Alien supreme ruler of his rapid evolution planet

Question

This was a novelette length story I read about 40 years ago in the UK, I can't think of any other stories that were in the anthology book.

The supreme massive alien creature is patrolling his territory on his world, other beasties are signalling submission to him in various ways (including radio and laser) as he goes about his business.

He is continually spraying out suppressant fluids as he moves, this is to slow down evolution because the lifeforms can evolve very rapidly.

The exploratory team from Earth lands so he takes cover to observe this possible threat from hiding, the scientists are puzzled by the massive array of different aggressive species but after a couple of fights with advanced weaponry a dissection or two put them on the right trail.

They capture another creature and subject it to some kind of constant harmful radiation, it eventually dies but ejects an egg as it does so, the egg hatched into a modified version that is now immune to the radiation - they have evolved it. They experiment in similar ways several times but then decide to leave, they categorise the world as too inhospitable and put out a warning satellite to stay away.

Back on alien planet the supreme entity evolved into a truly massive creature to prepare for combat with the explorers when they return, unaware that they're never coming back. He creates super highways all over his world so he can rapid response wherever they'll land. He has lesser beings drilled up for attacks and developing weapons. Then he waits and waits and waits

Answer 1

Mutation Planet by Barrington J. Bayley, published in 1973. I read it in the anthology Tomorrow's Alternatives.

The story is exactly as you remember. The alien is called Dominus and the story starts:

The vast and brooding landscape, filled with ominous mutterings, ground-trembling rumblings, stretched all around in an infinity of gloom. The mountainous form of Dominus moved across this landscape at speed, like a massy shadow, heavy with power and sullenly majestic. Above him the opaque sky, lurid and oppressively close, flared intermittently and discharged sheets of lightning that were engulfed in the distant hills. In the instant before some creature fed on the electric glare, the dimness would be relieved, outlining endless, uneven expanses of near-barren soil. Dominus, however, took no sensory advantage of these flashes; his inputs covered a wider, more reliable range of impressions.

As he sped through his domain he scattered genetic materials to either side of him. These would dampen down evolutionary activity for miles around and ensure that no lifeform would arise that could inconvenience him or interfere with the roadway over which he moved. Built by himself as one of the main instruments of his control over his environment, this roadway spanned the whole eight thousand miles of the planet’s single continent, and was a uniform quarter of a mile wide; side roads diverged, at irregular intervals, into the larger peninsulas. Since the substance of the roadbed was quasi-organic, having been extruded by organs he possessed for that purpose, Dominus could, moreover, sense instantly any attack, damage, or unacceptable occurrence taking place on any part of it.

It ends with Dominus preparing for the invasion it is sure will come:

With that realization an urge beyond all power to resist came upon Dominus: the compulsion to evolve. He meditated in the, depths of his being, and the entity to which he ultimately gave birth, amid great explosions, agonies and devastations, was as far above him in ability as he had been above his immediate inferior.

The new Dominus immediately set about the defence of his planet. The whole of the single continent became a spring-board for this defence, criss-crossed with artifacts which meshed integrally with the space-borne artifacts ranging several light-years beyond the atmosphere. To crew this extensive system Dominus copied the methods of the invader and created armies of slave doll-organisms modelled on the enemy’s own doll-organisms.

And Dominus waited for the enemy to arrive.