Ecology Chapter 14

14.2 Community Interactions  when organisms live together in an ecological community they interact constantly.  Three types of interactions –Competition –Predation –Symbiosis

Competition- competing for resources  occurs due to a limited number of resources  Resource- any necessity of life. water, nutrients, light, food.  Competitive exclusion principle- no two species can occupy the same niche in the same habitat at the same time

Predation  Predation- when an organism captures and feeds on another organism.  Predator- hunter  Prey- hunted

Symbiosis  Symbiosis- any relationship where two species live closely together. (3 types) –Mutualism –Commensalism –Parasitism

Symbiosis  Mutualism- both species benefit from a relationship.  Lichens (fungus and Algae) One example is the lichens, little non-descript patches of stuff you see growing on rocks and tree bark. This is a symbiosis, consisting of a fungus and an alga. The fungus provides a protective home for the algae, and gathers mineral nutrients from rainwater and from dissolving the rock underneath. The alga gathers energy from the sun. There are thousands of species of lichen in the world; actually thousands of species of fungi with just a few species of algae which can form a partnership with almost any of them.

Symbiosis  Commensalism – One member of a symbiotic relationship benefits and the other is neither helped or harmed  Ex. Holes used by bluebirds in a tree were chiseled out by woodpeckers after it has been abandoned

Symbiosis  Parasitism- One creature benefits and one creature is harmed  Ex tapeworm. Feeds in a humans intestines absorbing his/her nutrients.

Relationships: Symbiosis = Living Together a) commensalism b) mutualism c) parasitism

Identify these relationships

Chapter 14.4 – Population Growth Patterns  What is a population?  What is exponential population growth?  What happens to a population when it reaches its carrying capacity?

How many mice are in the following population? Estimate! ReadySET Go!

How many did you count? What is the best way to count them? SAMPLING

Population Sampling  Sometimes, the entire population to be studied is small enough for the researcher to include the entire population in the study. –This type of research is called a census study because data is gathered on every member of the population.  Usually, the population is too large for the researcher to attempt to survey all of its members. –A small, but carefully chosen sample can be used to represent the population. –The sample reflects the characteristics of the population from which it is drawn

Sampling Methods  There are LOTS ways to sample a population including: –Biased sampling, Systematic sampling, Stratified sampling, Judgment sampling, Quota sampling, Snowball sampling, Counting method, Hit-or- miss method, etc…  HOWEVER, the most common methods are: –Random and non-random sampling –Each gives you a “best estimate” of the population size

Population Size  Factors that affect: –Natality –Mortality/Fatality –Immigration –Emigration

Population Growth Curves  Explain what is happening to the populations below:

Population Growth Curves  Explain what is happening to the populations below:

 Rate at which a population could grow if it had unlimited resources  If a population reached its biotic potential it would have exponential growth Biotic Potential = Reproductive Potential

The “J” Curve: Exponential Growth

The “S” Curve: Logistic Growth This graph shows a typical population growth curve. Under ideal conditions a population would have a growth with a slow start, then a very fast rate of increase and finally the growth slows down and stops.

Population Density 

Environmental Limits on populations  Density-dependent –Disease –Food –Parasitism –Predation –Competition  Intraspecific  Interspecific  Density-independent –Temperature –Storms –Floods –Drought –Habitat Disruption

Density Dependent  Here is a dramatic example of how competition among members of one species for a finite resource — in this case, food — caused a sharp drop in population.  The graph shows a population crash; in this case of reindeer on two islands in the Bering Sea. Inter or Intra?

Density Dependent  This graph shows the effect of interspecific competition on the population size of two species of paramecia, Paramecium aurelia and Paramecium caudatum.  When either species was cultured alone — with fresh food added regularly — the population grew exponentially at first and then leveled off.  However, when the two species were cultured together, P. caudatum proved to be the weaker competitor. After a brief phase of exponential growth, its population began to decline and ultimately it became extinct. The population of P. aurelia reached a plateau, but so long as P. caudatum remained, this was below the population density it achieved when grown alone.

Density Independent  This graph shows the decline in the population of one of Darwin's finches on Daphne Major, a tiny (100- acre) member of the Galapagos Islands. The decline (from 1400 to 200 individuals) occurred because of a severe drought that reduced the quantity of seeds on which this species feeds. The drought ended in 1978, but even with ample food once again available the finch population recovered only slowly.

Limiting Factors  Definition?

What factors would limit these communities?

Organism Interactions Limit Populations  Predation  Competition –Both types  Parasitism  Crowding/stress

The Human Population Figure 4.10 pg 104

Demography Vocabulary  Age Structure  Immigration  Emigration  Birth/Death Rate

Age Structure Pyramids  These pyramids compare the age structure of the populations of France and India in The relative number (%) of males and females is shown in 5-year cohorts. Almost 20% of India's population were children — 15 years or less in age — who had yet to begin reproduction. When the members of a large cohort like this begin reproducing, they add greatly to birth rates. In France, in contrast, each cohort is about the size of the next until close to the top when old age begins to take its toll.

Age Structure Pyramids  These population pyramids show the baby-boom generation in 1970 and again in 1985 (green ovals).  Profound changes (e.g. enrollments in schools and colleges) have occurred — and continue to occur — in U.S. society as this bulge passes into ever-older age brackets.

Chapter 14.5 Ecological Succession  Vocabulary to Know: –Succession  Primary  Secondary  Pioneer Species –Climax Community

Community  All the populations that live together in a habitat  Habitat is the type of place where individuals of a species typically live  Type of habitat shapes a community’s structure

What is Succession & what causes it?  Changes to a community  Biotic Factor  Abiotic Factors

2 Types of succession  Primary –From nothing –Even the soil must be “created”  Secondary –From soil –Disaster can strike and make it start over

Primary Succession

Secondary Succession

Pioneer Species  Species that colonize barren habitats  Lichens, small plants with brief life cycles  Improve conditions for other species who then replace them

Climax Community  Stable array of species that persists relatively unchanged over time  Succession does not always move predictably toward a specific climax community; other stable communities may persist

Pioneer stage  Climax Community The trend of Succession