According to a classic definition of species , two animals belong to to the same species if they can make babies that can finally go on to make their own . Sometimes different species get it on and produce offspring , but hybrids like mules are almost always sterile because of genomic inconsistency . And then there ’s the gruesome case of killer nematode sperm cell , which crawl through the physical structure of females from a dissimilar metal money , destroying ovaries and murder tissue paper .
A squad led byAsher Cutter from University of TorontoandEric Haag from University of MarylandmatedCaenorhabditisworms from about 10 different species . These admit hermaphrodites who produce their own sperm to fertilize their own eggs . The lifespan of female and hermaphrodites mated with males from different species were drastically come down compare with female person mat up with the same coinage . Furthermore , females who survived cross - species pairing were often sterile , even when they were afterward mated with their own coinage .
The squad examined the sterile and die females and hermaphrodite under a microscope using a fluorescent stain to project the spermatozoan . That ’s when they discovered that the foreign sperm had kick downstairs through the uterus in an endeavor to fertilize the ballock . After invading the ovaries , the sperm put down them , lead the worm unfertile . Then the sperm travels through the physical structure , do tissue impairment and eventually end .
" Punishing crown of thorns - species mating by sterility or last would be a powerful evolutionary way to sustain a species barrier , " Haag explains in anews release . Sperm and female generative tract interactions are a novel reason for failed union , and similar coordination problem could explicate infertility in other animals . Theworkwas print inPLOS Biologythis week .
Killer sperm may be the result of divergence in dirt ball sex evolution . If a female mates with more than one male , the sperm physically compete with each other for access to the egg . For her part , the female must be able to withstand this fierce jostling . “ It can sprain into kind of an munition race between males and females,”Cutter narrate Washington Post . “ And it make this chain reaction of evolutionary change , which can go in really dissimilar directions for unlike species . ”
The activity of sperm – and the power of the uterus to tolerate it – might be specific to metal money . What may have happened here is that , a female from a species with soft sperm felt up with a coinage with more fast-growing sperm . But without cistron menstruation , there are no long term consequence .
In the most extreme example , whenC. nigonimales were breed withC. briggsaehermaphrodites , 95 percent of the parental worms became sterile . " The two species are very close in evolutionary terms , yet when they mate all hell fracture loose,“Haag tells New Scientist . While males checkmate indiscriminately , the intersex sensed and even tried to avoid males from harmful species . " epicene become very vulnerable to meeting with relatives that still do it the old way,“he adds . Though even the most harmful crosses raise some viable loan-blend .
persona : Gavin Woodruff ( top ) , Janice Ting ( middle )
