Featured Research

from universities, journals, and other organizations

Shorebirds prefer a good body to a large brain

Date:
July 18, 2013
Source:
Plataforma SINC
Summary:
In many animal species, males and females differ in terms of their brain size. The most common explanation is that these differences stem from sexual selection. But predictions are not always certain. Scientists have discovered that a group of coastal birds, shorebirds, do not choose their mates by brain size but "on their physiques".

In the African Jacana (Actophilornis africanus), the female mates with several males and it is the males who raise offspring.
Credit: Daniel Sol

In many animal species, males and females differ in terms of their brain size. The most common explanation is that these differences stem from sexual selection. But predictions are not always certain. A team of researchers at the Centre for Ecological Research and Forestry Applications has discovered that a group of coastal birds, shorebirds, do not choose their mates by brain size but "on their physiques."

Some authors have suggested that sexual selection could promote brain enlargement in males, in other words, that females prefer males with more developed cognitive abilities. Others, however, have suggested that females should have larger brains because they are generally the sex that raises offspring.

"In this study we ask what role sexual selection plays in the brain size evolution of a group of birds, namely shorebirds. This group's choices are not random, as this family shows great diversity in its mating systems. This makes them an excellent model to study to research the role of sexual selection on brain size evolution," Daniel Sol, a researcher at the Spanish National Research Council (CSIC) in the Centre for Ecological Research and Forestry Applications (CREAF) and co-author of the study published in the Journal of Evolutionary Biology, explains.

The study, which analysed over 180 species, revealed a "surprising" fact to the researchers: polyandrous species -- those in which one female mates with various males -- have smaller brains relative to their bodies than monogamous and polygynous species, in the latter of which a male mates with several females.

"These results contradict many theories which suggest that sexual selection has played an important role in brain size evolution because if this were the case, polygynous species would also present sexual dimorphism -- different sizes between males and females -- but according to our analysis, this is not the case," the CREAF researcher continues.

"So we might ask ourselves the question: why do polyandrous species have smaller, more dimorphic brains? The answer is that we don't know. However, in the study we present some results that suggest a possible explanation: that sexual selection might have acted by increasing body size in females instead of reducing their brains."

The conclusion: the scientists have found that in this family of birds, body size evolves much more quickly than brain size. As brain size is measured relative to body size, increased body size leads to a reduction in relative brain size.

A bigger brain is not needed to take care of children

This study also negates another widespread idea: that parental care requires greater cognitive abilities and thus relatively larger brains.

"If this were the case, females of polygynous species would have larger brains than males because they have to look after their offspring. In reality, however, males and females don't differ in the relative sizes of their brains," Sol clarifies.

Finally, the fact that polygynous species do not have smaller brains than monogamous species negates the "social intelligence" hypothesis, which speculates that brain size has increased in species in which relations between partners or group members are more complex and require greater cognitive abilities.

According to the expert, this is due to the fact that in monogamous species, in which the male and female continually interact and have to coordinate with each other to raise offspring, sexual relationships are expected to be more complex than in polygynous species.

"We must tread carefully when deducing that differences in sexual dimorphism in brain size are due to sexual selection. With the evidence we have to date, we cannot conclude that sexual selection has been a significant force in brain size evolution," Sol emphasises.


Story Source:

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


Journal Reference:

  1. G. E. Garcνa-Peρa, D. Sol, A. N. Iwaniuk, T. Szιkely. Sexual selection on brain size in shorebirds (Charadriiformes). Journal of Evolutionary Biology, 2013; 26 (4): 878 DOI: 10.1111/jeb.12104

Cite This Page:

Plataforma SINC. "Shorebirds prefer a good body to a large brain." ScienceDaily. ScienceDaily, 18 July 2013. <www.sciencedaily.com/releases/2013/07/130718100933.htm>.
Plataforma SINC. (2013, July 18). Shorebirds prefer a good body to a large brain. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2013/07/130718100933.htm
Plataforma SINC. "Shorebirds prefer a good body to a large brain." ScienceDaily. www.sciencedaily.com/releases/2013/07/130718100933.htm (accessed July 29, 2014).

Share This




More Plants & Animals News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) — West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) — Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) — The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) — A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
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