How did pumpkins evolve to be so rare? Biologists think they know why.

They can be two pounds or 200, small and spherical or misshapen and oblong, and exhibit a variety of colors, coats, and patterns. No, we’re not talking about dogs, but pumpkins, another genetically malleable life form that comes in a wide and bizarre variety of sizes and shapes, most of which can (again, like dogs) interbreed with each other despite to be so radically different. That genetic malleability is unique in the plant world: Apples, tomatoes, and oranges have a lot of genetic variation, but not three orders of magnitude differences in mass like pumpkins.

These genetic oddities have a concomitant range of uses among humans: culinary, decorative, and musical. The pumpkins have spicy seeds that can be transformed into a snack or oil; yellow squash can be cooked in a savory pasta sauce; Y bottle gourds with trendy warts They are a traditional home decoration, especially during this time of year.

Genetically speaking, this is a remarkable plant. So what is going on with pumpkins to allow for such incredible natural variation? And what makes them so bizarre biologically, compared to other plants?

The evolutionary history of pumpkins intersects with human history, with our beloved plants changing as civilization changed. It could even be argued that, in a sense, the pumpkin variety is a testament to both human ingenuity and the wonders of the natural world.

“The origin of these crops, which plays a very important factor in terms of the diversity of forms and genetics.”

Taxonomically, gourds belong to a family known as Cucurbits — And, as Dr. Ajay Nair, chair of the Graduate Program in Sustainable Agriculture at Iowa State University, told Salon, there are three main reasons why pumpkins are so genetically diverse that they have been bred into subspecies as diverse as giant pumpkins Y watermelons.

“If you look at the origin of the crops, where these crops originated, that plays a huge factor in terms of diversity of forms and genetics,” Nair said, such as gourds from South America or snake gourds from India. . He also pointed out that pumpkins have a lot of diversity in their gene pool: cucumbers only have 7 haploid chromosomes, while watermelons have 11 different chromosomes.

Finally, there is human intervention: “These crops have been around for a long time and humans have interacted with them. There have been a lot of very direct ways to select these crops, domesticate them and improve them,” Nair. he says.

Sometimes these factors complement each other, as when humans take advantage of the infertility of pumpkins to Breed Specialized Designer Pumpkins. However, human domestication sometimes limits the genetic diversity of pumpkins, as Heather R. Kates of the University of Florida Institute of Genetics explained.

“When we compare one of the pumpkin species that exhibits a great diversity of shapes, sizes, colors, and textures (the biggest pumpkin) to a species that does not (Cucurbita argyrosperma), species that have different shapes, sizes, colors and textures do not appear to have experienced the ‘domestication bottleneck’ or reduced genetic diversity that characterizes many crops,” Kates noted. In other words, species of cultivated pumpkins that have a lot of variety did not see their genetic variety cut by domestication in the same way that other commonly used crops like corn and bananas. While archaeologists cannot determine with certainty to what extent past human civilizations altered unwittingly the genetics of pumpkins for their own purposes, it is plausible to suspect that this happened quite a bit.

“We can’t know for sure what is responsible for the genetic or even archeological patterns we see in pumpkins, but we do have evidence that humans thousands of years ago continued to interbreed or allowed early types of domesticated pumpkins to interbreed with wild species. “. Kates explained. That, she says, allowed for the development of numerous types of pumpkins.

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Human intervention in pumpkin farming remains strong. Last year South African researchers published an article in Frontiers in Sustainable Food Systems magazine about the latent potential in bottle gourds. They noted that pumpkins could be an essential crop for food security, but it hasn’t been researched enough.

“There is wide genetic variation among African bottle gourd genetic resources” that can be used for everything from creating better products to improving marketing, the authors wrote. “However, the crop is poorly researched and used, and improved varieties have not yet been developed and commercialized in the region.”

“Plant pathogens are expected to spread and infect plants more easily under current climate change scenarios.”

In addition to being little studied, pumpkins may also be endangered by humanity’s ecological irresponsibility. As with so many other things, climate change may end up affecting humanity’s appetite for pumpkins. Of supercharged hurricanes Y intensifying supply chain disruptions possibly even fueling pandemics, the continued warming of Earth’s climate is altering our planet for the worse in countless ways. In that sense, as Kates noted, climate change will “intensify” the challenges facing pumpkin growers and gardeners.

“Some plant pathogens are expected to spread and infect plants more easily under current climate change scenarios, and environmentally stressed squash and squash are more susceptible to initial infection and subsequent development. of Diseases,” Kates, who is also a postdoctoral researcher at the Florida Museum of Florida. Natural history, she pointed out. “Changes in precipitation also pose a threat to Pumpkinespecially winter squash and squash cultivars that require high water input and bear fruit that are vulnerable to rot as they mature.” At the same time, “there are characteristics of the Cucurbita crop that can make it resilient to climate change,” like the fact that they are pollinated by more types of bees, the fact that there is such a diverse range of cultivated types, and the fact that they are versatile enough to grow in a wide range of temperatures and elevations.

This is good news for lovers of pumpkins, gourds, and melons, especially since holidays like Thanksgiving make pumpkins even more important. As Nair explained when asked about his favorite pumpkins, tastes and trends change over time.

“I think there’s been a shift towards smaller, more decorative pumpkins or zucchini that people can put on a plate or in front of their house,” Nair mused. “I like that. I like those pumpkins just because they have a different hue, a different palette, a different texture. Not just those big pumpkins, but different shapes, different sizes, maybe sometime even different colors on the same pumpkin. I like those pumpkins.”

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