Coffee with the squirrels today: They don't give their kids mating advice

Red squirrel, Tamioscurus Hudsonius

Staff writer Lesley Ciarula Taylor explains for Toronto Star readers "Why female red squirrels aren’t choosy about their mates":

Guelph scientists have solved the puzzling question of why female squirrels are rampantly promiscuous, sleeping with an average of 10 males in one day.


It almost entirely depends on how many guys show up.

That's the finding reported by University of Guelph researchers from their study of 85 female North American red squirrels. Female squirrels do not pass any specific mating tendencies (one, some, or many guys) on to their daughters.

"A lot of folks who have looked at this before looked at whether it’s good or bad for a squirrel to be promiscuous," [lead investigator Eryn] McFarlane told the Star on Wednesday. "I wanted to look at whether it was genetic, regardless of whether it was good or bad."


What she found is that risks and benefits don’t have much to do with how females behave.


[ ... ]


This is the first study that says genetics or heredity have little to do with a female squirrel’s sex life.

Goodbye, selfish gene. Or, to put it in the vernacular, none of the ladies are chaste, but some are more chased than others. It depends on how many guy squirrels are around to chase them.

For the tale of how the Washington Post thought it had discovered natural selection among squirrels, go here.

Look, squirrels are, well, squirrelly, but anyway here's the Abstract:

The tendency of females to mate with multiple males is often explained by direct and indirect benefits that could outweigh the many potential costs of multiple mating. However, behaviour can only evolve in response to costs and benefits if there is sufficient genetic variation on which selection can act. We followed 108 mating chases of 85 North American red squirrels (Tamiasciurus hudsonicus) during 4 years, to measure each female's degree of multiple male mating (MMM), and used an animal model analysis of our multi-generational pedigree to provide what we believe is the first estimate of the heritability of MMM in the wild. Female red squirrels were highly polyandrous, mating with an average of 7.0 ± 0.2 males on their day of oestrus. Although we found evidence for moderate levels of additive genetic variation (CVA = 5.1), environmental variation was very high (CVE = 32.3), which resulted in a very low heritability estimate (h2 < 0.01). So, while there is genetic variation in this trait, the large environmental variation suggests that any costs or benefits associated with differences among females in MMM are primarily owing to environmental and not genetic differences, which could constrain the evolutionary response to natural selection on this trait.

The Washington Post thinks it has discovered natural selection.

Apparently, 18 black Canadian squirrels were released at the Smithsonian in Washington D.C. in the early 1900s. As anyone who has lived in Toronto would predict, they soon began to jostle the local gray squirrels at area bird feeders.

The Post writer announces,

That's because those 18 squirrels -- whose coats of lustrous black set them apart from the native animals -- were the beginning of a shift that has changed the complexion of Washington's backyard critters. Now, probably because of a slight evolutionary advantage conveyed with a black coat, the descendants of these squirrels have spread all the way into Rockville and Prince William County.

Seriously: Scientists say it's a real-life example of natural selection at work, which has rolled on for a century here without much public notice.

"It shows the spread of a gene within a population," said Richard W. Thorington Jr., a Smithsonian Institution researcher working on a book that includes a history of the District's black squirrels. "That is evolutionary change before your eyes."

Wow. Seriously? Evolutionary change before my eyes? But wait a minute ... The Post writer then goes on to say,

The story of Washington's black squirrels -- which scientists say are just a color variation within the common gray squirrel species -- still has its shades of mystery.

Yes, that’s right, folks. The grey and the black squirrels are actually two coat-type varieties of the same species. They are about as different genetically as black and white alley cats are from orange and white alley cats.

Here in Toronto, the two coat types have persisted together for many decades, doing a proportionate amount of damage to spring flower gardens and native bird feeders. But apparently in the Washington area a century ago, for some reason, only the greys were found, until a zookeeper acquired some of the black variety from Canada and let them go.

In a classic example of Darwinian just-so storytelling, we are informed, "Here's why some scientists believe the black squirrels were multiplying: In winter, their dark coats allowed them to retain heat from sunlight, leaving them less desperate for warmth than their lighter-colored cousins."

Well, if that is the case, why do the supposedly disadvantaged grey-coat type squirrels survive at all in cities like Toronto that can become much colder than Washington? Yet their relative proportion of the squirrel population here does not seem to have changed much over the decades.

In reality, the black squirrels are multiplying in Washington because that’s what squirrels do, given a chance. In Toronto, the black squirrels tend to be somewhat more numerous than the grey, but unlike the Darwinists, I am not going to offer a just-so story as to why that is so. A genome map might possibly demonstrate that black is the dominant colour, but I don’t know of any such map in existence now.

Oh, by the way, do the squirrels even care which coat type they are? One scientist explains,

"... the squirrels don't appear to treat each other differently because they are black or gray." "They don't seem to care," he said.

Personally, I can’t imagine why the squirrels would even know, let alone care.

The key thing to see here is that the Darwinist wants us to understand that the process that (he hopes) can explain why pesky black-coat-type squirrels can get established in the Washington area alongside grey members of the same species can also explain the entire history of life. But he never demonstrates that point, he merely assumes it as an article of faith. And he then expects the rest of us to take these utterly trivial instances of animals adapting to an environment as evidence for his thesis. No wonder they are restless over there in Kansas.

To find out more about my book on the intelligent design controversy, go to By Design or by Chance?