An examination of the spatial dimensions of pollination facilitation in an arid ecosystem.
Jenna BraunThesis Proposal – 1st Committee Meeting November 16 2016
Positive Interactions
Pollination Facilitation
Mechanisms
Increased size of co-flowering display
Increased diversity of floral display
Pollinator support: Sequential Mutualism/Community Stability
Magnet species
Magnet Hypothesis
Presence of a more attractive species increases pollination of a less attractive species or to a mixed assembly of species
Predicts that the effect is greater than only increasing floral abundance
Shrubs and cacti as magnets
ScaleGrain – size of the sampling unit. Can be pixel, focal plant, plot, patch.Extent – total area over which sampling occurs.
Data vs. model
Do individual interactions matter at larger scales?
What is the effect of a magnet species on its neighbours? Neighborhood? Patch? Landscape?
Landscape
Neighborhood
Plot
Plant
A systematic review contrasting pollinator facilitation in desert shrubs and cacti.
Determine support for current hypotheses and identify any research gaps.
Is current literature is reporting scale in a meaningful, replicable way?
CH1
Hypothesis:
Pollinator facilitation neglects scale but the spatial component of plant-pollinator interactions is an important research gap.
CH1
Figure 1: PRISMA diagram (Moher et al, 2009) of workflow for pollination facilitation systematic review.
Papers obtained through database searching (Web of Science), Keywords: Pollinat* facilitat* shrub Pollinat* facilitat* cact* Pollinat* competit* shrub Pollinat* competit* cact*
(n = 169)
Scre
enin
g In
clud
ed
Elig
ibili
ty
Iden
tifica
tion
Papers obtained from other sources, such as book chapter bibliographies
Records after duplicates removed (n = 169)
Records screened by abstract (n = )
Records excluded for: Relevance
Review, opinion or idea paper
Full-text articles assessed for eligibility
(n = )
Full-text articles excluded:
Not testing facilitation or competition (n = )
Not testing interspecific interactions (n = )
Focal species wind-pollinated
Include in synthesis (n = )
Extract data: Location
Ecosystem Experiment type:(manipulative, mensurative)
Hypothesis tested Relative/Absolute Scale
Number of scales Scale dependence
CH1
A spatially explicit survey of pollination facilitation between Mojave Desert perennials and annuals.
Does the strength of pollination facilitation vary with guild (annual/perennial)?
How does shrub and cacti density and spatial distribution interact to influence pollinator behavior?
Kelso DunesUC, Riverside http://granite.ucnrs.net/?page_id=869CH2
All shrubs and cacti will be georeferenced using high-resolution GPS, tagged and identified to species.
Determine a natural replacement series of shrub:cacti
CH2
Phenology
Floral surveys every 8 -10 daysFl
oral
Abu
ndan
ce
Time
Shrubs
Annuals
Cacti
CH2
Seed Collection:
Shrubs:3 * 10cm diameter circle - mean
Cacti: 3 per cacti – Will need to weigh
Annuals:3 seed heads * 3 species per paired microsite: Microsite species should match understory
CH2
Pollen As visitation by shared pollinators increases,
heterospecific pollen transfer may also increase
A “cost” of pollinator sharing
Can create a pollen transfer network
Hub donors with positive effects on receivers – magnets
CH2
Predictions: Cacti will be non-randomly distributed
around shrubs Association of shrubs with cacti will be
species-specific
Hypothesis:Shrubs facilitate cacti through stress-amelioration
CH2
Annuals growing under shrubs or cacti will have greater seed set and pollen deposition than annuals growing in paired open site
Hypothesis:Shrubs facilitate cacti and annual plant reproduction by attracting shared pollinators.
CH2Seed
set,
polle
n de
posit
ion
Open Understory
Hypothesis: Pollination facilitation shows scale-dependence because pollinators make different foraging decisions at different scales Prediction: Seed set and pollen transfer to understory and open
annuals will decrease with increasing distance from cacti or shrubs.
CH2
Prediction: At small scales higher floral densities will lead to
increased pollinator visits, pollen deposition and seed set but at larger scales the interaction will change to neutral or negative
CH2
Distance
A contrast of local and regional density effects on pollinator facilitation.
• How does the density and distribution of shrub-annual complexes (magnets) affect visitation to low and high densities of annuals?
CH3
Low HighLow High
Annual Density
Shrub Density
4 replicates (1.5 hours) * 4 treatments * 8 days
CH3
Pollin
ator
Visi
tatio
n Ra
te
Low LowHigh HighAnnual Density
Low Shrub Density High Shrub Density
CH3