Ecology Subtitle.

Ecology Subtitle

Introduction Ecology is the study of the interactions of organisms with their physical environment and with each other. Abiotic Factors -non-living temperature Water Sunlight Wind Rocks soil Biotic Factors – living Organic matter Producers Consumers Detritovores disease 1/17/2019 Add a footer

Species, communities and ecosystems
Species = groups of organisms that can potentially interbreed and produce fertile offspring Members of the species may be reproductively isolated in separate populations Population = a group of organisms of the same species living in the same place Community = populations of different species living together and interacting with each other Ecosystem = this is the interaction of a community with its abiotic environment. 1/17/2019 Add a footer

Ways of Feeding 1/17/2019 Add a footer

Food Chain Shows a linear relationship on one organism feeding on another Chemical energy in carbon compounds flows through the food chain All chains end with decomposers

Concept 43.3 Species Are Embedded in Complex Interaction Webs
These webs of interspecific interactions are organized around consumer– resource interactions, especially trophic, or feeding, interactions. Trophic interactions determine the flow of nutrients and energy through communities. Primary producers, or autotrophs, convert energy and inorganic materials into organic compounds that can be used by the rest of the community.

Heterotrophs get energy by breaking apart organic compounds that were assembled by other organisms. Primary consumers (herbivores) eat primary producers. Secondary consumers (carnivores) eat herbivores. Tertiary consumers eat secondary consumers.

These feeding positions are called trophic levels. Omnivores feed from multiple trophic levels. Decomposers feed on waste products or dead bodies of organisms.

Table 43.1

Trophic interactions are shown in diagrams called food webs. Arrows indicate the flow of energy and materials —who eats whom. Food web diagrams show the major interactions in a community, and others can be inferred. For example, competition can be inferred if multiple consumers use the same resource.

Figure 43.6 A Food Web in the Grasslands of Yellowstone National Park
Figure A Food Web in the Grasslands of Yellowstone National Park The arrows point from resource to consumer. Even this highly simplified food web is complex. Primary consumers eat plant material (blue arrows). Secondary and tertiary consumers are carnivores that kill and eat live animals (red arrows). Omnivores such as grizzly bears, coyotes, and ravens eat both plant and animal tissues; ravens and grizzlies also eat carrion (flesh of dead animals that they did not kill; dashed red arrows).

Adding, removing, or changing the abundance of any species has effects that reverberate throughout an interaction web. In Yellowstone National Park, wolves were extirpated by hunting by 1926, which initiated a trophic cascade. Elk were culled each year to prevent them from exceeding carrying capacity, until Elk population then rapidly increased.

The elk browsed aspen trees so heavily that no young aspens could get a start. Elk also browsed streamside willows to the point that beavers (who depend on willows for food) were nearly exterminated. Wolves were reintroduced in 1995 and preyed primarily on elk. Aspen and willows grew again, and the beaver population increased.

Figure 43.7 Removing Wolves Initiated a Trophic Cascade (Part 1)
Figure Removing Wolves Initiated a Trophic Cascade (A) The elk population in Yellowstone National Park increased rapidly after wolves were eliminated and the park stopped removing elk. (B) Aspens did not become established when wolves were absent and abundant elk browsed the trees. (C) Researchers constructed an “elk exclusion” fence to demonstrate that aspen regenerated only inside the fence, where elk were absent.

Figure 43.7 Removing Wolves Initiated a Trophic Cascade (Part 2)
Figure Removing Wolves Initiated a Trophic Cascade (A) The elk population in Yellowstone National Park increased rapidly after wolves were eliminated and the park stopped removing elk. (B) Aspens did not become established when wolves were absent and abundant elk browsed the trees. (C) Researchers constructed an “elk exclusion” fence to demonstrate that aspen regenerated only inside the fence, where elk were absent.

Two practical applications of ecology: Conservation ecology attempts to avoid the loss of elements or functions of an existing web of interactions. The subfield of restoration ecology provides scientific guidance for restoring lost elements or functions of a web.

Reintroducing predators that humans once eliminated is an attempt to restore ancestral ecosystems. It also illustrates a bigger point: if we wish to restore or conserve ecological systems, we must consider the entire web of ecological interactions.

Species introductions also illustrate these points. Species that are introduced into a region where their natural enemies are absent may reproduce rapidly and spread widely. Such invasive species are likely to have negative effects on native species.

Invasive species can harm native species in various ways: Invasive plants can physically crowd out native plants and alter relationships between native plants and their pollinators. Purple loosestrife was introduced to North America in the early 1800s and now dominates wetlands. It competes with native loosestrife, which receives fewer visits from pollinators and produces fewer seeds when purple loosestrife is present.

Some invasive species cause extinction of native species. Example: A sac fungus blight caused extinction of American chestnut trees, which have been replaced by oaks. Chestnut trees produced consistent nut crops each year, but acorn production varies greatly, contributing to yearly fluctuations in rodents, ticks, and Lyme disease in the northeastern United States.

Species introduced to control specific pests can alter the interactions of native species. A weevil was introduced to North America to control invasive musk thistle. When abundance of the thistle declined, the weevil began eating seeds of native thistle species. The weevil has become a competitor of native insects that eat thistles.

Fresh Water vs Marine Ecosystems
1/17/2019 Add a footer

Energy Flow and Primary Production

Energy Book Keeping Less than 1% of all the solar energy that strikes the earth is converted to chemical energy. Accounting for energy Gross Primary Production (GPP) The amount of light energy that is converted to chemical energy by photosynthesis per unit time. Net Primary Production Equal to the GPP minus the energy used by producers for their own cellular respiration energy contained in tissues of primary producers and is available for consumption Examples: Rainforests are among the most productive terrestrial ecosystems and contribute to the bulk of the global net primary production. Coral reefs have a very high GPP but contribute little to the global NPP because they occupy a small portion of the globe Open ocean have a very low NPP but take up a large part of the globe.

Figure 44.6 Energy Flow through Ecological Communities
Figure Energy Flow through Ecological Communities On average, the total amount of energy incorporated into the biomass of a trophic level per unit of time is about one-tenth that of the level it consumes. Of the 90 percent of energy not available to the next trophic level, some is waste or dead material used by decomposers, and some is lost during metabolism as heat.

Diversity in an Ecosystem

Species Diversity is composed of two components
Species Richness The number of different species within a community Relative abundance Population Density and Population size are two ways to measure abundance Population density is a measure of the number of organisms/unit area Communities with greater diversity are better at: withstanding invasive species Recovering from environmental stresses Drought Disease Example: The cavendish banana is the only banana that plantations cultivate.

Concept 44.3 Community Structure Affects Community Function
Ecological efficiency is about 10%. Only about 10% of the energy in biomass at one trophic level is incorporated into the biomass of the next trophic level. This loss of available energy at successive levels limits the number trophic levels in a community.

Concept 44.3 Community Structure Affects Community Function
Ecological efficiency is low because: Not all the biomass at one trophic level is ingested by the next one Some ingested matter is indigestible and is excreted as waste Organisms use much of the energy they assimilate to fuel their own metabolism; this energy is converted to heat and is not available to the next trophic level

Dominant Species The species that is the most abundant or collectively has the highest biomass. Sugar maples in North America forest They effect abiotic factors Provide shade and shelter 1/17/2019 Add a footer

Keystone species 1/17/2019 Add a footer

Bottom-Up and Top-Down Control of a Community
Bottom-up: the lower trophic level influences the success of the higher trophic level. Minerals available to primary producers Top-Down: removing top trophic levels increases the abundance of lower trophic levels .

Biological Magnification
Organism in higher trophic levels can accumulate higher concentrations of toxins in their bodies than those in lower tropic levels Example: The Bald Eagle and DDT (1950) DDT interferes with depositing calcium in eggshells, the thin eggs fell apart and chicks never emerged. Unintended consequences of a helpful idea: DDT and Malaria 250 million of cases of malaria occur each year of which 1 million deaths occur. In Ecuador the use of DDT reduced malaria cases by 61% ( ) 1/17/2019 Add a footer

Saprotrophs 1/17/2019 Add a footer

Community Ecology 1/17/2019 Add a footer

Concept 43.1 Interactions between Species May Increase, Decrease, or Have No Effect on Fitness
Interspecific interactions (between individuals of different species) affect each individual’s life history, and thus survival and reproduction, which in turn determines the individual’s contribution to total population growth rate. The contribution to population growth rate is a measure of the individual’s fitness. The interactions may increase or decrease fitness of either individual. There are five categories of interspecific interactions Competition Predation Herbivory Symbiosis facilitation

Interspecific competition (–/– interactions) Members of two or more species require the same resource. At any one time there is often one limiting resource in the shortest supply relative to demand. Species that share limiting resources are likely to compete.

Competition G.F. Gause developed the competition exclusion principle
Two species cannot coexist in a community if they share a niche, that is, if they use the same resources. If two species share the same niche thus compete for the same resources one of the species will evolve through natural selection to exploit a different resource. Resource partitioning (as observed in the beaks of the Finch on the Galapagos Islands).

Figure 43.1 Types of Interspecific Interactions (Part 1)
Figure Types of Interspecific Interactions (A) Interactions between species can be grouped into categories based on whether their influence on fitness is positive (+), negative (–), or neutral (0). (B) The characteristics of canopy (treetop) and understory (low-growing) vegetation in a forest are largely a product of competition for light. (C) Commensalisms between large grazing ungulates (hoofed animals) and insect-eating birds are found in grassland environments around the world. (D) The interaction between berry-producing plants and berry-eating birds is a mutualism. Here an Eastern bluebird (Sialia sialis) gains nutrition by eating holly berries (Ilex opaca). The holly’s seeds pass through the bird’s gut unharmed, and are deposited in nutrient-rich feces away from the parent plant.

Figure 43.1 Types of Interspecific Interactions (Part 2)
Figure Types of Interspecific Interactions (A) Interactions between species can be grouped into categories based on whether their influence on fitness is positive (+), negative (–), or neutral (0). (B) The characteristics of canopy (treetop) and understory (low-growing) vegetation in a forest are largely a product of competition for light. (C) Commensalisms between large grazing ungulates (hoofed animals) and insect-eating birds are found in grassland environments around the world. (D) The interaction between berry-producing plants and berry-eating birds is a mutualism. Here an Eastern bluebird (Sialia sialis) gains nutrition by eating holly berries (Ilex opaca). The holly’s seeds pass through the bird’s gut unharmed, and are deposited in nutrient-rich feces away from the parent plant.

Consumer–resource interactions (+/– interactions) Organisms get their nutrition by eating other living organisms. The consumer benefits while the consumed organism (the resource) loses. Includes predation, herbivory, and parasitism.

Predation (+/-) Animal to animals or Animal to plant.
Tactics developed for survival Active Defense Hiding, fleeing or defending Passive defense Cryptic coloration or camouflage Aposematic coloration: very bright colors (orange, reds) are warning colors) Batsian mimicry: the copycat. A harmless organism appears to look like a noxious organism. Mullerian mimicry: two or more poisonous species resemble each other thus gaining advantage in their numbers. 1/17/2019 Add a footer

Mullerian Mimicry Batesian Mimicry 1/17/2019 Add a footer

Apply the Concept, Chapter 43, p. 885

Symbiosis Two or more species live in direct contact with each other. Their relationship can be +/+ or +/- or neutral Mutualism Commensalism Parasitism

Symbiosis Mutualism (+/+ interaction)
Mutualisms take many forms, involve many kinds of organisms, and vary in how essential the interaction is to the partners. Examples: Leaf-cutter ants and the fungi they cultivate Plants and pollinating or seed-dispersing animals Humans and their gut bacteria Ant Army Defends Tree

Symbiosis Cont., Commensalism (+/0 interaction): one species benefits while the other is unaffected Brown-headed cowbirds follow grazing cattle and bison, foraging on insects flushed from the vegetation. Cattle convert plants into dung, which dung beetles can use. Dung beetles disperse other dung-living organisms such as mites and nematodes that attach themselves to the bodies of the beetles.

Symbiosis Cont., Parasitism (+/-)
The parasite benefits and the host is harmed Tape worm in the human intestine 1/17/2019 Add a footer

Symbiosis Cont., Amensalism (–/0 interactions): one species is harmed while the other is unaffected Tend to be more accidental than other relationships Example: a herd of elephants that crushes plants and insects while moving through a forest

Relationships between species do not always fit perfectly into these categories. Fish that live with sea anemones escape predation by hiding in the anemone tentacles. Effects of this on the anemones is unclear. Do the fish steal some of their prey? Do they get nutrients from fish feces? It may depend on the availability of nutrients.

Figure 43.2 Interactions between Species Are Not Always Clear-Cut
Figure Interactions between Species Are Not Always Clear-Cut Ecologists long believed that the relationship between sea anemones and anemonefishes was a commensalism: that the fish, by living among the anemones’ stinging tentacles, gained protection from predators. But could it also be considered a mutualism—if the fishes’ feces provide nutrients that are important for the anemones—or competition—if the fish occasionally steal the anemones’ prey?

Population Dynamics

Properties of Population
Size Density Dispersal Patterns Survivorship Curves Age Structure Diagrams Population Growth 1/17/2019 Add a footer

Dispersion Patterns Clumped – most common pattern Uniform Random
Fish, herds (safety in numbers) Uniform Certain plants, territorial birds Random Dandelions Occurs in the absence of special attraction or repulsions. 1/17/2019 Add a footer

Survivorship Curves Type 1 Type 2 Type 3
Organism that have low death rates in young and middle age and high mortality in old age. There is huge investment of energy into parenting Ex. humans Type 2 Species with death rate that is constant over life span Hydra, reptiles, rodents Type 3 High mortality among young BUT death rates decline with age Fish, oysters, invertebrates (thousands of eggs) 1/17/2019 Add a footer

AGE STRUCTURE DIAGRAMS
Scientists use age structure to Predict future growth patterns analyzing factors such as: Number and proportion of individuals in each age group. The number of males versus females in each age group. Compare age groups such as pre-reproductive to reproductive ages shape of the graph to determine: If a population is growing, shrinking or staying the same Growth momentum (how soon overpopulation will become a problem)

Age Structure Diagrams
The shape of the age structure diagram tells you: 1. If a population is increasing, stable or shrinking 2. Population growth momentum- even if people are having less children, the effect won’t take place until much later when the children reach reproductive maturity. 1/17/2019 Add a footer

Age Diagrams Cont., Structure (a) is characteristic of a growing nation- loo at the base. Structure (b) is characteristic of a developed nation with slow growth Structure (C) is characteristic of a declining growth population 1/17/2019 Add a footer

Population Growth Curves
Biotic potential = the maximum rate in which a population can grow under ideal conditions. Factors that effect growth include: Age of reproductive maturity Number of reproductive periods in a lifetime Number of offspring per birth Two types of growth curves occur Exponential or J-Curve Logistic 1/17/2019 Add a footer

Change in the population is dependent on
The number of individuals in a population at some time in the future = the number now + the number that are born – the number that die We turned this word equation into symbols to arrive at Equation 42.1, the most basic mathematical model of population growth: Nt+1 = Nt + B – D OR we can change that to say ΔN / ΔT = B – D where ΔN, the change in population size during some time interval, is divided by ΔT, the change in time represented by that time interval, to yield the rate of change in population size. B-D can be discussed in terms of r, per capita increase ΔN / ΔT = r N When r increases the rate of growth increases; when r decreases growth is reduced 1/17/2019 Add a footer

Logistic Growth has limiting factors
Carrying capacity – limit to the number of individuals that an ecosystem can sustain (K) Populations oscillate around the K-capacity Other factors that change population size Density dependent vs density independent factors K-N tells how many individuals can be added before the population hits carrying capacity (K-N)/K tells us the fraction of the carrying capacity that has not yet been “used up.” r is the rate in which the population is changing 1/17/2019 Add a footer

Exponential Growth Factors that allow for exponential growth
No predators Unlimited resources No immigration or emigration No competition No disease or parasites Populations that see Exponential growth Bacteria Newly founded /introduced to an area Usually short lived before proceeding to logistic growth 1/17/2019 Add a footer

Limiting Factors Density Dependent
Those factors that increase directly as the population density increases. Competition for food Build up of waste Predation Disease Density Independent Those factors whose occurrence is unrelated to population density Earthquakes Storm Naturally occurring fires and flood 1/17/2019 Add a footer

Comparison of Two Life Strategies
Growth Pattern Comparison of Two Life Strategies r- strategist K-strategist 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, fish, oysters Example: mammals r-strategist are opportunistic. They reproduce rapidly when the environment in not crowded and resources are plentiful K-strategist live at a density level close to carrying capacity. 1/17/2019 Add a footer

Chemical Cycles

Water Cycle Water evaporates from the earth, forms into clouds and rains over the oceans and land. Some rain percolates into the soil and makes its way back to the oceans Some evaporate from the lands MOST evaporates from transpiration Oceans = 97% water Glaciers/polar icecaps = 2% Lakes/rivers/ground water = 1%

The Carbon Cycle Cell respiration Burning of fossil fuels
Photosynthesis The major reservoir Fossil fuels Plants Animals Soil Oceans (CaCO32-) CO, CO2 1/17/2019 Add a footer

Carbon Cycles in two main forms
Carbon dioxides, CO2 Methane, CH4 Peat and fossil fuels link to carbon dioxide cycle 1/17/2019 Add a footer

Methane In anaerobic conditions dead organic matters in converted to methane by methanogens. These organisms belonging to the Domain Archaea Methane is emitted from waterlogged habitats (like marshes) and landfills – it is also a gaseous waste produced by ruminants Large quantities of methane are trapped in permafrost Global warming is causing permafrost to melt releasing the methane 1/17/2019 Add a footer

Peat, Coal, Oil and Gas Combustion of Biomass
Carbon compounds in dead organic matter CO2 in Atmosphere Partial decomposition of geological ancient matter, heated, compressed in accumulated in porous roc Partial decomposition in anaerobic/acidic waterlogged conditions Combustion of Biomass Coal, Oil, Gas Peat 1/17/2019 Add a footer

The Nitrogen Cycle Nitrogen Fixing Bacteria
Found in nodule in the roots N2 NH4+ Nitrifying Bacteria NH4+  NO2-  NO3- Denitrifying Bacteria NO3-  N2 Bacteria of decay Decompose organic matter into ammonium (NH4+) 1/17/2019 Add a footer

Human and the Biosphere

Eutrophication Runoff from sewage, manure, fertilizers into the water system leads to high levels of nutrients (Nitrates and Phosphates) for algae to grow in excess. Shallow areas become chokes with weeds. As photosynthetic organism die organic matter begins to accumulate on the bottom of the lake. detrivores use of oxygen levels as they decompose creating hypoxic zones causing fish to perish. 1/17/2019 Add a footer

Acid Rain Acid rain is caused by pollution from combustion of fossil fuels Nitrogen and sulfur release from burning coal Nitric , Nitrous, Sulfuric and Sulfuous acids alter pH in rain to 5.6 1/17/2019 Add a footer

Toxins Chicken and Cattle Carcinogens
Antibiotics and hormones are used to increase the size of live stock for market May cause negative effects on humans Carcinogens Accumulate and remain in fat tissue Toxins from industry entered the food chain DDT and the bald eagle Biomagnification 1/17/2019 Add a footer

Global Warming – Greenhouse Effect
Greenhouse effect is a natural phenomenon which helps us to sustain a warm atmosphere for life to exist. The greenhouse gases which have the largest warming effect within the atmosphere are: water vapour (clouds) and carbon dioxide Other greenhouse gases include: Methane and nitrogen oxides Impact of gases depends on the ability to absorb long wave radiation and its concentration in the atmosphere CO2 levels have been rising due to burning of fossil fuels Aircrafts produce water vapor which has an effect equal to CO2 emissions Other greenhouse gases include methane and nitrogen oxides – these have less impact on the overall warming effect 1/17/2019 Add a footer

Human Enhanced Greenhouse Effect
The excess gases in the atmosphere reflect the heat back into the earth increasing the temperature. This change can influence climate patterns Melting of ice-caps/glaciers Increase rise in sea levels Melting permafrost leads to release of methane Eutrophication Ocean acidification 1/17/2019 Add a footer

Depletion of the ozone layer
Chlorofluorocarbons accumulation used from refrigerated/air-cooling systems and aerosols, have caused the formation of a hole in the ozone ayer Allows more UV light to reach the earth Increase in skin cancer. 1/17/2019 Add a footer

Ocean Acidification Many organisms are able to withstand ocean acidification, but may lose this ability if also exposed to other stressors such as warming, excess nutrients, loss of oxygen, reduced salinity or pollution. Even small alterations at the base of the food web can have knockon effects for higher trophic levels 1/17/2019 Add a footer

Climate change is a better term than Global warming – WHY?

Ocean Acidification and Coral Reefs
30% atmosphere is absorbed by oceans Calcification is predicted to reduce by 30% over the next century (Kleypas et al ) 10% of coral reef fishes rely specifically on corals; however, studies have shown that the abundance of 75% of species of coral reef fishes declined following decreases in coral abundance and that 50% of these fish species showed a decline >50% (Wilson et al. 2006). Chemical dynamics of atmospheric carbon dioxide combining with ocean water. Image courtesy of Phil Munday of James Cook University. 1/17/2019 Add a footer

There are many proposed environmental consequences associated with an enhanced greenhouse effect, including: Disease spread – More temperate climates will increase the prevalence and spread of pathogenic vectors (e.g. mosquitos) Ice caps melting – Higher temperatures are melting ice caps and reducing permafrosts, releasing detritus trapped in ice Extreme weather conditions – Climate change is linked to an increase in extreme weather (e.g. cyclones, tropical storms) Extinction – Changing climate will increase competition, leading to a loss of biodiversity and extinction events Acidification of oceans – Rising atmospheric CO2 levels contribute to an increase in the acidification of oceans Rising sea levels – Global warming is associated with rising sea levels, leading to the displacement of communities Temperature increases – Greenhouse gas emissions are linked to an increase in average global temperatures Habitat destruction – Changing climate conditions will lead to the destruction of habitats and expansion of temperate species 1/17/2019 Add a footer

Pesticides vs. Biological Control
What is the cost to benefit relationship between pesticide use and humans Pest carry disease Pesticides can cause cancer in humans and deplete the ecosystem of valued species Reliant and consistent spraying of pesticides can lead to evolution of the pest (resistance) Biological Control = alternative method of controlling pests. Crop rotation Introduce natural enemies of the pests (with caution) Use natural plant toxins instead of synthetic Insect birth control – males can be sterilized by exposing them to radiation and then releasing them into the environment. 1/17/2019 Add a footer

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