Transcript Ch 2 powerpoint - Plain Local Schools

Chapter 2:
Ecosystems
2.1 Everything is Connected
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Scientists don’t yet completely understand how the
environment works because it is so complex and
interconnected
Human actions have unexpected effects on the environment
(ex: Borneo in Southeast Asia; pesticide DDT)
The unfortunate chain of events on Borneo occured because
the living things were connected to each other
What is an Ecosystem?
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An ecosystem includes all the different organisms living in a certain
area, along with their physical evironment (ex: coral reef, wetlands)
Ecologists think of an ecosystem as an isolated unit, but ecosystems
usually do not have clear, cut boundaries; things move from one
ecosystem to another (ex: birds fly from one ecosystem in summer to
another in winter)
Ecosystems contain both biotic factors (living parts: animals, plants)
and abiotic factors (nonliving parts: temperature, sunlight, soil type)
All parts work together in an ecosystem, if one part is destroyed, the
entire ecosystem can be affected
Organism
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An organism is one individual living thin)g (ex: an
ant, an ivy plant, a gorilla)
A species is a group of organisms that are able to
produce fertile offspring and share common genes,
therefore, resemble each other (ex: all humans,
domestic dogs)
Population
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A population is a group of individuals of the same
species living in a particular place (ex: the bullfrog
population of a pond, the lion population of a
savanna)
Community
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Organisms don’t exist in isolation, neither does a
population, every population is a part of a
community
Communities are all the living inhabitants of
interacting populations of different species living in
an ecosystem (ex: a pond community includes the
different plants, fish, insects, amphibians,
microorganisms the live in and around the pond)
Niche and Habitat
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Niche is an organism’s way of life (ex: a lion eats other animals
(gazelle, zebra); the leftovers are consumed by scavengers
(vultures, hyenas, bacteria, insects); the lion itself is also food to
ticks, fleas, mosquitoes
An organism’s relationship with its environment, both the living and
the nonliving
Niche includes when and how often it reproduces, how many
offspring it has, what time of day it is most active, where it finds
food; it’s “lifestyle”
Habitat is the actual place on organism lives (ex: lion’s habitat is a
savanna, cactus’s habitat is a desert); it’s “address”
2.2 How Species Interact with Each Other
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Ecosystems are made up of biotic and abiotic
components
The biotic components – organisms – affect one
another
The five major types of interactions are: predation,
competition, parasitism, mutualism and commensalism
Predation
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In predation, one organism kills and eats another organism
The organism that is eaten is called the prey
The organism doing the eating is called the predator
Examples: lions feeding on zebras; cougars eating deer;
snakes consuming mice; birds eating insects; blue whale
feeding on tiny krill
Predators tend to feed on young and weak individuals; as
prey decline, predators either feed on other organisms or die
Competition
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Competition occurs when two or more organisms of the same
or different species attempt to use the same limited resource
Examples: Lions and hyenas fighting over the same carcass;
two plants fighting for a limited amount of sunlight
Species can fight over the same resource and never see one
another, ex: one insect feeding on a certain plant during the
day and another who feeds on that same plant during the
night; because they use the same food source, the two species
are competitors
Parasitism
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Parasites are organisms that live in or on another organism and
feed on it without immediately killing it; parasitism is the
relationship between the parasite and its host
Examples: ticks, fleas, tapeworms, viruses, blood-sucking leeches,
mistletoe
Organism the parasite takes nourishment from is known as the host
The difference between parasitism and competition is that the
parasite does not immediately kill their host; it lives in or on the
host most of its life; and the parasite weakens its host making it
more vulnerable for predators
Mutualism
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Mutualism is the cooperative partnership between
two species in which both species benefit
Examples: clownfish and the sea anemone;
bacteria in your intestines; acacia tree covered in
ants in Central America (when the ants were
removed, the tree suffered)
Commensalism
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Commensalism is the rarest and strangest type of
species interaction
It is the relationship in which one species benefits
and the other is neither harmed or helped
Example: sharks and remoras
2.3: Adapting to the Environment
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Organisms tend to be well suited for their natural
environment
Ex: Kangaroo rats are suited for areas with very little
water (desert): never need to drink water, eliminate
very little water, active at night
Evolution by Natural Selection
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Scientists want to how the close match between organisms and their
environment came about. Charles Darwin, 1859, proposed an answer.
He observed that members of a population differ from each other in
form, physiology and behavior; some differences are due to heredity
(passed from generation to generation)
Environment influences which individuals have offspring; certain traits
allow some individuals to survive and have offspring
Natural selection describes the unequal survival and reproduction from
the presence or absence of particular traits; over the years,
characteristics change over time
Evolution is a change in the genetic characteristics of a population from
one generation to the next
Evolution by Natural Selection…con’t
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Ex: a herd of deer live in lowland areas with warm
climate; some become separated in the high
mountains where the temperatures are cold most of
the year; many die in the cold; the survivors might
have thicker fur; they go on to reproduce with
offspring having the desirable trait; this is an
adaptation (an inherited trait that increases and
organisms chance of survival and ability to
reproduce)
Coevolution
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An organism’s environment includes both the abiotic
and the biotic aspects
When two or more species evolve in response to
each other, it is called coevolution
Can be found between predator (enables them to
find, subdue and capture prey) and prey (enables
them to avoid, escape and fight off predators); ex:
crabs (predator) and marine snails (prey); plants
and herbivores
Extinction
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The irreversible disappearance of a population or
a species is called extinction
When the last individual of an organism dies, the
species is considered extinct
This is a natural process but humans are causing
species to disappear at an alarming rate