Hey guys, my name is Ally Ruttan and I’m a Masters student here at York University. I am going to talk to you today about myongoing work and some of my preliminary findings for my NSTP project which was a test of the magnet species hypothesis in Pink Mountains, BC, for the alpine plant Myosotis alpestris, or the alpine Forget-me-not.
Plants and pollinators rely on each other for many important life histories stages. While pollinators exploit plants for their floral resources including pollen and nectar, the majority of wild plants are reliant on this mutualistic relationship for pollination and consequently, sexual reproduction. Therefore, the co-evolution between flowering plants and their pollinators common and often necessary for ensuring acceptable levels of fitness and population sustainability. Pollinator mutualisms have been widely studied, especially in cases where the plant and pollinator have formed a rare obligate relationship, but indirect pathways also exist and are equally ]important. Plants have been thought to compete for pollinators in situations when many species are co-flowering in the same area, but pollinator facilitation has also become widely recognized as a mechanism for sharing access to generalist pollinators. In stressed environments where pollinators may be limited plant-pollinator facilitation networks are of particular importance
Many instances of diverse floral displays encouraging a net increase in both pollination frequency and pollinator diversity have been reported. This indirect pathway of neighbour-mediated pollinator facilitation is often termed the magnet hypothesis, and it has been shown to be important in many ecological situations. Basically, if you have a target plant species surrounded by neighbours, or “magnets”, this diversity can lead to an net increase in overall pollination compared to a target plant with no co-flowering neighbours of different species.
This diagram represents the direct and indirect interactions between plants and pollinators relating to the magnet hypothesis. There is a clear direct relationship between both the target plant and neighbouring plants with the pollinator community through pollination. The plants require pollination for sexual reproduction and the pollinators require nectar and pollen as sources of food. But, there is also an indirect relationship where the target plant, who competes directly for resources with neighbouring plants, obtains a net benefit through the attraction of additional pollinators.
Bigger plus indicates net increase, size = scale
Myosotis alpestris is a relatively small plant with little flowers that may struggle with sufficient pollination. So, the purpose here was to determine the importance of neighbouring plants for the pollination of Myosotis alpestris, specifically whether or not the plant is facilitated by or competes with neighbouring plants for pollinator visits.
The overarching hypothesis was that the presence of flowering will have an net positive effect on the pollination of Myosotis alpestris
Specifically, we predicted that: Visitation rate of pollinators will be higher when neighbours are present Pollinator richness will be higher when neighbours are present As these are only preliminary results, I am going to focus on the first prediction for this presentation.
This study was conducted in mid-July in an alpine meadow region on the peak of Pink Mountain, in Northern British Columbia. It’s one of the first mountains in the Rocky Mountain National Park range with an elevation of approximately 1700m
Pink mountain lends itself to this type of study as it is high in species richness, and has an interesting combination of alpine and tundra plant species, as well as diverse array of insect and vertebrates.
Pink mountain is home to a diverse array of insects, many of which are flies, particularly hoverflies, dance floes and flesh flies, but also many butterfly and moth species, bumble bees and even an Osmia species. Many of which are threatened or endangered.
Like I said, this study was conducted in a meadow region located on the peak of Pink mountain. Within this region, 20 experimental plots were randomly chosen and marked, with each randomly assigned to one of two treatments: neighbours intact, or neighbours removed. For the removal treatments, all flowers within a 50 cm radius around the target plant were removed and allowed to sit for a 24 hour period.
Here you can see a typical plot before and after the removal was done. The blue plant in the middle is my target plant, Myosotis alpestris. Before removal, the number of other flowers present of each neighbouring species was tallied, and the height of three target plant stalks were measured. Additioanlly, the distance to the nearest three bunchgrasses and cushion plants was measured, but data for this has not been analysed yet. Once this was all recorded, the neighbours were removed.
Here is a typical removal pot within the alpine meadow that this study was conducted in.
Once the characteristics of all the plots were measured and the removals were performed plots were allowed a 24 hour washout period. 20 iPods, fitted with blinds to precent shiny, reflective surfaces from showing were set up at each of these plots to record for 2 hours during peak visitation time (10-12am). Occasionally we had to alter these times slightly to avoid recording during periods of high wind, rain and hail. Pollinator visitation was recorded for an 8-day period, resulting in approximately 320 hours of video.
Here’s a typical video of pollinator interactions with my target plant
As well as some screenshots showing the diversity of floral visitors that are being ovserved while processing these videos
When processing the videos, we watch each of them in real time, and note the start and stop time of any instance where there is contact between an insect and a flower. Pollinator identity is noted as well as the flower species if it didn’t land on the target plant. Additionally, for each video, the number of target flowers in the field of view, the number of other flowers in the field of view and total video length was also noted. ----- Meeting Notes (2014-11-06 17:44) ----- Response variables
Here are some of my preliminary results. So far, we have processed approximately 10% of all the videos, making sure to analyze the same plots for each day. Here are the results for total visitation time. As you can see, visitation time was higher for no-removal treatments, where flowering neighbours were present though the results were not significant.
My GLM showed that day also an important effect, with cloudy/windy days resulting in less visits overall, so this trend may change once I have all my videos processed and can do a more extensive analysis.
----- Meeting Notes (2014-11-06 17:44) ----- contrast warm and cold days
Because total visitations were not significant overall, I decided to break these visits down by taxonomic group. Here are the results for lepidopteron pollinators which includes butterflies and moths. As you can see, treatments with neighbours intact and no removals had significantly higher insect visitation time compared to removal treatments.
----- Meeting Notes (2014-11-06 17:44) ----- dump error bar caps, simplify axis with less scale
Similarly, hoverflies were also attracted to plots with neighbours significantly more than those without neighbours. Very few visitors were reported at all for hoverflies in removal treatments.
Interestingly, Empididae, or dance flies which appeared to be the most common pollinators of my target plant visited removal plots at a much higher rate than non-removal plots with neighbours intact. It’s possible that these flies are seeking out a particular search image to find Myosotis alpestris but at this stage we’re not really sure why. ----- Meeting Notes (2014-11-06 17:44) ----- Shows that even with plant facilitation, if this result holds, doesnt mean every single insect obeys the magent law. Specialists may fuction diferently than generalists.
The main conclusion is: NEIGHBOURS MATTER! And they can have important effects, both positive and negative, on the pollination of a target plant species.
Neighbour presence and identity can influence polliantion both positively and negatively depending on both the plant species and pollinator species. At this stage, we’re not sure yet if there is a net benefit for pollination overall when neighbours are present that supports the magnet hypothesis, but the data suggest that this may be the case.
In areas such as the alpine where there are harsh abiotic conditions, pollinators are often scarce. Facilitation between plants for shared access to pollinators is therefore a very important pathway that may allow many plant species to persist that would not be there otherwise.
I would like to thank my supervisor, Dr. Chris Lortie, as well as the ecoblender lab, especially Amanda, Alex, and Ty who were really helpful in the field. I’d also like to thank Ron Long and Daniel Mosquin and Anya Reid for their help with field logistics, plant identification and getting us all acquainted in the field. And finally, I just want to thank the Northern Studies training Program and the Canadian polar commission as well as NSERC for funding this project.
A test of the magnet species hypothesis for the alpine plant, Myosotis alpestris
A test of the magnet species
hypothesis for the alpine plant,
Facilitation = Positive
Many plants rely on insects for pollination and co-evolution is common
Facilitation between plants and pollinators = shared access to resources
Neighbour presence and identity influences
visitation rate and distribution associated
with flowering plants
Preliminary evidence indicates not all
insects are necessarily subject to magnet
Facilitation is important in alpine where
there harsh conditions and scarce
How will these plants respond in the face of climate
Ecoblender lab, York University
Ron Long, Pink Mountain Biodiversity Initiative
Daniel Mosquin, Ed./Tech. Manager, UBC Botanical Garden
Anya Reid MSc, Ministry of Forests, Lands, and Natural Resource Operations