Guanaco colonisation of Tierra del Fuego Island from mainland Patagonia: Walked, swam, or by canoe?

Abstract

Addressed here is the biogeographical-vexing question of why the guanaco (Lama guanicoe) is the only large mammal on the big island of Tierra del Fuego, answered by comparing alternative colonisation hypotheses. A multidisciplinary examination was conducted into the archaeological, ecological, evolutionary, geographical, genomic, glacial and zoological past, plus distribution of native terrestrial vertebrates in the Patagonia of southern South America. Notable disparities exist between main Patagonia (2.5 species/10,000 km 2 ) compared with Tierra del Fuego (1.8). In the similar-sized area of mainland Patagonia just north of the Strait of Magellan there are 12 reptiles, 7 amphibians and 34 mammals = 53 total species; Tierra del Fuego has 13. Despite being the size of Switzerland and only 3.5 km from the mainland, Tierra del Fuego has no species of snakes, salamanders, frogs or turtles, only one lizard, one toad, nine small mammals, one carnivore and one ungulate, the Guanaco.

Historical ecology and current abundance of the translocated Chilla or Grey fox Lycalopex griseus on the large Tierra del Fuego Island shared by Argentina and Chile

“…At the time of Ohlin's visit, Canis (Pseudalopex) lycoides (Philippi, 1896) had just been described with Tierra del Fuego as type locality, and he was likely unaware of the new nomenclature proposed. Because Tierra del Fuego Island and the archipelago where it belongs is considered distinctly separate from Patagonia proper (Franklin, 2022; Oyarzún‐Segovia & Mayorga‐Zúñiga, 2022, and references therein), it is possible that Ohlin was referring to the continental area outside the large island. This may refer to either Chilean Magallanes or Argentinian Patagonia, or both.…”

“…In doing so, they identified several applications of historical ecology to better understand biological invasions and to manage more efficiently the risk that invasive species pose to native ecosystems. Franklin (2022) provides a fascinating example of historical‐environmental analysis of the presence of Guanaco ( Lama guanicoe ) and Culpeo fox ( Lycalopex culpaeus lycoides ) on Tierra del Fuego Archipelago in southernmost South America, stating that: “Ultimately the outcome of this endeavour was based upon a cross‐disciplinary interaction of geography and archaeology with the environmental and biological sciences”. Aware of its shortcomings (Corti & Díaz, 2022), we follow this path, connecting historical accounts of the presence of two foxes on the same archipelago, namely, Culpeo and Chilla fox ( Lycalopex griseus ), starting with Charles Darwin's account (1839).…”

Más hallazgos contra el consenso eco-alarmista

“…De hecho, se ha ido acumulando evidencia de un impacto ampliamente distribuido en los distintos ecosistemas americanos antes de la llegada de los europeos (Mann 2005;Ellis et al 2013), lo que seguramente redundó en extinciones y posiblemente también introducciones locales de especies. Por ejemplo, los registros más recientes del único mamífero de tamaño mediano (10-15 kg) extinto en la porción continental de la Argentina en el Holoceno medio o tardío, el zorro Dusicyon avus, datan de aproximadamente 3000 años antes del C����� �� ���-��������� ₄₈₅ presente (Prevosti et al 2011); y en la isla de Tierra del Fuego es posible que hayan sido los habitantes humanos pre-europeos quienes introdujeron las poblaciones actuales de guanaco hace unos 6700 años (Franklin 2022). La baja riqueza de herbívoros nativos sudamericanos no es consecuencia de la colonización europea, sino de la extinción de megafauna ocurrida a fines del Pleistoceno, luego de la llegada de los humanos originarios, que junto a los cambios climáticos habrían causado estas extinciones (Barnosky and Lindsey 2010;Prates and Pérez 2021).…”