Decreased habitat area for most taxa
We projected each clade distribution onto geographic space for present day and LGM climate. Consistent with the niche breadth results, northern clades distributed over wider areas for present day climate than southern clades (Figure 2). Most clades showed a reduction in their distribution area towards the eastern coast of the southern half of the peninsula (BCS) when projecting our models to LGM (Supporting Information). During LGM the peninsula was colder, drier in the south and wetter in the north (Figure 1, Antinao & McDonald, 2013; Antinao et al., 2016), conditions that could have been more challenging for desert-adapted species and therefore constrained their distributions. In general, organisms inhabiting arid sub-tropical regions have been described to show heterogeneous responses to Pleistocene climatic variation compared to organisms from temperate regions, since their response is highly dependent on local precipitation patterns (e.g. Anadón et al., 2015). The population contraction and subsequent isolation during Pleistocene glaciations could have produced and/or strengthened the divergence between genetic groups (Dolby et al., 2015; Araya-Donoso et al., 2022; Dolby et al., 2022).
Previous distribution modeling studies in this area have detected different patterns of LGM distribution. Some studies have detected population expansion towards LGM (Graham et al. 2014; González-Trujillo et al. 2016; Harrington et al. 2017; Arteaga et al. 2020), whereas others have detected range reductions (Valdivia-Carrillo et al. 2017; Klimova et al. 2017). Moreover, Cab-Sulub & Álvarez-Castañeda (2021) detected different patterns depending on the genetic clade within each taxon, in which southern clades showed area reduction and northern clades showed expansion. The differences between those studies and ours could be due to the modeling algorithm since all those studies implemented Maxent and we used minimum volume ellipsoids (See Supporting Information for further discussion).