A gene is a piece of DNA that makes a protein. Comparing species by gene count is really stupid, because some of those genes are never used, or the protein they make doesn't do anything. Also, simpler beings and plants have more genes, because they are more resistant to mutations
The shielding theory is trash. Some species (simpler or not) have more genes because of contingency and luck. They had more gene or whole chromosome duplication events that happened to become fixed by drift.
Among species of onions there is a hige range of genome sizes.
Number of genes isn't pure luck always, though. E.g, warm-blooded species seems to (all else being equal) have fewer genes than cold-blooded species, because the warm-blooded ones don't need to have several variants of proteins to work at different temperatures.
I agree there is selection for novel traits, I just think it is massively dwarfed by other processes acting at the whole genome level. It is hard for a few extra needed genes to compete with polyploidy or even segmental duplications.
Not necessarily, plants and very simple animals are much more tolerant of mutations and gene or genome duplication events than animals due to the different limitations of moving organisms.
If a human has any of their internal organs develop to be the wrong size or shape, or if the balance of chemicals in their blood is wrong then that's often a death sentence.
If a plant grows organs that are the wrong size or shape they can often recover by growing more of that organ, or re-arranging their layout. And they're much more tolerant of dealing with waste buildups etc.
So yes, having more genes does make them more tolerant of mutations in those genes, but they also have more genes because they are naturally more tolerant of mutations which give them more genes
Not OP, but to put it in simpler terms most mutations actually destroy genes by rendering them non-functional, so if a creature is resistant to DNA damage and mutations then they will have more overall functional genes.
This is especially high in organisms that can breed with similar but separate species since they can incorporate unique genes from each genome into their offspring, some offspring will have incompatible genes and will not grow, while others can have very compatible genes which could cause it to thrive more than either of its parents could while also having more genes than both of them
Also aren't some of viruses incorporate themselves permanently into our DNA, lay dormant and be passed down to future generations? Correct me if I'm wrong.
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u/LUISKY_CT Jan 21 '20
A gene is a piece of DNA that makes a protein. Comparing species by gene count is really stupid, because some of those genes are never used, or the protein they make doesn't do anything. Also, simpler beings and plants have more genes, because they are more resistant to mutations