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Christoph Richter

Lecture 11- Chapter 12: What is metapopulations: -set of subpopulations that are connected by dispersal or movements in and out of the region - there is always a core population where dispersal is the highest and emigration and it has the lowest risk of extinction - metapopulation as a whole never changes but minor changes in sub pop. -metapopulations has 4 conditions: 1. Suitable habitat that OCCURS in discrete patches:- it has to be large enough to support breeding populations 2. Subpopulation cannot be too isolated 3. Every subpopulation is substantially at risk of extinction ( including the largest subpop) 4.dynamics of subpopulation is not synchronized -2 set of processes  that have distinct scales: 1. Local – within patch= within a subpopulation interaction btw ind feeding and breeding controlled by births and deaths 2. Regional or metapopulaton=dynamics are based on the interaction btw the local populations and is controlled by dispersal and colonization and depends mostly on the ability to recolonize since all subpopulations have some risk of extinction -colonization= the movement of individuals from occupied patched ( existing local populations) to unoccupied patches ( new local populations) -when these individuals are moving across other habitat patches…they don’t colonize in them because they don’t fit their feeding or breeding type - the prob with colonization is that these ind are at some risk of failing to find a habitat patch that fits their requirements - dispersal is a key feature in metapopulation: - if there is no dispersal the subpopulations will function independently - if there is high dispersal the subpopulation dynamics will be depend on one another and may even have dynamics that synchronized function as one continuous population. - if the dispersal is intermediate then the local extinction and recolonization will be at balance… The dynamics of the metapopulation influenced by variables: -Extinction (E)= when the dots are disappearing. -recolonization can occurind moving in and out of the patches -each subpop varies in their prob of extinctionif extinction occurs the proportion of habitat patches increase -Colonization (C)=the movement of individuals into and out of patches to unoccupied patches - proportion of patches occupied (p)= if the subpopulations full = no one can come into or switch There are 7 factors that influence these variables: 1.patch size= how large is the patch size..how much individuals live and can occupy the habitat patch and how much can it support its individuals 2. The distance btw the patch size= if its too large then interaction and movement btw the patches will not occur. 3.habitat heterogeneity= 4. 3 variables that influence the dynamic of metapopulation - Extinction (E)= when the red dots disappear - recolonization occurs movement of ind in and out of the patches - when subpopulation goes extinct there is an increase in proportion of habitat patches colonized (p) - Colonization (C )= the movement of individuals into uncolonized patches ( new local pop) and out of colonized patches ( existing local pop) - Proportional habitat patches colonized (p)= if subpopulations are all full then no more individuals can come into the patches or switch…however if they go extinct then they can These variables are influenced by several factors such as: -Patch area= the larger the size the more subpopulation -distance btw patches= if the distance is too large there will be no movement or decrease in movement - habitat heterogeneity with patches= we assume that all habitat patches provide the same amount of nutrients and protection etc…when in reality these things do vary a lot ( some more better than others) - sources= when resources are full ind move out + sink= when resources are empty and ind move in = when patches area large= more subpopulations= more sink and sources -species diff= some species are more at risk of extinction than others -synchronization of subpopulation dynamics=weather - Lake ontario= we do have metapopulation of fishes but the water they live in is too cold for them it has to be atleast 14 deg C they cant breed if the water is so cold so we created a habitat env condition for them that’s warm enough to live and breed Lynx= the most endangered cat species in the world. Appling the 4 conditions of metapopulation for the lynx: -suitable habitat that occurs in discrete patches ( IT OCCURS IN PATCHES) - every subpopulation even the largest one is susceptible to some risk for extinction ( E=HIGH) -subpopulations can’t be too isolated -dynamics of subpopulations is not synchronized Extinction and colonization: The goal or idea for metapopulation to continue to exist is to maintain a balance between the rate of extinction and recolonization. -for Local extinction to occur the habitat patches of other populations must be reasonably isolatedbecause for metapoplation to continue dispersal and movement of ind must occur and the sub populations much be close with one another in terms of distance….but because of the large distance these subpop. are isolated…so if one habitat patch has the proportion of habitat patch colonized (so its all full and no more ind can come in ) which eventually leads all the resources to run out…and the pop keeps increasing because of birth…then eventually this pop will soon start to drastically decrease…and when they do they wont have anywhere else to go…so the Rate of extinction increases even more…most pop that do go extinct is because they are isolated from other habitat patches - so if the immigration is higher than the rate of extinction it means that they are not isolated and so if the population is growing its because of immigration RECALL if there is high dispersal the subpopulation dynamics will be depend on one another and may even have dynamics that synchronized . THE CONDITION FOR METAPOP= that dynamics is not synchronized.  this means that the local populations will function as one continuous pop ** IF YOU DON’T HAVE DISTINCT SUB POPULATIONS THEN U CANT HAVE COLONIZATION… IF THERE IS HIGH IMMIGRATION THEY WOULDN’T BE DISTINCT BECAUSE THERE IS So much movement btw the two that their pop dynamics become one.--> RECALL they have to be distinct and dynamics cannot be synchronized - if colonization is lower than the rate of extinction then it wont offset it ( get rid of it) because for population to stop going extinct, colonization must occur…so these individuals who are at much higher risk of going extinct have to be able to move from the occupied patch to unoccupied patch ( that provides them resources ) and if the colonization is lower it means that these subpopulations are isolated so no dispersal is occurring which is what makes a metapopulation…therefore metapopulation will not continue to exist. - LOOK AT THE NOTEBOOK FOR EQUATIONS AND UNDERSTANDING THEM* Patch size and Isolation: --if colonization is low ( decreases)Isolation increases -if the patch size is small (decreases) extinction increase -* however patch size can make up for extinction if it has decreased isolation increase recolonization therefore reducing extinction -if the patch size is large (increase) decreases extinction -* however, it can compensate ( make up for it ) for reduced rate of extinction if colonization decreases and isolation increases- therefore increases extinction Habitat heterogeneity: -we assume that all habitat patches offer the same amount of food, protection etc… - when you have a patch size that’s large it influences the persistence of local populations and increases the environment heterogeneity ( so more biodiversity) - so if a natural disaster was to occur the patch size that small will be more affected because the main resources would be wiped out or endangered for the dominant species…however in a larger patch size the conditions will be still favorable…one part of the resources might be affect but other parts are more likely to have it. Rescue Effect: -rate of immigration ** plays a key role= aka the rescue effect because it allows local populations to persist prevents extinction from occurring -as long as there is network from mainland pop with other popsspecies will not go extinct -habitat quality varies ** every patch varies in its habitat quality this allows sources and sink population to occur…source pop= offer better quality and have a positive growth rate (R>0) than sink pop (-ve growth rate R<0) but because the source population is usually full or more than full individuals eventually migrate to sink populations. -Synchronized dynamics: - plays a key role in persistence of metapopulations - if extinction is independent in the local populations then metapopulation extinction will be reduced with growing number of local populations -however it is still susceptible risk of extinction due to demographic and env factors (such as weather and land changes) that can synchronize dynamics. Species characteristics: -species vary in how susceptible at risk they are to extinction and ability to colonize - mode of reproduction, fecundity rate, dispersal mechanism and longevity all play a role in how the species will colonize or disperse - body size and mode of thermal regulation can tell you the probability of extinction under env stoichasticity ( quality of lacking any predictable order or plan) 4 hierarchical concept of population: -Demography ( local population) -Movement ( metapopulation) -Evolution ( subspecies) -geography ( species geographic distribution) LEC 12 CHAP 13= SPECIES INTERACTIONS -Equation = dN/dt=rN(1-N/K)K= pop size that an area can sustain with constant factors -We have to include other species/pop in the equation because they also affect the carrying capacity - individuals from each population interact with ind of other populations - affect population in 2 timescale: 1) demographic(local pop) of birth and death & 2)survival and reproductionnatural selection species interaction=evolution -classification of species interaction and their effects on one another (+) (-) or (0) 1) Neutral= (0)(0)= the two populations don’t have any effect on another. 2) Mutualism= (+)(+)= both population of species benefit from one another The tiny blackbird plover acts as a toothpick for the fierce crocodile and helps by removing tiny morsels of food that is stuck between the crocodile's teeth. These food  particles are the source of food for the bird.  Another example is between the ostrich and the zebra. The ostrich always moves with the herd of zebras since it has a poor sense of hearing and smell, whereas the  zebra has very sharp senses. The ostrich has a keen sense of sight, which the zebra lacks.  3) Commensalism (0)(+)= one population benefits while the other is unaffected -eg. tree trunk provides the substrate on which orchids grow on + condition that benefits the orchids with food, nutrients etc. and so it resides on the tree trunk 4) Amenalism= (0) (-)= one species is unaffected while the other is negatively affected - tall plant shading over small plants 5)Competition= (-)(-)= both hve negative relationship and badly affect each other - small beak finches and large beak finches eating intermediate size seeds that are only available 6) predation= ( +) (-) one benefit while the other is killed eg. lion eating a dear 7) parasitism (+) (-)= the parasite lives in the host and eats and lives off the host but does not kill host just reduces its fitness - There are two forms of parasites ­ endoparasites, living in the host's body and ectoparasites, existing on the surface. -eg. HEADLICE OR BED BUGS 8) Parasitoidism=(+)(-) one benefits (parasite) and kills the host -eg. wasps & flies lays eggs inside the host as the larvae grows grows it slowly kills the host Population Dynamics: -Species interact with each other it involves the interaction of individuals organisms within their respective populations. They influence each other’s survival and reproduction rate as well as collective properties of birth and death influence the dynamics of populations. Natural Selection: So there are birds with different beak sizes ( birds with small beak size and birds with larger beak size) since small seeds are much easier to break larger beak sized birds and small beak sized birds feed on the smaller size to the point this act as natural selection force and causes the plants that produce the small seed size to decrease in its survival, reproduction and fitness and increase the survival, reproduction and fitness of the larger beak size and the allele frequency of the larger seed size increases there force it leads to an evolutionary change - this inturn causes the birds with small beak to decrease in their survival, reproduction and fitness causes natural selection to favor the birds with bigger beak size and leads to an evolutionary change since the allele frequency of larger beak sized birds increases. – SELECTIVE PRESSURE cause a shift in the phenotypic distribution -Phenotypical variations exist within individuals that can result from the differences in the degree and nature of interaction that occurs. - it influences relative fitnessprocess of natural selection -coevolution= 2 reciprocal evolutionary changes occur THROUGH NATURAL SELECTION - mutual evolutionary change intensify -detrimental evolutionary change reduced The ratio of ear to forearm gave u an idea of what these bats are hunting and the wing size tells u how fast etc so compared them from Ontario to West Africa and found those in Ontario only feed on insects while those in West Africa feed on more range/variety of prey, prey type etc… insects, fruits, other bats etc. Geographic distribution: - species that are widely geographically distributed often have a broad range of biotic interaction -if chances occur to these interaction that it will affect their phenotype…selective pressures and adaptations -different local pop differin the type of interaction result in genetic differentiation and local ecotypes -eg. if you have metapopulations of Gazelle…one subpopulation interacts with cheeta while the other interacts with lions so because they have different encounters they both will adapt differently (eg. the ones with cheeta will be more faster than the ones with lions) Diffuse interactions: - most interaction only involves 2 species and its not exclusive however, some involves a number of species - eg. in terrestrial env insects, birds + herbivores etc they all feed on one thing etc Ecological Niche: =-abiotic components that a species needs in order to persist (survive and reproduce) and it uses an array of essential resources - species most v role within an ecological community. Niche=range of conditions an organism can exploit -fundamental niche= aka physiological niche ecological niche of the species that does not include interaction of other species full range of conditions in absence competition -realized niche= ecological niche of species that includes the interaction with other species. -species interaction can either expand or restrict fundamental niche depending whether if its beneficial or detrimental.  exploited range of conditions as a result of interaction with other org (i.e. species) - so there are these two types of cattail T.l grows in shallower water and T.a grows in deeper water further from shore…they both can grow in shallower water…but when T.l was introduced it outcompeted for resources such as nutrients, sunlight and space limiting T.a to grow in deeper water from 20cm or deeper whereas without it it grew above 20cm to all the way to 80cm -recall that a Realized Niche= ecological niche= abiotic components that a species need to persist and uses an array of essential resources + with interaction with other species/populations and this EITHER EXPANDS OR RESTRICTS FUNDAMENTAL NICHE depending on whether the interaction is detrimental or beneficial -so what u saw here was that the concept of realized niche focused on the fundamental niche= ecological niche without the interaction with other species so you saw how competition ( detrimental / - interaction) can wrk to restrict range of resources and env conditions used by a species Adaptive Radiation: -start with one species that give rise to many other species that exploit different environmental features such food/habitat -these diff environmental features exert selective pressures that push populations in various directions ( phenotypic divergence) -speciation occurs when there are changes in morphology, behavior and habitat preference that are the actual targets of selection which produces reproduction Isolation WHICH IS A MUST IN SPECIATION -variation btw local populations in biotic interaction can result in phenotypic divergence and therefore potentially function as the mechanism of adaptive radiation LEC13-CHAP 14 After the same resource but one is more efficient at getting it= btw 2 didd species Lotka-Volterra Lab experiments: -they used two diatom species A. formosa and S.ulna and they grew each of them independently and what they observed was that when grown alone each species kept silica at constant low level ( it uses/needs silica for the formation of its cell wall) and formed stable pop growth -but when grown together—S.ulna took up all the resources or most of the resources and only left a little concentration of resources that was below the requirements leading A. Formosa to go extinct Interspecific competition= a relationship that affects the populations of two or more species adversely (- -) common reason is due to short resource supply - there are 2 forms of interspecific completion: -Exploitation and interference - a lot of individuals broaden their foraging effortsthey can be forced to turn away from food that they select to those that are less in demand - there are 6 types of interaction in the interspecific completion: 1) Consumption= when two or more species fight over food supply that’s limited 2)Preemption= occupation of an individual of one species prevents another ind of diff species from occupation common in sessile organisms ( barnacles) 3) overgrowth= the organism of one species literally overgrows on top or over the organism of another species eg. some plants grow over other plants 4)chemical= some ind of a species release chemical growth inhibitors or toxins to inhibit or kill an ind of another specieallelopathy 5)territorial= when an organism excludes an org of another species from a specific area that its defending as its own territory it’s a behavior 6) encounter = nonterritorial meeting with an ind of another species that either has an adverse effect on 1 or both species eg. lion fights a dead deer, crocodile finds it too…both fight over it. 14.2 : Lotka Volterra:- Predicts 4 possible outcomes: Graphs a) species 1 - the population growth ( when its less than K) will increase until it reaches K. At k dN/dt ( rate of pop growth)=0 when it exceeds K then it approaches towards K by decreasing its pop size. b)( same as a for species 2) c) this is when you look at the graph for both species 1 and 2)..even though species 2 reaches its K…it is unable to stop species 1 from increase ( its approaching towards its k which is > than K2)…as it reaches K1, it drives species 2 to extinction d) – same as C reverse e) each species, tried to outgrow and outcompete the other species leading it to extinct. So when one specie is more than the other it will tries to stop growth of the other specie more than its own leading it to go extinct. And that specie wins…who wins depends on the intial densities population ( which specie is more abundant) e) each species (when abundant) tries to inhibit the growth of the other species more than its own. Eventually leading the other species to extinction. The outcome ( which specie wins) is based on the initial population densities ( which species is more) f) Neither population can achieve densities that’s capable of eliminating the other…so they inhibit their own population growth more than that of the other species Competitive exclusion principle: -complete competitors cannot coexist- they are 2 species that cannot breed with each other but they live in the same place and have the same ecological requirements -2 assumptions: they have the same exact ecological requirements + env conditions are constant - factors affecting outcomes of interspecific competition= env factors that affect survival, reproduction, growth + resource factors Nonresource factors -temp, soil, water pH, humidity, salinitynonconsumable competition they affect and influebce physiological processes and affect growth and reproduction can influence competition Env. Variability: -its advantageous to species since it allows to the competitors to temporarily coexit under constant conditions they would exclude others Multiple resources: - species competition involve multiple resources -competition for one resource influence an org ability to get other resources -eg. compete spacefood, nesting sites, ,mates etc Environmental Gradient -when the env conditions change so does the competitive ability of species (eg. if something in the env was beneficial for an organism because of the change in the same env condition its now detrimental) - the change in competitive ability of species is a result ( or occurs because) there is a change in the carrying capacity (K= which is the max amount of ind a land can sustain with unlimited resources) which is related to changes in resource base or change in physical environment that interact with resource availability) the natural environmental gradient involves covariation of multiple factors of resources and non resources such as salinity, temperature and water depth Niche: (RECALL) - ecological niche= abiotic components that a species needs in order to persist ( survive and reproduce)and uses an array (bunch) of essential resources - tis most basic/fundamental role -niche= an array of components an organism/specie exploits -fundamental niche= ecological niche that does not involve interaction with other species; there is no competitionaka physiological niche -Realized niche= ecological niche with interaction with other organisms + competition -when compression or shift in the fundamental nichecompetitive forces causes a restriction in the type of food or habitat -realized niche= sometimes due to competition it does not optimizes the conditions -fundamental niche= so in the absence of interaction with other species there is a competition releasethus expanding its niche Resource partitioning: -individuals of species that share the same habitat coexist by partition(dividing) the
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