Bananas are in trouble:
By all measures, the banana is already a terminal patient. It’s a highly inbred clone, it hasn’t reproduced sexually in centuries–all plants are grown from cuttings, it has no seeds from which to grow new fertile plants or make natural hybrids via pollination, no one bothered to keep a fertile healthy strain in reserve should future problems arise, and it’s so prone to environmental hazards that commercial operations bathe the plants in anti-fungals and pesticides in unprecidented levels.
Read more at BorderWars.
Oh. Haven’t eaten bananas for a decade or mo’. Now when you mention this, I recall haven’t seen them on the stores either. Well leave’em for the monkeys, the wild ones.
If it “hasn’t reproduced sexually in centuries” how does that fit the definition of “inbred”, which is defined as the mating of close relatives?
“Clones” are reproductions of the original (or “parent”) stock. Not to say that clones don’t have their own problems…
I would have used a different term. They are actually more like the guppies that reproduce through parthenogenesis and are poorly fit for life in parasite ridden pools.
How the plant is cultivated (cloned via offsets) is a distinct issue of how the genetics were set in the first place.
The creation of the strain was the result of excessive inbreeding and a genetic trick (much like creating a mule and then mating it to your horse to produce a sterile donkey).
Triploid guppies are an appropriate analog, though, as offset clones and parthenogenesis produce the same results (seedless bananas are also triploid).
There are two things true about Bananas, the first more significant than the second.
1) Banana plant clones are all essentially the same genetically, so a disease strain that can attack one plant can attack all the plants in the crop.
2) Banana plants have lowered fitness due to a greater frequency of homozygous deleterious recessive alleles.
These are separate and unequal issues in the case of the banana.
Are you talking about dog breeds or bananas?
The issues are very similar.
Just talking bananas in response to M.R.S.’s concern that “hasn’t produced sexually in centuries” and “inbred” are mutually exclusive.
They actually have nothing functionally to do with each other in this case.
For example, you can asexually reproduce many plants and this in no way alters their hetero/homo-zygosity.
The important thing about this strain of banana is that it’s *only* reproduced asexually meaning that we can no longer recombine the genetics the easy old fashioned way.
It will either require in-lab gene splicing, or in-lab un-doing of the forced triploidy. Although, even if we can undo that, it’s not like we have much of any diversity to breed to anyway. They were inbred before hand.
http://www.genomenewsnetwork.org/articles/07_01/Banana_genome.shtml
They are both inbred and clones. Those terms are not mutually exclusive. “Inbred” or homozygosity, the real issue, persists in a clone. And if you read my “Inbreeding is Screwing Yourself” post, you’ll see just how fast (and how far) you can inbreed a plant that can self pollinate.
A clone of a heterozygous plant would not be any more inbred or suffer any more problems than the plant itself. Whereas inbreeding approximates cloning, given that you remove and duplicate so much information as to only pass along that information, cloning is not in any way dependent on inbreeding.
A clone actually allows you to escape the time restriction (be it generations or years) that you imply matters.
The banana you eat today is genetically identical to the one grown 100 years ago the last time that strain mixed genes.