Arka Pal is a biologist and a PhD student from the Barton group at the Institute of Science and Technology Austria (ISTA). He recently started down the fascinating path of a crossing deep into the heart of the Pyrenees. Alongside an international team of scientists, Pal recently published a groundbreaking study in the journal Molecular Ecology, which investigates the evolutionary dynamics of snapdragon flowers. This study unequivocally uncovers the significance of an important class of flower color genes. They provide a barrier between two different snapdragon strains, preventing hybridization.
This new study focuses on two hybrid zones within the Pyrenees, Avellanet and Planoles. Among these places, magenta-flowered magdalena and sunny-yellow golden arches snapdragons prosper shoulder-to-shoulder. Pal’s compares samples from these regions to shed light on the genetic underpinnings of speciation. His ultimate aim is to understand how variation between varieties springs from a shared ancestor and develops over time. Their field season allowed the team to collect over 5,000 samples. They documented plant growth and GPS locations with great precision to ensure accurate data collection.
The Significance of Flower Color Genes
In their recent article, Pal and others made an important observation. They showed that although there was a lot of genetic divergence between the two hybrid zones, the same seven genes controlling flower color were conserved in both hybrid zones. This is great news and an important finding! It’s an impressive example of how nature harnesses color genes to maintain snapdragon varieties unique, even when forced to live in the same environment.
“When we compared the Planoles and Avellanet hybrid zones, we found their genomes were quite different—they all had different mixtures of ‘words,’” – Arka Pal
Pal’s research highlights how critical these color genes are to shaping pollinator behavior. Magenta and yellow snapdragons have the same species of bees visiting them. These bees have fast learned to associate certain flower colors with sugar rewards. Bees are very attracted to the striking magenta blossoms that line one side of the habitat. Along the way, they discover the sunny yellow blossoms on the opposite side.
“The same [bee species] pollinates both the yellow and the magenta species. Bees learn where to go to find nectar. On the magenta side, they visit magenta flowers, while on the yellow side, they frequent yellow ones,” – Arka Pal
This dynamic is a perfect illustration of how color draws in pollinators. It helps ensure genetic purity of these two breeds.
Investigating Hybrid Zones
Pal refers to hybrid zones as “natural laboratories,” the only place in our world where we can study speciation and evolution in real-time. This new approach allows researchers to start isolating the effects of both natural processes shaping genetic variations. They can accomplish this without artificial interventions under controlled conditions like greenhouses.
“Hybrid zones are essentially ‘natural laboratories’ where you can study the process of speciation and evolution in nature, letting nature conduct the experiments for us instead of crossing them in greenhouses,” – Arka Pal
While conducting their research, Pal and their team traveled on foot through stunning vistas. From these, they obtained samples from 19 magenta and 19 yellow snapdragons in Avellanet, and from 18 magenta and 18 yellow specimens in Planoles. It was rough, and the terrain ranged from stunning mountain passes to daunting descents covered in even denser undergrowth with stinging nettles and prickly bushes.
“You could romanticize it and say we are hiking,” – Arka Pal”But Antirrhinum likes to grow in human-disturbed habitats, often alongside mountain roads. So, we walk these beautiful roads in the Pyrenees, sporadically climbing steep slopes through brambles and nettles to collect snapdragons,” – Arka Pal
Close-contact, hands-on fieldwork is critical for us to collect accurate genomic data. By studying the gene expression of snapdragons in nature, researchers are better able to assess how environmental factors influence which genes are expressed.
Advanced Techniques in Genomic Analysis
To address the massive dataset created from their samples, Pal used whole-genomic sequencing technology. This strategy provides an unprecedented view of the genomic landscape, enabling direct comparisons between the two hybrid zones. Through studying the genomes from these alternative forms of snapdragons, Pal hopes to shed light on how evolution influenced these localised populations of snapdragons through time.
Picture the genome as a messy encyclopedia without any punctuation. It’s packed with billions of letters that spell out thousands of words—our genes. Few major ‘words’ are essential to distinguish species or varieties,” – Arka Pal
Beyond the specific contributions, the insights gained from these analyses are invaluable for understanding the mechanisms of speciation. By pinpointing the underlying genes that cause the differences between the varieties, scientists can gain a deeper understanding of the evolutionary forces involved.