Freddie Reichel AP Biology

2/28/16 Current Event #13

“In DNA, Clues to the Cheetah’s Speed and Hurdles”

Through a cheetah named Chewbaaka, scientists have uncovered the species’ long complex history, including how the cheetah became the world’s fastest land animal.  Chewbaaka was rescued as a 10-day-old orphan in Namibia and died in 2010 at the age of sixteen, twice the average lifespan of the cheetah in the wild.  However, geneticists were able to draw his blood and six other cheetahs from Namibia and East Africa.  This blood sample has been used to sequence the species’ complete genome; its full set of chromosomes.  The cheetah are characterized by their spotted coats and black “teardrop” facial markings.”  The animals race across the African savanna at speeds reaching 70 miles per hour, due to their unique physiology: elongated legs, aerodynamic skull, enlarged adrenal glands and heart muscles, and claws that grip the earth.  The cheetah is critically endangered, only 10,000 today, the majority living in southern and eastern Africa.  The genomic analysis is not encouraging; the cheetah has less than 5 percent of the genomic diversity of other wild cats, a level significantly lower than even inbred domestic dogs and cats and the lowest among the thirty mammals whose genomes have been sequenced.  Furthermore, genetic diversity is defined by the variation in enzyme genes inherited by an animal’s two parents.  It is vital to the species healthy reproduction and immunity to disease.  This genomic analysis confirmed scientists suspicions that the cheetah is “genetically monotonous.”  Several decades ago, surgical skins grafts were obtained experimentally among unrelated cheetahs and were tolerated without the normal rate of tissue rejection, as if all the animals were identical twins.  Cheetahs in captivity were difficult to breed and had unusually high mortality rates among the cubs, in addition to high vulnerability to the outbreak of disease.  This research was conducted by scientists at the Theodosius Dobzhansky Center for Genome Bioinformatics at St. Petersburg State University in Russia collaborated with BGI-Shenzhen in China and the Cheetah Conservation Fund to analyze the entire genome of the species.  These scientists figured out the specific underpinnings of the cheetah’s genetic impoverishment and the evolutionary sequence of events that created the cheetah’s unparalleled running speed.  The 3,000,000 year old tale of the cheetah is “punctuated” by two significant events that resulted in reduced genetic diversity.  The fossil record shows that about 100,000 years ago, when cheetahs inhabited North America alongside the puma, cheetah migrated across the Bering Strait into Asia, and ultimately into Africa, producing a series of population “bottlenecks.”  As a result, the number of animals dropped so low that the cheetah interbred to survive.  Late in the Pleistocene epoch, a global extinction caused cheetah populations to dwindle, resulting in inbreeding.  The cheetah barely escaped extinction.  The research scientists focused in on the series of mutations of a specific timetable.  The international team of geneticists calculated exactly when these population bottlenecks occurred.  They coincided with the two ancient events and pinpointed the second, Pleistocene bottleneck, 11,084 to 12,589 years ago.  The cheetah’s incredible running ability is due to natural selection.  Eleven different genes showed evidence of mutations over generations that boosted the animal’s muscle contraction, stress response, and regulation of energy-releasing processes.

This article was informative and interesting.  This scientific research is groundbreaking.  Scientists pinpointed the reason for the lack of genetic diversity in the cheetah and why the specific attributes of the cheetah exist.  The cheetah is an endangered species, as illustrated by the fossil records, because of inbreeding, due to the migration across the Bering Strait into Africa.  The cheetah is the fastest running animal on land because of both natural selection and mutation.  Eleven different genes showed evidence of mutations over generations that boosted the animal’s muscle contraction and stress response.  In addition, this research was relevant to what we are learning in class.  By examining fossils from specific periods and eras of the earth, scientists unearthed evidence of mutations and genetic diversity.

The article summarized the research concisely.  I understood all the terminology and found the description of the evolution of the cheetah’s ability to run to be very interesting.  The article could have been improved by utilizing more quotations from the scientists involved in the research.  The article could also be improved by describing prior research and whether it differs from the current discoveries.

Moffet, Barbara S. "In DNA, Clues to the Cheetah’s Speed and Hurdles."The New York Times. The New York Times, 29 Feb. 2016. Web. 01 Mar. 2016. <http://www.nytimes.com/2016/03/01/science/in-dna-clues-to-the-cheetahs-speed-and-hurdles.html?_r=0>.