Whereas the hyperlink between avian species and chemistry may appear spurious – perhaps one thing coming from a chemist who desires to show that “chemistry is every part” – it’s really fairly clear-cut and powerful.
Birds are of the identical species if their genetic info could be very related, and never of the identical species if it’s not. And the genetic info of birds (and different animals) is encoded of their DNA, which is a chemical molecule.
Or to quote the Nationwide Human Genome Analysis Institute, “Deoxyribonucleic acid (DNA) is a molecule that accommodates the organic directions that make every species distinctive”.
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DNA consists of two strands (chains) of polynucleotides. The “poly” implies that every strand consists of a lot of nucleotides. And every nucleotide in itself has the same (however not an identical) construction – it accommodates a sugar, a phosphate group, and one among 4 nitrogen-containing nucleobases. The best way the genetic info is saved within the DNA is within the sequence of the 4 potential nucleotides within the general chain.
What info is it that’s saved within the avian DNA? Data on
- The form of beaks, wings, and feathers
- The colour of feathers
- Habits, corresponding to some calls and migratory habits
- Physiology, such because the metabolism or the immune system
However isn’t the DNA between two completely different people – or birds of the identical species – additionally completely different? True – however the variations are very small. So, provided that the distinction in DNA exceeds a sure threshold does it make sense to talk of various species.
As a tough rule, the distinction in a selected area of the DNA (the mitochondrial COI gene, which is usually used for DNA barcoding in birds) must be 2-3% or larger to separate completely different species. If the distinction is smaller, hybridization should be potential.
And what does that imply when it comes to a timeline? How lengthy does it take for 2 chicken populations beginning with an identical DNA to develop a distinction of 2-3%?
A tough estimate provides a price of 1 to five million years. That is primarily based on the truth that the DNA of a species mutates at a comparatively fixed fee of 1% per million years. So, if our two populations are separated and mutate at this fee, after 1 million years, their DNA differs by about 2% (as every has moved away by 1% from the start line). To succeed in a divergence of three%, it would take about 1.5 million years. As some mutation charges are decrease, even longer occasions as much as the 5 million years talked about above are potential.
So, if the chemical substances that characterize two particular person birds – their DNA – are completely different sufficient, they’re of various species. And if there’s a distinction, however it’s not very huge – say, someplace between 0.1 and 1% however effectively beneath 2% – this may occasionally point out subspecies of the identical full species.
Illustrations:
“DNA – Blue” by Spanish Flea is licensed below CC BY-NC-ND 2.0.
By File:Distinction DNA RNA-DE.svg: Sponk / *translation: Sponk – Chemical buildings of nucleobases by Roland1952, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9810855
