Mangrove diversity is more than fringe deep

Area of Science:

• Ecology
• Genetics
• Conservation Biology

Background:

• Mangroves are vital coastal ecosystems providing shoreline protection.
• They are generally perceived to have low genetic diversity with structure increasing along coastlines.

Purpose of the Study:

• To investigate the genetic structure of Rhizophora mangle (red mangrove) at fine and broad spatial scales.
• To test the hypothesis that genetic structure primarily increases with distance along a coastline.

Main Methods:

• Conducted genetic analyses on 269 Rhizophora mangle trees across Honduras.
• Utilized 677 single nucleotide polymorphism (SNP) markers developed with 2b-RAD methodology.
• Examined genetic differentiation within a 400 m² parcel and across sites 6-115 km apart.

Main Results:

• Identified two distinct genetic clusters within the 400 m² parcel, showing high differentiation (FST = 0.355).
• Observed limited genetic differentiation (FST = 0.027-0.105) across larger distances (6-115 km).
• Found significant genetic differentiation between seaward fringe and interior forest clusters within the parcel, and between interior clusters and other sites.

Conclusions:

• Genetic structure in mangroves is not solely determined by distance along a coastline.
• Fine-scale genetic structure exists within mangrove forests, particularly between seaward and interior populations.
• These findings have implications for understanding mangrove resilience and conservation strategies.