In addition to variation in speciation rates, the amount of time and area available for speciation to occur can also influence the size of regional species pools, the amount of in-situ speciation, and thus local community diversity. Terrestrial habitats tend to be older, larger and more stable over geologic timescales than freshwater habitats such as lakes and streams (Miller 2021). However, they also tend to be better connected than freshwater habitats, such that new species more quickly expand their ranges beyond their site of origin. Thus, it may be expected that freshwater systems will tend to have smaller regional species pools, but that in situ speciation plays a larger role than in terrestrial communities, in particular for organisms that cannot disperse through air or over land (Gillespie 2004; Miller et al.2018). Indeed, the best-known cases of recent rapid in situ species radiations occur in lake-inhabiting fishes such as cichlids (McGeeet al. 2020), salmoniformes (Hudson et al. 2011) and pupfish (Rabosky 2020; Miller 2021; Richards et al. 2021). These differences between ecosystems in area and time for speciation to occur have important implications for the recovery of diversity and ecological function after human impacts such as habitat and species loss. For example, immigration from the larger and more connected terrestrial matrix may allow terrestrial communities to recover more quickly over shorter timescales via dispersal. Whereas in freshwater communities due to isolation, the much slower process of speciation may be one of the primary ways these systems recover from species loss.