Project-Our Winter Playground: Manzanita, Climate Change, and Schizoid Floral Visitors

Pollination of manzanita (Arctostaphylos pungens) by Osmia ribifloris on Mount Lemmon near Tucson. Manzanita flowers in this area are heavily robbed by mysterious nectar thieves. Photo: Dorit  Eliyahu.
Pollination of manzanita (Arctostaphylos pungens) by Osmia ribifloris on Mount Lemmon near Tucson. Manzanita flowers in this area are heavily robbed by mysterious nectar thieves. Photo: Dorit Eliyahu.

The first shrub to flower every year at mid-elevations in southern Arizona’s Sky Islands is pointleaf manzanita, Arctostaphylos pungens. Flowering generally begins in late January. However, it’s clear from long-term data that, like many plants at the same elevations in the Southwest, it has been undergoing a progressive shift to later flowering – very different from what’s being seen in temperate plant communities worldwide! NIH-funded postdoc Nicole Rafferty has been studying the reproductive consequences of this shift for manzanita; grad student Paul CaraDonna has been looking at the extent to which phenology of Osmia ribifloris bees, which appear to be heavily dependent upon manzanita, match up with it. Meanwhile, many others in the lab – including postdocs, grad students, and their undergraduate assistants – have focused their attention on the large community of insects that visit manzanita flowers (Richardson and Bronstein 2012). Similar to the bees at RMBL (see above), almost all the floral visitors are mixing mutualistic and exploitative feeding strategies. Observational and experimental studies by NIH-funded postdoc Jessie Barker, grad students Sarah Richman and Gordon Smith, and research scientist Dorit Eliyahu are trying to determine why individual insect species follow the strategies that they do; postdoc Chris Johnson is comparing the structure of visitor communities across different Sky Islands in southern Arizona. With our lovely site only a half-hour drive from our lab, manzanita offers a wonderful spring-semester playground for both major and minor projects by postdocs, grad students, undergrads, and lab visitors.