ABC Family and the CW have found their niche in the vast TV landscape by courting teens and young femmes with drama series that turn on tales of first loves, broken hearts, bitchy backstabbers and fabulously dressed vixens.

The boom in young-adult-centric scripted shows on the cabler and the netlet promise to have a strong impact on the creative community in the coming years, as demand for glossy sudsers that speak to young women opens doors at high levels for female writer-producers.

Most significantly, femme scribes are getting opportunities to serve as showrunners and exec producers that would not likely be available on the Big Four and larger cable nets. That means a new generation of women are gaining vital experience that should go a long way, over time, toward swelling the ranks of femmes working at the top of TV’s food chain.

Industry observers compare the current boomlet for femme scribes with the job opportunities that opened for African-American writers and producers a decade ago when the WB Network and UPN both programmed comedy blocks stocked with shows aimed largely at African-American viewers.

Julie Plec, exec producer and co-showrunner of CW’s “The Vampire Diaries,” seized her moment a few years ago when she was working as a producer on the ABC Family dramedy “Kyle XY.” She’d had a range of experience as a producer and exec, but was not a writer per se, and not even a member of the WGA. But when the show got behind on scripts, the exec producers pressed her into service because she had been such a driving force on the show from the start.

“I went from being a non-writing producer to a co-showrunner almost overnight,” Plec says.

“Gossip Girl” exec producer and showrunner Stephanie Savage had a similar experience on Fox’s “The O.C.,” which she helped shepherd during her tenure as McG’s production partner at the Wonderland Sound + Vision banner. After she wrote her first “O.C.” script, it wasn’t long before she was handed exec producer reins on the short-lived WB Network series “The Mountain.” By the time she partnered with “O.C.” creator Josh Schwartz on “Gossip Girl,” there was no question that she would serve as showrunner (especially as Schwartz was birthing NBC’s “Chuck” at the same time).

I. Marlene King, exec producer and co-showrunner of ABC Family’s “Pretty Little Liars,” had zero showrunning experience when she was recruited by ABC Family execs to spearhead the adaptation of the young adult novel series. But she had written a pilot script for the WB Network years before, and ABC Family exec veep Kate Juergens (a WB alum) believed King had the right touch for the show’s blend of murder mystery and teen angst.

“The show came effortlessly to me in terms of my sensibilities,” King says. “It was a perfect match for me and ABC Family, and I don’t think I would have necessarily found that at other networks.”

Rebecca Sinclair, showrunner of CW’s “90210,” took a more traditional path to the top, having logged stints as a staffer on “Freaks and Geeks,” “Buffy the Vampire Slayer” and “Gilmore Girls.” She was focused on fielding her own pilots when the CW came knocking with an offer she couldn’t pass up — to sign up for a few months of running the writers room on “90210” to help get the fledgling series on track. In short order, she took command of the entire vessel.

ABC Family’s “Make It or Break It” is spearheaded by exec producer Holly Sorensen, who had little TV series experience before she launched the drama about teens in the world of competitive gymnastics. And the cabler’s upcoming drama, “Switched at Birth,” is in the hands of tyro showrunner Lizzy Weiss. On the flip side, ABC Family’s first big hit, “The Secret Life of the American Teenager,” stemmed from a project brought to the cabler on spec by Brenda Hampton, the showrunner who made her mark with WB Network’s long-running “7th Heaven.”

To be sure, CW and ABC Family have more incentive to take a shot with less-seasoned scribes because they have a harder time recruiting A-list showrunners, who are accustomed to the bigger budgets and broader audiences found at the Big Four and larger cablers a la USA Network, TNT and FX.

But just as Shawn Ryan went from being a writer on “Nash Bridges” to an influential force when FX gambled on “The Shield,” and just as J.J. Abrams got his start in TV with WB Network’s “Felicity,” CW and ABC Family are helping to groom new heavy hitters. With fewer layers of management, execs have more leeway to go on gut instinct in greenlighting series and producers. Plec and others credit their swift ascent to the support of femme execs like ABC Family’s Juergens and Brooke Bowman.

“I consider myself incredibly lucky that I never had to come up through the ranks as a baby writer,” Plec says. “I was a producer first and then an executive and then able to find my way as a writer. I got to skip a lot of the steps because of the support of people like Brooke and Kate. ”

Plec began her career as an assistant to helmer Wes Craven when he was lensing the first “Scream” feature. She became close friends during that shoot with the movie’s tyro screenwriter, Kevin Williamson, and the two went on to work together on and off for years. When Williamson began working on the “Vampire Diaries” pilot for CW just as “Kyle XY” was ending, it was a natural segue for Plec to reunite with him, this time as a full-fledged showrunner.

Plec, like many of her peers, says her heart is in the genre and teen romance fare that dominates CW and ABC Family.

“I am such a fangirl,” Plec says. “I have never stopped reading young adult novels. I like being able to tell those fun relationship and wish-fulfillment stories. ”

She sees that same passion in younger writers who grew up watching WB shows like Williamson’s “Dawson’s Creek” and Fox’s “Party of Five,” and the expansion of options to work on shows in the same vein is undoubtedly encouraging more young women to aspire to careers in TV.

There is no question that there are increasing numbers of prominent female showrunners on the major nets as well, but research has found that women overall are only inching forward when it comes to achieving the status of series creators and exec producers.

According to the most recent survey from the Center for the Study of Women in Television & Film, run by Dr. Martha Lauzen of San Diego State U., which encompasses primetime broadcast TV series (scripted and reality) in the 2009-10 season, femmes accounted for 21% of series creators, up 3% from the 1997-98 season, and 22% of exec producers, also up 3% from ’97-’98. The WGA West reports similar figures in its periodic breakdown of employment trends for its members. (And as hard as it is for women in TV, the numbers are even worse on the film side.)

“Gossip Girl’s” Savage saw anecdotal evidence of those statistics during the writers strike in late 2007-early 2008, when she attended numerous mass meetings of WGA members.

“I’d look around the room and there were barely any women,” Savage recalls. “If you ever wanted to not have to wait in the line, go to the ladies room at a WGA meeting.”

It’s still particularly an uphill climb for femmes in the writers rooms of primetime comedies, which have been harder to crack than even hardboiled crime and procedural dramas. According to the WGA West’s most recent statistical breakdown of employment among its members, only 25% of the 450 femme scribes employed on primetime series during the 2007-08 season worked on comedy series, a stat that also reflects the tight job market for laffers. (To wit, 39% of the 975 male writers working that season were on comedies.)

Not surprisingly, female employment in TV is strongest at the midlevel rank of producer and supervising producer. Women held 39% of those jobs in the 2009-10 season, up 10% from 97-98, according to Lauzen’s 2010 report titled Boxed In: Employment of Behind-the-Scenes Women in the 2009-10 Primetime Television Season.

As in any industry, one major reason for the disproportionately small number of women running primetime series is the lack of necessary experience for a leadership role. That’s why the growth of opportunities in cable, and for younger women in particular at CW and ABC Family, are seen as so important to grooming the next generation.

Savage has built on her youth-culture cred through the Fake Empire production partnership she launched last year with Schwartz. The company is developing TV shows and digital properties through a deal with Warner Bros. and features films through Paramount. She and Schwartz are focused on working with other writers to shepherd their projects to the screen, as well as developing their own material.

“Pretty Little Liars’ ” King says her success as a first-time showrunner with no prior series staffing experience has only been possible with the help of co-showrunner Oliver Goldstick, a primetime vet, and other senior writers that are mostly men.

“I learn from them every day. When you’re new to it all and you’re thrown in the quicksand, it’s swim or sink,” she says.

“90210’s” Sinclair recently announced her intent to bow out of the show after this season to pursue other passions, like penning a novel. But the experience gained in her time at the helm will enhance her career no matter what she chooses to do next.

“Everything I’ve done for the last two and a half years has been to take a ship that was heading in a direction that I didn’t like and with a determined application of muscle turn it toward something that I could feel proud of,” Sinclair says.