Ecosystems and Living Organisms Lecture 5 Flashcards
What is evolution?
cumulative genetic changes that occur in a population overtime
How does evolution occur?
through natural selection
Who proposed evolution theories
charles darwin, a 19th century naturalist
What is natural selection?
individuals with more favorable genetic traits are more likely to survive and reproduce
What observations is natural selection based on?
- high reproductive capacity
- heritable variation
- limits on population growth or a struggle for existence
- differential reproductive success
What is High Productive Capacity?
produce more offspring than will survive to maturity
What is Heritable Variation?
individuals vary in traits that may impact survival
What are limits on population growth or struggle for existence?
outside pressure on which individuals will survive
What is Differential Reproductive Success?
best-adapted individuals reproduce more successfully than less adapted individuals
What is the Modern Synthesis?
ecologists synthesized Darwin’s theory with growing knowledge of genetics, molecular biology, developmental biology, and the fossil record
What is Archaea?
frequently live in oxygen-deficient environments; often adapted to harsh conditions
What is bacteria?
all other prokaryotes; thousands of species; important in biochemical cycles
What are prokaryotes?
do not possess a cell nucleus or any other membrane-bound organelles
What are eukaryotes?
possess a high degree of internal organization (nuclei, mitochondria, chloroplasts, etc)
What are eukaryotes?
possess a high degree of internal organization (nuclei, mitochondria, chloroplasts, etc)
What is Population Ecology?
study of populations; how and why numbers change over time
What is population ecology important for?
endangered species, invasive species, proper management
What is population density?
the number of individuals of a species per unit area or volume at a given time
What is growth rate?
rate of change of a population’s size, expressed as a percent per year
What is the growth rate formula?
r= b-d
What does “r” stand for in r=b-d?
growth rate
What does “b” stand for in r=b-d?
births/1000 people
What does “d” stand for in r=b-d?
deaths/1000 people
What formula accounts for dispersal?
r= (b-d) + (i-e)
What does “i” stand for in r=(b-d)+(i-e)?
immigration rate
What does “e” stand for in r=(b-d)+(i-e)?
emigration rate
What is dispersal?
movement of individuals in or out of an area
What is intrinsic rate of growth (biotic potential)?
exponential growth under ideal conditions
What are the rates with larger organisms?
larger organisms, smaller rates
What are the rate with smaller organisms?
smaller organisms, faster reproduction rates, larger intrinsic rates of increase
What characteristics determine a species’ growth rate?
- age of onset of reproduction
- fraction of lifespan for reproduction
- # of reproductive periods
- # of offspring per reproductive period
What are environmental limits (resistance to intrinsic growth)?
prevent indefinite reproduction and unfavorable food, water, shelter predation, etc
What is negative feedback mechanism?
change in condition triggers response that reverses condition
What is carrying capacity (K)?
maximum # of individuals an environment can support
What does carry capacity cause?
causes leveling off of exponential growth and s-shaped curve of logistic population growth
What factors affect population size?
density- dependent and density- independent factors
What is a density-dependent factor?
effect on population changes as population density changes (predation, disease, and competition)
What is a density-independent factor?
factors that affects population size, but is not influenced by changes in population density (killing frost, severe blizzard, or fire)
What can density-dependent factors lead to?
to boom-or-bust population cycles
What are biological communities?
communities vary greatly in size and lack precise boundaries
What is an ecological niche?
totality of an organism’s adaptations, its use of resources, and the lifestyle to which it is fitted
What aspects does an ecological niche take into account?
all aspect of an organisms existence
What is a fundamental niche?
potential idealized ecological niche
What is a realized niche?
the actual niche the organism occupies
What are limiting resources?
any environmental resource that restricts the ecological niche of an organism
What is intra-specific?
competition between individuals in a population
What is inter-specific?
competition between individuals in two different species
What is competitive exclusion?
one species excludes another from a portion of the same niche as a result of competition for resources
What is resource partitioning?
coexisting species’ niche differ from each other
What is symbiosis?
an intimate relationship between members of two or more species
What are the three types of symbiosis?
mutualism, commensalism, parasitism
What is mutualism?
symbiotic relationship in which both members benefit
What is commensalism?
symbiotic relationship where one species benefits and the other is neither harmed nor helped
What is parasitism?
symbiotic relationship in which one species is benefited and the other is harmed
What is a keystone species?
a species, often a predator, that exerts profound influence on a community
When do keystone species get noticed?
the dependence of other species on the keystone species is apparent when the keystone species is removed
What is species richness?
the number of species in a community
What is species richness related to?
the abundance of potential ecological niches
What can species richness do to communities?
make them more stable
