Different patterns of niche marginality during LGM for
highland and lowland species
We incorporated two measures of niche marginality in our analyses to
assess habitat quality within our models, which allowed us to infer
changes in population fitness and putative selection pressure from LGM
to present. We detected higher centroid niche marginality during LGM for
most clades, particularly southern highland clades (Figure 3a).
Moreover, within suitable areas some clades presented a higher
proportion of more marginal conditions during LGM (Figure 4). Both
approaches showed consistent results, however the full distribution of
marginal areas provided a more detailed description of how habitat
quality changed through time. Despite a general reduction in the amount
of habitat for all clades and species during LGM, changes in habitat
quality between LGM and present day differed among desert-adapted
lowland taxa and cold-adapted highland taxa. For lowland desert-adapted
species, available environmental conditions were in general more
challenging during LGM (Figure 3, Figure 4), and in the desert regions
from the southern peninsula habitat quality improved more LGM to present
relative to the north (Figure 3, Figure 4). In contrast, for most
highland species habitat quality seems to have declined since LGM, but
particularly in the Northern part of the Peninsula (Figure 3, Figure 4).
Highland species generally present adaptations to cold environments,
such as sustained activity during suboptimal temperatures in the lizardElgaria multicarinata (Kingsbury, 1994) or the structure of
needles in Pinus species (Jankowski et al. 2019). Highland
species being favored during LGM conditions is consistent with studies
from other regions such as the Afromontane forests range expansions in
the Horn of Africa (Casas-Gallego et al., 2023), or Polyepsiswoodlands on the Andes Mountains (Zutta & Rundel, 2017).