Hawaiian Monk Seal (Monachus schauinslandi)
Ka'ena Point, Oahu
Archive for the 'Biology' category
A new life:
Laysan albatross (Phoebastria immutabilis) with very recently hatched chick.
Ka'ena Point, Oahu
29 January 2006
I've been going back through some pictures I took last month, trying to identify the birds in the pictures. I've found one gull that I'm having problems with. I've got a couple of shots I'm going to share with you, and then I'll give my current thoughts and reasoning.
The picture was taken on 23 Feb 09, on the grounds of Naval Air Station Pensacola. The gull on the right is the one I'm having difficulty with. The next picture is a closer view of that gull.
I am amusing myself with several little experiments; I have now got a little weed garden & am marking each seedling as it appears, to see at what time of life they suffer most.--
Letter to Joseph Hooker
21 March 1857
A few years ago, I was talking with one of my professors. We'd recently been at a seminar where a National Academy of Sciences member had presented some research. The research in question drew a number of good conclusions about the role of seawater chemistry on the history of life using an experimental setup that featured plastic cups arranged on cafeteria trays. The professor commented that the ability to design a "dinky little experiment" that could shed real light on enormously broad questions was the mark of the truly great scientists.
Over the summer, that comment popped back into my mind as I stood looking at a tiny patch of fenced-off ground in the middle of a bit of lawn.
Seed's got a video up on their website that outlines the entire history of life on earth. Go watch it. It's really cool, and it'll just take a minute.
An article published tonight in the journal PLoS ONE is forcing scientists to rethink everything they thought they knew about whale evolution.
OK. That's not actually true. But I've got a bet going that "someone" is going to use the phrase "rethink everything" in their story about this find, so better safe than sorry. Plus, it's a way cooler lede than "new whale fossil discovery matches predictions beautifully", even if the mundane description is the one that's just the tiniest bit more accurate.
Seriously, though, a multinational team of authors led by University of Michigan rock star Philip Gingerich is reporting a huge paleontological find - a fossilized pregnant early whale. It's the first time that an early cetacean has been found with a fetus. They also report finding the remains of a male of the same species. This combination of fossils - male, female, and fetus - is absolutely fantastic, because it provides information about so may different parts of the life history of this species.
Since one of the fossils found was a pregnant female, the researchers have named the new species Maiacetus inuus. The Maiacetus part of the name comes from the Greek for "mother whale". The inuus comes from the ancient Roman god Inuus, who was apparently the deity who handled (so to speak) sexual intercourse. That conjugation of names might be a bit unfortunate. It isn't as bad as some I've seen (Amorphophallus geei immediately springs to mind), but it does look like one possible translation of this whale's name would be "holy mother whale...
The fossils in question were found in 2000 and 2004, in an area of Pakistan that's already taught us a great deal of what we know about early whales. The newly-reported remains date to the early middle Eocene epoch (about 47.5 million years ago). This was a really interesting period in whale evolution, because it was a time when whales had not yet become fully marine organisms.
The skeleton of the male is the most complete of the three, and provides the best view of what the animal would have looked like while alive:
Artist's conception of male Maiacetus inuus with transparent overlay of skeleton. (Click to enlarge)
Credit: John Klausmeyer and Bonnie Miljour, University of Michigan Museums of Natural History
image courtesy of PLoS
There are certain organisms that you hear about a lot in evolutionary biology. In some cases, like Drosophila flies or E. coli bacteria, that's because the organisms are easy to use in experimental studies. Other organisms, like Hawaiian silversword plants or Galapagos finches, come up frequently because they're fantastic examples of evolution happening out in the "real world". And then there are those rare cases where an organism is both a fantastic example of evolution in the field, and a convenient organism to work with in more controlled circumstances. The three-spined stickleback (Gasterosteus aculeatus) is one of those doubly-convenient organisms.
There are populations of three-spined sticklebacks in the ocean and in many freshwater streams and ponds. The oceanic populations have been around for a long time, but the freshwater populations are all relatively recent in evolutionary terms - they're found in bodies of freshwater that were formed after the ice sheets retreated about 12,000 years ago. These populations appear to have evolved independently of each other, but they share a number of similar traits.
One of the more notable of the traits concerns the bony "armor" along the sides of the fish. The marine populations typically have a line of over 30 bony plates along their sides. The freshwater populations typically have only 6-9 of these plates. Why this is the case is a classic evolutionary biology question: do the freshwater populations lose the armor because there is a real advantage to losing the plates, or do they just lose them because there's no real disadvantage to losing them.
Casey Luskin cites a news story about a recent scientific paper to support his view that the loss of the armor is just the result of the freshwater populations not facing the selective pressure seen in the oceans:
(another own goal, of course.)
There he goes again. Creationist neurosurgeon Michael Egnor's latest post over at the Discovery Institute's Why's Everybody Always Picking On Me blog may have actually reached a new standard for missing the point. And, as both my loyal regular readers know, that's not an easy mark for Egnor to hit.
The current contender is his latest post in a back-and-forth that he's been having with PZ and Orac. Once again, Egnor is attempting to argue that evolutionary biology has not provided any useful insights to the field of medicine. That much is familiar ground. What's new this time is the hypothetical that he's dredged up in an attempt to prove his point. His hypothetical is long and involved, which should provide you with your first warning that the argument is perhaps not as sound as he believes:
What I'm arguing is that the truth or falsehood of Darwinian stories is of no tangible value to medicine. Consider the following example.
I would suspect that careful epidemiological studies of the British population would show that the prevalence and incidence of spina bifida increased following World War One. To my knowledge, this has not been investigated, but it would make sense if it were true, for the following reasons:
Britain suffered enormous casualties during the Great War, as did many other European nations. (I'm just using Britain as an example). It has been said, with asperity, that Britain lost a generation of men on the Western Front. Britain suffered 2,300,000 war casualties -- forty four percent of mobilized men, with 703,000 men killed in battle or by disease. On just one day -- July 1,1916 -- 19,240 British soldiers died in the battle of the Somme. The young men who died were the best of their generation -- healthy, and by definition capable of meeting the rigorous physical standards required for military service.
Of course, other British men with debilitating genetic disorders, such as men with spina bifida (which renders the afflicted congenitally paralyzed), were not in the trenches that day, because they were physically unfit for military service, or at least service on the front lines as infantrymen. It's safe to say that military age British men without spinal bifida were at greater risk of death in the war than were military age British men with spina bifida. Whatever the impediments faced by people with spina bifida -- and they face many impediments -- they were not called to serve and die in the trenches.
Spina bifida would then be a fine example of an environmental adaptation; it was protective against "acute lead poisoning" -- protective against being mowed down by German machine gun fire on the Western Front. So, assuming for argument's sake that my hypothesis about the post-war epidemiology of spina bifida is true, the genes that give rise to spina bifida conferred a selective advantage on young British men in the period 1914 to 1918, and the differential survival (and reproduction) of that age cohort would explain a (hypothetical) increase in the incidence and prevalence of spina bifida in England in the post war period.
Where to begin?
In Friday's picture quiz, I posted a picture that I took that contained two Hawaiian Monk seals (Monachus schauinslandi), and asked you to take a guess at what percent of the total population of the species appears in the picture. As David noted, if you're asking that sort of question, the answer isn't likely to be good. It certainly isn't good in this case.
The Hawaiian Monk Seal has been on the Endangered Species List since 1976. A five-year assessment of the seal's current situation was concluded in August, and examined whether or not the species has met the three biological factors required to change its status from "endangered" to "threatened":
1. Aggregate numbers exceed 2,900 total individuals in the NWHI;
2. At least 5 of the 6 main sub-populations in the NWHI are above 100 individuals, and the MHI population is above 500;
3. Survivorship of females in each subpopulation in the NWHI and MHI is high enough that, in conjunction with the birth rates in each subpopulation, the calculated population growth rate for each subpopulation is not negative.
[NWHI = Northwestern Hawaiian Islands; MHI = Main Hawaiian Islands]
As of the August review, the Hawaiian Monk Seals have met none of those three criteria. The population size continues to shrink, and extinction remains a very real threat.
Colin and qetzal both got the answer to the quiz question correct - the two individuals in Friday's picture represent a bit less than 0.2% of the total population of the species. David's answer (4%) wasn't too bad, either. The two seals that I photographed represent about 3% of the Main Hawaiian Island population.
I took the picture below at Ka'ena Point, Oahu in January of 2006. In this picture, there are two Hawaiian Monk Seals. (They can be hard to spot, so I've marked the two animals in a second version of the picture below the fold.) Here's the quiz question that goes with this image: without recourse to Google, estimate the percentage of the total population of the species that can be seen in this one picture.
(Click on the pictures to view larger versions.)