JAZZ REVIEW : Turtle Island Expands Its Territory : The string quartet adds fusion to its repertoire of bop, blues, rock and swing in a performance at the Irvine Barclay Theatre.

Since its debut album in 1988, the Turtle Island String Quartet has carved its own niche through arrangements of Dizzy Gillespie and Jimi Hendrix tunes as well as its own bluegrass-meets-Charles Ives originals, rather than through works by Beethoven or Mozart. Thursday at the Irvine Barclay Theatre, the foursome expanded its already wide-angle view to include some new territory.

But don’t think for a moment that that means the group took time out from its program of bop, blues, rock and swing to explore the quartets of Haydn--or even Bartok, who would fit more easily into the group’s decidedly contemporary outlook. The new addition to their repertoire was taken from a jazz-fusion band: the Yellowjackets.

The yet-unrecorded treatment of the Yellowjackets “Rain Dance,” arranged by TISQ violinist Darol Anger, fit neatly into the quartet’s scheme, allowing for plenty of rhythmic shifts, percussive play and solos all around. It meshed nicely with its well-known version of Duke Pearson’s “Jeannine”--arranged by the group’s other violinist, David Balakrishnan--which opened the program before it dissolved into “Rain Dance.”

It might be argued that Turtle Island has looked to this genre before, notably with Pat Metheny’s tribute to the late electric bassist Jaco Pastorius, “Jaco,” which it also performed Thursday. But its arrangement of Metheny’s upbeat tune, still one of its most enjoyable numbers, emphasizes its country feel, and “Jaco” comes off as more Texas two-step than backbeat barn-burner.

“Rain Dance” opens up new rhythmic possibilities for the quartet, allowing cellist Mark Summer to display his entire arsenal of slaps, taps and spanks with the bow.

Otherwise, their performance ran true to form, with airings of Oliver Nelson’s “Stolen Moments,” Chick Corea’s “Senor Mouse” and Robert Johnson’s “Crossroads”--all played with exceptional skill and empathy.

The arrangements, mostly by Angor and Balakrishnan, usually begin with considered introductions that hint at the tune to come, then go on to take plenty of liberties with both melody and tempo. Although the endings sometime arrive unexpectedly, the overall effect is fresh and inventive, rather than some standard rehash of a familiar tune.

The quartet’s originals took it one step further. Summer’s “Gettysburg,” with its chamber-music sensibilities tempered with a touch of country blues, was a respectful journey across the famous Civil War battlefield. Balakrishnan’s “Spider Dreams” blended moments of creepy quietness with more dynamic passages that scurried above Summer’s pizzicato.

In addition to the kinds of material it plays, the other component that separates Turtle Island from both the Kronos Quartet and the jazz-minded Uptown String Quartet is its members’ ability to improvise in a smooth, convincing manner.

Although Angor took the majority of the solos, even the newest addition to the group, violist Jeremy Cohen, showed his skill at working off a tune’s melody. His bowed work on “Angel Eyes” brought a sultry tone to the piece’s otherwise delicate airs.