Cryptic biodiversity and phylogeographical patterns in a snapping shrimp species complex

Area of Science:

• Marine Biology
• Evolutionary Genetics
• Speciation

Background:

• Cryptic species complexes are a significant, yet often overlooked, source of marine biodiversity.
• Understanding the evolutionary processes driving marine fauna speciation is crucial for biodiversity assessments.
• The snapping shrimp genera Alpheus and Synalpheus are known to contain numerous cryptic species.

Purpose of the Study:

• To genetically characterize the Alpheus armillatus species complex across the northern Caribbean, West Atlantic, and Gulf of Mexico.
• To identify distinct lineages and assess reproductive isolation within the Alpheus armillatus complex.
• To investigate the impact of the Isthmus of Panama closure on the genetic structure of these marine populations.

Main Methods:

• Mitochondrial and nuclear DNA sequencing was employed to analyze genetic structure.
• Phylogenetic analyses were conducted to delineate lineages within the species complex.
• Population genetic metrics were used to assess differentiation and demographic history.

Main Results:

• At least three reproductively isolated lineages, likely distinct species, were identified within the Alpheus armillatus complex.
• All major lineages diverged after the closure of the Isthmus of Panama.
• The Gulf of Mexico harbored only one lineage, while other regions showed mixed lineage presence.
• Strong population genetic differentiation was observed between geographical regions within lineages.
• Evidence of demographic expansion and population bottlenecks/recent founding events was found.

Conclusions:

• Evolutionary processes leading to divergence and speciation are common and recent in snapping shrimp.
• The closure of the Isthmus of Panama played a significant role in the diversification of this species complex.
• Limited connectivity among snapping shrimp populations may be a key factor influencing their genetic structure and speciation.