Project title: The evolution and conservation consequences of promiscuity in plants pollinated by vertebrates.
Dates: 2014 - 2016
Funding: Australian Research Council Discovery Scheme
Location: Perth, Albany, Wheatbelt
- plant mating
- pollen dispersal
- genetic diversity
- birds, insects
- banksias, eucalypts, kangaroo paws
This project addresses the generality and significance of intriguing new results suggesting that plants pollinated by highly mobile vertebrates (e.g. nectar-feeding birds) may be characterised by random mating and more extensive pollen pools than plants pollinated by animals exhibiting nearest-neighbour foraging movements. Thus, paternity of seeds is expected to extend to multiple plants far beyond near-neighbours around a mother plant, and as a consequence, plant populations should have higher levels of genetic diversity (and evolutionary potential) than mainstream theory would predict.
Our study is using molecular markers for the assignment of paternity to seed, as well as pollinator manipulations and observations, in multiple populations and species.
Our key objectives are to:
- Assign paternity to naturally pollinated seed in wild populations of three plant species (Eucalyptus caesia, Banksia ilicifolia and Anigozanthos manglesii) pollinated by nectar-feeding birds to assess patterns of mating and realized pollen dispersal. We hypothesise that pollination by nectar-feeding birds generally facilitates a departure from the nearest-neighbour pollination that is largely typical of insect and wind pollination, and that promiscuity, high multiple paternity and low correlated paternity of outcrosses are a feature of plants pollinated by these animals.
- Characterise local spatial genetic structure and variation. We hypothesise that pollination by nectar-feeding birds erodes spatial genetic structure and and maintains genetic diversity within plant populations.
- Manipulate access to flowers by birds, insects and mammals followed by paternity assignment of seed to characterise a pollen dispersal curve for each pollen vector. We hypothesise that pollination by insects (including introduced honeybees) and Honey Possums leads to predominantly nearest neighbour mating in species pollinated by highly mobile nectar feeding birds.
- Assess the fitness of progeny following pollination by birds versus mammals versus insects, as well as near-neighbour mating versus those of wide outcrossing through pollination manipulation and seedling growth experiments. We hypothesise that there is a fitness consequence from near-neighbour mating expressed as inbreeding depression, and that a departure from wide outcrossing and high multiple paternity for species typically pollinated by vertebrates has negative conservation implications.
- Conduct pollinator composition, abundance and movement observations, as well as measurements of plant phenology and density, to begin to address population factors that may impact on the generality of pollen flow distributions. Further, these observations will provide insight into the behaviours that lead to a departure from nearest neighbour mating. We hypothesise that composition of the pollinator community together with plant abundance and density will affect the distribution of pollen movement, but that general conclusions of a departure from nearest neighbour mating for nectar-feeding bird-pollinated plants are robust to this variation.
Dr Dave Roberts, Dr Siegy Krauss, Prof Stephen Hopper, Dr Ryan Phillips, Dr Janet Anthony
Nicole Bezemer (PhD; July 2015 - present) The evolutionary consequences of bird pollination for Eucalyptus caesia.
Bronwyn Ayre (PhD; March 2015 - present) Pollination by nectar feeding birds in kangaroo paws (Anigozanthos).