These models both contrast with variable-speed evolution ("variable speedism"), which maintains that different species evolve at different rates, and that there is no reason to stress one rate of change over another.
Estes modelos contrastan ambos coa evolución a ritmo variable ("variable speedism" na literatura inglesa), que mantén que diferentes especies evolucionan a distintas velocidades, e que non hai ningunha razón para acentuar unha velocidade de cambio sobre outra.