 Hi everyone, if you could take it off the slides for a minute. I'll just talk about some course logistics We are still troubleshooting our process here bear with us while we do so Course logistics one for one thing I'm going to be arriving in At the last minute for the lectures this month my kids just started school and one of the schools doesn't even open until 745 so I'm there my wife's at work earlier and then I'm then I am and then I'm hustling over here So I will try to be here on time and to start at 810 But please realize I'm running across campus to do so so I might be a couple minutes late Office hours are as listed on the website every day after lecture for one hour in 3095 VLSP on Monday and Friday and 3059 VLSP on Wednesday, so that's the place to go over questions from the lectures Course material from the books And we can also set up office hours by appointment for anyone who has class time during those those slots I put on the on B space just a folder where I'm going to occasionally add News links for interesting things in ecology in the news It's on B space in the resources folder. I put something in there yesterday regarding a mountain lion that was Seen and then shot at Shattuck and Cedar in North Berkeley here Yeah, the don't panic don't panic. It's dead They did shoot it. They were the police shot it They had to make that decision. They gave it some time. It jumped a few fences hidden people's yards It was a 100 pound female lion That's very unusual they are in the hills that they are in in the local areas They will more and more be encroaching in suburban areas and cities It is to be predicted over the next years, but to get one I mean I look I look for them. I look for their sign And it's very rare to see them even just in Tilden on the edges To get one all the way in town is pretty remarkable yeah, so They won't always be as exciting as that these types of reports But things from the times or things from around the world regarding biology you can just look at there not to be examined on just for fun any thing about course logistics that you have questions on or Anything about the presentations that's that isn't working for you that you need to troubleshoot or that you would like to give advice on just send me email and I've been able to respond thus far. I haven't been inundated yet So I should be able to respond to you if you if anything comes up Okay today we are talking about We're getting into population ecology Demography and life history Really today and tomorrow we'll be talking about population Ecology I've given myself a giant cursor here so that people in adjoining rooms In the adjoining rooms can see it because they can't see my laser pointer So I'll try to put my laser pointer down and use this as much as possible So we'll be starting with just a general look at population structure and the factors Influencing population numbers numbers of individuals and populations We will look at mechanisms methods to estimate population size the phenomenon of dispersion within populations Briefly talk about Metapopulation dynamics the metapopulation concept and Then we will focus on life tables life history tables and survivorship curves and a bit on Life history trade-offs and that'll be our segue into discussions tomorrow Here's here are a bunch of sparrows to represent a population there in the middle of the figure We are taking a snapshot approach to populations nature is highly dynamic, of course nature is Incontinuous flux right But very often we need to stand nature still to observe it and to quantify what we see and We do this very often when estimating population numbers. We assume a a lack of change in In the population with regard to the major forces that influence population numbers What forces do influence population numbers here? We have our our little collection of sparrows this interbreeding group of individual sparrows individual sparrows that have the potential to Interbreed with one another and thus share genetic material another name for a little group like that is a deem D-e-m-e and that gives us the basis for our word demography so this little deem is comprised of individuals and The numbers are influenced by four major forces. They the numbers may increase as a result of births or the arrival of new individuals through immigration and The numbers may be reduced by deaths or the departure of individuals through emigration Right, so birth and immigration add individuals to the population death and emigration Subtract individuals from the population. Those are dynamic processes. Those happen over time But for simplicity we're often forced to Freeze the population in if we want to make estimates of numbers in the population So let's look at how that is done in the field Absolute density so measurements of absolute numbers of individuals attempting to estimate Actually, exactly, you know, well not not exactly. It's always done with error But to estimate absolute numbers of individuals in a population Imagine your eucalyptus grove right outside the building here if you wanted to count the number of trees It wouldn't be too hard because they stand still for you You could you could mark them as you go to make sure you don't count them twice But if you're careful and patient enough and there are few enough distractions You could count every individual and be very accurate about it. They're sedentary Organisms these eucalyptus trees. It helps a lot when counting for Motile mobile animals and organisms It's somewhat more of a challenge, but you might imagine for some large animals like Ungulates on the top there. Those are ibex I believe in North Africa you could fly your plane overhead if the if the deem is small enough and count them one two three four five six seven eight nine ten eleven twelve you get the idea and Be fairly accurate, especially if you're on an open grassland and the group is that small a bunch of elephants If you're on the ground You might be surprised how hard it is to track and count them, but again You might be able to be fairly accurate a friend of mine a colleague of mine from Southern, California Has been studying peccaries which are like a like a forest pig in Central America in the rainforest in Central America They've been using paintball guns to Pop the pigs they're big animals and they can take it But then you get a nice splatter of blue paint or whatever it is and you know that you've counted it And it'll stay for a couple of days and they're having a great time So Those are methods to get a counts of absolute numbers of individuals in populations Very often you can't count everyone because there are too many or because the area is too large and You use a sampling method very commonly used methods include Quadrat the use of quadrats to lay in a grid of Known area over a surface and to count the individuals Observed in that grid and then to extrapolate to a larger area From what's estimated within that local area or to run a transect for example on the coral reef here to run a transect and To monitor the number of individuals touched along that transect and to extrapolate mathematically from there to an area these methods depend on certain assumptions and We'll look into a few of them as we go These techniques are great again for they tend to be best for sedentary for animals that stay stationary animals like this fish or large vertebrates tend not to so one of the Tried and true methods for dealing with organisms particularly larger organisms that move around is to Is to catch them or to somehow mark them and then to resurvey the population later And I'll just give you the very basic math behind the technique so on The top we have a population of individuals uncertain unsurveyed, okay and We we perform a Survey we we take a sample of the individuals in that population from that region of the space occupied by the population and We capture that many individuals. It's looks like it's 12 individuals and we mark them somehow You might if it's a snail you might put a little nail polish on its shell if it's a rodent you might Clip a little bit of its ear that won't grow back And so you know it has a when you catch it again that it has a little notch in its ear that you made Or if it's a bird you might put a band around its leg or something like that You sample it somehow and then you release those individuals back to the population Those individuals become reincorporated in the population and Mix with the original population then you sample the population again Ideally at a relatively short interval after a relatively short interval of time as close to The time after everyone has mixed back together again as possible and you take your second sample and say in this case you catch 15 Organisms and you find that four of them have tags So let's see what we can do with that information Because what we want to estimate is the total size of the population of the original population that we didn't have the luxury of Sampling in Toto because either the space areas too large or the individuals were invisible Usually it's resource limited you just can't You just can't do it either for the finances or because it takes too long or the space is too great But there's a nice way to estimate the number from what we've just done in our surveys We're interested in total population size estimating that that's capital N for number of individuals The simple equation we can use is based on the fact that in our recapture the proportion of individuals recaptured with marks to the number recaptured Should be equal to the ratio of the original number of marked individuals to capital N to that total population size and If you spend a couple minutes with that you'll you'll see why that that's the case why M over N equals X over N in this equation and if since we're interested in total population size capital N we can just solve that equation for N and and use those variables M the marked individuals from the first sample the number of marked individuals from the first sample times the total caught in the second sample divided by The number of marked individuals recaptured in that second sample So there's our there's our simple equation to do so Returning to our example we marked 12 individuals so M equals 12 We released them back into the population and then resurveyed recall and in that process we Captured 15 individuals in total only four of them were marked and So then if you just simply plug Those numbers into your equation You can solve for you can you can generate an estimate of the total population size 45 it's always done with some error, right and I think if you count them up there are 41 individuals there So we got pretty close close enough for government work as they say and the the work goes on But what are if this is going to work? What are some of the assumptions? That you must make you don't have any ideas on that if you're going to get an accurate estimate here What's an assumption you might have to make? Yeah, and how might population size change between sampling you could have deaths Yes, that might change so you assume that there's no mortality Between your sampling intervals What else? Yes, you have to assume that the individuals reintegrate into the original population and they don't just Hang out in one corner of The sampling area that you might miss entirely if you visit the other corner you need to assume Reintegration what else anyone can anyone think of anything else? Yes No immigration or emigration, which is similar to What someone else said about death because those are the among the other factors that might influence numbers that aren't related to What you're trying to estimate here Yes Yes, perfect. You have an equal chance of catching the ones that were marked versus the ones that were not marked and in other words You don't have Animals that are capture shy or capture happy We Memologists actually speak of trap happiness because some organisms just seem to get back into the trap again and again and again And then you know in a case for example with rodents Where you set up a trap and it's got oats and peanut butter and a little cotton inside It's a rather luxurious hotel for the night for some of them I guess Because they have spent one night in there eat well or released and back they go There may be even a genetic basis for something like that Whatever it is some organisms do avoid that avoid such capture and some of them seem to be attracted to it And that biases your sampling those are great Suggestions there may be other assumptions that go into this thinking about density Just be aware that you're going to need to use different techniques for different organisms in Part because organisms come in different sizes and the sizes of the organism The size of the organism is related to their density You're not going to sample bacteria in the same way that you're going to sample birds and mammals This is just a birds and mammals example sticking with our theme of using them quite a lot and Something to recognize here is that as body weight increases The density of the populations decreases for both birds and mammals But that the slope of this line the slope of this regression is lower for the birds than it is for mammals so at a particular body weight say 10 kilos the Average number of individuals of birds in the unit area is going to be lower than the average number of mammals in that area Okay, so those are just a couple of things to bear in mind about creatures will build on that insight as we go and the relationship of body size to To life history and biology body size is critically important to most life history parameters Including well, it's also related to density those were We were just looking at absolute ways to estimate density to generate You know an actual number even if it's a even if it's an estimate like we got from our mark recapture survey It's still we're producing an absolute number in the end, but you might just Be okay with a relative estimate of of density and To do that you might study the sign of Of an organism you might compare to Two sandy areas and count the trackways Along those sandy areas and if one area has a dozen sets of track ways, maybe you can even distinguish individuals so you know you have 12 distinct individuals on This surface and in another site in the same interval of time Holding all other factors as constant as possible you find many fewer you might be able to say this sandy area is More dense in what in this organism than the other Right and that might be sufficient if you're interested if it's a conservation motivation and you just need to figure out quickly Where more individuals are if you're going to put up a house on this beach versus that beach something like that you might Get away with a technique like this or you could count What are sometimes called artifacts? These are chimneys produced by crayfish burrowing underground you could survey a surface and count chimneys and that if you if they're one-to-one or Proportional to the number of individuals present the counting chimneys is almost as good as counting Animals or you can do scat surveys so all these are all these are forms of sign or or as you sometimes hear in the old world spore sp-o-o-r it's just a another term for the sign of an organism whether it's a trackway or a Fecal droppings or artifacts like that Let's help you with relative estimates of density If we're interested in tracking the movement of organisms in relation to immigration or emigration say Classic methods include putting radio collars on and I just Searched on radio collars and found a bunch of fun images You know these things are often big and bulky They have a big battery inside and then you walk around with a unit and The signal is sent to your unit indicating to you the direction the position of The organism with the collar there They can be a bit clumsy because the bigger the battery the longer lived the radio collar But the heavier for the carrier and that's a point we could have made in our in our assumptions about Mark recapture methods these these can threaten the life of the organism Not only the the collar but the capture process if you anesthetize this big bear That's a risk to the to its health of course you're taking that risk in order to learn something about the population and hopefully bring a better understanding and for conservation But a risk it is and in the mark recapture method you have you need to assume that mortality is not increased for the individuals You tag but if you catch a fish and keep it out of water and then tag it It may very well increase the likelihood of its mortality So radio collars are the bigger the better because the longer they last but they can often be very clumsy on the creature There's a there's a wolf fitted with a collar just to give you some ideas of what people are doing in the field Everyone loves the dwarf bunny An endangered species of dwarf bunny That's my favorite I like art barks Art bark with a radio collar and these are burrowing animals these are animals living underground and that's a huge leather collar so that's really cumbersome and Probably slows it down in relation to the hyenas and all the rest But if you want to know how far the art barks are moving at night You really don't have much other choice because you can't as big as it is you can't follow an art bark for very long On foot without a collar Everyone knows meerkats now right they've been they've become quite famous Or Tasmanian devil and you can get very small with them, you know a harvest mouse or something like that Little collar on those one of the things I study in Africa are our land snails giant land snails and during the summer They during the dry and warm season they they go underground They disappear and I would love to put a radio collar on these snails and follow them. It would just be fascinating But you really need to be on the ground and you need to invest and put the resources in Yeah, you get the idea Something else that's frequently used to monitor movement are pit tags Passive integrated transponder units these these do not have a battery in them So they can last much longer and they're very tiny So they can be even injected with a syringe under the skin of an organism And you might you know they can be used for pets because they they're Provided with a certain amount of information in whatever kind of chip it is they contain and then when stimulated by a reader by a scanner They'll they'll provide that information back so if you catch a if you catch a turtle on a beach you could enter the information the day on which it's caught the time and the location and put the pit tag in and years later scan a turtle that washes the shore and If it has a pit tag in it retrieve that information and get to know something about its pattern of movement Dispersal you can do it with fish. You can put it under the skin of a frog Very handy. Let's think about the way individuals are dispersed within a population And that's one slide if someone from one of the adjoining rooms could tell me later if they're seeing the edge on it Then I'll know better What's fitting over there? Yeah, so individuals in a population How are they how are they separated around? Units of space We all distinguish three types of dispersion uniform dispersion those rep dots representing the individuals with relative You know with approximately equal amount of space between individuals or a more random configuration or a clumped or patchy I'll probably use the word patchy more often. I think your book uses clumped a patchy configuration Which of these do you think is most common for organisms? I heard a lot of clumped out there. Yeah It by far But let's look at some of the The forces that generate these different patterns And I I would want you to go back and think about our sampling techniques and how the sampling techniques might depend on some of these dispersion patterns so patchy Distribution clumped distribution on the intertidal that space between high and low tides on a coastal shelf Where in this case you have a bunch of starfishes and and mussels and barnacles and some algae Distributed clump clumpily Why might they be distributed in clumps here in this case? Yes Food resources, maybe there that's where they can find things to eat in the case of the starfish. These are mobile And so they can move around and seek their food resources, but these other creatures are much less mobile So it still might apply, but it might apply most particularly in this case to To the starfish What else? Yes Protection from predators. Maybe it's a more sheltered spot and to avoid predators. How about something else? Yes The water what about the water? Some places that have water at low tide so the first two Food and predators those would be biotic factors, right influencing dispersion patterns here patterns here the example of how water might influence it we could add exposure to air and sunlight at low tide as Abiotic factors that might influence the distribution non-living factors factors of the physical environment and that's often a major structural aspect of these intertidal communities exposure to desiccation to drying out and organisms distribute themselves in many cases spatially as a result of physical factors uniform distribution in these penguins We'll give you another example of that in a second Random distribution in these Dandy lions. I think they are Where the entire area is suitable habitat and Where the seeds land where they're blown to and happen to land and germinate and establish is Basically random all sites being more or less equal in suitability for growth Giving you this kind of random pattern and that's what's just so often not the case The environment is not Homogenous like this allowing suitability of growth across space in a uniform manner Use the word uniform there. I really shouldn't have because I want to use the word uniform more specifically So these are these are like the penguins. These are gannets. These are breeding a breeding population of gannets and If you look at their nests Look how they're distributed. What kind of dispersion is this? Uniform they're more or less equally separated The distance of separation is related to what? Territories really how long their neck and bill can reach before they peck at the other one, right? You need to be just far enough away that you won't be harassed by your neighbor and that gives the individual bird enough space to Feel comfortable in raising its chicks. So that kind of Inter-individual interaction Produces the spacing That leads to the uniform pattern Little audio if you go into the Berkeley Hills if you're not scared of the mountain lions And let me just say right now Mountain lion attacks you're more likely to hit be hit by falling airplane debris, right? If you walk in the hills then you are to even encounter a mountain lion probably They are really not not a risk around here. So please do go into the hills up to Up to Lake Anza and Jewel Lake and the Wildcat watershed It's just over the hill here and if you go up there you might hear You might hear that if you're fortunate and you spend enough time there it would be the call of a of a kingfisher and That's very often a territorial call It's alerting the other birds in the area that it is present and other birds would know to stay away from its turf and Through mechanisms like that or otherwise Territorially marking your habitat often with scent markings urine or feces Many animals will spray that up and spray it into a higher spot and then the other animals will come around sniffing around and know who is where and Territories will be established in this way Maybe the ter the perimeters of the territories will be marked in this way and it may produce a Uniform distribution of individuals. How about these these semi-arid plants here? They are relatively evenly spaced about this surface Why? They're not urinating on each other, right? They're not Calling out to each other and separate or pecking each other. So why might they be uniformly distributed? You guys have been great with your answers. Yeah Resources, what do you mean? The amount of the amount of nutrients or water that they can take from the earth in that area Can someone build on that? Yes, excuse the root systems. What about the root systems? Yeah, perhaps the roots need a certain amount of space and they become intertangled. Yeah, I think You could build on that a little further and think that maybe these root systems and these plants require a certain amount of resources that they take up from That space and if it's say water and nutrients that are limited It just might not allow for growth of other individuals in close proximity So once they become established and start dominating that resource Acquisition in that spot others can't grow there. Maybe that's what you two are hinting at And that is one possibility What's another possibility? It's kind of technical if you might need to know something about plants To know what might be happening here, and it often does plants are very good at this. Yeah They can release chemicals that prevent germination or that kill other neighbors I think I added the term here. Yeah, allelopathy or allelochemicals Is just the name for that you'll learn more about that in botany But that can also give rise to uniform distribution fungi on a tree trunk What kind of dispersion pattern? Yeah, you're good to hesitate For one thing it can be just hard to assess the fine details of what's happening here But I include this and I include the next slide because I want you to think about scale on That trunk itself that might be uniform or random. I don't know you'd have to you'd have to quantify it But think about the forest as a whole they're only going to be a limited number of dead logs and At the level of the forest as a whole it's almost certainly going to be patchy the growth of these fungi Think about a landscape like this and think about lichen Maybe you know what lichen is right? It's actually a symbiosis of fungi and algae. You'll learn about that later But lichen grows on surfaces like rock surfaces or the trunks of trees think about the distribution of lichen on this landscape and It's dispersion patterns and try to move across spatial scales In ecology we move across levels of organization quite nimbly And you need to be able to move across spatial scales Nimbly as well Ecologists are doing that all the time. They're very flexible in that and so try to Try to think about things at different spatial scales as much as possible. I want to introduce the concept of a meta population there's a definition for you and I'll present this concept of a meta population As as an approach really as an approach to the study of populations. It's not a distinct level of organization or something like that It's an approach to the study of populations The cons the the concept can be defined as a group of spatially separated populations that interact through immigration and emigration Most organisms are distributed patchily like this in patches of suitable habitat But note that some areas of suitable habitat remain unoccupied They are perfectly livable But they're just not occupied because the individuals there have gone extinct look in that local spot or for historical reasons Individuals just haven't arrived for whatever reason But over time that changes Individuals arrive into these patches from previously existing individuals and other patches and individuals in some patches will go locally extinct and become unoccupied so Ecologists study this dynamic process And there are it's a particular sub-discipline within ecology journals dedicated to it And it's very much amenable to mathematical modeling and it's a rich field of study A great example given in your book from these butterflies in Finland where the investigators Surveyed and you can see the the distance here is five kilometers So over a very wide area surveyed the number of available patches of habitat represented by the Empty circles and the number of occupied patches represented by the filled circles and followed this over time as these patches blinked in and out with occupation and local extinction and Modeled that dynamic. That's a study of metapopulation dynamics, let's move into demography in our last Ten minutes here Demography was largely developed in the study of humans human demography It's but it's extremely important for ecologists as well and major contributions have been made by ecologists It's been a nice cross-fertilization of human biology and non-human biology over the years And there's just a reminder of our term deem Which is sometimes useful To distinguish it from a larger population Those are Don't intend to have audio for this. Yeah, those are buildings ground squirrels up in the Sierras I was up there last week with my family up in Tuolumne meadows, and we got to see and hear these little guys great study given in your book on This species of ground squirrel Don't be too distracted by the film. Let's look at the columns here. They are awfully cute a Life table is a table structured according to cohorts individuals of the same age Most thoroughly studied when you follow a certain number of individuals At the start of a time period of a certain age and follow those individuals across years According to their survival So these are this is this is really a study of I should just stop it Should either just show it separately or stop it Yeah, here comes the kitty cat the squirrel the squirrel survives Just as you will in the hills when you make your next trip. All right The proportion alive at the start of the year if you know how many are Alive at the start of each year you can calculate the proportion of them that have made it to the following year Of course the cats and the hawks and things are going to be and the very very cold winters at 10,000 feet are going to be killing these things A certain number of deaths will occur each year and you can calculate the death rate from this data From any one column you can you can generate the other columns information note that the Life history data for females is different than it is for males. That's often the case for mammals and birds and humans Such that when you plot a survivorship curve Note that we're on a logarithmic scale here And if you're not remembering the difference between an arithmetic scale and a logarithmic scale you can discuss it in section Note that the curve is different for the males than for the females the females tend to survive longer a greater number of years and mortality Rates are higher for the males Given the steepness of that of that curve Okay, I'm gonna fit the rest of this in so we'll just carry forward The book the book does quite well on this subject and you'll learn a lot more in your labs and discussions But let's think about other creatures right. Let's not Think about just mammals or humans think about a giant clam releasing millions of eggs Unlike the squirrel which would just be producing a small litter millions of eggs produced They can't all survive. That's a really big clam and even though the Great Barrier Reef is really really big Also, you can't fit that many clams With each one producing all those eggs and having them all survive massive mortality is going to occur in this process and You know, this is one of the one of the ways in which it's going to be it would be great to be building on the evolution section because so many Darwinian insights come from Insights into this phenomenon this this the fecundity of creatures So organisms differ very very much in this regard in in their production of offspring For creatures that produce massive numbers of individuals for which mortality Occurs dramatically in the very earliest stages the survivorship curve might follow this type 3 Configuration represented here by an oyster very much like what would happen with the clams huge numbers of eggs broadcast out into the open water hoping that some small number will actually Establish and survive those few that do establish and get Firmly situated tend to live a long time Because they have a good space and they become too large to be dislodged if you're a big oyster and a little egg lands and Becomes a small individual oyster. It's not going to be able to knock you off You're you're just you're too big for that So once you're established you tend to survive a long time, but mortality is massive in the earliest stage the squirrels They tend to have a likelihood of survival across time That doesn't the rate of of death doesn't change much over time If the start of the season there are 50 squirrels, maybe half of them will survive to the next year and Then the following year well half of those are going to survive no matter whether you're two years old or four years old Your chance of survival across the year is maybe 50 percent because once you get to a certain age You're You're equally likely to get nailed or to die of freezing as you are at twice that age humans and many large mammals follow a different pattern where Although there is higher mortality in the very earliest stage of life During birth immediately after birth perinatal Once Established the end of the likelihood of survival is quite good until a certain period of senescence after which the likelihood of survival becomes quite less good and One of the reasons why human Demographers were so important in the development of these fields is this is important for life insurance companies, right? They need to know this schedule of death in order to in order to schedule The costs and returns of insurance So three types of survivorship curve, and we will call them types one two and three that's traditionally the case and Some examples of these different curves showing the difference in females and males In homo sapiens ourselves Types one two and three the fact that many songbirds also follow a more or less type two configuration or a more type one configuration in a flowering plant and Reproductive tables where those are real the the life tables are focused on Our focus on survival and death Reproductive tables are more focused on the birth process and natality. We'll get into those more tomorrow when we look at population growth just a Little introduction there hang with me for five more minutes, please a few of you need to leave right now I guess but I'm going to fill up the time here. So please hang with me trade-offs in life history We always need to be thinking about about trade-offs Again, we're not building on the evolution section But in general it behooves an organism to leave as many Viable offspring as possible in a Darwinian context in the context of natural selection We increase our fitness by leaving as many viable offspring as possible and in and Magnify our genetic contribution to subsequent populations by doing so But you can't if you're a kestrel just Produce a massive clutch of eggs and the more eggs the better you can't Perform that way For one thing it's expensive to produce eggs it takes energy to make them and for another Who's going to feed the young well you have to and so You can't feed 30 young in your nest with the resources that are available in the local environment Given the constraints of rainstorms that are coming through and the competition from other individuals There are many constraints acting on these creatures energetic competitive biotic and abiotic that limit the capacity their capacity to to reproduce and so in this nice study taken from the book it is an experimental manipulate manipulation study where investigators went in and actually reduced the number of eggs in the nests of males and females or enlarged the number of eggs in those nests or Left them untouched and then followed the survivorship of those parents the following winter during the the season of dearth the difficult season where if unless they have enough energy themselves they won't make it through that season and When the number of offspring were reduced males and females had higher survival than normal in that subsequent year showing the energetic cost of raising a brood of eggs and a brood of young and for Eggs that were added to the nest for broods that were artificially enlarged the parents and maybe the males in particular Had difficulty surviving that following winter having raised that many young Or attempted to do so they depleted their own energy and weren't able to survive the following winter So we got to always think about the trade-offs in in these processes Finally, I'll just introduce you to a couple of new terms in terms of demographic traits Because some organisms reproduce repeatedly throughout their lives humans do These scorpions do they repeat they they reproduce produce this this brood of organisms send them off on their way and In this case perform some parental care send them off and then do it again the following year But others will only reproduce once in their lives and you can call this semoparity or big bang reproduction They've they put all of their resources and it may take decades into one massive reproductive bout and I want you to think about Why the conditions that might give rise to these different strategies? Famously the salmon that run in the rivers in the Northwest they spend their Their youngest portion of their lives swimming down river Get big in the oceans and then migrate back up river to spawn at the sites in which they were born The males and females congregate at those spawning sites as original spawning sites Having made it there past the sea lions and the fishermen and the grizzly bears. They finally make it Put everything into the they're completely exhausted put everything they have left into their reproductive effort, and then they die That's semoparity, okay, and you can think about rhinos and coconuts as opposed to dandelions by looking at the slides Thanks everybody