Definition of Ecology 1866 Ernst Haeckel: the comprehensive

science of the relationship of the organism to the environment

1927 Charles Elton: Scientific natural history 1963 E. P. Odum: The study of the structure

and function of nature 1972 C. J. Krebs: The scientific study of the

interactions that determine the distribution and abundance of organisms

Ecological spectrum

Biosphere, Landscape, Ecosystem, Community, Population, Organism, Organ system, Organ, Tissue, Cell, Subcellular organelles, Molecules

Branches of EcologyChemical, Molecular, Physiological, Behavioral, Population, Community, Ecosystem, Landscape, Evolutionary, Theoretical, Conservation and management, Biodiversity

Journals: Behavioral Ecology, Biological Conservation, Chemical Ecology, Conservation Biology, Conservation Ecology, Ecological Application, Ecological Modeling, Ecological Monograph, Ecologist, Ecology, Environmental Management, Evolutionary Ecology, Functional Ecology, Journal of Animal Ecology, Journal of Applied Ecology, Journal of Wildlife Management, Landscape Ecology, Molecular Ecology, Oecologia, Oikos, Trends in Evolution and Ecology, etc.

Methods of studying ecology

To understand, describe, explain, predict and control

Scale

Lab experiment, field experiment, natural trajectory experiment, natural snapshot experiment, mathematical model

Ecology of forest birds

5 warbler sp. of similar ecological requirement

Feeding zones

In the presence or absence of other species

Competition and partitioning

Energy budget of bumblebee How to keep warm in cold environment?

Energy gain for feeding – energy loss from flying, feeding and keeping warm

Lab and field studies

Number and kinds of flower visited, sugar content of flower

Energy loss at different temperature

Brown trout v.s. Native Galaxias

Fish → Mayfly nymph → algae

Activity pattern (lab and field exp.)

Habitat preference (natural exp.)

Community effect (field exp.)

Trophic cascade – effects flowing down from one trophic level to the next and the next

Energy flow

Primary production: trout >> Galax

Secondary production: trout >> Galax

Succession of old fields

Natural trajectory vs. natural snapshot

Correlation vs. mechanism

within field comparison indicated introduced sp.↑and prairie sp.↓ as N↑

Field experiment

sp. composition and N supply

Nutrients in the rain forest canopy

Epiphytes mats ~ ½ to 4x of the nutrient content of the foliage of the canopy trees

Photosynthesis, migratory birds, bats

Fox-rabies (math model)

Assumptions: no recovery or immune, no migration, random contact

Biology: life span 2 yrs., 1 cub/yr, latent phase 28 days, die 5 days after becoming infectious

N = S + L + I

dS/dt = (b-d)S -αSI

dL/dt = αSI - dL - βL

dI/dt = βL - dI - γI

α - contact rate

β - reaction rate

γ - rabies-induced mortality

Merits of model

Summarizing current knowledge

Approximation and simplification

Hypotheses testing

Exploring scenarios and situations

Caution in evaluation and prediction

Factors affecting the abundance and distribution of species

Historical factors evolution and speciation continental drift geological and climatic changes

Abiotic factors

chemical and physical environment

Biotic factors

competition, predation, mutualism, etc.

Dispersal

Behavioral factors

Human factors

Darwinian evolution by natural selection

individual variation

variation is heritable

differential reproductive rate

the interaction between the characteristics of individual and the environment

Fitness

a measure of biological success

# of gene or genome put into the next generation

the proportionate contribution that an individual makes to future generation

The fittest individual

those that leave the greatest # of descendants

those that transport more gene to the next generation

Example Model: an annual, only one gene, asexual

reproduction, reproduce only once in life time.

5 genotypes: A, B, C, D, and E

G, S, F = proportion of energy devoted to growth, survival (against predator), and fecundity

# of seed Genotypes Spring/Summer Fall Survival

10 A 2 large 2 seeds 4

10 B 9 small 1 seeds 9

10 C 2 small 4 seeds 8

10 D 4 medium 5 seeds 20

10 E 5 med-small 4 seeds 20

Total 61

G:F:S in A=6:1:1, B=1:1:6, C=1:6:1, D=1:1:1, E=1:1:2

Genotype frequency before after one generation

A 10/50=0.2 4/61=0.06

B 0.2 9/61=0.15

C 0.2 8/61=0.13

D 0.2 20/61=0.33

E 0.2 20/61=0.33

Fitness = # of gene/genome put into the next generation

Fitness of D&E = 20/10 = 2

Fitness of C = 8/10 = 0.8

Fitness of B = 9/10 = 0.9

Fitness of A = 4/10 = 0.4

Questions

Is the population biologically successful?

Are those genotypes equally successful?

What if increase herbivory?

Within species variation

Perennial Achillea lanulosa, transplant and reciprocal transplant

Natural selection by pollution

Industrial melanism

Natural selection by predation