Background <p>Despite its prominent role in contemporary biology and science, the theory of evolution is still contested by many social groups, showing a deficient understanding of its central postulates and low acceptance rates in many countries. A region traditionally understudied in this respect is Latin America. Within this region, Ecuador stands out as a key territory in the history of evolutionary thought, given the importance of the Galápagos fauna to the eventual realization of the fact of evolution by Charles Darwin. In the present study, we investigate the acceptance of the theory of evolution in a heterogeneous sample of pre-service teacher students (enrolled in formal education programs for teaching certification) from the Sierra region and in-service teachers (participating in professional development) from the Amazonia and Galápagos Islands regions. To gain insights into the potential causes of acceptance of evolutionary theory (MATE instrument), a series of sociodemographic variables, as well as measures of knowledge of evolution (KEE) and religiosity (DUREL) were also taken.</p> Results <p>Our results show low values of acceptance (MATE = 67.5 out of 100), a very low level of knowledge (KEE = 3.1 out of 10), and moderate religiosity (DUREL = 3.2 out of 5). The relationship between variables was complex, but two of them showed a trend: knowledge and religiosity affect positively and negatively, respectively, the acceptance of evolutionary theory, although this influence is only moderate and varies between regions.</p> Conclusions <p>A series of potential explanations for this trend are discussed in light of the religious and educational differences of each region.</p>