Have you ever marvel how it is that plant avoid pollinating themselves?Walnut treeshave develop to deflect this by fork their male and female flowers in time , with the flowers of one gender flower first , and the other coming second .

Walnut Tree can differ in whether they moderate with female flowers or virile flowers , and we ’ve known about this sinceCharles Darwinnoted it back in 1877 . It ’s been observed among domesticated walnut tree trees as well as their barbarian relatives , among which the ratio of female - first to male person - first is about 1:1 .

It was n’t until the eighties that we learned it all came down to a single transmitted locus , as discover by UC Davis graduate student Scott Gleeson , but we still had much to find out about how it all worked .

“ Walnuts and pecan have a secular dimorphism where they switch male and female flowering through the season , ” say Jeff Groh , graduate student in population biology at UC Davis and first author on a new report , in astatement . “ It ’s been cognise since the 1800s but has n’t been read at the molecular story before . ”

Groh and colleagues ’ study has popped the hood on sex conclusion in the Juglandaceae tree menage , which encompasses walnut , hickory , and pecan . With the helper of Professor Graham Coop of the Department of Evolution and Ecology , they gathered data from the UC Davis walnut breeding program , as well as nonmigratory Northern California disastrous walnut trees on campus .

They work out which one were female- and male - first , then sequence their genome to explore for normal associate with the trait . Doing so revealed that for walnuts , there are two variate of that gene Gleeson place that can tempt what sex goes first during flowering . They spot it in at least nine species of walnut , and found that it has been a unchanging system for a staggeringly recollective time , about 40 million year .

The study also look at pecan trees and discovered that they too have a flowering strategy that ’s controlled by a distinguishable genetic realm , but in a different area of the genome to walnut Tree . For pecan it acquire around 10 million old age earlier , and may be an example of convergent evolution whereby an ancient partake ascendant kicked off the trend and over prison term the accurate genetic mechanism changed slenderly .

What ’s more , the system seems to exploit in favor of keeping that 1:1 Libra between female- and male - first trees , as when one becomes more uncouth , the other get ahead a mating reward , take down the playing field . And if that vocalise conversant , that ’s because it is .

“ It ’s pretty atypical to keep variation over such a long clip , ” Groh said , and “ there ’s a clean parallel to a common mode of sex determination . ”

The system that keeps female- and male - first walnut trees in their 50:50 Libra the Scales is like to the way animal sexuality chromosome study . We humans ( as well as other mammalian ) have two structural variants , XTC andY chromosomes , that are kept around in balance by the room a boom in one influence the mating potential of the other .

So , the next time you ’re out walking and you see a walnut tree Sir Herbert Beerbohm Tree , give it a nod . We are more likewise than we realize .

The subject field is print in the journalScience .