Thursday, December 25, 2008

Christmas Tree Biology

I'm not a particularly big fan of Christmas insanity, and I have never intentionally purchased a Christmas tree greater than 10 inches tall, but this is the best "Christmas" themed topic I could imagine while trying to deal with sick kid and wife.

To start with...what is a Christmas tree (not going to assume anything here)?  The typical
 Christmas tree is an evergreen tree (Pinophyta or Conifera), typically a fir, brought inside and
 decorated with all kinds of shiny bright objects.  According to the, actually the U. of Illinois Extension Office, there are 36 million Christmas trees sold every year, and 73 million planted yearly.  That's a lot of Christmas trees, and they are planted at an initial density of over 2,000 per acre.  For comparison, in the state of Kansas, tree mitigation plantings are typically
 done at 640 trees per acre.  So we are talking some really high initial densities.  Of course anything sold by the millions will have government oversight.  Feel free to peruse the absolutely tedious USDA Christmas Tree Grades. (pdf warning...not that anyone's going to read that!)  Wow.  

About 95% of the real trees purchased come from farms.  According to the National Christmas Tree Growers Association, a few are allowed to be harvested from National Forests.  And let's take a moment here to appreciate that yes, there is a National Christmas Tree Growers Association and yes their 'Mythbusting' article is just as ridiculously snarky as anything I've ever read by a glorified PR firm.   The article is actually about the "Great De-Myth-ification Campaign".  I'll offer a quick summary:  Fake trees suck.  Although I'd prefer this message
 wasn't coated in a thin vaneer of hazy logic and silly attacks at the fake tree industry, I tend to think that environmentally, a real tree is probably a lot better.  

Why?  Well...As stated above, the real trees are grown on farms, and although it sounds like there are a lot of pesticides and other petroleum products used in their management, at least we're not talking about a completely manufactured product.  Of course, this is all a straw
 man...the real question is why have one in the first place?  Oh, you know, lots of culture and stuff.  Didn't I say I was going to talk biology?

I usually refer to conifer trees as evergreen trees.  Can anyone in the class tell me why that's not really a good term?  Yeah, that's right, because not all 'evergreen' trees are conifers.  Consider plants in the tropics:  None of them drop their leaves seasonally.   So let's stick with conifers.  

Conifers are typically distinguished by their leaves and reproductive organs.  The leaves are usually thin and waxy, allthough some are more like scales (see examples).  These leaves minimize water loss and maximize light absorption (especially in cold and dry climates).  As expected, almost all of them keep their leaves year-round even in temperate or northern climates, but a few do not.  Conifers tend to do better in cold or arid climates (i.e., northern or high altitudes) and can get really really big (Giant Sequoia).  I don't know anything about the evolutionary history of conifers, and nobody on the web is really giving me a lot of info on this.
  The best I can say is that conifer-like plants emerged around 300 million years ago.  There are currently ~700 species of conifers, which is actually a really small number for such an
 ecologically important group of plants.  By comparison, there are estimated to be 250-400,000 species of angiosperms.  Wow.

A typical Christmas tree takes about 7-10 years to grow.  Out of the 2,000 per acre planted, only between 750 and 1000 per acre will survive, which is still a heck of a lot.  Keep in mind that just because a plant is chopped off at the base and stuck in your living room it is still alive.  That tray at the bottom of the tree isn't just for the dog and cat to drink out of, its to keep your tree living.  Firs tend to not lose their needles easily even after dying and drying, but other species will, and keeping the trees well-watered will reduce that.  You'll also get more of the 'tree smell' that so many people (myself included) find awesome.  

I know that was a sorta non-sciency post, but I've been busy and its Christmas.  Merry Christmas!

Thursday, December 18, 2008

Species Profiles: The Bald Eagle

The process of listing and de-listing a species in the state of Kansas is both confusing and simple.  If a species is listed by the feds, it is automatically added to the Kansas list (if it is an animal).  On the other hand, if a species is de-listed by the feds, the species must be petitioned to be delisted in Kansas.  For most people I talk to, their reaction to this is that's stupid.  As I've discussed elsewhere, often there are very good reasons to continue to protect a species in one area that may be far from threatened elsewhere.   

However, the most recent round of petitions for listing or delisting species in the state of Kansas is now up for review, and the Bald Eagle (Haliaeetus leucocephalus) has been the subject of delisting petition (along with the Peregrine Falcon and the Broadhead Skink).  In my professional duties for KDWP I am not a part of the
 committee that determines listing or delisting of species, but I have heard that the Bald Eagle is likely to be delisted.  So I figure I better get a species profile of this popular bird up before it is out of my realm of interest.

How much introduction does a bird like this need?  Americans are well aware that the bird serves as a (perhaps the) national icon.  Less may be aware of Benjamin Franklin's scathing criticism of t
he bird (sources here and here):
I wish that the bald eagle had not been chosen as the representative of our country, he is a bird of bad moral character, he does not get his living honestly, you may have seen him perched on some
 dead tree, where, too lazy to fish for himself, he watches the labor of the fishing-hawk [osprey], and when that diligent bird has at length taken a fish, and is bearing it to its nest for the support of his mate and young ones, the bald eagle pursues him and takes it from him.... Besides he is a rank coward; the little kingbird, not bigger than a sparrow attacks him boldly and drives him out of the district. He is therefore by no means a proper emblem for the brave and honest. . . of America.. . . For a truth, the turkey is in comparison a much more respectable bird, and withal a true original
 native of America . . . a bird of courage, and would not hesitate to attack a grenadier of the British guards, who should presume to invade his farmyard with a red coat on.
That bit about the turkey, it doesn't necessarily come from Franklin's support of the turkey as a national bird, but 
rather from the poorly drawn seal from the early continental congress (shown below).  The Eagle was also an important bird for Native American Mythology, although the Golden Eagle (Aquila chrysaetos) was probably much more abundant throughout the continent.  

All eagles fall into the Accipitridae family, although where they fall is a matter of some dispute.  As befits one of the most well-studied species in North America, relatively more is known about the bald eagle than some other eagles.  Bald eagles fall into the Sea Eagle category, and are almost morphologically indistinguishable from their nearest living relative the White-tailed Eagle (or just Sea Eagle).  That species pair diverged from other eagles ~10-20 million years ago. 

This bald eagle killed a whale!  Or found one dead on the beach...Same difference.

I tend to get very bored when talking about birds because I have poor eyesight and don't really see them very well out in the field.  So let's talk about why I and many other people have no problem seeing lots of small birds (e.g., sparrows, swallows, cowbirds, etc.) and hardly ever get to see a bald eagle or heron from close up.  Surprisingly enough, it probably has a lot to do with energy kinetics.  

See, smaller birds, mammals and lizards tend to contract their skeletal muscles faster than larger birds, mammals and lizards.  In the case of birds, this means faster (and more powerful) wingbeats per unit muscle in a sparrow than a bald eagle, so a bald eagle has to pack on a lot more muscle to get the same amount of acceleration.  All that extra muscle means that big flying birds exist right at the limit of being able to fly at all.  So those big birds end up using a lot of 'runway' to get off the ground.  I'm sure everyone has seen a duck or goose running across a pond or lake before taking off.  Those birds are not only big, but they are heavy, and built for long migratory flights across continents.  

As a result of all that, the proximity that triggers a flight response from a bird varies tremendously.  Small, mobile birds can get off the ground and out of danger very quickly, whereas a bald eagle takes a few moments, and a goose takes even longer.  So a sparrow will let you get a lot closer than a bald eagle.  This is also why you occasionally see a few small birds harrassing a large hawk.  The hawk is simply incapable of manuvering its bulk around in the air fast enough to deal with the smaller birds.  

Back to Bald Eagles?  Ok, sure.  The Bald Eagles are top predators, and primarily fish eaters (as the whole Sea Eagles thing implies).  They tend to stick to major river corridors in continental interiors and congregate along coastlines.  Alaska has the largest population of existing Bald Eagles, despite a concerted effort by salmon harvestors to kill them off in the early 1900s.  In general, the eagle was the subject of human harassment and competition, and dramatically declined from pre-Columbian levels as the United States became more populus through the 1800s and into the early 1900s.  Protection for the Bald Eagle was first enacted long before Federal Threatened and Endangered Species laws, by the Migratory Bird Treaty and the Bald Eagle Act.  

Those laws might have worked to restore Bald Eagles if not for the Greatest Generation's plan to kill everything on the planet.  What am I talking about?  DDT.  DDT is arguably a huge boom to mankind, since it basically eliminated malaria from large portions of the globe, but it also caused dramatic and unanticipated impacts on human and environmental health.  The overuse of DDT and similar pesticides essentially created the modern environmental movement (see Carson, Rachel), and lead to the passing of the federal Endangered Species Act.  

Unfortunately, since its passage, the ESA has been more-or-less continually gutted in favor of economic conerns, and only a few species have ever been successfully removed from the Endangered Species list.  (I could go on and on about why the ESA isn't a great idea, but the reality is that it isn't a terrible idea either).  On June 28th, 2007 the Department of the Interior announced the Bald Eagle was going to be delisted, which came as little surprise.  The Eagle's numbers have been rising dramatically in recent years.  I've personally seen over 20 in the last year despite living in Kansas, where they are very scarce.  

I even saw one today.

Thursday, December 11, 2008

Reptiles: Because I'm out of good ideas

I've got some projects in the pipeline, but none of that is ready yet. So let's talk about does that sound?

Reptiles are air-breathing, four-legged, cold-blooded amniotes that live everywhere but the polar regions. Everyone knows what a reptile is, but oddly enough, the taxonomy is a little more confusing that we might otherwise think. To understand why, I'm going to introduce two terms: Monophyletic and paraphyletic. Basically a group is considered monophyletic if it includes all the animals desended from a common ancestor. If you take a monophyletic group, and remove one of the decendents of that common ancestor, then you get a paraphyletic group.

Full of confusion? Ok, let's put it another way. Below are all the vertebrates. If we highlight a group that includes reptiles and birds, we've got a monophyletic group (sometimes called a clade).

This figure shows our best understanding of evolutionary connections. The earliest common ancestor was some kind of vertebrate, which split into tetrapods and pisces (fish). You can see tetrapods split into amphibians and amniotes.

On the other hand, the group 'reptiles' as we commonly understand it, isn't a monophyletic group. Take a look:

The term reptiles doesn't include all descendents from a common ancestor because the are believed to be part of that lineage as well. The reason this is a little weird has to do with the way humans percieve these groups of animals. Birds and mammals are 'good' animals. Reptiles and amphibians are "slimy", creepy or scary. Yet these are very different types of animals. As you can see in the figures above, they aren't even that closely related.

This perception problem is pervasive in the sciences as well. Take herpetologists. Herpetologists study reptiles and amphibians. The only real commonalities are that they are cold-blooded and generally smallish. Is this really a meaningful basis on which to lump these otherwise very different groups together? (

Ok, but let's get back to reptiles. I've repeatedly used the term amniote without really explaining it. Maybe I should fix that? Amniotes are animals who's embryo is surrounded by protective membranes: They lay eggs that could survive on dry land! This improvement on eggs was the big development that separated the earliest reptiles and proto-mammals from the amphibians. At the time, amphibians were the masters of the terretrial terrain. However, amniotes were able to exploit a lot more land, and eventually began to displace amphibians as large, dominant herbivores and predators.

Reptiles, or at least, creatures that we would look at and think "reptile" predate mammals, and therefore you can safely consider mammals and birds specialized reptiles, if you feel like it. Those of you who think I'm crazy: Its right there in the family tree!

What did an early proto-reptile look like? Well, according to Wikipedia, Hylonomus is a good guess for one of the first reptiles:

Oh my gosh! It looks like a lizard!

Yeah, that was predictable huh? There are only 4 classes of reptiles left today (if you don't count mammals or birds). The crocodiles and the turtles are two of those classes. The third one is everything else you think of as a reptile: Snakes, lizards, mosasaurs (these are squamates). Unless you're amazing or a herpetologist, you probably have never even heard of the 4th group of reptiles. Why? Because (this is going to be a huge shock) even if you saw it, you'd just think it was a lizard.

I'm talking of course about the order Sphenodontia, a once hugely diverse order that now contains just a single species: Tuatara. And if you know anything at all about how the world works, you know this single remaining species of a once-great order is on the verge of extinction thanks to something mankind did. Fantastic. In this case, we brought rats to New Zealand.

Tuatara is a pretty ridiculously interesting animal. Like the last surviving member of any ancient lineage, people tend to refer to this species as a 'living fossil'. However, this has always been a hopelessly stupid thing to say. The implication is that the animal hasn't changed in the thousands or millions or tens of millions of years since our first fossil record. The likelihood of this being the case is incredibly small. Animals evolve to survive changing conditions, and there is basically no-where in the world that hasn't had changing conditions over the last 220 million years. Hence, this species had to have evolved. In fact, these guys (whose work I can't get anywhere) apparently found that tuatara is changing more rapidly than any other species tested.

Ok, aside from that tuatara has a third eye, incredibly primitive ears, and a fish-like spine (all unique or rare among reptiles). And now let's go back to reptiles.

There's a lot about reptiles is amazing, but I'm just going to talk about one more thing and leave it at that. Basically: How do they breath?

This seems like an obvious question. After all, we all instinctively know how mammals breath, and if you dig around the medical literature, you'll find talk about a diaphram and muscles causing your lungs to expand and contract.

Of course, this is how reptiles do it too, but in the case of the squamates, those muscles are also locomotion muscles. So when a lizard starts running, it isn't breathing. I haven't found anyone who says this, but I imagine this is why you see lizards making short bursts from hiding place to hiding place. The crocodilians breath differently. Like mammals, crocs have a diaphram (although it works a little differently). Turtles are where it gets really interesting. I don't know how many of you have seen a turtle, but they have a hard shell. Exactly how do you get your lungs to inflate and deflate if they are attached to a hard shell?

Turns out, different turtles do it differently. For the most part, there are two sets of muscles: One that pushes everything inside the shell out, and another set that pulls everything outside the shell in. Expand-contract. You get the idea. These muscles might interfere with locomotion, or they might not, depending on the species. You may also think: Aren't there a lot of aquatic turtles? Why yes, yes there are. And since you asked, some of them appear to breath from the butt.

Don't worry though. They aren't drinking from that oriface.

Well, that turned into a sufficiently bizarre post. Hope everyone enjoyed!

Anonymous Rattlerjen said...

Fantastic post on reptiles, and fund to read.
Turtles and tortoises do drink from their cloaca (yes, the bottom or aka anus). Many turtle species cannot "drink" unless they are sitting in water!
As for the breathing part, many aquatic turtles are able to hold their breath for a long time because they are able to absorb oxygen through their skin or cloaca. How weird is that!

As Rattlerjen points out, yes, its really the cloaca that turtles are able to respire from (butt is a non-technical term in this case :), although this is limited to side-neck turtles. However, I can't find any actual evidence to back up Rattlerjen's other claims. The paper I linked to previously (the link doesn't seem to be working, so the citation is below) actually demonstrates that cloacal drinking does not occur in a species that is able to breath that way. Anyone have any citations to share on other species?

Charles C. Peterson and David Greenshields. 2001. Negative test for cloacal drinking in a semi-aquatic turtle (Trachemys scripta), with comments on the functions of cloacal bursae. Comparative Physiology and Biochemistry DOI:10.1002/jez.1055

Thursday, December 4, 2008

Species Profiles: The Flathead Chub

Threatened and Endangered species tend to fall into one of the following categories: Rare to the point where they are never seen, abundant in certain locations, or just damned hard to find. The Flathead Chub (Platygobio gracilis) falls into that first category. For example, some researchers at K-State have been sampling the Kansas River for most of the last three years. In 2007, they pulled out >36,000 fish, but didn’t find a single flathead chub (Eitzmann and Paukert 2007). Needless to say, this one is on the list of Kansas T&E species that I haven’t seen.

The flathead chub is a member of the minnow family (Cyprinidae), otherwise known as the largest family of freshwater fishes in the world (~286 species in N. America alone). Like most members of this family, flathead chubs are small (typically 9-16 cm). This species has a relatively broad, wedge-shaped head with long, sickle-shaped pectoral fins. Coloration is greenish or brown on top, with plain, silvery sides. The species was first described way back in 1836 (McPhail and Lindsey 1970), although the name has changed a lot (the genus flipped back and forth from Hybopsis to Platygobio a few times from 1950-1989, so you will see some references to H. gracilis here and there).

This species has occasionally been broken up into two subspecies: A large-river variety (H. gracilis gracilis; primarily the Missouri) and a smaller stream variety (H. gracilis gulonellus; primarily in the Ark River drainages). The transition zone between these two subspecies was Kansas, and the possibility of distinct genetic lineages was disputed (some people disagree with designating these as subspecies). That question will probably never be resolved due to the species’ afore-mentioned “rare to the point where they are never seen” status in Kansas.

The absence of this species isn’t terribly surprising, although that doesn’t make it somewhat depressing. Like the Pallid Sturgeon, the Paddlefish, the Chestnut Lamprey, and a ridiculous number of other fishes, the flathead chub has been eviscerated as a part of the natural community in large portions of its range by the construction of impoundments. The species occurs widely throughout North America, but is only endangered in the southern extent of its range (see the pretty map from Natureserve). The large rivers in the Missouri/Mississippi Drainage have been extensively regulated, thus wiping out avenues for upstream migration, and also reducing the productivity associated with flood events and backwater areas.

Meanwhile, less regulated areas of the flathead chub’s range continue to support viable populations. In Wyoming, the occurrence of the chub may be declining (Patton et al. 1998), but at least it is still out there. NatureServe actually lists them as being ‘secure’ throughout Colorado, Nebraska, Wyoming, Montana, South Dakota and much of Canada.

Little is known about the spawning habits of this species, although in Kansas most spawning occurs between July 1st and August 15th. As an agency, Kansas Department of Wildlife and Parks is supposed to have a recovery plan for this species, but as yet none has been written. I have a hard time imagining such a recover plan that didn’t include propagation efforts, and KDWP currently does not propagate any fish species for non-game purposes. At this point, the agency primarily protects this species by restricting activities in waters where the species potentially occurs (the Kansas and Arkansas Rivers) during the spawning period.

Want to read more about this species? I recommend this conservation assessment by Rahel and Thel (2007; pdf).

Lit cited:

Eitzmann, J.L. and C. Paukert. 2007. Annual performance report: Distribution and Abundance of fishes in the Kansas River.

McPhail, J.D. and C.D. Lindsey. 1970. Freshwater Fishes of Northwestern Canada and Alaska. Fisheries Research Board of Canada, Bulletin 173. Ottawa, Ontario, Canada.

Patton, T.M., F.J. Rahel, and W.A. Hubert. 1998. Using historical data to assess changes in Wyoming’s fish fauna. Conservation Biology 12:1120-1128.

Rahel, F.J. and L. A. Thel. 2004. Flathead Chub (Platygobio grcilis): A technical Conservation Assessment. Rocky Mountain Region, USDA Forest Service.