All the World's Deer: The Red Deer Species Complex

Red deer

When the first list of scientific animal names was drawn up in 1758, all six known species of deer were placed in the genus Cervus - which is, of course, simply the Latin word for "deer". Over the following decades, as taxonomy became more refined, all but one of those species were moved to other genera, and when the deer family, Cervidae, was named in 1810, it had roughly the same meaning that the genus had had so many years before. As its name implies, though, Cervus was selected as the type genus of the family - the one that defines the archetypal group against which all others are compared. Although newly described species had been added since, the one species that was so obviously deer-like it had never been moved anywhere else thus became, in a sense, the defining species of its family.

The Crab-Eating Fox That Wasn't

There are many species of "fox" native to South America. I covered all of these in a series on the dog family a few years ago and I noted at the time that they aren't really foxes in the sense of being related to the likes of red, Arctic, and fennec foxes. Instead, we know from both genetic and anatomical studies that they are more closely related to the group that includes wolves, jackals, and coyotes. 

The dog family has its origins in North America and it seems clear that what happened here is that some wolf-relative that happened to look a bit like a fox headed south at some point, where all of its remaining descendants live today. North and South America joined up relatively recently, geologically speaking, so it's likely that the origins of the South American foxes actually lie in the North, already looking somewhat like their modern form before they made the trip.

The Tyranny of the Bruce Effect

Monogamy is a relatively rare phenomenon among mammal species. It tends to occur where it requires considerable investment to raise children, whether that be in terms of supplying food over a long period, or careful protection from external threats. If you can spread that effort between both parents, the child is more likely to survive and the species to be perpetuated.

That's common in birds, perhaps in part because they have to physically fetch and deliver food rather than producing milk with the calories from their own diet, not to mention the effort of incubating eggs. But, in mammals, while it certainly occurs in some species (as do the other two options) the most common pattern is polygyny. 

The Toxic Life of an Unusual Rodent

As I've often mentioned before, the largest mammal family, by number of species, is the mouse family, or Muridae. Containing around a quarter of all known mammal species, it's vast and, in many cases, the species are so similar to one another physically that they can only be told apart by genetic analysis. A few years ago, I reported on the largest attempt to determine how this great array of species are related to one another. That particular scheme showed three main evolutionary lineages within the family.

By far the largest are the "murine" or "typical" mice which contains... well, almost everything. According to that particular study, they split from the other members of the mouse family about 18 million years ago, during the Early Miocene. Then, about 16 million years ago, as the Middle Miocene dawned, the remainder split into what are now recognised as two distinct subfamilies: the gerbils and the "deomyine" mice. (The latter look almost exactly like the murine sort, and it took this sort of study to prove that they weren't).