eLife (Inside eLife)

Adaptive Variation in Avian Eggshell Gas Conductance and Structure Across Elevational Gradients?

A new eLife study examined eggshell gas conductance and microstructure in 197 Andean bird species to test for adaptive variation across elevational gradients. Researchers measured water vapor conductance and used scanning electron microscopy, finding that conductance consistently declines at higher elevations. However, structural traits such as shell thickness, pore size, and pore density varied inconsistently among families, showing no universal pattern linked to altitude. The authors argue that these findings illuminate how embryonic water loss constraints may shape species’ elevational ranges and future climate‑change responses.