Featured Research

from universities, journals, and other organizations

Infidelity Produces Faster Sperm, Swedish Fish Study Finds

Date:
January 24, 2009
Source:
Uppsala University
Summary:
Until now, it has been difficult to prove that fast-swimming sperm have an advantage when it comes to fertilizing an egg. But now Swedish researchers can demonstrate that unfaithful females of the cichlid fish species influence the males' sperm.

Until now, it has been difficult to prove that fast-swimming sperm have an advantage when it comes to fertilizing an egg. But now a research team can demonstrate that unfaithful females of the cichlid fish species influence the males' sperm.
Credit: iStockphoto/Serdad Yagci

Until now, it has been difficult to prove that fast-swimming sperm have an advantage when it comes to fertilizing an egg. But now a research team at Uppsala University can demonstrate that unfaithful females of the cichlid fish species influence the males’ sperm. Increased competition leads to both faster and larger sperm, and the research findings now being published in the scientific journal PNAS, Proceedings of the National Academy of Sciences, thus show that the much mythologized size factor does indeed count.

Related Articles


“The competition among sperms to fertilize a female’s eggs is an extremely powerful evolutionary force that influences various characteristics of sperms, such as size and speed,” says Niclas Kolm, a researcher at Uppsala University, who, in collaboration with scientists from several other universities, has studied the mating system of 29 species of Tanganyika cichlids. “For the first time, we can show a strong link between the degree of sperm competition and the size and speed of the sperms. Males with promiscuous females develop faster and larger sperms than the monogamous species,” says Niclas.

"In promiscuous species we found that males produced larger and faster sperm than in closely related species that were monogamous," says Sigal Balshine, associate professor in the department of Psychology, Neuroscience & Behaviour at McMaster University, and senior author on the study. "This research offers some of the first evidence that sperm has evolved to become more competitive in response to females mating with multiple males."

Female promiscuity is a major problem for males because the sperm from rival suitors will compete in the race to procreate, explains Balshine. While the idea that sperm would evolve to become more competitive when males compete for fertilization seems obvious, to date there has been little evidence to support this theory.

“[One] unique aspect of the study is that we based our study on an unusually large base, with many fish from many different species. The fish were caught in lakes in Africa, and a special characteristic of this group of fishes is that there are incredible numbers of species,” says Niclas. “There’s an unbelievable variety of species and different kinds of mating behaviors. There’s the whole spectrum of mating systems, from monogamous males to females that mate with many many males.”

The findings also show that the speed and the size of sperm are closely related: larger sperms are faster. These sperm swim faster thanks to the greater power of a larger flagellum, but faster sperm also need to have a larger store of energy, which in turn results in larger sperm.

Thanks to new analytical methods, they have also managed to demonstrate the order of this development. The sperm first become faster, then larger, following increased female promiscuity in a species.

“No one has previously been able to show what causes what. Here we can clearly see that female promiscuity determines the character of sperms,” says Niclas.


Story Source:

The above story is based on materials provided by Uppsala University. Note: Materials may be edited for content and length.


Cite This Page:

Uppsala University. "Infidelity Produces Faster Sperm, Swedish Fish Study Finds." ScienceDaily. ScienceDaily, 24 January 2009. <www.sciencedaily.com/releases/2009/01/090121093339.htm>.
Uppsala University. (2009, January 24). Infidelity Produces Faster Sperm, Swedish Fish Study Finds. ScienceDaily. Retrieved January 31, 2015 from www.sciencedaily.com/releases/2009/01/090121093339.htm
Uppsala University. "Infidelity Produces Faster Sperm, Swedish Fish Study Finds." ScienceDaily. www.sciencedaily.com/releases/2009/01/090121093339.htm (accessed January 31, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, January 31, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

CDC: Get Vaccinated for Measles

CDC: Get Vaccinated for Measles

Reuters - US Online Video (Jan. 30, 2015) The CDC is urging people to get vaccinated for measles amid an outbreak that began at Disneyland and has now infected more than 90 people. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Obama To Outline New Plan For Personalized Medicine

Obama To Outline New Plan For Personalized Medicine

Newsy (Jan. 30, 2015) President Obama is expected to speak with drugmakers Friday about his Precision Medicine Initiative first introduced last week. Video provided by Newsy
Powered by NewsLook.com
NFL Concussions Down; Still on Parents' Minds

NFL Concussions Down; Still on Parents' Minds

AP (Jan. 30, 2015) The NFL announced this week that the number of game concussions dropped by a quarter over last season. Still, the dangers of the sport still weigh on players, and parents&apos; minds. (Jan. 30) Video provided by AP
Powered by NewsLook.com
U.S. Wants to Analyze DNA from 1 Million People

U.S. Wants to Analyze DNA from 1 Million People

Reuters - US Online Video (Jan. 30, 2015) The U.S. has proposed analyzing genetic information from more than 1 million American volunteers to learn how genetic variants affect health and disease. Rough Cut (no reporter narration). Video provided by Reuters
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


Health & Medicine

Mind & Brain

Living & Well

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