Combining niche shift and population genetic analyses predicts rapid phenotypic evolution during invasion

Area of Science:

• Marine Biology
• Evolutionary Ecology
• Invasive Species Research

Background:

• Microevolution in non-native species rarely expands climatic niches, but this may be underestimated.
• Invasions from restricted native ranges might lead to underestimated phenotypic evolution.
• The red seaweed Gracilaria vermiculophylla has rapidly invaded new regions globally.

Purpose of the Study:

• To explore niche shift analyses in Gracilaria vermiculophylla invasions.
• To determine if non-native populations have expanded their climatic niche.
• To assess phenotypic evolution, specifically heat tolerance, during invasion.

Main Methods:

• Genetically informed climatic niche shift analysis comparing native (Japan) and non-native populations.
• Assaying heat tolerance (40°C) in 935 field-collected and 325 common-garden thalli from 40 locations.
• Evaluating cold and low-salinity stress tolerance.
• Analyzing parallel clines in heat tolerance along latitudinal gradients in native and non-native ranges.

Main Results:

• Non-native Gracilaria vermiculophylla populations occupy warmer, less seasonal habitats than native Japanese populations.
• Non-native populations exhibit significantly greater tolerance to extreme heat (40°C) compared to native source populations.
• Non-native populations also show enhanced tolerance to cold and low-salinity conditions.
• Parallel clines demonstrate local adaptation to warmer temperatures in both native and non-native ranges.

Conclusions:

• Rapid evolution, particularly adaptation to warmer temperatures, plays a crucial role in the invasion success of Gracilaria vermiculophylla.
• Genetically informed niche analyses effectively predict phenotypic shifts during invasions.
• This study contributes to resolving the debate on niche conservatism versus rapid adaptation in invasive species.