WEBVTT - How Do Unrelated Species Develop Similar Traits?

0:00:01.920 --> 0:00:06.960
<v Speaker 1>Welcome to Brainstuff production of iHeart Radio. Hey brain Stuff,

0:00:07.000 --> 0:00:12.559
<v Speaker 1>Lauren bobble bomb here. You may have noticed that although dragonflies, bats,

0:00:12.680 --> 0:00:16.480
<v Speaker 1>and say California condors all have the ability to fly,

0:00:17.000 --> 0:00:20.560
<v Speaker 1>they aren't very similar in any other way. It's not

0:00:20.760 --> 0:00:23.360
<v Speaker 1>very likely that any of these animals had a common

0:00:23.400 --> 0:00:26.720
<v Speaker 1>ancestor any time in the past six million years or so,

0:00:27.120 --> 0:00:30.960
<v Speaker 1>and definitely not one particular shared ancestor that first figured

0:00:30.960 --> 0:00:33.159
<v Speaker 1>out how to haul its body off the ground and

0:00:33.280 --> 0:00:37.080
<v Speaker 1>zoom around in the air. And yet they all developed

0:00:37.120 --> 0:00:41.000
<v Speaker 1>the ability to fly separately. This is an example of

0:00:41.000 --> 0:00:47.159
<v Speaker 1>what scientists call convergent evolution. Evolution doesn't do things on purpose.

0:00:47.360 --> 0:00:49.720
<v Speaker 1>It's not sitting at a big desk in a corner

0:00:49.760 --> 0:00:53.440
<v Speaker 1>office somewhere making decisions about which animals lay eggs or

0:00:53.520 --> 0:00:57.120
<v Speaker 1>get pouches on their tummies. Evolution is the process of

0:00:57.240 --> 0:01:00.560
<v Speaker 1>organisms changing over the course of many generation sans to

0:01:00.720 --> 0:01:04.440
<v Speaker 1>suit the conditions under which they live, and some traits

0:01:04.520 --> 0:01:08.080
<v Speaker 1>like flying, are particularly useful. It can help you catch

0:01:08.120 --> 0:01:11.520
<v Speaker 1>prey or avoid predators, or easily moved to new food

0:01:11.560 --> 0:01:16.240
<v Speaker 1>sources and ecological niches. So it's evolved separately in different

0:01:16.240 --> 0:01:21.200
<v Speaker 1>groups of animals. Several times. However, flying doesn't look the

0:01:21.240 --> 0:01:25.560
<v Speaker 1>same across the groups. For instance, bats developed a membrane

0:01:25.600 --> 0:01:29.479
<v Speaker 1>between their abdomen, arms and fingers to catch air, while

0:01:29.520 --> 0:01:33.720
<v Speaker 1>birds sprouted feathers along a finger fused fore limb, which

0:01:33.920 --> 0:01:37.480
<v Speaker 1>means bats can maneuver their wings separately, while birds have

0:01:37.600 --> 0:01:41.280
<v Speaker 1>to move together. Flying insects just fashioned wings out of

0:01:41.280 --> 0:01:46.520
<v Speaker 1>their exo skeletons. So convergent evolution can tell us a

0:01:46.560 --> 0:01:49.960
<v Speaker 1>lot about what kinds of adaptions work to help species

0:01:49.960 --> 0:01:53.160
<v Speaker 1>survive all the trials and tribulations they might face in

0:01:53.160 --> 0:01:57.240
<v Speaker 1>a particular type of environment, but what ecologists call a biome.

0:01:58.120 --> 0:02:01.680
<v Speaker 1>For instance, in North America, the kangaroo rat lives in

0:02:01.720 --> 0:02:04.840
<v Speaker 1>the Sonoran Desert, where it spends the scorching days in

0:02:04.880 --> 0:02:09.560
<v Speaker 1>a cool, dry burrow and the cool desert nights collecting seeds, vegetation,

0:02:09.760 --> 0:02:13.400
<v Speaker 1>and the occasional insect if they can get it. Everybody

0:02:13.440 --> 0:02:18.359
<v Speaker 1>in the desert wants to eat them coyotes, bobcats, rattlesnakes, owls,

0:02:18.360 --> 0:02:22.280
<v Speaker 1>But the kangaroo rat is fast and agile, with powerful

0:02:22.280 --> 0:02:25.880
<v Speaker 1>back legs and extremely sensitive hearing, all of which helps

0:02:25.880 --> 0:02:28.959
<v Speaker 1>it survive a hard scrabble bottom of the food chain.

0:02:29.080 --> 0:02:33.960
<v Speaker 1>Desert biome lifestyle, and although the kangaroo rat doesn't have

0:02:34.080 --> 0:02:38.960
<v Speaker 1>an enviable life, it is effective to other rodents on Earth.

0:02:39.400 --> 0:02:42.800
<v Speaker 1>The Australian hopping mouse in the Australian Outback and a

0:02:42.840 --> 0:02:45.720
<v Speaker 1>species called the jerboah in the deserts of North Africa,

0:02:45.880 --> 0:02:50.600
<v Speaker 1>Asia and the Middle East evolved separately and yet incredibly similarly.

0:02:52.360 --> 0:02:56.720
<v Speaker 1>But how does convergent evolution happen? This is a trickier question,

0:02:57.080 --> 0:02:59.600
<v Speaker 1>and the development of genetic tools over the past twenty

0:02:59.680 --> 0:03:02.880
<v Speaker 1>years has been helpful in picking it apart. In a

0:03:02.919 --> 0:03:06.080
<v Speaker 1>twenty nineteen study published in the journal Science, a group

0:03:06.120 --> 0:03:09.240
<v Speaker 1>of researchers at Harvard University looked at the development of

0:03:09.280 --> 0:03:13.200
<v Speaker 1>flightlessness and birds, a trait that's evolved several times over,

0:03:13.760 --> 0:03:17.480
<v Speaker 1>and exactly how evolution pulled it off in penguins in

0:03:17.520 --> 0:03:21.840
<v Speaker 1>the same way that it did in ostriches. Flightless birds

0:03:21.960 --> 0:03:26.240
<v Speaker 1>or rattites can't fly for a couple of reasons. Somewhere

0:03:26.280 --> 0:03:29.760
<v Speaker 1>along their lineage, they have lost their keel, the bone

0:03:29.800 --> 0:03:32.880
<v Speaker 1>that runs perpendicular to the breastbone on flying birds that

0:03:32.960 --> 0:03:37.440
<v Speaker 1>the pictorial muscles attached to, and they have reduced four

0:03:37.520 --> 0:03:41.200
<v Speaker 1>limbs arranging from nearly absent in the Kiwi bird, to

0:03:41.520 --> 0:03:46.120
<v Speaker 1>still obvious but reduced in size in the ostrich However,

0:03:46.560 --> 0:03:50.200
<v Speaker 1>there are many ways the particular convergent traits can evolve.

0:03:51.320 --> 0:03:55.080
<v Speaker 1>We spoke with Tim Sackton, director of bionformatics at Harvard.

0:03:55.760 --> 0:03:59.560
<v Speaker 1>He said, before genomics, one could use developmental tools to

0:03:59.640 --> 0:04:03.240
<v Speaker 1>figure out if the same or different developmental mechanisms seemed

0:04:03.280 --> 0:04:07.240
<v Speaker 1>to be involved in convergent phenotypes. But the idea of

0:04:07.400 --> 0:04:11.440
<v Speaker 1>levels of convergence same mutation, same gene or same pathway

0:04:11.840 --> 0:04:15.000
<v Speaker 1>has developed in large part because it's possible to look

0:04:15.080 --> 0:04:18.360
<v Speaker 1>in the genome for these things now. In the rabbites,

0:04:18.440 --> 0:04:20.960
<v Speaker 1>for example, we were able to show that the same

0:04:21.120 --> 0:04:24.600
<v Speaker 1>regions of the genome the control where and when certain

0:04:24.640 --> 0:04:29.279
<v Speaker 1>genes are expressed, are repeatedly evolving in flightless birds. But

0:04:29.440 --> 0:04:35.719
<v Speaker 1>this doesn't seem to involve the same nucleotide mutations. And yes,

0:04:35.760 --> 0:04:39.080
<v Speaker 1>where some traits converge from completely different corners of the

0:04:39.120 --> 0:04:43.839
<v Speaker 1>living world, the opposite is also true. Divergent evolution is

0:04:43.880 --> 0:04:47.360
<v Speaker 1>the process by which groups from one species or organism

0:04:47.400 --> 0:04:51.680
<v Speaker 1>begin to develop different traits, thereby splitting in two separate species.

0:04:52.440 --> 0:04:56.680
<v Speaker 1>This often happens when populations of a species are separated geographically,

0:04:57.120 --> 0:04:59.760
<v Speaker 1>and over time they adapt to the conditions of their

0:04:59.800 --> 0:05:03.600
<v Speaker 1>new spot, whether it's increased predation pressures or a change

0:05:03.600 --> 0:05:08.480
<v Speaker 1>in climate. One famous example of divergent evolution was found

0:05:08.520 --> 0:05:11.600
<v Speaker 1>by Charles Darwin and has travels to the Galapagos Islands

0:05:11.600 --> 0:05:15.280
<v Speaker 1>in eight thirty six. Darwin's finches, as they're now known,

0:05:15.520 --> 0:05:18.240
<v Speaker 1>were a group of tanagers, which are not true finches,

0:05:18.520 --> 0:05:21.880
<v Speaker 1>that lived on different islands in the archipelago, the main

0:05:21.920 --> 0:05:25.239
<v Speaker 1>difference between them being the shape of their beaks, which

0:05:25.320 --> 0:05:28.720
<v Speaker 1>changed over the generations due to the particular foods available

0:05:28.760 --> 0:05:33.240
<v Speaker 1>to the birds on the different islands. And one more

0:05:33.279 --> 0:05:38.839
<v Speaker 1>example fingerprints. Most non human animals don't have them, except

0:05:38.880 --> 0:05:42.719
<v Speaker 1>for close human relatives such as chimps and gorillas, but

0:05:43.120 --> 0:05:47.640
<v Speaker 1>koalas have fingerprints to The fascinating thing about human and

0:05:47.680 --> 0:05:51.360
<v Speaker 1>koala prints is that, even though they're almost identical, they

0:05:51.360 --> 0:06:00.080
<v Speaker 1>seem to have evolved independently. Today's episode was written by

0:06:00.160 --> 0:06:02.920
<v Speaker 1>Jescelin Shields and produced by Tyler Clang. For more on

0:06:03.000 --> 0:06:06.360
<v Speaker 1>this and lots of other converging and diverging topics, visit

0:06:06.400 --> 0:06:08.960
<v Speaker 1>how stuff works dot com. Brain Stuff is a production

0:06:09.000 --> 0:06:11.520
<v Speaker 1>of iHeart Radio or more podcasts in my heart Radio,

0:06:11.720 --> 0:06:14.479
<v Speaker 1>visit the iHeart Radio app, Apple podcasts, or wherever you

0:06:14.520 --> 0:06:15.800
<v Speaker 1>listen to your favorite shows.