Sunday, March 25, 2007

Homework for 3/28

(readings forthcoming?)

Rick has asked that:
"each of you look into any evidence that your species has ever or could potentially hybridize with related taxa...Look around for wide crosses (between subspecies or varieties even)...In introduced regions we saw that often introductions are from different regions of the native habitat. This, as you know, introduces greater variability and generates different combinations than are present in native regions."

Readings for 3/26

Rick will be lecturing this week, here is a recap of the readings for Monday (emailed by Rick to everyone last week):

  • "Hybridization as a stimulus for the evolution of invasiveness in plants?" by Ellstrand and Schierenbeck (2000) Proceedings of the National Academy of Sciences. 97(13): 7043-7050 (link)
  • "Hybridization, polyploidy and speciation in Spartina (Poaceae)." by Ainouche et al. (2003) New Phytologist. 161: 165-172. (link)

Monday, March 12, 2007

Readings for 3/14

For this class we will be taking a look at present invasive species vectors, with a focus on the type of organism you chose for your semester projects.

Each of you has been assigned two readings, based on the type of organism you are studying. That means some of the articles will only be read by one person, others will be read by many. You should be prepared to discuss the key points of your paper, and think about these questions: What are the specific pathways discussed? Are they obvious or obscure? Are they vectors for a few species or many?

Thursday, March 8, 2007

Readings and Homework for 3/12

Reading for Monday, 3/12:

  • "Changes in the Sea." Chapter 5 in Elton, C. S. (1958). The Ecology of Invasions by Animals and Plants. London, Chapman and Hall, Ltd.
  • Fosberg, F. R. (1958). “Man as a dispersal agent.” The Southwestern Naturalist 3: 1-6.

Also, be prepared to discuss the vectors of introduction and spread for your adopted species.

Tuesday, March 6, 2007

More about Butomus umbellatus

Rick spoke briefly about flowering rush (Butomus umbellatus) in Monday's lecture - it's the species that was being compared with purple loosestrife. Both are typically emergent wetland plants - growing surrounded by water but rooted in the substrate. Flowering rush is a monocot in its own family, the Butomaceae. Like purple loosestrife, it is on the Massachusetts list of banned invasive plants.

Perhaps not coincidentally, it has also been the subject of an evolutionary study similar to the reed canary grass paper we will be discussing in class Wednesday. This is absolutely not required reading, but for those of you who are interested, here is the citation:

Brown and Eckert. 2005. "Evolutionary increase in sexual and clonal reproductive capacity during biological invasion in an aquatic plant Butomus umbellatus (Butomaceae)." American Journal of Botany. 92: 495-502.

Sunday, March 4, 2007

Class for 3/7

On Wednesday we begin a new section in the syllabus, "Vectors of Invasion - The Early Years"


  • "The Crown's Relationship with Acclimatization Societies" Chapter 8 in Effective Exclusion?, a report prepared by the Waitangi Tribunal. Read pp. 495-512 (8.1 through 8.3.1) and 529-533 (8.8) (This is a large document, you do not need to print the entire thing)
  • "Weeds" - Chapter 7 in Crosby, A. W. (1986). Ecological Imperialism: The Biological Expansion of Europe, 900-1900. New York, Cambridge University Press.

Class for 3/5

Rick will be covering the second part of his section on invasive species and population genetics, papers were already assigned back when the class was originally scheduled. A note from him...

We are looking at population genetic factors that might be important in altering the evolutionary path (or trajectory) on an introduced species. We covered bottlenecks and inbreeding, factors that impact small populations. I gave some examples of these and discussed (briefly) how these are measured (with diversity statistics). We were then beginning to discuss some case studies. I will present some info on two Water Hyacinth and Cheatgrass (which Jenn mentioned last class as well) and then we will discuss the ants and other examples.

Later in the semester, I will be continuing this theme of "changing evolutionary trajectories" in a discussion of hybridization and rapid changes/responses to selection pressures.

In addition, there is a new article out about reed canary grass (Phalaris arundinacea) that Rick sent out a copy of this weekend:

Lavergne, S├ębastien and Molofsky, Jane. 2007. "Increased genetic variation and evolutionary potential drive the success of an invasive grass." PNAS. 104(10): 3883-3888.

Please be sure to at least look at the abstract and figures of that paper if you do not have time to read the whole article.