The Lizard's Tale 104: The Origin of Anole Species

there are 400 species of animals a classic question on all biologists for evolutionary biologists in general is how do new species arise how did we go from having one species to 400 speciation is the process by which one species splits into two species basically diversification has two parts speciation which is the production of new species and adaptation how species adapt to where they live speciation plus adaptation equals biological diversity in a Knowles we know a lot more about adaptation than we do about how speciation occurs and that's why our current research is focusing on speciation there are many ways to define what a species is and honestly researchers disagree on the precise definition but the one that I favor and the one that's been around the longest is reproductive isolation that means that two species when they come together unable to produce any offspring at all or if they do produce offspring they're infertile a wild example would be a pairing between a walrus and a bird there of course not going to produce any offspring a more nuanced example though is a commonly known one horse and donkey when brought together can produce mules mules are an offspring but they're not fertile they're never able to reproduce therefore donkeys and horses are different species and so when practice speciation is the process by which barriers arise between populations that prevent them from interbreeding there can be lots of different and own species living together in the same forest and so the lizards have a problem how do they tell members of their own species from members of other species they don't want to waste time courting a female of the wrong species or doing battle with a male and those identify members of their own species in two ways one is the dewlap whenever you see species of anoles living together they always differ in their dewlap either the size of the dewlap the color or the pattern learn your gillip colors you can just basically tell which species it is without seeing anything else if you tell me I caught this litter in Puerto Rico and have a red new lab I will say somebody's because you have to say no don't worry I'm sure or if you tell me I caught this an old Porto Rico and it got this do you have that looks sort of drab and brown I said yeah that's the beautiful always go lucky it's a species recognition Seconal that's the idea this is my color on these species similarly be pattern by which they pop their heads up and down when they display to each other summer jiggle-jiggle-jiggle big summer big slow big slow each species has its own pattern and so by looking at the dewlap in the head-bobbing pattern an individual can know whether another lizard is a member of its own species or not a great example comes from two species of the Noles in the dominican republic Anolis i bodis and analyst Marc Noi and if you looked at them from a distance they look identical however when they stick out their dewlap sigh bodis has a white dewlap with a pale yellow wash and Mark Canha white has a very red doula so the dual apps are very different if you put two Sai bodies together they fought like cats and dogs can you put mark hanaway together and they fall but you put a mark an awareness i bodis together and that kind of go stake out their dewlap and that was about it it's like they said Oh wrong species not worried about you then we did this experiment where we change the color of the doula and we did that with the say bodis we pulled out its dewlap and we took red coral lipstick and just smeared the rip lipstick on the doula to make it red like mark aniline and then you put it in with a mark and away and then they fought and you did the same thing to the mark and away you made its do up wider with clown makeup and so changing the color the dewlap did actually fool them into thinking that lizards that weren't their own species really were now what this suggests is that the evolution of the dewlap may play an important role in the speciation process the classic view of speciation has been that it occurs in populations that are isolated physically isolated from one another geographically over time genetic differences accumulate in those isolated populations to the point where if they were to come back into secondary contact they're no longer able to interbreed more recently we've come to understand that adaptation and natural selection play an important role in the evolution of new species one such theory is ecological speciation and that says that adaptation to distinct habitats while populations are in isolation generate the changes that when brought back into contact result in populations being infertile when they pair with one another so the current debate is which of these processes is more important isolation or divergent natural selection right now we're in the midst of a very large experiment to understand the relative importance of the classic model of speciation and the adaptive ecological speciation hypothesis the classic model emphasizes random genetic changes that occur between populations to actually see those changes we need to get genome sequences and compare them between populations so the genome is an important tool in studying speciation an organism's genome is the sum total of all of the genes in that organism and they're responsible for making the organism what it is the anole genome was the first reptile genome to be sequenced it's fairly large it's 2.2 billion bases and in those there are about 18,000 genes that's actually quite similar to the number of genes that humans have our current experiment is set up so that we have a number of populations some of them occur in similar environments but have been isolated for a long time others occur in different environments but haven't been isolated for that long first we'll measure how genetically different they are second we'll measure how ecologically different they are and then third we'll measure the degree to which each pair of populations is reproductively isolated seen if they will mate see if they will lay eggs and if the eggs will will hatch out and produce fertile offspring under the classic model we would expect to find that genetic differences are driving the evolution of reproductive isolation in contrast under the ecological speciation model we expect ecological differences to play a more important role we're still in the middle of this experiment but previous research we've done has shown that populations of the same species that have adapted to different environments do show substantial amounts of reproductive isolation therefore adaptation to new ecological environments can play an important role in how new species arise it's important to study speciation because new adaptations arise but they can only persist and populations are prevented from exchanging genes a lot about what we love about nature is is the diversity of life that exists and speciation is the process by which that diversity is able to be maintained [Music]

Channel: Smithsonian Channel

Views: 28,918

Keywords: reptiles, wildlife, predators, animals, watch, TV online, lizard, Tom Shaner, Costa Rica, Facts, test tube, Tom Schoener, Shane Cambpell-Staton, branch, Jonathan Losos, Documentary, channel, stream TV, survival, biology, caribbean, Hispaniola, Dominican Republic, Law of the Lizards, evolution, characteristic, ecology, video, Puerto Rico, Episodes, free tv, River Anole, science, smithsonian, experiment, free videos, laboratory, ecomorphism

Id: F4PDByWWrKM

Length: 8min 31sec (511 seconds)

Published: Wed Dec 19 2018