3.3 | Long-term demographic history
Simulations with PSMC indicate that, since the Middle Pleistocene (ca.
500,000 ybp), S. catenatus has had a consistently smallerN e than S. tergeminus (Figure 5). These
results show that S. tergeminus reached a maximumN e of ∼180,000 individuals ca. 400,000 ybp, and
had a stable N e of ~60,000
individuals ca. 40,000−110,000 ybp, during the Upper Pleistocene (Figure
5). After this time, S. tergeminus experienced declines inN e, reaching a size of ~10,000
individuals ca. 10,000 ybp, in the Holocene (Figure 5).
In contrast, S. catenatus reached a larger maximumN e of ∼230,000 individuals ca. 1,000,000 ybp,
during the Lower Pleistocene (Figure 5). This species then experienced
consistent declines in N e until reaching a size
of ~20,000 individuals ca. 25,000−110,000 ybp, during
the Upper Pleistocene (Figure 5). Similar to S. tergeminus , our
demographic simulations suggest that S. catenatus had anNe of < 10,000 individuals ca. 10,000
ybp (Figure 5).