  We investigate the macroscopic effects of the ingredients that drive the
origin of species through sympatric speciation. In our model, sympatric
speciation is obtained as we tune up the strength of competition between
individuals with different phenotypes. As a function of this control parameter,
we can characterize, through the behavior of a macroscopic order parameter, a
phase transition from a non-speciation to a speciation state of the system. The
behavior of the first derivative of the order parameter with respect to the
control parameter is consistent with a phase transition and exhibits a sharp
peak at the transition point. For different resources distribution, the
transition point is shifted, an effect similar to pressure in PVT system. The
inverse of the parameter related to sexual selection strength behaves like an
external field in the system and, as thus, is also a control parameter. The
macroscopic effects of the biological parameters used in our model reveal thus
fingerprints typical of thermodynamic quantities in a phase transition of an
equilibrium physical system.
