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 Living Things in Ecosystems
 Ecosystems: Everything is connected
 An ecosystem includes ____________________________________________________
___________________________________________________, along with their physical
environment.
 Ecologists often regard an ecosystem as an isolated unit, but ecosystems usually
_________________________________________________________________.
Things move from one ecosystem to another.
 An ecosystem is composed of both ___________________________________________
 Biotic factors are the ________________________________________________
– the animals, plants, and _______________________________________. These
biotic factors interact with each other in complex ways.
 The also interact with the nonliving parts of an ecosystem, the abiotic factors
such as ___________________________________________________________
___________________________________, and nutrients.
 Ecosystems are made up of _________________________________________________
 An organism is ______________________________________________________. A
____________________ is a group of organisms that are able __________________
_____________________________________________________and that share
common genes and therefore resemble each other.
 A population is a group of individuals of the ____________________________________
_________________________________
 A ___________________________ is a group of interacting populations of different
species. ________________________________________________________________
_________________________ make up a community.
 _________________________________________________________________ with its
environment – both the living and nonliving parts – make up its niche. An organism’s
_______________________________________________
 An organism’s niche can include when and how often it reproduces, how many
offspring it has, ____________________________________________________
____________________________, and where it finds shelter.
 Think of an organism’s niche as its lifestyle, or ___________________________
_________________________________________________________________
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 The actual place an organism lives is called ____________________________
 How Species Interact With Each Other
 The living organisms within an ecosystem interact with each other in 5 major ways:
________________________, competition, __________________________, mutualism,
and ____________________________________
 In predation, __________________________________________________ all or part of
another organism.
 The organism that is eaten is called the ______________, and the one that
__________________________________________________________________
 Predators tend to feed on young and weak individuals and _________________
_______________________________________________________. As
populations of prey decline, the predators either switch to other prey or begin to
die off themselves.
 Competition occurs when two or more organisms of the same or different species
_____________________________________________________________________.
Species can even compete even if they ______________________________________
with each other. For example, two organisms could compete for the same food source
even if one is only active during the day and one is only active at night.
 ___________________________ is a relationship in which one organism (___________
__________________) lives in or on another organism (______________________) and
feeds on it without immediately killing it.
 Parasites, unlike predators, usually _____________________________________
____________________ and they generally use the host as a habitat for part of
their lives.
 Most organisms are negatively affected by parasites. Animals and plants may be
_________________________________________, making them more
_____________________________________________________________
 Mutualism is a ___________________________________________________________
______________________________ in which both species receive a benefit.
 Commensalism is perhaps the rarest and strangest type of species interaction.
Commensalism is a relationship in which ______________________________________
________________________________________________________________________

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 Commensalism is hard to identify because just because ____________________
__________________________________________________________________
______________________. Often times we learn that a relationship that we
thought was commensalism is actually mutualism.
 Adapting to the Environment
 Organisms tend to be ______________________________________________________
 In 1859 an English naturalist named ____________________________________
proposed an explanation for this observation.
 Darwin observed that _____________________________________________________
________________________________________________, physiology, and behavior.
 Some of these differences are hereditary – that is, _____________________________
__________________________.
 Darwin proposed that the _________________________________________________
______________________________ over which individuals have offspring.
 Some individuals, because of certain traits, are ________________________________
________________________________ than other individuals.
 Darwin used the ___________________________________________ to describe the
unequal survival and reproduction that results from the _______________________
________________________________________
 He proposed that over many generations natural selection causes the
_________________________________________________________________.
A change in the genetic characteristics of populations from one generation to
the next is known as ____________________________
 According to Darwin’s theory, the process of ____________________________
___________________________________
 Major Points of Theory of Evolution
 1) Overproduction – All organisms have the ability to produce ____________________
_______________________________________________________
 2) Struggle to Survive – The environment _____________________________________
_______________________. The environment is often hostile. ____________________
______________________________. The resources needed to survive and reproduce
are often in short supply. So organisms have to compete with each other for survival.
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 3) Variation – Individuals ________________________________________________
_____________________________________. They may differ in size, coloration,
resistance to disease, and many other traits.
 4) Differential Reproduction – Some inherited traits ____________________________
_________________________ in coping with the environment. Because these
individuals with advantageous traits have more offspring, each new generation will
contain ________________________________________________________________
____________________________________.
 _____________________________________________, the population contains
more and more individuals with the advantageous trait.
 An adaptation is an inherited trait that ________________________________________
___________________________________________________ in a certain environment.
 An organism’s environment includes not only physical aspects, such as climate, _______
__________________________________________, which can be strong forces in
natural selection.
 When two or more species evolve in response to each other, it is __________________
_________________________.
 The _______________________________________________________________ or a
species is called extinction.
 A species is extinct when the last individual member dies. Though extinction is a
natural biological process, ________________________________________ is
causing species to become extinct at an _________________________________
1) What role does the environment play in Darwin’s theory of evolution by natural selection?
2) Many people confuse the terms evolution and natural selection. What is the difference
between the two terms?
3) A population of rabbits evolves thicker fur in response to a colder climate. Is this an example
of coevolution? Explain your answer.
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