Animals : an Open Access Journal from MDPI · 4 authors, 2 centres
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This observational field study on wild Asian short-toed lark nestlings found that lower food availability (grasshopper nymph biomass) was associated with higher expression of immune cytokine genes (IFN-γ, TNF-α, IL-1β) and lower plasma IGF-1 and body mass, suggesting physiological plasticity. A key limitation is the correlational nature of the field data, which cannot establish causation or long-term fitness consequences.
This study investigated how wild Asian short-toed lark nestlings physiologically respond to varying food abundance, a scenario relevant to climate change-induced trophic mismatch. The background highlights that climate change can desynchronize bird breeding from insect prey peaks, potentially challenging nestling survival. The researchers measured the relative abundance of grasshopper nymphs (nymph biomass proportion, NBP) in the field and collected blood samples from 135 four-day-old nestlings to analyze immune cytokine gene expression (IFN-γ, TNF-α, IL-1β) via RT-qPCR, plasma IGF-1 via immunoassay, body mass, and fledging rates. Cytokine expression was negatively correlated with IGF-1. The study's limitations include its observational design, which cannot prove causation, and the focus on short-term physiological indicators without data on long-term adult fitness. The authors conclude this immunity-growth plasticity may help nestlings temporarily buffer poor food conditions, but its effectiveness during severe or prolonged mismatches is uncertain.
