Friday, June 29, 2012

Why are garden tomatoes so much better than store bought tomatoes?

Nearly everything grown in the garden is better than store bought.  Somethings grown in the garden are so much better though there isn't really a comparison of the two.  Tomatoes are one such garden vegetable (or fruit!).  Of course, the garden produces vegetables that are only minutes old off of plants babied by the gardener and in optimal soil.  All this sets garden produce up for better taste over large scale farm produce shipped hundreds of miles to your local supermarket.  This is only part of the reason why garden grown tomatoes are so much better than store bought though.  Over many decades of tomato breeding programs, plant scientists have been able to produce tomatoes that store well and are firm enough to withstand the bumps and bruises of the shipping process.  The problem is this breeding process somehow "turned-off" the gene that produces the sweet garden fresh tomato taste found in common garden type tomatoes.  This type of problem is not isolated to tomatoes though.  Some modern roses, through years of breeding to produce a rose that withstands shipping and has fewer or no thorns lost their genetic ability to smell good.  So today, it is pretty common to find roses at the flower shop that have virtually no sent at all.  With researchers recently finding the taste gene that was turned-off in the tomato breeding process there is hope though that plant breeders will again be able to breed garden taste back into tomatoes.  There problems of turning off genes is also a good example of how genetics and breeding works.  You can selectively breed plants or animals in such a way to pick out specific traits such as large fruit, firmness, lack of thorns or so on.  The problem is that you can only do so much of this.  You can only breed tomatoes that are so big and then you can't breed them any larger.  There are limits to what plant breeding and genetics can do.  Corn, probably the most amazingly bred crop, has been bred to grow 15 feet tall.  The shortest varieties grow only two or so feet tall.  I don't think it would ever be genetically possible to produce a variety of corn that could grow 100 feet tall.  It trying to select for different traits other traits must decline to allow for the selected trait to be expressed increasingly.  That is exactly what has happened to tomatoes and roses.  As certain traits were selected for increasingly, other traits such as taste went by the wayside as the plant increasingly supported the selected for trait.

Monday, June 25, 2012

Life of a Cactus Part 9: Cactus Fruit and Seed

Ripe Prickly Pear Cactus fruit.
Within a month or so after flowering, the cactus flower ripens into a mature fruit ready to eat.  Some cacti produce dry fruits that simply break apart and scatter the seeds.  These dry fruits are typically dull brown and shriveled up.  Not much exciting about this type of fruit.  A large portion of cactus species though produce a brightly colored fruit swollen with sweet juicy pulp.  Often these juicy fruits are ripe for harvesting during the hottest driest part of summer.  May and June in in the Sonoran Desert are extremely hot and dry.  It is very common for not even a trace of rain to fall during these months and temperatures will often be in excess of 110 degrees towards the end of June.  During these months however some of the most abundant cacti produce their ripe fruit.  Buckhorn and Teddy Bear Cholla fruit ripens in May along with many species of Hedgehog Cacti.  In June then, Prickly Pears and Saguaros produce their fruits.  Depending on the species these fruits are typically red, yellow, or green.  While green fruit is not extremely attractive, red and yellow fruit brightly advertise their presence to all that pass by.   These brightly colored fruits are plump full of moisture in the otherwise bone dry landscape, making them even more attractive to animals in search of moisture.  These fruits are also often located of the tops of cactus plants where they will be most obvious.  The cactus, which is otherwise extremely conservative with water liberally gives out water to any animal that desires to brave the spines.  Many cacti, such as Saguaros, have very few spines on their fruits making them even more accessible.  This fruit is meant to be eaten.  So to make sure the fruit is eaten, the cactus makes a sweet, water rich fruit that is easily visible and accessible.  Birds and animals will often gorge themselves on these fruits.  These fruits may in-fact be their only water source during the hot dry late spring and summer months.  The cactus liberally shares its water with these animals, but not simply because the cactus has a sharing heart.  The cactus wants something in return for its water.  Each of these cactus fruits is loaded with dozens to even thousands of tiny cactus seeds.  Prickly Pears and Chollas have BB sized seeds that are as hard as rocks.  Other cacti such as the Saguaro have tiny black seeds.  These seeds are so abundant and so small in the cactus fruit, anything eating the fruit cannot avoid also eating the seeds.  While the fruit pulp is full of nutrition and water, the small seeds cannot be digested and pass through the entire digestive tract of an animal unharmed.  The digestive juices within the animals stomach cannot penetrate the seed coat and actually can help the seed germinate after passing through the animal.  This is exactly what the cactus wants in return from the animal that eats its fruit.  The cactus wants the animal to help distribute and aid the germination of the seeds.  Most often, the eater of cactus fruits and distributor of the seeds are birds.  After eating the fruit and seeds these birds will rest on branches of trees where the seeds will pass out of the body and be deposited on the ground.  Under the canopy of Mesquites, Palo Verdes, and Ironwoods is the ideal location for a cactus seed to germinate and grow into an adult cactus. This strategy helps ensure the survival of the next generation of cacti.
Ripe Saguaro Cactus fruit.

Friday, June 22, 2012

Corn: the Worlds Most Amazing Grain

Glass gem corn.  This variety of corn is an amazing testament of the incredible genetic flexibility and diversity of corn.
Corn, its one of the worlds most amazing cultivated plants.  It may be the worlds most amazing cultivated plant.  Corn was originally domesticated many thousands of years ago by ancient Mesoamericans in Mexico.  Scientists have endlessly debated how corn originated but still lack answers. There is no wild plant that is a direct relative to corn and it may be some sort of weird mutant or hybrid of wild species.  Corn has no ability to survive without human intervention and therefore cannot be a wild plant in anyway.  Both the husk and cob prevent corn seeds from being distributed on their own and depend on humans to remove the husk to expose the seeds, and then remove the seeds from the cob so they can be planted.  Corn and people go hand and hand.  Both corn and people benefit, and in a very real sense depend on one another.  The spread of corn throughout ancient North America supported many large civilizations and empires.  When Cortez brought corn to the Old World it rapidly spread throughout Europe supporting population growth and aiding the Renaissance and Industrial Revolution.  It is very likely that without corn, there would not have been enough food to support these great Western civilization movements.

What makes Corn so amazing?  A big part of it is corns amazing genetics.  Corn has the ability to be selectively bred to adapt to environmental conditions so it can be grown anywhere from the equator all the way to the Arctic Circle.  And all the way from rainforests to deserts.  No other crop matches this diversity and ability to be selectively bred to adapt to so many conditions.  Amazingly, none of these genetics were a result of, or even needed modern molecular bioscience.  Even more amazing, modern molecular bioscience has reduced the overall diversity of corn by over 90 percent according to many estimates.  So called modern corn varieties developed by science also are more dependent on fertilizer, irrigation, and pesticides.  On the positive side though, modern science developed corn is extremely productive.

So think about it.  Pretty much no matter where your ancestors came from they probably ate quite a bit of corn a long the way.  And if you think about your diet now, you probably eat quite a bit of corn today also.  We all are very dependent on the amazing legacy of corn and it is very likely that without corn we wouldn't be here today.  On the flip-side without us, corn wouldn't be here either.

Monday, June 18, 2012

Life of a Cactus Part 8: Flowers

Prickly Pear Cactus flower.
As you may deduct from above, if a cactus is ever to reach maturity, it must earn its way.  The cactus first puts years of effort into establishing itself in the harsh desert environment.  Drought, scorching sun, and relentless heat day after day are unforgiving.  Any violation of these harsh desert laws results in death.  Very few cacti survive much past the seedling stage and only those that are fortunate enough to land in ideal soil conditions during a good rainfall year will survive.  Those that do must grow and work to establish themselves as a strong young plant before even a single flower is produced.  Cacti that do flower are survivors to which few other plants are comparable.  Some cacti, such as prickly pears, can flower within a matter of several years after germination.  Others, such as the saguaro, require 35 to 40 years of growth and may be eight feet tall before a single flower is produced.  After the first year of flower production, those that continue to flower and produce seed year after year are even greater survivors.  It isn’t until young cacti grow from their seed however, that these cacti have truly beaten the brutal reality of natural selection in the desert environment.     
Hedgehog Cactus in bloom.
When it comes to cacti and reproduction, water again is central.  This time it’s a little different though.  The normally water conservative cactus becomes quite liberal with water use in flower and fruit production.  Many cacti produce very succulent, tender, and beautiful flowers containing lots of water.  If you were to touch the petals you would notice a slight succulence.  Then, touching the inside of the flower you would notice a slightly sticky dampness.   This is odd when compared to other typical desert plants that produce much drier and water conservative flowers.  So why would the cactus put so much water into flower production?  Why is it wasting this water?  If a cactus could talk it would probably say it is not wasting the water at all.  Rather, the wetness of the flower displays its heavy dependence as well as contribution to the animal world around it.  The cactus gives a little and takes a little.  In the form of nectar, the cactus flower provides both water and food for animals.  Bats, bees and other insects, as well as birds look to cacti as both a food and water source in the hot dry desert.  Often, the moisture found in a cactus flower is the most available source of hydration smaller desert animals can find at certain times of the year in the desert.  This water and food source often becomes a magnet for activity during flowering time.  The cactus flower can become a small swarm of buzzing insects looking for nourishment.  The cactus doesn’t just give out nectar just because it’s nice though, it does expect something in return.  When bugs, birds, and bats feed on cacti nectar, they also inadvertently pick-up pollen.  The pollen is then carried to the next cactus flower as the animal searches for more nectar.  In this way pollen is distributed from one flower to the next and pollination is accomplished.  Without bugs, birds, or bats carrying out this pollination cactus fruits and seeds would never form.  So the cactus gives a little and takes a little. 

Friday, June 15, 2012

Book Review 1491: new revelations of the Americas before Columbus

Charles Mann's book "1491: new revelations of the Americas before Columbus"has been around since 2005 and it has created quite a bit of excitement for historical buffs.  There have been a lot of reviews of this book, most of which center around the unknown history of the Americas prior to Columbus "finding" the New World in 1492.  I want to take a slightly different, and more biological, look at this book though.  Of course this is a great history book, but it is also a great science, specifically biology, book.  While much of the history contained within this book comes from historical eye witness accounts, a large portion also comes from scientists from the fields of archeology, epidemiology, genetics, botany, and others.  Reading this book will give you a good background and practical knowledge of these different fields.  Below are a few examples from the book.

Epidemiology: Very early on, when Europeans contacted the New World prior to 1500 or so, huge populations of Native Americans were found.  Populations were so dense that some early explorers found it impossible to settle.  A few decades later the population of Native Americans had decreased so significantly it became much easier to settle, for example the Pilgrims.  During the time period between first contact and settlement by Europeans up to 95 percent of Native Americans were wiped out by diseases Europeans introduced to the New World.  Diseases such as influenza, measles, and small pox, which Europeans were well adapted to, decimated the Native Americans.  There are several reasons for this including no prior exposure to the diseases, genetics, and ecological history of the North American continent.  The book goes in-depth into each of these areas to examine why Native Americans were affected so drastically.

Genetics:  Several sections of the book are devoted to genetics of natives to the Americas.  As mentioned before, the genetics of Native American immune systems is discussed and why this is partially responsible for susceptibility to disease.  Genetics are also examined to determine lineages of how North America was originally settled by Asians.  There is also a small section devoted to how a scientist is searching for descendants of an extinct people group by searching for there mitochondrial DNA in people alive today.

Botany and agriculture:  The history of corn is examined, which is quite an enigma.  Corn is one of the major contributions of the Americas to the rest of the world.  Other foods such as tomatoes, beans, potatoes, peanuts, peppers and squash were also completely unheard of in the Old World prior to contact with the new world.  It is odd to think of Africa without peanuts, Italy without corn or tomatoes, and norther Europe without potatoes.  This was the case though prior to the 1500's.

Overall, the book also gives you a decent idea of how science works.  While science obviously informs us about unknowns in the world, it also finds a lot more unknowns, questions and can often be inconclusive.  So, while this book gives an excellent history of North America is also is a pretty good science book.  Also on my reading list is Charles Mann's next book, "1493: Uncovering the New World Columbus Created."

Monday, June 11, 2012

Thomas Edison and Renewable Energy

Thomas Edison I am sure is one of the most interesting and influential Americans ever.  Everyone knows he invented the light bulb.  But he also had a number of other inventions, some of which were decades if not a whole century ahead of what the rest of the world was ready for.  For example, he was the first to invent a automatic electric vote-counting machine, which politicians thought would mess-up the entire democratic process.  Amazingly, most of Edison's education was self-taught.  He could not function well in traditional educational settings both because of his personality as well as being mostly deaf.  Edison, being the forward thinking and amazing inventor that he was, even foresaw problems we are having today with the environment.  Unfortunately, he was so ahead of his times that no one was able to really pick-up where he left off.  Him, being a father of modern electricity, it is amazing to see that he was able to think beyond extracting resources to produce electricity.  This was many decades before anyone seriously considered renewable energy as important or extraction of limited natural resources as a problem.  Here are some interesting quotes. 
“We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature’s inexhaustible sources of energy — sun, wind and tide…
“I’d put my money on the sun and solar energy. What a source of power!
“I hope we don’t have to wait until oil and coal run out before we tackle that.”
Thomas Edison, 1847-1931
Inventor of the incandescent light
Founder of Edison General Electric
Credited with 1,093 patents
  The picture, information, and quotes are from the above website.

Friday, June 8, 2012

Montezuma Castle National Monument: Montezuma's Well

Montezuma's Well, part of Montezuma Castle National Monument.  This is the well viewed from the cliffs surrounding the pond.
The Montazuma's Well portion of Montezuma Castle National Monument is the lesser known of the two sections of the park.  It has far fewer visitors every year, but I personally find this section far more interesting.  First of all, the "well" itself is pretty interesting.  This "well" is simply a hole in the ground pond, quite an unusual landscape feature and I know of nothing quite like it.  This pond is located on a hill top that caved in as water dissolved away the limestone bedrock forming the hill.  Nearly vertical cliffs line all sides of the pond and there are well over 100 stairs down into this hole along the trail.  Ancient Native American ruins are built into many of the cliff walls around the pond.  If you think about it, this would have been quite a nice place to live 1000 years ago or so.  At least compared to the surrounding desert.  The surrounding Upper Sonoran Desert is similar to what is found at the Montezuma Castle portion of the National Monument, however, it is slightly higher elevation.  This means it is slightly cooler and receives a little more rain, just enough to support Juniper trees in addition to all the other plants found in the desert we discussed in our previous post.  While Junipers do add another food source, a little more shade, and a source of materials, it still doesn't make living out in the open desert possible.  Within the "well" area, the pond moderates extreme temperatures, supports trees that provide shade, and provides water.  All this making for a nice place to live during ancient times.  Every time I have visited the well in the summer though, I still think it would be an unbearably hot place to live.   I have noticed the cliff walls where the ruins are located are considerably cooler though.  Hanging out in the cliff walls during the heat of the day was probably a major way ancient inhabitants avoided the heat. 
Montezuma's Well at the outlet, where the pond flows into one of the surrounding cliffs.
If you aren't at least sort of amazed just by the landscape structure of the well, than hopefully learning about the aquatic biology of the pond itself will amaze you.  The biology of the pond is truly weird, almost sci-fyish.  First of all, because the spring that feeds the pond come out of limestone there is a huge amount of carbon dioxide dissolved in the water.  This does not mean the water is poisonous, but does mean that fish cannot live in the pond.  Which would have been a bummer to me if I was an Native American living there 1000 years ago.  Algae, however, thrive on the abundance of carbon dioxide.  This algae supplies food to loads of amphipods, which are sort of like tiny freshwater shrimp.  At night time, huge numbers of non-blood sucking leaches migrate towards the surface to feed on the amphipods.  It is rather creepy imagining a mass migration of leaches swimming towards the surface. 
Vegetation along the canal the empties into Beaver Creek.
Once outside of the well, the trail also takes you down a cliff opposite the pond cliffs and along Beaver Creek.  This is actually my favorite section of the entire monument.  As mentioned before, water flowing out of the well flows into one of the cliffs surrounding the pond.  On the other side of the cliff, the water flows out of another cliff along the creek.  This water enters Beaver Creek in a truly beautiful desert oasis.  This area is very wet and shady.  Temperatures are far cooler here in the shade and thick vegetation.  Huge Sycamores and Ash trees fill the area.  The area has enough moisture to support beautiful Columbine flowers and even some poison ivy, so watch out.  This verdant green area is quite a refuge from the surrounding harsh desert landscape.  

Monday, June 4, 2012

Montezuma Castle National Monument

Montezuma's Castle
I recently made a trip to Montezuma Castle National Monument in central Arizona.  The National Monument is just a short trip off of the I-17 north of Phoenix and has two parts, the Montezuma Castle which is the main part, and Montezuma's Well which is a lesser visited section of the park.  Today, we will be discussing the castle portion of the monument.  We will discuss the well at a later time.  Both of these sections have some pretty interesting biology.  I will save some blog space by letting you read-up on the monument at the National Park website if you are interested:
Instead of giving the basic information on the park, I'll try to give you a little different perspective.
The tiny Beaver Creek that runs past Montezuma's Castle makes big changes in the desert landscape.  Much more water runs underground in this stream than above ground, feeding the trees of this desert oasis.
During the summer, Montezuma's Castle can give us modern humans a good perspective of what a desert oasis is like.  Us moderners are used to air conditioning, running water, and produce filled super markets everywhere we go.  Obviously this wasn't the case in the desert less than a century ago.  Hiking around the monument in the sweltering heat and scorching sun of summer should get one major point across to everyone about living in the desert.  That is: water is life.  The rolling limestone hills and mountains surrounding the monument are covered with relatively sparse Upper Sonoran Desert vegetation.  Water for drinking is completely absent and shade is minuscule.  Yuccas, prickly pear cacti, Creosote Bush, and Grey Thorn are the dominate plants, none of which cast any significant amount of shade.  Finding or not finding shade in the summer can mean life or death.  Think about how much hotter it is in the sun than it is in the shade.  Temperatures the weatherman gives us everyday are always taken in the shade.  If you were to take the temperature in the desert sun it might be thirty or more degrees hotter.  130 plus degrees is not easy for the body to handle and can quickly lead to life threatening heat stroke.  This is exactly why ancient Native Americans settled along Beaver Creek, where the water from the creek mean life.
Gazing up into an Arizona Sycamore tree along Beaver Creek in Montezuma Castle National Monument.  This tree casts life giving shade that decreases the temperature by tens of degrees.
Beaver Creek might not look like much, but its effect on the landscape is dramatic.  The water-less shade-less landscape surrounding Beaver Creek quickly is transformed into a more moist and shady habitat the nearer you get to the creek.  Real trees become abundant near the creek, replacing the diminutive pathetic excuses for trees further away.  Smaller desert trees such as Desert Willows, Mesquites, and Acacias, become common along the outer edges of the riparian area.  Riparian areas are simply the vegetation adjacent to water.  As you move closer huge Arizona Sycamores, Arizona Walnuts, Velvet Ash and Cottonwoods become abundant and cast a dense shade on the ground.  Hackberry, Mesquites, and Acacias are also common in the undergrowth of these large trees.  This shady more moist environment is far more hospitable and inviting than the surrounding desert.  In-fact, you can get the feeling this shady desert oasis might have even had a paradise like sense to it to ancient desert dwellers.  While the actual creek might not look like much, remember, a much large amount of water is flowing slowly underground.  This underground water feeds the deep rooted riparian trees tens of yards away, creating an abundance of life in the desert.

Beyond all this, the creek of course also supplied plenty of water for agriculture for ancient inhabitants.  The riparian vegetation also supplied the ancients with plenty of wild foods to eat such as mesquite bean pods.  Furthermore, the riparian area was not only attractive to humans but also to wildlife, which were hunted.  On our trip we saw an abundance of wildlife including two snakes, squirrels, wrens of various species and a rather tame Summer Tanager.  
A rather tame Summer Tanager found at the monument.

Friday, June 1, 2012

Life of a Cactus Part 7: The Cactus and Freezing Temperatures

All that water stored inside the cactus can be quite a problem certain times of the year.  Freezing temperatures can create ice crystals that burst cells causing tissue damage.  Depending on the amount of tissue that freezes and how well a cactus is adapted to freezing temperatures, freezing can actually kill a cactus.  Most species of cacti are not well adapted to freezing and for that reason most are tropical and subtropical.  Tropical climates never freeze while subtropical climates occasionally freeze.  The extreme southern United States, such as southern Arizona, Florida, and California are all subtropical.  The subtropical Sonoran Desert of Southern Arizona and Sonora, Mexico typically average freezing temperatures a few nights every year or fewer.  Freezing temperatures rarely last more than a few hours and results in the abundance of cacti found in the Sonoran Desert.   Saguaro cacti are the largest cacti that can tolerate freezing, but only as long as freezing temperatures last less than 24 hours.  Areas that receive freezes lasting longer than 24 hours have no saguaro cacti.  Organ Pipe cacti are much more frost sensitive and only survives along the U.S.-Mexico border in Arizona and further south.  Some species such as the Cordon can survive no freezing whatsoever and therefore only survive further south in Mexico.  A handful of prickly pears are able to survive very deep freezes for long durations of time.  Several species, such as Plains Prickly Pear, grow in grasslands of the central United States up to the Canadian border.  One species, Brittle Prickly Pear, grows nearly to the Arctic Circle surviving temperatures as cold as -40 degrees Fahrenheit.  Species able to endure freezing temperatures actually remove water from their cells, essentially dehydrating themselves, so ice crystals will not burst and kill cells.
Brittle Prickly Pear, able to survive temperatures of -40 degrees F by pumping water out of its cells so ice crystals do not burst cells.