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Computational Ecology Introduction to Ecological
Science Sonny Bleicher Ph.D.
Ecos Logos
Defining Ecology
• Interactions: • Organisms:
• Plants
• Animals:• Bacteria
• Fungi
• Invertebrates
• Vertebrates
• The physical environment:• Air:
• Gasses
• Water Vapor
• Water: • H2O
• Ions
• Earth:• Minerals
• Ground water
• Dissolved organic matter
But first what is a living organism?
• Reproduction
• Growth
• Metabolism
• Death
Scales of Study
From the individual to the biome
• The individual
Not a traditional, however at the forefront of ecological research
• Micro-scale genetic makeup and epigenetics affecting personality and choices of individuals:• Should an individual take risk (be
bold) or avoid risk? • Is any mate a good mate for any
individual? • Should an individual seed germinate
now, or wait for better conditions?
The population
A group of individuals of the same species that inhabit the same space.
• How many individuals cans the space(and resources) sustain?
• Demographics (distribution of individuals between the sexes, age classes).
• Life tradeoffs (where to invest energy in reproductions (cost of offspring, parental care, and time of reproduction)
The Community
A number of populations of difference species interacting in the same space
• Interaction types :• Predation (+, -) (and parasitism)
• Competition (-,-)
• Neutralism (0,0) (not fully an interaction)
• Commensalism (+,0)
• Amesalism (-,0)
• Mutualism (+,+) (can also be referred to as symbiosis if persistent over long time)
The ecosystem
A community of organisms interacting with each other and with their environment such that energy is exchanged and system-level processes, such as the cycling of elements, emerge.
• Focus predominantly on the movement of the non-biological elements, needed to sustain life, movement in the environment:• Water
• Energy
• Carbon
• Nitrogen
• Phosphorus
Ecosystem (continued)
Ecosystem Services
• Ecosystem ecologists measure system health using measures of biological output, usually translated into human economic value:• Biomass (lumber, crops, food).
• Gas production, and sequestration (oxygenation of air, carbon sequestration and fixing).
• System regeneration (water filtration, pollutant sequestration and absorbent).
• Climate regulation
Biomes:
The Biome: Macro-Ecology
• Study of the effects of climatic conditions on biological communities and ecosystems.
• A study of convergent systems on a global scale.
Temporal Scales
Scale Times
Individuals Minutes-Days
Populations Years-Decades (occasionally days )
Communities Years – Centuries
Ecosystems-Biomes Centuries-Millenia
Spatial Scale
Micro-Habitat Habitat
Ecological Niche Biome
Virtual Scale?
The Three Ecologists
The Theoretician – Modeler
• Using observations and computations to distill the laws by which ecological interactions occur.
• Based on the derived models, making predictions and designing management plans for resources
The Empirical Ecologist
• Using the natural conditions in the field to test the modeler’s laws and make observations.
The Conservation Ecologist
• Using the theories and management plans, together with the field experiment of the empiricist to manage the biological resources and diversity.
Approaching Science:World Views (Research Programs, Lakatos)
Ecological Research Programs
History of Life
• All organisms evolved from common ancestors.
• Tracing back the ancestors, and identifying relative relatedness can shed light on how species interact and what are the conservation needs of a species.
Tools:
• Cladistics
• Phylogenies
• Genetic analysis
Ecological Research Programs
Diversity
• Systems with richer diversity are more stable.
• Higher diversity means system stability.
• High species richness allows for less invasion by alien species.
Tools
• Taxonomy
• Genetic diversity testing (microbial)
• Diversity indices
• Diversity extrapolation and estimation models
Ecological Research Programs
Optimization • Competition for resources (energy, safety,
mates) drives all interactions in nature.
• All interacting species are in a constant armament race against each other, the losers go extinct.
• Thus, every physical and behavioural trait must have (or have had) biological benefit, and the cost of it must not be grater than that of the benefits to the current living organisms
The Red Queen responds: "Now, here, you see, it takes all the running you can do to keep in the same place"
Ecological Research Programs
Tools
• Mathematical models
• Manipulative field experiments
The greater ecological questions:
• Distribution: Where do we find species? And what are the resources they need?
• Abundance: How many individuals can an area support ?
• Procession of life: What should an individual do at what age ?
• Fit of form and function: How do species use the resources in the environment?
Why does this matter at all?
• The gene containment unit.
• Biological beings as computer algorithms
• Survival of the code, not the being.
How does that actually work?
• From the will to change
• To the forced constraints of the environment.
Measuring Biological Success The Jewish Mother Phenomenon
Fitness
1
𝑁
∆𝑁
∆𝑡
Factors impacting fitness
• Energy
• Mate Quality
• Offspring survivorship
• (the all encompassing power)
From Fitness, through Evolution to Ecological Systems• Species in a community compete for resources
• Each resource can sustain multiple species as long the strategies, extraction methods, they use do not overlap.
• Species constantly change their strategies, however balance on the strategy where any change would result in lower fitness, a point called an evolutionary stable strategy (Maynard-Smith and Price, 1973).
Individual 2
Aggressive Submissive
Individual 1 Aggressive (-1, -1) (2,0)
Submissive (0,2) (1,1)
Individual 2
Aggressive Submissive
Individual 1 Aggressive (-1, -1) (2,0)
Submissive (0,2) (1,1)
Some Basic Concepts In Ecology
In the time we have left
Population Dynamics – First and second laws of ecology 1. Every population has the intrinsic potential to grow exponentially.
2. No population can grow exponentially without resource limitations.
Lotka-Volterra Competition Equations
Predator-Prey Limiting Cycles
Diversity
• Species Richness – The Number of species that are found in a system
• Species Diversity – A variable of the number of species in a system with a relative abundance of that species out of the total number of individuals measured.
Whittaker’s Diversities
• α–diversity: Local scale (in a specific plot)
• β-diversity: Between plots (relative)
• ϒ-diversity: Overall diversity in the landscape = α*β
Island Biogeography (McArthur and Wilson, 1967)
SLOSS – Debate (Jared Diamond, 1975)
• Do we make on large nature preserve (ex. The Maasai Mara )
• Or do we have many smaller reserves that protect smaller resource hot spots.
Intermediate Disturbance Hypothesis (Wilkinson 1999)
Holling’s Panarchy (2001)
Let’s test our understanding with actual examples • What research program would the research question fit in?
• How would results of such studies look like?
A couple of examples of ecological research
Effects of land management on ant assemblages
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Spe
cie
s R
ich
ne
ss
Samples
Grazing+Logging
Grazing
Logging
Control
Effects of predation risk by vipers and owls on gerbils and heteromyids • Is the effect of multiple predators cumulative on desert rodents or do
rodents respond to the risk posed only by the greater feared predator?
The Model (optimal patch use theory (Brown 1988))
𝐻 = 𝐶 + 𝑃 +𝑀𝑂𝐶
Divergent Behaviours
0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5 2 2.5 3
GU
D (
g) O
wl
GUD (g) No Owl
Coefficients R2
G. andersoni allenbyi 0.113 0.0197
G. Pyramidum 0.4794 0.258
C. Penicillatus 0.6833 0.619
D. Merriami 1.0262 0.771
How and when did Chameleons reach the Seychelles Islands?