The tree of life of flowering plants, like our family tree, helps us understand how different species are related to each other. The tree of life, like the molecular fossil record, is discovered by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time. Thanks to advances in DNA sequencing technology, our understanding of the tree of life is rapidly improving.
Recently, scientists from the Royal Botanical Gardens, Kew, together with colleagues from the Kunming Institute of Botany (KIB) of the Chinese Academy of Sciences and the surrounding area, have created a large DNA tree of life, providing open access to more than 100 DNA sequences. 9,500 flowering plants. This invaluable resource gives us answers to fundamental questions about modern plant life and offers a glimpse into the past and its origins. Their research was recently published Nature.
Technological advancement in DNA sequencing
An important advantage of the approach is that it can be used to sequence a wide range of plant material, old and new, even if the DNA is severely damaged. The vast treasures of dried plant material in the world’s herbarium collections, containing approximately 400 million scientific plant specimens, can now be examined genetically.
Using such samples, the researchers sequenced a sandstone sample (Arenaria globiflora) was collected in Nepal almost 200 years ago and, despite the poor quality of its DNA, managed to place it on the tree of life. They even analyzed extinct plants such as the olive from the island of Guadalupe (Hesperelaea palmeriPerson who has not been seen alive since 1875. In fact, 511 of the species listed are currently in danger of extinction, according to the International Union for Conservation of Nature. The list, including three more, looks like this: hesperelaeaThey are already extinct.
Global collaboration and new discoveries
More than 3,400 of the 9,506 species sequenced for this study were obtained from material from 163 herbaria in 48 countries and additional material from plant collections worldwide (e.g., DNA banks, seeds, and living collections).
Among the species sequenced, the DNA of more than 800 had never been sequenced before. This sequence was important in filling important knowledge gaps and shedding new light on the evolutionary history of flowering plants. The researchers also highlighted the value of an open science approach for future genome research, using publicly available data on more than 1,900 species.
Despite the contrasting biological properties of nuclear and plastid genomes (e.g., size, copy number, mode of inheritance, recombination, and rate of evolution) that can lead to conflicting phylogenetic trees, the results largely support a phylogenetic classification based primarily on plastids. Phylogeny group IV of angiosperms. For example, 58 of the 64 currently accepted orders and 406 of 416 families have been recovered as monophyletic (excluding works).
The most striking exception is the nemophilia of Asters, the largest angiosperm family that includes sunflowers and their relatives. The tree obtained from this study also confirms 85% of the relationships between families reconstructed by KIB scientists using the plastome-based angiosperm phylogenomic tree.
Darwin’s “vile secret” and his ideas of evolution
Flowering plants appeared more than 140 million years ago and then quickly replaced other vascular plants. Darwin was astonished by the sudden appearance of such diversity in the fossil record and wrote: “So far as we can judge, the rapid development of all higher plants in the last geological ages is a terrible mystery.”
Using 200 fossils, researchers traced trees of life back into the past to show how flowering plants evolved over geological time. They found that early-flowering plants actually exploded in diversity, just as Darwin noted. The rapid development of these plants gave rise, shortly after their emergence, to over 80% of the main lines that exist today. However, this trend declined to a more stable rate over the next 100 million years; until another burst of diversification occurred about 40 million years ago, coinciding with a drop in global temperature.
These new discoveries would fascinate Darwin and would undoubtedly be helpful to today’s scientists grappling with the challenges of understanding how and why species diversify.
The flowering plant tree of life has tremendous potential for biodiversity research. Because just as you can predict the properties of an element based on its position in the periodic table, the position of a species in the tree of life allows you to predict its properties. Therefore, new data will be of invaluable value not only for the development of many branches of science.
To make this possible, the tree and all its underlying data have been made openly and freely available to both the public and the scientific community, including the Kew Tree of Life Explorer. Researchers believe this type of open access is key to democratizing access to scientific data worldwide.
Open access will also help scientists make the most of data; for example, it will combine data with artificial intelligence to predict which plant species may contain molecules with medicinal potential. Likewise, the tree of life can be used to better understand and predict how pests and diseases will affect plants in the future. Ultimately, the use of this data will depend on the creativity of the scientists who have access to it, the researchers say.
Source: Port Altele
