# Impact of insular landscape features on the population genetics of a threatened climbing palm, Korthalsia rogersii Becc., endemic to the Andaman Islands

## TL;DR

This study examines how the landscape of the Andaman Islands affects the genetic diversity of a threatened climbing palm, Korthalsia rogersii, to guide its conservation.

## Contribution

The study provides new insights into the genetic structure and conservation needs of an endemic Andaman Islands palm influenced by island landscapes.

## Key findings

- Moderate to high genetic differentiation was observed between populations, with geographical isolation contributing to divergence.
- The South Andaman population (Chidiya Tapu) has the highest number of private alleles, suggesting it is a genetic diversity reservoir.
- The Bakultala population shows signs of genetic isolation and demographic decline due to high relatedness and reduced allelic diversity.

## Abstract

Despite the critical structural and functional roles of palms in tropical forest ecosystems and their importance in the local economy and livelihood, palms face significant threats from habitat loss and economic exploitation. Many endemic palms on tropical islands warrant conservation strategies aimed at augmenting the existing gene pool to support effective management and long-term protection of genetic diversity. This study investigated the genetic diversity and structure of Korthalsia rogersii, a threatened climbing palm (rattan) endemic to the Andaman Islands in the Bay of Bengal, across seven known populations (including recently identified ones) using microsatellite markers. The aim was to formulate informed conservation strategies by understanding how the island landscape influences the population genetic divergence of the species. Although heterozygosity and bottleneck analyses did not reveal significant genetic diversity loss, a positive correlation between population size and the number of observed alleles points to a potential ongoing decline. Moderate to high genetic differentiation was observed between populations, with geographical isolation contributing to divergence, particularly in the Interview island population. Notably, the South Andaman population (Chidiya Tapu) harbours the highest number of private alleles, despite exhibiting low overall genetic divergence, indicating it may serve as a reservoir of lost genetic diversity. Further, the Bakultala population shows significant within-population relatedness and reduced allelic diversity, indicative of genetic isolation and demographic decline. These findings provide preliminary insights into the role of the island landscapes in the Andaman archipelago in shaping population genetic divergence among plant taxa. Effective conservation strategies should target gene diversity, genetic structure and hotspots of unique alleles identified in the study, prioritising both population size enhancement and genetic augmentation to ensure the long-term survival of K. rogersii.