Featured Research

from universities, journals, and other organizations

Same-sex Behavior Seen In Nearly All Animals, Review Finds

Date:
June 17, 2009
Source:
University of California - Riverside
Summary:
Same-sex behavior is a nearly universal phenomenon in the animal kingdom, common across species, from worms to frogs to birds, concludes a new review of existing research.

A female-female pair of Laysan Albatross. Females cooperatively build nests and rear young when males are scarce.
Credit: Eric VanderWerf

Same-sex behavior is a nearly universal phenomenon in the animal kingdom, common across species, from worms to frogs to birds, concludes a new review of existing research.

Related Articles


"It's clear that same-sex sexual behavior extends far beyond the well-known examples that dominate both the scientific and popular literature: for example, bonobos, dolphins, penguins and fruit flies," said Nathan Bailey, the first author of the review paper and a postdoctoral researcher in the Department of Biology at UC Riverside.

There is a caveat, however. The review also reports that same-sex behaviors are not the same across species, and that researchers may be calling qualitatively different phenomena by the same name.

"For example, male fruit flies may court other males because they are lacking a gene that enables them to discriminate between the sexes," Bailey said. "But that is very different from male bottlenose dolphins, who engage in same-sex interactions to facilitate group bonding, or female Laysan Albatross that can remain pair-bonded for life and cooperatively rear young."

Published June 16 in the journal Trends in Ecology & Evolution, the review by Bailey and Marlene Zuk, a professor of biology at UCR, also finds that although many studies are performed in the context of understanding the evolutionary origins of same-sex sexual behavior, almost none have considered its evolutionary consequences.

"Same-sex behaviors—courtship, mounting or parenting—are traits that may have been shaped by natural selection, a basic mechanism of evolution that occurs over successive generations," Bailey said. "But our review of studies also suggests that these same-sex behaviors might act as selective forces in and of themselves."

A selective force, which is a sudden or gradual stress placed on a population, affects the reproductive success of individuals in the population.

"When we think of selective forces, we tend to think of things like weather, temperature, or geographic features, but we can think of the social circumstances in a population of animals as a selective force, too," Bailey said. "Same-sex behavior radically changes those social circumstances, for example, by removing some individuals from the pool of animals available for mating."

Bailey, who works in Zuk's lab, noted that researchers in the field have made significant strides in the past two and a half decades studying the genetic and neural mechanisms that produce same-sex behaviors in individuals, and the ultimate reasons for their existence in populations.

"But like any other behavior that doesn't lead directly to reproduction—such as aggression or altruism—same-sex behavior can have evolutionary consequences that are just now beginning to be considered," he said. "For example, male-male copulations in locusts can be costly for the mounted male, and this cost may in turn increase selection pressure for males' tendency to release a chemical called panacetylnitrile, which dissuades other males from mounting them."

The review paper:

Examines work done to test hypotheses about the origins of same-sex behavior in animals.

Provides a framework for categorizing same-sex behavior, for example, is it adaptive, not adaptive, occurs often, infrequently?

Discusses what has been discovered about the genetics of same-sex behavior, especially in the model organism, the fruit fly Drosophila, and in human beings.

Examines connections between human sexual orientation research, and research on non-human animals, and highlights promising avenues of research in non-human systems.

The reviewers expected the research papers they read for their article would give them a better understanding of the degree to which same-sex behaviors are heritable in animals.

"How important are genes to the expression of these behaviors, compared to environmental factors?" Bailey said. "This is still unknown. Knowing this information would help us better understand how the behaviors evolve, and how they affect the evolution of other traits. It could also help us understand whether they are something that all individuals of a species are capable of, but only some actually express."

Bailey recommends that fellow evolutionary biologists studying same-sex behavior in animals adopt some of the research approaches that have been successful in human studies.

"We have estimates, for example, of the heritability of sexual orientation in humans, but none that I know of in other animals," he said. "Scientists have also targeted locations on the human genome that may contribute to sexual orientation, but aside from the fruit fly, we have no such detailed knowledge of the genetic architecture of same-sex behavior in other animals."

Next in their research, Bailey and Zuk plan to begin experimentally addressing some of the many issues raised in their review.

Said Bailey, "We want to get at this question: what are the evolutionary consequences of these behaviors? Are they important in the evolution of mating behavior, or do they just add extra 'background noise'? We are pursuing work on the Laysan Albatross, in which females form same-sex pairs and rear young together. Same-sex behavior in this species may not be aberrant, but instead can arise as an alternative reproductive strategy."

The UCR Academic Senate funded the one-year study.


Story Source:

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


Journal Reference:

  1. Bailey et al. Same-sex sexual behavior and evolution. Trends in Ecology & Evolution, June 16, 2009

Cite This Page:

University of California - Riverside. "Same-sex Behavior Seen In Nearly All Animals, Review Finds." ScienceDaily. ScienceDaily, 17 June 2009. <www.sciencedaily.com/releases/2009/06/090616122106.htm>.
University of California - Riverside. (2009, June 17). Same-sex Behavior Seen In Nearly All Animals, Review Finds. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2009/06/090616122106.htm
University of California - Riverside. "Same-sex Behavior Seen In Nearly All Animals, Review Finds." ScienceDaily. www.sciencedaily.com/releases/2009/06/090616122106.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Cambodian Capital's Only Working Elephant to Retire in Jungle

Cambodian Capital's Only Working Elephant to Retire in Jungle

AFP (Nov. 25, 2014) Phnom Penh's only working elephant was blessed by a crowd of chanting Buddhist monks Tuesday as she prepared for a life of comfortable jungle retirement after three decades of giving rides to tourists. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Buzz60 (Nov. 24, 2014) A Swedish Adventure racing team travels to try and win a world title, but comes home with something way better: a stray dog that joined the team for much of the grueling 430-mile race. Jen Markham has the story. 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