• UCSBgauchos twitter avatar
    UCSB Wins Second Straight, Cruise Past Hawaii 7-0 https://t.co/amzRBbW6KM
    10 hours 44 min ago
  • ucsantabarbara twitter avatar
    Professor Pai of UCSB’s EACS is more than an expert in modern Chinese literature — he practically invented it! https://t.co/53lmKBy2Dk
    12 hours 40 min ago
  • UCSBgauchos twitter avatar
    Gauchos Blank San Diego State 7-0 to Open 2017 Dual Season https://t.co/KR324kOkWZ
    1 day 8 hours ago
  • UCSBgauchos twitter avatar
    Gauchos Storm Back From 15 Down in 2nd Half, Beat Mustangs 58-53 https://t.co/qj5Fipu1ql
    1 day 8 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball find a way to make 3s late for the comeback win against Cal Poly!
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball BEATS RIVAL CAL POLY 58-51!!! Alex Hart with 15 points and 11 rebounds!!
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball leads 58-51 with 25.5 seconds. Gabe Vincent sinks two clutch free throws to put the Gauchos ahead by 7
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    BIG TIME 3 BY CLIFTON POWELL JR PUTS THE GAUCHOS UP BY 6 WITH 48.8 SECONDS LEFT IN THE GAME
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball leads Cal Poly 55-49 with 1 minute to play!!!!
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball up against Cal Poly 50-46 with 4 minutes left in the game. Alex Hart leads the way with 15 points and 11 rebounds
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball GOES ON A RUN TO TIE THE GAME 46-46 WITH 6 MINUTES LEFT IN THE GAME.
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball goes on a run to cut the lead to 7 with 7:48 left in the game. Alex Hart leads all scorers with 13 points
    1 day 10 hours ago
  • UCSBgauchos twitter avatar
    @UCSBbasketball down 32-41 against Cal Poly with 11:34 in the game. Alex Hart leads the way with 13 points for the Gauchos
    1 day 11 hours ago
  • UCSBgauchos twitter avatar
    Cal Poly extends their lead to 13 with 16:16 left in the game. Cal Poly 39 UCSB 26
    1 day 11 hours ago
  • UCSBgauchos twitter avatar
    Gauchos shooting a mere 34.55% from the field to Cal Poly's 52.2%
    1 day 11 hours ago

UCSB Scientists Show that Female Fruit Flies Can be ‘Too Attractive' to Males

Monday, December 7, 2009 - 16:00
Santa Barbara, CA

Females can be too attractive to the opposite sex –– too attractive for their own good –– say biologists at UC Santa Barbara. They found that, among fruit flies, too much male attention directed toward attractive females leads to smaller families and, ultimately, to a reduced rate of population-wide adaptive evolution.

In an article published in the December 8 issue of Public Library of Science Biology, the authors described their experiments on the sex lives of fruit flies.

"Can females be too good looking?" asks William Rice, biology professor at UCSB. "Can there be disadvantages to being attractive? The answer is yes: If you are too attractive, you get too much male attention, and that interferes with your ability to function biologically."

The authors explain that the term "good looking," among fruit flies, refers to something, like a large body. From the perspective of a male fly, a desirable mate is a female that is larger and can therefore produce more offspring.

"These larger females are disproportionately courted and harassed by males attempting to obtain matings," said Tristan A. F. Long, the study's first author. "When these males are ‘choosy' with their courtship, there may be negative consequences to the species' ability to adaptively evolve."

According to the scientists, too much mating is harmful to the females because seminal fluid from the male has toxic side effects. Too much courtship can also hinder the female's ability to forage effectively.

"When they court the females, the males sing to them; they do this by vibrating their wings," said Rice. "They dance and sing at the same time. This might sound romantic, and it would be if it only happened once. But males are doing it all the time. This courtship is unrelenting –– like mosquitoes on a warm summer night –– as the male fruit flies try to persuade females to mate. The males are so persistent that they get them to mate almost every day."

In many species, females are frequently subject to intense courtship "harassment" from males attempting to obtain additional matings, according to the researchers. These coercive activities can result in attractive females becoming less fit to reproduce –– a factor that has a major effect on the entire population.

"We found that when harmful courtship behaviors were directed predominantly toward larger females of greater fecundity potential –– and away from smaller females, of lesser fecundity potential –– this resulted in an overall reduction in the variation of lifetime reproductive success of females in the population," said Long.

The male-mediated, persistent courtship bias can have important consequences for the ability of a population to adaptively change over time. If, for example, a female acquires a mutation that increases metabolic efficiency, allowing her to grow larger, and produce more offspring over her lifetime, this mutation should rapidly spread through the population. However, if the males get in the way of the biological success of these more attractive females, the mutation won't spread through the population as well as it might if males courted females indiscriminately.

The experiments clearly showed that the evolutionary adaptation of fruit flies is hindered by this mating situation. "This change in the distribution of fitness represents a previously unappreciated aspect of sexual selection –– one with important implications for the ability of beneficial genetic variation to spread through the gene pool, and ultimately for a species' capacity to adaptively evolve," Long explained.

Long was a Natural Sciences and Engineering Research Council of Canada (NSERC) postdoctoral fellow at UCSB at the time that he carried out the experiments designed with Rice. Long is currently a postdoctoral fellow with the University of Toronto in the Department of Ecology and Evolutionary Biology. The other authors are Alison Pischedda, a graduate student, and Andrew D. Stewart, a postdoctoral fellow, both of UCSB.

William Rice
PLoS Biology