Featured Research

from universities, journals, and other organizations

Manatee subspecies genetically confirmed, but diversity challenge looms

Date:
September 13, 2010
Source:
United States Geological Survey
Summary:
The first genetic study to compare nuclear DNA of endangered Antillean manatees in Belize with Florida manatees confirmed their designation as separate subspecies. Belize's manatees, however, were found to have extremely low genetic diversity, raising questions about their long-term genetic viability.

Wild Florida Manatees enjoy warm spring current of Crystal River in Florida during winter.
Credit: iStockphoto/Yuko Hirao

The first genetic study to compare nuclear DNA of endangered Antillean manatees in Belize with Florida manatees confirmed their designation as separate subspecies. Belize's manatees, however, were found to have extremely low genetic diversity, raising questions about their long-term genetic viability.

The Central American country of Belize hosts the largest known breeding population of Antillean manatees and is touted by biologists for its potential to repopulate other parts of Central America where manatees are severely reduced, rare or absent.

"It turns out that the genetic diversity of Belize's manatees is lower than some of the classic examples of critically low diversity" said U.S. Geological Survey (USGS) conservation geneticist Margaret Hunter, Ph.D., who led a molecular DNA study of genetic diversity in the Antillean subspecies in Belize.

Belize's Antillean populations scored lower in genetic diversity than textbook examples of "bottlenecked" endangered species such as Wanglang giant pandas, the East African cheetah and an island koala population founded by only three koalas.

Endangered species need genetic diversity to weather threats to their survival, including random or rare shocks such as disease, hurricanes or habitat destruction. When a population drops to low numbers, the diversity of its gene pool also shrinks. Even after it rebounds to greater numbers, that population decline leaves a legacy of reduced genetic diversity known as a bottleneck. This renders the population more vulnerable to future shocks, explained Hunter.

The low genetic diversity in Antillean manatees is attributed, in part, to centuries of hunting that were only curtailed early in the 20th century. Once found throughout coastal regions of Central and South America, Antillean manatees are now rare or absent in parts of Central America where they used to be considered abundant. Today, even Belize only hosts about 1,000 individuals -- a number well below the threshold recommended for long-term sustainability, said Hunter.

Distinct Populations Offer Opportunity

Although the study found low overall genetic diversity in Belize, notable differences were found in manatees that live near Belize City compared to manatees living in lagoons, rivers, and cayes farther south. These differences, said Hunter, equate to genetic variation, which is valuable for sustaining a diverse gene pool.

"When it comes to the sustainability of a species, this is the type of genetic diversity you want to preserve for the future," explained Hunter.

To sustain the diverse gene pool these populations offer, managers will need to consider methods of enabling natural migration and mixing to take place between the two populations.

"These results show the importance of corridors of suitable habitat and low human impact that allow manatees to travel between key sites," said co-author Nicole Auil Gomez, a Belizean biologist who does consulting for the Florida-based conservation organization Sea 2 Shore Alliance.

"Leaving pockets of habitat is no longer enough," she added.

Confirmation of the Subspecies

The genetic evidence that Florida manatees (Trichechus manatus latirostris) are not regularly mixing with populations of Antillean manatees (Trichechus manatus manatus) in Belize means they don't naturally affect each other's population size or genetic diversity, Hunter said.

The question of whether these two seemingly distant populations were interbreeding had been raised in light of radiotracking evidence that manatees are capable of migrating long distances. Florida manatees have turned up in places as far as Rhode Island, the Bahamas and Cuba.

The only prior genetic data comparing the subspecies came from mitochondrial DNA, which is useful for understanding historical relationships on an evolutionary time scale (think millennia, not decades). By including nuclear DNA, this study provided a modern-day assessment of whether the two populations are migrating and interbreeding.

"We are continuing to piece together the genetic relationships of manatees throughout the Caribbean and it's giving us insights into how to maintain healthy and stable populations," said USGS biologist and co-author Bob Bonde, Ph.D.


Story Source:

The above story is based on materials provided by United States Geological Survey. Note: Materials may be edited for content and length.


Journal Reference:

  1. Hunter et al. Low genetic variation and evidence of limited dispersal in the regionally important Belize manatee Reduced Belize manatee dispersal and genetic variation. Animal Conservation, 2010; DOI: 10.1111/j.1469-1795.2010.00383.x

Cite This Page:

United States Geological Survey. "Manatee subspecies genetically confirmed, but diversity challenge looms." ScienceDaily. ScienceDaily, 13 September 2010. <www.sciencedaily.com/releases/2010/09/100913132337.htm>.
United States Geological Survey. (2010, September 13). Manatee subspecies genetically confirmed, but diversity challenge looms. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2010/09/100913132337.htm
United States Geological Survey. "Manatee subspecies genetically confirmed, but diversity challenge looms." ScienceDaily. www.sciencedaily.com/releases/2010/09/100913132337.htm (accessed April 23, 2014).

Share This



More Plants & Animals News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Leopard Bites Man in India

Raw: Leopard Bites Man in India

AP (Apr. 22, 2014) A leopard caused panic in the city of Chandrapur on Monday when it sprung from the roof of a house and charged at rescue workers. (April 22) Video provided by AP
Powered by NewsLook.com
Iowa College Finds Beauty in Bulldogs

Iowa College Finds Beauty in Bulldogs

AP (Apr. 22, 2014) Drake University hosts 35th annual Beautiful Bulldog Contest. (April 21) Video provided by AP
Powered by NewsLook.com
805-Pound Shark Caught Off The Coast Of Florida

805-Pound Shark Caught Off The Coast Of Florida

Newsy (Apr. 22, 2014) One Florida fisherman caught a 805-pound shark off the coast of Florida earlier this month. Video provided by Newsy
Powered by NewsLook.com
Breakfast Foods Are Getting Pricier

Breakfast Foods Are Getting Pricier

AP (Apr. 21, 2014) Breakfast is now being served with a side of sticker shock. The cost of morning staples like bacon, coffee and orange juice is on the rise because of global supply problems. (April 21) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins