Ecosystems

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• Ecosystems

Chapter 2
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2.1 Everything is Connected

• Scientists dont 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

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What is an Ecosystem?

• 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

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Organism

• 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)

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Population

• 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)

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Community

• Organisms dont 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)

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Niche and Habitat

• Niche is an organisms 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 organisms 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 its
  lifestyle
• Habitat is the actual place on organism lives
  (ex lions habitat is a savanna, cactuss
  habitat is a desert) its address

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2.2 How Species Interact with Each Other

• 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

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Predation

• 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

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Competition

• 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

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Parasitism

• 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

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Mutualism

• 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)

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Commensalism

• 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

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2.3 Adapting to the Environment

• 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

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Evolution by Natural Selection

• 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

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Evolution by Natural Selectioncont

• 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)

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Coevolution

• An organisms 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

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Extinction

• 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