Ecosystems and Organisms

Ecosystems and Organisms

What Are The Three Most Important Aspects of Organisms in an

Ecosystem?

What Are The Three Most Important Aspects of Organisms in an

Ecosystem?

•Populations•Relationships•Evolution

•Populations•Relationships•Evolution

PopulationsPopulations

• Definition: The simplest grouping of organisms in nature.

• Populations depend on:• Resources • Births• Deaths• Immigration• Emigration

• Definition: The simplest grouping of organisms in nature.

• Populations depend on:• Resources • Births• Deaths• Immigration• Emigration

ResourcesResources• Limited resources such as food, water and

living space will result in a population that levels off - carrying capacity.

• This graph shows the growth of a yeast population in culture. After a period of exponential growth, the size of the population begins to level off and soon reaches a stable value. This type of growth curve is called an S-shaped graph

• Limited resources such as food, water and living space will result in a population that levels off - carrying capacity.

• This graph shows the growth of a yeast population in culture. After a period of exponential growth, the size of the population begins to level off and soon reaches a stable value. This type of growth curve is called an S-shaped graph

• If unlimited resources and growth this will result:

• Exponential graph or J curve

• If unlimited resources and growth this will result:

• Exponential graph or J curve

Resources Cont…Resources Cont…

Factors Affecting Birth Rates

Factors Affecting Birth Rates

• Age of reproduction• Number of females• Number of females at reproductive

age• Amount of offspring produced if

high infant mortality rate• Amount of time spent in raising

and protecting young.

• Age of reproduction• Number of females• Number of females at reproductive

age• Amount of offspring produced if

high infant mortality rate• Amount of time spent in raising

and protecting young.

DeathDeath• There are three types of organisms:• Type 1- high survival rate (low death

rate) in the beginning of a life time then faster death rate at the end

• Type 2 - fairly even mortality rate.• Type 3- High death rate in the

beginning, then levels off at the end.

• There are three types of organisms:• Type 1- high survival rate (low death

rate) in the beginning of a life time then faster death rate at the end

• Type 2 - fairly even mortality rate.• Type 3- High death rate in the

beginning, then levels off at the end.

Immigration and Emigration

Immigration and Emigration

• The population will increase or decrease depending on the amount of organisms entering or leaving the area.

• http://www.toppcensus.org/web/Archives/Multimedia.aspx?Category=MT&Filter=27

• The population will increase or decrease depending on the amount of organisms entering or leaving the area.

• http://www.toppcensus.org/web/Archives/Multimedia.aspx?Category=MT&Filter=27

RelationshipsRelationships

• Predator prey - As the predators go up or down so does the prey

• Predator prey - As the predators go up or down so does the prey

Relationships cont..Relationships cont..• Symbiosis- organisms living in direct

contact with each other.• Mutualism- both benefit• Commensalisms - one benefits and the

other is not harmed• Parasitism - one benefits and the other is

harmed

• Symbiosis- organisms living in direct contact with each other.

• Mutualism- both benefit• Commensalisms - one benefits and the

other is not harmed• Parasitism - one benefits and the other is

harmed

CompetitionCompetition

• Intraspecific competition- competition between organisms of the same species.

• Interspecific competition- competition between organisms of different species.

• http://www.globalchange.umich.edu/globalchange1/current/lectures/competition/competition.html

• Invasive species and competition, may cause competition exclusion.

• Intraspecific competition- competition between organisms of the same species.

• Interspecific competition- competition between organisms of different species.

• http://www.globalchange.umich.edu/globalchange1/current/lectures/competition/competition.html

• Invasive species and competition, may cause competition exclusion.

EvolutionEvolution• Adaptive behavior, physiology, and

anatomy from genetic change can result in increased reproduction and ability to survive.

• Coevolution - when two or more species influence each others evolution.

• http://evolution.berkeley.edu/evosite/evo101/IIIF1Casestudyofcoevo.shtml

• http://www.pbs.org/wgbh/evolution/educators/course/session4/elaborate_d.html

• Adaptive behavior, physiology, and anatomy from genetic change can result in increased reproduction and ability to survive.

• Coevolution - when two or more species influence each others evolution.

• http://evolution.berkeley.edu/evosite/evo101/IIIF1Casestudyofcoevo.shtml

• http://www.pbs.org/wgbh/evolution/educators/course/session4/elaborate_d.html

Human PopulationHuman Population

• The human population continues to grow exponentially, why?

• http://www.pbs.org/wgbh/nova/worldbalance/numbers.html

• http://www.starch.dk/isi/energy/population.htm

• http://www.learner.org/channel/courses/biology/units/humev/images.html

• The human population continues to grow exponentially, why?

• http://www.pbs.org/wgbh/nova/worldbalance/numbers.html

• http://www.starch.dk/isi/energy/population.htm

• http://www.learner.org/channel/courses/biology/units/humev/images.html