Featured Research

from universities, journals, and other organizations

A Boy For Every Girl? Not Even Close: Scientists Trace Evolution Of Butterflies Infected With Deadly Bacteria

Date:
September 11, 2009
Source:
Cell Press
Summary:
In a perfect world, for every boy there would of course be a girl, but a new study shows that actual sex ratios can sometimes sway very far from that ideal. In fact, the male-to-female ratio of one tropical butterfly has shifted rapidly over time and space, driven by a parasite that specifically kills males of the species, reveals a new report.

A male Great Eggfly (Hypolimnas bolina).
Credit: Courtesy of Wikimedia Commons

In a perfect world, for every boy there would of course be a girl, but a new study shows that actual sex ratios can sometimes sway very far from that ideal. In fact, the male-to-female ratio of one tropical butterfly has shifted rapidly over time and space, driven by a parasite that specifically kills males of the species, reveals a report published online on September 10th in Current Biology, a Cell Press publication.

"We were surprised at the speed with which change in sex ratio could occur," said Emily Hornett of the University of Liverpool. "Between 1886 and 1894 in Fiji, the male-killing bacterium rose from 50 percent to over 90 percent frequency, changing the sex ratio from 2:1 to 10:1."

The researchers made their discovery by applying modern tools to aging museum collections of the butterfly known as Hypolimnas bolina. Between the 1870s and 1930s, these insects' highly variable female wing color pattern led traveling entomologists to intensively collect them. Many specimens were later deposited in museums along with detailed field notes.

The researchers examined the variation in the butterflies' sex ratios and their infection with the male-killing Wolbachia bacterium by assaying museum specimens, inferring from that what historical populations must have been like. Comparison of contemporary and museum samples revealed profound change in four of five populations examined, the researchers report.

Two populations became extremely female-biased as the male-killing bacterium spread. One population evolved from extremely female-biased to a sex ratio near 50:50 after the infection lost its male-killing activity. The final population fluctuated widely in sex ratio, along with changes in the frequency of the male-killer.

These findings give new insight into the reproductive ecology of the butterflies. More importantly, they show how scientists can literally watch evolution in action by comparing museum specimens to contemporary populations, highlighting the incredible value of such collections as "silent witnesses" to such change.

"Evolution can be observed by comparing fossil and current species, or inferred from variation between extant species placed on a phylogeny," the researchers wrote. "However, it is rare to directly observe evolution over short time periods. Traditionally, direct observation of evolution has required records over time from long-term study populations. Resurrection ecology, where viable propagule stages of known age are retrieved from sediment cores and compared to current specimens, represents a new technique with which to observe evolution directly. However, both of these approaches are obviously limited to the few species for which this type of data or sample is available.

"We predict that the increasing availability of methods that make DNA from museum specimens accessible will lead to an escalating use of such collections to answer evolutionary questions. With the advent of high-throughput DNA sequencing, the worth of museum collections to future generations of evolutionary biologists is invaluable and inestimable."

The researchers include Emily A. Hornett, University of Liverpool, Liverpool, UK; Sylvain Charlat, University of Lyon, Villeurbanne, France; Nina Wedell, University of Exeter, Penryn, UK; Chris D. Jiggins, University of Cambridge, Cambridge, UK; and Gregory D.D. Hurst, University of Liverpool, Liverpool, UK.


Story Source:

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


Cite This Page:

Cell Press. "A Boy For Every Girl? Not Even Close: Scientists Trace Evolution Of Butterflies Infected With Deadly Bacteria." ScienceDaily. ScienceDaily, 11 September 2009. <www.sciencedaily.com/releases/2009/09/090910121801.htm>.
Cell Press. (2009, September 11). A Boy For Every Girl? Not Even Close: Scientists Trace Evolution Of Butterflies Infected With Deadly Bacteria. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2009/09/090910121801.htm
Cell Press. "A Boy For Every Girl? Not Even Close: Scientists Trace Evolution Of Butterflies Infected With Deadly Bacteria." ScienceDaily. www.sciencedaily.com/releases/2009/09/090910121801.htm (accessed September 16, 2014).

Share This



More Plants & Animals News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Ivorians Abandon Monkey Pets in Fear Over Ebola Virus

Ivorians Abandon Monkey Pets in Fear Over Ebola Virus

AFP (Sep. 16, 2014) Since the arrival of Ebola in Ivory Coast, Ivorians have been abandoning their pets, particularly monkeys, in the fear that they may transmit the virus. Duration: 00:47 Video provided by AFP
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