Scientists Find Evidence of Casuarina Hybrids

Sep 14, 2009 By Stephanie Yao
Scientists Find Evidence of Casuarina Hybrids
Australian pine species that have become invasive in southern Florida have been found to hybridize, something that does not appear to happen in their native land. Photo courtesy of Amy Ferriter, State of Idaho, Bugwood.org

(PhysOrg.com) -- Hybrids of the invasive Australian plant species Casuarina exist in Florida, Agricultural Research Service (ARS) scientists and university cooperators have found.

These fast-growing, pine-like trees were historically planted widely as ornamentals and along boulevards in south Florida, and are currently being proposed as a windbreak in citrus groves. However, the trees are frequently the tallest in the canopy and can be very damaging during storms and hurricanes. Casuarina has also become an environmental problem, invading and altering natural habitats including Everglades National Park, home to many threatened and endangered species.

Based on physical characteristics, scientists have long suspected hybridization among the three Casuarina species in Florida—C. glauca, C. cunninghamiana and C. equisetifolia—but it is difficult to verify hybridization by these characteristics alone.

DNA tests conducted by botanist John Gaskin, research leader of the ARS Pest Management Research Unit in Sidney, Mont., confirm the existence of hybrids. Examining the DNA, according to Gaskin, allows for better understanding of the identity of the plants and where they came from, and helps explain how these novel hybrids have become so invasive.

Gaskin collaborated with entomologist Greg Wheeler, with the ARS Invasive Plant Research Laboratory in Ft. Lauderdale, Fla.; Matt Purcell, director of ARS' Australian Biological Control Laboratory in Brisbane; and Gary Taylor, a research associate with the University of Adelaide. The team collected samples from Casuarina species in Australia and Florida. Gaskin then used genetic markers to compare the collections and confirm which species and hybrids currently exist in Florida.

The researchers found that hybrid combinations of C. glauca and C. equisetifolia are present across a wide range of southern Florida. They also found C. glauca and C. cunninghamiana hybridization in one location.

The scientists did not, however, find evidence of hybrids in Australia. This could be problematic for biocontrol efforts, which rely heavily on co-evolution of biocontrol agents and target species to insure the highest rates of effectiveness. Potential biocontrols must now prove effective against parental species and hybrids.

The research was published in the scientific journal Molecular Ecology.

Provided by Agricultural Research Service

Explore further: Seychelles poachers go nutty for erotic shaped seed

add to favorites email to friend print save as pdf

Related Stories

Study: Plants can be divided into species

Mar 22, 2006

Indiana University-Bloomington scientists say the theory that plants cannot be divided into species the same way as animals are identified is wrong.

Researchers shed new light on hybrid animals

Sep 17, 2007

What began more than 50 years ago as a way to improve fishing bait in California has led a University of Tennessee researcher to a significant finding about how animal species interact and that raises important ...

Rubbish heaps helped crops evolve

Aug 20, 2007

Rubbish heaps and backyard gardens helped early farmers domesticate crop plants, according to Oxford University scientists. Their research confirms that seeds and fruits gathered in the wild and then discarded ...

Rust fungus to tear backbone out of boneseed

Jan 29, 2008

CSIRO’s newly refurbished containment facility for exotic insects and plant pathogens in Canberra is hosting a species of rust fungus which shows promise as a biocontrol agent for the highly invasive plant ...

Invasive Species Alter Habitat to Their Benefit

Aug 09, 2006

When scientists study habitats that alien species have invaded, they usually find predictable patterns. The diversity of native species declines, and changes occur in natural processes such as nutrient cycling, wildfire frequency ...

Recommended for you

Seychelles poachers go nutty for erotic shaped seed

8 hours ago

Under cover of darkness in the steamy jungles of the Seychelles thieves creep out to harvest the sizeable and valuable nuts of the famous coco de mer palm, and their activities are threatening its long-term ...

Laser scanning accurately 'weighs' trees

Nov 21, 2014

A terrestrial laser scanning technique that allows the structure of vegetation to be 3D-mapped to the millimetre is more accurate in determining the biomass of trees and carbon stocks in forests than current ...

Cameras detect 'extinct' wallabies near Broome

Nov 21, 2014

Yawuru Country Managers have found a spectacled hare wallaby (Lagorchestes conspicillatus) population, a species which for the last decade was feared to be locally extinct at Roebuck Plains, adjacent to Broome.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.