November 2012 Archives

Hi everyone,

Maria here at CBG. On Tuesday, I came back from Thanksgiving break to find that one of the Dichanthelium plants in the growth chamber was flowering like crazy!

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So many flowers! It was also interesting that the plant that flowered looked more stressed (yellow leaves) than some of the other plants.

Today, I collected some pollen (shook the spikelets) on glass slides, stained them with 0.1% toluidine blue, and looked at them under the microscope. It was amazing to see the stained pollen, and how different the viable and inviable pollen looked! I wish I had pictures. I will be learning how to take digital microscopic images (hopefully tomorrow?). So hopefully I'll be able to stain pollen from all flowers tomorrow, take pictures of the stains, and count pollen to get a sense of levels of viability in Dichanthelium pollen.

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As you can see in this lovely motivational diagram, we finally finished counting last year's achenes from the 1999 experimental plot.


The next step for this batch will be to collect a random sample of achenes from each flower head to estimate pollination rates. We can tell whether an achene is "full" (contains an embryo) or "empty" (does not contain an embryo) based on its weight. We can estimate pollination rates based on the ratio of full and empty achenes. However, there are some achenes whose weight does not give us any information about pollination. Some are so small they never produce an embryo, some are damaged by insects, some are damaged during removal from the flower head, etc. If we weighed these, they would show up as "empty", even though they may have been pollinated. Therefore. when we select a random achenes for weighing, we have to differentiate between those that are informative about the pollination environment (full or empty) and those that are not informative (small, sterile, damaged, etc.).

For this batch, we are starting a new randomization protocol that assigns achenes to categories of "informative" (possibly full or definitely empty) and "uninformative" (sterile, undersized, damaged). Both are part of the random sample, but only the informative achenes are weighed. It's a subtle distinction from what we were doing before, but it will be important for our results.

Now that we have reached our goal in counting, we have started processing the heads we harvested in 2012. Today volunteers Katharine and Sam are trying out a new protocol for removing the achenes from Echinacea heads. Previously, we through away any dust left over from removing achenes. This time, we are saving the dust in separate envelopes. That way, we will be able to figure out whether the dust we throw away contains fragments of achenes. Also, we will be able to compare scans with and without the extra dust to see whether removing dust makes a difference in the accuracy of our count data.


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We had a lot of people in the lab last week. On Wednesday, we had volunteers Kathryn Eber and Sam Goldman along with a group of interns from Lakeforest College:




The Lakeforest students will return for two more afternoons--or longer if they so choose.

In other news, we are nearly finished counting the seeds from the 4000s batch in the 2011 harvest. For this batch, we are trying out a new protocol for selecting a random sample of seeds to weigh. Volunteers Suzie and Susanne were the first to implement the protocol and have given us some good feedback.

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This week has brought us further along on our goal of counting and randomizing all of the achenes from 2011. Here is volunteer Kathryn Eber, looking pleased to have her picture taken. Thanks to her and the other volunteers, we are nearly finished counting the 4000 batch of the 2011 harvest.


On Wednesday October 31st, we welcomed several students from Lakeforest College for the first session of a four week internship. Meet Randen, who is working with me to learn how to identify ants:


When he came in, he had no experience identifying insects or using taxonomic keys. By the time he left, he was able to identify ants to genus and--for some genera--to species. His project is to compare ant species collected from burned and unburned units of the Staffenson prairie preserve. Ants are a crucial component to terrestrial ecosystems: they move dirt, they prey on many critters, and they protect other critters like aphids. If fire influences the community of ant species in a prairie remnant, there may be cascading effects throughout the ecosystem. Naturally, I'm excited to see what Randen finds out during his project.

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