Phylogeography and Sex-Biased Dispersal across Riverine Manatee Populations (Trichechus inunguis and Trichechus manatus) in South America

Abstract

<p>Phylogeographic patterns and sex-biased dispersal were studied in riverine populations of West Indian (Trichechus manatus) and Amazonian manatees (T. inunguis) in South America, using 410bp D-loop (Control Region, Mitochondrial DNA) sequences and 15 nuclear microsatellite loci. This multi-locus approach was key to disentangle complex patterns of gene flow among populations. D-loop analyses revealed population structuring among all Colombian rivers for T. manatus, while microsatellite data suggested no structure. Two main populations of T. inunguis separating the Colombian and Peruvian Amazon were supported by analysis of the D-loop and microsatellite data. Overall, we provide molecular evidence for differences in dispersal patterns between sexes, demonstrating male-biased gene flow dispersal in riverine manatees. These results are in contrast with previously reported levels of population structure shown by microsatellite data in marine manatee populations, revealing low habitat restrictions to gene flow in riverine habitats, and more significant dispersal limitations for males in marine environments.</p>

The Antillean manatee (Trichechus manatus manatus) along the Caribbean coast of Colombia: underused incidental records help identify present and past coastal‐lowland hotspots

“…If, as according to Satizabal et al (2012), genetic exchange between subpopulations is strongly mediated by highly dispersive males, a divergent sex ratio might be expected for the animals in the coastal manatee hotspots. Excluding archaeological and toponym records, in the current sample of 63 manatees tallied from “recent” records, the sex of 19 animals (30%) was identified: 8 females and 11 males (Table 2).…”

“…Manatees show a strong preference for freshwater but also frequent coastal estuarine and marine waters. Satizabal et al (2012) provided evidence that genetic exchange between spatially isolated subpopulations of the West Indian manatee is mediated by highly dispersive males (Castelblanco‐Martínez et al, 2012). Manatees in Colombia benefit from a relatively extensive and detailed protection plan, broadly supported by the public and many universities and nongovernmental parks and conservation organizations (as listed by Caicedo‐Herrera et al, 2004).…”

“…For example, Castelblanco‐Martínez et al (2015) showed that 89% of manatee habitat in the Colombian‐Caribbean basin lies outside of protected areas and they stressed the importance of broader protection. Similarly, Satizabal et al (2012) stressed the urgent need to extend protection from a purely riverine basis to a wider scale to help preserve genetic connectivity in this species. As the only way for manatees of different river systems to connect is via the sea, safe passage through estuarine and coastal marine waters is critical to maintaining their genetic integrity.…”

“…The identification of the potential coastal lowland manatee hotspots alluded to by fishers (Kiszka, 2014) and their effective inclusion into the protected areas network, could provide a much‐needed boost to manatee conservation in Colombia. The findings of Satizabal et al (2012) suggest that coastal manatee hotspot areas may play a pivotal role in maintaining genetic exchange between manatee subpopulations and should therefore be considered as high priority areas for conservation. For cryptic megafauna species (like the manatee) in which detailed and in‐depth studies are difficult or remain lacking, the mapping of occurrences, sightings, and other types of records can be an initial step towards identifying areas of priority or special interest to conservation (e.g., Debrot et al, 2020), similar to other rare and endangered marine species (e.g., Leopold et al, 2019).…”