Why the list of bird species in the world does not match

Chamian pitta was recently split as a different species from the Rufous antpit. Credit: Çağan H.Şekercioğlu

How many kinds of birds are there in the world? It depends on who you go through. The number can range from 10,000 to 18,000. The list of species is difficult to standardize because the concept of “species” itself is a bit vague.

This is important because in order to conserve biodiversity, we need to know what kind of diversity exists in the first place. So a biologist, led by Montenit Craig, a candidate for a doctoral program at the University of Utah, compared four major lists of birds around the world to find out what the differences were and why. .. They agree that the list agrees with most birds, but finds that discrepancies in some parts of the world can mean that some species have been overlooked by conservation ecologists. did.

“Seeds are more than just names,” says Neate-Clegg. “They are the functional units of a complex ecosystem that need to be preserved. We need to recognize the true diversity to preserve it.”

The results are published in Global ecology and biogeography..

About the origin of the species

The definition of the species is not clear. Some scientists define populations as different species if the populations are reproductively isolated from each other and cannot be mated. Others use physical features to describe the species, while others use genetics. Using the genetic definition, more species are produced, but the gray area persists regardless of the method.

“The seed is fuzzy because the speciation as a process is fuzzy,” says Neate-Clegg. “It’s a step-by-step process, so it’s very difficult to draw a line and say,” This is two species “and” This is one species. ” “

He also says that physical and genetic features do not always diverge on the same timescale. “For example, a population of two birds can differ in song and appearance before genetic divergence. Conversely, the same population on different islands can be genetically separated by millions of years. There is sex. “

List comparison

At this point in the story, here are four lists. Each list is intended to include all bird species from around the world. they are:

“Being an active bird scholar who is always trying to identify bird species means that we are always faced with the problem that one species is on one list and not on the other.” Çağan Şekercioğlu, an associate professor of the Faculty of Biological Sciences, said. “So our field experience was very inspiring to think about this question and inspire us to write this treatise.”

The list has different strengths depending on the application. For example, BirdLife International’s list is integrated with the IUCN Red List, which reports on species conservation status. The IOC list is updated by experts twice a year, says Şekercioğlu. This list is open access compared to other major lists and changes are transparently documented.

“But as a birdwatcher, I always use eBird. It uses the Clements checklist and its dataset is very powerful in itself,” says Neate-Clegg. “Therefore, there is no single best option.”

An example of a discrepancy between lists might be a common bird Hashibosokitsuki.. On the eBird list, this is called the Northern Flicker. However, BirdLife International’s list describes the eastern population as flickering on the yellow axis and the western population as flickering on the red axis.

In 2020, Neate-Clegg and his colleagues read a study comparing birds of prey on each list and found that only 68% of the species were consistent on all four lists.

“I found it interesting to investigate the taxonomic concordance of all 11,000 species of birds,” says Neate-Clegg. “More importantly, I wanted to find out which species of trait caused more or less taxonomic confusion.”

They collect the latest versions of each list (IOC checklists are updated semi-annually, researchers update annually, Clements and Birdlife lists update annually, but Howard and Moore update since 2014. (Not done), I started by truncating them to rule out variants. Extinct species. Using some other data processing rules, I assigned a single name to all possible species in all four lists. Then the comparison started.

If the list agrees and disagrees

Researchers found that the four lists agreed with the majority of birds (89.5%). Then, for the remaining 10.5%, they began looking for patterns that could explain the discrepancy. Some of it was probably geographical. Birds from the well-studied Northern Hemisphere were more likely to find consensus than birds from the relatively unstudied Southeast Asia and the Antarctic Ocean.

Some of them were habitat-based. Larger migratory species in relatively open habitats had a higher concordance rate.

“I think the most surprising result was that the consensus on forest-dependent species wasn’t low,” says Neate-Clegg. “These inhabitants of the rainforest floor predicted that taxonomic relationships would be more uncertain, the most mysterious and difficult to study, but in reality, moderate forests have low taxonomic consensus. It turns out to be addictive species. We believe these species will move. Just enough to diverge, but not as much as their gene pools are constantly mixed. “

Also, some of the problems with species classification on isolated islands such as Southeast Asia and the Antarctic Ocean were a phenomenon called “mysterious diversification.” Although the islands are isolated and can promote species diversification, the two populations on different islands are very similar, even though they suggest that the genes have been isolated from each other for millions of years. It may appear to be. Therefore, by definition, two populations can be counted as two species or only one.

“Furthermore, if geographically separated, we do not know if the two populations can cross to produce fertile young individuals, so we test the concept of traditional species in the island’s fauna. That’s very difficult, “says Neate-Clegg.

Important reason

But what if some people disagree with the species designation? Conservation activities are usually done at the species level, says Neate-Clegg.

“If an island population goes extinct, people may not care too much if it’s just a subspecies,” he says. “Still, the island can lose a functionally unique population. If it was recognized as a complete species, it might not have been lost.”

Neate-Clegg hopes that this study will direct ornithologists to a group of species that deserve more attention.

“We also want conservation biologists to be aware that mysterious diversity may be overlooked, and we need to consider conservation units above and below the species level,” he adds. It was.

Community science birdwatching data has not yet captured global bird trends

For more information:
Montague HC Neate-Clegg et al, Ecological and biogeographic predictors of taxonomic inconsistencies across the world’s birds, Global ecology and biogeography (2021). DOI: 10.1111 / geb.13300

Provided by the University of Utah

Quote: The reason why the list of bird species in the world does not match (April 7, 2021) is from https: // April 7, 2021 Obtained on the day

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Why the list of bird species in the world does not match

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