The small and watery eyes of Trachemys medemi have observed from the Pacific Ocean perspective the toils of Earth for close to eight million years. As revealed by the nests discovered in the Colombian Provinces of Chocó (municipalities of Acandí, Unguía and Río Sucio) and Antioquia (municipalities of Chigorodó y Turbo), close to the Atrato River.
Although this turtle is no more than 22 cms (8.6 in.) long, evolutionary processes have granted it a colored magic to this member of the chelonian group, also known as the Atrato hicotea. The body has thick yellow stripes which lead to the head and continue in orange, it also has an intense orange-colored undershell.
The discovery of this endemic species was carried out by the Mario Vargas Ramírez, Universidad Nacional de Colombia (UNal) Institute of Genetics´ Biodiversity and Genetics Conservation Research Group Director, and Uwe Fritz, Director of the Senckenberg Research Institute of Dresden (Germany), and other scientists.
At a slow pace, but full of faith, the researchers performed genetic tests on 14 specimens in order to determine the history of this novel turtle. “The molecular analyses indicated this was a new species, contradicting what was thought to be the biogeography of hicotea turtles in South America,” said Professor Vargas.
“The molecular analyses indicated this was a new species, contradicting what was thought to be the biogeography of hicotea turtles in South America,”
Vargas says that all living organisms in the world have coded genetic information embedded in chromosomes and mitochondria, making individuals what they are and also carrying the evolutionary history of a species. There, scientists may have access to parts of the genome, which can provide the evolutionary information which reveals the DNA differences between species.
Therefore it is possible to become cognizant of the family, variety, and origin and inclusively of populational aspects such as if a species has been reduced as a consequence of biogeographic events which impacted its evolution.
“In order to observe evolutionary relationships we analyzed mitochondrial and nuclear genes dismissing any relationship with Trachemys venusta callirostris, which inhabits the northern area of Colombia, but we also discovered that Trachemys medemi is a sister species of Trachemys dorbigni, a species of the Río de la Plata and southern Brazil,” said Vargas.
In sight of this new discovery, they questioned: how can a species discovered in the lower Atrato region is akin to another species which thrives approximately 4,500 km (2,796 miles) away? Professor Fritz, who has researched turtles for 30 years, says that the evolutionary history of the Trachemys family is divided into two periods, one which was originated in North America and later migrated towards the south through Mesoamerica and the Caribbean islands.
“The first wave of the ‘conquest’ was held approximately seven to eight million years ago, resulting in Trachemys medemi and T. dorbigni. The most recent wave occurred two to three million years ago which resulted in the species which now inhabits Magdalena and Sinú, Trachemys venusta callirostris, and the Venezuelan subspecies, Trachemys venusta chichiriviche,” said Fritz.
In order to untangle the evolutionary string, scientists used the “molecular clock” technique which helps to surmise when the species separated. The technique links DNA with geological and paleontological information and helps correlate how strong geological events on Earth impacted species origins. By using the technique researchers verified the great biotic exchange in America. Its migratory process towards the south was allowed given the formation of what today is Panama. Great mammals and other groups including turtles passed through this stretch of land, all of which recent research estimate happened since the Miocene period, that is 17 million years ago.
In 1956, researcher Federico Medem –considered the pioneer in turtle and crocodile research in Colombia and South America– was one of the first scientists to sight the species. In fact, in 1958, 1962 and 1975 he referred to turtles thriving in the lower Atrato region which was different from the hicotea which inhabited the Sinú and Magdalena basins.
Vargas claims that for many years they thought that Trachemys medemi was a variant of Trachemys venusta, which came from Mesoamerica, but what really happened is that it never correctly interpreted the features describe by the German researcher.
Several years later, and after intense discussions on turtle evolution, researchers realized that the species Medem referred to was peculiar to Colombian territory and besides that, it had not been yet classified. At this moment in time, they began an adventure which led to this discovery, so that is why they decided to name it medemi.
Just this past October, the species was presented to science. Colombia only had three endemic species: the Magdalena turtle, Podocnemis lewyana, the Atlantic coast turtle, Mesoclemmys dahli, and the Chocó turtle, Kinosternon dunni or Dunn´s Mud turtle.
The discovery of the fourth endemic turtle in Colombia, Trachemys medemi, is now the responsibility of all Colombian nationals. Researchers Vargas and Fritz point out that although the specimens that live within the Katíos Natural Park and the Río Leon Protected Forest Natural Reserve are protected, the situation is not the same in other parts of the country.
Some of the main threats is wildlife illegal trade, as many specimens are captured each year for human consumption during Holy Week as well as broadening of the agricultural frontier, which burns forests and new pastures are grown for cattle.
Researchers suggest including this turtle on the “vulnerable” category of the IUCN Red List of Threatened Species until the conservation status of this hicotea has been thoroughly analyzed. Then, maybe the government and the Conservation institutions will undertake actions to protect it as one of the ancient “conquerors” of Colombian lands.
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