Translocated Species Exceed Alien Species in Homogenizing Freshwater Fish Assemblages

Area of Science:

• Ecology
• Conservation Biology
• Biodiversity Science

Background:

• Nonnative species introductions accelerate biotic homogenization, threatening global biodiversity.
• Uncertainty exists regarding the distinct impacts of alien versus translocated species on biodiversity dimensions.

Purpose of the Study:

• Compare alien and translocated fish contributions to freshwater assemblage homogenization in Yunnan, China.
• Investigate drivers of homogenization, including anthropogenic disturbance, habitat variability, and native biotic resistance.

Main Methods:

• Quantified cumulative beta-diversity changes across taxonomic, phylogenetic, and functional dimensions over time.
• Assessed the influence of environmental and biotic factors on beta-diversity shifts.

Main Results:

• Alien fishes initially caused differentiation, shifting to homogenization over time (taxonomic, functional).
• Translocated fishes consistently drove homogenization across all dimensions, with 4x greater intensity than alien fishes.
• Homogenization was positively influenced by anthropogenic disturbance, habitat variability, and native biotic resistance.

Conclusions:

• Translocated species exert a more significant homogenization effect on freshwater fish assemblages.
• Conservation strategies must prioritize preventing intra-regional translocations and mitigating anthropogenic impacts to maintain ecological integrity.