Ch. 4 - Population Ecology Ecosystem all of the living organisms and nonliving components of the environment in an area together with their physical environment How are the following things related? mice, deer, gypsy moths, oak trees, ticks Ecosystems are interconnected with other ecosystems. All ecosystems contain: 1. Energy (usually from the sun) 2. mineral nutrients 3. water 4. oxygen 5. living organisms 1
Ecology = the study of how organisms interact with each other and their environments 1. Organism = individual living thing (ex: a plant, an ant) 2. Species = group of organisms that are closely related and can mate to produce fertile offspring (ex: Homo sapiens) 3. Population = all members of the same species that live in the same place at the same time (members of a population usually mate with other members of the same population) 4. Communities = a group of various species that live in the same place and interact with each other (ex: pond community, forest community) 5. Ecosystems = made up of communities 6. Biomes = a number of ecosystems with a characteristic climate, and dominant plant and animal life 7. Biosphere = includes all parts of the earth that supports life. 2
Biotic factors living and formerly living parts of the ecosystem Abiotic factors nonliving parts of the ecosystem (air, water, rocks, sand, light, temperature) Root word alert! a = without 3
Habitat = the place that an organism occupies in an ecosystem (where it lives) Resource = anything an organism needs Niche = organisms habitat, resource use and role in an ecosystem 4
Population = all the members of a species living in the same place at the same time Population density = number of individuals per unit area or volume (ex: # of students/m 2 ) Population dispersion = relative distribution or arrangement of the population within a given amount of space --> 1) uniform distribution --> 2) clumped distribution --> 3) random distribution 5
Uniform Distribution 6
Clumped distribution 7
Random distribution 8
Demographers look at: 1. Age structure distribution of ages in a specific population over a certain time (they use a population pyramid to show this) This is an example of an age structure diagram: Sex ratio = proportion of males to females (seen on an age structure diagram) 9
2. Survivorship percentage of members of a group that are likely to survive to any given age Type I = humans live to be very old (usually developed countries) Type II = similar death rate at all ages (many bird populations and transitional countries ) Type III = many die young (usually poor, developing countries & amphibians) 10
Migration = seasonal movement of individuals between areas Immigration = moving into region Emigration = moving out of region Change in population = (births + immigration) - (deaths + emigration) Earth gains over 200,000 people per day (or 75,000,000/yr) 11
Exponential growth = growth occurring so rapidly that the total increases by many times; increases by a fixed percentage each year 12
Carrying capacity = maximum population that the ecosystem can support indefinitely; usually need to evaluate populations over a long period of time to determine the true carrying capacity Logistic growth = when a population's initial exponential increase is slowed and finally stopped by limiting factors Limiting Factors = characteristics of the environment that limit population growth 13
Limiting factors can be: 1. Density dependent = a factor whose influence changes with the population density (ex: food, space, water, predators and disease) 2. Density independent = a factor whose influence is not affected by population density (ex: floods, fires, hurricanes) 14
Biotic potential = maximum ability to produce offspring in ideal conditions; is based on gestation length (length of time for embryo to develop) and generation time (time from birth to sexual maturity) Orangutan: only have 3 4 offspring in a lifetime Scorpion Fish: release 50,000 100,000 eggs every year 15
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