Is there any reason why propagation method may effect the amount of deleterious alleles in crop species

[Dean22April]

Hey! 

I have just been reading some research papers and not sure if this is a defined trend yet, but I've noticed some crop types (e.g. vegetativley propagated) have a higher proportion of deleterious mutations compared to their wild progenitors than other crop types (sexually produced cereals) depending on method of propagation. I was wondering why this may be? Or is this just a fluke?

Examples: 

1. Clonally reproduced: Grapes have 5.2% more deleterious mutations than its wild ancestor (Zhou et al., 2017 Proceedings of the National Academy of Sciences, 114(44), 11715-11720)
2. Clonally reproduced: Cassava has 26% more deleterious alleles than its wild ancestor (Ramu et al., 2017 Nature genetics, 49(6), 959)
3. Sexually reproduced: Rice has 3-4% more deleterious mutations than its wild ancestor (Liu et al., 2017 Mol Biol Evol 34:908–924)

Any help would be hugely appreciated 

[StringJunky]

35 minutes ago, Dean22April said:

Hey! 

I have just been reading some research papers and not sure if this is a defined trend yet, but I've noticed some crop types (e.g. vegetativley propagated) have a higher proportion of deleterious mutations compared to their wild progenitors than other crop types (sexually produced cereals) depending on method of propagation. I was wondering why this may be? Or is this just a fluke?

Examples: 

1. Clonally reproduced: Grapes have 5.2% more deleterious mutations than its wild ancestor (Zhou et al., 2017 Proceedings of the National Academy of Sciences, 114(44), 11715-11720)
2. Clonally reproduced: Cassava has 26% more deleterious alleles than its wild ancestor (Ramu et al., 2017 Nature genetics, 49(6), 959)
3. Sexually reproduced: Rice has 3-4% more deleterious mutations than its wild ancestor (Liu et al., 2017 Mol Biol Evol 34:908–924)

Any help would be hugely appreciated 

I'm only a layman but: as organisms get older, the fidelity of replications goes down and the probability of mutations increases anyway. Cloned offspring are the same age as their parents and carry the same state of senescence as the parents. The act of cloning adds its own stresses, producing even more mutations. Sexual reproduction resets the clock, so to speak, and any flaws in the offspring  genes will also, with greater likelihood, be cancelled out at fertilisation.

Edited March 5, 2018 by StringJunky