Archive for the 'Biology' category

The Answer to the Critter Quiz

Feb 28 2008 Published by under Biology, Science

On Tuesday, I posted a "can you identify this animal" quiz. I put a picture of an animal up, along with some information about it. The photograph was taken with the animal in captivity, at a location that was relatively near where the animal lived in the wild. The picture was not taken in Australia, and the DNA sequence that was superimposed over the image came from the animal in the picture.

Shawna was the first person to correctly identify both the species of the animal and the location where the picture was taken. The animal is a Brush-Tailed Rock Wallaby (Petrogale penicillata), and the picture was taken at the Honolulu Zoo. The species identification was confirmed by sparc, based on a BLAST search of the DNA sequence in the picture. (If you want a how-to on that, Sandy has an excellent one up on one of her sites.)

The wallaby in the picture was captured in June of 2005 on the grounds of Tripler Army Medical Center. It was transported first to the humane society then the zoo. It was held there for a few months, until the legendary Professor Steve Steve could find the time in his busy schedule to come out to Hawaii and show us how to properly handle the task of re-releasing it into the wild.

One response so far

A picture of a critter, and a puzzle.

Feb 26 2008 Published by under Biology, Science

Here's a picture of an animal that I took (and played around with) a few years ago. The DNA sequence that's superimposed over the picture came from that individual, so you can probably use it to figure out what species you're looking at (if you're so inclined). You can click on the image for a higher resolution version. The animal in question was (obviously) in captivity when the picture was taken, but it has since been re-released into the wild. It was held within 10 miles of the place it was captured, and the picture was not taken in Australia. Can anyone guess where the picture was taken? (Members of my family and Australian philosophers of biology are disqualified from this quiz.)

Wallyseq1

18 responses so far

How Many Species 3: Finally, some answers.

Feb 15 2008 Published by under Biology, Science

Last Thursday, I presented some data about three populations of an insect and asked you to try and figure out how many species scientists think these populations should be grouped into. On Monday, I added data from two more populations, and asked the same thing - try and figure out how many species are present. Now, I'm going to try and answer the question myself, and tell you what other scientists have said about these insects.

A quick review is probably in order before I get to the "answers":

The five populations are arranged in a line, with each separated from the next by a minimum of 5 km. The two populations at the NW end of the line share a reproductive characteristic with the population at the SE end, while the two populations between them do something different. The SE end population looks very slightly different from the other four populations. In lab experiments, none of the populations proved to be completely reproductively isolated from the others. However, the SE most population is largely reproductively isolated from all the others, and there's at least a slight reproductive barrier separating the two NW-most populations from the next two in the line.

Personally, I don't think you could make a good case for there being four species present here (at least from the information I presented), but I do think that reasonable arguments can be made for these populations being classed as 5 species, 3 species, 2 species, or 1 species. Below the fold, I'll give you the official answer. If you haven't read the first two posts in this series yet, you might want to look at them before you look at the "official" answer.

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6 responses so far

How Many Species 2: More Questions.

Feb 11 2008 Published by under Biology, Science

On Thursday, I presented a species problem taken from a post over at my old blog. I presented data from experimental matings that were carried out among three insect populations, added a little bit of information about the appearance, behavior, and location of the populations. I asked you to tell me how many species these three populations represented, and promised that I'd give you the "official" answer today. I've decided, though, that it wouldn't be totally fair to answer the question just yet. You see, I withheld relevant data when I presented the original version of the question.

When I gave you the information on Thursday, I just gave you data for some of the populations that were involved. There are two more populations that I didn't tell you about at the time. We'll call them Population D and Population E. Individuals from these populations were included in the original crossing experiments, and we also have data about their reproductive behavior and appearance. I'm going to throw these populations into the mix.

What I'd like to know now is this: how many species exist here in total, and which populations fall into which species? Here's the more complete set of data:

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7 responses so far

From the Archives: How Many Species?

Feb 07 2008 Published by under Biology, Science

This is a highly modified version of a post that appeared back at my old blog quite some time ago. Since it involves a quiz of sorts, I'm not going to post the link back to the original right now. The post with the "answers" will appear on Monday, also slightly modified from the original.

Taxonomy and systematics are the areas of biology that are involved in describing groups of organisms and determining how they relate to one another. One of the jobs associated with these disciplines involves trying to figure out whether or not two different populations of organisms should be considered to be part of the same species. Sometimes this is an easy job - it's pretty clear, for example, that polar bears and penguins are very different sorts of thing. Other times, it's a very hard job. The example I'm going to give you in this post is a difficult case, but a real one. I'll give you the details, and you can take your best stab at the question. On Monday, I'll tell you what the "official" view is.

There are three populations of a flying insect. These populations are physically separated from each other by areas of inhospitable terrain, and members of the populations are not known to come into contact with each other in the wild. Population A is found about 15 km to the northwest of Population B; Population B is found about 50 km to the northwest of Population C. In the past, the areas occupied by Populations A and B were closer together, and may actually have formed a single area. The area where Population C lives was never in contact with the other two populations.

There are no apparent differences between Population A and Population B in either physical appearance or in a specific reproductive behavior. Population C has legs that are a different color from the legs in the other two populations, but is otherwise identical in appearance. The reproductive behavior seen in Population C is very different from that seen in Populations A and B.

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5 responses so far

Assessing Diversity in the Past

Jan 24 2008 Published by under Biology, Geology, Science

Blogging on Peer-Reviewed Research

Over at Evolving Thoughts, John Wilkins has a post that criticizes a recently-published journal article. Normally, I agree with John - in fact, if it's true that the best measure of someone's intelligence is how often their views match yours, then John Wilkins is an absolute genius. But even Einstein had off-days, and (again, based on the agreement standard) I think this might have been one of John's.

The article in question, by paleontologists Sarda Sahney and Michael Benton, examines how long it took for ecosystems to recover after the end-Permian extinction. The dinosaurs weren't around then, so the end-Permian doesn't usually get the attention that the end-Cretaceous does, but it was by far a much more significant event. By some estimates, more than 95% of all animal species went extinct at that time. John's main complaint is with the way paleontologists compute estimates like that, and I'll explain why his objections are a bit on the idealistic side later on. First, let's take a look at what the authors did, what they found, and why their results are way cool.

When scientists study mass extinctions, they are usually interested in one of two things: what happened to cause the extinction, and what happened after the extinction. Both of those questions are important, not just because they help us understand what things were like millions of years ago, but also because they can help us better understand the potential consequences of some of our actions right now. In this study, Sahney and Benton are focusing on the second question. They want to know how long it took for new species to evolve and re-establish the level of diversity that was seen in terrestrial tetrapod ecosystems before the Permian extinction.

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3 responses so far

Somewhere, Yossarian is Laughing. Or: How Not to Fund Stem Cell Research at the NIH

There was only one catch and that was Catch-22, which specified that a concern for one's safety in the face of dangers that were real and immediate was the process of a rational mind. Orr was crazy and could be grounded. All he had to do was ask; and as soon as he did, he would no longer be crazy and would have to fly more missions. Orr would be crazy to fly more missions and sane if he didn't, but if he was sane he had to fly them. If he flew them he was crazy and didn't have to; but if he didn't want to he was sane and had to. Yossarian was moved very deeply by the absolute simplicity of this clause of Catch-22 and let out a respectful whistle.

"That's some catch, that Catch-22," he observed.

"It's the best there is," Doc Daneeka agreed.

The Bush Administration has once again managed to reach new levels of self-parody. This time, the subject is embryonic stem cell research, and they've taken a position on funding that quite literally incorporates a classic Catch-22 problem. Sadly, though, the Catch-22 lacks anything that bears the faintest resemblance to humor when it's used to block funding for potentially lifesaving research.

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12 responses so far

Coralline Algae and Global Warming

Blogging on Peer-Reviewed Research
Over the last couple of decades, a great deal of research has been done on the effect of global warming on coral reefs. The vast majority of that research has focused on the currently observed and potential future effects of climate change on reef-building corals. Coral, however, are not the only organisms that contribute to building a reef. A group of organisms known as the "coralline algae" also secrete calcium carbonate, and contribute to building up reefs. In a paper available online in advance of publication at Nature Geoscience, a group of researchers report on the results of an experiment conducted to observe what will happen to coralline algae by the year 2100 if atmospheric concentrations of carbon dioxide continue to rise at the present rate.

The experiment was carried out at the Hawaii Institute for Marine Biology's Coconut Island facility. The HIMB facility is extremely well suited to this kind of experiment, because it's location and facilities make it relatively easy to set up well-controlled experiments. Coconut Island is located in Kaneohe Bay, and is surrounded by a coral reef. There are both indoor and outdoor lab facilities available there, some of which are located within 10 meters of the reef, and the island has a seawater system that draws water directly from the reef. As a result, it's a lot easier to set up an experiment where you want to look at the effects of a change in one parameter on a reef environment at HIMB than it is in most other locations.

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Happy Birthday, Alfred Russel Wallace.

Jan 08 2008 Published by under Biology, Science

Today is the 185th anniversary of Alfred Russel Wallace. He's best known, of course, as the young(ish) scientist who, while recovering from malaria somewhere in Indonesia, independently came up with the same ideas about evolution that Darwin had been working on for three decades, wrote them up, mailed them to Darwin, and catalyzed the old boy into finally getting the damn book written. In fact, that part of his career is so well known that it's hard to find any mention of Wallace that doesn't also bring up Darwin. Despite his enormous talents as a naturalist, he's almost always cast as Darwin's sidekick. Today is his birthday, though, so it doesn't really seem nice to leave him in the Boy Wonder role. Instead, let's take a look at an outstanding paper that he published in 1855.

First, though, let's set the scene properly. By 1855, Darwin had spent nearly two decades actively investigating the evolution of species. For various reasons, he had not yet published his hypothesis, but he had confided it to a friend and colleague of his - botanist Joseph Hooker - in 1844. The question of how species were formed had been the topic of intense debate for years, and a number of scientists were approaching the topic from different angles. And Alfred Russel Wallace had been in the Malay Archipelago for about a year.

Although Wallace had spent some time around the fringes of the highly social and very upper class world of British naturalists by then, he was hardly an intimate member of their group. His modest background deprived him of the luxury of being able to pursue science as a hobby - unlike Lyell or Darwin, he had to work for a living. This turned out to be quite an advantage for him in some ways, though. He supported himself as a naturalist by collecting samples for wealthy people who kept natural history collections as a hobby. This meant that where some of his scientific peers might collect one or two samples of a species, Wallace collected - and examined - many more than that. It also meant that he had an enormous incentive to know what species lived where - it was his livelihood. Over the years that he'd spent time in the Amazon and the shorter time he'd spent in Indonesia, Wallace had looked at and thought about an enormous number of species of plants and animals, and had felt secure enough in his knowledge to not only report some of the facts that he had learned, but to also draw some more general conclusions from those facts.

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26 responses so far

Friday Arthropod - a fly from Hawaii

Oct 05 2007 Published by under Animals, Arthropods, Biology, Picture Posts, Science

Last week, I had a picture of a live spider for you to identify. Most of the guesses came quickly, and were absolutely correct - the spider in the picture was a Spiny-Backed Orbweaver. This week's arthropod might be a little more challenging.

The picture below features a pinned museum specimen, and was taken through a light microscope at about 40x magnification. The edge of a quarter appears in the photo for scale. The species in question is unique to the island of Hawaii, and is found on the wetter slopes of the younger volcanoes.

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4 responses so far

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