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At present, approximately 1500 asteroids are known to evolve inside or sticked to the exterior 1:2 resonance with Mars at a 2.418 AU, being (142) Polana the largest member of this group. The effect of the forced secular modes superposed to the resonance gives rise to a complex dynamical evolution. Cha- otic diffusion, collisions, close encounters with massive asteroids and mainly orbital migration due to the Yarkovsky effect generate continuous captures to and losses from the resonance, with a fraction of aster- oids remaining captured over long time scales and generating a concentration in the semimajor axis dis-Keywords: tribution that exceeds by 20% the population of background asteroids. The Yarkovsky effect inducesAsteroids, Dynamics different dynamics according to the asteroid size, producing an excess of small asteroids inside the reso-Asteroid Vesta nance. The evolution in the resonance generates a signature on the orbits, mainly in eccentricity, thatResonances, Orbital depends on the time the asteroid remains captured inside the resonance and on the magnitude of the Yar-Rotational dynamics kovsky effect. The greater the asteroids, the larger the time they remain captured in the resonance, allow- ing greater diffusion in eccentricity and inclination. The resonance generates a discontinuity and mixing in the space of proper elements producing misidentification of dynamical family members, mainly for Vesta and Nysa-Polana families. The half-life of resonant asteroids large enough for not being affected by the Yarkovsky effect is about 1 Gyr. From the point of view of taxonomic classes, the resonant population does not differ from the background population and the excess of small asteroids is confirmed.