Featured Research

from universities, journals, and other organizations

Population density and testes size: more than meets the eye

Date:
August 13, 2014
Source:
University of Lincoln
Summary:
Changes in population density can affect the size of animals’ testes and therefore impact on reproduction, researchers have found. Across the animal kingdom, there is usually a positive relationship between sperm competing to fertilize eggs and the male reproductive effort in producing large ejaculates. This usually manifests in males evolving larger testes. However, demographic and ecological processes may drastically alter the level of sperm competition and therefore the evolution of testes size, it turns out.

A team of researchers have discovered that changes in population density can affect the size of animals' testes and therefore impact on reproduction.

Related Articles


Across the animal kingdom, there is usually a positive relationship between sperm competing to fertilize eggs and the male reproductive effort in producing large ejaculates. This usually manifests in males evolving larger testes.

However, demographic and ecological processes may drastically alter the level of sperm competition and therefore the evolution of testes size.

A study has been conducted to find out whether testes size responds to natural fluctuations in density of 5 species of wild promiscuous voles.

The results have been published in Proceedings of the Royal Society B: Biological Sciences.

Females of many species mate with multiple males within a single reproductive cycle. When the sperm of two or more males compete for fertilisation, selection acts on a number of traits that enhance success such as sperm size and longevity. The number of sperm is key to success, which typically means males evolving larger testes.

Using long-term longitudinal data from five vole species in northern Finland, the team from the University of Jyvaskyla, Finland, University of Lincoln, UK, and the Finnish Forest Research Institute found that some species show the predicted increase in testes size with population density.

However, when density changed dramatically between years, this relationship can be reversed in some species.

Lead author Dr Ines Klemme from the University of Jyvaskyla, Finland, said: "Large changes in population density can affect competition not only for reproduction, but also for other resources such as space and food. These could potentially alter the ability of males to be able to produce reproductive tissue."

Co-author Dr Carl Soulsbury, from the School of Life Sciences, University of Lincoln, added: "Knowing if testes size can respond to rapid and large natural changes in sperm competition is an important evolutionary question. The results suggest our understanding of sperm competition in fluctuating populations is still very limited."


Story Source:

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


Journal Reference:

  1. Ines Klemme Carl D. Soulsbury And Heikki Henttonen. Contrasting effects of large density changes on relative testes size in fluctuating populations of sympatric vole species. Proceedings of the Royal Society B: Biological Sciences, August 2014 DOI: 10.1098/rspb.2014.1291

Cite This Page:

University of Lincoln. "Population density and testes size: more than meets the eye." ScienceDaily. ScienceDaily, 13 August 2014. <www.sciencedaily.com/releases/2014/08/140813103457.htm>.
University of Lincoln. (2014, August 13). Population density and testes size: more than meets the eye. ScienceDaily. Retrieved January 25, 2015 from www.sciencedaily.com/releases/2014/08/140813103457.htm
University of Lincoln. "Population density and testes size: more than meets the eye." ScienceDaily. www.sciencedaily.com/releases/2014/08/140813103457.htm (accessed January 25, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, January 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Florida Might Legalize Black Bear Hunting

Florida Might Legalize Black Bear Hunting

Newsy (Jan. 24, 2015) A string of black bear attacks has Florida officials considering lifting the ban on hunting the animals to control their population. Video provided by Newsy
Powered by NewsLook.com
Ebola Killing Large Portion Of Ape Population

Ebola Killing Large Portion Of Ape Population

Newsy (Jan. 23, 2015) Experts estimate Ebola has wiped out one-third of the world&apos;s gorillas and chimpanzees. Video provided by Newsy
Powered by NewsLook.com
Controversy Shrouds Captive Killer Whale in Miami

Controversy Shrouds Captive Killer Whale in Miami

Reuters - Light News Video Online (Jan. 23, 2015) Activists hope the National Oceanic and Atmospheric Agency (NOAA) will label killer whales endangered, allowing lawyers to sue a Miami aquarium to release an orca into the wild after 44 years. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
‘Healthy’ Foods That Surprisingly Pack on Pounds

‘Healthy’ Foods That Surprisingly Pack on Pounds

Buzz60 (Jan. 23, 2015) Some &apos;healthy&apos; foods are actually fattening. Fitness and nutrition expert John Basedow (@JohnBasedow) shines a light on the sneaky foods like nuts, seeds, granola, trail mix, avocados, guacamole, olive oil, peanut butter, fruit juices and salads that are good for you...but not so much for your waistline. Video provided by Buzz60
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