Biology subjects

Tielboerger, K.

Publications and source records attributed to Tielboerger, K..

3 recordsLinked to original sources

bioRxiv2025

Plastic germination, temporal niche partitioning, and emergent assortative mating in annual plants

Temporal fluctuations in environmental conditions can promote coexistence via the storage effect, which requires a mechanism buffering different variants during adverse periods. This mechanism readily occurs in annual plants whose seeds do not necessarily germinate each year but instead remain dormant in a seed bank. Yet, how plasticity in germination timing affects genetic diversification and ecological speciation under temporally varying conditions remains poorly understood. Here, we use mathematical modeling and individual-based simulations to investigate the joint evolution of a combination of traits controlling plastic seed germination and plant fecundity under interannual environmental fluctuations. We show that adaptive plasticity in germination readily evolves via a genetic association between seed and plant traits, allowing seeds to germinate preferentially in years favorable for their subsequent growth and reproduction. Such adaptive plasticity enhances the storage effect and promotes genetic divergence among different morphs specialized to distinct yearly conditions. Because these morphs germinate preferentially in different years, plastic germination indirectly generates temporal assortative mating, thereby maintaining genetic associations among seed and plant traits despite the absence of physical linkage between loci controlling these traits. This temporal assortative mating ultimately leads to reproductive isolation between morphs, thus laying the foundation for ecological speciation. Our findings show that adaptive plasticity and genetic diversification are not mutually exclusive but can interact synergistically to enhance biodiversity.

evolutionary biology↗

bioRxiv2024

Environmental versus litter traits as drivers of microbial decomposer functions

Plant litter decomposition is a key ecosystem process with significant implications for global carbon cycling, soil fertility and plant productivity. Given that microbial decomposers are the main players in the decomposition process, it is surprising how little is known about their functional diversity in different habitats or their ability to respond to environmental changes. To fill this knowledge gap, we conducted a litterbag decomposition experiment along a pronounced climate and vegetation gradient in the Chilean Coastal Cordillera (26{degrees}S to 38{degrees}S), ranging from hyper-arid to temperate, using mixtures of four plant species, native to the respective ecosystems. We analyzed potential decomposition functions of bacterial and fungal litter communities along with their biotic (litter traits) and abiotic (meteorological conditions and soil properties) environments, to determine the relative importance of these environmental factors for microbial community functioning. We also tested the impact of the functional diversity of the decomposer communities (i.e., the diversity of decomposition related functions) on litter mass loss. Functional composition was related most strongly to the temporal variation of precipitation and radiation, explaining about 19 % and 6 % of variation in bacteria and fungi, respectively. In contrast, functional diversity was quite strongly related to litter chemical traits (C:N, C:P, tannins, phenols). Litter mass loss after six months of decomposition was not correlated to the functional diversity of decomposer communities but increased with the presence of habitat generalists like Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes. Taken together, these results highlight i) the interplay between abiotic factors and chemical litter traits on litter microbial functions and functional diversity and ii) the importance of microbial generalists for litter decomposition across different ecosystems. These results enhance our ability to predict changes in microbial decomposer communities and litter decomposition under future climate-change scenarios.

ecology↗

bioRxiv2018

Whole plant community transplants across climates reveal total community stability due to large shifts in species assemblage

(1) Climate change will decrease precipitation and increase rainfall variability in Eastern Mediterranean regions, with responses of plant communities largely uncertain. Here, we tested short-term responses of dryland plant communities to contrasting rainfall regimes using a novel experimental approach. (2) We exposed three annual plant communities to sharp changes in climatic conditions using whole community reciprocal transplants of soil and seed banks. We tested for the role of climate vs. community origin on community response and resistance. In parallel, we asked whether origin-specific climatic adaptations predict compositional shifts across climates. (3) For both community origins, the most dry-adapted species in each community increased in dry climate and the wet-adapted species increased in wet climate. Dry community origins showed large compositional shifts while maintaining stable plant density, biomass and species richness across climates. Conversely, wet communities showed smaller compositional shifts, but larger variation in biomass and richness. (4) Asynchrony in species abundances in response to rainfall variability could maintain structural community stability. This, in combination with seed dormancy, has the ability to delay extinction in response to climate change. However, increasing occurrence of extreme droughts may, in the long-term, lead to loss of wet-adapted species.

ecology↗