Periodic Reporting for period 1 - FLORADAPT (Plant resilience and floral adaptation to pollinator change during a range expansion)
Période du rapport: 2016-09-01 au 2018-08-31
This is currently a very relevant question because evidence is accumulating of pollinator declines and, in consequence, plants are experiencing new “pollinator environments”. Concerns that this can in turn lead to declines in plant populations are growing, and that a negative loop in all interacting species can take place. Alternatively, some plants may be capable of rapid response to changes in their pollinators.
The general aim of FLORADAPT was to explore how plant populations respond to new pollinator environments by comparing native and invasive populations whose exposure to new pollinators has persisted in time for a few generations. For this, a team of students and I used the common foxglove (Digitalis purpurea) as a study system. Foxgloves are herbs native to Europe and pollinated by bumblebees, but have been introduced to all other continents. In tropical mountains, we expect that foxgloves flowers will be visited by a new set of potential pollinators. We used a combination of careful field measurements and genomic tools to study the resilience of the plants to the new pollination conditions. We were also interested in the evolutionary responses by the plant to having new pollinators.
Our main discoveries so far are as follows. Foxgloves in naturalised populations in South and Central America have incorporated new pollinators, including hummingbirds and several species of tropical bumblebees. In addition, flowers experience high levels of nectar robbing by specialised nectar robbers (Diglossa birds), bumblebees and hummingbirds. These new conditions allow foxlgoves to successfully repoduce, but lead to new selective pressures. As a consequence, we detect changes in corolla characteristics that are important because they allow or restrict access to the nectar reward offered to pollinators. The molecular analysis will corroborate if these changes we detect are heritable.
As human change the conditions for wild plants and animals, we are creating new evolutionary pressures. In some cases, like in our study, plants can be resilient. We will continue these studies to understand the genetic basis of this resilience, and to extend these studies to other wild plants.