Environmental Chapter 5 Review
Commensalism
benefits one species but has little, if any, beneficial or harmful effect not he other (epiphytes=air plants)
Environmental Resistance
combination of all factors that act to limit the growth of a population largely determines an areas carrying capacity carrying capacity= (K) the maximum population of a given species that a particular habitat can sustain indefinitely (logistic curve= s curve= levels off at carrying capacity) (exponential curve= just goes straight up= j curve) -the growth of a population decreases as its size nears the carrying capacity of its environment Why?=
Some factors can limit population size
different species and their populations thrive under different physical and chemical conditions some need bright sunlight, some need shade, hot environment, cold environment, dry or wet conditions range of tolerance=each population in an ecosystem has a range of tolerance to variations in its physical and chemical environment
Some species feed off other species by living on or inside of them
parasitism (host is harmed in some way but the other is benefited) parasite benefits, host is often harmed but not immediately killed parasites are harmful but can promote biodiversity by helping to keep the populations of their hosts in check
Prey species
pre can avoid predation -camouflage -chemical warfare -warning coloration -mimicry -behavioral strategies
Two main types of ecological succession
primary ecological succession -gradual establishment of communities of different species in lifeless areas where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic ecosystem -bare rock exposed by retreating glacier -newly cooled lava -abandoned highway or parking lot -newly created shallow pool or reservoir secondary ecological succession -series of communities or ecosystems with different species develop in places containing soil or bottom sediment -because some soil or sediment is present, new vegetation can begin to grow within a few weeks -begins in an area where an ecosystem has been disturbed, removed, destroyed, but some soil or bottom sediment remains (abandoned farmland, burned or cut forests, heavily polluted streams, flooded land)
No population can grow indefinitely: J curve and S curves Population growth in nature
regardless of their reproductive strategy, no population of a species can grow indefinitely why?= environment can't handle them because there is not enough resources a rapidly growing population of any species eventually reaches some size limit imposed by one or more limiting factors -availability of light -water -temperature -habitat/space -nutrients- -predators -exposure to infectious diseases there are always limited to population growth in nature
Some species evolve ways to share resources
resource partitioning - take resources and divide them up; competition requires energy so some organisms choose to avoid (competition=costly) species may only use parts of a resource -at different times -in different ways (warblers sharing the different parts of a tree)
resource partitioning
take resources and divide them up; competition requires energy so some organisms choose to avoid (competition=costly)
Specialist species: resource partitioning through natural selection
the different birds evolved through mutations (speciation) to eat different foods through their different beak shapes
Communities and ecosystems change over time: ecological succession
the types and numbers of species in biological communities and ecosystems change in response to changing environmental conditions such as: -fires -volcanic eruptions -climate change -clearing of forests to plant crops
Review: Populations can grow, shrink, or remain stable
what are the four variables that govern changes in population size what is the equation for population change Population: -population change=(births+immigration)-(deaths+emigration) age structure
3 factors affect succession
1) Facilitation- lichens, more suitable for other spp., less for itself 2)inhibitation- hinder the establishment and growth of other species (pine needles= acidic soil) 3) Tolerance- plants in late stage succession succeed because they are not in direct competition with other plants for key resources
Why clumps?
1) resources of species needs vary greatly in availability from place to place, so species tend to cluster where resources are available 2) individuals moving in groups have a better chance of encountering patches or clumps resources such as water and vegetation than they would searching on their own 3)Living in groups provides some protection from predators 4)gives some predator species a better change of getting a meal
Three big ideas
Certain interactions among species affect their use of resources and their population sizes There are always limits to population growth in nature Changes in environmental conditions cause communities and ecosystems to gradually alter their species composition and population sizes (ecological succession)
Ecological succession does not follow a predictable path
traditional view -balance of nature and climax communities current view -ever changing mosaic of patches of vegetation in different stages of succession
humans are not exempt from natures population controls
Ireland -potato crop in 1845 bubonic plague -14th century AIDS -current global epidemic
Reproductive strategies
K-selected species- (elephants, whales, humans) low reproductive rate, are carried in mother, larger when born, high parental care, reach sexual maturity at larger age R-selected species-high reproductive rate, young mature outside of mother, reproductive age young, little to no parental care (which one is more vulnerable to extinction= k) (different species have different reproductive patterns)
Consumer species feed on other species
Predation= a member of one species (predator) feeds directly on all or part of a living organism (the prey) as part of a food web Carnivores= pursuit and ambush, camouflage, chemical warfare creates a predator prey relationship (hunter --> hunted) influences the make up of a community
Mutualism
two species behave in ways that benefit both by providing each other with food, shelter, or some other resource -pollination -nutrition and protection -gut inhabitant mutualism
Exploding white tailed deer in the US
1900-deer habitat destruction and uncontrolled hunting 1920's-1930's-laws to protect the deer current deer population explosion -spread Lyme disease -deer vehicle accidents -eating garden plants and shrubs how can we control the deer population?=
Predation
a member of one species (predator) feeds directly on all or part of a living organism (the prey) as part of a food web
When a population exceeds its carrying capacity it can crash
a population exceeds the areas carrying capacity reproductive time lag may lead to overshoot -subsequent population crash -also called dieback damage may reduce areas carrying capacity
natural ecological restoration
ecological succession is an important ecosystem service that tennis to increase biodiversity of communities and ecosystems by increasing species richness and interactions among species in turn enhances sustainability by promoting population control and by increasing complexity fo food webs, which enhances energy flow and nutrient cycling
Most specs compete with one another for certain resources
five basic types of interactions 1)interspecific competition (competition between different species) 2) predation (hunter v. hunted) 3)parasitism (one benefits while other is harmed) 4)mutualism (both benefit) 5)commensalism (one benefits and other isn't affected)
How do communities and ecosystems respond to changing environmental conditions?
how do communities and ecosystems respond to changing environmental conditions? -the structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called *ecological succession*
California's Southern sea otters
indicator species-if the environment is healthy or not what reproductive strategy makes them so vulnerable? why are populations threatened -rise in population of orcas -sharks predation -parasites that breed in cat intestines -blooms of toxics algae fed by urea from fertilizer runoff (bioaccumulation-what does this mean?) before European settlers in the US, the sea otter ecosystem was complex settlers began hunting otters -disturbed the balance of the ecosystem populations depend on solar energy and nutrient cycling -when these are disrupted biodiversity is threatened
Living systems are sustained through constant change
inertia -ability of a living system to survive moderate disturbances resilience -ability of a living system to be rested though secondary succession after moderate disturbance evidence suggest that some ecosystems have one of these properties but not the other -tropical rain forest-fi cleared or beverly damaged, all nutrients stored in vegetation not soil-high species richness high inertia/persistence -grasslands-low inertia (much less diverse) and most plant matter stored in underground roots-high resiliance
Interactions between predator and prey species
intense natural selection pressures between predator and prey populations -at the population level, predation plays a role in evolution by natural selection -animal predators tend to kill the sick, weak, aged, and least fit Coevolution -interact over a long period of time -changes in the gene pool of one species can cause changes in the gene pool of the other -Bats and moths -echolocation of bats and sensitive hearing of moths (evolutionary arms race)
Physical or Chemical factors determine number of organisms in a population
limiting factors-more important than other factors in regulating population growth (chemical and physical factors) (one thing that prevents the species from growing out of control) limiting factor principle-too much or too little of any physical or chemical factor can limit or prevent the growth of a population, even if all other factors are at or near optimal range of tolerance -land-precipitation, soil nutrients, temperature -aquatic-temperature, sunlight, nutrient availability, acidity, oxygen (DO), salinity
Core Case Study: Southern Sea Otters- A species in recovery
live in giant kelp forests by the early 1900's they had been hunted almost to extinction partial recovery since 1977 why care? -ethics -tourism dollars -keystone species-trophic cascade
What limits the growth of populations
most populations live in clumps -pack of wolves -fish on coral reef -flocks of birds -sea otters (rafts of pods) population= group of interbreeding individuals of the same species Population density=can also limit population growth or size of population why? = not enough resources different species have different reproductive patterns
How do species interact?
most species compete (fighting for limited resources) with one another for certain resources five types of species interactions: 1)competition 2)predation 3)parasitism 4)mutualism 5)commensalism each of these affect resource use and population sizes of the species in an ecosystem
competitive exclusion principle
no two species can occupy the same niche in the same habitat at the same time (one will survive and one will die)