Ecology Study Guide

Ecology Study Guide ecosystem - an ecosystem is the study of organisms, their environment, and how they interact (“interactions of a community of organisms with each other and with the abiotic (non-living) environment) - when one part of an ecosystem changes, everything else in the system is affected - trophic structure: a pattern of feeding relationships consisting of several levels - the sequence of food transfer up trophic levels: food chain - the transfer of foods moves up chemical nutrients and energy through the trophic - food web: a network of interconnecting food chains - levels - autotrophs - producers - support all other trophic levels - heterotrophs - consumers - herbivores are primary consumers (the first trophic level) - anyone that eats them: secondary, tertiary, quaternary - detritivores - decomposers - secrete enzymes that digest molecules in organic materials and convert them into inorganic forms - derive energy from detritus (dead material produced from all trophic levels) - prokaryotes and fungi - only about 10% of the energy stored at each trophic level is available to the next level - humans only receive a 10th of energy available to them when they eat meat instead of plants community ecology - community ecology: study of all organisms that inhabit a particular area - a biome: major types of ecosystems that occupy very broad geographic regions - determined from climate, elevation, temperature, precipitation, sunlight, and wind (depends on abiotic factors) - abiotic (non-living) factors: temperature/climate, water/soil, light, wind, natural disasters, fire, pollution - biotic (living) factors: pathogens, introduced/invasive species, humans (always a factor) - - - - community ecology: the study of all organisms that inhabit a particular area niches - ecological niche: sum of an organism’s use of biotic and abiotic resources in its environment - fundamental niche: niche potentially occupied by the species - realized niche: the portion of fundamental niche that the species actually occupies organism: interspecific interactions: “between species” interactions (can be both positive or negative) - occurs when the niches of two populations overlap - competition: lowers the carrying capacity of competing populations (resources used by one population are not used by the other) - predation - herbivory - symbiosis: parasitism, mutualism, commensalism ecosystem - energy flow: moves through components of an ecosystem - chemical cycling: transfer of materials within the ecosystem - ecosystems differ based on their primary production and contribution to the total production of the biosphere - supplied with energy from the sun and the Earth’s interior - life depends on the recycling of chemicals - biogeochemical cycles (biotic and abiotic cycles) - can be local or global population: a group of individuals of a single species that can occupy the same general area - individuals in a population rely on the same resources, are influenced by the same factors, and are likely to interact and breed with each other - can be described by the number and distribution of individuals - population dynamics: interactions between abiotic and biotic factors, causing variation in population sizes - increase through birth and immigration to an area vs. decrease through death and emigration out of the area - population growth: dN/dT = B-D (N - population size, dT - time interval) - dispersion - clumped: resources are unequally distributed, individuals are grouped in patches - uniform: individuals are interacting and are the most equally spaced they can be in their environment - random: the individuals are placed in a random way - the rate of population increase under ideal conditions is described as exponential (j-shaped curve) - eventually one or more limited factors will affect population growth - maximum growth rate is rmax - exponential growth: dN/dT = rN - logistic growth model: idealized population growth that is slowed by limiting factors as the population size increases (has a carrying capacity) - dN/dT = rN(K-N/K) - r: growth of population - N: population size - K: carrying capacity - life history - age of first reproduction - frequency of reproduction - number of offspring - amount of parental care - r-selected: produce more offspring, grow rapidly in uncertain environments - k-selected: raise fewer young, maintain relatively stable populations primary productivity - primary production - carried out by producers - the amount of solar energy converted to chemical energy - produces biomass (the amount of living organic material in an ecosystem) carbon and nitrogen cycles - carbon is the major ingredient of all organic molecules (found in fossil fuels, the atmosphere, and dissolved in carbon compounds in the ocean) - nitrogen is an ingredient of proteins and nucleic acids - essential to the structure and function of an organism - has two abiotic reservoirs: the atmosphere and the soil - nitrogen fixation: converts N2 to compounds of nitrogen that can be used by plants (carried out by some bacteria) biodiversity - a loss of one species can affect the species richness of an ecosystem - genetic diversity: needed for species and populations to adapt to climate change - species diversity: number of different species that are represented in an ecosystem - ecosystem diversity: variations in ecosystems within a geographical location impact of humans on ecosystems - agriculture - urban development - forestry mining and environmental pollution overexploitation: threatened cars, rate trees, typical models of population growth - population growth: dN/dT = B-D (N - population size, dT - time interval) - dispersion - clumped: resources are unequally distributed, individuals are grouped in patches - uniform: individuals are interacting and are the most equally spaced they can be in their environment - random: the individuals are placed in a random way - the rate of population increase under ideal conditions is described as exponential (j-shaped curve) - eventually one or more limited factors will affect population growth - maximum growth rate is rmax - exponential growth: dN/dT = rN - logistic growth model: idealized population growth that is slowed by limiting factors as the population size increases (has a carrying capacity) - dN/dT = rN(K-N/K) - r: growth of population - N: population size - K: carrying capacity limiting factors in population growth - density-dependent (as population density increases, these become more impactful) - competition - disease - crowding (directly decreases fertility) - density-independent (unrelated to population density) - fire - storms - habitat destruction from humans - seasonal changes in weather