Niche conservatism and spread explain introgression between native and invasive fish

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Genetics

Background:

• Hybridization can drive evolutionary change but poses risks to native biodiversity when invasive species are involved.
• Understanding ecological factors influencing hybridization patterns and the distribution of hybrid individuals is crucial for conservation.
• Invasive species success is often linked to niche conservatism and biotic resistance theories.

Purpose of the Study:

• To investigate ecological factors promoting hybridization between native and invasive fish species.
• To test theories of niche conservatism and biotic resistance in the context of invasion and introgression.
• To assess the role of habitat suitability and invasion source on the success of invasive Eastern Banded Killifish (Fundulus diaphanus diaphanus) and its admixture with native Western Banded Killifish (Fundulus diaphanus menona).

Main Methods:

• Ecological Niche Modeling (ENM) using Maxent to predict habitat suitability for both species based on native ranges.
• Restriction site-associated DNA sequencing to assess admixture levels in individual Banded Killifish.
• Relating ENM predictions and invasion source proximity to admixture indices.

Main Results:

• Invasive Eastern Banded Killifish predominated in areas predicted as suitable by their ENM, supporting niche conservatism.
• Admixture levels increased as the habitat suitability for invasive Eastern Banded Killifish decreased and with increasing distance from the invasion source.
• Habitat suitability for native Western Banded Killifish showed little evidence of providing biotic resistance against invasion or admixture.

Conclusions:

• Ecological niche models can inform conservation strategies for native and invasive taxa.
• Protecting isolated native Western Banded Killifish populations from invasive conspecifics is essential.
• Invasive species success is influenced by habitat suitability and spatial dynamics, rather than solely by native species' resistance.