Years of global observations of biodiversity have revealed underlying consistent patterns that indicate how many species are common, very rare, and how many are somewhere in between. Ta.
More than a century of observations of nature have revealed consistent patterns in the world. seed Abundance: Most species are rare, but not extremely rare, with only a handful being very common. These so-called global species abundance distributions are now fully defined for some well-monitored species groups, such as birds.
However, for other species groups, such as insects, the veil remains partially lifted. These are the findings of an international team of researchers led by the German Center for Integrated Biodiversity Research (iDiv), Martin Luther University Halle-Wittenberg (MLU), and the University of Florida (UF), and published in the journal Nature. natural ecology and evolution. This study shows how important biodiversity monitoring is for detecting the abundance of species on Earth and understanding how they change.
“Who can explain why some species are widespread and extremely abundant, while other closely related species are narrow and rare?” This question was first published over 150 years ago. It was proposed by Charles Darwin in his landmark book On the Origin of Species. A related challenge was to understand how many species are common (abundant) and how many are rare, the so-called global species abundance distribution (gSAD).
Two major gSAD models have been proposed in the last century. The statistician and biologist RA Fisher proposed that most species are very rare and that the more common species decrease in number (the so-called log-series model). On the other hand, engineer and ecologist F.W. Preston argued that only a small number of species are actually very rare, and that most species have some moderate degree of commonality (the so-called lognormal model). But until now, scientists didn’t know which model explained Earth’s true gSAD, despite decades of research.
Solving this problem will require a huge amount of data. The study authors used data from the Global Biodiversity Information Facility (GBIF) to download data representing his observations of more than 1 billion species in nature from 1900 to 2019.
“The GBIF database is a great resource for all kinds of biodiversity-related research, especially because it brings together data collected from both professional and lay scientists around the world.” said lead author Dr. Corey Callahan. He started his studies while working at his iDiv and his MLU and now he works at UF.
Callahan and his fellow researchers divided the downloaded data into 39 species groups, including birds, insects, and mammals. For each, they compiled a respective global species abundance distribution (gSAD).
The researchers detected a potentially universal pattern that emerges once the distribution of species abundance is fully clarified. As predicted by the log-normal model, most species are rare but not extremely rare, and only a small number of species are very common. But the researchers also found that only a small group of species, such as cycads and birds, have completely lifted the veil. Data are still insufficient for all other species groups.
“In the absence of sufficient data, most species appear to be very rare,” says senior author Professor Enrique Pereira, research group head at iDiv and MLU. “But when you add more observations, the picture changes. You start to see that there are actually more rare species than very rare species. Comparing our observations with today’s more comprehensive species observations shows this change in cycads and birds. It’s interesting that, as predicted by Preston decades ago, the existence of a complete species Only now can we clearly see that the phenomenon of revealing quantity distributions has been demonstrated on a global scale.”
“We’ve been recording observations for decades, but only a few groups have been uncovered,” Callahan says. “We still have a long way to go. But GBIF and data sharing truly represent the future of biodiversity research and monitoring for me.”
The results of the new study allow scientists to assess how well gSAD is understood for different species groups. This answers another long-standing research question: How many species are there? The study found that in some groups, such as birds, nearly all species have been identified, but not in other taxa, such as insects and insects. cephalopod.
The researchers believe their findings may help answer Darwin’s question about why some species are rare and others common. The universal patterns they found may indicate common ecological or evolutionary mechanisms governing species commonality and rarity.
While more research is being done, humans continue to modify the planet’s surface and species richness, for example by making common species less common. This complicates researchers’ tasks. They need to understand not only how species richness evolves naturally, but also how human influences simultaneously change these patterns. We may still have a long way to go before Darwin’s questions are finally answered.
Reference: Corey T. Callahan, Luis Borda de Agua, Roel van Klinck, Roberto Lozzi, and Enrique M. Pereira, “Unraveling global species abundance distributions,” September 4, 2023 Day, natural ecology and evolution.
DOI: 10.1038/s41559-023-02173-y