Category Archives: Animals

Lactococcus is here to stay!

There was a great story recently on National Public Radio about the Wisconsin state legislature passing a bill to name the first state microbe: Lactococcus lactis.

States commonly have a state flower, animal, bird, song, even a state dance, but this is thought to be the first time that a state has named an official microbe.

Lactococcus are cocci bacterium, which means that the individual bacterial cells have a circular shape. Cocci bacteria species can be solitary or they can cluster together. If they group, they can form chains like little pearl necklaces or bunches like grapes. Lactococcus groups in pairs and short chains.

This bacterium has been important in human culture because it thrives on milk sugars (lactose), using the sugar as energy and producing a waste product of lactic acid. Normally this might be a bad thing, but some prehistoric culinary genius discovered that not all was lost if her milk was spoiled by this bug.

By producing lactic acid as part of its digestive activities, the pH of the milk was lowered (becoming more acidic) which causes the milk proteins to curdle, or clump together, thus separating the curd from the whey (the part of the milk that stays liquid). A similar result can be obtained by adding other acids to the milk, such as stomach acid, and it may be that the first curdling was done when milk was stored in a bag made of an animal stomach.

However it happens, separating the solids out of the milk is almost always the first step in the production of cheese. From this step different ingredients are added to make the wide variety of cheeses that we enjoy today.

So it makes since that the Wisconsin legislature recognized the importance of this little “bug” to their state’s economy. In fact, as pointed out by Elio Schaechter of the microbe blog Small Things Considered, we could live without the state animals, but we really could not live our lives without the microbes.

NPR invites people to auggest other appropriate state microbes. You can put your vote in at NPR (include microbe in the subject line of your email). Leave your vote here too. Which microbe is most important to your region?

Polar Bear populations

In an earlier post about the effects of climate change I made the point that there is a lack of intellectual honesty in the political climate change debate and a comment on that article provides a perfect example.

The commenter quoted an opinion piece by Gerald Warner. Mr. Warner cites population estimates by the International Union for Conservation of Nature (IUCN) Polar Bear Specialist Group that summarizes 19 sub-populations of bears. The summary of the population status is that 8 are declining, 3 are stable, 1 is increasing, and the other 7 are unknown. They currently estimate a world population of approximately 25,000 individuals. (See the footnote)

The most flagrant claim made by Mr. Warner is “the actual statistics” that since 1970 polar bear population has quintupled from 5,000 to an estimated 25,000 individuals.

A quick search revealed an article by Terence Jeffrey that gives at least partial references for “the actual statistics.” In his article, Jeffrey relates a history of scientific polar bear population estimates over the last five decades. An honest reading of his article shows that less was known early on and with increased efforts made to study polar bear numbers, we have better estimates now. Who would have guessed?

Quoting from Jeffrey, in 1965 world population of polar bears was estimated to be “5,000 to 8,000 animals,” “over 10,000” or “17,000 to 19,000 animals.” So, the apparent basis of “the actual statistics” of Mr. Warner comes from the extreme lowest estimate of bear populations in the 1960s to the estimate of the modern populations to get a quintupling. I am not sure in which universe this counts as “actual statistics.”

All of this clearly demonstrates one of the main points I made in the earlier story—the dishonest manipulation of scientific information for the express purpose of confounding the public is all too common in the political debate of climate. I am afraid it is only going to get worse, and my stated hope for intellectual honesty in politics is looking less likely all the time.

International Union for Conservation of Nature (IUCN) Polar Bear Specialist Group. http://pbsg.npolar.no/en/index.html

Jeffrey, T. 2008. The great polar bear population puzzle. http://www.humanevents.com/article.php?id=26627

Warner, G. 2010. Climategate: two more bricks fall out of the wall of deceit—rainforests and polar bears. http://blogs.telegraph.co.uk/news/geraldwarner/100030204/climategate-two-more-bricks-fall-out-of-the-ipcc-wall-of-deceit-rainforests-and-polar-bears/

Footnote: I wanted to examine the trends in the known population numbers a bit more as given by the IUCN, so here are some observations. Of the 19 sub-populations, they currently estimate the population of 14 and declare a status for 12 of them. By taking an average of the high and low population estimate for each of the given areas, the sum is 18,461.5 bears. This is the sum of the averages for all the estimated areas. There are 5 areas with un-estimated populations, so there are more bears in the world. Plus, the average may not be the best estimate for each area and is no doubt low for some areas and high for others. So, a total global estimate of 25,000 is reasonable enough.

If we sum the estimated populations by status (declining, increasing, stable, and unknown) we see that 52% of the known population is classed as declining; 2% are classed as increasing; 19% are classed as stable; and 28% have an unknown status.

So, over half the known population of polar bears are in declining populations. More than a quarter are unknown as to their population status. Almost 20% appear at this time to be stable in population numbers, and 2% seem to be increasing. I fail to see how anyone could construe these data to say that “polar bears appear to thrive on warming” (quote from Warner).

Sore-mouthed dinosaurs

Benjamin Franklin quipped that the only thing in this world that is certain is death and taxes. He could have added disease to that list too.

There is a growing body of evidence that many of the diseases that humans and animals suffer from have followed us around from our earliest evolutionary roots. And recognizing disease in fossil animals can tell us a great deal about how the animals lived and give us insight into their everyday lives.

Take for example the well-known dinosaur specimen popularly called “Sue,” one of the most complete Tyrannosaur rex specimens known. Casts of its skeleton have been traveling to museums for many years in the exhibit “A T. rex named Sue,” amazing many people with its size and majesty. In the last weeks of Sue’s life she may have been a very cranky Dame indeed.

Upon viewing her skeleton, many have noticed the unusual holes along her left jaw. Those holes are not normal, but where they a sign of trauma, like wounds from combat? Turns out they are likely from a much small foe than another T. rex.

Left jaw of the dinosaur Sue showing pathologic holes

Left jaw of the dinosaur Sue showing pathologic holes

In a recent article (Wolff et al., 2009) researchers suspect that Sue, and other large carnivorous dinosaurs like her, were plagued by an infection of something like Trichomonas gallinae, a pear-shaped protozoan parasite that today infects birds. The parasite lives in the upper digestive tract of many bird species and causes sores in the mouth and throat. Some of the sores in modern birds have caused bone erosion that looks just like that seen in Sue.

Modern birds transmit the disease through discharge of body fluids. (This parasite does not attack humans). Adult birds that feed offspring can infect them directly for example. Infection is very common in modern birds, and infected birds may have no ill effects. It is not unlikely that in 65 million years of coevolution modern birds have built up resistance to the disease that their ancient cousins, the meat-eating dinosaurs, did not have.

It appears that Sue, and others like her, died of simple starvation, not being able to eat because of mouth and throat sores. An ignoble end perhaps, but showing that this thing we call life can change on the smallest circumstances.

WOLFF, E. D. S., S. W. SALISBURY, J. R. HORNER, AND D. J. VARRICCHIO. 2009. Common Avian Infection Plagued the Tyrant Dinosaurs. Plos One, 4(9):e7288.

Other dinosaur facts can be found here at Boneblogger. Search or select the category for more.

Musk ox say no to hunting

As we face the uncertain effects of climate change ourselves in the future it is instructive to look back in time to see how other species fared. (See also a geologic perspective on the effects of climate change.) Paleontology is one of the main sciences involved in this research and so proves to be very relevant to this modern issue.

A recurring mystery in paleontology is the cause of the most recent major extinction event at the end of the Pleistocene or Ice Age. Many large species of mammals, collectively referred to as megafauna, became extinct relatively recently, a mere 10,000 years ago more or less. Charismatic animals such as mammoths, mastodons, giant ground sloths, and saber toothed cats vanished from the Earth forever.

It has long been debated what the primary cause of this extinction event was. Just as with other major extinctions observed in the fossil record, there are a number of suspected causes for Ice Age extinctions: disease, climate changes, and extra-terrestrial phenomena like asteroids. But the Ice Age extinctions have another factor that previous extinction events do not have—the emergence of humans as a major player upon the landscape. Did human activities, maybe the over hunting of the megafauna, drive them to extinction?

Many studies have tried to get at this question, but it is very difficult to separate all the confounding issues from each other to focus on just one to test its potential effects. A new study however was able to do just this.

In a recent paper (Campos et al., 2010) DNA material was extracted and analyzed from one of the species that did survive the Ice Age extinctions, the musk oxen. This Ice Age relic lives today mainly in the high-latitudes of Greenland and Canada, but was once more wide-spread. Indeed, its remains have even found as far south as Nebraska, New York, and Ohio during the Pleistocene.

Musk oxen are well adapted to the extremes of arctic living with sturdy bodies and thick coats of hair.

Musk oxen are well adapted to the extremes of arctic living with sturdy bodies and thick coats of hair.

The researchers collected samples from across the musk oxen’s former range for the last 60,000 years. They examined the DNA to look for patterns of population dynamics over that period. Basically, when a population is strong and has many members the DNA samples show an increase in diversity—more genetic variation in the mix. When populations suffer and numbers decrease the results show up in the DNA as a decrease in diversity, sometimes referred to as a genetic bottleneck. So, the DNA diversity over time shows a proxy for population numbers and health.

Therefore, if humans were a prime driver of population declines for musk oxen at the end of the Ice Age we would expect to see genetic bottlenecks within the DNA corresponding to the timing of human activity within the musk oxen’s range.

The DNA results show that the geographic origin of all the musk oxen DNA is northeast Siberia with a large diverse population. However, the population in that region crashed about 45,000 years ago. After that population decline, there was a world-wide genetic diversity increase about 30,000 years, followed by another decline about 18,000 years ago, and finally a slight recovery about 5,000 years to the modern relict populations.

With these data we can directly test for the first time the correlation of population declines of the musk ox with human activity. And, in fact, they do not correlate very well, suggesting that humans played little role in the population dynamics of musk oxen.

So, if not humans, what then was driving the populations to decline?  The most likely cause was environmental changes, particularly climate changes. The Pleistocene is characterized by shifts in climate patterns with the best-known effect being glacial advance and retreat over the last 2 million years. It seems, at least in the case of musk oxen populations, that the pattern of boom and bust was driven by their ability to adapt to climatic changes in their environment. Musk oxen almost went the way of the mammoths and succumbed fully to extinction, but managed to just hold on by their horns in greatly reduced numbers until today.

Of course, whether they, or any other species that are similarly at risk, will weather the next several decades, and any modern climate changes, remains to be seen. The effects of climate change may well prove to be too much for them after all.

CAMPOS, P. F., E. WILLERSLEV, A. SHER, L. ORLANDO, E. AXELSSON, A. TIKHONOV, K. AARIS-SØRENSEN, A. D. GREENWOOD, R.-D. KAHLKE, P. KOSINTSEV, T. KRAKHMALNAYA, T. KUZNETSOVA, P. LEMEY, R. MACPHEE, C. A. NORRIS, K. SHEPHERD, M. A. SUCHARD, G. D. ZAZULA, B. SHAPIRO, AND M. T. P. GILBERT. 2010. Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. Proceeding of the National Academy of Sciences.

Keep Your Cichlids Healthy – It’s Easy

Guest Post

The hobby of keeping cichlids can be a very enjoyable and rewarding experience. Most people just getting started in keeping these very intelligent aquarium fish have lots of questions. Even as an experienced aquarist, I seem to learn something new everyday. Here are some tips to get you started.

The first thing that you need to do when keeping cichlids is to consider what size that your cichlids will be when they are fully mature. If you have gotten bitten by the Oscar bug and have fallen in love with these very personable fish, you are simply going to need a large tank.

Most people will recommend at least a 55 gallon aquarium to keep a pair of Oscar fish. That is simply the bare minimum for these big guys. If you have a smaller variety, you just need a smaller tank. Simple, right?

Second, ph level and water salinity, among other water chemistry levels, can be very different between the different types of cichlids. Just consider African Cichlids. They are found in different lakes in Africa. Each of these lakes have their own unique water chemistry, so if you are keeping Africans, it is very important to do your research if you are going to replicate their native habitat.

If your cichlids are going to thrive, whether they are African or New World Cichlids, temperature and water chemistry must be monitored.

Plants and cichlids sometimes just do not match well. Many cichlids are very intelligent, but they love to make lettuce out aquarim plants. Its a challenge, but it can be done.

American varieties of cichlids seem to be able to tolerate plants in their aquarium better that Africans do. But having made that point, Oscars love to destroy plant life. Angel fish, on the other hand, seem to tolerate plants very well.

Angel fish can be some of the most enjoyable cichlids in my opinion. They even do very well in community tanks because they are generally docile and tolerate plants very well.

Visit cichlid care to learn how to keep cichlids healthy, colorful and happy. And visit keeping cichlids to learn how to keep your cichlids stress free.