Tutorial 2: A focus on urban ecological integrity
� Elements of diversity:Richness, abundance, evenness, graininess, allelic diversity
• Subsidized ecosystems (Sid Smith)
• The risks of estrangement from the natural world
• Green Space in the City (Draper 13)
•Even with “compact” growth, the GTA will gobble up an additional 350 km 2 by 2020 (a 23% increase)
•Following the current trend of dispersed growth will require 900 more km 2 (a 60% increase over
today)
•According to Greater Toronto Home Builders’ Association (03/02/27) "Our studies show that about
three-quarters of the buyers will be seeking ground-level single detached homes.”
•How does that statement map onto the NRTEE vision of the future: “housing densities have
increased to the point where 70% of Canadians live in some form of multiple dwelling”?
• Box 13-5 (Urban Forests)
Tutorial 6: estimating population size
� how do we know how many individuals are in a particular population?
� Relative abundance (catch per unit effort) vs. mark-recapture
� Relative abundance is not a population estimate
•“seeing” more animals does not mean a population is increasing
•“seeing” the same number of animals does not mean the population is stable
� Mark-recapture “works” on the assumption that the ratio between all animals caught (marked and
released) and those recaptured is the same as the ratio between all the animals in the population
(unknown) and those caught just once.
� Useful population estimates are accompanied by some measure of variance (SE in our case)
Draper 3: Definitions
�Ecology: population, community, biome
�Components and Structure of Ecosystems
�Tolerance (limiting factor principle = Liebig’s law of the minimum)
�Interactions: fundamental and realized niches, competition, resource partitioning and competitive
exclusion, symbiosis, gross/net primary productivity
�Responses to environmental stress: carrying capacity
�Biological evolution: genes, mutations, adaptation, differential reproduction, natural selection,
speciation, mass extinction
�Evolution, adaptation, natural selection
�Ecological succession: primary, secondary, climax community
Re-read Draper: Working with Nature (pp 91, 88, 85)
�Six key features of ecosystems: interdependence, diversity, resilience, adaptability, unpredictability,
limits
�Need to acknowledge and accept the reality of ecological limits
�Achieving sustainability means shifting our emphasis from “managing resources” to “managing
ourselves”
� Reducing use of matter and energy
� Shifting to renewable energy sources
� Reducing waste generation
� Preventing pollution (rather than trying to ameliorate it after the fact)
Ecosystem structure (lectures 27-29)
1. Hierarchical: complex and adaptive (Fig. 3-4)
2. An environment of some spatial complexity (microclimates) with interactions between the abiotic and
biological communities (e.g. nutrient cycling)
3. An interacting biotic community - populations of plants, animals and microbes - bacteria, fungi
(predation, competition, symbiosis)
4. Between the boundaries separating ecosystems (lake-beach or forest-meadow): ecotones.
5. Group terrestrial ecosystems of a particular region into landscapes (or biomes)
6. Persist without external subsidies of energy, nutrients (self-sustaining).
Terrestrial/aquatic continuum
�Predominant biomass in forests is in plants (the bottom of the food web)
�The predominant biomass in aquatic systems is in fish/mammals (oceans) at the top of the food chain
�Something significantly different is going on in these different systems!
� Function of organism size/turnover rate
� Disturbance regime
�In between these two extremes are grassland/savannah systems where the predominant constituents of
biomass are the herbivores (grazers like buffalo, antelope, etc.), the “middle” of the foodweb
Ecosystem structure
Interactions between organisms and environment
� Tolerance ranges of individuals/populations
� Liebig’s law of the minimum
� Multi-dimensional niche (fundamental vs realized)
� Acclimation (individuals)/Adaptation (genetic/populations)
� Grain or patchiness
� Generalists and specialists
Interactions among populations
� Taxonomic/structural characteristics
� Trophic elements (energy flow/nutrient cycling/foodwebs) and predator-prey relationships
� Energy flow (thermodynamics)
� “Non-feeding’ relationships (competition – inter/intra - and energy optimization; territoriality, larval life
history stages; symbiosis: mutualism, commensalism, parasitism)
� Producers/Consumers; autotrophs/heterotrophs; decomposers
Ecosystems: population dynamics, (lectures 28-31)
�Eruptive (Malthusian or J) and logistic (S) growth
�Generalist, Malthusian, density-independent or r-selected vs specialist, logistic, density dependent or Kselected life history strategies
�The role of time (ecological, evolutionary) and disturbance
�How do biotic & abiotic factors come together to create self-sustaining ecosystems? Trophic
relationships: Bottom-up and top-down population regulation, regulation of plant community composition
by herbivores, the importance of predators, predator restoration. (Yellowstone), exploitative interactions:
predators, parasites, parasitoids, pathogens �Case studies of St. Mathews Island, Anticosti,
NewfoundIand, Isle Royale, plants/herbivore/predator, (predator satiation, herding, crypticity, chemistry),
ploy/counterploy
�The nature of disturbance and time (Mt St. Helens vs Iceland, fire in Yellowstone vs fire
California/Mexico vs. the stump barrens, the Sonoran)
�Succession
�Complex interactions between abiotic and biotic factors or among biotic factors act to ‘select’ the
ecosystem that persists. (Savannah landscapes)
�Ecosystems as dynamic, non-equilibrium systems – they persist even as they change
Ecosystems and evolutionary timescales (lectures 32-33)
� Adaptation and fitness
� Keystone/foundation species
� indirect effects
� sea otter and kelp forest ecosystems
� sea stars (Pisaster ochraceus) and rocky intertidal ecosystems
� While predation, competition and various symbiont interactions are important regulating mechanisms in
ecological time, no predator, prey, competitor or symbiont will be passive in evolutionary time (ploy –
counterploy/co-evolution)
� predation as a long-term selective force
� parasitoid fly: Arachnidomyia lindae
� tri-trophic interactions (plants, herbivores and predators) male scarlet tanagers/goldfinches
� pollination mutualisms (bird/insects/etc.- flowers)
�The pressures on competitors vs predators/prey vs symbionts may be different . . . but the outcome is
the same: Individuals with various adaptations that promote reproduction (and the number of offspring
produced) will come to dominate the population
� Individuals without these adaptations are likely to disappear (eventually).
�This is what we mean by “survival of the fittest”
� Where “fitness” is defined by the number of offspring particular individuals in a population produce.
Our long-term survival depends more on evolutionary as opposed to ecological factors ( i.e. our genetic
ability to cope with the unforeseen).
Anthropogenic changes in land use (e.g. forestry, agriculture, urbanization) change environments:
� making them less “predictable”
� better suited to opportunistic r-strategists (rats, cockroaches, flies, pigeons, starlings, dandelions)
� less hospitable to K-strategists (oak and maple trees, hawks and owls, butterflies and a host of bird
species many urban dwellers have never seen)
� we may be ok now but what are the implications for the sustainability of natural capital and our ability
to adapt to an unknown future?
Genetic diversity: the driver of evolutionary change (lectures 34-36)
�Traits, genes, gene pools, differentiation, genetic variation, speciation (Section 5.2, KR #9; Draper 8890 (III), 85-87 II)
�Hierarchy of DNA, genes (alleles), chromosomes, chromatin �nucleotides:
• A-C, G-T, 3-nucleotide “codons,”64-word genetic language (words for start, stop + specific amino acids
– constituents of proteins); universality of the genetic code
�DNA/RNA, translation, transcription
�Alleles, mutation
�Genotype, phenotype/dominant, recessive/homozygous, heterozygous (the case of sickle cell anemia)
�Gene expression
�Differentiation
Natural Selection
�Fitness (# copies of genes a particular individual puts into the next generation)
�If individuals with different genotypes have different probabilities of survival or if they produce different
numbers of offspring or both: those “fitter” genotypes will increase in frequency at the expense of others.
Micro/macro evolution
Evolution as heritable changes in gene frequency (the peppered moth/sickle cell anemia case studies)
• a simple change in frequency = microevolution (the peppered moth example, human blood groups, ssa)
• sufficient change to lead to speciation = macro (the Ursus examples, 3-10/3-6; Fig 5-10, KR#9 foxes)
• molecular clocks
• natural selection as a mechanism for changes in allele frequency (stabilizing, directional, disruptive
selection, Darwin’s finches)
• other evolutionary mechanisms: genetic drift, sexual selection, genetic bottlenecking and founder
effects
•Sources of genetic variability
�Mutation (spontaneous and induced); Cross-over (mitosis, meiosis) Independent assortment
(8,388,608); Random fertilization (70,368, 744, 177,644); transposons (jumping genetic elements
antibiotic resistance, • E. coli 0157 Flu)
�Pleiotropy/Epistasis
�Genetic technologies
�Genetic diversity = allelic diversity
Elements of conservation ecology
�How many species are on Earth (10 million)?
�Minimum Viable Populations
� 50 breeding pairs in a contiguous gene pool/500 individuals
� statistically “immune” to genetic drift for about 100 years
�Small populations can lack genetic diversity and consequently adaptability or reproductive viability
� founder effects, genetic/demographic bottlenecks, genetic drift, inbreeding all increase the likelihood
that recessive, deleterious alleles (usually masked in outbreeding populations) will be expressed, leading
to reduced fitness in the population
� Genetic load (hemophilia in royal families of Europe)
�5 mass extinction events
� Current extinction rates likely herald a 6th extinction event
� Reasons for species losses (habitat destruction exotic invasions, cverharvesting,
climate change)
�Why conserve biodiversity (utilitarian: natural capital; intrinsic: ethical)?
�What should we conserve? (approaches for charismatic megafauna, endemics, sparsely distributed
species, migratory species)
�How do we conserve species? (in situ/ex situ)
�The role of habitat conservation vs species conservation
Elements of conservation ecology
�Island biogeography
� Smaller islands contain fewer species than larger islands
� More distant islands contain fewer species than islands closer to “mainland” source populations
� Species/area curves
�Minimum viable areas (mva)
�Role for corridors in linking areas that by themselves are too small to maintain extant genetic diversity
(Y2Y, A2A)
�“Metapopulations”
Draper Chp 12
�Importance of biodiversity (utilitarian vs intrinsic)
�Threats to biodiversity (habitat disruption/fragmentation; climate change, overharvesting, exotic
invasives)
�Endangered species/endangered spaces
�Envirofocus 12 (Grizzlies and humans in Banff)
�Ecological integrity/ecosystem management
�In situ/ex situ conservation