hedgehogs' road sense

[Gian]

Im not a scientist, but as far as I know species have been evolving over about 3 billion years?

 

But am I right that it can also occur quite rapidly, eg changes in the teeth of urban foxes, or hedgehogs acquiring roadsense?

 

cheerz

 

GIAN

[studiot]

Would you not say that the emergence of life itself, ie the event which produced the very first organism, was a pretty dramatic and sudden step in evolution?

 

I venture to suggest that sudden dramatic steps are easier in simple organisms and happen frequently such as the evolution of drug resistant microbes.

 

Evolution in complex organisms is more likely to proceed at a sedate pace, though sometimes the result is similar eg warfarin tolerant rats.

[Ringer]

It depends on what you mean by rapidly, and I'm unsure of the examples you gave could you provide links? Things may be able to evolve relatively rapidly, the punctuated gradualism model of evolution explains processes of fairly rapid evolutionary change.

Would you not say that the emergence of life itself, ie the event which produced the very first organism, was a pretty dramatic and sudden step in evolution?

Technically this isn't evolution, it's abiogenesis. Evolution only deals with things that are already alive and have a population.

[studiot]

Technically this isn't evolution, it's abiogenesis. Evolution only deals with things that are already alive and have a population.

 

 

I think the terms 'evolution' and evolve have a wider meaning than that

[Delta1212]

 

I think the terms 'evolution' and evolve have a wider meaning than that

In common parlance, yes. Scientifically, not in the context of biology.

[overtone]

I think the terms 'evolution' and evolve have a wider meaning than that

In common parlance, yes. Scientifically, not in the context of biology

Darwinian evolutionary theory provides the current best accepted scientific approach to abiogenesis.

 

Whether abiogenesis belongs in the context of biology might be debatable, but attempted employment of Darwinian theory to such events is not - it would be the standard scientific approach.

 

Darwinian theory has found application in many fields of inquiry, some far removed from biology.

 

In my area squirrels living in towns tend to run in straight lines when startled by cars, squirrels in rural areas tend to zig zag. and double back. This is a reflex, not a decision, by the squirrel.

Edited May 27, 2013 by overtone

[Ophiolite]

It is one of the generally unmentioned truths that pre-biotic chemistry was likley subject to Darwinian selection. The rather consistent silence on this has a few possible causes.

 

The evidence for evolution was growing in the century before Darwin, so that broad acceptance in the scientific community occured rather rapidly. The same could not be said about the origin of life - no evidence and nothing much more, till Oparin and Haldane, than Darwin's "warm little pond" and very large if. So, the two were very distinct and seemingly rightly separated. Note also, that the complexity of even the simplest life was not properly understood. Though an extended process rather than an event was required, this was not fully appreciated for a considerable time.

 

Creationists like to attack Darwinian theory on the basis that it does not explain the origin of life. This has led to the counter argument that seeks to clearly distinguish between the two.

 

The general public and other sciences use evolution in more than one way. This can lead to a zealous definition, sensuo stricto, to cover only biological evolution of existing life forms.

 

Personally, I think the separation of evolution from abiogenesis is a valuable one. While there are similar principles at work in both, there are important differences and these are worth distinguishing in the terminology.

[studiot]

I am not a biologist and acept that I may have taken the term evolution in a non biological way, although I was still referring to the core idea of a change that has produced something that has not occurred before.

 

Interestingly Darwin went on a famous long sea voyage at the time when evolution was a nuatical term that meant (and still does) something slightly different.

 

However my post also contained some suggestions what I understand concerning the core issue of the OP to be. That is

 

Can evolutionary change occur in (big) jumps as well as a continuous series of (very) small steps?

 

I must apologise to Gian if my answer has led to quibbling over terms and diverted the discussion away from this.

 

I saw the recent BBC programme (countryfile) that discussed the change in the behaviour of hedgehogs.

[michel123456]

(...)

 

 

I saw the recent BBC programme (countryfile) that discussed the change in the behaviour of hedgehogs.

I didn't. What's about the hedgehogs?

[studiot]

They visited a hedgehog sanctuary and rescue service.

 

Here the warden explained and demonstrated that the traditional defence mechanism of the hedgehog is to roll into a prickly ball and remain stationary.

 

This action has lead to large numbers of squashed hedgehogs that do this in front of oncoming vehicles on the roads.

 

Apparantly some hedgehogs have learned to run for their lives instead.

 

However this makes them vulnerable to cats and dogs etc who can then attack their vulnerable undersides.

Edited May 27, 2013 by studiot

[michel123456]

So it seems that hedgehogs can learn.

Is that evolution?

[studiot]

Is that evolution?

 

 

 

Fair question but is discussion well served by taking too narrow a definition?

 

For instance "discuss roads where a road is defined as having an asphalt surface" is pretty limiting.

[Delta1212]

 

Fair question but is discussion well served by taking too narrow a definition?

 

For instance "discuss roads where a road is defined as having an asphalt surface" is pretty limiting.

Yes. Because there is a very specific requirement for a new behavior to be considered evolved: it must be biologically rooted. A learned behavior is not genetically heritable and is thus not a result of biological evolution.

 

I'm inclined to think it probably is at least partially, if not wholly, rooted in genetics and vehicular hogslaughter is selecting against the rolling instinct. However, I do not know this for certain. Having a strict definition for what constitutes biological evolution provides us with a framework for how to determine whether the hedgehog's behavior is a result of natural selection, or from an innate ability of hedgehogs to learn new defensive strategies in response to their environment.

 

These are two very different processes, and using a definition of evolution that lumps both of them into the same category is far more restrictive than separating them because it effectively eliminates useful terminology that is used to distinguish between different processes.

[pwagen]

But am I right that it can also occur quite rapidly, eg changes in the teeth of urban foxes, or hedgehogs acquiring roadsense?

As Ringer said, it depends what you mean by "rapidly". You're not very likely to see a complete transformation in a few generations. However, in the span of a human lifetime, we can sometimes get some pretty impressive results.

 

An interesting experiment where this is shown is the Silver Fox Experiment, where they bred two very distinct breeds of foxes in only 50 years.

 

http://en.wikipedia.org/wiki/Domesticated_silver_fox

 

http://www.youtube.com/watch?v=EoB0pdhxfZs

[overtone]

 

So it seems that hedgehogs can learn.

Is that evolution?

A hedgehog almost certainly cannot learn to run instead of rolling into a ball in front of a car.

 

Any more than a squirrel is likely to learn to avoid doubling back when surprised in the open by a vehicle ( similar phenomenon from my area).

 

The only penalty for doing the wrong thing is death - too late to learn then.

 

I'm currently trying to figure out if there's some way to establish whether snakes are basking differently in urban areas than in rural ones - there's heavy selection pressure on both sides of that one.

[studiot]

Cockroach Evolution.

 

http://www.bbc.co.uk/news/science-environment-22611143

[Gian]

It depends on what you mean by rapidly, and I'm unsure of the examples you gave could you provide links? Things may be able to evolve relatively rapidly, the punctuated gradualism model of evolution explains processes of fairly rapid evolutionary change.Technically this isn't evolution, it's abiogenesis. Evolution only deals with things that are already alive and have a population.

These are just things ive heard, but i'll try to find some research for you

[Ringer]

Keep in mind that rapidly for evolution is in terms of genetic change over generations. If this activity is spontaneously found in a specific population with very high frequency it is most likely a behavioral change, not necessarily a genotypic one because a mutation like that is unlikely to become high frequency in a very short amount of time (if they're more likely to be killed by predators than cars so something that hampers predator reaction is likely to be selected against). A way to test this is to isolate samples of this population and see if they have the natural behavior or the test behavior. Then breed, preferably raising some with wild type behavior adults and some with mutant adults, that population to see if that reaction is conveyed to later generations.

[overtone]

If this activity is spontaneously found in a specific population with

very high frequency it is most likely a behavioral change, not

necessarily a genotypic one

Population wide behavioral change in genetically controlled behavior (startle reactions in shortlived mostly solitary animals, say) is almost certainly reflected in a genotypic change of some kind.

 

Squiirrels don't learn to double back when a dog catches them in the open, but not when a car catches them on the road. They do whatever they are set to do, and survive or not in consequence. There is no trial and error and correction - all survived trials are successful ones, reinforcing whatever behavior was performed.

 

Likewise with hedgehogs, I imagine.

Edited May 29, 2013 by overtone

[benevolenthellion]

less road sense, more move away from the huge object, sense, which I think existed way before cars.