Featured Research

from universities, journals, and other organizations

How Does One Sex Grow Larger Than The Other?

Date:
January 30, 2007
Source:
University of Chicago Press Journals
Summary:
In most arthropod groups females are larger and therefore grow faster, a pattern markedly different from primates and birds, which showed differences in growth period. One explanation of why females can grow faster is that, although it is generally cheaper to produce (small) sperm than (large) eggs, it may be costlier to produce male gonads and genitalia.

Argiope aurantia spiders.
Credit: Photo graph by Matthias W. Foellmer

Why are males larger than females in some animal species (such as most mammals), females larger than males in others (such as most insects), and why are the sexes alike in yet other species (such as several birds)? Further, how is such sexual size dimorphism achieved when it exists? If males and females grow at the same rate, then the larger sex has to extend its growth period. Alternatively, the larger sex can grow faster.

Related Articles


A group of 13 researchers from 10 countries investigated the latter questions using comparative data on 155 species of insects and spiders (arthropods) from 7 major groups. The results, published in the February issue of The American Naturalist, suggest that, generally, growth rate differences between the sexes are more important than growth period differences in mediating size dimorphism in arthropods. Nevertheless, depending on the species group, males and females tend to have equal growth periods (beetles and water striders), males have longer growth periods than females (two groups of flies), or males have shorter growth periods than females (so-called protandry), albeit not quite in proportion to the size difference between the sexes (spiders, butterflies, and Hymenoptera, i.e. bees, ants, wasps, and alike).

As in most arthropod groups females are larger, they must therefore generally grow faster, an interesting pattern markedly different from primates and birds, which were also analyzed and in which differences in growth period between the sexes were generally more dominant. Three potential explanations for why female arthropods can grow faster than males are discussed. The most intriguing of these explanations is that, although it is generally cheaper to produce (small) sperm than (large) eggs, it may be costlier to produce male gonads and genitalia than it is to produce female gonads and genitalia. As a result, males might need more time to mature at larger body sizes.

This world-wide collaboration developed because most people work and thus have data on only particular animal groups. Wolf Blanckenhorn of the Zoological Museum at the University of Zurich in Switzerland called together all these researchers to investigate this specific idea about the evolution of sexual size dimorphism that had occupied him for quite some time.

Founded in 1867, The American Naturalist is one of the world's most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research. AN emphasizes sophisticated methodologies and innovative theoretical syntheses--all in an effort to advance the knowledge of organic evolution and other broad biological principles.

Reference: Wolf U. Blanckenhorn, Anthony F. G. Dixon, Daphne J. Fairbairn, Matthias W. Foellmer, Patricia Gibert, Kim van der Linde, Rudolf Meier, Sφren Nylin, Scott Pitnick, Christopher Schoff, Martino Signorelli, Tiit Teder, and Christer Wiklund, "Proximate Causes of Rensch's Rule: Does Sexual Size Dimorphism in Arthropods Result from Sex Differences in Development Time?" The American Naturalist, volume 169 (2007), pages 245--257.


Story Source:

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


Cite This Page:

University of Chicago Press Journals. "How Does One Sex Grow Larger Than The Other?." ScienceDaily. ScienceDaily, 30 January 2007. <www.sciencedaily.com/releases/2007/01/070129192339.htm>.
University of Chicago Press Journals. (2007, January 30). How Does One Sex Grow Larger Than The Other?. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2007/01/070129192339.htm
University of Chicago Press Journals. "How Does One Sex Grow Larger Than The Other?." ScienceDaily. www.sciencedaily.com/releases/2007/01/070129192339.htm (accessed October 25, 2014).

Share This



More Plants & Animals News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) — Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) — Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) — One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) — Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
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