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).