|What is the relation between continental drift and the evolution? How four very different kinds of ant/termite eaters could occur in India, Africa, South America, and Australia?|
|Question Date: 2019-10-31|
It is weird to think of entire continents changing and moving, isn’t it?
Let’s start off with how new species evolve. It probably happens most often when members of the same population get separated from each other. When they can’t interbreed anymore, each one goes down its own evolutionary path. Different random changes will happen in each population due to random mutation. Some of those changes will be beneficial, or at least not bad, and spread in one of the populations. The same change may never happen in the other population. Or if the same mutation does happen, it may die out because it doesn’t give an advantage. Maybe the mutation is good in dry habitats, but only one of the populations has a lot of dry habitats, for example. After a while, the populations may become so different, that they can’t interbreed anymore and become new species. If one continent drifts away from another, this kind of isolation can happen.
Continents can also become connected. This might bring together species that haven’t been separated so long that they can’t interbreed. They may be able to mate and create “hybrids.” For example, bison and cows can interbreed and have “beefalo” offspring. Tigers and lions in zoos have been bred to create tigons and ligers. It’s not just mammals that can form hybrids, but you might be more familiar with those examples.
Why do you think there are many more kinds of ants than there are ant eaters?
Thanks for asking,
First, a point of clarification: when Alfred Wegener proposed the continental drift hypothesis, he was not incorrect, but he failed to provide an explanation for HOW continental drift would occur. Enter plate tectonic theory - it was based off of Wegener's idea, but was able to demonstrate that continents have been moving around for almost all of Earth's history (and have come together and broken apart several times) because heat from the Earth's core drives movement in the mantle (it's solid, but is ductile - so it can move slowly), and the plates of lithosphere ride around on top of the moving mantle. Plate tectonic theory has been widely accepted by scientists since the 1960s.
The answer to your specific question is that there is no relationship between plate tectonics and the four different groups of "anteaters" that live on different continents, but look similar. This actually happens due to "convergent evolution" - the independent evolution of similar features in different species that live in different places/points in time.
The environment in which these groups of animals live have large mounds, filled with insects (like ants, termites, or other colonial insects) that make a delicious meal for a mammal. So, these "anteaters" evolved long claws to dig into the mounds, and sticky tongues to pull the insects out. Because the same conditions were present at different points in space-time, animals evolved in response, and ended up being really, really similar to one another. True anteaters live in S. America, pangolins are found in India & Africa, the aardvark is found in Africa, and the numbat is found in Australia. There are other, non-"anteater" animals who have evolved similarly too - such as the Indian Sloth Bear (currently living), and Fruitafossor (an extinct mammal that was alive during the Late Jurassic - yes, it DID live alongside the dinosaurs).
Continental drift causes species to evolve away from each other (called divergent evolution) by separating them so that individuals on one continent cannot breed with individuals on another. When many individuals in a population can interact with each other, their offspring could have any combination of genes that are represented in that population, but if the population is separated into two or more groups, then the next generation in one group can only have the genes available in that smaller group, which will not be the same as the genes in the other group. How each population evolves depends on what individuals it starts out with.
Also, when two initially similar populations end up in different parts of the world, they will be living under different environmental conditions. Animals or plants with the traits they need to survive on the continent where they live will be the ones that are able to survive and pass on their genes. On a different continent, they need different traits, so the animals or plants that survive there will be different from their distant relatives on the other continent.
What you are talking about is called convergent evolution, which has nothing to do with continental drift. The animals that evolved in these four continents did so independently.
Mammals evolved late in evolution, after continental drift had broken up the earliest and biggest continents. Therefore the ancestors of the anteaters on the different continents are very ancient. The anteaters on the different continents are only distantly related to each other.
Here's a link for how fossils provided evidence for continental drift: ScienceLine
I like the first slide in this powerpoint presentation - it shows when the oldest super-continents broke up and produced the continents of today. The continents have moved a lot since the dinosaurs became extinct 65 million years ago. Mammals mostly evolved after dinosaurs became extinct.
Continental drift occurs because of plate tectonics - huge rocky plates on the earth's surface move around. Prof. Tanya Atwater at UCSB is famous for her work on this.
Continental drift allowed for the isolation of the same species in very different environments, leading to different paths of evolutionary adaptations that, over long periods of time, created a number of different species. When all of the continents were together, it was possible for a single land species to be present across vast areas that are now different continents. With continental drift though, populations of that species become isolated on each of the land masses it lives on. Over time, as it adapts to the different environments that it experiences, the single species can branch off, becoming multiple different species with the same origin.
That's why there are very different kinds of ant/termite eaters across very different continents: they have a common ancestor that was present across a wider range but with continental drift, each population evolved separately, become very different.
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