I’m in the final throes of collecting data on my experiment! I’m definitely ready to be finished, but there is much to do before the first frost hits.
Broken finger x-ray!
Unfortunately for me, my dog broke the 4th finger on my left hand two weeks ago (leash wrapped around finger+ cat = dog excitement + broken finger). I’m left handed, so it’s been challenging to collect data. But with some sweet “buddy tape” though, I’m making it work!
Shamed (but still cute) dog.
Data collection at River Terrace (rural field site).
I’m currently in the process of counting male female reproductive parts to get estimates of male and female fitness. By “parts” I mean the stalks with the male inflorescences (see the previous post on ragweed flowering) and the fruit. This is fairly time consuming, as you can imagine, especially since some of plants are well over 1 m tall!
The plants are starting to get pretty crispy and brown, which is to be expected as the summer season comes to an end. Plus the first frost in Minneapolis normally occurs in early October. It’s a race against time to finish data collection before they get zapped!
Once the reciprocal transplant experiment wraps up, I will embarking on a road trip in October/November to collect seeds from a whole bunch of populations in both urban and rural locations from Minneapolis to St.Louis to Dallas. These seeds will be used for an experiment next summer where I will be looking at continental-wide patterns of population divergence and adaptation in common ragweed as well as testing for evidence of convergent evolution in phenotype to urban environments.
Blue skies in rural MN
I’m going to write some regular posts about my collection trip (if anything just to post some photos of delicious t-ravs in St.Louis), but for now, here is a teaser photo I took out by one of of my Minnesota rural collection locales last week!
First of all – Happy Canada to all! If I ever get around to it, I’m going to make a page with amusing Canadian items, like the Long John Service Index of Canada.
The ragweed plants are happily growing and are getting huge! Last week I visited all my field sites to do some growth measurements on the plants at 6 weeks. There is a lot of variation in size of plants between the four field sites – the plants at the St.Paul site (urban garden) appear to be the largest, and those at the River Terrace site (rural garden) appear to be the smallest. I don’t know what is driving these size differences, however I have a feeling it might be due to soil differences between the sites. This gives me further motivation to do some sort of follow-up greenhouse experiment with the soil from these field sites to determine whether it is affecting plant growth and fitness.
Ragweed plants at the St.Paul field site (6 weeks, urban location)
Ragweed plants at the River Terrace field site (6 weeks, rural location)
The beginning of flower development on a ragweed plant at the Scooterville field site.
The plants have also started to initiate flower development! I was surprised to see this as A. artemisiifolia doesn’t normally start to flower until late July or early August. I will be tracking and recording the emergence of both the male and female flowers as the season progresses with plastic party swords – I have to keep data collection exciting, right?
It’s a little late, but finally a post about the experiment I’m doing this summer!
In Fall 2014, I collected seeds from multiple common ragweed (Ambrosia artemisiifolia) populations within urban Minneapolis and in the surrounding rural area. This summer, I am conducting an urban-rural reciprocal transplant experiment using those seeds to determine whether ragweed populations have adapted in response to the selection pressures present in urban and rural environments.
I have four field sites – two located in urban Minneapolis (called St.Paul and Scooterville), and two located in rural locations outside of the Twin Cities (called River Terrace and Rosemount). The Scooterville site is located on the University of Minnesota East Bank Campus and is part of the UMN Living Labs program.
Eric Holton (UMN undergraduate in EEB), tilling the Scooterville field site
In mid-May, I germinated the seeds in the greenhouse at the UMN and I prepared the sites for planting. This included lots of tilling, which is basically like using a giant lawnmower, but scarier. In early June, I transplanted the ragweed seedlings out into the four field sites (with the help of others, of course). Overall, the transplanting was a success and most of the plants survived! Hurray!
I’ll be collecting data on these plants over the course of the summer, and I’ll try to post an update now and then with some pictures too! Stay tuned for more on everyone’s favourite plant, ragweed.
Ragweed germinants successfully transplanted
The Rosemount field site after transplanting