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

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Spe

cie

s R

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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

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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?