Scientists at the University of Liverpool have found that male fruitflies experience a type of 'paranoia' in the presence of another male, which doubles the length of time they mate with a female, despite the female of the species only ever mating with one male.
Females in many species of animal have multiple mates and males have evolved particular reproductive characteristics to ensure their sperm are successful when in competition with the sperm of other males. Adaptations include physical traits that result in increased sperm count, as well as behavioural alterations such as mating with females for up to 21% longer than they normally would.
In types of fruitfly where the female only mates once, however, there is little need for competitive behaviour. The male is not expected to increase its reproductive efforts in response to competition, because it 'knows' that the female will be fertilised with its sperm only. Scientists at Liverpool, however, have found that once a male had been in contact with another male, it subsequently increased the length of time it mates with a female by 93%, even though the risk of the female being fertilised by another male was remote.
The study suggests a number of reasons for this apparent 'paranoid' behaviour. One possible explanation is that females do occasionally mate with more than one male, and the male responds to the possibility of this rare event by changing its reproductive behaviour. Another reason could be that the presence of a competitor prompts the 'fear' that a male is unlikely to obtain another mate and it therefore increases its reproductive efforts in order to keep the one female fertile with its sperm for the female's entire lifespan.
Dr Anne Lize, from the University's Institute of Integrative Biology, explains: "We already knew, from previous studies, that male insects evolve physical and behavioural characteristics to make them a stronger reproductive competito
|Contact: Samantha Martin|
University of Liverpool