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How do scientists estimate the number of species on Earth? Reveal the surprising findings of the latest research!
The Earth's biodiversity not only reflects the diversity of life, but is also the basis for human survival on this planet. However, with changes in ecosystems and the impact of human activities on the environment, there is still great uncertainty in researchers' estimates of how many species there are currently on Earth. According to the latest research, scientists estimate the number of species on Earth to be between two million and one billion, but the benchmark for most studies is still around 11 million.
"More than 80% of species have yet to be described, which means our understanding of life on Earth is still very limited."
As of 2018, approximately 1.74 million species have been registered in the world, but this is just the tip of the iceberg. As you can imagine, these numbers will continue to change as new species are discovered.
In some studies, the number of living species is thought to be around 1.9 million, but some scientists estimate that 20% of these names are synonyms, so it is not so much that Rather, there are about 1.5 million validly described species. A 2013 study published in the journal Science estimated that there are between five and eight million living species on Earth, although this number has sparked some controversy. In addition, another study published in PLoS Biology in 2011 predicted that there are about 8.7 million eukaryotic species on Earth, but this number also varies within 1.3 million.
"The DNA of the entire Earth corresponds to about 5.0 x 10^37, which is almost unexpectedly large."
The total number of species on Earth is not only an indicator of the diversity of life; it is also influenced by extinction and speciation. Background extinction rates vary among taxa but occur at approximately one extinction per million species-years. Mammals, for example, typically live about a million years. In Earth's past, biodiversity has increased or decreased due to a number of abiotic factors, one of which is climate change. Climate change 299 million years ago led to the collapse of tropical rainforests and a subsequent loss of diversity, with amphibians being particularly affected.
Currently known species
According to Chapman, data summarized in 2005 and 2009 indicate that there are approximately 1.9 million described species, but the total number is likely to be between 11 and 12 million ( including described and undescribed species). For fossil species, accurate numbers are harder to come by; although around 250,000 valid fossil species have been described, this is still considered a tiny fraction of all species that have ever lived.
"Currently, about 18,000 to 19,000 living species are described each year, which shows that our understanding of biology is gradually deepening."
In the development and advancement of biodiversity indicators, several indicators have emerged to describe global biodiversity trends. While there is no single indicator for all living species, the Living Planet Index (LPI) is a population-based indicator that uses data from many vertebrate populations to create an overall index. By 2012, the Global Living Planet Index had fallen by 28%.
Another indicator, the Red List Index, is based on the International Union for Conservation of Nature's Red List and is used to measure trends in species conservation status over time. It currently includes the following groups: mammals, birds, amphibians and corals. However, challenges faced by these indicators are also evident due to data availability challenges, including taxonomic gaps and the age of each index.
"The loss of biodiversity is a global challenge that requires the joint efforts of each of us to protect it."
Faced with such a huge amount of data and trends, can we successfully find undescribed species in the future and take practical measures to protect biodiversity?
