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Bonde, Robert K.; McGuire, Peter M.; Hunter, Margaret E.
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2012 |
A review of the key genetic tools to assist imperiled species conservation: analyzing West Indian manatee populations.
Jour. Marine Animals & Their Ecology
5(1): 8-19. 2 figs.
–ABSTRACT: Managers faced with decisions on threatened and endangered wildlife populations often are lacking detailed information about the species of concern. Integration of genetic applications will provide management teams with a better ability to assess and monitor recovery efforts on imperiled species. The field of molecular biology continues to progress rapidly and many tools are currently available. Presently, little guidance is available to assist researchers and managers with the appropriate selection of genetic tools to study the status of wild manatee populations. We discuss several genetic tools currently employed in the application of conservation genetics, and address the utility of using these tools to determine population status to aid in conservation efforts. As an example, special emphasis is focused on the endangered West Indian manatee (Order Sirenia). All four extant species of sirenians are imperiled throughout their range, predominately due to anthropogenic sources; therefore, the need for genetic information on their population status is direly needed.
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Hunter, Margaret E.; Mignucci-Giannoni, Antonio A.; Pause Tucker, Kimberly C.; King, Timothy L.; Bonde, Robert K.; Gray, Brian A.; McGuire, Peter M.
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2012 |
Puerto Rico and Florida manatees represent genetically distinct groups.
Conserv. Genet.
13(6): 1623-1635. 3 tabs. 4 figs. + online supplemental material. DOI 10.1007/s10592-012-0414-2 Dec. 2012 (publ. online Oct. 7, 2012).
–ABSTRACT: The West Indian manatee (Trichechus manatus) populations in Florida (T. m. latirostris) and Puerto Rico (T. m. manatus) are considered distinct subspecies and are listed together as endangered under the United States Endangered Species Act. Sustained management and conservation efforts for the Florida subspecies have led to the suggested reclassification of the species to a threatened or delisted status. However, the two populations are geographically distant, morphologically distinct, and habitat degradation and boat strikes continue to threaten the Puerto Rico population. Here, 15 microsatellite markers and mitochondrial control region sequences were used to determine the relatedness of the two populations and investigate the genetic diversity and phylogeographic organization of the Puerto Rico population. Highly divergent allele frequencies were identified between Florida and Puerto Rico using microsatellite (F ST = 0.16; R ST = 0.12 (P < 0.001)) and mitochondrial (F ST = 0.66; Ф ST = 0.50 (P < 0.001)) DNA. Microsatellite Bayesian cluster analyses detected two populations (K = 2) and no admixture or recent migrants between Florida (q = 0.99) and Puerto Rico (q = 0.98). The microsatellite genetic diversity values in Puerto Rico (HE = 0.45; NA = 3.9), were similar, but lower than those previously identified in Florida (HE = 0.48, NA = 4.8). Within Puerto Rico, the mitochondrial genetic diversity values (π = 0.001; h = 0.49) were slightly lower than those previously reported (π = 0.002; h = 0.54) and strong phylogeographic structure was identified (F ST global = 0.82; Ф ST global = 0.78 (P < 0.001)). The genetic division with Florida, low diversity, small population size (N = 250), and distinct threats and habitat emphasize the need for separate protections in Puerto Rico. Conservation efforts including threat mitigation, migration corridors, and protection of subpopulations could lead to improved genetic variation in the endangered Puerto Rico manatee population.
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Luna, Fábia de Oliveira; Bonde, Robert K.; Attademo, Fernanda L. N.; Saunders, Jonathan W.; Meigs-Friend, Gaia; Passavante, José Zanon O.; Hunter, Margaret E.
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2012 |
Phylogeographic implications for release of critically endangered manatee calves rescued in northeast Brazil.
Aquatic Conserv.: Mar. Freshw. Ecosyst.
22(5): 665–672. 2 tabs. 1 fig. DOI: 10.1002/aqc.2260 Publ. online July 4, 2012 in wileyonlinelibrary.com.
–ABSTRACT: 1. The Antillean manatee (Trichechus manatus manatus), a subspecies of the West Indian manatee, is a large-bodied marine mammal found in fresh, brackish, and marine habitats throughout the Caribbean Islands and Central and South America. Antillean manatees in Brazil are classified as critically endangered, with a census size of approximately 500 individuals. The population in the Northeast region of Brazil is suspected to have approximately 300 manatees and is threatened by habitat alteration and incidental entanglement in fishing gear.
2. A high incidence of dependent calf strandings have been identified near areas of altered critical manatee habitat. The majority of the calves are neonates, discovered alive, with no potential mothers nearby. These calves typically require human intervention to survive.
3. Since 1989 the calves have been rescued (N=67), rehabilitated, and released (N=25) to supplement the small wild manatee population. The rescued calves, and those born in captivity, are typically, not released to their rescue location, mainly for logistical reasons. Therefore, phylogeographic analyses can help to identify related populations and appropriate release sites.
4. Here, mitochondrial DNA analyses identified low haplotype (h=0.08) and nucleotide (p=0.0026) genetic diversity in three closely related haplotypes. All three haplotypes (M01, M03, and a previously unidentified haplotype, M04) were found in the northern portion of the region, while only a single haplotype (M01) was represented in the south. This suggests the presence of two genetic groups with a central mixing zone. Release of rehabilitated calves to unrelated populations may result in genetic swamping of locally adapted alleles or genotypes, limiting the evolutionary potential of the population.
5. The small population size coupled with low genetic diversity indicates that the Northeast Brazil manatee population is susceptible to inbreeding depression and possible local extinction. Further conservation measures incorporating genetic information could be beneficial to the critically endangered Brazilian manatee population.
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Pause Tucker, Kimberly C.; Hunter, Margaret E.; Bonde, Robert K.; Austin, James D.; Clark, Ann Marie; Beck, Cathy A.; McGuire, Peter M.; Oli, Madan K.
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2012 |
Low genetic diversity and minimal population substructure in the endangered Florida manatee: implications for conservation.
Jour. Mammalogy
93(6): 1504-1511. 3 tabs. 1 fig. + online supporting information. DOI: 10.1644/12-MAMM-A-048.1 Dec. 17, 2012.
–ABSTRACT: Species of management concern that have been affected by human activities typically are characterized by low genetic diversity, which can adversely affect their ability to adapt to environmental changes. We used 18 microsatellite markers to genotype 362 Florida manatees (Trichechus manatus latirostris), and investigated genetic diversity, population structure, and estimated genetically effective population size (Ne). The observed and expected heterozygosity and average number of alleles were 0.455 ± 0.04, 0.479 ± 0.04, and 4.77 ± 0.51, respectively. All measures of Florida manatee genetic diversity were less than averages reported for placental mammals, including fragmented or nonideal populations. Overall estimates of differentiation were low, though significantly greater than zero, and analysis of molecular variance revealed that over 95% of the total variance was among individuals within predefined management units or among individuals along the coastal subpopulations, with only minor portions of variance explained by between group variance. Although genetic issues, as inferred by neutral genetic markers, appear not to be critical at present, the Florida manatee continues to face demographic challenges due to anthropogenic activities and stochastic factors such as red tides, oil spills, and disease outbreaks; these can further reduce genetic diversity of the manatee population.
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Bibliography and Index of the Sirenia and Desmostylia 