$J$-holomorphic curves in almost complex surfaces do not always minimize the genus

The adjunction formula computes the genus of an almost complex curve $F$ embedded in an almost complex surface $M$ in terms of the homology class of $F$. If $M$ is Kähler (or at least symplectic) and the self-intersection of $F$ is non-negative then the genus of any other surface embedded in $M$ and homologous to $F$ is not less then the genus of $F$ (the proof of this statement (which is a generalization of the Thom conjecture for $\Bbb C P^2$) was recently given by the Seiberg-Witten theory). This paper shows that the extra assumptions on $M$ are essential for the genus-minimizing properties of embedded almost complex curves.