ResumoGeneral Introduction 1. The problem 2. Thermal variation and thermal physiology: the role of upper thermal limits 3. A special context: predictability matters 4. Underlying mechanisms 5. What about spatial thermal variations? The role of behavior in extreme thermal landscapes Objectives and Approach Main objective Specific objectives Chapter 1. Within the smallest grid: local microclimatic thermal

First at all, I want sincerely to thank my Heavenly Father and Friend for giving me the strength and courage every day, and for bringing me to this point of my career. He is my source of inspiration, who leads my life beyond I can desire, plan and imagine, so all the honor that this dissertation may deserve is primary to Him. Likewise, I am especially grateful with my wife, my parents and my sister for their company, for believing in me and for encouraging me to surpass myself every day. Also my wife's family, who is my second family. I am very privileged for having all them in my life, they are the strongest motivation I have to strive, go on and succeed. That all my achievements be not just source of proud for them, but also contribute to improve their lives. Many thanks to my adviser, Prof. Dr. Carlos Navas, not just for his invaluable guidance through my career, which makes this dissertation possible, but also for his wise advices in many aspects of my life, for trusting me, for guiding me in a new country, for opening the doors of his house and family to his students, for all the funny times with pizza, beer, stories, colombian food, etc. He is not only my adviser or my professor, but my master and friend, and I still have and want to learn so many things of him. Thanks 'profe'. I want to briefly thank the people that in one way or another have contributed to my Master dissertation and to the path I have walked in Brazil to get here. My aunt Luz Encir and the family Villegas Cantero for all their trust and support to me and my wife. The professors Fernando Ribeiro Gomes and Renata Guimarães Moreira Whitton, who have taught me and inspired me a lot, I am very grateful for their support, kindness and advices. My dear friend Carla Madelaire, a woman who I admire a lot, many thanks for her true friendship, for all the laughs and also our discussions about science and life. Thanks to all my partners of the 'LEFE' and the staff of the Department of Physiology for all their support and contributions through this time. Many thanks to all people of the ICT São Paulo for their affection and friendship, especially Miguel Hernández and his family for their guide and company. Finally, I want to acknowledge the institutions that made possible this dissertation.