Peering Into the Inner Workings of Evolution With Jellyfish Eyes

Red Eyed jellyfish

This tiny jellyfish known as Polyorchis pencillatus is known as red-eyed jellyfish. Its a number of eyes, known as ocelli, will be seen on the base of the tentacles and comprise light-sensing cells and purple pigment. Credit score: Anna Klompen

Some jellyfish have easy eyes; some have advanced ones. Different jellyfish don’t have any eyes in any respect. Certainly, latest analysis has proven jellyfish eyes in several species have developed individually and independently many instances in several methods over many millennia, making them a perfect mannequin to higher perceive how the trait expresses itself genetically.

Now, a crew of researchers that features Paulyn Cartwright, professor of ecology & evolutionary biology on the College of Kansas; Maria Pia Miglietta of Texas A&M College, Galveston; and lead principal investigator Todd Oakley of the College of California, Santa Barbara, has obtained a grant from the Nationwide Science Basis to review how jellyfish-eye “convergence” — duplicated occasions within the historical past of life — supplies a window on how evolution works at genetic, mobile and morphologic ranges.

The KU portion of the NSF grant totals $494,890.

“Eyes developed a number of instances independently throughout the jellyfish,” Cartwright stated. “We’ve identified for some time that there’s not a single origin of eyes in all animals however have been stunned at what number of instances they developed independently in jellyfish.”

Now, Cartwright and her collaborators plan a scientific “deep dive” into evolutionary patterns to find whether or not jellyfish use the identical or completely different points of their genetic toolkit to construct eyes each single time that they’ve developed.

The researchers plan to reconstruct an in depth phylogenomic tree of Medusozoa (a clade within the Cnidaria phylum) to hint the evolutionary historical past of jellyfish eyes and use comparative transcriptomes and single-cell RNA sequencing to determine similarities and differences in genetic pathways of convergent eyes.

“Jellyfish are a really nice system for this, because they have a diversity of eyes, ranging from simple clusters of light-sensing cells to very complex eyes — camera-type eyes that can form images and have a lens, a cornea and a retina — so superficially, they can look identical to vertebrates,” Cartwright said.

In her KU lab, she plans to analyze many species of jellyfish to determine all genes expressed in single cells of different jellyfish eyes and find what’s shared among different instances of jellyfish and what’s changed in their basic genetic building blocks.

“Cells themselves have their own characteristics, and they’re really an outcome of many, many different genes being expressed — so sometimes we might miss an overall pattern by looking at individual genes,” the KU researcher said. “But if we look at all the genes that are expressed at the cell and what that particular outcome is, that might give us a different level of information. That’s why it’s great to look at all those different levels and see what is similar and what’s changed to really help us understand this very complicated question. Jellyfish are a great system to do this because they’re so amenable to these types of experiments. We can look at individual genes and how they’re expressed; we can look wholesale at all the genes that are expressed in those cells; and then we can see what is similar at the morphological level between those and what’s different.”

Part of the work under the new NSF grant will include travel to Panama, a hotspot of jellyfish biodiversity, to collect specimens. Cartwright and her colleagues will use the fruits of their research to construct a more detailed phylogenetic tree, or evolutionary history, of jellyfish.

“Jellyfish are very diverse — there’s a few thousand species,” Cartwright said. “Uncovering their exact evolutionary history has been really challenging in part because a lot of this diversification happened over half a billion years ago. The other challenge is to sample these organisms. Many of them live in open-ocean environments in the deep sea, and some of them are incredibly small and hard to find. So, we’re looking at ancient divergence times within a diverse and difficult-to-sample group. This has been a challenge that I’ve been working on for at least the last 20 years of my career, so we’re really excited in the age of genomics because getting more data and being able to sequence more genes and throwing more DNA sequences at this problem is expected to be very promising at resolving some of these relationships amongst Cnidarians.”

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