Biology subjects

Koene, J. M.

Publications and source records attributed to Koene, J. M..

5 recordsLinked to original sources

bioRxiv2025

Differences in components of reproductive behaviour between populations at the simultaneously hermaphroditic snail Lymnaea stagnalis

Differences in reproductive behaviour can contribute to speciation by establishing reproductive isolation and can thus be a significant driving force in ecology and evolution. However, studies investigating intraspecific variation in reproductive behaviour remain scarce. In this study, we focused on a simultaneously hermaphroditic freshwater snail, Lymnaea stagnalis, a model organism whose reproductive behaviour is well documented, to examine behavioural differences among populations. In addition to a laboratory population, ten wild populations were sampled and standardised under laboratory conditions. Mating behaviour and egg production were quantified through observation experiments. The observed traits were analysed using a hierarchical Bayesian model to estimate the effects of each population on reproductive traits. Moreover, genetic information of the populations was estimated using low-coverage whole genome sequencing data, and phylogenetic signals for each trait were assessed. Our results revealed that populations exhibited distinct behavioural traits, and most prominent were the differences in male behaviours and the motivation to mate in the male role (after short and long sexual isolation). Egg production also clearly differed between populations. However, no phylogenetic signals were detected for any of the traits, suggesting that the diversification of behavioural traits among populations may result from evolutionary processes such as divergent selection or founder effects. This study highlights that reproductive behaviour can be highly diversified within a single species, and that assuming homogeneity in behaviour should be done with care.

ecology↗

bioRxiv2024

Herbivory can increase plant fitness via reduced interspecific competition. Evidence from models and mesocosms

Herbivores are generally considered to reduce plant fitness. However, as in natural communities herbivores often feed on several competing plant species, herbivores can also increase plant fitness by reducing interspecific competition among plants. In this study, we developed a testable model to predict plant fitness in the presence of an interspecific competitor and an herbivore that feeds on both plant species. Our model allows to predict at which herbivore and competitor densities the focal species will benefit from herbivory. This can be estimated by quantifying the effects of the herbivore on the fitness of the focal plant and on its competitor, and by estimating the levels of intra- and interspecific competition in a pair-wise fashion, respectively. We subsequently validated the model in indoor microcosms using three interacting species: an aquatic macrophyte (the giant duckweed Spirodela polyrhiza), its native competitors (green algae), and its native herbivore (the pond snail Lymnaea stagnalis). Additional outdoor mesocosm experiments supported our model under natural conditions. Together, this study provides a conceptual framework to understand how herbivores shape plant fitness in a community context.

ecology↗

bioRxiv2023

Sublethal heat reduces overall reproductive investment and male allocation in a simultaneously hermaphroditic snail species

A well-known effect of sub-lethal temperature exposure in a diversity of species is a decrease in reproductive performance. Although this effect has been particularly emphasized for males or male reproductive functioning, it remains to be firmly demonstrated that the effect of heat on fertility is sex-specific. To contribute to this question, here we examined the impact of sub-lethally high temperature on male and female functions in a simultaneously hermaphroditic snail species, Lymnaea stagnalis. Examining hermaphrodites is useful to evaluate the sex-specific impacts of heat exposure, since they possess male and female functions within a single individual, sharing genetic and environmental factors. Moreover, previously developed sex allocation theory allows us to compare the differential performance of sex functions. In this study, we exposed snails to temperatures ranging from 20 to 28 {degrees}C for 14 days and assessed their egg and sperm production, sperm transfer, mating behaviour and growth. Both types of gamete production were significantly reduced by higher temperature, leading to an overall reduction of reproductive investment. By quantifying sex allocation, we furthermore revealed that the heat-stressed snails reduced the relative investment in their male function. In addition, even though sperm production and its transfer were drastically decreased by high temperature, male mating motivation was not affected. This study illustrates that examining simultaneous hermaphrodites can provide significant insights for the impact of heat, and the proximate mechanism, on reproduction in wildlife.

ecology↗

bioRxiv2023

Dominant gingers: discovery and inheritance of a new shell polymorphism in the great pond snail Lymnaea stagnalis

Color polymorphism is a classic study system for evolutionary genetics. One of the most color-polymorphic animal taxa is mollusks, but the investigation for the genetic basis of color determination is often hindered by their life history and limited availability of genetic resources. Here we report on the discovery of shell color polymorphism in a much-used model species, the great pond snail Lymnaea stagnalis. While their shell is usually beige, some individuals from a Greek population show a distinct red shell color, which we nicknamed Ginger. Moreover, we found that the inheritance fits simple, single-locus Mendelian inheritance with dominance of the Ginger allele. We also compared crucial life history traits between Ginger and wild type individuals, and found no differences between morphs. We conclude that the relative simplicity of this polymorphism will provide new opportunities for a deeper understanding of the genetic basis of shell color polymorphism and its evolutionary origin.

genetics↗

bioRxiv2020

Identification, presence, and possible multifunctional regulatory role of invertebrate gonadotropin-releasing hormone/corazonin molecule in the great pond snail (Lymnaea stagnalis).

In the last years, the interpretation of gonadotropin-releasing hormone (GnRH) neuropeptide superfamily has changed tremendously. One main driver is the investigation of functions and evolutionary lineage of previously identified molluscan GnRH molecules. Emerging evidence suggests not only reproductive, but also diverse biological effects of these molecules and proposes they should most likely be called corazonin (CRZ). Clearly, a more global understanding necessitates further exploration of species-specific functions and structure of invGnRH/CRZ peptides. Towards this goal, we have identified the full-length cDNA of invGnRH/CRZ peptide in an invertebrate model species, the great pond snail Lymnaea stagnalis, termed ly-GnRH/CRZ, and characterized the transcript and peptide distribution in the central nervous system (CNS) and peripheral organs. Our results are consistent with previous data that molluscan GnRHs are more related to CRZs and serve diverse functions. For this, our findings support the notion that peptides originally termed molluscan GnRH are multifunctional modulators and that nomenclature change should be taken into consideration.

neuroscience↗