( e believed that for animals with intern...)IMF Launches World’s First DNA Database for Myeloma Patients

e believed that for animals with internal fertilization -- like the livebearing fish Langerhans studies which don't lay eggs-- selection acting within the female's body that biases fertilization toward males with a particular genital morphology has been largely responsible for the generation of genital diversity. Langerhans's finding, however, contradicts that theory: he has shown that female mosquitofish make their choice before mating, and overwhelmingly that choice is made with size being the prize.

Langerhans and colleagues collected about 350 males of Gambusia affinis in Texas and the same number of Gambusia hubbsi in the Bahamas, taking them from both predator and non-predator environments. He found that mosquitofish in predator-free environments had gonopodia 15 percent larger than those in predator-laden environments. That's a heritable trait over generations made easier by the lack of predators. He also observed that the mosquitofish with larger genitalia had slower burst speeds compared with those of smaller genitalia types.

In the laboratory Langerhans took offspring of Texas mosquitofish from both environments and ran a common-garden experiment ?in which all environmental factors are the same for all individuals ?in laboratory aquaria. He found that gonopodia size was larger in the lab for the offspring of parents collected in predator-free environments ?just as in the field ?proving heritability.

Sex, lies and videotape

He even got female selection on film. He examined the mating preference of about 50 mosquitofish females, where each female was placed in an aquarium having two videos playing side-by-side at one end of the aquarium. One video was of a male mosquitofish with an average gonopodium; the other was of a male with a 15 percent larger one. This forced a female to make a pre-mating sexual selection. After testing each individual and devoting over 1,000 minutes of observation, Langerhans found that it wasn't even
'"/>

Source:

Page: 1 2 3 4
Related biology news :

1. Kinovate Life Sciences Launches Nittophase?High Performance Solid Support For Oligonucleatide Synthesis
2. Affymetrix Launches New Globin-Reduction Kits and Protocol Developed with PreAnalytiX
3. Invitrogen Launches i-Path -- A Unique Systems Biology Platform at BIO 2005
4. Biologist Discovers What May Be World’s ‘Pickiest?Mates
5. Timing is everything: First step in protein building revealed
6. Emory Eye Center Implants Its First Retinal Chips In Patients With Retinitis Pigmentosa
7. First atlas of key brain genes could speed research on cancer, neurological diseases
8. First-ever Compounds To Target Only Metastatic Cells Are Highly Effective Against Breast, Prostate, And Colon Cancers
9. NYCs First Rapid HIV Drug-resistant AIDS Case Prompts Call to Step Up HIV Prevention
10. First real-time view of developing neurons reveals surprises, say Stanford researchers
11. Breast-Cancer Risk Linked to Exposure to Traffic Emissions at Menarche, First Birth