Pollinator decline, high pollen limitation and low progeny quality

Interactions between species are especially sensitive to environmental changes. The interaction between plants and pollinators is of particular interest given the potential current global decline in pollinators. Reduced pollinator services can be compensated for in some plant species by self-pollination. However, if inbreeding depression is high, selfed progeny could die prior to reaching adulthood, leading to cryptic recruitment failure.

Van Etten et al. examine pollinator abundance, pollen limitation, selfing rates and inbreeding depression in populations with varying disturbance in Sophora microphylla, an endemic New Zealand tree species, and find that populations with fewer pollinators have lower offspring quantity and, more generally, low offspring quality. Over half the seeds produced are genetically doomed, which could lead to cryptic recruitment failure, i.e. a decline in successful reproduction despite high progeny production. The results highlight the importance of considering both offspring quantity and quality when predicting species’ response to global pollinator declines.