Biology subjects

Kumpitsch, L.

Publications and source records attributed to Kumpitsch, L..

3 recordsLinked to original sources

bioRxiv2026

Experimental evidence for antagonistic effects of sperm competition in two sea urchin species

Sperm competition can occur when sperm from two or more males compete for fertilization of a batch of eggs. While it has been extensively studied in internal fertilizers, it remains poorly under-stood in external fertilizers. To investigate how sperm competition affects fertilization under sperm limitation, we conducted controlled experiments on two sea urchin species: Paracentrotus lividus and Dendraster excentricus. Eggs from a single female were exposed to sperm from three individ-ual males separately (non-competitive treatment) or to a pooled sample from three males (competi-tive treatment). We measured fertilization success as proportion of eggs fertilized after two hours and assessed sperm motility as percentage of motile sperm and curvilinear velocity. For P. lividus , we estimated the sperm concentrations where fertilization success was 50% of maximum observed fertilization success (F50), and the fertilization efficiency of the sperm (Fe), i.e. the likelihood that a sperm - egg encounter results in a fertilizing contact, using the fertilization kinetics model of Styan (1998). For D. excentricus, fertilization success was measured at a sperm concentration expected to produce 50% fertilization success. Sperm competition reduced fertilization success and increased F50 compared to non-competitive treatments, suggesting antagonistic effects that may compromise fertilization under sperm-limited conditions in external fertilizers.

evolutionary biology↗

bioRxiv2026

Benchmarking Geometric Morphometric Methods: A Performance Evaluation for Gastropod Shell Shape Analyses

Understanding morphological variation is crucial for the study of speciation and for conservation as it helps in assessing biodiversity and predicting responses to environmental changes. These approaches are broadly applicable but are especially valuable in marine environments, where species are often elusive, difficult to study, and face heightened threats from rapid environmental shifts. The marine snail Littorina saxatilis is notable for its extensive polymorphism in shell shape, size, and colour, with ecotypes that evolve in response to environmental forces including wave exposure and crab predation. Morphometric tools have been central to investigating the mechanisms driving this phenotypic divergence; yet, a direct comparison of their methodological efficacy is lacking. Here, we took advantage of L. saxatilis ecotypes to contrast three morphometric approaches: elliptical Fourier analysis (EFA), landmarks-based geometric morphometrics (GM), and the growth-based model implemented in the ShellShaper software (SS). We assessed their clustering power, biological interpretability, robustness to measurement error and transferability among datasets. Our findings provide insights to guide method selection in studies aimed at exploring morphological variation: EFA is better suited for high-throughput screening and describing intermediate shapes; SS offers superior clustering power with highly interpretable growth parameters; and GM is best for detailed anatomical studies but is less efficient for large datasets. We provide guidelines to align method selection with specific research goals, balancing analytical efficiency with the required morphological and biological insight. By following this framework, researchers can ensure that robust morphological analysis is achieved, which is essential not only for elucidating mechanisms of adaptation and speciation but also for effective management and conservation of marine biodiversity.

evolutionary biology↗

bioRxiv2021

Mito-nuclear variation in transgenerational and reproductive effects of amino acid and lipid nutrition

Epistasis between mitochondrial and nuclear genomes can modulate fitness effects of nutrition. Are these "mitonuclear" effects deterministic with regard to optimal nutrition? Which nutrients and genetic loci participate? Here, in fruitflies, we show that mitonuclear epistasis repeatably dictates fitness effects of dietary lipids and amino acids, with a tripartite interaction emerging as an unprecedented source of quantitative variation. We also observed diet-dependent developmental lethality and parental effects, but only in specific mitonucleotypes. Associating phenotype to mtDNA variation implicated a non-coding RNA (mt:lrRNA), suggesting a novel mechanism, with epistasis between mitochondria-derived regulatory factors and the nuclear genome producing qualitative differences in how diet impacts fitness. SUMMARYCombined action of nuclear genotype and regulatory loci on mtDNA produces major differences in fitness impacts of nutrition.

genetics↗