Featured Research

from universities, journals, and other organizations

Sperm wars ruled by females? Females play active, pivotal role in postcopulatory processes

Date:
June 10, 2013
Source:
Syracuse University
Summary:
Females play a larger role in determining paternity than previously thought, say biologists. The findings have major implications for the study of sexual selection, sexual conflict and the coevolution of male and female reproductive traits.

Scientists mated female flies with two groups of males, the latter of which were distinguished by green- and red-tagged sperm heads.
Credit: Image courtesy of Syracuse University

Females play a larger role in determining paternity than previously thought, say biologists in Syracuse University's College of Arts and Sciences. Their findings are the subject of a new paper titled "Female mediation of competitive fertilization success in Drosophila melanogaster," published this month by Proceedings of the National Academy of Sciences.

Related Articles


Stefan Lüpold, a research assistant professor in the college's Department of Biology and the paper's lead author, says the findings have major implications for the study of sexual selection, sexual conflict and the coevolution of male and female reproductive traits. "Our studies show that female flies don't just provide a static arena for sperm competition; they also influence who fathers their offspring," says Lüpold, a member of the Pitnick Lab, where the research took place. "This is indicated by various means, including the re-mating interval; progeny production rate; sperm-storage organ morphology; and the way females store and use sperm."

"Female mediation" was co-authored by Lüpold; Scott Pitnick and John Belote, biology professors at SU; Kirstin S. Berben, a SU lab technician; Mollie K. Manier, a SU research associate; and Cecilia S. Blengini, a Ph.D. student at the National University of Córdoba (Argentina), who worked in the Pitnick Lab for several months during the experiment.

Understanding postcopulatory sexual selection has traditionally been difficult, due to the challenge of observing events within the reproductive tracts of internally fertilizing species -- from those in organisms as small as a Drosophila fly to as large as a human. Discriminating sperm from different males also clouds the issue.

Lüpold and his team worked around these problems by mating female flies with two groups of males, the latter of which were distinguished by green- and red-tagged sperm heads. "The colored heads allowed us to better study the physical displacement of the 'resident' sperm by the second male from the female's storage organs. They also helped us witness the female's ejection of the sperm and the biased use of competing sperm for fertilization," says Pitnick, an expert in the evolution of reproduction. He and Lüpold discovered that the timing of the female ejection of sperm was genetically variable, and, thus, influenced the amount of sperm competing for fertilization. "The longer a female waited to eject the sperm, the more time it had to enter her storage organs and displace the sperm from her previous mate," says Pitnick.

Such work is de rigueur for the Pitnick Lab, known for its headline-grabbing research into evolution and sexual selection. In addition to postcopulatory sexual selection, the lab's foci include reproductive isolation, sperm behavior, life-history evolution and brain-size evolution.

"Because females of most species mate with multiple males within a reproductive cycle, intrasexual competition and intersexual choice can continue in the form of sperm competition and cryptic female choice," says Pitnick. "Our investigations have demonstrated that the morphology of the female reproductive tract, which is rapidly divergent, determines how females bias paternity in favor of particular sperm morphologies. In fact, complex ejaculate-female and sperm-female interactions are emerging as more the rule than the exception."

Lüpold says that such interactions underlie the coevolution of sperm-female tract traits observed in numerous taxa: "Giant sperm tails represent the cellular, postcopulatory equivalent of peacock tails, having evolved mainly through female sperm choice."


Story Source:

The above story is based on materials provided by Syracuse University. The original article was written by Rob Enslin. Note: Materials may be edited for content and length.


Cite This Page:

Syracuse University. "Sperm wars ruled by females? Females play active, pivotal role in postcopulatory processes." ScienceDaily. ScienceDaily, 10 June 2013. <www.sciencedaily.com/releases/2013/06/130610192951.htm>.
Syracuse University. (2013, June 10). Sperm wars ruled by females? Females play active, pivotal role in postcopulatory processes. ScienceDaily. Retrieved December 17, 2014 from www.sciencedaily.com/releases/2013/06/130610192951.htm
Syracuse University. "Sperm wars ruled by females? Females play active, pivotal role in postcopulatory processes." ScienceDaily. www.sciencedaily.com/releases/2013/06/130610192951.htm (accessed December 17, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Wednesday, December 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

When You Lose Weight, This Is Where The Fat Goes

When You Lose Weight, This Is Where The Fat Goes

Newsy (Dec. 17, 2014) — Can fat disappear into thin air? New research finds that during weight loss, over 80 percent of a person's fat molecules escape through the lungs. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) — NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Ivory Trade Boom Swamps Law Efforts

Ivory Trade Boom Swamps Law Efforts

Reuters - Business Video Online (Dec. 17, 2014) — Demand for ivory has claimed the lives of tens of thousands of African elephants and now a conservation report says the illegal trade is overwhelming efforts to enforce the law. Amy Pollock reports. Video provided by Reuters
Powered by NewsLook.com
Uphill Battle to Tackle Indonesian Shark Fishing

Uphill Battle to Tackle Indonesian Shark Fishing

AFP (Dec. 17, 2014) — Sharks are hauled ashore every day at a busy market on the central Indonesian island of Lombok, the hub of a booming trade that provides a livelihood for local fishermen but is increasingly alarming environmentalists. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins