Ecological Pyramid
• 10% rule
• Only 10% of energy gets passed on
• 90% is lost as heat
Symbiotic Relationships
• Mutualism
• Both organisms win
• Commensalism
• One organism wins, one organism is not effected
• Parasitism
• One organism wins, one organism loses
Population Ecology
• Survivorship curve
Population Ecology
• Exponential vs. Logistic Growth
• R Strategy and K Strategy
Ecological Succession
• Primary Succession
• Pioneer Organisms
• Climax Community
Secondary Succession
• Develops after another community has been destroyed
Darwin and evolution
• History of evolution:
• Linnaeus said that descent with modification does occur and
organisms adapt to environments; however he suggested
the inheritance of acquired characteristics as a mechanism
for evolutionary change
Darwin and evolution
• Darwin’s theory of Evolution:
• Hypothesis: natural selection results in adaptations to
environment
• Galapagos Islands-> natural selection can cause
diversification, including the origin of new species
Darwin and evolution
• Evidence for evolution
•Fossil records:
• History of life
• Gives us the ability to trace descent
• Biogeography shows that the distribution of organisms on Earth is
explainable by assuming organisms evolved in one location
Population genetics
• Hardy Weinberg Equilibrium
• 5 conditions
• No mutations
• No gene flow
• Random mating
• Large population, no genetic drift
• No selection for or against alleles
• Change in gene pool frequency is likely-> microevolution
Hardy Weinberg Equation
• p2 + 2pq + q2 = 1
• p+q=1
• Example problem:
• There are 100 students in a class. Ninety-six did well in the course whereas four blew it
totally and received a grade of F. Sorry. In the highly unlikely event that these traits are
genetic rather than environmental, if these traits involve dominant and recessive alleles,
and if the four (4%) represent the frequency of the homozygous recessive condition,
please calculate the following:
• The frequency of the recessive allele.
• The frequency of the dominant allele.
• The frequency of heterozygous individuals.
How Populations evolve
• Mutations
• Recombination of alleles
•Gene flow
•Nonrandom mating
•Genetic drift
How populations evolve
• Natural selection:
• Most traits are polygenic
• Diversity in a population results in a bell- shaped curve
•Three types of selection:
1.Directional- curve shifts in one direction
•Ex: when bacteria becomes resistant to antibiotics
2.Stabilizing- peak of the curve increases
3.Disruptive- the curve has two peaks
•Ex: species vary because a wide geographic range causes selections to vary
How populations evolve
• Females are expected to be more selective in mates-> few
eggs
• Competition between males for mates; in reference to a
dominance hierarchy and territoriality
• Both increase fitness and selection
How populations evolve
• Females are expected to be more selective in mates-> few
eggs
• Competition between males for mates; in reference to a
dominance hierarchy and territoriality
• Both increase fitness and selection
How populations evolve
• Maintenance of Diversity:
• Despite natural selection, genetic diversity is maintained
• Mutations and recombination still occur
• Gene flow can introduce new alleles
• Natural selection itself sometimes results in variation
Speciation and Macroevolution
• Separation of the species:
• Members of a species breed only among themselves
• Prezygotic isolating mechanism:
• Habitat, temporal, behavior, mechanical, gamete
• Postzygotic isolating mechanisms:
• Zygote mortality, hybrid sterility, and F2 fitness
Speciation and Macroevolution
• Modes of speciation:
• Allopatric speciation- also called geographic speciation, is speciation
that occurs when the biological populations of the same species
becomes isolated from each other and prevents genetic interchange
• Sympatric speciation- the process through which new species evolve
from a singe ancestral species while inhabiting the same geographic
region
Speciation and macroevolution
• Principles of macroevolution
• Macro: evolution of new species and higher levels of classification
• Not-goal directed: species evolve gradually and is not challenged by
short spurts of change ( punctuated equilibrium )
Origin and history of life
• History of Life:
• Oldest prokaryotic fossils, cyanobacteria, were the first organisms to
add oxygen to the atmosphere
• Factors that influence evolution:
• Continental drift help explain the distribution pattern of today’s land
organisms
• Mass extinctions have played a large role in history of life-> tectonic,
oceanic, and climatic fluctuations
Labs
• https://www.youtube.com/watch?v=CMIdyMDHd78 (9:15)
• https://www.youtube.com/watch?v=YH6Cpo1OqJs (beginning until
5:30)
• http://www.youtube.com/watch?v=GUY_-LK_lOc song