Friday, August 29, 2014
YOLO COUNTY NEWS
99 CENTS

Hybrid pupfish provide look at natural selection

In lakes on the island of San Salvador, Bahamas, pupfish like this one show rapid evolution to exploit new diets. UC Davis graduate student Chris Martin has bred hundreds of hybrid fish to understand the process. Chris Martin/Courtesy photo

By
From page A1 | January 17, 2013 |

Chris Martin has bred more than 3,000 hybrid fish in his time as a graduate student in evolution and ecology at UC Davis, a pursuit that has helped him create one of the most comprehensive snapshots of natural selection in the wild and demonstrated a key prediction in evolutionary biology.

“We can see a surprisingly complex snapshot of natural selection driving the evolution of new specialized species,” said Martin, who with Professor Peter Wainwright published a paper on the topic in the Jan. 11 issue of the journal Science.

The “adaptive landscape” is very important for evolutionary biology, but rarely measured, Martin said. He’s been fascinated with the concept since high school.

An adaptive landscape takes variable traits in an animal or plant, such as jaw size and shape, spreads them over a surface, and reveals peaks of success (what evolutionary scientists call fitness) where those traits become most effective, or adaptive.

It is a common and powerful idea that influences thinking about evolution. But while the concept is straightforward, it is much harder to map out such a landscape in the wild.

For example, about 50 species of pupfish are found across the Americas. The tiny fish, about an inch or so long, mostly eat algae on rocks and other detritus. Martin has been studying species found only in a few lakes on the island of San Salvador in the Bahamas, where some of the fish have evolved different-shaped jaws that allow them to feed on hard-shelled prey like snails or, in one case, to snatch scales off other fish.

In a paper published in 2011, Martin showed that these San Salvadoran fish are evolving at an explosively faster rate than other pupfish.

Martin brought some of the fish back to the lab at UCD and bred hybrids with fish with different types of jaws. He created about 3,000 hybrids in all, which were measured, photographed and tagged. Martin then took about 2,000 of the fish back to San Salvador.

“It was the craziest thing I’ve done,” Martin said. “I was leaning on the stack of them in the middle of Miami airport.”

Martin released the young fish into enclosures in the lakes of their grandparents. Three months later, he returned to check on the survivors and plotted them out on the adaptive landscape.

Most of the surviving fish were on an isolated peak adapted to a general style of feeding, with another peak representing fish adapted for eating hard-shelled prey. Competition between the fish had eliminated the fish whose jaws put them in the valleys between those peaks. The scale-eating fish did not survive.

The results explain why most pupfish species in America have pretty much the same diets, Martin said. The generalists are essentially stranded on their peak — variants that get too far out fall into the valley and die out before they can make it to another peak.

“It’s stabilizing selection,” he said. An early burst of variation when fish entered a new environment with little competition could have allowed the shell-eaters and scale-eaters to evolve on San Salvador.

The work was supported by grants from the National Science Foundation.

— UCD News Service

Comments

comments

Special to The Enterprise

.

News

Davis Innovation Center team fields questions

By Dave Ryan | From Page: A1 | Gallery

 
Saving Putah Creek: a quiet concert at sunset

By Elizabeth Case | From Page: A1 | Gallery

Mr. Dolcini goes to Washington

By Tanya Perez | From Page: A1 | Gallery

 
Winton to be feted for her many years of community work

By Bruce Gallaudet | From Page: A1 | Gallery

Researchers solve mystery of Death Valley’s moving rocks

By The Associated Press | From Page: A2 | Gallery

 
California extends review of $25B delta plan

By The Associated Press | From Page: A2

 
Assembly approves statewide ban on plastic bags

By The Associated Press | From Page: A2

Forum explores local mental health services

By Enterprise staff | From Page: A3

 
Solar-cooking workshop set at Food Co-op

By Enterprise staff | From Page: A3

Celebrate the Senior Center at Sept. 9 luncheon

By Enterprise staff | From Page: A3

 
Need a new best friend?

By Enterprise staff | From Page: A3 | Gallery

Equestrian eventing competition slated

By Enterprise staff | From Page: A3

 
Dinner, auction benefit Yolo County CASA

By Enterprise staff | From Page: A3

Kids can sign up for a library card and get a free book

By Special to The Enterprise | From Page: A4

 
Explorit Science Center: Volunteers supercharge summer camp

By Lisa Justice | From Page: A4 | Gallery

Tee off for Davis’ continued prosperity

By Lily Holmes | From Page: A4

 
 
Bodega Marine Laboratory hosts open house

By Special to The Enterprise | From Page: A5 | Gallery

Local group charts a year’s worth of beauty in flowers

By Enterprise staff | From Page: A5

 
Free blood pressure screenings offered

By Enterprise staff | From Page: A5

Name Droppers: UCD honors two of its own

By Enterprise staff | From Page: A6

 
Books, conversation and poetry at Logos

By Enterprise staff | From Page: A7

 
.

Forum

Let’s sell the MRAP on eBay

By Letters to the Editor | From Page: C2

 
Seeing both sides of ‘tank’

By Letters to the Editor | From Page: C2

What if we need MRAP?

By Letters to the Editor | From Page: C2

 
How could tank be helpful?

By Letters to the Editor | From Page: C2

 
Tom Meyer cartoon

By Debbie Davis | From Page: C2

Don’t sentence our police to death

By Special to The Enterprise | From Page: C2, 1 Comment

 
Will Davis see river water?

By Letters to the Editor | From Page: C2

Travel buddy is getting too fat

By Creators Syndicate | From Page: B5

 
.

Sports

Forget the score; focus on the energy brought by Aggies

By Bruce Gallaudet | From Page: B1

 
Returning seniors, new faces lead promising DHS links squad

By Evan Ream | From Page: B1 | Gallery

Devil golfers return from Scotland with smiles on their faces

By Evan Ream | From Page: B1 | Gallery

 
Devils scrimmage with Sac

By Wayne Tilcock | From Page: B1 | Gallery

UCD-Stanford: the clock is down to counting the minutes

By Bruce Gallaudet | From Page: B1

 
Sports briefs: DHS girls fall by the slimmest of net margins

By Enterprise staff | From Page: B6 | Gallery

Wire briefs: Aces cruise past Cats at Raley

By Wire and staff reports | From Page: B6

 
.

Features

.

Arts

‘The November Man’: Who can be trusted?

By Derrick Bang | From Page: A9 | Gallery

 
B Street’s ‘The Ladies Foursome’ is aces

By Bev Sykes | From Page: A9 | Gallery

.

Business

Technology makes a great car better

By Ali Arsham | From Page: C1 | Gallery

 
.

Obituaries

Margarita Elizondo

By Special to The Enterprise | From Page: A4

 
Elaine Dracia Greenberg

By Special to The Enterprise | From Page: A4

.

Comics