Class Notes (835,006)
United States (324,008)
NSCI 1413 (15)
Lecture 2

NSCI 1413 Lecture 2: Ecology

7 Pages
47 Views
Unlock Document

Department
Natural Science
Course
NSCI 1413
Professor
Guy Robinson
Semester
Fall

Description
Important Vocabulary ● Population:​ A group of individuals of one species living in one area who have the ability of interbreeding and interacting w/ each other ● Community:​ Consists of all the organisms living in one area ● Ecosystem:​ Includes all the organisms in a given area as well as the abiotic factors w/ which they interact ● Abiotic factors:​ Nonliving things that include temperature, water, sunlight, wind, rocks, and soil ● Biosphere:​ The global ecosystem Properties of Populations ● Size:​ The total number of individuals in a population; represented by N ● Density:​ The number of individuals per unit area or volume ○ Mark and Recapture:​ A sampling technique where organisms are captured, tagged, and then released; later, the same process is repeated and the following formula is used for the collected data N = ​(# of marked in first catch)(total # in second catch) # of recaptures in second catch ● 50 zebra mussels are captured, tagged, and released; one week later, 100 zebra mussels are captured and 10 have markings already; using the formula, the total population would be ~500 zebra mussels ● Dispersion:​ The spacing patterns of individuals w/i the area the population inhabits ○ Clumped:​ Mechanism used for survival under the pretence of “safety in numbers” ● Fish traveling in schools ○ Uniform:​ Evenly spread out, usually to prevent one individual from “hogging” resources ● Certain plants secrete toxins that keep away plants who would compete for limited resources ○ Random:​ Occurs in the absence of any special attractions or repulsions ● Tree placement in forests is random ● Survivorship/Mortality Curves:​ Show the size and composition of a population ○ Type 1:​ Shows organisms in low death rates in you and middle age and high mortality in old age; great deal of parenting accounts for the high survival rate of young (ex: humans) ○ Type 2:​ A species w/ a death rate that is constant over the life span (ex: hydra, reptiles, rodents) ○ Type 3:​ Shows a very high death rate among young but mortality rates decline for individuals who have survived past a certain age; characteristic of no parenting (ex: fish) ● Age Structure Diagrams:​ Shows the relative numbers of individuals at each age Population Growth ● Biotic Potential:​ The maximum rate at which a population could increase under ideal conditions; contributing factors include: ○ Age reproduction begins ○ Life span during which organisms are capable of reproducing ○ The number of reproductive periods in a life time ○ The number of offspring the organsism is capable of reproducing ● Carrying Capacity:​ The limit to the number of individuals that can occupy one area at a particular time ● Limiting Factors:​ Factors that limit population growth ○ Density-dependent:​ Factors that ↑ directly as the population density ↑; includes competition for food, buildup of wastes, predation, and disease ○ Density-independent:​ Factors whose occurrence is unrelated to population density; includes natural disasters ● Growth Patterns ○ Opportunistic:​ Species reproduce rapidly when the environment is uncrowded and resources are vast; aka r-strategists ○ K-strategists:​ Live at density near carrying capacity (K) Comparison of Two Life Strategies r-strategists K-strategists Many young Few young Little or no parenting Intensive parenting Rapid maturation Slow maturation Small young Large young Reproduce once Reproduce many times Example: Insects Example: Mammals ● Case Study of The Hare and The Lynx ● Hares eat grass, lynx eat hares; studied population fluctuation using pelt data from hunters ● Lynx population dependent on the hare population as a food source, and change accordingly Community Structure and Population Interactions ● Competition ● Competitive Exclusion Principle:​ Developed by G. F. Gause; cultured two similar species separately, and grew rapidly then leveled out at carrying capacity, but when cultured together, one had the advantage and drove the other to extinction; two species cannot coexist in a community if they share a niche and use the same resources; two outcomes: ● Resource Partitioning:​ One species evolves through natural selection to exploit different resources ● Extinction​ of one species ● Predation:​ Refers to one animal eating another or animals eating plants; defenses have been developed: ● Plants:​ Evolved spines, thorns, and chemical poisons (strychnine, mescaline, morphine, nicotine) to fend off animal attacks ● Animals:​ Evolved active defenses (hiding, fleeing, defending) that be costly in terms of energy; also evolved passive defenses such as: ● Aposematic coloration:​ Very bright coloring indicating poisonous animals as a warning that predators should avoid them ● Batesian mimicry:​ “Copycat coloration”; one harmless animal mimics the coloration of one that is poisonous ● Viceroy butterfly:​ Mimics the monarch butterfly that stores milkweed poison in its body ● Müllerian mimicry:​ Two or more poisonous species resemble each other and gain an advantage in their combined numbers; predators learn quickly to avoid any prey w/ that appearance ● Wasps and Bees ● Mutualism:​ A symbiotic relationship where both organisms benefit (+/+) ● Bacteria in the human intestine that produce vitamins ● Commensalism:​ A symbiotic relationship where one organism benefits while the other is unaware of the other organism or the other is not harmed by the one organism, (+/o) ● Barnacles attach to the underside of whale, gaining access to a variety of food source; doesn’t help or harm the whale ● Parasitism:​ A symbiotic relationship where one organism, the parasite, benefits while the host Is harmed (+/-) ● Tapeworm inside a human Energy Flow and Primary Production ● The sun provides all the sunlight energy to the supply the needs of all living organisms, despite the fact that only less than 1% is actually converted into useable energy via photosynthesis, while the rest is reflected, absorbed as heat, or radiated ● Gross Primary Productivity:​ The amount of light energy that is converted to chemical energy by photosynthesis per unit of time ● Net Primary Productivity:​ Number equal to the GPP minus the energy used by producers for their own cellular respiration ● Tropical rain forests are among the most productive terrestrial ecosystems, providing a large portion of Earth’s overall NPP ● Coral reefs have a very high NPP, but since they occupy a small fraction of the planet, they provide very little to the global NPP Energy Flow and the Food Chain ● Food Chain:​ Pathway along which food is transferred from one trophic level to another ● Biomass:​ Organic material from living, or recently living organisms that serve as fuel ● Only ~10% of the energy stored in any trophic level is converted to organic matter at the next trophic level​ (why trophic levels are so short, only containing a handful of organisms at most) ● Start w/ 1,000g of plant matter, the food chain can only support 100g of herbivores, 10g of secondary consumers, and 1g of tertiary consumers (reduced by factors of 10) ● Population fluctuations at lover trophic levels are magnified at higher levels​ (why short food chains are more stable—endangerment or extinction of lower organisms can lead to the same in higher level consumers) ● Food chains are not isolated​; they are interwoven w/ other food chains into a ​food web​, meaning one organism can occupy a high trophic level in one food chain and a low trophic level in another ○ Producer:​ Convert light energy to chemical bond energy; greatest biomass of any trophic level; autotrophs; bottom of the food chain; most stable trophic level; population fluctuations have no significant effect ● Grass ○ Primary Consumer:​ Heterotrophs; herbivores (eat producers) ● Grasshopper ○ Secondary Consumer:​ Heterotrophs; carnivores (eat primary consumers) ● Mouse ○ Tertiary Consumer:​ Heterotrophs; carnivores (eat secondary consumers); top of the food chain; have the least biomass; least stable trophic level; very sensitive to population fluctuation ● Hawk ● Biological Magnification:​ A phenomenon where organisms at higher trophic levels have greater concentrations of accumulated toxins stored in their bodies than those at lower trophic levels ● Bald Eagle:​ Nearly became extinct in the 1950s due to the pesticide DDT that entered the food chain at the primary consumer level, accumulating at the top in eagles (DDT interferes w/ deposition of calcium in eggshells, so eagle eggs broke easily and few eaglets hatched) ● Decomposers:​ Bacteria and fungi; recycle nutrients back to the soil; critical to the food chain (or else it would collapse) Ecological Succession ● Rebuilding of an ecosystem; the order in which mature ecosystems come to be after major disasters or new colonization of species ● Primary ecological succession:​ When rebuilding begins in a lifeless area where even soil has been removed; characterized by soil building; drived by weathering and organic matter accumulation; very slow and gradual ○ Pioneer organisms:​ The first organism to inhabit a barren area (ex: mosses and lichens); introduced with wind as a vector in spore form ● Once soil is present, pioneer organisms are overrun by larger ​organisms (grasses, bushes, then trees) ● Climax community:​ The final, stable community left as a result of complete ecological succession ● Secondary ecological succession:​ When an existing community has been cleared by some disturbance that leaves soil intact (ex: fires in Yellow Stone Nation Park, 1988) Biomes ● A major biotic community characterized by the dominant forms of plant life and the prevailing climate ● Trend in northerly climates:​ tropical rainforest → desert → grass land → deciduous forest → taiga → tundra ● Trend in mountain ranges (as elevation ↑, and humidity/temp ↓):​ temperate deciduous forest → taiga → tundra ● Marine: ○ Largest biome, covering ¾ of the earth’s surface ○ The most stable biome w/ temperatures that vary little b/c water has a high heat capacity and since volume of water is enormous ○ Provides most of the earth’s food and oxygen ○ Divided into regions classified by the amount of sunlight they receive, distance from the shore, water depth, and whether it is open water or ocean
More Less

Related notes for NSCI 1413

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit