BIOL 1604 Lecture Notes - Lecture 2: Photosynthesis, Chemotroph, Natural Disaster

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26 Feb 2017
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Chapter 2: Animal Ecology
Ecology: study of relationships of organisms to their environment and to other organisms.
Abiotic and biotic factors
Hierarchy of ecological systems
Organism: survival and reproduction; the unit of natural selection
Population: population dynamics; the unit of evolution
Community: interactions among populations
Ecosystem: energy flux and cycling of nutrients
Biosphere: global processes
All animals have an optimal temperature at which they like to live, lower limit and upper limit.
Don’t like extremes
Ecological niche
Organisms unique way of life and its relationship to other biotic and abiotic factors
A multidimensional (conditions and resources) concept of the total requirements of a
species
Fundamental niche
An organism free of interference from other species could use the full range of conditions
(biotic and abiotic) and resources in which it could survive and reproduce
Realized niche
Due to pressure from and interactions with other organisms (interspecific competition),
organisms and species are usually forced to occupy a niche that is narrower
Population
Group of individuals of the same species living in a defined geographical area
Populations with higher genetic diversity are generally expected to experience greater
short-term success as well as enhanced opportunities for evolution
o Survival patterns:
Type 1: high survivorship for most individuals until they get old and die
Humans ans other large vertebrates
Type 2: the rate of survivorship is independent of age the environment
affects the young and old alike. Same rate over all ages
Birds and mammals
Type 3: survivorship of young individuals is low
Many fish, most invertebrates and plants
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Cohort: individuals born at the same time
Semelparity: reproduce only once during its life history
Iteroparity: more than one reproductive cycle
Age structure: shows the proportion of individuals in each age group. It is determined by the
rates of birth and death within the population
Population growth and intrinsic regulation
Carrying capacity
Human population growth
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Exponential or J shaped curve. Growth is rapid
due to expanding base of reproductive individuals
Density dependent factors
Influence on individuals in a population varies with the degree of crowding within the
population
Effects increase as population grows: intraspecific competition, predation, parasitism, and
infectious disease
Higher population size = food supply diminishes. Competition increases
Higher density = infections and diseases spread more easily
Higher density = predators are attracted
Higher density = places to live decrease
Density independent factors
Exert their effects on populatiosn more or less regardless of density; mainly abiotic or
catastrophic events
Population regulatuion
Community: a dynamic and interactive group of populations coexisting in a defined geographic
area
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