Monday 28 October 2019

Hybridisation is more important in evolution than we have been led to believe

How things began (for me)

I remember how I avidly devoured a series of school programmes called ‘How things began’. I want to say pre-school but on reflection it might have been in the school holidays. (On further reflection school programmes did not go out in the holidays - the timing is not a false memory).
I started a lifetime of intense interest in evolution - although  actually it was never even mentioned at school

I only formally learnt about evolution for A level biology at Hartlepool Technical college (N.E. grammar schools did not deign to teach things biological). I remember an early essay about evolution when addressing the concept of animals appearing as from nowhere in the fossil record and often remaining for millions of years almost unchanged before becoming extinct or still surviving.
I remember mentioning hybridisation as an explanation for this phenomenon of apparent sudden appearance in the fossil record. Metaphorically my suggestion had a thick red line drawn through it.
I know the conventional explanations but in truth evolutionists have always blurred hybridity over.

Nowhere in the school version of evolution did hybridisation appear. Everything was in a straight line and nature’s new innovations were never shared.
Schools still teach that rag bag of horse ancestors as if one came directly from one another whereas in truth in evolutionary terms they are not even in the right order.  If you regarded them as close relatives which sometimes got together you would be nearer the truth. (Impossible with the actual examples that are distant in time and distinct in genome). The arrow of our much beloved genetic trees would seem to be broadly true but much more meandering than generally portrayed.

Albenga and Shirley are F1 hybrids
My next foray into hybridisation was at Wye College when in a student exercise in public speaking I had to give a talk to classmates on a research paper called ‘heterosis versus variety’ in relation to breeding tomatoes. It is etched on to my mind
Heterosis is the posh word for hybrid vigour and is associated with bringing together of two inbred genetically uniform distinct parents (albeit actually close in genetic distance) where off-spring tend to be uniform heterozygotes and lacking in often inferior paired recessive genes. (don’t ask).
It requires the cross to be repeated for each new generation of seeds which suits seedsman very well.
I subsequently learned that all the advances of bringing distinct genes together can in much more expensive longer breeding programmes be stabilised in true breeding varieties.
I would imagine advantages of hybrid vigour become stabilised in evolutionary processes too

Influence of Agriculture and Horticulture

''Pink Panda' is a cross between a strawberry and a cinquefoil 
Perhaps in the popular mind creation of horticultural hybrids bare no resemblance to the process of evolution. The elementary text books would have it that way and indeed any hybrids are an inconvenient aberration.

We gardeners and farmers meet hybridised plants and animals every day and just about all the plants we grow in our gardens are hybrids. I don’t mean immediate hybrids between distinct genera and species although there are thousands of those too. Just between varieties and closely related forms. They all have numerous hybridisation events in their long ancestry, some more distant genetically but most more closely related. Just think of promiscuous aquilegia species that cross and seed themselves everywhere.

Christmas cacti  hybrids thrive in the jungle
In the popular mind hybrids are some kind of aberration. In truth they are an integral part of evolution and a means that diversity is created and shared.
It is almost universally excepted knowledge among professional botanists that half of the world’s plants are hybrids. I suppose they mean theorised from known or mooted hybridisation events over the past few thousand years. Go back through evolutionary time I believe all have been influenced by hybridisation on many occasions.

A popular illusions about hybridisation
It is less relevant to animals

 A mule is a hybrid between a horse and a donkey, A chance of  being fertile is about a million to one. Inevitably mules have been born to donkey or horse fathers
Certainly for want of a compatible partner animal hybrids have less chance to breed. The more distant the cross the less fertile a hybrid will be and such as the mule are said to be sterile (on the net you will find opposite claims). 

Primula kewensis arose as a hybrid between two species of primula and the flowers remained sterile for years before fertility arose
Plants that can propagate vegetatively can sit around longer to find a compatible mate or fertility to arise

As already mentioned most hybridisation events  are between fairly close  relatives and a substantial number are fertile.
Even rare extremely distant crosses where the odds against fertility are thousands, even millions to one might have the chance to procreate. Such odds are as nothing over evolutionary time

The most likely partner of a new hybrid is one of the parent species. If in rare events the progeny of a first or early cross are geographically isolated or in some other way physically separated they might start new evolutionary lines. New species can start this way. In fact some people think almost all new species start this way.

A new hybrid’s most likely fate is that they are subsumed into one of the parent lines as succeeding generations mate. Even though such hybrids are ‘lost’, genes have crossed over from species to species and if some are advantageous will potentially be repeatedly passed on as 'near' species mate. (A to B to C.... ad infinitum)

Thrum and pin eyed flowers which aid cross-pollination are found in a large range of very diverse families
This process is known as introgression and I believe it to be very significant. Not only significant, but in terms of millions of potential liaisons universal and common.

Hybridisation news
I try in my posts on hybridisation to report new developments as the world starts to embrace hybridisation’s evolutionary significance. The new atmosphere is well illustrated by a post on the BBC website which inspires two of the three items I mention today

1. New hybrid coral

Acropora prolifera (dig that name) is a natural hybrid that has been discovered on the sea walls in the vicinity of Miami harbour and thrives there but unfortunately is threatened where colonies are inundated with silt.
Although it is sterile this is no barrier to distribution as corals propagate vegetatively. Efforts are being made to establish it out at sea and develop efficient  propagation techniques. It is a classical example of where an environment is inhospitable to parent species - virtually all have died out - and without their competition the new hybrid can thrive. In this case being sterile there are not even backcrosses involved

2. Human ancestry

Recent discoveries of hybridisation’s major influence are being further entrenched in public acceptance by articles such as the BBC piece linked below. It provides many interesting links to recent research.
The program which mainly reports on recent discoveries does touch upon very early human ancestry millions of years ago (most evidence that can be gleaned from genetic analysis is relatively recent - perhaps a maximum of half a million years or so. The further back you go it becomes much harder to hypothesise where genes have come from).
It does puzzle me why our ‘recognised’ very early primate ancestors would have had such very long periods of stasis as suggested by the fossil record.
After all hybridisation is not new and has been happening since the dawn of sex in multi-celled organisms.

3. Docile killer bees

Thank you New Scientist for your story ‘chiller bees’
You will have heard stories about South American hybrid killer bees that are dangerously aggressive. You might have even seen films - both real and fictional stories of their aggressive ways.
It’s broadly true.
The original hybridisation was by a Brazilian bee keeper in the mid nineteen fifties He brought aggressive African bees from Tanzania in an attempt to strengthen the weakening populations of Brazil’s own domesticated european bees. Unfortunately the hybrids escaped and bred further with South America's own wild populations. Now they are found throughout and beyond South America. They are very aggressive indeed and are the sort of thing that get hybrids a bad name.
There the story might end except the hybrid bees arrived in Puerto Rica; it’s more densely populated than most other places and for bees has a hostile climate where natural selection is extremely acute. Within a decade or so extremely docile swarms started to appear. Even better they were prolific producers of honey and healthy. They are thought to have huge potential through further hybridisation to improve world bee populations. This time with necessary safeguards.
The genetics are very interesting. Apart from hybridising creating new gene combinations, what happened in Puerto Rica illustrates very rapid evolution by natural selection.
Where past hybridisation gives nature variation to work on, relatively small but significant changes can be very speedy.

The most convincing explanation is that the wild  bees  descended on this very heavily populated island where selection pressures were huge as the bees were so feared and mercilessly hunted. Only quiet ones survived to produce fertile queens.

Hybridisation is not the only means that genes cross over

The monarch butterfly contains genes from a spider
It is called horizontal transfer, where genes have wandered from the the much vaunted traditional ‘straight line’ from the first ancestor. Hybridisation and attendant introgression are the obvious cases but in primitive ‘pre-sexual’ organisms swopping genes such as antibiotic resistance is far too common.

A recent New Scientist carried details of natural transgenic plants. It claims that at least 5% of the world’s plants carry transgenic genes that have been transferred by the bacteria agrobacterium. (It does this for its own nefarious purposes and the means is fundamental to the development of CRISPR that we will not discuss here)

It is ironic that this research comes from St Petersburg university. As I observed in an earlier post on hybridisation the Russians were past masters in utilising hybridisation in early plant breeding. That’s before their pioneering genetics research was trashed for half a century by Lysenko.
The recent Russian research suggest that bacterial transfer might be a route to the development of new species.
The New Scientist article also refers to gene transfer by virus.

I was astonished at the statement in the same article that the intimate cell connections induced in plants by common grafting has been transferring genes for millennia.
That goes against everything I have been taught in my lifetime.

I am yet to be persuaded.
Interesting that the Russians claimed transfer of  information by grafting more than a century ago


The recent article on the BBC website

My 2015 article on hybridisation which refers to Vavilov the great Russian geneticist.

I have written eight articles on hybridisation linked in the theme column

Monday 14 October 2019

Getting rid of Japanese knotweed quickly and cheaply(?)

The most expensive plant in your garden
Everything is relative. A year would be ‘quickly’. As to ‘cheaply’ I mean compared to a second mortgage to pay a contractor to eliminate JKW (I will call it) before you can sell your house.

It is in the news again relative to invaded railway properties and creeping into adjacent gardens.
Of course it is over-hyped. Worse plant dangers can threaten your home. Think of trees near your house when you have a clay soil. Things like brambles and bamboo if left for years can be a real problem.
They just do not get the publicity to be cast as evil alien invaders.

It is a perfect storm. A whole industry exists to extract huge payments to eliminate it. In unconscious cahoots with surveyors who believe the hype and who consider homes are seriously threatened. (They are when house agents put the fear of god into clients - both sellers and buyers)

It is not that that JKW is inconsequential. It’s just that with a little forward planning by homeowners a year or two in advance of selling they can easily eliminate it with glyphosate. Good gardeners will not have it all.

Here again another perfect storm creates a problem. Apart from irrational fears of glyphosate safety being high in the public domain, pesticide regulations get in the way of law abiding citizens who are led to believe that using professional glyphosate is illegal. There is a kind of conspiracy that keeps amateur gardeners and professionals apart. And certainly there are good reasons that the general public should not use particular chemicals.
Professional suppliers do not want to bother themselves with amateur’s foibles and very small purchases. The likes of garden centres want to trade in products with very high margins. Price differences are at least tenfold and for those suckers who buy ‘ready to use’ diluted spray the difference in cost might be a factor of hundreds. Legislation regarding amateur gardeners is a very grey area which suits our authorities fine.
I know very few gardeners who do not use professional glyphosate. With a little effort it is easily acquired. In my opinion it is one of the safest pesticides ever invented. (For the uninitiated ’pesticide’ is the generic word for all ‘plant protection’ products)
Even if you don’t take my word for its safety the professional product is only different to amateur products in its strength. When applied appropriately diluted to the weeds it is for all practical purposes the same. The good news is that if you choose to control with stuff from the garden centre it is equally effective. It’s just that it will cost you very much more. This will be as nothing compared with tens of thousands knocked off the value of your home.

Peter eliminated it with a single injection
My new post today was inspired by a letter to the Times describing how the householder eliminated JKW in a season with a cutting back technique that exposed the root system to the flow back of weedkiller to the roots via the hollow stems. I have not done this myself on JKW but have good reason to believe it works very well.

My reasons for predicting success

Equisetum hyemale - just as aggressive as the common marestail
I have used the technique very successfully indeed on mares tail, equisetum. Not actually the common weed species itself but on an equally deep rooted ‘impossible to kill’ relation Equisetum hyemale. It was taking over a six square metre patch in Bolton Percy cemetery. I did not want my own memorial to be a huge blot on the landscape and decided it must go. Not only did it completely go for ever after one single treatment, even untreated outlying spreading growth was completely killed as it sucked up the glyphosate from its deep root metres below

Cut back by hedge trimmer and ready to drench

I once read of a professional gardener who used the technique on the feared equisetum weed itself and although at the time I did not believe him when he claimed it worked very well I think he was not fibbing.

Six weeks later
Six months later - at this point it was mulched over

I described in my JKW control opus how Peter Williams eliminated JKW in one go by injection. This is rather fiddly but works extremely well. It succeeds by exactly the same principle as trickle back down hollow stems and subsequent root translocation.

Peter cobbled together this natty injector
My main post on JKW control has now accumulated almost a hundred comments. Although I was then unaware that the cutting back technique was a viable option several readers report great success with it.
I was also rewarded with many grateful thanks for pointing the way to eliminating JKW on their property by conventional spraying

How and when
Although I have not carried out the technique on JKW myself I go on general principles
JKW should be growing strongly when you first treat it. No use zapping when growth first appears in Spring. Little use either if you have recently been scrabbling out roots.
Perhaps optimum is to cut new 18 inch shoots to perhaps an inch to the ground (although it might start very much higher). If you have previously embarked on a spraying regime new growth might be very much shorter.
Immediately give a heavy spray For larger areas use a knapsack sprayer, for smaller areas any bog standard hand sprayer. Although a rose on a watering can is generally inappropriate to apply glyphosate to leaves it is suitable here. You want to apply enough spray to visibly penetrate down into the hollow stems.
I would dilute commercial ‘Roundup’ (any professional version of glyphosate) at perhaps one in ten dilution. That would equate to amateur product concentrate at one in one, two or three (product strengths vary).
I do not expect complete success with a first application. You might miss new growths and it might not be the optimum time. (You can start the procedure right through to late Summer). If there is new growth let it grow strongly before you repeat treatment.

With the more usual spraying techniques I describe in previous posts it takes at least three years of repeated glyphosate sprays to eliminate strong established JKW. With this new approach I expect it to be very much quicker
If you do not declare JKW as a house vendor you will not escape your responsibility to any new householder unless JKW is completely and permanently eliminated. No use in court if it was merely dormant

My post that details control of JKW by spraying has been read twenty five thousand times and includes in ‘comments’ reader’s  tips and questions

Although this post takes a different direction it includes many of the above observations

My original post on marestail/horsetail

Use my search box to read detailed dedicated articles on controlling epilobium (some misidentify as willow herb), ground elder, hairy bitter cress, hymalayan balsam and brambles  - which is the worst weed of all.

Thursday 3 October 2019

Batty about battery electric (in the garden)

My Black and Decker battery electric hedge trimmer
Remember the days of the drama when you cut the cable on your electric hedge trimmer? Remember all those connections as you strove to reach the end of a long hedge or the frustration when the cut out cut in?

Julie has moved on from hand shears
I am afraid I even remember when I cut my hedge with hand shears. (Still used by some expert  topiarising practitioners or pains-taking gardeners)

You might in desperation have turned to petrol driven hedge trimmers. So heavy and unless of professional standard gut wrenching starting and a lottery ticket for even starting at all.
I myself use a STHL model with some reliability (Despite when new, a faulty plastic tube quickly disintegrated to clog up the innards and the uncaring supplier cleaned up the symptoms but even when told failed to cure the cause.
Talented Peter Williams got me up and running).

To be honest although my petrol hedge trimmer gets quite heavy use cutting back end of season perennials and general ‘rough pruning’ and tidying, I have retired from cutting my seventy meter long hedge. Brenda says at my age I ought to pay a certain respect to advancing years and it is cheaper to pay Eric than downsize our home.
In truth he does it better.

Battery technology in recent years has so improved that you can use powerful light weight cutters that go a long time on one charge. You can have a cup of tea or do something else whilst it rapidly charges.

I write today about Peter’s recent experience with his new professional STHL electric hedge cutter and rather repeat myself from an earlier post about my wonderful Black and Decker electric strimmer.

Electric edges and flayed weeds
I have always been suspicious of petrol strimmers and sympathy with those who slave away cutting grass in awkward places all day. I have a dislike of two stroke petrol engines and a fear of constantly fumbling re-threading broken strings

Three years ago a former colleague visited my open day and was drawn to my six hundred meters of meandering lawn edges. I am not sure whether it was was sympathy or just well disguised horror. Years ago I had decided that long handled edging shears had been the best solution but even with sharp shears (thank you Peter) the edges lacked a certain ‘ne sais quoi’
My friend promised me a demonstration of his own Black and Decker electric strimmer. It was a complete revelation! With its monofilament line set vertical (I can fine no other word for the ‘cable’) it whizzed round the edges. Even I soon got the knack of how to use it.
Jim emphasised I should wear goggles for the very occasional flung ‘mud’ or very small stone. I now modify my technique to wander into small weeds in the bottom of my very shallow edge trench.
What a transformation. Even Brenda my consistent ‘advisor’ (and former edger before she hung up her boots) admires them.
What I should have learned years ago is that if used properly, modern electric strimmers automatically get to the end of their spool without human intervention!

I recently witnessed a similar  dramatic revelation when I took my strimmer to Bolton Percy churchyard and showed Jacky Giles how quickly it tidied up small weeds and soft vegetation. Her eyes shined as she saw its potential.

Black and Decker strimmer
30cm 36V 2.0Ah Lithium-ion Strimmer® Grass Trimmer

Stands ready
I don’t seek today to promote a particular product and anyway my own is no longer available. Do get one of sufficient power for your needs and I would go for no less  than the above specification. I get more than half an hour of continuous cutting and an hour or so if I am not in a hurry and stop and start to take out a weed.
I take a break or more often do something else whilst it recharges which takes about half an hour. The battery flashes a reassuring green whilst recharging and remains on its stand until needed again. Sometimes it flashes red which worried me the first time. Peter explained that is what is meant to do and indicates it is nearly fully discharged - which is no sin.

You will have gathered that I now use it for many more things than originally planned; particularly small annual weeds. I align the line vertically most of the time but you will find you discover the best orientation for differing small tasks.

I have a foolish ambition to get rid of coarse grass weeds in my lawn and I find if used to cut in vertically on my sandy soil my strimmer is an absolute godsend and perhaps in a decade or so my lawn will be all fescue

This fescue grass path has been mown once and strimmed once in the two years since sowing

I hope you will have read about my successful use of un-mown pure Chewing fescue stands as grass paths running into my large borders and as a foil to plants in Cathi’s grass verge and in Lyndi’s grass field.
I can struggle into the fescue grass paths and patches once or twice a year with my mower in my own garden and on the village plot but find the strimmer a good substitute and a real boon if I want to cut back the fescue grass after flowering in the other grass features.

Please note my own electric strimmer does not have enough power to 'mow' normal long grass, nor to cut back thick herbaceous perennials for which I still use my hedge trimmer. For all edges it is terrific.

I guess many of my readers have a much greater experience of electrical garden aids and would love to hear your comments. Should I now be considering a battery operated mower?

Peter’s hedge trimmer

He has just splashed out £400 on a super dooper electric hedge trimmer. It is a more powerful cutter than his previous petrol one and cutting his ‘miles of hedge is pure pleasure (I exaggerate the ‘miles’ and even the ‘pleasure’). It goes almost two hours on a single charge.
I feel very tempted.

A beautiful cut

They have been clipping with this small  trimmer for topiary work for several years now

If you would like to read more about how I use Chewings fescue in my garden

If you would like to read more about my use of the Black and Decker strimmer

Related Posts Plugin for WordPress, Blogger...