In Praise of Collecting

One of the old standby activities of biology class is collecting, labeling, and classifying insects. I remember this was one of the true highlights of my life. When I was a young child I began collecting insects. The night before our collection was due several cute giggling girls in my ninth grade class showed up at my house asking if they could have some of my collection. The next week when we had our collections graded mine stood out among other less ambitious attempts which looked more like they had been collected with a shoe than a net. It was a rare moment where my nerdy habits were celebrated.

Rightly, insect collections have fallen out of favor in modern biology education. Bug collecting and classifying is hard to justify as a 21st century skill. 

Still, I think we shouldn’t forget about the value collections can have. Catching the bugs is a great way to compare and analyze biological forms.I think that there are two significant ways collections can be used in our evolution unit. 

First, collections allow students to consider the obscure insight of variation in a population.

consider how Alfred Russell Wallace arrived at his insight about natural selection. David Quammen explains in his book Song of the Dodo: Biogeography in the Age of Extinction  he explains,

“ Wallace had reason to notice such variation more clearly than most other naturalists. As a commercial collector, he collected redundantly- taking not just one specimen  each of this parrot ant that butterfly but sometimes a dozen or more individuals of a single species. Lovely dead creatures were his stock-in-trade, literally, and he grabbed what he could for the market. But after grabbing, he preserved, inspected, and packed his creatures with a keen eye, so he saw infraspecific variation laid out before him in a way that other field biologists ( including even the best of the wealthy ones, like Darwin) generally didn’t. it was a trail of clues that Wallace would follow to great profit.” (pg 65) 

This summer, I collected 133 Green June Bugs Cotinis nitida and then put them in a collection together.

Here you see the variation in Cotinis nitida as they go from bronze (left) to vivid green (right)

This gives students a vivid example of variation in a population. Most of the general public hasn’t seen the slight differences between individuals of the same species. Analyzing these collections can help them see the ingredient of variation that is necessary for of natural selection.

Shells can show this property as well, plus students can manipulate shells without breaking them. 

Shells can also help students to interact with the concept of biological variation. Students can manipulate them on their tables and sort them according to the variation that they see. (plus they’re fun to collect)

Secondly, collections allow students to very vividly see homologous traits and fossil evidence.

Last year I got out several of my collections and I had students move from station to station examining evidence for evolution. At each station I had either a fossil, a collection showing homologous traits/variation, a map for biogeography, a specimen with a vestigial trait/atavism, or a diagram showing comparative DNA.

Here students examine cowrie shells and find their “tooth like” structure. my goal is that they recognize that these similar species have a common structure due to a common ancestor. Looks like they’re having fun!

The students then had to apply what they knew about each evidence for evolution to a novel case. This proved to be a really fun experience for me because it forced me to apply what I was teaching in class to the world around me.

If that sounds like a whole lot to chew start with this; collect several pine cones from different species of firs, spruces, and pine. Challenge students with questions about why different species have similar structures.

At this station students were asked to consider why pine cones are so similar even though they are from different trees. In the physical examination of these structures homologous traits go from being an abstract idea to a physical reality.

Have your students examine these biological forms and identifying them helps you to move them from defining terms to analyzing and applying their knowledge.

Students comparing fossil ammonites to an extant Nautilus. I like that the evidence is in their hands not on a piece of paper. This allows them a more real chance to engage with the concept of evolution.

Kansas Fossil Search

Re-posted from the BioRx blog – http://wp.me/p4PfB2-1f

I finally had the chance to evaluate my sediment samples that we collected from the Flint Hills last week (I may or may not have been missing a PD meeting at the time… I was eager).  The beautiful sediment striation made me think that surely there would be some great micro-fossils in the soil.

Checking the samples.
Checking the samples.

Sadly, the dirt in the area is almost entirely eroded rock.  Under the microscope it looks almost like brown sugar.  It is possible to see where water bubbles had formed as the dirt was repacked after the weathering, which would allow some discussion with students, but nothing more substantial.  I was initially disappointed.  Then…

Alas, what yonder lies?
Alas, what yonder lies?

Well that is certainly something!  I cleaned the subject with a small painting brush from which I had cut/plucked most of the bristles for a very fine point.  I used the brush and a wire probe (an inoculation loop with the loop snipped off using metal nips) to center the find and turn it over.  Here is what I saw after the preparation:

IMG_20140807_122644

I wanted to jump to a trilobite identification, but something was bothering me.  This shape looked too familiar.  I spoke with a couple colleagues in my department, and no one could make a confident identification.  I worried that these remains may be a pill bug carapace that had been sun-bleached.  My department chair suggested that I evaluate the hardness of the sample, because fossilized remains should be harder (due to their replacement of many constituent substances with sediment) while more recent remains should be frail and brittle.  Using forceps I performed this evaluation and found that indeed the sample was highly fragile and was destroyed quickly during manipulation.  Ultimately I was left with one confirmed fossil in the entirety of my new collection.

IMG_20140807_141200
The lonely spoils: a gastropod impression.

Despite the low density of “keepers”, this exercise would have been great for students.  Acting on an informed prediction, testing a sample with multiple explanations, and ultimately confirming the less desirable explanation but still contributing to the understanding of the location are all a big part of the scientific process.  I will have to look elsewhere for local sources of fossils, but my understanding of the area is more complete now and I had a ton of fun doing some real paleontology.

I Teach Evolution, Do You? – Part II

Two weeks ago, I was struck by the information on biology teachers that I read in the article On Evolution, Biology Teachers Stray From Lesson Plan (duplicate post that you don’t have to login in to read) by Nicholas Bakalar.  At that time, I decided that I would share some of my thoughts and lessons that I used to teach evolution in my freshman Biology course. 

This particular lesson is the second of a series of activities that was conducted at the very end of the school year at the end of my unit on genetics after having covered standard Mendelian genetics and content associated with inheritance in humans.

The Biology of Race and Inequality

Lesson 1 – Comparing Chimpanzees using mtDNA Sequences (previous post)

Lesson 2 – Comparing Humans using mtDNA Sequences

Background – In the early summer of 2002, I attended a Dolan DNA Learning Center workshop at the Stowers Institute where a group of biology instructors were introduced to one wet lab and a number of bioinformatics activities associated with their new educational program called Genetic Origins.  Scott Bronson and Ewe Hilgert ran the workshop that specifically introduced us to the study of mitochondrial (mt) DNA and Alu genomic elements.

Objective– For students to apply what they learned in the previous activitiy on comparing chimpanzee mtDNA seqeunces to the analysis to human mtDNA sequences, and to realize that mtDNA comparisons do not support the concept of distinct human races.  

Because the previous activity demonstrated that mtDNA sequences were supportive of their being geographic subspecies of chimpanzees, many students will assume that the data for human mtDNA sequences will be just as supportive of geographic categorization of humans into races (they may even remember that Linneaus had segregated humans into distinct categories as well, although I would not reminded them of this directly). 

In the end, students should notice that the human mtDNA data is different than the chimpanzee mtDNA data, in that there is more variation within groups of humans than there is between those same groups.  In chimps there is significantly more variation between groups than within groups.  The main question that arises from this observation, is “Why is this so?”

Introducing the Activity – I do little introduction for this activity.  Since they would have just complete the comparison of chimpanzee mtDNA sequences, they know what to do and appreciate being allow to just get started.

Potential Supplemental Items

Although I haven’t used these resouces in conjunction with this specific activity, they may be nice additions that would provide students with background on the diaspora of modern human.

1. Spencer Well is Building a Family Tree for All Humanity (20:51)

I would now consider having students view this video for homework, although it is short enough that it could be viewed after they finished the activity above.  Here are some comments about Spencer Wells’ research on the TED website where this video is located.

By analyzing DNA from people in all regions of the world, Spencer Wells has concluded that all humans alive today are descended from a single man who lived in Africa around 60,000 to 90,000 years ago. Now, Wells is working on the follow-up question: How did this man, sometimes called “Y chromosomal Adam,” become the multicultural, globe-spanning body of life known as humanity?

Wells was recently named project director of the National Geographic Society’s multiyear Genographic Project, which uses DNA samples to trace human migration out of Africa. In his 2002 book The Journey of Man: A Genetic Odyssey, he shows how genetic data can trace human migrations over the past 50,000 years, as our ancestors wandered out of Africa to fill up the continents of the globe.

2. Humans May Have Left Africa Earlier Than Thought

Here are two NPR audio stories from this year that may be interesting as well, An Earlier Departure Out of Africa? (9:48) and Tools Suggest Humans Left Africa Earlier via Arabia (4:23).

3. Mr. Wallace’s Line by Jared Diamond (August 1997)

This is a great general introduction to Alfred Wallace and biogeography.  It mainly discusses non-human animal life in the Malay Archipelago, but there is a reference to  Tim Flannary and Jonathon Kingdon’ hypothesis that successful island hopping is responsible for making modern humans modern.  This thought takes a more interesting twist with the more recentdiscovery of Homo floreseinsis on one of these Indonesian Islands.

4. Luigi-Luca Cavalli-Sforza’s book, Genes, Peoples, and Languages (207 pages)

This is a great book that contains relevant background information on population genetics.

NPR Science: February 14

Week of February 14, 2011

Click on the logo above to go the the NPR Science site, or use the links below to navigate to one of the stories that I thought may interest you.

Last week, I showed my students my most recent NPR post and allowed them to pick the story title that most interested them to watch and talk about at the beginning of class.  They picked the video on the Meat-Eating Furniture and were quite intrigued.  Then, I showed them James Randi’s video on Homeopathy.  None of them had heard of homeopathic treatments but they appreciated being educated regarding the difference between these treatments and drugs that have been through FDA approval.

Happy listening!

Becoming Naked and Clothed

Exploring Human Evolution and Culture through the Study of Lice.

Yesterday evening I took the time to watch Nova Science NOW hosted by Neil DeGrasse Tyson.  Although I enjoyed the entire program, I was especially intrigued by the segment on the research of David Reed at the University of Florida’s Natural History Museum.

This segment discusses how molecular comparisons of our clothing, head, and pubic lice with the head and pubic lice found in chimpanzees and gorillas, respectively were used to infer the time when modern humans began wearing clothing, and when ancestral humans lost most of our hair.  With so much in the news lately about the diversity of human microbe flora, etc… this research could provide a clear example of the distinct niches that are found on the human body.

Watch the 11 minute segment at the Nova ScienceNOW, and then read the summary article In Lice, Clues to Human Origin and Attire from the New York Times, or download and read pdf’s of the scientific research below.

  1. Origin of Clothing Lice Indicates Early Clothing Use by Anatomically Modern Humans in Africa from the journal of Molecular Biology and Evolution.
  2. Pair of lice lost or parasites regained: the evolutionary history of anthropoid primate licefrom BioMed Central
  3. A list and some links to other publications can be found at Dr. Reed’s website.

I think this would make a great bioinformatics/molecular clock activity as well.