Evidence of Spatial Redistribution Without Detectable Genetic Change in the Greater Caribbean Manatee ( Trichechus manatus manatus ) Population of Puerto Rico

ABSTRACT Understanding the genetic diversity and spatial dynamics of small, isolated populations is essential for species conservation. The Greater Caribbean manatee ( Trichechus manatus manatus ) population in Puerto Rico is classified as endangered and has previously shown limited mitochondrial haplotype diversity. In this study, we analysed mitochondrial DNA control region sequences from 36 samples collected between 2010 and 2021 and compared them to 115 previously published sequences. No novel haplotypes were detected; all samples corresponded to the previously reported A01, A02, B01 and B02 haplotypes. Despite this genetic stability, the geographic distribution of maternal lineages showed a possible shift: The B01 haplotype, historically concentrated along the southern coast, was detected in four individuals on the north coast, three of which were neonates. However, the increase in northern B01 frequency was not statistically significant (Fisher's exact test, p = 0.173), likely reflecting the limited sample size. The repeated detection of neonatal B01 individuals nevertheless is consistent with increased use of northern habitats by reproductive females. Given recent evidence of demographic stability with possible moderate population growth in Puerto Rico, these findings suggest localized redistribution within a genetically constrained population. Haplotype and nucleotide diversities remained low (h = 0.514 ± 0.030; π = 0.156% ± 0.001), indicating that ecological changes in habitat use may precede detectable changes in genetic diversity. Continued genetic monitoring integrated with demographic and spatial studies will be necessary to evaluate long‐term connectivity and conservation implications.