Himalayan uplift caused diversity of ginger lily plants

Photographs of some of the Hedychium spp. Photo credits: (C) Ajith Ashokan, TrEE Lab

Researchers from the Indian Institute of Science Education and Research, Bhopal, explored how the various species of Rufous Lily (Dolan champā in Hindi) emerged as seen today from their ancestors through the changing geographical and climatic factors in India and neighboring countries. Based on DNA sequence analysis, they Pin up that the uplift of the Himalayas and the origin of the monsoon in the Indian subcontinent greatly influenced the way these lilies diversified into many species which were then able to colonize different places near and far. They found that Rufous Lilies may have originated in the northern region of Indo-Burma and spread to other parts of the world including Northeast India and the Western Ghats. The study was published in Molecular phylogenetics and evolution.

Studying past and present organisms and the relationships between them helps researchers understand why and how animals and plants are so diverse. Plant diversity is important because it ensures a variety of plant products, controls erosion, regulates pests and pathogens, and maintains soil fertility.

Ginger Lily is a flowering plant that bears fragrant white flowers. Several species of the plant are found in the northeastern states of India, Meghalaya, Manipur and Nagaland, southwestern China and northern Thailand. However, only six species are found in the Western Ghats of India. To understand the origin and diversity of rufous lilies, researchers collected plant samples from the Himalayas, Myanmar, China and the Malay Archipelago (the largest group of islands near Indonesia and the Philippines), as well as herbaria and museums in different parts of the world. They obtained DNA sequences from these samples. Using bioinformatics, they constructed a schematic representation of the evolutionary relationships (phylogenetic tree) between different species of Rufous Lily around the world.

The phylogenetic tree showed that rufous lilies originated in the Indo-Burmese region and then dispersed to neighboring countries. He also showed that rufous lilies appeared 19 to 18 million years ago. However, it only underwent explosive speciation in Meghalaya and Indo-Burma around 3–2 million years ago. This period, where several different species of Rufous Lily evolved over a short period of time, coincides with the intensification of the Himalayan uplift.

The multi-stage uplifts of the massive Himalayan mountain range began to form 50-40 million years ago when the Indian tectonic plate collided with the Eurasian plate and continued to sink into it. The collision and uplift resulted in significant climatic changes and new geophysical environments. This resulted in the onset of the monsoon system in Asia and the seasonality of rainfall. However, the monsoon strengthened 15 to 4 million years ago.

When a species diversifies over a short period of time compared to its long uneventful evolution, many branches are considered a group in the phylogenetic tree.

“We can observe that many new species have appeared at a time that corresponds to the intensification of the Himalayan uplift,” explains Dr. Ajith Ashokan, the first author of the article.

In a given environment, the functional role of an organism in an ecosystem is called a niche. For example, the niche of fungi is to decompose dead matter. Dr Vinita Gowda, leader of the current research team, says: “The uplift of the Himalayas has resulted in the creation of new environments. These environments, in turn, created and opened up more ecological niches which forced species to adapt to these new environments, evolving into different species.

The Himalayas have also formed physical barriers isolating populations. Isolated populations can evolve into different species. Additionally, the Eastern Himalayas have a high diversity of Rufous Lilies as many species have arrived from the nearby Indo-Burmese region.

The origin of the monsoons may also have played an important role in the diversification of these plants.

“Rux lilies love moisture and are found in the humid tropics of India and Asia. As the Asian monsoon intensified, there were more days with high humidity for these plants are thriving and spreading. This has probably also helped them to diversify rapidly in northeast India,” says Dr Gowda.

The eastern Himalayas experience more rainfall (average annual rainfall 3,800–4,000 mm), while the western Himalayas are much drier with an average annual rainfall of 75–150 mm. This difference in rainfall may have caused the Rufous Lilies to evolve into different species to populate these very different habitats.

The presence of semi-arid regions in central and northern India due to land drying over time acted as barriers to the spread of Indo-Burma and Himalayan species to the south of peninsular India. As a result, we only find about six species of Rufous Lily in the Western Ghats.

Malay Archipelago ginger lilies are epiphytes (plants growing on other trees) and have a short stature. The researchers found that this epiphytic trait and small size may have been traits first seen in the ancestral Ginger Lilies millions of years ago. These characters may have evolved to avoid being overwhelmed by the ground when sea level fluctuations cause flooding. Growing on a tree allows ginger to avoid death when the ground is submerged.

Thus, the current diversity of rufous lilies results from many geographical and climatic factors such as the uplift of the Himalayas, the monsoon, the aridification and the evolution of the sea level. These have played an important role in the diversity and distribution of the Ginger Lily we see today. The researchers highlight the importance of studying plant diversity globally to understand current diversity. This study led by Dr. Gowda is a collaborative effort with botanical gardens and natural history museums in different countries. Much like the present study, the evolutionary and biogeographical history of an organism must be constructed not only on an expansive geographic scale spanning many countries, but also on a geological time scale to understand the full story.

Currently, the highly diverse forest regions of Indo-Burma and Borneo are threatened by deforestation. These regions are the diversity hotspots of the Rufous Lily and many other species. Commenting on the implications of this study, Dr Gowda says: “From a conservation perspective, the effect of rapid climate change as well as habitat loss in the northeastern region (of India) may be prove fatal to gingers and many other plants. species we study. If some species in certain regions of their distribution become extinct due to human-made reasons, such as urbanization and plantations, we are missing crucial puzzles in the full evolutionary story of that particular group.

This article has been reviewed by the researchers, whose work is covered, to ensure accuracy.

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