Wednesday, April 2, 2014

The Lord of the Fellowship of the Island Dwarves of the Lesser Sunda Islands

We've already talked about island dwarfism several times on the blog, with examples as varied as the Zanzibar leopard, the dwarf dinosaurs of HaČ›eg Island, and the Channel Island fox from Catalina Island.  But now is the time for something that is several times more epic.  Today, we are going to look at the wacky, crazy, and very odd sized animals that were native to the island of Flores in Indonesia as recently as 20,000 years ago!  And oddly enough, this paleoenvironment had many similarities with the fantasy world of Middle Earth in Lord of the Rings.  Don't believe me and want to learn more?  Well that, my friends, is known as a hook, a literary device used in the opening paragraph of a work of literature to grab the readers attention.  So if you're not hooked right now, then that's because you don't like fun.  The day may come when your courage to read my blog fails....but it is not this day.  At least I hope not.
A size comparison of the brave little Hobbit, the dwarf elephant Stegodon, the Komodo dragon, and the giant stork Leptoptilos robustus, drawn by the illustrious illustrator Zach Evens!
If you aren't already familiar with island dwarfism, here's a brief summary.  Oftentimes, populations of animals will become trapped on islands.  Over deep time, they can either evolve and adapt....or die.  On islands, what was beneficial on the mainland might not be quite as useful on a smaller, isolated chunk of land.  For example, if you are a larger animal, you are going to need more food than a smaller animal.  On the mainland, where food can be found in relative abundance, this usually isn't as much of an issue.  Furthermore, being large helps ward off predators, and can increase the likelihood of passing off your genes to subsequent generations.  So for some mainland animals, it pays to be bigger.
Lions tend to give elephants, especially full grown individuals, a healthy and respectful distance.  Photo Credit: traveladventuresbotswana.com
Now slow down and grab on to something solid.  Imagine a group of elephants becomes isolated from the mainland, and trapped on an island with limited food supply and other resources.  Now all of a sudden, its the larger elephants that are dying off, starving to death.  The biggest of the bunch are unable to find enough food for their regular breakfast (not to mention second breakfast or elevenses), and unable to pass on their genes.  Suddenly, being small is looking pretty good!  Furthermore, if the island that these elephants are trapped on has geographical features that ensure mainland predators shall not pass onto the island, then the smaller elephants aren't being removed from the gene pool by predators.  If you hit the gas pedal and speed up a few thousand years or so, you might get a population of cute little pint-sized elephants.  Which, as we have talked about before, does indeed happen, and has happened numerous times throughout history.
A fictional and somewhat inaccurate size comparison between many dwarf elephants and mammoths (pictured here a little smaller than they should be), and humans.  Photo Credit: withfriendship.com
So there's island dwarfism in a cute little nutshell.  This tiny little idea pertains to the island of Flores in a big way, as it potentially miniaturized a member of the human family tree!  Meet Homo floresiensis, nicknamed "the Hobbit" by its discoverers!  At only three and a half feet tall, this little guy would almost certainly be wasted at cross-country!  Initially announced in 2004, the discovery of at least six individuals of this cute little member of the human family tree have shown that this proto-human was not simply a genetic anomaly of this properly proportioned Pleistocene populace, but instead a participant in this posse of pint-sized people.
One small brained individual contemplates another.  The smaller skull is a cast of the skull of Homo floresiensis.  Photo Credit: Zach Evens
The evolutionary relationships of Homo floresiensis are still poorly understood, as different bits of the skeletal anatomy indicate different possible ancestors.  For example, brain shape, thick cranial bones, a short flat face, and a sloping forehead are features echoed in another early human, Homo erectus.  H. erectus does seem like a logical candidate for the ancestor of H. floresiensis, as H. erectus is thought to have inhabited southeast Asia as recently as half a million years ago.
An artistic and scientific reconstruction of Homo erectus.  Photo Credit: en.wikipedia.org
Other scientists believe that there is more to this hobbit than meets the eye.  Not everything matches terribly well with the "Insular Dwarfing of Homo erectus as an Explanation Regarding the Small Stature of Homo Floresiensis" hypothesis.  In proportion to the rest of the body, the brain does not typically dwarf nearly as much when it comes to island dwarfism.  However, the Hobbit's brain size did seem to decrease dramatically, a phenomenon not typically seen in island dwarfs, with the possible exceptions of the Myotragus cave goat and the Malagasy hippo Hippopotamus lemerlei.  Therefore, some scientists hypothesize that H. floresiensis is not actually a dwarf at all, but was instead a "living fossil," an informal term used to describe animals whose closest relatives are all extinct.*  In this other scenario, scientists suspect that H. floresiensis shouldn't even belong to the genus Homo, and instead is a descendant of Australopithecus, another genus of ancestral human, members of which are thought to have survived as recently as two million years ago.  If H. floresiensis was instead a living fossil, then an island might be the perfect place for this brave little halfling to find refuge.
A reconstruction of Australopithecus.  Photo Credit: pt.wikipedia.org
Besides dwarfism, islands can also serve as evolutionary holdout areas for animals that might not have been able to compete with other species on the mainland.  An excellent example of this is a member of the reptilian sphenodonts, lizard-like animals who can trace their evolutionary origins past that of lizards and snakes, all the way back to the Late Triassic Period, when dinosaurs were first evolving.  Today, the only place where you can find a living sphenodont, known colloquially as the tuatara, is on a number of small islands off the coast of New Zealand.  For whatever reason, this fascinating primitive reptile was unable to keep up with the rapid pace of evolution on the mainland, and found island life to be more its speed.  Unfortunately, introduced animals such as rats carry the potential to exterminate the tuatara within our lifetime.  With nowhere to go when the going gets tough, islands can be very dangerous places indeed.
The tuatara, a sphenodont holdout from a long forgotten age.  Photo Credit: www.ryanphotographic.com
Several lines of evidence support the idea of H. floresiensis actually being a descendant of Australopithecus, including morphological characteristics of the teeth and mandible, as well as the small brain size mentioned before.  A third hypothesis has been created to explain away the small size of this early human, which pertains to pathological conditions such as microcephaly, Laron Syndrome, and myxoedematous endemic hypothyroidism.  To read more about the support for and against these pathological conditions in regards to H. floresiensis, you can click HERE: this post goes ever on and on, and we still have a lot more ground to cover.  Besides, is it not strange that we should suffer so much fear and doubt over so small a being?  Such a little being.
Fossils can be tricksy things.  This is the type specimen of Homo floresiensis, LB1.  As you can see, there isn't a whole lot to go off of when trying to reach conclusions regarding the anatomy of this particular proto-human.  To confound matters further, only One Skull of Homo floresiensis has been discovered, which is the one you see in the photograph above.  Looks to me like LB1 has got that One Thing.  Photo Credit: Making Sense of the Small
A quality pic that shows a modern human skull on the left, and the skull of the Hobbit on the right.
"Boy, it sure would be easier to cover all of this ground if we could ride on the back of some giant elephant thing," thought an innovative member of the Haradrim people one day in Middle Earth.  Fortunately for this dreamer, he wasn't the only one who shared this vision.  The oliphaunts, giant relatives of elephants, were in no short supply, and were eventually made to carry large platforms on their backs.  Boy, that sure would be convenient if one of those dwarf elephants found their way onto Flores and got themselves shrunk, wouldn't it?  Well, lo and behold, meet Stegodon!  Although its mainland relatives were some of the largest proboscideans to ever evolve, a petite little version of Stegodon was endemic to the island of Flores at the same time the Hobbit was!
Bet you didn't see that one coming, now, did you?  Photo Credit: www.nature.com
You know what else would have been easier?  If Frodo had taken an eagle and flown over Mt. Doom, and dropped the Ring into the volcano.**  It would be a little TOO convenient for there to be a giant eagle that lived on the island of Flores and, unfortunately, this time you are correct.  There was, however, a gigantic relative of the modern day Marabou stork, Leptoptilos robustus, which measured in at an enormous 6 feet tall!  Since it was so large, some scientists suspect that this fool would not have been doing much flying.  Instead, this gigantic stork is thought to have stalked the Pleistocene landscape of Flores, living a primarily terrestrial lifestyle, most likely due to a lack of mammalian predators.  Kind of the opposite of island dwarfism: instead of big animals getting smaller, its small animals getting bigger!  Boy, that sure would suck if that gigantism happened to something gross like rats, wouldn't it?
An approximate size comparison between Leptoptilos robustus and Homo floresiensis.  Photo Credit: www.npr.org
So we've got hobbits.  We've got elephants.  We've even got giant birds.  Is there anything we're missing?  Sure there is: dragons.  Although there weren't any fire breathing dragons on Flores during the Pleistocene, there was a gigantic lizard that prowled the landscape!  Meet the Komodo dragon which, as luck would have it, is actually still alive today!  At ten feet long and weighing several hundred pounds, the Komodo dragon is the heaviest lizard alive today, and will take humans as prey if given the opportunity.  As a matter of fact, there has even been some speculation that the Komodo dragon evolved so large in order to hunt the dwarf Stegodon that also made their home on the island, but as far as I know this is simply speculation.
In this picture, you can see how big the Komodo dragon is compared to humans!  Photo Credit: imgarcade.com
Obviously, there is still a great deal that we need to learn about this ancient ecosystem, as well as about the individual species that were a part of said ecosystem.  Preciouusssssss fossils can be very difficult to find: unlike other inanimate objects, fossils don't really care one way or another if they are found by anyone, and just kind of sit there.  With any luck, in the coming years, paleontologists might discover evidence of humongous Floresian spiders, giant wolves, or intelligent trees.  Or maybe even elves.  Whatever the future holds, you can rest assured that I will be there to report on the new findings.  You have my word.

And my bow.

And my axe.



*Here on the blog, we've talked about animals such as the coelacanth and the horseshoe crab, both of whom are often referred to as living fossils.  In this context, I'm using the term loosely, as H. floresiensis is no longer alive today.  Instead, I am referring to the fact that at the time H. floresiensis was alive, it might have been considered a living fossil.

**If that didn't ruin that movie for you, keep in mind that Indiana Jones is irrelevant to the outcome of Raiders of the Lost Ark, and that Luke and Leia are siblings and made out.


Works Cited:

Wednesday, March 12, 2014

Eye Black: What Works for Football Players Works for the Cheetah

I remember when I was younger I would always wonder why baseball and football players wore black paint under their eyes.  My dad told me that the "eye black" was to help to reduce the glare that their eyes received from the sun.  Although some people seem to disagree whether or not this is effective for human sports players, it seems that several animals have evolved a similar pattern on their face!  But before we dive in, a very special thanks to Anne Price for her help with this post!
A football player takes a moment to appreciate the beauty behind the natural eye black of the prairie falcon.  Thanks, little man.  Photo Credit: www.nytimes.com
I imagine that there are a number of stories told by native peoples of Africa that explain the tear marks of the cheetah, which you can see in the picture above.  The one that I have heard before (which you can read by clicking HERE) tells of the cheetah being told by lions that she was not a cat, and instead was a dog.  The cheetah then went to talk with the wild dogs.  But the wild dogs also kicked the cheetah out, saying that she was a cat and not a dog.  The cheetah, sad with the fact that she did not seem to belong to either group, cried so much that the tear marks were burned into her face.
Some scientists believe that these black marks, which they called "malar stripes" or "malar marks," actually evolved to help the cheetah see in sunny conditions, by reducing glare and keeping the sun out of its eyes.  This would have been the original "eye black," a phenomenon whose roots extend back much further than the origins of baseball or football.  I was surprised when I was researching this natural eye black, as I thought it was a commonly cited fact that cheetahs had this eye black to reduce glare.  However, many of the sources just mentioned the malar stripes, and didn't actually address their function.  
In the book "Big Cat Diary: Cheetah," Jonathan and Angela Scott propose an alternative hypothesis.  Though they do mention the anti-glare hypothesis, the Scotts suspect that a more likely alternative is that the tear-marks serve to "accentuate facial expressions," which they say would be an "important consideration in social interactions with other cheetahs."  The tear marks, "along with the growls and hisses that are an important part of a cheetah's defensive repertoire," might "deter competitors from approaching."  While this is well and good for the cheetah, and is likely at least part of the reason why the cheetah has the malar stripes, I have a difficult time believing that this is the only reason why some animals evolved the stripes.  We will get to my reasoning in a second.
Photo Credit: Grace Albers
What I find really interesting about these stripes is that they are unique to the cheetah in the cat world.  The cheetah, as is mentioned in the African story above, is a very unique cat, different in many ways from others felines.  One way in which the cheetah is different is that it hunts primarily during the day, and is much less a nocturnal animal than most cats.  If you look at the eye of your house cat, look for two things.  The first is the size of the eye.  Though the cat is quite small compared to you, Mr. Whiskers has eyes that are only a bit smaller than yours!  Second, look at the pupils.  Unlike the pupils of humans that stay circular regardless of the level of dilation or constriction, cat pupils constrict to tiny diamond slits, but dilate to large circles.  This is because most cats are active at night and during the day, and in order to protect their eyes in a variety of light conditions, they have evolved very mobile pupils.  
My cat Chimney.  Notice her slit pupils.  And the One Direction pillow in the background.  Photo Credit: Dani Neher
The cheetah does not have diamond pupils, and instead has round pupils.  This stems from the fact that cheetahs are primarily diurnal, and usually hunt during the day.  According to the Scotts, "just like birds of prey," cheetahs have a "patch of highly light-sensitive cells on the retina known as the fovea."  These cells provide the cheetah with the "most precise visual perception," and enables them to "spot prey from as far away as 5 km (3 miles)."  I find this comparison to birds of prey interesting, as both the cheetah and the prairie falcon, another animal with malar stripes, would have the need to be able to spot prey from a great distance, and in sunny conditions.  This large North American falcon has very similar streaks of brown feathers beneath its eye, which flow down the face.  According to "The Prairie Falcon" by Stanley Anderson and John Squires, the "black mustachial stripes near the eyes...may further reduce glare."
This idea is supported by other bird of prey experts, such as Anne Price, the Curator of Raptors at the Raptor Education Foundation in Colorado.  Eager to learn more about the similar stripes on the face of the prairie falcon, I emailed Anne, and here's what she had to say:

It’s meant to reduce glare by having the sun strike or be concentrated in the area beneath the eye, leaving the area above in proper contrast.  The black lines under the eyes of cheetahs, most falcons (gyrfalcons and merlins being notable exceptions) and even flickers have malar stripes, though in flickers they serve as signals for courtship, not for better visibility of prey species!
Other falcons that have the malar stripe include the American kestrel....
....and the peregrine falcon.
Not all falcons have the malar stripe, however.  As Anne mentioned above, gyrfalcons and merlins are notable falcons that don't have the malar stripe, but here is another one: the African pygmy falcon, the smallest of the African raptors!  This is a picture that I took of one at the Denver Zoo.
Furthermore, the black streak under the eye is also seen on the face of many species that the cheetah preys upon.  According to the cheetah section in "Wild Cats of the World" by Mel and Fiona Sunquist, 91% of cheetah kills in the Serengeti are Thomson's gazelle.  In Kruger National Park, 68% of kills were the impala, and in other areas such as Botswana, springbok are an important part of the diet as well.  73.9% of the kills made by cheetahs in Nairobi National Park were Thomson's gazelle, Grant's gazelle, and impala.  As you can see in the pictures below, all of these antelope have that black streak under their eyes, though it is less pronounced in the Grant's gazelle and impala than it is in the Thomson's gazelle.  One of the biggest reasons for markings on an animal that don't aid in camouflage or sexual selection (i.e. differences between male and female that are used to attract a mate) is to help with species differentiation, so that they don't waste valuable time and resources attempting to breed with each other.  But since all of these antelope have the black tear marks, as well as both genders of the species, that's probably not the role that the tear marks were playing.*
A Thomson's gazelle.  Photo Credit: en.wikipedia.org
Grant's gazelle.  Photo Credit: en.wikipedia.org
Impala.  Photo Credit: animal-learn.wikispaces.com
A Cuvier's gazelle at the San Diego Zoo, which also has very similar malar stripes.
A Speke's gazelle at the San Diego Zoo, yet another gazelle that has the same sort of malar stripes.
It is these antelope that make me wonder whether the cheetah evolved the malar stripe to "accentuate facial expressions," as proposed by the Scotts.  In my experience, antelope such as the Thomson's gazelle don't really go around making faces at each other, at least nowhere near as much as cats do.  The fact that both the predator and prey in this scenario possess the same adaptation makes me wonder whether coevolution has occurred.
Coevolution is a biological phenomenon in which the evolution of one animal influences the evolution of another.  A classic example would be flowers and the insects that pollinate them.  Flowers need their pollen to be carried to other flowers in order for reproduction to occur.  Oftentimes, these flowers employ the use of bees and other insects to do the job for them.  But to make it worth their while, the flowers supply the insects with a delicious meal of nectar.  When the insects land to suck up the nectar, they also pick up some pollen.  Then, when they fly off to another flower to indulge in some more nectar, they unknowingly deposit some of the pollen, and simultaneously pick up some more!
A bee unwittingly pollinating a flower: check out the pollen attached to its leg!  Photo Credit: en.wikipedia.org
I find it possible that coevolution has occurred in regards to the cheetah and its prey.  Imagine if a certain lineage of cheetah evolved that had the black tear marks beneath their eyes, while the rest of their cheetah brethren did not have this black streak.  If the black streak did help them see their prey a little better by reducing glare, then perhaps these cheetahs were more successful hunters, and produced more offspring because of it.  Suddenly, the gazelles and impala are faced with a formidable foe that can suddenly see farther than they used to be able to.  In order to compensate, it's possible that the antelope who also had black streaks under their eyes were able to see farther as well, and spot the approach of a predator from a greater distance.  Strangely enough, I haven't been able to find anything anywhere suggesting that coevolution might have occurred here, so who knows!  I'm just throwing this out there, I'm not saying that's definitely what happened, but it's a prospect which I find intriguing and thought worth sharing with all of you.

*To read more about species differentiation and the role it plays in the success of biological organisms and species diversity, click HERE to learn more about the effects of logging on a type of fish called cichlids.

Works Cited:

An interview with Anne Price.

Anderson, Stanley H., and John R. Squires. The Prairie Falcon. University of Texas Press, 1997. (accessed December 16, 2013).

"General Information About the Cheetah." Cheetah Conservation Fund. http://www.cheetah.org/?nd=general_info (accessed December 16, 2013).

"How The Cheetah Got Its Tears." Cheetah Conservation Fund. http://www.cheetah.org/?nd=story_cheetah_tears (accessed December 16, 2013).

Stokes, Donald, and Lillian Stokes. The Stokes Field Guide to the Birds of North America. New York: Little, Brown and Company, 2010. (accessed January 23, 2014).

Wednesday, February 19, 2014

Colorado Raptors of Winter: An Interview With Anne Price

You guys have heard of Anne Price from the Raptor Education Foundation (REF) before: she's the one who brings all of the awesome birds of prey to the raptor shows at the Best Western Denver Southwest dinosaur hotel!  Eager to learn more about some of the raptors that live here in Colorado during the winter, and how the change in weather affects the birds behavior!  She was nice enough to oblige, and the answers were definitely very interesting!  So after you check out the REF website HERE and like their Facebook page HERE, please join me in welcoming Anne Price, Curator of Raptors at the Raptor Education Foundation!
Anne Price with a prairie falcon at the Best Western Denver Southwest!
1. What raptors are you likely to see if you live along the Front Range here in Colorado?

The big four hawks are: red-tailed hawk (year round), Swainson’s hawk (April through early October), rough-legged hawk (October through March), and Ferruginous hawk (year round, but rare on front range in summer months).  Turkey vultures in spring, bald eagles in winter, golden eagles, Cooper’s hawks and American kestrels year-round, turkey vultures and osprey from March through October.  There are more species around but these are the most likely to be seen by the average birder.
A red-tailed hawk at another one of the raptor shows at the Best Western!
2. What raptors have migrated away that you would be able to see along the Front Range during the summer?

Turkey vultures and Swainson’s hawks.
Anne Price holding a turkey vulture!
3. What special behavior, such as courtship rituals or other behaviors like that, can you observe in raptors during December and January along the Front Range?

You may see red-tailed hawks and bald eagles start to sit next to each other in trees or along telephone poles. The big excitement comes from great-horned owls, which will begin courtship calling (hooting back and forth) in the middle of the night, starting around Christmas Day.
Anne holding a great-horned owl!
4. Do the raptors at the REF change their behavior at all during the winter? If so, how do they change?

Our birds eat more, so we feed them more to put on just a bit more fat for the cold weather. Our two Swainson’s hawks get feisty and start stealing food because their metabolism is telling them that they need to bulk up for a long migration ahead. I always let them gain 1-3 oz during this transition so they are ready for the cold, which came early this year and was REALLY cold. Our female golden eagle will also start gaining weight and developing a brood patch as she gets ready to lay her eggs in early March. She has gained 9 oz just in the last 2 weeks!
A golden eagle takes flight in Dinosaur National Monument!
5.  Finally, I remember you mentioning the black streaks under the eyes of the prairie falcon as a glare reducing adaptation. What can you tell me about that?

It’s called the “malar stripe” or “malar mark.” It’s meant to reduce glare by having the sun strike or be concentrated in the area beneath the eye, leaving the area above in proper contrast. These are black or dark lines under the eyes of cheetahs, most falcons (gyrfalcons and merlins being notable exceptions).  Even flickers have malar stripes, though in these birds they serve as signals for courtship, not for better visibility of prey species!

Which is why the Rockies and the Broncos do the same thing…….
A REF prairie falcon at the Best Western!
Thank you so much Anne for taking the time out of your schedule to answer some of our questions!  I know I will definitely be on the lookout for these birds in the upcoming weeks, and hopefully everyone else will be, too!  Make sure to check out the REF Facebook page HERE, as well as their website HERE.  You can also come visit all the REF birds on Saturday, April 12 from 11am to 2pm! Admission is free and there will be giveaways and refreshments.  RSVPs are kindly requested; please visit http://www.usaref.org/OpenHouse.htm.  Thanks again, and keep an eye out for a follow-up post regarding those fascinating malar marks!

Monday, February 3, 2014

Pictures of my Animals From My New Camera!

For Christmas I got a new camera, a Canon EOS Rebel! I have a ton of awesome pictures that I want to share, including pictures of my pets, some astrophotography, and more!  First, I am going to share some pictures of some of my various critters!  To see some higher quality versions of some of these pictures, check out my Flickr by clicking HERE!  First off, some shots of my beagle-basset dog, Daisy!
My mom with Daisy!
Next up are some pictures of my chubby kitty, Chimney!
Up next are some of my other pets, such as Juan Priestly the betta fish!  I have two, a delta tail and a veil tail, and I can't remember for certain which one is which.
In another tank I have two African dwarf frogs (Hymenochirus boettgeri), and this is the new one I got just a few days ago!  I named after the bright star Aldebaran in the Zodiac constellation of Taurus the Bull!
In the same tank, I also have a snail.  Petco (where the pets go) says that it is a gold Inca snail (Pomacea bridgesii).  However, that scientific name seems connected to a snail that is colloquially called the mystery snail, so I'm not entirely certain what this snail is.  So I suppose the name "mystery snail" truly does seem appropriate!  Anyways, I named him Liam, after Liam Payne in the fantastic band One Direction.  This is what I do to people I like, I name snails after them.  Maybe next time I will upload a picture of my other snail, Zayn Malik.
Second to last, here is a picture of Wolverine, my baby California kingsnake!
Finally, here is a picture of someone who is not my pet, and is actually a pet of some friends of mine, Isabel and Sam Lippincott!  This is their dog Louis, who was actually attacked by a coyote.  He is fine now, and is going to make a full recovery!
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