HYDRA for (HYbrid Distance Recombination Algorithm) is a phylogenetic reconstruction software based on the maximum parsimony criterion under Fitch's parsimony. The core of Hydra relies on a memetic algorithm, i.e. a combination of a Genetic Algorithm (GA) and a Local Search (LS) algorithm.

The main features of Hydra are the introduction of a specific crossover operator for trees called DiBIP (Goeffon et al, 2006) used with the GA and the definition of a new neighborhood called progressive neighborhood (Goeffon et al, 2007) used for LS. They both rely on the notion of topological distance.

HYDRA is provided with a set of benchmarks from C. C. Ribeiro. The current version 1.1 is more efficient than version 1.0 when compiled on an Intel or AMD processor implementing SSE2 instructions.

Hydra is freely available for non commercial purpose.

• Linux / Unix : hydra_v12.tgz
• Windows : hydra.exe (optimized version), hydra_nosse.exe (non optimized version)