Battle Royale: Part II

Erodium cicutarium, the non-native plant in the experiment. The other was Astragalus nutallanius, a native.

Just last week I blogged about the mystery plant in my calla lily’s pot, and how it’s an accidental ecology experiment. Today, Elieza Tang presented her summer research to the lab at our weekly meeting. She was paid by a Research Experience for Undergraduates grant for the summer, a category of money from the National Science Foundation, to do research on the effects of competition on the growth of two desert winter annual plants. She studied these in pots in special growth chambers  – kind of like my flower pot in my kitchen!

Why was she presenting her summer research in October? Did she not finish this two months ago? Actually, the two month lag time makes sense. This experiment, done in conjunction with the Portal project by Danielle Ignace and Peter Chesson, took some setting up and designing. Growth chambers break, experiments get delayed. Then it took months of watering, watching, and measuring as the seeds in the pots germinated and grew. And finally, once she had the data, she could set out to do one of the most difficult parts of an experiment: remember what the you-know-what her study was about in the first place! In all seriousness, analysis of the results can be one of the toughest part of science, because with a number of results that all vary a little bit, you have to prove there is a signal cutting through the noise that answers your question. The cigarette industry exploited this fact for years, using the noise in studies of cigarettes’ effects on health to argue there was no signal within it.

Like I mentioned, Elieza put seeds in pots, placed pots in growth chambers, and faithfully watered and measured them as they grew. Some of the plants had the whole pot to themselves, others shared it with seeds of their own species or the other species, and still others shared a pot with both types of plants. At the end of the experiment, she dug them all up and weighed them to see if plants with many competitors grew less. Many annual plants’ seed production is highly correlated with its size, so this is a good indicator of what the population might do in the future – grow or shrink. And there was one more wrinkle – she grew these plants at three different temperatures.

I won’t give away just yet what her results are, nor her conclusions and analysis. But I can tell you it’s exciting because it matches the researchers’ understanding of how these plants interact in nature, and fits nicely into the theoretical framework of the lab.

Feel free to leave a comment speculating what happened, or use this to change your bet on whether my calla lily will survive, or the mystery invader will.

 

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