Pre-Holocene Origin for the Coronopus navasii Disjunction: Conservation Implications from Its Long Isolation

Area of Science:

• Botany
• Conservation Biology
• Evolutionary Biology

Background:

• The endangered Coronopus navasii (Brassicaceae) recovery plan was disrupted by new population discoveries 500 km north of its known range.
• Management has been delayed due to limited data on new populations and administrative inertia.

Purpose of the Study:

• To analyze the origin of the disjunction in Coronopus navasii populations using molecular data and species distribution models.
• To provide a scientific basis for reassessing and updating the conservation and recovery plan for Coronopus navasii.

Main Methods:

• DNA sequencing (plastid and ribosomal DNA) was used to analyze genetic relationships and divergence times.
• Species distribution models were employed to infer past distribution and dispersal patterns.
• Haplotype network analysis was conducted to understand gene flow and population structure.

Main Results:

• Molecular data dated the disjunction between Miocene-Pleistocene (6.30-0.49 Mya, plastid DNA) and Pleistocene (1.45-0.03 Mya, ribosomal DNA), ruling out human influence.
• Low gene flow and haplotype network structure suggest long-term isolation and a northward dispersal from Southeast Spain.
• The species' suitable habitat is projected to shift northward under future climate change scenarios.

Conclusions:

• The disjunction of Coronopus navasii is attributed to natural dispersal, not human activity.
• Despite a potentially improved conservation status due to wider distribution, long-term survival is threatened by habitat fragmentation, genetic isolation, and climate change.
• Integrating newly discovered Central-East Spanish populations into the recovery plan is crucial for preserving genetic diversity and ensuring species survival.