Alfons Weig | PubMed Health

PubMed2026

Quantifying niche overlap and transgression in allopolyploid hybrids: Case study of Sorbus subgenus Aria.

BACKGROUND AND AIMS: Apomixis, the formation of seeds without recombination, facilitates adaptation and persistence under environmental change. By preserving hybrid genotypes over long time periods, apomixis may conserve adaptive trait combinations from parental niche margins. We tested whether apomictic entities occupy intermediate, marginal, or transgressive niche space relative to their parents and whether differentiation is associated with ploidy. METHODS: We studied polyploid Sorbus subgenus Aria in the Franconian Jura (Germany), comprising two progenitors Sorbus aria and S. collina, seven triploid entities, and a pool of genetically heterogenous individuals (single genotypes). Genetic structure was assessed using MIG-seq. Overall niche differentiation between parental taxa and hybrids was evaluated using Sørensen similarity of two-dimensional hypervolumes derived from principal component analysis (PCA) axes. Niche shifts were further analyzed using hypervolumes based on the three strongest PCA variables. Across 762 occurrences, observations ranged from 11 to 453 individuals per entity. KEY RESULTS: Environmental niche space was transgressive in three, significantly allocated towards the margins of parental niche space in one, while remaining intermediate in the other entities. Niche transgression occurred towards milder temperatures and drier conditions. Genetic analyses confirmed morphologically defined entities, although one morphotype was polyphyletic. Tetraploid S. collina significantly occupied warmer and wetter environments compared to other cytotypes. Triploids differed from S. aria along microtopographic gradients represented by the second PCA axis. CONCLUSIONS: Apomictic Sorbus entities show diverse strategies in niche occupation and can occupy environmental niche space at and beyond the limits of their parental taxa. Apomicts may conserve evolutionary adaptations at the edges of parental niche space that may otherwise be lost from, or fail to emerge in, the parental gene pool. Over long timescales these trait combinations may re-enter the parental gene pool through introgression, thereby reintroducing adaptations critical for survival under changing conditions.

Aria↗

PubMed2026

Parental niche construction buffers microbial and competitive challenges and drives offspring dependence in burying beetles.

Parents across diverse taxa modify the biotic or abiotic environments of their offspring. Such modifications may constitute ecological inheritance and are central to developmental niche construction, whereby organisms shape developmental conditions and selective pressures experienced by the next generation. Despite its theoretical importance, parental niche construction is often studied under simplified conditions or by focusing on single components of care, limiting our understanding of how multiple parental modifications interact in ecologically relevant contexts, whether they buffer environmental heterogeneity, and how this shapes offspring development and evolutionary trajectories. Using the burying beetle Nicrophorus vespilloides, we investigated how parents jointly modify chemical and microbial properties of vertebrate carcasses, a highly contested resource on which offspring develop. We show that under natural microbial and competitive conditions, prehatch care enhances larval survival and growth, alters cadaveric volatile emissions, and reduces carcass attractiveness to competitors. While soil type shapes carcass-associated microbial communities, parental care buffers these environmental effects, creating a more consistent microbiome and reducing environmentally induced larval mortality. Larvae of the related species Ptomascopus morio, which lacks prehatch carcass preparation, survived equally well on prepared and unmodified carcasses, whereas N. vespilloides larvae showed reduced survival on unmodified carcasses. This contrast is consistent with the hypothesis that N. vespilloides larvae have evolved a reliance on a parentally constructed developmental environment. Together, these findings show that parental care can constitute an integrated form of niche construction that reshapes developmental environments, enhances offspring performance, and may promote evolutionary feedback leading to increased offspring dependence on parental care.

Animals↗