Perhaps the primary way human impacts can hinder or decrease speciation rates is through the destruction and fragmentation of habitat within which new species are formed (Figure 2, Rosenzweig 2001; Barnoskyet al. 2011). This occurs primarily through deforestation (or any land-use conversion or intensification) on land, and damming, draining and eutrophication in freshwater systems (Butchart et al. 2010; Horváth et al. 2019; Ruckelshaus et al. 2020). Due to the relatively small existing area of freshwater habitats compared to terrestrial regions, future speciation in freshwaters may be more impacted by habitat loss as the small areas available for speciation to occur become smaller still. For example, pollution in freshwater systems can cause eutrophication and hypoxic conditions, which greatly reduce the available amount and diversity of habitats, and often create conditions where endemic species lose all habitat at once (Vonlanthenet al. 2012; Frei et al. 2022). Over time, pollution in freshwater systems can reduce and homogenize ecological niche space previously partitioned by species, especially those formed via adaptive radiation, and lead to the sudden meltdown of species richness in a group, such as in whitefish (Vonlanthen et al. 2012). Overall, human impacts on local diversity may be greater in freshwater ecosystems, both in the short term due to habitat loss, over medium timescales as the recovery of diversity via immigration is limited by dispersal barriers, and over longer timescales as the opportunity for speciation becomes diminished due to anthropogenic activities. Thus, by incorporating speciation into our approach, we can make inference about future changes in richness and turnover in these systems (see Figure 1).