A decade-long analysis of bee activity in apple orchards in New York showed decreased pollination services in some orchards beyond what simple counts of bee number or species richness would predict. These pollination woes, authors of the related study say, are a result of millions of years of pollinator evolution being lost in these settings due to heavy agricultural activity - essentially, a "pruning" of the bee family tree there. Phylogenetic diversity, a measure of the evolutionary history and diversification represented within a community, can reveal similarities in the adaptive traits of organisms that share an environment, including traits that help mediate environmental change. However, historically, most conservation efforts don't account for this, focusing instead on simple measures of biodiversity. While it is generally understood that greater biodiversity, particularly trait diversity, begets healthy ecosystems, it remains unclear as to how and to what extent the losses of more closely or distantly related species affect their ability to provide ecosystem services, such as pollination. Heather Grab and colleagues looked at how agricultural activity altered phylogenetic diversity loss in pollinator communities in 27 apple orchards in New York state. Using a decade-long dataset of bee community and pollination observations as well as the genomic "bee tree of life," Grab et al. discovered that species loss due to agriculturally driven land use change had a great effect on pollinator phylogeny, driving the loss of millions of years of pollinator evolutionary history, and resulting in more closely related bee species, among those who remained. This created a negative impact on pollination - above and beyond what standard approaches would predict - and the result was smaller apple yield and poorer apple quality. The analysis suggests that phylogenetic diversity of the pollinator community could be a better gauge of pollinator services than bee abundance or species richness.
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Science