>> a male blue bird of paradise is advertisingfor a mate. it's quite a performance but he's not the only bird of paradise here. keen tomake an impression. there are nearly 40 different kinds on the island of new guinea, each witha display seemingly more bizarre from the rest. (bird calling) a rightful bird of paradise.like many jungle animals, birds of paradise avoid competing with each other. these doso by living in different parts of this jungle
how much do garter snakes cost, of an island. the sixth pruned birds of paradisedisplays in his special caring on the forest floor. (bird calling continues) the magnificentbird of paradise favors the low branches of bushes. his female is modestly dressed. themale has a good set of lungs, but he'll have to do more than flutter his eye lids if hewants to impress her. it will all depend on
his performance. the females may be dull lookingbut they're very picky. and it's time for a really close inspection. his right sidelooks fine, but what about his left? pretty impressive, but is he magnificent enough?oh, dear. her departure says it all. generations of choosy females have driven the evolutionof these remarkable displays. the more extravagant a male is the more likely he'll be noticed.(bird sounds) >> professor shabel: tell me if you guys haveany trouble hearing me. just wave in the back if you ever have trouble hearing me. and whenyou guys ask questions if you could try to speak up. that was a request that was madeas well, just to try and speak loudly with questions. questions are welcomed. interruptanytime. i tend to just buzz through these
slides, right. so interrupt me if you wantto ask something. feel free. carrying on today with some material i didn't get to last time.i'm not quite caught up but hopefully after the next couple of lectures i'll get caughtup. finishing with a discussion of sexual selection, you just saw that video of sexualselection in some birds of paradise, and some cool examples of coevolution as a way to introducespecies concepts and the question of questions, speciation and the origin of new species,the one major question that darwin and others were wrestling with. and the mechanisms ofspeciation we'll look at today at the end. we won't get to all of them, but we'll startto discuss the differences in allopatric and sympatric speciation, major mechanisms ofspeciation that are thought to drive the process
in plants and animals. sexual selections leadsto some bizarre forms in organisms and this was a topic of discussion around darwin'stime because in the origin he didn't address this in detail. he would later write a wholebook on sexual selection. it seem to provide a contradiction to natural selection. whenyou see organisms in nature, for example, peacocks with the ridiculous spray of feathersand all these shimmering eyes that exist on these feathers that they used to attract peahens,but at the same time that things are good at attracting peahens, there also good atattracting predators, right and they slow the bird down. it's a big heavy apparatusthat's highly visible and slows the bird down so wouldn't attract predators and therebylead to increased mortality and reduce reproductive
output? darwin couched this discussion inthe context of sexual selection and the increased reproductive output that this male might experienceas a result of being attractive to females, so any negative from exposure to predatorswould be counter balanced and exceeded by the positives associated in their fitnessin relation to females. and that's the general contours of the way that debate was framedearly on about the role of sexual selection in these processes. sexual selection can beconsidered a category under natural selection if you want. it's sort just a semantic issuereally whether you think the sexual selection as a distinct type of selection or somethingunder natural selection. in my opinion it doesn't matter too much about how you categorizeit, but the important of importance of it
is quite real 'cause you see this all overthe natural world. now selection can occur between the sexes as i was describing withthe attraction of the female peahen, it's an attraction of the female to the male betweenthe sexes, intersexual selection but you also have situations of intrasexual selection wherethe sexes compete for access to mates. and there are great examples of that among malesin, for example, our friendly elephant seals, the local elephant seals that i described,that i describe **sound distorted beginning here (inaudible) these bull elephants, youcan you see them right now in the coast just within an hour's drive. the males are huge.in comparison to females they are big and the males enter these great battles. theseare southern elephant seals (inaudible) to
our local elephant seals with the same ideaand you will see the types of battles they engage in and these things last battles sometimesfor hours. so that's a really big male on the left and somewhat smaller on the right.but that's not friendly competition there. the young animals will engage in the sparringmatches and practicing for later for more serious bouts but they're really digging in.they have teeth that they'll try to slash their opponent with. they develop a shieldon their chest, a thickened layer of skin that effects that functions as a shield againstthese attacks. it's exhausting but they get bloody, these shields get bloody, they getexhausted. the male on the right is trying to defend this beach because that's a beachthat occupies and defends to protect its harem
because there's a bunch of females on thebeach that are defended by this male.**distortion ends herethe beach itself is a breeding ground and females need access to breeding grounds. thenumbers of suitable breathing grounds, the number of beaches that are relatively wellprotected for the seals are limited. so space is limited and the females need access tothis spacial resources. so males defend the spaces against other males. so one male canbe one big bull male can be the occupant of a beach and defend it against all incomingmales and the males, the big males hang off shore and wait sometimes weeks sometimes evenacross the years for opportunities to come in and try to bully the other male off thebeach to gain access to that whole harem.
and it leads to major differences in the sexesin fitness and reproductive success. so when you look at data like these, you can see herethe number of offspring that the individuals have on the xaxis. it says number of offspringweaned. weaned just means successfully raised, post feeding with milk that the offspringgoes off and is successful. so number of offspring weaned or number of offspring produced here.and the percentage of the males and the percentage of the females that produce that many offspringas shown on the xaxis here. i'm going to try and get a better modality for okay, so 0 to10 offspring for the females, how many what percentage of females produce no successfuloffspring during their lifetime? well, it's upwards. sixty or more percent don't succeedin producing any successful offspring just
because it's a dangerous world offshore withthe sharks and killer whales and all the possible sources of mortality for the young, so therearen't just that many there aren't many young produced for any female. most of the successivefemales are producing one, two or three offspring, a relatively high percentage when you addup those numbers, are producing a few offspring. and a smaller number of females are producingup to 10 offspring during their course of their lives. but look at the males by contrast.a different scale here on the xaxis running all the way up to a hundred offspring as opposedto 10 for the females. most of males are not producing any, even a higher percentage ofthe males than the females are producing no offspring at all and no successful offspring.but a small number of males are producing
a whole lot of individual offspring with somemales producing up to over 80 offspring, so the majority of the reproductive output isheld by a very few number of individual males where it's more balanced in the females soa very different world in which the two sexes are living here, very different sources ofcompetitive interactions that influence both and has effects on their morphology. the bigbull elephant is as long as from here to the wall. they are gigantic and you can go walkamong them at ano nuevo on the on the beach there if you set up appointment there witha docent, call the natural park there and set up an appointment. i don't know if they'restill available this season, but they'll walk you right among them and it's very excitingbecause you go around one of these dunes and
there might be a big bull there that decidesto charge. now they're not very fast so you can scurry away, but there's always that sourceof excitement when you're hiking out there that you might get charged by a big bull.elephant, they don't use the hind legs so they kind of inch worm, but they're giganticand that's exciting. and that influences their morphology. not only only are they huge, butthey have the big nose. they have the chest shield. they differ in the way they look fromthe females, and traits that, um, that's in, that's in the case of entrust sexual selection.you get those differences in traits, or the massive horns of certain ungulates, like wesaw a couple of rams up there earlier on a slide that those are similarly derived traitsin the males for doing battles. if you look
at intersexual selection and the types oftraits that might develop to attract females you'd refer to those as epigamic traits, traitsthat are selected by the opposite sex for some aspect of reproduction and the lizardslike these anoles are familiar if you've gone to tropical habitats, because they'll be perchedon a small branch and they'll throw out their dulap, this structure that's often colorfuland they'll do pushups and they'll make themselves look really showy in an attempt to attractfemales and meanwhile they're attracting birds of prey and other organisms that might perdate upon them but counter balanced again by the success they're having in attractingfemales in their reproductive output. birds going to great great lengths as you saw inthe video before lecture of the bird, of the
birds and their and crazy dances that they'llgo through to attract females. or bowerbirds like this building these very elaborate nests.this one has collected, i think, a bunch plastic objects that it finds attractive or it hopeswill be attractive to a female so it's decorated its bower for these females in hopes of attractingthem. the females are supposed to walk through and investigate this whole apparatus and decidewhether it wants to stay and mate with that male. here is another bower, all these shelvesare deemed attractive and it's decorated with all these empty shells. it's incred it's costthat's very costly. it's spending a lot of its days building these things and exposingitself to trouble in the process of elaborately building these nests. why are the males doingthat and not so much the females? why is it
that the females are the ones investigating,nitpicking and being choosy about which males to mate with in these systems and others systemslike this? why is it females that are usually choosing? >> female student: maybe strength. >> professor: in what sense? she said maybeit's strength. >> female student: (inaudible) >> professor: okay. so somehow related tothe physical strength of the organisms. the males are often larger and often strongerin these systems, and so the females are looking for the ones that appear to be strongest andmight give their offspring the biggest, the
greatest chance of survival. good. we'll lookat some evidence behind something like that in a second. yeah, that comes into play. oneback here. go ahead. >> student: (inaudible) >> professor: from a biological perspectivefemales invest more time and energy in there offspring. and thus? >> male student: (inaudible) >> professor: and thus this their selectionpressure exists for them to be choosy because they can't afford to make a mistake. any elaborationson that point or other points? >> female student: females produce (inaudible)
>> professor: females produce what? >> female student: fewer gametes. >> professor shabel: fewer gametes. fewergametes, but larger and more expensive gametes and that's what's illustrated here and knownas the phenomenon of anisogamete. eggs are just bigger and more energetically rich andexpensive than sperm. and that goes that has deep roots, so eggs are more costly to produceand then as you indicated it doesn't just stop there because in the case of the birds,for example, it's the female that develops the embryo in her own body and that's expensive,just the production the egg, the unfertilized egg is expensive relative to sperm and thenthe growing of that egg once fertilized into
the young animal is extremely expensive andheavy and then the baby is born in the case of the bird or the mammal and usually it'sthe female that's responsible for feeding it whether it's from milk or from catchinginsects. sometimes the male's not involved at all. so costly again for the female atthat stage, so the costs all along tend to be greater for the females in these systemsand, thus, the females needs to be careful about the investment that she makes in termsof the male contribution. that's the logic. and the female should choose a male that'sgoing to be providing a genetic contribution that's successful in the local environmentaccording to the darwinian terms, so example of that, (frog noises) so that is a frogscalling. frogs are calling right now. i heard
them last night in berkeley. it's warmingup. it's still damp out so the little local coarse frogs are starting to call in the park.this is another type of related frog to the one we have locally and they call like that.then are they they you've all seen it, at least in a video like this. the males aredoing that. the females are not calling. it's the male's calling. and some males call moreloudly than other males or for a longer periods of time. according to a good gene hypothesisthe strength of the production relates to the fitness of those genes for the local environmentby the one who's making those productions. and this is along the lines of what you weresaying about the strength of the male, i think. the good genes hypothesis which i just explainedin a poor way, i think. the good hypothesis
suggests that males are honest in the displaythey're making reflecting the fitness of their genes for the local environment. so a malethat calls for a long time and loudly would indicate strength for the lineage, and thefemale should be selected them if they're not being deceitful. so a test of the goodgenes hypothesis in frogs was made in an elegant way, and this study where long calling frogsand short calling frogs had their sperm extracted and taken and used to fertilize the eggs ofa single female frog. so the eggs of this female were split and half of them were allowedto fertilize with a long calling male and half of them were allowed to fertilize witha short calling male and the offspring were followed. the offspring of the short callingfather, and offspring of the long calling
father were followed through time, and fitnessof their offspring was tracked over time. here's a table that shows some data. now thedata are too few and more data are needed but it was suggested by watching the growthof the larvae that developed from the fertilized eggs and survival of those larvae and howlong it took it took for those larvae to develop to the adult frogs, there were clear indicationsthat in a couple of those categories, that the long calling frogs offspring were moresuccessful in these terms. so this providing support for a good genes hypothesis in a nicecontrolled study. more studies like that are needed to test hypotheses like these. it'sdifficult to get certainly in birds or mammals. easier in an amphibia like this where youcan have more control. a brief **coevolution
here. coevolution, i don't think i definedit on a slide, but think it of as a changes in adaptation of organisms in relation toanother organism, so coevolving organisms, coevolving species adapt to one another throughtime in measurable ways. darwin knew of this flower that grew in madagascar and its floralstructures suggested the existence of a pollinator with an extremely long proboscis that wouldbe allowed would be able to access the nectar and served to pollinate the flower. so uponseeing this flower darwin predicted the existence of an organism which wasn't known at the time,and it wasn't until after his death that this this moth was discovered that had the verylong proboscis that was observed to pollinate this flower. he was making an inference basedon coevolution, based on the morphology of
the flower for a coevolved pollinator. andit was it, it highlighted for people of the power of the argument in predicted somethingthat wasn't known to exist and then it exists. that's that's astonishing to people who haveno exposure to the predictive potential of biology. it said in motion many of these studiesof coevolution, and we have a great one right here in the berkeley hills another drama playingout right here now, and if you haven't seen these creatures try to schedule a hike inthe next couple of weeks because they're out in numbers now, these newts. i can give yousome suggestions about where to go especially if you have a car. you can go see them bythe thousands, but you can also see them up in the botanic garden, the u.c. botanic gardenhas newts in its ponds usually, although numbers
are declining in recent years according tothe director there. they're still up there though. it's a crea it's an amazing creature.this is one of the species. we have two species locally. this is taricha granulosa. there'sanother species. taricha is the genous. they are called newts. they are amphibians relatedto frogs, right. this is one in an unken reflex, unken, unken reflex. it's displaying its colorfulbelly and curling it's tail to display the orange under its tail in contrast with thedark upper portions of the body to make itself visible. it's not trying to hide here. it'strying to make itself visible. it's aposematic. i'll just spell that on the board here. aposematic,aposematic. it's a warning to would be predators that they would be making a mistake shouldthey try to attack or eat this creature, and
the ones that do eat them are these gartersnakes. the local garter snake preys upon them. these things are extremely toxic, thelocal newts. now you can go have fun and look for them and even hold them and not worryabout any harm, but don't put them in the mouth and don't play the silly game and lickthem because you've heard that they are dangerous and want to test the notion. they are dangerous,trust us. they will kill you. the toxin in one of these animals could kill a bunch ofus. but just my holding them you don't have any problems. it has to get into your mouthand you won't do that, right. tetrodotoxin is the toxin that they are using for defense.it's the same toxin that puffer fish and some octopuses have in their systems to defendthemselves. it's a neurotoxin and is very
effective, but the garden snakes have developedimmunity to a degree to that toxin over the millennia who knows how long? we don't havegood estimates of that the garden snakes developed immunity and the newts have become more toxic.in response the garter snakes have developed greater immunity and the newts have becomemore toxic and that's this arm's race, this coevolutionary arms race that has lead toa hypertoxic newt that's way more toxic than it needs to be for most predators. an owleats one and it will die. i was a graduate student in this department who found an owlonce dead, dissected and found a newt in the belly and made the connection that it atea newt and it died. so this is and example of coevolution in this local case. it's aworld famous case and it plays out in the
berkeley hills. it plays out in the east bayand a bit more broadly down towards santa cruz county but it's really a local phenomenon,this arm's race. it gets better when you look at this third member of the system a localsalamander that looks a lot like the newt. the first time you go out, if you saw thisthing, you'd think it's a newt. people call them newts all the time. they're not newts.they're also amphibians, but they're not closely related to newts. they have those groovesdown their side. you'll start to see that if you look at them. they have a sort of aconstriction at the base of the tail. they kind of walk taller than a newt. well, thisis a salamander called ensatina. it's convergent on the newt. why? why does this think looklike a newt?
>> professor: yes, exactly. it quote unquote,she used air quotes there to say it knows that the newt is poisonous, which is an appropriateuse of air quotes because it doesn't necessarily conscientious know that the newt is poisonous;but it has evolved to look like the newt to benefit from the warning coloration that thenewt has to illustrate its toxicity. well, the ensatina salamander is also flashing thatcoloration. you can see the comparison; dark above, orange below in the newt. the newt,you can't see its eye here. but it even has a little yellow strip on the top of its eyeand the salamander also has that right down to the details of the eye ball. it has theyellow on top of the eye, it's local ensatina does, dark above, orange below. it's verysimilar, so it's mimicking the newt, right.
you don't want to eat salamanders either.they're just all� all most salamanders are have a small amount of toxicity. don't eatthose either, but they're nothing like the newt. in the context of mimicry you have thesetwo types which it wouldn't be bio 1b if you weren't introduced to batesian and mullerianand mimicry. so these are based on these two guys who were studying in the amazon in the1800s and had discovered this phenomenon where organisms will mimic another organism to benefitthemselves. bates was the first to work on this and he was looking in the context ofbutterflies that themselves were not distasteful, but they were mimicking butterflies that weredistasteful. and it became known as batesian mimicry or batesian mimicry. muller from germanywas also there, but he found some butterflies
that were mimicking, that were distastefulor harmful mimicking other ones that were distasteful or harmful. so you have an honestcase of mimicry and a dishonest case of mimicry, if you want. and what is the local salamanderdoing in relation to the newt. most people consider it a type of batesian mimicry 'causethe the salamanders, in fact, harmless, although, as i described is vaguely poisonous. so somepeople, still sort of a minor debate as to whether you call the local salamander a batesianmimicry or a mullerian mimic. common phenomenon in nature, and this is all in the contextof natural selection, right. selection is the hypothesis for the driving of all of theseadaptive changes in the natural world, the only force among the forces of microevolutionwe looked at that creates adaptive change
of this nature. genetic drift is not thoughtto be capable to leading to such a change. we need to finally ask ourselves what is aspecies, because we've been using the word a lot. if you go through a biology lectureor a biology textbook species is one of the most commonly used words in the biologicallexicon, and yet no one can agree on what a species is. there's some 20 definitionspublished of what a species is. i'm going to look at only three in the course of thenext couple lectures. you have a general understanding of what a species is and it tends to be amorphological concept. you go outside and you see a big black bird flying in the skyand you say crow; and you see a little bird on the ground that's brown and nondescriptand you say a sparrow. and you know they're
different because they look different andthey fly differently. there's a tree of one type and a shrub of another type, and theyare all different species. they're different natural kinds of things. that's a traditionalway of relating to these organisms and safe enough, good for for our basic interactionswith the world, but as you dissect the definitions you see how you learn how complex it is. we'llalso look at the biological species concept which is one that if you ask a young biologystudent what is a species, they'll tend to recount a biological concept. so we'll lookat that in some detail and we'll move toward phylogenetic species concept. next week inlab you are starting phylogenetic analysis and you'll have two weeks of lab that focuson phylogenetics and we'll need a new concept
to help us in that context. as a result ofinadequacies of these traditional concepts. morphological concept; well, what are someof the problems with a morphological concepts? you have a bunch of horses here running freelyacross the planes. it's pharrell horses probably. they all kind of look different, right. spotty,white with brown spots, beige, tan, big and dark, light and dark, large. well, are theseall different species? of course not. it's just a horse. there's morphological variationamong the individuals, but not sufficient by some criterion to establish them as differentspecies on morphological grounds. they just vary in their patterning. there are many,many examples of this, and sometimes it has a fooled biologists over time especially inhighly variable widely geographically distributed
organisms like snakes like these. these cornsnakes look quite different over there distribution in the united states. it's more of a superficialdifference though. when you look more deeply you can see the common underlying patternsthat are overlaying by the more showy colorful patterns. it's all one species of snake. byany of our concepts, this is one species of a snake, and you can't naively apply a morphologicalconcept to it. it has full biologists. butterflies like these can respond to environmental queuesand be influenced by the environment during their growth to look different as of as adults.it's not genetic variation here. it's just phenotypic plasticity in relation to environmentalqueues that lead to different in differences in the adult form. yes?
>> professor: do you have to look more alongthe terms of macroevolution to describe something like this you're saying? >> professor: i i'm sorry. i'm having troublehearing you. >> professor shabel: it's and we can discussmore afterwards. i'm having trouble hearing it a little bit, but i think you're sayingwouldn't this constitute an evolutionary adaptation in itself. well, it depends. this could justbe driven by chemical queues that have no relationship to the environment in an adaptivecontext. there might be no adaptive explanation for these differences in color could simpcould simply be a byproduct of different chemistry in the environments and in their foods. soyou'd have to dig into the system a little
more to know whether to call this adaptivebut let's, let's discuss it more. you have some good ideas there. maybe this is a betterexample. where you had adult butterflies that look like this, of a couple different kindsand they were considered a single species 'cause they kind of look all like this, butbiologists had a suspicion based on behavioral differences that you were dealing with a coupleof different types. it wasn't until the larvae were studied and found were found and studiedin detail that it was seen how different the larvae were in terms of how they looked; spotsversus stripes and the microhabitat associations, the ecology the different between the twolarvae that showed the adults were monomorphic, but larvae were quite different signallingtwo different species that just happened to
look like, alike as adults. so partly as aresult of the problems with the morphological concept when you get into the subtleties ofthese organisms, the biological species concept was advanced and became prominent. ernst mayrwas a very famous biologist of the last century, one of the architects of modern synthesis.an ornithologists, someone who studies birds, the german who worked in the, in the old worldtropics, and he articulated and defended, with great success, a biological species concept.and this is the one, as i said, you probably will be familiar with from basic biology.a definition; something like a species is a population whose members have the potentialto interbreed in nature and produce viable fertile offspring. so it's a reproductiveconcept. it concerns the ability to produce
successful offspring. that's a species. ifyou can do with another organism then you are members of the same species, a reproductivecriterion for your concept. the bsc, the biological species concept constructed by an ornithologistwhich is relevant because he's thinking about birds. for whom does this definition not workat all if you think about other biologists? what biologist might not appreciate this definition?anyone want a try at that? yes? >> student: (inaudible)>> professor shabel: if you're studying something that reproduces something asexually like bacteriathat undergo binary fission, right. they just split to form their quote unquote offspring.they're not reproducing sexually, so it, it just doesn't apply to those organisms andthat's a major gap if you are trying to be
present an integrated definition. so maybewe can't have a single species definition, and maybe we need multiple definitions tocorrespond to different organisms. that's another problem with reproductive conceptlike this. anything come to mind, probably from the plant section or elsewhere? thinkthey'd inhibit a clean definition like this? yeah? >> female student: some plants self fertilize. >> professor: some plants self fertilize?that's really important, yes. some plants hyberdize. there's horizontal gene transfer.you guys looked at that a little bit, horizontal gene transfer and sharing of genes among organismsthat represent different species by most other
criteria? those types of phenomenon can confusea clean biological species concept, and it may just require some modification. quicklyalong these isolating mechanisms that keep species apart according to the bsc, this is,this is pretty easy to understand. just lots of quick examples i'll give you. for prezygoticmechanisms and postzygotic mechanism leading to reproductive isolation 'cause that's thekey point. organisms need to be reproductive isolated from each other, unable to sharegenes. it can happen before the zygote is formed, prezygotically or after the zygoteis formed, after fertilization, postzygotically. so let's look at examples quickly of eachof these, few local examples. i always try to build in local examples to get you familiarwith the bay area ecosystems and organisms
in hopes that you'll go out and find someyourself, catch 'em. you can catch these snakes out here. we caught couple of these on a fieldtrip last week for another class i'm teaching. aquatic garden snakes, these things live aroundthe ponds around here and eat frogs and they're beautiful little snakes, totally harmless.go catch one. well, they live near the water. we found ours near this little seep, littlewet land, whereas the terrestrial garter snakes are just up land in the drier hill. so youcan have these guys on the dry hill side while these guys are down and these are down inthe water. and tend not to breed together because they're isolated by habitat. so theyjust don't breed together because they don't encounter one another. can they breed togetherif you put them together? that's a different
question. in fact, they're not not breedingtogether as a result of a prezygotic isolating mechanism. skunks like this, there's a beautifullittle skunk that lives around here, this one. it's not your campus skunk with the longstripes that will scare you at night if you walk around campus and turn a corner and allof a sudden you see the aposematic flash of the blackandwhite skunk. it will make youjump. it'll send a chill down your spine because you know intuitively that black and whilethere and signals a danger that you might get sprayed have to live with the stench andthen you, you and roommate for the next week. you know that intuitively because of the aposematicwarning that the skunk delivers. well, there's a little spotted skunk too. the stripes arebroken into spots, and he's a little guy and
he can climb trees a little bit and huntsmice instead of being omnivores little forager in our in our trash cans. and it's a neatlittle skunk. it's called a westeastern western spotted skunk. on my, gosh. your common namesare backward. it doesn't matter, but spilogaleputorius's are local western and spilogale gracilis isthe eastern. they don't breed together. even though they are so similar they breed at differenttimes of the year. one breeds in the fall and one breeds in the spring. their breedingseasons are very short, so when the males and females are ready to breed in the onespecies, they're not ready to breed in the other species. they can't breed together 'causethey're temporally isolated from each other. these examples are fun, and i can talk a lotabout them, but i need to get to through.
behavorial isolation; birds like these, theseare blue footed boobies. they go through an elaborate dance like this such that if you'reanother booby and your dance is just not going to look right to the other bird. and thusyou're not going to reach the point where you form a zygote because you have to go throughthis elaborate courtship ritual to get to that point. so if the dance isn't just rightit's not going to work. so you have a behavior mechanism for isolating this species fromother species. you've got to step just so in order to be successful. these bluefootedboobies are famous from the galapagos, but a couple of them made it all they way up hereto san the san francisco area last year. i don't know if they're here again this year,but they sometimes come this far north especially
in a warming world. might get them in thefair alone islands more consistently. ( meadowlark calling) that's a very familiar sound. youhear that? (meadowlark calling) it's a familiar sound in north america. it's a meadowlarkcalling. and here is another meadowlark. (meadowlark calling) see if you can tell the difference.(calling continues) hear how different that is? you can hear the difference better believethey can hear the difference. they sing differently and they're not going to mate together becausethey don't sound right to one another. so they're behavior is really isolated from eachother just by the way they sing. organisms can be mechanically isolated from one another,physically isolated from one another because of something about their morphology. snailslike these are either right handed or left
handed; dextral or sinistral. they coil oneway or the other way, and if they coil opposite ways they have trouble mating together becauseof the way they the way their reproductive organisms organs are set up. their hermaphroditic,hermaphroditic so they have male and female parts in each snail, but if they don't coilthe same way they can't mate properly. so that's simple as that. there's more of a storythere, but i'll skip it. snakes come into play in an interesting way. you can read aboutit if you google it. the gametes might be incompatible so say that the gametes are actuallyable to contact each other. unlike the snails where they're misaligned, so the gametes nevereven encounter one another. what about sea urchins that deliver their gametes into thewater column and circulate among each other?
well the gametes might not recognize eachother if they even bump into each other physically. the protein coats might not be such that they'recompatible, so they can be separate at the level of gamete itself, gametic isolation.and now we've gotten to a point where, okay, those are prezygotic. what happens if thezygote is able to form what happens from there to help reduce the likelihood of species intobreeding in biological context? ensatina salamanders are an example. some of them do form and hybrids,but the hybrids are tend not to be viable, tend to be smaller and not survived, not foragedproperly, not survived with likelihood, so they have reduced hybrid viability. even thoughthey form the hybrids, the zygotes form and develop into small adults. they're not viable.sometimes the hybrid is very much viable like
the mule. this is a great local barnyard example.i love this case, 'cause mules are these amazingly strong type of horse that forms from the breedingof a horse with a donkey. a horse and an ass makes a mule but the horse and the ass havea chromosomal difference that leads to infertility of the mule, so the mule is fertile, big andstrong and a great work animal on a farm; bigger and stronger than a donkey and moreof just nicer and stronger than a horse, stouter than a horse and more powerful than a horse.mules are highly desirable for work, but they're infertile, and you can't breed a mule witha mule and get another mule. yu have to keep your darn horse and your donkey and breedthem again to get your next mule. that's hilarious to me for some reason. (laughter) hybrid breakdown;just a case where the hybrids form. maybe
the next generation is strong and successful,but over time, over the generations, the hybrids become unsuccessful. just an extension ofthose examples, not critical. all right. once again ensatina. and i'll be finishing up withthis example probably. ensatina, i've just described, our local one. ensatina eschscholtziixantopitica, the one that's a newt mimic here locally. look at its range, eschscholtziiin green. wait a second. no, xanthopitca in purple. it's just that limited range in thebay area and just to south like a described down towards santa cruz county and so forthwith maybe a population out here in the sierras jumping the valley. no ensatinas in the valley.it's too dry. these salamanders need moisture. there's a bunch of different named kinds thatring the valley of california. hypothetically,
came from the north in a previous era. theycame from the north as illustrated in this little video that proceed slowly as the creatureis hypothesized to move down from the north over the millions of years from oregon intocalifornia and diverging along the way into the forms that are blotchy in the sierra side,more uniformly patterned on the coastal side, but differing in coloration each from thenext. so they've changed in their morphology as they've moved from north to south to takeon these different forms. they can breed together so this one can breed with its neighbors successfully.there may be some reduced hybrid viability, but can successfully breed and are, thus,the same species by the biological species concept criterion. but down here in the southernmost part of the range, this form here, eschscholtzii,
and klauberi, when they've encountered eachother having moved down separately on the other side of the valley, they can't breedtogether. they can't breed together at all and are, thus, considered different speciesby the bsc. so this was set up as a challenge to some degree to bss. ernst mayr himselfsaid this is a great example of microevolution changing in populations in their genetic structureand morphology over time and then these small changes that lead to a speciation event downhere. think about it though. if this one can breed with this one which can breed with thisone and this one and this one and this one and this one, so your klauberi here can breedwith all its neighbors, which themselves can breed with one another, it should be the samespecies as this one. but, in fact, we know
it's not so conceptually there's just a violationof the biological species concept. if you work your way around the ring these two shouldbe able to breed with each other but they just can't; so you have a fundamental. it'slike philosophical invalidation of a formal biological species concept. if you reallywant to challenge it that's is an interesting way to do so. so the whole question of speciationand the title of this lecture today, was the one that exercised darwin, right. speciation,these lineage splitting events and creation of new species, how does that happen? howdoes that work? we'll call it cladogenesis when we start to get into phylogenetic systematics.we won't worry so much about about species; we'll worry about clades, we'll worry aboutnew kinds of organisms that form units in
a phylogenetic analysis. that'll become animportant way that we think about these organisms rather than a traditional species context.i have two minutes just to illustrate this point and i'll let you go for the weekend.islands were certainly important to darwin in the galapagos and elsewhere. and what hesaw was that organisms can get to islands and change form. here's a red lizard gettingto this island and going green illustrated like this; a, from the mainland gets to theisland where it finds it to its liking 'cause there's no other organisms there and lotsof resources in step one. and this is his model really from the galapagos as illustratedlater. well "a" may turn, evolve into "b" as a result a result of microevolutionaryforces. founder effects, genetic drifts acting
on its population, adaptation to local environment.all of these things can lead to a new population with different genetics from your mainlandpopulation, its b. and then "b" hops to the next island. so now you have this point intime, a different species living on these two islands. well "b" may have evolved into"c" which then island hops and "c" evolves into "d" and so forth, so you get this overlayingof patterning that can lead to the complexity
of something like the galapagos through speciationas a result of the courses that we've outlined. any quick questions before i let you go havea great weekend? let's talk about it afterwards. we've got so much to talk about. any otherquick ones? do you have time to come on up and we can chat? i hope so.
