Did You Know (40)?

The Rocky Mountain goat (Oreamnos americanus) may be as much antelope as it is goat. Mountain goats belong to an order of even-toed ungulates known as Artiodactyla. This large mammalian group includes antelopes, gazelles, cattle, muskox and true goats. Classified within the subfamily Caprinae or goat-antelopes, the mountain goat is the only member of the genus Oreamnos. The evolutionary history of this species is unclear, making the mountain goat a classic example of a ‘rogue taxon.’ Various DNA comparisons fail to link mountain goats with any one extant (living) Caprinae species thus suggesting that it is basal within its group. This distinction makes the mountain goat truly unique member of its biological family.

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Did You Know (39)?

The windchill temperature is a relative value based on evaporative cooling. Much like the chill felt following a hot shower, a moderate breeze can transform a cold day into dangerously frigid conditions. The flow of air over exposed skin increases heat loss as vaporization “steals” body heat. In contrast to skin, a moisture free inanimate object will take on the temperature of its surroundings regardless of the ambient wind velocity. It is for this reason it can be 5℉ (-15℃) and feel like -13℉ (-26℃) at the same moment in time.

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Did You Know (38)?

Biodiversity is the scientific way of describing variety; it is a measure of the total number of distinct species in a defined area. Some biologists assess biodiversity by examining genes within a population, while others invoke the classical “species concept” as a way of defining the species richness of an ecosystem. Regardless of the measurement tool, high biodiversity is a good thing and is cited as a positive indicator for environmental health. 

Costa Rica and its tropical forests are known for its high species richness. Some regard the entire country as an ecological hotspot. With the Atlantic Ocean to the east and Pacific to the west, two distinct weather systems collide where the mountains bisect the country. Traveling east to west, the elevation increases along the Caribbean slope. The cumulative affect of oceanic air and elevation changes result in the formation of distinct microclimates that define multiple ecosystems within small patches of land. Like the Caribbean, the Pacific Slope is geologically diverse. As the mountains sink towards the ocean, the structure and diversity of the forests change. Geographic diversity and climate stability contribute to the staggering biological variety found across the country.

Recent research suggest that scientists have underestimated the diversity of life on the planet. Specifically, Genoveva Rodriguez-Castaneda found that tropical insect diversity increases with increasing elevation1. Montane forests are defined by plant species that have adapted to narrow geographic and climactic conditions. Each valley or hill creates a microclimate that defines a distinct ecotone (ecotone: transition zone between habitats). As environmental characteristics become increasingly narrow, so do the characteristics of a given niche. These narrowly defined niches promote specialization and diversification. As a result of these observations, scientists now project that there may be six times more insect species than previously suggested.  

The sloth-like Megalopygidae larvae pictured here is an embryonic crinkle or flannel moth species. Megalopygidae species can be found in North America and the Neotropics. The larva are often called Puss Caterpillars and have venomous spines that, when touched, can produce a variety of symptoms. In addition to pain and inflammation, a sting can cause headaches, nausea and shock2. This individual was found in a secondary tropical forest within Costa Rica’s Caribbean Slope. 

• Genoveva Rodríguez-Castañeda, Lee A. Dyer, Gunnar Brehm, Heidi Connahs, Rebecca E. Forkner, Thomas R. Walla. LETTER: Tropical forests are not flat: how mountains affect herbivore diversity. Ecology Letters, 2010 
• "Megalopygidae." Wikipedia. Wikimedia Foundation, n.d. Web. 15 Feb. 2015.

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Did You Know (37)?

When Mormon settlers crossed the Mojave in the mid-19th century they "saw" the hands of Joshua reaching towards the heavens... so goes the origin of this tree's colloquial name. Joshua Trees (Yucca brevifolia) are a tree-like monocot plant that belong to the family Agavaceae. Although they are not true trees that produce growth rings with a woody core, this top heavy plant stretches nearly eleven meters towards the desert sky. The asymmetric branching and long spiky leaves remind me of the lonely acacias that dot vast stretches of the African savanna. Restricted to an altitude of 400 to 1800 meters, Joshua trees are an icon of the high desert. Their survival is contingent on adapting to the arid environment, and the plant's morphology reflects its evolution. A long taproot that seeks deep pockets of water, waxy leaves that prevent desiccation, and reproduction timed to ephemeral rains are an adaptive response to life in the desert. Following a heavy precipitation event, large clusters of fragrant white flowers (panicles) emerge and await their pollination. The pollinator is an obligate symbiont known as the pronuda yucca moth. Female moths will deposit eggs into the panicle and, in doing so, cross pollinate the trees. Larval moths feed on developing seeds and will emerge following metamorphosis. The yucca moth and Joshua tree coexist in a mutualistic relationship in which both the moth and tree benefit from their codependency.  

* Did You Know #37 is a modification of a blog that I first posted on April 9, 2011

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Did You Know (36)?

A giraffe’s neck has only seven cervical vertebrae. Surprisingly, this is the same number of vertebral bones in most mammalian necks. The 1.8 meter (6 feet) climb from shoulder to head requires an unusually powerful heart muscle. Weighing in at 11 kilogram (25 pound) the massive heart relies on a series of one-way arterial valves to propel the blood uphill. This tallest of all living land mammals has extreme metabolic requisites that has led to the evolution of a lung capacity that can capture 55 liters (12 gallons) of air. 

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Did You Know (35)?

On this February 12, 2015 it would be fitting to consider the accomplishments of the great thinker, scholar and scientist who revolutionized modern biology. Today, as with every February 12th since 1809, is Charles Robert Darwin’s birthday. Best known for writing “On the Origin of Species by Means of Natural Selection,” Darwin describes a mechanism for evolutionary change and supports his ideas with observations of the living, extinct and biogeographical record. This much acclaimed and equally reviled text fundamentally changed the way we interpret and understand the living world today. However, Darwin was much more than a biologist and naturalist. Before he ever pondered his revolutionary idea, Darwin was a geologist. 

The importance of Charles Lyell’s book “Principles of Geology,”  is a well established historical footnote in the retelling of Darwin’s story, however few know that Darwin devoted much of his time and research to understanding geologic change. As a result of his five years on the H.M.S Beagle, Darwin gave lectures on the geology of the Andes, published papers about the fossil record, and authored multiple books about the geology he observed. In fact, the famed journal written during the voyage on the Beagle included 1,383 pages about geology and only 368 pages about plants and animals. Before Darwin ever published his theory of evolution by natural selection, he wrote two books on volcanology and a book on the geology of the Falkland Islands. The love affair with geology ended by 1840, but it is clear that Darwin’s immersion in the topic was fundamental to developing the biological theory which unifies the patterns we see throughout life on this planet.  

http://blogs.scientificamerican.com/history-of-geology/2012/02/12/darwin-the-geologist/

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Did You Know (34)?

While the exact number is debatable, there are between 325 and 340 hummingbird species. Globally restricted to the Americas, Ecuador is the king of hummingbird diversity with its 132 confirmed varieties. At 5 cm and the mass of a U.S. penny, the Cuban bee hummingbird (Mellisuga helenae) is the smallest avian species alive today. Although little, hummingbirds are not inconspicuous animals. Males fearlessly flash iridescent colors around the neck in what is known as the gorget display. Revealing bright hues of red, green and blue, such displays are aggressive messages that denote breeding and feeding territories. Despite their diminutive size, hummingbirds will dive-bomb conspecifics as well as invading species that compete for their food and space. Survival for a hummingbird is all about energy conservation. With wingbeats of 50 beats per second during a hover and 200 beats per second on an attack, these birds drain their fuel like a HUMMER H2 climbing a steep hill. Daytime heart rates can exceed 1000 beats per minute in order to sustain the high oxygen and nutrient demands of wing muscles. This intense activity requires an energy rich diet, which explains why the typical hummingbird needs to consume a greater nectar mass per day than its own body mass. At night hummingbirds “shut down.” Referred to as torpor, the body enters a hypothermic state as it drops nearly 20o C and the heart rate falls to between 50 and 180 beats per minute. Even with these energy saving measures, hummingbirds still lose 10% of their total body weight each night. Underscoring these high energy demands is the fact that some species like the ruby-throated hummingbird (Archilochus colubris) will migrate from Central America to northern Ontario, Canada.

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Did You Know (33)?

The only land mammals larger than rhinoceros are the African and Indian elephants. Restricted to Asia and Africa, the five remaining rhinoceros species are among the most critically endangered mammals on the planet. A 2013 population census counted fewer than 30,000 wild individuals. A sub-species of the white rhinoceros (Ceratotherium simum cottoni) has the dubious distinction of having the fewest living representatives. The remaining 6 northern white rhino’s is heavily protected, some of which have had their horns filed down. As a species, the white rhinoceros (Ceratotherium simum simum) has the largest global population of all rhinos, however their horn continues to be a tempting lure for poachers. While Africa’s combined rhino population consists of nearly 26,000 animals, Asia now has less than 3500. The Sumatran rhinoceros population is believed to be consist of nearly 100 individuals, while the Javan rhino is approaching global extinction with its meager population of 35-45 animals. 

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Did You Know (32)?

Sandwiched between the Pacific and Caribbean, Costa Rica is a hotspot for bird watchers. A total of 894 birds have been recorded in this mountainous country who’s landmass is smaller than West Virginia and just a tad larger than Denmark. With more bird diversity than the United States and Canada combined, over 600 bird species are permanent residents. The diminutive scintillant hummingbird (Selasphorus scintilla), is Costa Rica’s smallest bird species while the 6.5 kg jabiru (Jabiru mycteria) is their largest. Ironically, the country known for flamboyant birds like the resplendent quetzal (Pharomachrus mocinno) and scarlet macaw (Ara macao) has chosen the drab clay-colored robin (Turdis grayi) as its national bird.

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Did You Know (31)?

There can be interesting parallels between one’s belief system and a scientific world view. While one is based on a empirical methodology and the other on story telling, what can seem so different will often collide in interesting ways. Consider the Sumerian texts on human origins. Found on a tablet in the 7000 year old city of Nippur, Mesopotamian, the creation myth claims that the body and blood of a god was mixed with a clay from which humans were made. Here, it is the clay that has an interesting parallel with the origins of life on Earth. 

Abiogenesis is the origin of life from non-life, and requires the *spontaneous assembly of complex organic polymers. Known as macromolecules, these are the proteins that do the work of life, are the nucleic acids that hold the biological code, and the carbohydrates that fuel our existence. Abiogenesis requires that the blocks from which life is built be made in the Earth’s primordial atmosphere, that these blocks spontaneously polymerize, that a membrane concentrate the polymers to facilitate chemistry, and that the first genes, in the form of a molecular code, develop in the absence of a parent gene. Hypotheses and tests support the basis for each of these prerequisites, but it’s a second requirement that collides with the Sumerian myth. The spontaneous assembly of biological polymers from preexisting building blocks involved clay sands. Hot sands surrounding thermal vents could have provided the catalytic energy to assemble molecules without consuming them in a reaction. This hypothesis suggests that a heated clay could have been the substrate necessary to distort life’s building blocks to initiate the dehydration reactions that are now an ubiquitous process for life’s cellular chemistry. While I doubt the ancient Sumerians knew much about dehydration synthesis let alone chemical abiogenesis, I find it interesting that the clay from which humans “formed” was also a key requisite to construct the materials from which we are all assembled.  

*spontaneous: Here the use of spontaneous refers to the assembly or organic molecules in the absence of life. Living organisms are capable of using small building blocks to build large complex molecules like DNA, carbohydrates and proteins.

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