Sunday, April 28, 2013

Orcas and Sea Otters

Here's the paper we were discussing in class week about orca predation on sea otters. It attributes this unique predator-prey relationship to anthropogenic factors and relates to the collapse of Steller's sea lion and harbor seal populations along the west coast of North America. A corresponding decrease in populations of sea birds has been observed, pointing to a reduction in important prey (and commercial) fish populations. It's a fascinating example of the effect that "uncommon and transient species can have in controlling community structure," in a top level predator.

Wednesday, April 24, 2013

Real-life faries?

I found this article on Yahoo today that was discussing a new type of insect which they appropriately named Tinkerbell nana after its feather-like, fringed wings. This fairyfly is tiny, only about .0005 inches in length when its full grown but it is very helpful in farms and other agricultural areas because it feeds off the eggs and larvae of insects. The link below has the rest of the article and couple pictures of the fly which are pretty interesting.

Tuesday, April 23, 2013

Ant careers

From the journal Nature this week:

Tracking whole colonies shows ants make career moves

Comprehensive tagging reveals workers switch tasks as they age. Computer tracking of tagged ants demonstrated that workers divided into three specialized groups — but often switched groups as they aged.

Monday, April 22, 2013

TB cases from early Neolithic period

I am researching the evolution of tuberculosis for my evolutionary medicine class, and I found this really interesting article about how TB can be traced back thousands of years. It's quite amazing to think that this disease has been with us for so long, and yet is still prevalent today as HIV spreads and multi drug-resistance becomes more and more of a problem. Worth a read if you have a bit of time.

Rib Lesions in Skeletons From Early Neolithic Sites in Central Germany: On the Trail of Tuberculosis at the Onset of Agriculture

Sunday, April 21, 2013

Using Differential Equations for Population Ecology

In class, we covered exponential and logistic growth; however, systems of differential equations is an approach to model population growth with two species, often referred to as Lotka Volterra Predator-Prey models.

You start with two equations:

  • the rate of change in population of the predator with respect to time as a function of the populations 
  • the rate of change in population of the prey with respect to time as a function of the populations

You then form a matrix representation of the functions and find the eigenvalues and eigenvectors, which are used to plot a phase diagram (a graphical representation of the solution to the differential equations). The magnitude and sign of the eigenvalues determine the stability of the fluctuations between the populations of the two species and the rate of growth of each population. Of the several different possibilities for the phase diagrams, there are two relevant situations: concentric circles, or saddle point. 
The concentric circles represent populations in a stable relationship, as shown below.
A saddle point is unstable and suggests the extinction of one of the populations, as shown below.

This is a topic that was covered in Math 4B, but you can also read about it here

Bio Engineered Organs

Organ transplants have always been a tricky business, first you have to find a viable match for the person who needs it and then there is always the chance of rejection.  Scientists have dreamed of building organs in a lab but generating the structure of a working organ has always been a tricky prospect.  However due to a recent study at Harvard this dream is becoming more real.  Scientists have successfully stripped a cadaver rat kidney of all native cells leaving only and cellular matrix of the kidney and have successfully implanted the


hosts cells and grew an functional kidney which was later successfully implanted in the host rat.

Monday, April 15, 2013

Sea Lion Keeps the Beat

Dancing may come naturally to (some) humans, but it doesn't quite have a parallel in the animal kingdom. A sea lion named Ronan is the first non-human mammal to show she can move to the rhythm of a song.

Wednesday, April 10, 2013

Chemical Treatment Makes See-Through Brains

In the article, "See-through brains clarify connections", a breakthrough in neural mapping is described. Scientists have found a way to make organs clear, which especially helps with the brain, which we have had to cut into slices to map out. The process works by first creating a system to hold the cells in place, and then dissolving the lipids. They are then able to run a dye through whichever parts of the brain they want, and they are provided with a 3D model of all the the brain's circuitry. This video from the article takes you through it pretty well:

Tuesday, April 9, 2013

Moral behavior in animals

Empathy, cooperation, fairness and reciprocity -- caring about the well-being of others seems like a very human trait. But Frans de Waal shares some surprising videos of behavioral tests, on primates and other mammals, that show how many of these moral traits all of us share. 

The two video clips I showed in class are from this TED talk. The whole talk (only 17 minutes) is well worth watching.

If you are one of the few people to have NOT watched Battle at Kruger on YouTube (71 million views!)  then you should watch it now. 

Sunday, April 7, 2013


 Bruce passed this on. Although it is a specific problem for biomedical science the issues described are relevant to all science.

Thursday, April 4, 2013

Two reminders

This is a FINAL reminder for those interested in a Summer Undergraduate Research Fellowship (SURF) in summer 2013, the application and letters of recommendation are due **Monday, April 8th**, only a few days away! Check your e-mail from Jen for the required forms.

The Undergraduate Research Colloquium (a poster exhibition only), on Tuesday May 21, 2013, recognizes the scholarly achievements of students and acknowledges the faculty contributions to the development of undergraduate research and creative activities.
The submission of the online colloquium entry form is required. The online entry form will open in February 2013.  The 2013 Colloquium entry deadline is Wednesday, April 10, 2013.  We will attempt to accept all applicants; however, if we can't accommodate everyone, a faculty panel will select participants. 

Tuesday, April 2, 2013

Maria Sibylla van Merian

Bruce pointed out this very cool Google doodle for today in honor of Maria Sibylla van Merian.

I'll also take this opportunity to remind you of Ron Vale's talk tomorrow:

- 3:00-4:00 Talk in Marine Science Building Auditorium “Building the Mitotic Spindle”

4-5:00 Reception at MSI

~ 5:15 - 6:15 Pizza with CCS Students in the Gallery.

Please let Jen ( if you plan to attend so we can order enough food!