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Ecology (ENV2410 (scientific method (general outline (1) observation,…

- - - - change 1 factor at a controlled amount w/ a control
    - - observations
  - - - complete randomization (TTCTCC)
      - randomized blocks (useful in a gradient) (e.g TC-CT-CT)
      - systematic (e.g TCTC)
- - - - generalist: although few are actually widespread, sine they are not dependent on particular habitats, they have adapted to urban environments, which have become widespread and abundant
      - specialist: are adapted to specific conditions. most have small ranges and are highly adapted to them.
      - Rapoprt's rule of range size: latitudinal range of species is small at low latitudes compared to high latitudes
        
        pattern based on sp. richness. the more species the smaller the range
        
        pattern based on climate variability- e.g tropics are more variable
    - - behavior & dispersal habits
        
        behavior
        
        niche
        
        realized niche
        
        the actual environmental range where a species lives/ reproduces
        
        can't use realised niche as a full prediction of fundamental niche (e.g cane toad)
        
        niches are dynamic. vary amongst sp. due to local adaption
        
        change
        
        specialization for one set of environmental conditions may reduce stability/ suitability for other
        
        sp. can migrate to a new fundamental niche OR sp. can stay and adapt to the change
        
        definition of behavior: how organism respond to the environment, among their species and other organisms
        
        dependent on the concept that energy is finite, and therefore energy spent on one behavior is energy not spent on another
        
        definition of evolution: how behavior influences survival & reproductive success (e.g predator avoidance or plumage)
        
        predator defense
        
        avoid detection (e.g. camouflage, nocturnalism)
        
        physical (e.g. size, thorns/horns)
        
        chemical (plant poison, and insect stings)
        
        speed/flight + extreme vigilance
        
        stressful environments
        
        can cause more flexible behaviors- tending to more generalist
        
        can cause more specific behavior- tending to specialist
        
        optimized foraging: choosing what food to eat taking into account availability in habitat and how much is needed
        
        time minimization
        
        energy maximization
        
        nutrient balance
        
        territorial behavior can occur over of food and mate availability
        
        reproduction considerations
        
        finding/attracting a mate
        
        offspring: quantity and survival
        
        parental care?
        
        mating effort + parental investment= reproductive success
        
        group living
        
        pros
        
        help in activities
        
        mate access (for some)
        
        foraging efficiency
        
        reduce predation
        
        cons
        
        loss of reproduction (competition)
        
        increase disease risk
        
        competition for food
        
        uses in management plans
        
        culling dominant males in multi-male groups to disperse a group
        
        re-location of large predators as method of pop. control could be inefficient if they are territorial
        
        animal needs in captivity- e.g active sp. may need toys
        
        K vs R selected sp.
        
        R: boom or bust breeding habits: many young, short lived, low young and adult survival. but quick maturity
        
        K: reliable breeding habits- long lived sp. w/ a few well looked after young. but late maturity
        
        dispersal
        
        types
        
        diffusion
        
        gradual spread across non broken suitable habitat
        
        jump dispersal
        
        able to spread to a suitable habitat by crossing non-suitable habitat (e.g over a stream or across the nullibor dessert)
      - abiotic
        
        scale
        
        geographical: e.g climate
        
        local: soil
        
        fundamental niche: range of abiotic factors within which a species can live and reproduce
        
        normally a gradient, but sharp boundaries can exist- e.g salt affected area near woodland
      - biotic
        
        competition (-, -)
        
        intraspecific: same sp.
        
        interspecific: different sp.
        
        interaction between 1 or mote organisms using a common resource & has an adverse effect all involved
        
        mechanisms of competition
        
        exploitation of a resource: makes it unavailable to other organisms
        
        interference: prevents other sp. gaining access to a resource (e.g. poison or using nesting sites (e.g honey bees))
        
        why does it occur?
        
        resource is short/ sparse
        
        number of individuals or amount of effort is high
        
        evidence
        
        laboratory studies: convenient, but short and often makes one sp. extinct
        
        patterns from nature: shown via negative correlations between pop characteristics of one sp. or another. but doesn't demonstrate effect sufficiently as there are other factors at play, e.g environmental suitability
        
        selection pressure considerations
        
        resource partitioning/niches. e.g darwin's finches minimize food overlap
        
        individuals in unoccupied niches/ resources have greater access to it
        
        partitioning an area: e.g. parts of an estuary/river or along a coastal cliff
        
        if competition cannot be avoided, competitive abilities are often developed
        
        predation/ herbivory (+, -)
        
        although on different scales all are important
        
        predation. 1 animal kills another for food
        
        herbivory: animal uses a plant for food- rarely kills the plant
        
        study methods
        
        field experiments (predator removal/exclusion)
        
        modelling changes: cycles of abundance, correlations & classic predator-prey model
        
        predator-prey model: prey numerous--> predetors increase --> prey declines --> predetors reduce --> prey increases
        
        in lab experiments (normally for small scale animals, e.g. protozoans): usually results in extinction of prey, unless given refuse
        
        "doomed surplus" concept: some individuals will die before reproducing, and can therefore be seen as surplus. often this is due to predators killing young, but sometimes it can be environmental conditions
        
        components of predation
        
        individual behavior
        
        search time
        
        attack rate
        
        handling time
        
        exposure/familiarity with prey type
        
        response to change in prey: functional (may seek other prey types) & pop. size may fluctuate with prey pop.
        
        subsidiary components: e.g. hearing & hunger
        
        remember prey pop. not necessarily only effected by a single predator sp.- therefore the removal of one predator may have little impact
        
        some predator spp. are a keystone sp., (a single sp. t has a great impact on a community).
        
        e.g. seastars which maintain the prey pop., without sea-stars the community became a near mono-culture of only a single muscle sp., where there was a variety of life before
        
        Case Study: Mulgara (a small desert predator) and rodents/ prey
        
        a plot was marked out, with a food bowl in the center. visitors to food were recorded. treatments over a few days: 1) fenced control (exclusion of predator), 2) picketed control (incase the mulgara were using them as perches in 1. 3) open control: normal system
        
        when predator was excluded, only a single sp. of rodent was visiting, since it was out competing the others for the food.
        
        parasitism/ parastoidism (+, -)
        
        parasitism: one organism feeds off another but rarely kills
        
        parastitoid: an insect parasites another insect, usually killing the host
        
        neutralism (0, 0)
        
        mutulism (+, +)
        
        2 types
        
        obligate
        
        rarer. close co-evolution between two sp. the two sp. depend on the other, therefore one can't survive without its partner (e.g lichen & coral)
        
        facultative
        
        interating sp. found together intermittently, but performance is better in a pop. e.g cleanerfish and pollinators
        
        often consists of a sp. and its foundation sp. where a foundation sp. is the dominant sp. e.g coral which also provides shelter for others, and has the area of attachment for zooxanthellae
        
        but there may be consequences, e.g dispersion rates must be limited to keep with partners, and may reduce survival rate- if there a fewer of one sp. may cause the other to be at risk too.
        
        case study: devils garden
        
        In return, the ants provide an amazing defense mechanism- they will viciously attack any predator that comes near and will kill any vegetation that is in competition with the tree
        
        the thorns are hollow, and provide shelter to the ants. they also provide food to the ants by having leaflet tips packed with protein and oil, as well as extra-floral nectaries (which are expensive to maintain).
        
        swollen thorns acacia and ants have a very interesting obligate mutualism. the acacias have sacrificed their thorns from playing a defensive role, to housing ants and expend extra energy to encourage them.
        
        commensalism (+, 0)
        
        1 sp. has a positive effect on another sp., but does not receive any benefit itself
        
        e.g scavenger eats a carcass left by another predator OR dung beetle using feces of other animals
        
        how to test: T1: without supposed species "benefiting", T2: without the species giving the benefit, C= mixture of sp.
        
        rarely black and white- often a continuum or judgement.
        
        ammensalism (-, 0)
        
        remember a relationship can change! e.g nurse plants start as commensalism --> competition
      - human activity
  - - - plants method
        
        quadrats/ plots
        
        transects
        
        visual records
        
        aerial
        
        remote sensing
        
        drone
      - animals factors
        
        mobility
        
        behavior
        
        aggregation
        
        changes in behavior
        
        life history
        
        large variation in abundance
      - animals
        
        sub sampling quadrat
        
        randomized points along a transect or stratified area
        
        can be fixed. for a good representation over time
        
        calculation: density= whole area * area
        
        active sampling
        
        considers life history stages
        
        e.g different depth (aquatic) in prawns, where mature prawns are deeper than young
        
        collection devices
        
        important to maintain ethical practices
        
        some sp. are trap avoiders
        
        passive (e.g pit trap) vs active (e.g. trawl net)
        
        attractant trap
        
        taxa specific traps (e.g light trap= bugs, fish bait=sp. of fish)
        
        tags for highly motile sp.
        
        capture-mark-recapture
        
        common in vertebrates
        
        2 capture periods close together, but allowing dispersal time (T1 and T2)
        
        MT2/No. caught/seen T2= MT1/Pop T1
        
        assumptions
        
        closed pop. (numbers don't change)(short period between sampling)
        
        Marked animals will mix randomly
        
        marks won't affect the animals behavior or survival
        
        mark is permanent
        
        processes
        
        1: collection, marking and release
        
        2: pop. mixes
        
        3: collection, count marks & unmarked and release
        
        multiple census'
        
        operate over a long period of time. allows examination of an open pop. and allows for change in pop. numbers
        
        photo ID individuals
        
        a non-invasive method of tagging. e.g dolphin fin shape
        
        relative abundance: collection of data to compare size without estimating the pop. size. based on trends and indices (e.g habitat). assumes sampling method is consistent. some measurements include: vocalizations & fecal counts.
      - some factors that can cause misleading evidence
        
        ignorance of life history (e.g some plants die back to a bulb seasonally- therefore if sampled at wrong time may seem like its not accounted for)
        
        some sp. are super abundant or can aggregate and thus can be over represented in a sample (often accounted for in data manipulation)
        
        ignorance of behavior. e.g noctunalism
        
        in plants ignorance of seasonality/life history can be vital to ID. e.g parts necessary for ID, e.g flowers or fruit may only occur at certain parts of the year
        
        in plants clones can be misleading if numbers are used for an indicator of health. i.e genetic diversity important
        
        hybridization can be hard to ID
        
        skill of person IDing- may cause confusion
      - plants
        
        quadrats
        
        permanent
        
        random
        
        micro
        
        point intercept
        
        tag individuals
      - soil
        
        transects with randomized points nearby
    - - absolute estimate
        
        something that is able to be counted. e.g. eggs/nest, aerial survey of a herd size
      - estimation of total density. need to extrapolate pop. mean and variance using sample mean and standard error
    - - density dependent: incorporates some restraints (carrying capacity, "K") = logarithmic growth
      - density independent: doesn't consider environmental factors= exponential growth
      - factors
        
        environmental: e.g habitat
        
        biological: e.g disease, predators and food
        
        limiting factors knowledge can be applied
        
        to increase a pop (e.g rare/endangered sp.)
        
        to reduce abundance of pest sp.
        
        manage harvastable sp sustainably
    - - demographic: the study of size and structure of pop. & change. examples of examined pop. structures are: age & gender %
      - life tables are a good representation of pop. number changes.
        can be used to make survivorship curves
        
        headings are: age (years), Number surviving, Proportion surviving, deaths in each age () & mortality rate (). *= needs to be calculated
    - - equilibrium: when death and birth rates are roughly equal
        
        pop.s that reach equilibrium are often called deterministic. pop.s still in flux are known as stochastic
        
        either birth or death rate must be density dependent
      - limiting vs regulatory factors
        
        limiting: produce a change in average/equilibrium density, e.g. new predator
        
        regulatory factor (density dependent factor): produce a % change in pop., i.e. the % mortality increases w/ increasing pop density e.g. a disease
      - extrinsic vs intrinsic
        
        extrinsic: external to pop. e.g. parasitism/predators (density dep), abiotic factors (density indep), disease
        
        intrinsic: within the pop. e.g. demographics, behavior and genetics
      - overcrowding/ self-thinning rule: density dependent intaspecific competition can be intense
        
        yield per density in a monocultured crop. at low densities, crop is large and there is a low mortality rate in the pop, when it is overcrowded, may lead to less yield as the crop becomes smaller and have a high mortality rate.
      - mortality: compensatory vs. additive interactions
        
        additive: uses the logic that an individual only dies once. a cause is attributed a number of deaths, and all totaled together to give estimate of death count
        
        compensatory mortality: recognizes that it cannot always be determined it the prey died from a single factor alone or multiple stresses. therefore it is all approximately measured
      - undercrowding and meta. pop.
        
        a large pop. may actually consist of several smaller pop.s: meta populations. may be linked one or multiple ways or isolated
        
        how to determine? tagging and letting the pop.s mix, or examining genetic material
        
        alee effect: when small pop. suffer from reduced pop. growth rates (often occurs in pop. that rely on breeding aggregation)
- - - - bare soil --> annual herb/grasses--> shrubs--> trees
      - often the decomposition of lichen and moss builds up to form soil
    - - bare rock--> lichen&moss--> grass/shrub--> tree
  - - - sometimes weeds can alter the trajectory of succession. depending on the ecosystem can decide what happens. e.g. in a forest the introduction of exotic shrubs/trees can create an exotic forest as it is still able to keep more or less the same state, but exotic grass in a forest may keep it stuck in a novel state where its normal composition/function is altered