Water in Los Angeles: A Portrait of an Urban Ecosystem

Orsi, Jared

doi:10.1525/california/9780520238503.003.0001

Cited by 1 publication

(1 citation statement)

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“…Some of the most highly modified habitats in southwestern North America include rivers and streams (Benke, 1990 ; Minckley & Marsh, 2009 ; Pringle et al, 2000 ; Propst et al, 2021 ; Ricciardi & Rasmussen, 1999 ), particularly in the southern California‐northern Baja California coast ecoregion, where lowland reaches of major rivers are now channelized in concrete and flows are regulated via dam releases from artificial lakes and reservoirs (Gumprecht, 1999 ; Orsi, 2004 ). This infrastructure was developed to protect the rapidly growing human population of the mid‐20th century from flood damage and to store and divert water in a landscape that was largely devoid of perennial water (Stephenson & Calcarone, 1999 ; Van Wormer, 1991 ).…”

Section: Introductionmentioning

confidence: 99%

Genetic structure and historic demography of endangered unarmoured threespine stickleback at southern latitudes signals a potential new management approach

et al. 2022

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Habitat loss, flood control infrastructure, and drought have left most of southern California and northern Baja California's native freshwater fish near extinction, including the endangered unarmoured threespine stickleback (Gasterosteus aculeatus williamsoni). This subspecies, an unusual morph lacking the typical lateral bony plates of the G. aculeatus complex, occurs at arid southern latitudes in the eastern Pacific Ocean and survives in only three inland locations. Managers have lacked molecular data to answer basic questions about the ancestry and genetic distinctiveness of unarmoured populations. These data could be used to prioritize conservation efforts.We sampled G. aculeatus from 36 localities and used microsatellites and whole genome data to place unarmoured populations within the broader evolutionary context of G. aculeatus across southern California/northern Baja California. We identified three genetic groups with none consisting solely of unarmoured populations. Unlike G. aculeatus at northern latitudes, where Pleistocene glaciation has produced similar historical demographic profiles across populations, we found markedly different demographics depending on sampling location, with inland unarmoured populations showing steeper population declines and lower heterozygosity compared to low armoured populations in coastal lagoons. One exception involved the only high elevation population in the region, where the demography and alleles of unarmoured fish were similar to low armoured populations near the coast, exposing one of several cases of artificial translocation. Our results suggest that the current "managementby-phenotype" approach, based on lateral plates, is incidentally protecting the most imperilled populations; however, redirecting efforts toward evolutionary units, regardless of phenotype, may more effectively preserve adaptive potential.

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