Ecología del guanaco (Lama guanicoe) en la Patagonia chilena: El papel de las interacciones bióticas en su abundancia, distribución y selección de hábitat

• Autores: Esperanza Iranzo Sanz
• Directores de la Tesis: Juan Traba Díaz (dir. tes.), Juan E. Malo Arrázola (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2017
• Idioma: español
• Tribunal Calificador de la Tesis: Jorge Cassinello Roldán (presid.), Javier Seoane Pinilla (secret.), W von Hardenberg (voc.)
• Programa de doctorado: Programa Oficial de Doctorado en Ecología
• Materias:
  • Ciencias de la vida
    • Biología animal (zoología)
      • Ecología animal
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Summary Humans play a key role in the loss of biodiversity that we are facing today. Human activity has a great impact on nature, causing species extinctions and threatening the survival of many species and ecosystems. Large herbivores are not an exception in this framework. Threats to them include poaching, habitat destruction and fragmentation, and the introduction of livestock which competes with wild herbivores and usually forces them to occupy suboptimal habitats. Many conservation actions are carried out to deal with biodiversity loss, outstandingly the declaration of protected areas. When successful, species conservation programs may also lead to the growth and expansion of wild populations outside the protected areas, resulting in conflicts with the socioeconomic development of the neighbouring areas. Torres del Paine National Park (Chile) and its surroundings are a natural area where the socio-economic development and the conservation of wildlife converge. The main economic activity in the area is livestock farming, although in recent years tourism boosted by the National Park has become a complementary source of income. In parallel, the guanaco population growth within the protected area resulting from its protection in the last twenty years has caused its expansion towards surrounding private ranches. There, a conflict between wildlife conservation and economic activity has arisen. In this context, this doctoral thesis takes advantage from the "natural experiment" provided by the protected area and its surroundings that differ basically in the presence of livestock along with wild species. This makes of Torres del Paine a perfect scenario to test diverse ecological hypotheses related with niche theory and the diffusion of populations, as much as to improve the present knowledge of guanaco ecology and behavior, which were the subject of study of this doctoral thesis. The increase in the abundance and occupation area of guanaco could lead to resource competition with livestock outside the National Park. This thesis tryes to (i) determine the existence (or not) of such potential for competition, (ii) study specific aspects of guanaco ecology, (iii) determine the state of its population and (iv) examine interspecific interactions at the community level between native and exotic herbivores. Specifically, this thesis estimates the population size and density of guanacos in the area. It also describes the social and demographic structure of the population and its dispersion pattern, as well as the factors that influence their distribution and social structure (CHAPTER 2). To evaluate the possible consequences of guanacos expanding to private ranches and their potential for competition with livestock, CHAPTER 3 compares habitat selection of both species in sympatry and that of the guanaco in absence of sheep, both in winter and late spring- early summer. Guanacos and sheep are part of a community of wild herbivores in which livestock has recently been introduced, so the processes of niche overlap and segregation due to competition can extend beyond the guanaco-sheep relationship. In order to address the community-level effects of livestock introduction, as well as to detect changes in niche dimensions due to intra- and interspecific competition, CHAPTER 4 analyses niche breadth and niche overlap between all species pairs of the herbivore assemblage. Once the effect of competition in the guanaco niche has been determined, CHAPTER 5 assesses the role of predation risk and habitat structure in the antipredator behaviour of guanaco. Finally, the main findings of this thesis are discussed in CHAPTER 6 and summarized in Conclusions section