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chapter 53 and 54 - Coggle Diagram

- - - - density is number of individuals per unit area/colume ( number of oak trees per kilometer
      - dispersion: the pattern of spacing among individuals within population boundries
      - Density (dynamic perspective)
        
        although you can count individual organisms if they are big enough most times its impossible or impractical to count
        
        ecologist use several sampling techniques to predict population size ( count trees in random100x100m plots calculate avg density of plots and extend to the entire area to calculate total density and population, works well with fairly homogeneous habitats)
        
        ecologists can also estimate density based on number of nests, burrows, tracks etc.
        
        mark and recapture method to track population size ( indiviuals are tagged marked and released back int the wild by assuming the tagged individuals have a good chance to be recaptured you can calculate population size)
        
        N=sn/x (N estimated population size, x number of marked individuals captured in second sampling, n toatal number of animals capture in second sampling, s individuals marked and released during first sampling
        
        density can increase or decrease as individuals are added or removed from population
        
        immigration and birth: adds animals to population
        
        emmigration removes animals from a population
        
        even though birth and death effect population density so can emmigration ( large parts of a population may come from another like immigration)
        
        emmigraetion can not only reduce one population but also establish new populations in a favorable habitat
    - - spacing of individuals can differ substantially using these spacing patterns we can have some insights on biotic and abiotic factors that affect individuals of the population
      - Clumped: in which individuals are bunched up in patches animals may clumo toether where there are favorable conditions (mushrooms clump on top of a rotten log, or sea stars clumping where food is abundant)
      - uniform: even spacing between organisms that can occur due to territorialism or in plants case toxins that kill surrounding plants
      - Random: typically occurs when organisms cant control where they p like flowers happens when there are lack of attracting/ repelling forces among individuals
    - - Biotic and Abotic factors that affect desnsity and dispersion can also effect characteristics of populations (birth death and migration rate)
      - Demography is the study of key characteristics of population and how they change over time
      - life tables
        
        summaries survival and reproductive rates of individuals in certain age groups
        
        researchers often follow a group of individuals of the same age, from birth to death (cohort)
        
        building life table requires determining what portion of the cohort survive from one age group to the next ( also important to track the amount of kids birthed by the females of each age group)
        
        population is viewed in terms of females giving rise to other females
    - - survival rate data of a a life table represented graphically
      - a straight line means a constant rate of death regardless of age
      - Types of surivorship curves
        
        Type one survivor ship curve most offspring die of old age common among humans and large mammals (low offspring count but extensive care to offspring)
        
        2 offspring dies during any time (straight line) intermediate happens in belding ground squirrels some other rodents and many invertebrates
        
        Type 3: line that dips straight away most deaths during child hood ( early period of die off, flattens later after period of die off) common with animals with a lot of offspring but provide little to no care for them
        
        some animals show complicated patterns like birds (die off in childhood then dying off constantly in adult hood) crabs show a stair stepped curve (higher mortality rate while molting lower when exoskeleton is hard)
      - in populations with low levels of immigration and emigration, survivorship is one out of 2 key factors when determining changes in population size
    - - ig nore males because only females can produce offspring
      - simplest way to measure reproductive pattern of a population is identify how it varies with number of females and teir ages
      - can count females by literally counting, mark or recapture, or genetic profile to determine the amount of breeding females and how much offspring they have
      - reproductive output for birds and mammals typically measured as avg number of female offspring produced by females in a given age group
      - age specific reproductive vary wildly between species ( squirrels have litter of 2-6 young once a year for less than a decade, oak tree drop thousands of acorns each year for decades/centuries)
      - High reproductive rate does not lead to rapid growth unless conditions are ideal
  - - - under ideal conditions poupulation wil increase with immigration and birth and decrease with deaths and emmigration (no external limit on resource gathering and reproduction)
      - we can use a mathematical equation ( ignoring emmigration and emmigration)
      - change in population size, divided by time interval associated with life spam/ generation time of a species = the number of births -the number of deaths (delta N over delta t= B-D
      - population ecologists often are most interested in changes in population size individuals added or subtracted from population over a given interval R ( difference between # of biths and deaths)
      - R = b=B-D delta N divided by delta t is R
      - per capita is r times delta 2
      - final equation is delta N over delta T = r subscriot delta t times N
      - You can use differential calculus to express instantaneous
        rate of growth (t gets smaller)
    - - Under ideal conditions exponential growth occurs
      - dN over dt is the population in that moment this equals population size times r which is the intrinsic rate of increase
      - a population that grows exponentially makes a J shaped graph
      - even though the per capita population growth is constant the graph makes a J shape because the offspring of an animal has offspring
      - populations with lower intrinsic rate of incresase grow slower than those with higher r value because population increase irate is larger
      - J shaped curves can come from introduction of species to new environment, or after a catastrophic event that wipes out most of a species and is re rebounding
      - elephants were protected from hunting and their population rose to the point they ate all the grass for the other animals so females were given birth control
  - - - in logistic population growth model r decreases as N increase
      - per capita rate of population growth approaches zero as population approaches k
      - k-n is how much more individuals the environment can support
      - K-N all over K is the fraction of K available for population growth
      - if N is small compared to K then the fraction of K available for population growth is close to one (
      - when N is large and resources are scarce than (K-N)/K is close to 0 so not alot of population growth
      - when graphed produces S shape (rapid increase at first then level out
    - - in labs small organisms like paramecium beetles and crustatians they follow the S shape well
      - How ever in nature species rarely match the curve perfectly (daphnia over shoot carrying capacity, make babies faster than anything dies, since they are already on the way they only die after they are born)
      - in reality there is a delay before negative effects of increasing population are seen ( low food means reproduction will go down eventually, but females may use their last energy to continue reproducing for a bit, over shooting K temporarily)
      - Some populations oscillate on the graph carrying capacity so much its hard to define K
      - the logistic model helps us think about how population grows and build more complex models. (important for predicting how rapidly populations will grow after its reduced to small size)
      - this helps us estimate sustainable harvest rates for animals, biologists also use it to estimate the critical size at which populations may become extinct if they become lower)
  - - - 3 key components of organisms life history
        
        when reproduction begins
        
        how often it reproduces
        
        how much offspring it produces per reproductive episode
      - the idea of evolution accounting for the diversity of life presents it self in the broad range of these life history characteristics in nature ( a turtle may start laying eggs in 30 years where ass salmon wait 3-4 before spawning)
      - semelparity: have one big bang and die like salmon (Ex coho salmon salmon goes out to ocean for a few years, matures and returns back to stream to spawn))
      - agaves are also semelparious: agaves grow for years in poor soil and unpredictable rainfall, once its unusually wet it sends up a large flowering stalk releases its seeds and dies ( life history is adapted to desserts harsh environment)
      - iteroparity: can reproduce more than once in their life (dogs, cats, humans atc)
      - species also vary in how much offspring is produced, rhinons only have one calf, while frogs have thousands
      - species that half small amount of offspring may care for young more than an animal that has 1000s
    - - No organism can make thousands of offspring and take care of all of them as well as a white rhino does with one calf
      - there is a trade off between number of offspring and number of resources a parent can give to each offspring ( happens organisms do not unlimited resources)
      - as parents invest energy into reproducing or giving kids food that means there is less food for the parents making survival suffer
      - red deer that reproduce in a certain summer were mor likely to die the next winter than females who didnt
      - Caring for larger amount of children leads to higher chances of parents dying in kestrels
      - selective pressure also influence trade offs between size and amount of offspring ( low survival chance= more kids, in plants smaller seeds= higher chance of seed establishment since it can be carried by wind farther)
      - high predations can also lead to many off spring (like mice, quail, sardines, etc)
      - in other organisms more investment of the parent= skyrocketed chance for offspring to survive (brazil nut/walnut trees, send out seeds with food so they increase chance of seedlings becoming established)
      - In primate, low offspring, first few years of life are important for fitness, parents spend more time with them.
      - vartiations of life histories ca be categorized as R selection or K selction
        
        individuals that cranked r to the max have lots of babies with many dying they are R selected and typically have a type 3 survival curve
        
        Animals that are k selcted focus on the survival of young there for they selected to have populations near K and have a type 1 survivorship curve
  - - - if emmigration and immigration rates are equal than population only grows if birth rate exceeds death rate
      - a birth rate/ death rate that doesn't change based on density is density indepedent (grass that dies when drought stress uncovers roots)
      - a birth rate or death rate that does change with population density is called density dependent ( as population goes up food becomes more scarce)
      - combonation of density dependent reproduction and density independent mortality can lead to a stop in population growth
      - density independent factors can increase or decrease populations, but not consistently, only density dependent factors can
      - populations can be regulated when one or more density dependent factors cause population increase or decrease
    - - without some sort of negative feedback a population would never stop growing
      - at large population sizes negative feedback is provided by density dependent factors ( stops polation growth by either reducing birth rate or increasing death rate)
      - as kelp density levels increase their death rate also increase because there was nowhere to hide
    - - competition for resources: more animal=less resources to go around
      - Disease: the higher the population density= easier for a disease to spread
      - Territoriality: animals compete for space limiting population
      - intrinsic factors= factors that operate at the individual organism (agressive interactions and hormonal changes in mice that delay sexual maturation)
      - Toxic waste: fish in aquarium, more fish= more ammonia=less fish over time
    - - population fluctuations are called population dynamics
      - fluctuatuins in one species can affect another (fluctuations in fish can affect populations that feed on fish, like seagull)
      - study of population dynamics focuses on biotic and abiotic factors that cause popuation fluctuations
      - Stability and Fluctuation
        
        large animals can also experience fluctuations in the long term (moose getting hunted by wolves while both were isolated from immigration and emigration)
        
        harsh weather kills moose reducing population size, when food is available with mild weather population goes back up, when moose population goes up, increase in predators and ticks/parasite lowers population
      - Population cycles
        
        many populations have random fluctuations, but some have regular boom and bust cycles
        
        snow shoe hares have 10 year boom and busts cycles caused by food shortage or predator pre interactions, (other predator numbers rise and kill them)
        
        snowshoe hares reduce i numbers when they are over exploited by predators
        
        emmigration and immigration are important when dealing with multiple linked local population (meta population)
        
        , A butterfly found in 500 meadows across aland islands in finland has potential to live in around 4000 patches of habitable land, so new populations can appear while old ones die constanlty shifting the patches they live in constantly
        
        an individuals ability to move between populations can vary with genetics (butterflies heterozygous for a gene Pgi flew farther than homozygotes)
        
        Meta population concept helps ecologists understand population dynamics and geneflow in patchy habitats
  - - - has grwon explosively over the last 4 centuries
      - the time it took for the population to double in size was 200 in 1650 and only 45 in 1930, our population has grown even faster than exponential growth
    - - population dynamics very from region to region, a stable regional population=birth rate=death rate (disregarding the effects of immigration and emigration).
      - a change from high birth and death rates to low birth and death is called a demographic trasition
      - demographic transition tends to follow quality of life changes and industralization
      - birth rates declined alot in china due to a strict one chld policy (birth rates decline more variably)
      - in many industrialized countries like japan, canada, and the u.s reproductive rates are below replacement level (population will decline if there is no immigration or increased birth rate)
    - - relative number of individuals of each age in the population
      - zambia has a bottom skewed pyramid meaning there are more kids than adult, if kids grow up there can be an explosive growth
      - u.s has an even population pyramid
      - italy has a small base this means there aren't many kids and can indicate a population decrease
      - age structure diagrams cannot only predict population growth trends, but also show social conditions (italy a small number of kids have to support a large number of boomer's retirement)
    - - Life expectancy reflects quality of life for children
      - if infant mortality is high parent might have more children to ensure some reach adulthood
      - Global life expectancy has been increasing but some regions facing social upheval or disease might see life expectancy drop
    - - first carrying capacity for humans was 13 billion, while others say as little as 1b or as much as 1000b
      - carrying capacity is difficult to estimate and scientist use different methods to estimate it
      - limits on human population size
        
        ecological foot prints helps us estimate how much land is required to maintain ones life (resources need to produce and to get rid of waste)
        
        if you add up all the ecologically productive land on earth and divide it to every human on earth each human only gets 1.7 gha (global hectaacre)
        
        a typical ecological footprint of a person in the U.S is 8 gha, globally average is 2.7 gha per person
        
        A person in the U.S, canada, or norway consumes 30 times times the energy that a person in central africa does
        
        fossil fuels are the source of 80% of the energy in developed countries, unsistainble reliance on fossil fuels lead to the changing of earths climate and increasing amount of waste humans produce
      - combination of resource use per person and population density determines our global ecological footprint
      - alot of human populations demands have exceeded both local and regional supplies , alot of people
      - human population may be limited by earths ability to absorb wastes, (future generations of humans carrying capacity might be lower
      - Technology has substantially increase earths carrying capacity, but no population will grow indefinetely, will we attain zero population growth through laws or increase mortality due to lack of resources, plagues, war and environmental degradation
- - - - competition: -/- bad for both organisms
      - predation: +/- interactoin positive for predators negative for prey
      - herbivory
      - paratism
      - mutsualism: +/+ good for both organisms
      - commensalism
    - - -/- interaction occurs when individuals of different species use the same resource (limits survival of both individuals), can also occur within the same species
      - competitive exclusion: to different species that use the same limiting resource, they cannot coexist permanently without disturbance (leads to elimination of inferior competetor
    - - competition for limited resources can cause evolutionary change in populations like niche (when a lizard hunts what temperature it likes what branches it uses), how it fits into an ecosystem
      - 2 species cannot coexist if their niches are identical however, if they are different they can (species using a different set of resources, or same resources in different times of year)
      - similar species can coexist with different niches (resource partitioning
      - as a result of competition a species fundamental niche (niche potentially occupied by a species) is different from their realized niche (portion of fundamental niche it actually occupies
      - ecologist identify fundamental niche by testing a range of conditions a species grows and reproduces in absence of predators, then adding a competitor to see if it limits the species potential niche
      - ecologist also test whether or not a potential pcompetitor limits a species by removing it and seeing if the first species moves into the new available spaec
      - animals can also parition their niches in time ( A. russatus is naturally nocturnal, however it must override its natural clock in the presence of A. cabirinus so they can coexist)
    - - Character displacement
        
        allopatric populations are morphologically different and use similar resources while, sympatric species have different body structures and resources they use (diverge more in sympatric then allopatric populations, character displacement)
        
        beak length in allopatric population is similar, while sympatric they differ greatly (result of competition and using different resources to coexist)
      - Exploitation
        
        +/- interaction (one organism benefits the other is negatively impacted
        
        predation:an individual of one species kills another (eating and avoiding being eaten are prerequisites to reproductive sucess
        
        most predators have sharp senses to find prey (pit viper sense based on thermal sensors), claws, fangs and poison are also adaptations to subdue prey.
        
        potential prey have defensive adaptations to avoid being eaten, (hiding, deeing, herds, schools, toxins, and chemical defenses)
        
        animals with effective chemical defense are bright colors (aposematic coloration. waring coloration) , predators avoid bright colored prey cryptic coloration=camouflage
        
        some prey escape predators by looking similar to other species (batesian mimicry) a harmless species imitates a harmful one (hawmoth larvae puff up, to look like a snake)
        
        mullerian mimicry: when 2 or more species have a similar apperance predators learn to not eat them (yellow jacket and cuckoo bee resemble each other and are both unpalatable)
        
        mimic octopus can mimic the movement and apperance of more than a dozen marine animals, this lets it get close to prey ( if it pretends to be a crab it can get close to other crabs to eat)
    - - +/- interaction an herbivore eats a plant
      - most herbivores are invertebraetes (grasshoppers, caterpillars, beetles, etc)
      - herbivores have specialized adaptations to distiguish between plants based on toxicity or nutritional value (chemical sensors on herbivore insects, goats and sense of smell)
      - plants defend them selves with toxins, spines, thorns etc, compounds that arent toxic to humans but unpalatable for herbivore, are the reasons for the flavors of peppermint cinnamon etc.
    - - +/- interaction one organism the parasites gets nourishment from a host
      - endoparasite: feed on the inside of host (tape worms)
      - ectoparasites: parasites that feed on surface of host (ticks)
      - 1/3rd of all species on earth are parasites, many parasites haev complex life cycles in multiple hosts (blood fluke infects 200million people globally and needs 2 hosts at different times in its development)
      - parasites can greatly affect the survival, reproduction and density of their host population
    - - +/0 or +/+ interactions
      - mutualism
        
        both individuals benefit
        
        common in nature
        
        animals that pollinate flowers or micro organisms in ruminant of herbivores are examples of mutualism
        
        in some mutualisms each individuals depend on each other like acacia ant (ants attack anything that touches tree, and eat nectar from tree)
        
        both incur costs and both reap benefits
      - Commentialism
        
        +/0 interaction
        
        common in nature
        
        many wild flowers grow best in low light environments like shade (depend on the trees above them to provide their dim habitat and the flowers do not affect the reproduction or survival of the trees), results in a +/0 interaction with trees
        
        egrets feed on insects flushed out by herbivores, so they follow them, mean while herbivore are unaffected by the birds
        
        some commentialisms can turn into mutualisms like when birds might remove parasites from herbivores or birds warn herbivores of a predators approach
        
        positive interactions have major effects on ecological communities (juncus shades soil to reduce evaporation and lower salt concentration in soil and increase oxygen levels for other plants
  - - - different kinds of organisms that make up a community
      - 2 components species richness (# of different species in community) relative abundance (proportion of each species in a community)
      - species richness can be the same in too areas but the species abundance can greatly differ ( 2 forests with 4 different trees species, may have different dominating species)
      - ecologists use many tools to compare species diversity (shannon diversity index)
      - determining number and relative abundance of a community can be hard if you cant get a large enough sample size or you cant identify a species morphologically
      - it is also hard to determine diversity of microorganisms and deep sea creatures, ecologist use molecular tools to help determine microbial diversity
    - - ecologist manipulate diversity in expiremental communities in nature and in labs
      - increased diversity can lead to increased productivity and stability of communities
      - higher density communities are generally more productive and can recover from environmental stresses better
      - higher density communities are also more resistant to introduced species (organism humans move outside of natural range)
      - when scientist introduce tunicates into expiremental communties the tunicates were 4 times more likely to survive in less diverse communities than higher diversity ones
    - - structure and dynamics of a community rely on feeding relation ships between organisms (tropic structure of community)
      - transfer of chemical energy goes from plants to herbivore, predators, secondary, tertiary, quartenary consumers and decomposer, (foodchain)
      - position of an organism in food chain is called trophic level
    - - food chain isnt a isolated unit, instead it makes a food web
      - community arrows link species according to who eats whom
      - a given species may appear in more than one tropic level (krill feed on phytoplankton as well as other grazing zoo plankton, non exclusive consumers)
      - you can simplify food webs by either only looking at a portion of the community or grouping similar organisms into one group like over 100 species of phytoplankton being primary producers in the food web
    - - food chains are limited to typically 7 links
      - energetic hypothesis: only 10 percent off energy stored in organic matter at each level is converted to organic matter in the next energy level
      - 100kg of plant can support 10kg of herbivore biomass and 2kg of carnivore biomass
      - food chains should be longer in habitats that are characterized by higher photosynthetic production (more energy stored in primary producers)
      - carnivores tend to be larger at higher trophic levels, size of the carnivore expands upper limit on the size of food it can take into its mouth, (typically large carnivores cannot sustain themselves on small food items, so they need to get bigger to catch bigger prey)
    - - certain species play large impacts because they are abundant or play a large role in community dynamics
      - foundation species: have strong affects on their commnunites due to numbers/ abundance (trees, shrubs some marine algae etc, they provide a habitat or food)
      - keystone species: are not usually abudant in community but they exert strong control on commmunity via their pivotal roles (the sea star regulates an abundance of competetively dominant species called mussels there fore maintaining commnunity divercity
      - ecosystem engineers: change the environment (beavers)
    - - bottom up the abundance of organisms is limited by lower trophic leveles more plants= more herbivoroe= more predators)
      - Top down control (abundance of organisms are controlled by consumers at higher levels (predators limit herbivores, herbivores limit grass, killer whales killling sea otters)
      - ecologists have applied top down control to improve water quality in lakes (ecologist removed fish from lakes to decrease predation of zooplankton so zoo plankton can keep ciano bacteria in check)
  - - - high level of disturbance can either be from high frequency or high intensity disturbance
      - low level disturbances are either low frequency or low intensity disturbances
      - intermediate disturbance hypothesis: moderate levels of disturbance foster higher levels of diversity than high or low levels (too high can kill too much species, too low can make competitively dominant species take over, over less competitive ones)
      - low level and high level disturbances are important for diversity too (can make patches of different habitats across a landscape, fires also help start new generations for certain trees, lodge pole cones stay closed until exposed to immense heat)
      - trees in yellow stone liked fires but humans preventing fires stocked up fuel for bigger fires that trees could not handle
    - - changes in composition of terrestrial communities are most apparrent after severe disturbance (volcanic eruption, glacier stirp away all existing vegetation)
      - ecological succession: disturbed area is colonized by variety of species, which are the replaced by other species that are again replaced by other species
      - when ecological succession happens for the first time in a virtually lifeless area like a new volcanic island, its called primary succession
      - early and later species may be linked by one of 3 processes
        
        early species can make it easier for later species to go into the habitat by making environment more habitable
        
        early species may inhibit establishment of later pecies
        
        early species may be completely independent of later species
      - secondary succession: recolonization of an area after a major disturbance wipes out most but not all organisms in a community
      - Human disturbance
        
        some of the strongest disturbances are from human activities
        
        agriculture has disrupted the grasslands of the u.s
        
        rainforests are dissappering from humans chopping tem down for wood
        
        humans also destroy marine environments by scraping coral and other life on the sea floor with weighted nets (trawling)
        
        disturbance by human activities is often severe, and reduces diversity in many communities
  - - - life diversity is generally more diverse in the tropics (6.6ha has 711 species of trees, while in michigan there is only 10-15 tree species)
      - 2 key factors affect latitidinal gradients of species richness
        
        evolutionary history (series of speciation events may lead to increased species richness in community), tropic communities are typically older than temperate and polar ones
        
        clmate: sunlight and rain which are both high in the tropics (evapotranspiration: evaporation of water from from soil and plants, is high hot areas with lots of rainfall)
        
        vertebrate species richness increase as evapotranspiration goes up
      - Area affects
        
        if all factors are equal the larger an area the more species it has
        
        larger areas offer greater habitat/microhabitat diversity
      - Island equilibrium model
        
        islands provide excellent opportunities to study the effects of area and other factors on communities due to small size and isolation
        
        as more species occupy an island the lower change of immigration because any animal that immigrates is unlikely to represent a role that isnt already present
        
        the higher the species on an island the higher chance of extintion due to competitive exclusion
        
        small islands have lower immigration rates since they harder to see than large ones
        
        small islands have higher extinction rates because there is lower resources and less diverse habitats
        
        islands closer to mainland have lower extinction rates than islands farther away because animals from the mainland can immigrate to replace the declining species
        
        an equilibrium will eventually be reached where rate of immigration=rate of species extinction
        
        number of species at equilibrium should correlate to the size of the island and its distance from the mainland
        
        even though number of species should equalize at a certain level immigration and extintion continue so species composition could change over time
        
        scientiststs identified all arthropods on an island and found that more species were on the bigger islands closer to the mainland, then they killed every arthropod by fumigating the island, after wards they saw the # of arthropod species went back over time to pre fumigation levels and the island closest to the mainland recovered first, while the island farthest from the mainland was the last to recover. while controls were not fumigated remained approximately constant during study
  - - - disease can wipe virutally wipe off species ( disease wiped out staghorn coral)
      - corals provide habitat for lobsters, snappers, etc (low corals=lots of algae= change in dominant fish species=when corals topppel reef structure disappears and diversity gets lower)
      - disease can also alter community structure in terrestrial ecosystem ( SOD killed alot of trees, so bird abundance of 5 species got lower)
    - - zoonotic pathogens: pathogens transferred from animals to humans (3/4 of emerging human diseases and many of the most devastating established diseased are caused by zoonotic pathogens)
      - vector: intermediate species (parasites spread zoonotic diseases, lice, mosquitoes, ticks, etc)
      - identifying host communities and vectors for a pathogen can help prevent illness (identifying the shrew as a important host for lyme disease, provides info that may be used to control the hosts responsible for spread of diseases)
      - ecologists use knowledge of community reactions to track spread of zoonotic diseases. (ecologists are studying avian flu by trapping and testing migrating and resident birds )
      - control programs of quarantining domestic birds or monitor their transport can be difficult for strains of avian flu that spread naturally through movements of wild birds)
      - efforts to stop avian flu spread have not been successful
      - human activities like climate change ad destruction of habitats can increase the risk of zoonotic disease by letting animal carriers increase contact with people
      - humans are spreading pathogens around the world at unprecedented rates
      - pathogens that cause human diseases are spread by global movements of people
      - 2 new corona viruses have caused new infections in humans (SARS, transfer of corona virus SARS-CoV from bats to cats to humans, MERS transfer of coronavirus MERS-CoV from camels to humans)
      - to control pathogens and diseases they cause, scientists need an ecosystem perspective, and knowledge of how pathogens interact with other species and all aspects of their environment