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• 1. [Article] Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters

  Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. ...

  Citation × Citation Citation Abstract Copy Title: Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters Author: Strecker, Angela L., Olden, Julian D. Year: 2014 Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. Title: Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters Author: Strecker, Angela L., Olden, Julian D. Year: 2014 Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. Close

• 2. [Article] Increased Habitat Connectivity Homogenizes Freshwater Communities: Historical and Landscape Perspectives

  Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in ...

  Citation × Citation Citation Abstract Copy Title: Increased Habitat Connectivity Homogenizes Freshwater Communities: Historical and Landscape Perspectives Author: Strecker, Angela L., Brittain, Jeffrey Thomas Year: 2017 Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in the largest water development project in the US history, the Columbia Basin Project (CBP; eastern Washington, USA), which also altered environmental conditions; however, the ecological consequences are largely unknown. Using a historical dataset, we examined long-term patterns in zooplankton communities, water chemistry and clarity, testing the hypothesis that increased connectivity will result in taxonomic homogenization. Further, we tested contemporary drivers of communities using a comprehensive set of environmental and landscape variables. Waterbodies were sampled for zooplankton community composition as well as physical and chemical variables inside and outside the CBP using methods consistent with historical studies. We found significant declines in salinity inside the CBP, whereas changes in water clarity were prevalent across all waterbodies. Increased connectivity via canals homogenized zooplankton communities over time, as well as increasing regional richness. Other long-term changes in zooplankton communities may be related to climate change, invasive species, and land-use changes. Synthesis and applications. Though canals may offer species spatial refugia, homogenization may decrease resilience to environmental stressors. These new hybrid aquatic landscapes, or hydroscapes, should be considered carefully in future water development, including specific plans for monitoring of species and environmental conditions, as well as mitigation of undesirable conditions and/or non-native species. Title: Increased Habitat Connectivity Homogenizes Freshwater Communities: Historical and Landscape Perspectives Author: Strecker, Angela L., Brittain, Jeffrey Thomas Year: 2017 Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in the largest water development project in the US history, the Columbia Basin Project (CBP; eastern Washington, USA), which also altered environmental conditions; however, the ecological consequences are largely unknown. Using a historical dataset, we examined long-term patterns in zooplankton communities, water chemistry and clarity, testing the hypothesis that increased connectivity will result in taxonomic homogenization. Further, we tested contemporary drivers of communities using a comprehensive set of environmental and landscape variables. Waterbodies were sampled for zooplankton community composition as well as physical and chemical variables inside and outside the CBP using methods consistent with historical studies. We found significant declines in salinity inside the CBP, whereas changes in water clarity were prevalent across all waterbodies. Increased connectivity via canals homogenized zooplankton communities over time, as well as increasing regional richness. Other long-term changes in zooplankton communities may be related to climate change, invasive species, and land-use changes. Synthesis and applications. Though canals may offer species spatial refugia, homogenization may decrease resilience to environmental stressors. These new hybrid aquatic landscapes, or hydroscapes, should be considered carefully in future water development, including specific plans for monitoring of species and environmental conditions, as well as mitigation of undesirable conditions and/or non-native species. Close