AIC score differences for the three tested X shape models (par, wedge, and const). The AIC score differences are computed by using the model with the second lowest AIC score as reference. The reference model is indicated with the hatched box centred on zero. Model scores are highlighted with a black edge if a significant model preference of that model is detected. Here, we choose a threshold |Δ_AIC|> 4 (marked as black dashed line) as indication of a model preference (Burnham & Anderson 2002).