There are species that are exclusively female. For example, a certain Australian grasshopper. It is called Warramaba virgo. The offspring are born by parthenogenesis. That is, the egg becomes an embryo without being fertilized by a sperm. No males or sex are needed. So does the grasshopper that reproduces by cloning itself.
The species is believed to have arisen 250,000 years ago, according to ‘Science’. Giving up sex for so long did not affect their ability to reproduce. This is fascinating information about evolution.
The usual method of reproduction “increases a species’ genetic diversity and ecological success,” says Michael Kearney. He works at the University of Melbourne. In addition, it helps to purge a population of bad mutation combinations. In parthenogenetic species all members have virtually identical genes. They may be less able to adapt when the environment changes and accumulate bad mutations.
But the clonally reproducing grasshopper has no problem with this. It successfully spread from western to eastern Australia, unlike its sexual relatives. Its celibacy saves it from wasting time and effort looking for a mate.
“The species appears to have evolved from a single highly successful clone,” say the researchers. They analyzed the number and nature of mutations. They estimated that W. virgo evolved from a hybrid mating between two other grasshopper species more than 250,000 years ago.
Benefits of cloning
The parthenogene had no advantage over its parent species in a number of physiological traits. Nor heat and cold tolerance, metabolic rate, or the number and size of their eggs. Nor how long they take to mature and how long they live.
“With so many benefits of leaving sex, it is surprising that parthenogenetic species are not more common. This rarity is due to source constraints rather than rapid extinction,” Kearney points out. In other words, more species don’t give up sex because developing parthenogenesis must be very difficult.
Apparently, the clonally reproducing grasshopper will be with us for a long time to come.