I live in a mixed rural/suburban area and thus I do get to see a lot of road kill. After seeing a new dead raccoon practically every week I started to wonder when would there be smarter raccoons as a result of this? There are about 4 main species that I see as road kill where I live, Prairie Dogs are the most common, followed by Raccoons, then the occasional Skunk, and very rarely do I see a Fox that has been hit.
One unique thing about the Prairie Dogs is that they are not nocturnal, they are only out during the day. So even though they don’t deal with the “deer in the headlights” syndrome they are flattened a lot more than anything else around here. It may have something to do with how dense their population is. Raccoons by most accounts are very smart, but crossing the road at night seems to be way too much for them to handle. I think it may have something to do with how slow they move. Skunks seem to not be as common, but you really notice it when they are hit. I’ve never heard a skunk described as smart. Foxes are both smart and fast, which is why I think they get hit less often. There is a Fox den only 100 yards from my house, which is also near a busy road, so I know they are good at avoiding the cars even though they are only out at night. I can’t recall a recent time that I have seen a dead fox, plenty of live ones though!
So the question is what traits are being selected in those who do not fall victim to road kill, & how long until those traits become common?
IIRC from how slow the process of evolution is, it’ll happen long after our grandchildren are dead. Maybe that small population would get smarter, but maybe they’d just be getting used to watching for cars, or something.
Around here it’s the “slow and stupid squirrel” season. With pigeons a close runner-up. Oddly enough, the crows that feed on all these squashies almost never get run over.
Sure, this is driving evolution, and not necessarily that slowly. Evolution is often invisibly slow partly because species have already been evolving to match their niches, so they’re pretty close to being a good fit and the forces carrying them further are pretty small. But if there is a sudden change in those environmental forces, such as a new highway being built through the habitat, they could evolve very quickly if there is already significant variability in the newly important factor to take advantage of.
An extreme example is breeding. Say you want cats with white fur, and you have a farm loaded with stray cats of all colors (which until now have conferred no difference in survivability). Suddenly you provide ideal breeding conditions for the white ones and discourage breeding for all the others. Each generation would have significantly more white cats - the effect would be immediate in terms of generations. And, yes, breeding is a special case of evolution. The fact that people are planning it does not change the situation; some random genetic versions are favored over others and therefore become more common.
It will more than likely show up in the scavengers that eat carrion before anything else.
The younger birds etc will become dependent on road kill for food.
I’m thinking that is much more likely than developing prairie dogs with little bumpers.
I have seen a film of a fox waiting beside the road watching the traffic like a 12 year old kid. When the cars were out of sight, (s)he crossed. Yes, evolution is continuing. It’s just that most of us don’t know how slowly it evolves.
This reminds me of a SF story (can’t remember the title, the author might have been Larry Niven). It was about a world in which due to lack of resources, the first intelligent species to evolve remained at the hunter/gatherer level for a very long time- tens of millions of years. Their presence caused a strong selective pressure for animals to become smarter to stay competitive, and as a result most of the higher animals on the planet were either sentient or very smart.
Spider Robinson did a story about a group of chickens marooned on a large “island” of land in a busy freeway area.
Over the generations, they develop from superstition to a “Rennasiance” to a technology level greater than ours. All this speeded by the attrition of cars & their shorter lifespans. The story is told in excerpts from interviews with passerbys.
This story is important, because it reminds us that evolution works much faster in creatures with short lifespans.
It isn’t the number of years that matter, it’s the number of generations. The quicker you reach breeding age, the more time you have to pass on your genes. If your genes offer an advantage; say, avoiding cars, your decendents will “evolve” , over a period of X years.
Natural lifespans. Dying at a relatively young age compared to your species natural lifespan won’t pass your genes along any faster. What if we started killing lots of human babies, surely you don’t think that would make us evolve faster.
LokiTheDog has indeed missed Bosda Di’Chi of Tricor’s point.
Bosda Di’Chi of Tricor’s comment is correct. Scientists use fruit flies to demonstrate traits because their life spans are so short and results can be seen quickly. If they were to use giant sea turtles, we’d still be messing around with Mendel’s premises.
Here in the South, the main roadkill is possums, armadillo, and raccoon.(Yeah, I notice this, mainly because I was raised by biologists who would screech to a halt to see if the “specimen was salvageable”. Our home freezer was pretty strange.)
Of these, the possum has the defense adaptation of freezing (“playing possum”) which doesn’t work particularly well against oncoming headlights. Ditto for armadillos: their defense mechanism is to spring upwards when alarmed. This may surprise a predator: but it ain’t worth a damn against an 18-wheeler.
I’ve always wondered, though, why the beasties are always glimpsed on the side of the road. You rarely see them splashed on the middle. Any answers for that?
As for raccoons, I’d guess that they generally have adapted and thrived in places where people do, so are more likely to cross roads.
Well, the animals would probably have to have this selective pressure hanging over them for many generations, if they were to become “better” at avoiding cars. Most likely something else that humans did might make them go extinct anyway. How fast this would happen, really would depend on how well isolated these animal populations were from other members of their own species.
If gene flow between different populations outside the area was minimal, then a favorable mutation which resulted in altered behaviour leading to decreased mortality rate from autos, might become fixed the population by natural selection in a relatively short period of time. How fast would depend on the species.
