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Chapters 5
Biodiversity is the variety of life on
Earth and the essential
interdependence of all living things
• Scientists have identified more than 1.4 million species. Tens of
millions -- remain unknown
•The tremendous variety of life on Earth is made possible by
complex interactions among all living things including microorganisms.
 What does biodiversity provide for humans?
Vital economic natural resources
Forests (plants, wildlife)
Fresh water (lakes, rivers)
Wildlife and fisheries
• Food Security and new food sources
– Grains, fruits, vegetables, meat, fish
•Jellyfish & sea anemones
•Marine slugs
 Where is the biodiversity
 Everywhere
 Every continent and habitat has unique
life forms
 Concentrated in the tropics
 Panama: > 500 species of breeding
 Arctic: 50-100 species
 Dense concentrations
 There are 3 components of
 Ecosystem diversity- the variety of
ecosystems within a given region.
 Species diversity- the variety of species
in a given ecosystem.
 Genetic diversity- the variety of genes
within a given species.
Diversity of genes
Chihuahuas, beagles, and rottweilers are all the same
species —but they're not the same because there is
variety in their genes.
There are 3 components of
2. Diversity of number of species
For example, monkeys, dragonflies, and
meadow beauties are all different species.
Saki Monkey
Golden Skimmer
Meadow Beauty
There are 3 components of
3. Variety of ecosystems
Lakes, Ponds, and Rivers are all Freshwater Ecosystems.
Rocky coast, Sand Dune, Estuary, Salt Marsh , Coral Reef
are all Marine Ecosystems.
 Species are a group of organisms that is distinct from other groups in terms of size,
shape, behaviour or biochemical properties and that can interbreed to produce
fertile viable offspring.
 Organisms are individual life forms.
 Populations are groups of the same species living in the same place at the same
 Communities are populations of different species that live in the same place at the
same time and interact with each other.
 Measuring biodiversity is difficult.
 Species diversity is the combination of richness and evenness in an area.
 Species richness- The number of species in a given area.
 Species evenness—is the relative distribution of individuals among the species
present in a community.
 Biodiversity is lower in a community that has been disturbed by humans.
 Evolution- a change in the genetic
composition of a population over time.
 Microevolution- evolution below the
species level.
 Macroevolution- Evolution which gives
rise to new species or new genera,
family, class or phyla.
 Change over time is the mechanism of Earth’s biodiversity.
 Understanding it can help scientists perceive how organisms will adapt to their
environment and change over time is crucial with environmental health.
 Genes are physical locations on chromosomes within each cell of an organism and
the complete set of genes in an individual is called its genotype.
 Genotype is the blueprint for all the genes one posses.
 And phenotype is the actual traits expressed in that individual.
 Mutation is the occasional mistake in the copying process that produces a random
change. These mutations get passed on. Most mutations are detrimental but
occasionally they change everything.
 Recombination is another way in which genetic diversity is created when
chromosomes are duplicated during reproductive cell division and a piece of one
breaks off and attaches to another chromosome. This just creates novel traits.
 Artificial selection is when humans determine
which individuals will breed to get a desired set
of traits like in dogs.
 Natural selection is when the environment
determines which individuals will survive and
reproduce. Charles Darwin’s idea of natural
selection can be summed up by; individuals
produce an excess of offspring, not all offspring
can survive, individuals differ in traits, traits are
passed on, and differences in traits are
associated with differences in the ability to
survive and reproduce.
 Fitness is the ability to survive and reproduce
and traits that improve and individuals fitness are
called adaptations.
 Individuals produce an excess of offspring.
 Not all offspring can survive.
 Individuals differ in their traits.
 Differences in traits can be passed on from
parents to offspring.
 Differences in traits are associated with
differences in the ability to survive and
 What do you think are traits that species have that might enable them to survive
 Mutation- occur randomly and can add to the genetic variation of a
population. (Most mutations are bad.)
 Genetic drift- change in the genetic composition of a population over time as a result
of random mating.
 Founder effect- a change in a population descended from a small number of
colonizing individuals.
 Mutation
 Genetic Drift
 Allopatric speciation- when new species are created by geographic or
reproductive isolation.
 Sympatric speciation- the evolution of one
species into two species in the absence of
geographic isolation, usually through the
process of polyploidy, an increase in the
number of sets of chromosomes. When
species form populations that become
reproductively isolation within the same
geographic location. (Mating during
different seasons)
 Natural selection takes a long time. It typically follows a bell shaped curve which
means that an average of individuals will have one form and a few will have other
 There are many ways that natural selection can affect the population.
 Directional selection- an environmental change that occurs gives an advantage to a variation on
one end of the distribution and against the other.
 Stabilizing selection- selection for the average form and against the extremes.
 Disruptive selection- selection for the extremes and against the average.
 Genetic engineering- scientists can now copy genes from a species with a
desirable trait such as rapid growth and insert these genes into another species
now known as genetically modified organisms which can then pass those traits onto
their offspring.
 Range of tolerance- all
species have an optimal
environment in which it
performs well. The limit
to the abiotic conditions
they can tolerate is
known as the range of
 Fundamental niche- the
ideal conditions for a
 Niche – the role of an organism in its habitat, or
how it makes its living
 type of food I eat
 Who else eats you
 Whether you need to survive
 Realized niche- the range of abiotic and biotic
conditions under which a species lives. This
determines the species distribution, or areas of
the world where it lives.
 Niche generalist- species that live under a wide
range of conditions.
 Niche specialist- species that live only in specific
 Fossils- remains of organisms that have been preserved in
rock. Much of what we know about evolution comes
from the fossil record.
 Edge biological communities can interact
when they come into contact at
boundaries called edges.
 Ecotone- transitional zones at edges
 Abrupt edge- abrupt changes between
communities with no edge community
 Mixed edges- species from both
communities invade the ecotone and
compete for resources