What is evolution? – Behind The News

Cale Matthews, BTN Reporter: The diversity of life on Earth is amazing. Millions of species grow, flower, fly and scurry across the planet. So where did all that feathers, fur and fins come from?

Sorry, it’s just me, but I thought this story could use some David Attenborough voiceover. Anyway, let’s see for ourselves.

Hi Rachel

Dr Rachael King, Senior Researcher at the SA Museum: Hello

There are so many different animals on Earth. Some are microscopic, some are as large as elephants. What is a species?

Dr. Rachael King: That’s a great question. We have a whole scientific system for classifying living things. It’s called taxonomy, and in that classification, the smallest, most detailed part is the species.

The definition of what constitutes a species is a bit complicated, and there is sometimes disagreement about which species an organism belongs to, but essentially it is a group of organisms that can reproduce (i.e. have babies), share common features that make them look similar, and share most of their DNA.

Dr. Rachael King: Most often these days, we look at DNA. Sometimes when you look at bodies, that’s what we call subjective. So I might have a different view of what something looks like than you might look at something, but DNA is a very clear scientific method that can be used to study how things are related.

Okay, that’s the genre, but I still have a few questions.

Steve, I think I know what a genre is now, but there are clearly a lot of them. So where did all those genres come from?

Prof. Steve Cooper, Principal Researcher at the South African Museum: This extraordinary diversity of species has arisen through the process of evolution.

The idea of ​​evolution has been around for a long time. In the 18th century, a guy called Jean Baptiste Lamarck theorized that it was because animals changed over the course of their lives. So a giraffe that would stretch its head to reach leaves high up in the branches would lengthen the bones and muscles in its neck, and then pass those changes on to its children. And that’s how we ended up with so many different-looking animals and plants. He was right about a little bit, but not entirely. About 50 years later, Charles Darwin and Alfred Russel Wallace came up with the theory of natural selection. They figured that within a population of animals, each individual is slightly different, and some of those differences mean that the animal will be better at surviving in its particular environment. For example, a slightly thinner beak makes it easier to pick up insects, a slightly stronger beak makes it easier to crack open nuts, or a slightly longer neck makes it easier to eat hard-to-reach leaves. So those animals are more likely to eat and survive, and also to have offspring with thinner beaks or strong beaks or long necks for a really long time. These small changes can turn out to be big changes in a population and give rise to entirely new species.

Prof. Steve Cooper: Let’s take an animal that moves into a cave. If it has the ability to sense its environment much better, it’s going to be better adapted. It’s going to find its food, it’s going to survive, it’s going to reproduce. Evolution is incremental changes in DNA over time, and through that adaptation to a new environment, it can evolve into new species.

Okay, I think I understand the process, but I’d like to know how a species actually gets its name so I can find someone.

Ben! How are you?

Dr Ben Parslow, SA Museum Collections Manager: Alright Cale! Welcome.

Thank you, I just learned how species evolve. But how does a species become a species?

Dr. Ben Parslow: Well, for a species to actually become an official species, it has to be formally described. So there’s a complete process that we use to do that. The first thing we have to do is actually discover those species. You can do that by collecting them in the field, in the environment, or actually finding specimens that are kept in natural history collections like museums. Then we examine the material thoroughly and carefully, and then we check its identity, so we compare it to all the known species to make sure it’s different, and then we have to prepare a species description. So we write a really detailed description that describes all of its morphological features. We have images of the specimen. Often we also include DNA data, and then we submit it to a scientific journal where other experts review that species description and then approve it as a new species. So from that point on, you have a new species.

Now, Ben, I’m looking at the specimens here, and some of them are in red boxes. Is that something special?

Dr. Ben Parslow: So in our collection these red unit trays, these boxes actually represent type specimens and holotype specimens.

The holotype is essentially a reference point for the entire species, so it’s the original specimen from which the species was first described. And museums and universities around the world will have holotypes as reference points

Dr. Ben Parslow: And it allows our future researchers to come back and study this species. But I have something I can show you. So let’s move on to another part of the collection.

Okay, let’s do this.

Dr. Ben Parslow: And here’s a specimen.

Here’s a specimen. Ben, I think I know what this is, but could you explain?

Dr. Ben Parslow: This is the holotype specimen of a species of wasp that you collected. It’s the only specimen of that species ever collected.

There you have it. It even has my name on it. Does that mean I can just put it in my pocket and go?

Dr. Ben Parslow: Well, we’ll actually leave it in the museum and look after it, but it’ll stay here so other scientists can look at it and study it and compare it to other species.

Are we still describing and discovering new species?

Dr. Ben Parslow: All the time. So although we’ve described about 1.2 million species worldwide, it’s estimated that there are about 8.7 million species in total. That means there’s still a lot of things to discover, even in groups that are relatively well-studied, like mammals and birds, new techniques that allow us to look at their DNA or study their populations have allowed us to actually discover new species there.

Yes, new species are being discovered all the time, and I’m not the only one. And that can be a job for museums like the SA Museum, which has over 3 million specimens in its collection, to preserve the record of life on Earth.

Dr Andrea Crowther, Senior Collections Manager SA Museum: This is a grasshopper specimen collected from Kangaroo Island in 2023. It’s significant because in 2019 Kangaroo Island had extensive bushfires across the island. Museum staff went back in 2023 and surveyed the fire-sensitive areas and this is one of the specimens they found in that area. So we know if there are going to be fires in the future and if they devastate those areas, we know what happened there.

It’s a bit like taking an inventory of the different species that exist in a given place, and having them in a museum, we know which ones existed and where?

Dr. Andrea Crowther: Absolutely. This record will never be lost, and people will be able to go back and study the specimens, even if they are no longer on the island.

Well, I think I’ve learned enough now that I’ll be able to go to bed one day.