Aussie evolution - feasible?

[Thylacoleo Gal]

arts said:

According to govt reports, Australia has an estimated 12 million feral cats running wild. Thousands of these cats are supposedly killed each year in an attempt to cull the population.

So, with a feral cat problem that huge and thousands being spotted and killed by humans each year, how is it some are attributing the presence of cats that are at least five times the size of an average feral cat, to being feral cat?

Domestic and feral cats are not native to Australia and were introduced with white settlement. Therefore the introduced cat population have been breeding here in Australia for only about 215 years. That's somewhere between 20 & 30 generations of cat. Yet it has been suggested small pools of those feral cats have managed to increase their size to five and ten times their original size within 30 generations from when they first landed here.... and not even the slightest size increases have been observed in any domestic or semi domestic cats worldwide despite extremely healthy diets available to them........

A "healthy diet" won't increase any critter's size beyond its genetic limits. Of course, if they get too much, you get the "fat cat" syndrome - and you see that happen to certain humans, right? What would increase body size in a small "pool" is natural selection. The question is, how fast can it act? Is 20 - 30 generations enough? No one's suggesting an increase by a factor of 10. But 3, maybe 4 times, mean body weight - is that sort of increase feasible? What might be the factors driving the selection?

[Wally1]

This is a question that I have been trying to answer for many years.
From behavioural pattens that I have observed in the bigcat it is similar to what I have read about the African wildcat F lybica. I will still stick to my theory that cats were brought to Aust during the Egyption/Phoenecian occupation, 4000/2500 YBP. Same applies to the mallee Dog. Before anyone rushes in to print to suggest that I have Rexitis, I do not know Rex and have never communicated with him. My time factor was obtained from other Egyptologists who estimated the time factor from differing styles of writings found carved in rocks being compared with scrupts of known age found in Egypt.
If I cannot be proved right, stand up the man who can prove me wrong.
I have found foxes that ranged from midgets no bigger than big rabbits to foxes that can outrun most dogs except very fast hounds and more than hold their own in a fight with most dogs. These changes occurred within 150 years.The big foxes have evolved mainly in the last 20 years since the big cats came out of the woodwork or should I say woods. The foxes predate rabbits and hares in the open country adjoining forrest and big cats predate the foxes so the fastest runner either catches a meal or survives to hunt another day.
Chers Wally

[Wally1]

Predate should read predatored (OK Hobbes).
Regs Wally

[The Doc]

While I don't believe there's any credible evidence - who do I have in mind here? ;D - of Egyptians or other ancient "high civilisations" having established permanent colonies or bases along Australia's coasts, it's not something we can dismiss out of hand. The rapid colonisation of the Pacific by Polynesians is relevant imho because its date at about 4000 years ago corresponds to the final diminishment of the sea to it's present level. See - www.tuvaluislands.com/history-caves.htm

Before that, levels had risen during the early to mid-Holocene by something around 2 - 6 metres (? not sure?) and this rise would have obliterated many or most of the low lying islands in the mid-Pacific that served as staging posts for the Polynesian voyagers. The fact the central Pacific was colonised as soon as the subsiding waters made land available might indicate that advanced trans-oceanic sailing technology was to hand well before the 4000 year mark. In which case Australia could have been within reach anytime from the beginning of the Holocene. Perhaps even earlier?

However, if exotics like Asian cats had had been introduced at an early date, they would have been reported by the first European settlers. They weren't. So what are we left with?

[Wally1]

I wont enter into any arguments but would like to point out salient facts which anyone can see for themselves.
Who may I ask was responsible for the Egyptian and Phoenecian writing that can be found carved on stone in many parts of Australia. Now dont try to blame it all on grafiti artists . There are other web sites besides
"that one" belonging to independent authors who write about their findings of objects of great antiquity, some of which have been found deep in the ground
There is Phoenecian script to be found in the Flinders Ranges and carvings of ancient style ships to be found in Sturt's Stony Desert.
There is plenty of evidence of settlement prior to British occupation to be foud including Spanish in Sydney area.
However all this is conveniently overlooked in the public annals.
Cheers Wally

[Deleted]

There were Egyptian artifacts discovered in WA many years ago, I don't know what happened to them. There is also the Roman writer Pliny who accurately described a kangaroo in 70CE, of course he did qualify the report by admitting that no such animal could possibly exist. ;D

[Sean]

Biological evolution by natural selection IS feasible...one of the greatest of scientific theories, and one of the most accessible to the lay person to understand. Unfortunately, its mechanism is sometimes misunderstood as a result of oversimplifying its processes, and people attempt to interpret it by assuming it is driven by the individual's desire to improve itself (eg, the animal ' adapts ITself to the environment') as if it can recognise within itself more desirable features. Or, instead, the environment designs the organism, without appreciating the significance of how this wonderful process actually works.
Our features are determined by a combination of our DNA and how the environment may allow this DNA to be expressed. Also, not every individual has equal chances of survival. So, which individuals are more likely to survive, and which will perish (and eliminate unfavourable DNA?).
Genetic variation persists within every (especially sexually reproducing) species and the selection pressures that may operate within any one environment will eliminate potentially every individual possessing DNA that does not increase its chances of survival. This occurs in the face of those individuals that have randomly inherited more suitable (rather than saying the 'fittest', which may suggest, inaccurately, to some, improved muscular ability, ferocity, or in this case, increased size) DNA. The accumulation of such a selection process over many generations will inevitably alter the genetic constitution of the species (its gene pool) leading to the evolution of a better adapted population/species.
As Debbie stated, an improved diet will assist the DNA to attain their maximum effect when determining the features of an organism, but not alter their gene pool. This hints on Lamarckian evolution, that is, an organism acquiring desired features within the course of its lifetime. The average size of Asian people has increased markedly since they have begun to consume nutrient-rich western-style diets, but to a size no larger than the average human. They always possessed the DNA, just that their diets prevented the DNA's complete expression regarding growth.
There is no distinct advantage in evolving to a larger size unless there are environmental factors that will favour it. Larger organisms require more resources, especially food, and Australia is recognised as being, comparatively to other regions, nutrient poor. Tim Flannery's 'The Future Eaters' emphasises this feature. Evolution has also selected against the persistence of large animals (megafauna) within Australia, and elsewhere, over recent millenia.
Unfortunately, stating this will attract the disinterest of those preferring not to believe in this process, in preference of something more emotionally-appealing and anthropocentric and dogmatic processes. I prefer to believe in evolution's reality. It may have apparent 'gaps' and 'holes', but which scientific theory may not? These anomalies are filled as our knowledge and technology improve. We do not know everything yet, nor will we ever. Imagine a world without mystery, or wonder. These are often the forces that make life so exciting. Finding things out, especially rapidly and easily, dulls these sensations!
Testable hypotheses that are repeatable in the absence of subjective design is indisputable. But I wish to intimidate no further.
I hope there are many who also feel as though they cannot agree to many of the arguments mentioned on this forum whose belief is based on, unfortunately, poor evidence, untestable ideas and an overwhelming desire to be correct without supplying suitably documented evidence.
And I know I'm gonna cop some criticism for that!!!
Cheers,
Sean

[Molloch]

A generation for cats is only 12 months. A kitten is capable of producing viable offspring at 6-8 months of age. Therefore we may have had 200 genrations of cats. Given that cats will give birth to 3-5 viable young, and will usually breed twice (or 3 times) a year - this is quite an opportunity for some genetic diversity. Look at the different size, shapes and deformities of dogs we have been able to selectivly breed in the past 200 years.

Healthy, abundant diets are counter productive to favouring increased size for cats. Cunning, agility and size will be much more likely to be selected for hunting reptiles, birds and possums.

As I stated elsewhere, i have seen cats around 12 kg in size, generally from areas well out of suburbia, one from Wentworth was probably one of the biggest. These cats are lean, muscular, usually male, very agressive - will lunge at you forcefully if cornered - but are most definatly domestic cats, the normal, average size for which is probably 4 kgs.

Having spent some time working in Aboriginal communities in NT, may different groups have aboriginal names for cats. Most of these though can be traced to variations of English words (pussycatto in Anindilyakwa (Groote Eylandt)), some however, are completely unusual. If cats made it to Australia before white settlement, I doubt it would have been long before - we just had too much small, edible wildlife 200 years ago that is gone now. They may have been introduced slightly earlier on trading ships which were known to have visited the NT aboriginal tribes.

[Wally1]

Hi
There is something that I would like to comment on.
Nutrient poor. The current Australian herbage eating
fauna is adapted to sutvive in a nutrient poor environment
I have seen times when all sheep and cattle had starved or perished to death but the kangaroos were still there, they were in bloody poor condition but still surviving.
So when the primary source in the food chain is surviving, I dont see how nutrient poor conditiond can effect the predators.
The yellow foot wallaby was almost eliminated by destruction of food source by rabbits and goats. When these ferals were eliminated, or reduced in
numbers the YF wallabies have bounced back and are a food source for wedge tailed eagles.
No matter what the nutriment condition is there are still termites munching on fibrous debris and other insects which feed the mini fauna, which feed the larger echelon of predators, the quolls. Apart from thylacines, Tassie devils, ( how I hate that term) and perhaps TC, the quolls would be fairly safe. The top of the food chain in most of Aust.
Until British occupation there were no introduced ferals except, the cat, and the dog
There is evidence that Asian type cats were introduced into Northern and NW areas of Aust at an early date.
I will comment on this again when I dig out the relavent paper work. Also I theorise that cats were introduced at an early date by Egyptian settlers who came searching for metals such as copper tin and gold.
These cats would have to compete with the quolls for food and judging how a big quoll, perhaps a tiger quoll did over the local tomcats, leaving many dead or dying,near a NSW town on one occasion,
the cats would have a hard time.
There was one niche still there open for predation, the kangaroos, So what can the cat do, get bigger, big enough to predator small roos then big enough to predator big roos. A forced evolution so to speak, so we now have a major predator at the top of the food chain. Admittadly we still have thylacine, devil and TC, but their ranges and numbers are extremely limited and connot compare with the numbers and Australia wide range of the big cat.
A question can be asked, are they still evolving into even larger animals. predation of large animals such as cows and horses is becoming common. In the past the only animals predating large farm stock were dog packs, but the cats are killing these large animals single handed. Where will it end
Regs Wally

[Thylacoleo Gal]

Sean said:

Biological evolution by natural selection IS feasible...one of the greatest of scientific theories, and one of the most accessible to the lay person to understand. <..>

people attempt to interpret it by assuming it is driven by the individual's desire to improve itself (eg, the animal ' adapts ITself to the environment')

Yeah, that's a common misperception about "evolution". Individuals don't "evolve" : if you're born a platypus or a jellyfish or a human, that's what you're gonna be for all your born natural.

Australia is recognised as being, comparatively to other regions, nutrient poor. Tim Flannery's 'The Future Eaters' emphasises this feature. Evolution has also selected against the persistence of large animals (megafauna) within Australia,

Not sure if Steve Wroe The Palaeo would agree with that. From what I've gather from his writings, he reckons Prof Tim's got it all wrong, from megafauna extinctions to soil nutrients to large animals, or alleged lack thereof, in Pleistocene Sahul.

Unfortunately, stating this will attract the disinterest of those preferring not to believe in this process, in preference of something more emotionally-appealing and anthropocentric and dogmatic processes. I prefer to believe in evolution's reality.


Good for you - the theory of Natural Selection was indeed proposed in order to account for the observed facts of evolution.

And I know I'm gonna cop some criticism for that!!!

Not from QfT you're not!

[Thylacoleo Gal]

Molloch said:

A generation for cats is only 12 months. A kitten is capable of producing viable offspring at 6-8 months of age. Therefore we may have had 200 genrations of cats. Given that cats will give birth to 3-5 viable young, and will usually breed twice (or 3 times) a year - this is quite an opportunity for some genetic diversity. Look at the different size, shapes and deformities of dogs we have been able to selectivly breed in the past 200 years.

Healthy, abundant diets are counter productive to favouring increased size for cats. Cunning, agility and size will be much more likely to be selected for hunting reptiles, birds and possums.

As I stated elsewhere, i have seen cats around 12 kg in size, generally from areas well out of suburbia, one from Wentworth was probably one of the biggest. These cats are lean, muscular, usually male, very agressive - will lunge at you forcefully if cornered - but are most definatly domestic cats, the normal, average size for which is probably 4 kgs.

Having spent some time working in Aboriginal communities in NT, may different groups have aboriginal names for cats. Most of these though can be traced to variations of English words (pussycatto in Anindilyakwa (Groote Eylandt)), some however, are completely unusual. If cats made it to Australia before white settlement, I doubt it would have been long before - we just had too much small, edible wildlife 200 years ago that is gone now. They may have been introduced slightly earlier on trading ships which were known to have visited the NT aboriginal tribes.

I don't know if I'd put any faith in "traditional" aboriginal claims about native species. Feral Future - ?author? - tells that many aboriginal people claim as "traditional" or "native" species that are known to have been introduced in European times.

A 4kg -> 12kg range in ferals is within the variability you see in dogs, eg Chihuahua vs Great Dane. The question is, what isolating mechanism is involved? Australia seems like an ideal laboratory to see evolution in action because you have many foreign species introduced into novel environments plus fragmented native populations that are subjected to new selective pressures - loss of habitat, exotic predators & diseases, new vegetation and so on. It's definitely something to keep an eye out for.

The snag is that there are not very many geographical barriers to dispersion and sympatric speciation is supposed not to happen in mammals. If you could find an example of it, that'd be something worth writing up!