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.

“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 September 19, 2014 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 September 19, 2014).

Share This



More Health & Medicine News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com
How The 'Angelina Jolie Effect' Increased Cancer Screenings

How The 'Angelina Jolie Effect' Increased Cancer Screenings

Newsy (Sep. 19, 2014) Angelina's Jolie's decision to undergo a preventative mastectomy in 2013 inspired many women to seek early screenings for the disease. Video provided by Newsy
Powered by NewsLook.com
The Cost of Ebola

The Cost of Ebola

Reuters - Business Video Online (Sep. 18, 2014) As Sierra Leone prepares for a three-day "lockdown" in its latest bid to stem the spread of Ebola, Ciara Lee looks at the financial implications of fighting the largest ever outbreak of the disease. 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:
from the past week

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