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60 Cards in this Set
- Front
- Back
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Two sources of biological patterns
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1. Evolution (nature)
2. Ecology (nuture) |
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Mechanisms of Evolution
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-genetic drift
-gene flow -natural selection -mutation -assortative mating |
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3 different types of speciation
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1. allopatric
2. parapatric 3. sympatric |
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scale in ecology
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-individual
-population -species -community -ecosystem -biome |
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population
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a group of organisms of one species that interbreed and live in the same place at the same time
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Malthusian Catastrophe
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-population exceeds resources
-point at which this happens is known as "the point of crisis" |
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What determines how fast a population grows?
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-birth rates
-deaths -immigrants -emmigrants |
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per capita birth rate
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# of offspring in time interval/# of individuals in total population at beginning of time interval
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per capita death rate
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# of deaths in a time interval/# of individuals in population at start of time interval
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rate (r)
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r is the intrinsic rate of growth
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problems with exponential growth
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-resources become limiting
-decrease of the rate as population grows - death rate increases |
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what happens when death rate increases?
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-intraspecific competition
-natural selection becomes important -density-dependent growth -birth rate eventually matches death rate |
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US population
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-310 million people
-4-5% of total world population -uses more than 20% of total world energy |
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Carrying Capacity of US
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200 million
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equitable society
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-if everyone used the same amount of resources
-(reality) resource distribution is not equitable |
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Human Growth
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- 1 person per square meter dry land in 780 years
- mass of people=mass of earth in 2400 years - human per capita growth rate on earth cannot be maintained at current level - human per capita growth rate will reach 0 |
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How will the growth rate reach 0?
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- increase death rate
- decrease birth rate |
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How to decrease birth rate
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-contraception
-abstinence -sterilization |
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how to increase death rate
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-war
-disease -famine -murder |
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different types of populations
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-spatial
-temporal -morphological -genetic |
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Definition of Ecology (Krebs)
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the study of the interactions that determinethe distribuation and abundance of organisms
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Abundance
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the total number of individuals in a population
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density
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the number of individuals per unit area
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Patterns of dispersion
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- Random
- clumped (most common in nature) - uniform |
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Uniform spacing
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- occurs when there is competition tween individuals
- occurs with territorial organisms |
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clumped spacing
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occurs when individuals clump around a common resource
ex.) river, pond, forest, etc. |
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Stable populations
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-are relatively constant size over time
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unstable populations
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-have outbreaks and extinctions
ex.) gypsy moth outbreak damage |
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population flunctutations can be....
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-cyclical
- erratic -unstable |
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themes of a population
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-spatial
- density and abundance - dispersion patterns - temporal - population stability - morphological/ structural/ age - age/ sex ratio/ age survivorship/ age fecundity |
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demography
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the study of the size and structure of populations and the changes within them
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age structure
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determines rates of population growth and long term tendencies of a population
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survivorship
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measure of the percentage of individuals surviving to a particular age
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why is conservation needed? (human impacts)
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-habitat loss
-introduced species -resource over-exploitation -pollution |
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extinction at population level
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all individuals die in a population
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extinction at species level
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all individuals of a species die
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extinction at clade level
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all individuals of a lineage of life die
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examples of habitat fragmentation
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-roads
-buildings -farmland |
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problems w/ small populations
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-catastrophic event can wipe out entirepopulation
-Inbreeding depression -Accumulation of deleterious mutations -Reductionof genetic diversity |
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Minimum Viable population size
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smallest population that can remain alive
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advantages of MVP
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-Retainfecundity
-Retainevolutionary potential -Retaingenetic diversity -Reducedeleterious alleles |
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Minimum habitiat area
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area required per individual
-larger species need larger area -smaller species need smaller area |
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Sustainable population (ZPG)
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population size for which resources can be produced
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population viability analysis
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estimates probability of population extinction
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communities
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local groups of interacting species at a articular place and time
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different types of community interactions
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-neutral
-amensal -commensal -competition -preditation -mutualism |
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intraspecific competition
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competition within species
-most of the time most fierce type of comp |
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interspecific competion
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competition betweeen species
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asymetery in populations
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some organisms suffer for resources more than others
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direct competition
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2 species directly in physical contact with eachother
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indirect competition
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when species are not directly in contact with eachother
ex.) may be using the same resources |
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exploitation competition
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-indirect
-deals w/ shared resources -asymmetrical competition |
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asymmetrical competition
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larger individuals tend to duffer less than smaller individuals
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interference competition
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-usually direct
-ex.) allelopathy-poison your environment so others can't survive |
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pre-emptive competition
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-arrive first
-earlier order of emergence -get established -maintain a foothold |
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density dependent competition
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severity is a function of density, size, and nutrients
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mutual antagonism
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-higher competition between species than within species
-ex.) murder, eat members of other secies but not members of the same species |
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outcomes of competition
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- competitive exclusion
- coexistence |
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competitive exclusion
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-one species out competes other species and the loser goes extinct
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coexistence
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species 1 and 2 coexist
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