Species specifications: how one mouse becomes three – Biology News

The delicate mouse is a species of native rodent widespread in northern Australia.

Or at least it was.

No, no, don’t worry, it wasn’t wiped out by some catastrophic disease or misplaced bulldozer. Scientists recently discovered that Australia’s delicate mice are actually three different species!

The delicate mouse species has now been split into the northern delicate mouse (Pseudomys delicatus)the western delicate mouse (Pseudomys pilbarensis) and the eastern delicate mouse (Pseudomys mimulus).

OK and…?

Hooray for science, we have two new species, but why does that matter? And how did those researchers even come to the conclusion that they were separate species?

WHAT MAKES A SPECIES?

There are many ways in which one species can become two along the branches of the evolutionary tree. Most often, speciation (the development of new species) is caused by geographic isolation.

When different groups of the same species are physically separated by, for example, mountain ranges, oceans or deserts, this prevents the different groups from breeding with each other.

Initially, they are still considered the same species. But after generations of separation, unique mutations that are not shared with other groups begin to appear in each group.

Perhaps one group develops a longer nose or another group becomes more heat tolerant.

Or maybe a group starts speaking cool new slang and making jokes that the others don’t understand. No, just delete that. This is what it feels like to talk to people from Melbourne.

In any case, eventually enough mutations have occurred that the groups can be quite different genetically and physically.

But the real deciding factor that splits one species in two is when different groups can no longer have viable (will survive) and fertile (can have babies) offspring with each other.

Here’s what we think happened to the vulnerable mouse, with groups separated by the vast expanse of inland Australia, and why scientists decided to split them into three species.

CATEGORY IS: TAXONOMY

The study’s lead researcher, Dr Emily Roycroft from Australian National University, explains what led to their decision.

“The three vulnerable mouse species are genetically different from each other. This probably prevents them from interbreeding. Together with subtle morphological differences, this led to the conclusion that they were different species,” says Emily.

That may sound a bit complicated, but genetics often plays a role in making taxonomic decisions.

Taxonomy is the science of naming and categorizing different organisms (not to be confused with taxidermy, the stuffing and mounting of those organisms). There is no single reason why taxonomic categories change, but genetic analysis is increasingly being used to pick apart the evolutionary tree. New genetic technologies and techniques can show us how evolution has separated different species or how they may be closer together than we thought.

This happened in WA in 2007, when a genetic analysis revealed that the plant genus Dryandra was actually just a branch of the genus Banksia rather than a gender in itself.

Scientists have made the decision to merge Dryandra go inside Banksiabut many frustrated hobby gardeners wondered why this was necessary.

Was it just scientific pedantry?

We may know How These decisions are made, but why bother changing things at all? What does it matter?

WHY SPECIES ARE IMPORTANT

Scientists like Emily believe that understanding how species are related or separated is an essential part of understanding what action we need to take to conserve and protect them.

“Like many native rodents, the delicate mice play a crucial role in their environment as ecosystem engineers,” says Emily.

Ecosystem engineers are species that change or regulate their environment through their behavior. In the case of the vulnerable mouse, its feeding and digging habits churn up soil and disperse seeds, ensuring the continued growth and health of their ecosystems. But such a large area in Northern Australia is home to vulnerable mice with many different environments and ecosystems.

“The three delicate mice are more specialized in their environment than we previously thought. They are adapted to their unique habitats in northern Australia,” says Emily.

But because the delicate mice have always been considered the same species across Australia, very little work had been done to understand the conservation needs of individual specialist groups.

“Species usually cannot be monitored and protected until they are given formal scientific names. By giving these species their own names, we are taking the first step in ensuring they receive the right conservation attention,” says Emily.

Conservation ecologists can better protect each mouse species and the ecosystems they support by addressing that species’ specific needs rather than treating them all the same.

Perhaps the northern delicate mouse is more affected by land clearing? Perhaps the western delicate mouse has more pressure from feral cats? Maybe the eastern delicate mouse is actually endangered, but we never realized it because it wasn’t its own species?

Whatever the case, identifying, categorizing and understanding nature’s diversity is the basis for protecting it and ensuring Australia’s environment remains healthy and thriving.