzymywanie rozwijających się jaj w macicy, lub innej wyspecjalizowanej komorze lęgowej, są rozprzestrzenione u bezkręgowców i wyewoluowały niezależnie w wielu grupach taksonomicznych. Strategie te wiążą się ze zróżnicowanymi sposobami dostarczania pożywienia dla rozwijających się młodych (lecytotrofia, matrotrofia lub adelfofagia), jak również szeregiem przystosowań anatomicznych i morfologicznych, które zwiększają wprawdzie przeżywalność młodych, ale mogą obniżać płodność rodzica. Ewolucyjny kompromis pomiędzy liczbą młodych w miocie a ich wielkością, która określa inwestycję rodzica w pojedynczy organizm potomny, wynika z ograniczonej objętości komór inkubacyjnych. U bezkręgowców związek pomiędzy czynnikami siedliskowymi a powstaniem żyworodności nie jest dobrze poznany, ale strategia ta jest bardziej powszechna w niektórych środowiskach np. u gatunków z mórz polarnych (szkarłupnie, małże) i wód słodkich (ślimaki, małże). Natomiast wśród owadów żyworodność obserwowano równolegle z koprofagią, pasożytnictwem lub malakofagią stadiów larwalnych, a także hematofagią lub myrmekofilią imagines.Viviparity and short retention of developing eggs in uterus or other specialised brood chambers are widespread in invertebrate taxa and evolved many times independently. Strategy of brood protection involves different mechanisms of providing nourishment for developing embryos (lecithotrophy, matrotrophy or adelphophagy), as well as the array of anatomical and morphological adjustment. Brood protection increases offspring survival, but may reduce maternal fecundity. Evolutionary trade-off between fecundity of viviparous and egg retaining animals and the parental investment per offspring depends on the limited space of incubatory structures. Ecological correlates of parental care in invertebrates are still under debate but brood protecting species are more common in polar seas (Echinodermata, Bivalvia) and freshwater habitats (Gastropoda, Bivalvia). Among insects viviparity is frequently associated with coprophagy, parasitism or malacophagy of larvae and hematophagy or myrmekophily of imagines

INFLUENCE OF HABITAT STRUCTURE AND CONDITIONS IN FLOODPLAIN FORESTS ON MOLLUSC ASSEMBLAGES

Alder floodplain forests are a rare and threatened forest type in Europe. These forests can be very rich in mollusc species. The intermediate disturbance hypothesis predicts that species richness should peak at intermediate inundation frequency, that is, at intermediate elevation above the river level. We additionally hypothesized that constantly high soil moisture can distort the usually positive correlation between the amounts of downed deadwood and snail richness, and that tree stems might be more favourable than deadwood because their vertical structure provides a better refuge during inundation events. To this end, we sampled molluscs from a core area of 20 x 20 m from eight alluvial forests with black alder in the surroundings of Lodz, Central Poland. In each core area, substrate was collected from eight random plots (0.25 m(2) each). We also recorded soil pH, vascular plant species and mosses diversity, along with other structural variables. Plant indicator values were calculated according to Ellenberg. Soil quality (amongst others: soil pH, reactivity value, nutrient and moisture availability) decreased with increasing elevation above the river level. In the plot samples, we found a total of 18,497 individuals from 52 species. Mollusc species richness dropped stronger than densities with an increasing elevation above the river level Main influences on mollusc richness and abundance originated from positive correlations with soil pH and moisture. An additional hand sampling campaign on tree stems and deadwood items in the core area revealed that coarse woody debris items on average carried twice as many individuals as did tree stems. Deadwood and tree stems supported similar numbers of snail species per item, but beta-diversity was higher on deadwood. Consequently, Jackknife 2 predicted that deadwood is utilized by about 46 species, whereas tree stems only support about 39 species. Our results indicate (1) that mollusc richness peaks at low elevations above normal water level in this type of forest, (2) that intact hydrological regimes are associated with high soil quality and mollusc biodiversity, and (3) suggest that coarse woody debris adds resources, refuges and a dispersal agent for the alder forest floor fauna

Filling the gaps in ecology of tropical tiger beetles (Coleoptera: Cicindelidae): first quantitative data of sexual dimorphism in semi-arboreal Therates from the Philippine biodiversity hotspot

Background Sexual dimorphism, driven by sexual selection, leads to varied morphological distinctions in male and female insects, providing insights into selection pressures across species. However, research on the morphometric variability within specific taxa of tiger beetles (Coleoptera: Cicindelidae), particularly arboreal and semi-arboreal species, remains very limited. Methods We investigate sexual dimorphism in six semi-arboreal Therates tiger beetle taxa from the Philippines, focusing on morphological traits. We employed morphometric measurements and multivariate analyses to reveal patterns of sexual dimorphism between sexes within the taxa. Results Our results indicate significant sexual dimorphism in elytra width, with females consistently displaying broader elytra, potentially enhancing fecundity. Notable sexual size dimorphism was observed in Therates fulvipennis bidentatus and T. coracinus coracinus, suggesting heightened sexual selection pressures on male body size. Ecological factors, mating behavior, and female mate choice might contribute to the observed morphological variation. These findings emphasize the need for further studies to comprehend mating dynamics, mate choice, and ecological influences on morphological variations in semi-arboreal and arboreal tiger beetles

The phylogenetic position of Synprosphyma A.J. Wagner, 1920 within Clausiliidae:biogeographic and taxonomic implications

Molecular phylogenetic studies have provided new insights into the relationships within the highly speciose clausiliid subfamily Phaedusinae, but they have also triggered new questions about the position of Synprosphyma A.J. Wagner 1920 within that subfamily. This study shows that Synprosphyma constitutes a c. 37.3 million-year-old lineage within Clausiliidae, which is neither closely connected with the remaining Phaedusinae nor with any other clausiliid taxon. Synprosphyma is therefore placed in a separate subfamily, Synprosphyminae. It constitutes a third eastern Eurasian lineage of Clausiliidae, next to Garnieriinae and the redefined Phaedusinae. Our phylogeographic analysis points to a larger role of eastern Eurasia in the biogeographic history of Clausiliidae than previously assumed; however, it is not yet resolved whether this was as part of a wide ancestral Eurasian range of Clausiliidae or as an area that was repeatedly colonized from western Eurasia. The distributional pattern of Phaedusinae, Synprosphyminae, and Garnieriinae in Eurasia is similar to that of relict floras, which suggests similar climatic preferences coupled with a comparable role of historical range contractions and/or passive dispersal

Giants of Taiwan – Comparative Analysis of Life History Traits in Four Land Snail Species Changphaedusa horikawai, Formosana swinhoei, F. formosensis, and Formosana sp. (Stylommatophora: Clausiliidae: Phaedusinae)

Family Clausiliidae (door-snails), which includes oviparous, embryo-retaining and viviparous species, can be a model group for studies on the evolution of reproductive modes in land snails. Yet, for understanding of evolutionary drivers leading to repeated changes of reproductive strategy, the identification of life history traits in phylogenetic lineages and geographical regions is fundamental. In this paper, we identified reproductive modes of clausiliid species endemic to Taiwan: Changphaedusa horikawai, Formosana formosensis, F. swinhoei, and an undescribed new species Formosana sp. Observations were conducted under laboratory conditions. Among Formosana species, oviparity predominated but embryo-retention was also recorded. The size of eggs and egg clutches differed between studied taxa. In contrast, C. horikawai was viviparous and delivered neonates. Anatomical examination of the fresh material allowed for unique observation of a large podocyst in embryos kept in the genital tract. This flattened structure may enable respiration or nutrient transfer between an embryo and a parent. In the regularly sampled wild population from Dawulun (N. Taiwan), gravid individuals were collected between April and November. The number of embryos reached three to nine per gravid individual. None of the species reproduced by self-fertilisation. Results of our study may support implementing conservation measures for malacofauna of Taiwan

Evolution of reproductive strategies in the species-rich land snail subfamily Phaedusinae (Stylommatophora: Clausiliidae)

Most of the present knowledge on animal reproductive mode evolution, and possible factors driving transitions between oviparity and viviparity is based on studies on vertebrates. The species rich door snail (Clausiliidae) subfamily Phaedusinae represents a suitable and unique model for further examining parity evolution, as three different strategies, oviparity, viviparity, and the intermediate mode of embryo-retention, occur in this group. The present study reconstructs the evolution of reproductive strategies in Phaedusinae based on time-calibrated molecular phylogenetics, reproductive mode examinations and ancestral state reconstruction. Our phylogenetic analysis employing multiple mitochondrial and nuclear markers identified a well-supported clade (including the tribes Phaedusini and Serrulinini) that contains species exhibiting various reproductive strategies. This clade evolved from an oviparous most recent common ancestor according to our reconstruction. All non-oviparous taxa are confined to a highly supported subclade, coinciding with the tribe Phaedusini. Both oviparity and viviparity occur frequently in different lineages of this subclade that are not closely related. During Phaedusini diversification, multiple transitions in reproductive strategy must have taken place, which could have been promoted by a high fitness of embryo-retaining species. The evolutionary success of this group might result from the maintenance of various strategies