The acceptance of evolution by Greek students aged 17 has never been actually measured neither via a poll survey nor with the application of any of the existing psychometric tools that have been developed for this purpose. In this research, GAENE 2.1 was chosen because it is a one-dimensional tool that can only measure the acceptance of evolution and does not contain items related to the understanding of evolution and the respondent’s religious beliefs. The assessment of the appropriateness of the tool for our sample was tested with the criteria of Rasch model. Despite the fact that some of GAENE 2.1 items may not show the expected statistical fit and probably overestimates the levels of acceptance of evolution, the tool is appropriated to measure with efficiently and effectively way the acceptance of evolution in the specific sample.

An issue that might concern the species problem is the understanding and acceptance of evolution by students. The reason is that some of the modern concepts, which have been developed to define the species category, do not fit the evolutionary theory. In addition, some other concepts are simply criteria for the delimitation of species taxa. In particular, the biological and morphological species concepts, which are present in every textbook and are used almost exclusively in the teaching of evolution, can intensify students’ essentialist perceptions. However, these perceptions could be effectively dealt with the development of the species problem and the nature of species taxa in the classroom, and also the treatment of species as one more level of organization of biological systems during teaching process. This approach is employed in a lesson with a view to contributing to the structure of a fully developed conceptual framework by the students in order to understand the evolution.