Navigation Links
Fitness in a changing world
Date:10/10/2008

The stickleback fish, Gasterosteus aculeatus, is one of the most thoroughly studied organisms in the wild, and has been a particularly useful model for understanding variation in physiology, behavior, life history and morphology caused by different ecological situations in the wild.

On biological levels from molecular and genetic to developmental and morphological, and finally ending with the population level, it has proven far more complex than even imagined.

Studies of stickleback have provided us with a much better understanding of how organisms cope with new environmental conditions, first through acclimation over an individual's lifespan, and subsequently through adaptation of population via changes in gene form (allele) frequencies.

Given the rapidly changing global environment, this research not only provides insight into evolutionary processes, but is of practical importance in understanding how organisms will adapt to a changing world.

There are two forms of the stickleback: the oceanic and the freshwater type. The oceanic form lives in the ocean and comes into shallow estuarine or freshwater rivers and streams to breed, and has repeatedly given rise to a freshwater form that lives its entire life isolated in freshwater habitats.

Oceanic stickleback are protected by a complete set of bony lateral plates along the sides and dorsal and pelvic spines on the top and bottom of the fish. These structures help the fish survive attacks by birds and other fish-eating predators. The lateral plates develop first at the front of the fish, near the spines, and then are gradually added towards the tail until the entire side of the stickleback is covered.

Freshwater stickleback almost always evolve the loss of lateral plates, and sometimes the spines, as shown in the figure. This evolutionary change can occur very rapidly, sometimes in only dozens of years. An explanation for the loss of the bony plates is that energy is shunted away from bone formation and toward growth and reproduction instead, especially since the freshwater environment is stressful to the fish. In contrast to the ocean, freshwater lakes (especially in the far north) become iced over, limiting the prey items available to stickleback throughout most of the winter.

Coding for the lateral plates was initially determined to have a relatively simple genetic basis with one gene identified as a major contributor, Ectodysplasin-A (Eda). However subsequent mapping showed that in addition to the region of the genome surrounding Eda, two additional blocks of the same chromosome were also tightly linked to each other and the lateral plate trait. Genetic mapping work on Alaskan stickleback was conducted by William Cresko at the University of Oregon and supported by the National Science Foundation.

Fish develop full lateral plates if they have at least one copy of the Eda complete version of the gene (heterozygous or homozygous for the Eda complete allele). The fish lack the full complement of plates if they are homozygous for the recessive gene--Eda low. From the laboratory mapping results, and the rapid loss of plates observed in nature, biologists hypothesized that selection would always be for the Eda low allele in freshwater.

An experimental test by Barrett et al. has shown surprisingly unexpected results in fitness of the fish. The fish's lifespan is approximately a year. Over the course of a year, researchers sampled a controlled population of stickleback. They found that early in life, fish with Eda low were not as successful.

However, midway through their life, the tables turned and the fish with a copy of Eda low were more successful at surviving. In retrospect, these data might not be so surprising given the results from Cresko on the additional linkage blocks. Selection is likely directly on the Eda alleles when the fish is older, but may be on the other linked genomic blocks when the fish is younger, leading to a correlated change in Eda alleles. A challenge now is to determine what these other genes are, and how they might affect traits and fitness.


'/>"/>

Contact: Lily Whiteman
lwhitema@nsf.gov
703-292-8310
National Science Foundation
Source:Eurekalert  

Related biology news :

1. Severely restricted diet linked to physical fitness into old age
2. Built-in exercise monitor predicts fitness
3. Weight Watchers vs. fitness centers
4. Changing the global dietary environment
5. Global deal fuels QUTs world-changing research
6. Changing environment organizes genetic structure
7. Agriculture is changing the chemistry of the Mississippi River
8. Climate changing gas from some surprising microbial liaisons
9. Warming climate is changing life on global scale, says new study
10. The drivers of tropical deforestation are changing, say scientists
11. Himalaya -- Changing Landscapes photo exhibition draws attention to the impacts of climate change
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Fitness in a changing world
(Date:1/25/2016)... Pa. , Jan. 25, 2016   Unisys Corporation ... system at John F. Kennedy (JFK) International Airport, New ... Protection (CBP) identify imposters attempting to enter the ... not belong to them. pilot testing of the ... initially at three terminals at JFK during January 2016. --> ...
(Date:1/21/2016)... PUNE, India , January 21, 2016 /PRNewswire/ ... According to a new market research report "Emotion ... Learning, and Others), Software Tools (Facial Expression, Voice ... and Regions - Global forecast to 2020", published ... Market is expected to reach USD 22.65 Billion ...
(Date:1/18/2016)... , Jan. 18, 2016  Extenua Inc., a ... simplifies the use and access of ubiquitous on-premise ... partnership with American Cyber.  ... experience leading transformational C4ISR and Cyber initiatives in ... the latest proven technology solutions," said Steve ...
Breaking Biology News(10 mins):
(Date:2/4/2016)... ... February 04, 2016 , ... Shimadzu ... quad LC-MS, host live demos and poster sessions, and present on the analysis ... conference takes place March 6 to 10 at the Georgia World Congress Center ...
(Date:2/4/2016)... MONMOUTH JUNCTION, N.J. , Feb. 4, 2016 ... critical care immunotherapy leader commercializing its flagship CytoSorb® ... and cardiac surgery patients around the world, announced ... PhD, will present at the Source Capital Group,s ... overview and update on the company.  ...
(Date:2/4/2016)... ContraVir Pharmaceuticals, Inc. (NASDAQ: CTRV ), ... of targeted antiviral therapies, announced today that it will ... be held February 8-9, 2016, at the Waldorf Astoria ... & Healthcare Conference, taking place in New ... James Sapirstein , Chief Executive Officer of ContraVir, will ...
(Date:2/4/2016)... Oakland, California (PRWEB) , ... February 04, 2016 ... ... Artificial Intelligence (AI) and leading supplier of Semantic Graph Database technology has been ... Graph Database Products ” by Corporate America Magazine. , “At Corporate America, it’s ...
Breaking Biology Technology: