I.
Miller Chapter 4 Review Material
Chapter 4: Biodiversity and Evolution
a. 4-1: What is Biodiversity and Why is it Important?
i. Biological Diversity (Biodiversity) – the variety of the earth’s species, or varying life
forms, the genes they contain, the ecosystems in which they live, and the ecosystem
processes such as energy, flow, and nutrient cycling that sustain all life
1. Species – a group of organisms with a set of characteristics that distinguish it
from other groups of organisms, and in sexually reproducing organisms,
individuals must be able to mate and produce fertile offspring in order to be
grouped within a species.
a. Species Diversity – the number and variety of the species present in
any biological community
b. Genetic Diversity – the variety of genes found in a population or in a
species
c. Ecosystem Diversity – the earth’s variety of deserts, grasslands,
forests, mountains, oceans, lakes, rivers, and wetlands
i. Terrestrial (land) Ecosystems/Biomes – large regions such as
forests, deserts, and grasslands with distinct climates and
certain species (especially vegetation) adapted to them
d. Functional Diversity – the variety of processes such as energy flow
and matter cycling that occur within ecosystems as species interact
with one another in food chains and webs.
2. We use biodiversity to provide us with food, wood, fibers, energy from wood
and biofuels, and medicines.
3. Plays critical roles in providing us with the ecosystem services that preserve
the quality of the air and water, maintain the fertility of topsoil, decompose
and recycle wastes, and control populations of species that we call pests
4. Also increase the stability of ecosystems and increase the resistance of
ecosystems to harmful invasive species
b. 4-2 How Does the Earth’s Life Change over Time?
i. Fossils – mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves,
and seeds, or impressions of such items found in rocks
1. The entire body of evidence gathered using these methods, which is called
the fossil records, is uneven and incomplete
ii. Biological Evolution (Evolution) – the process whereby the earth’s life changes over
time through changes in the genes of populations of organisms in succeeding
generations.
1. Theory of Evolution – all species evolved from earlier, ancestral species.
a. AKA – Life comes from life
2. Natural selection is a mechanism for biological evolution, in which
individuals with certain traits are more likely to survive and reproduce
under a particular set of environmental conditions than are those without
the traits
a. Which environmental condition favor some individuals over others
b. Advantage was due to a characteristic or trait possessed by these
individuals but not by others of their kind
c. Biological evolution through natural selection has become an
important scientific theory that generally explains how life has
changed over the past 3.5 billion years and why life is so diverse
today.
3. Populations – not individuals – evolve by becoming genetically different
iii. Mutations – changes in the DNA molecules of a gene in any cell that can be inherited
by offspring
1. Development of genetic development or variety in the genetic makeup of
individuals in a population
2. External agents such as radioactivity and natural and human-made chemicals
(called mutagens)
3. Sometimes a mutation can result in a new genetic trait, called a heritable
trait, which can be passed from one generation to the next
iv. Adaption (Adaptive Trait) – any heritable trait that improves the ability of an
individual organisms to survive and to reproduce at a higher rate than other
individuals in a population are able to do under prevailing environmental
conditions.
v. Genetic Resistance – the ability of one or more organisms in a population to tolerate
a chemical designed to kill it
1. Widely used in relation to antibacterial drugs, or antibiotics
vi. Genes mutate, individuals are selected and populations evolve such that they are
better adapted to survive and reproduce under existing environmental conditions
vii. Two limitations on adaption through natural selection
1. A change in environmental conditions can lead to such an adaptation only for
genetic traits already present in a population’s gene pool or for traits
resulting from mutations, which occur randomly.
2. Even if a beneficial heritable trait is present in a population, the population’s
ability to adapt may be limited by its reproductively capacity. Populations of
genetically diverse species that reproduce quickly
a. Rats (years) vs. Elephants (1,000years)
viii. 3 common misconceptions about biological evolution through natural selection –
“Survival of the fittest” –
1. Fitness is a measure of reproductive success, not strength
2. Organisms develop certain traits because they need them
3. Evolution by natural selection involves some grand plan of nature in which
species become more perfectly adapted.
c. 4-3: How Do Geological Processes and Climate Change Affect Evolution?
i. Super continent called Pangaea
ii. Tectonic plates drift has had two important effects
1. Location of continents and oceanic basins have greatly influenced the earth’s
climate and thus have helped to determine where plants and animals can
live.
2. The movement of continents has allowed species to move, adapt to new
environments, and form new species through natural species
a. Earthquakes – can also affect biological evolution by causing fissures
in the earth’s crust that can separate and isolate populations of
species
b. Volcanic eruptions – destroy habitats and reducing, isolating, or
wiping out populations of species
iii. Earth’s climate has changed drastically
1. Cooled and covered much of the earth with glacial ice
2. Warmed, melted ice, and drastically raised sea level, which in turn increased
the total area covered by the oceans and reduced the earth’s total land areas
3. Long-term climate changes have had a major effect on biological evolution by
determined where different types of plants and animals can survive and
thrive and by changing the locations of different types of ecosystems such as
deserts, grasslands, and forest
iv. Impact – the force affecting natural selection has been catastrophic events such as
collisions between the earth and large asteroids
1. Caused widespread destruction of ecosystems and wiped out large numbers
of species
2. Caused shifts in the locations of ecosystems and created opportunities for
evolution of new species
v. The biodiversity principal has enabled life on the earth to adapt to drastic changes
in environmental conditions
d. 4-4: How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
i. Speciation – when one species splits into two or more different species.
1. Certain circumstances, natural selection, can lead to an entirely new species
2. Most common ways in which speciation occurs, a barrier or distant migration
separates two or more populations of a species and prevents the flow of
genes between them
a. Two phases
i. Geographic Isolation – occurs when different groups of the
same population of a species become physically isolated from
one another for a long period of time
1. Separated by a physical barrier (a mountain range,
stream, road), a volcanic eruption, tectonic plate
movements, or winds or flowing water that carry a few
individuals to a distant area
ii. Reproductive Isolation – mutation and change by natural
selection operate independently in the gene pools of
geographically isolated populations.
1. Artificial Selection - Genetic Engineering (human impact
role)
ii. Extinction – the process in which an entire species ceases to exist
1. Species become extinct over a large region (local extinction)
iii. Change dramatically or rapidly, a population of a species faces three possible
futures: adapt to the new conditions through natural selection, migrate (if possible)
to another area with more favorable conditions, or become extinct
iv. Endemic Species – especially vulnerable to extinction
v. Background Extinction Rate – species have disappeared at a low rate
vi. Mass Extinction – a significant rise in extinction rates above the background level
1. Provides an opportunity for the evolution of new species that can fill
unoccupied ecological roles or newly created ones
a. Each occurrence of mass extinction has been followed by an increase
in species have arisen to occupy new habitats or to exploit newly
available resources
vii. The existence of millions of species today means that speciation, on average, has
kept ahead of extinction. However many scientists argue that higher extinction rates
and other evidence indicate that we are experiencing the beginning of a new mass
extinction
1. Primarily due to human activities
2. Largest cause of the rising rate of species extinctions is the loss,
fragmentation, and degradation of habitats.
e. 4-5: What is Species Diversity and Why is it Important?
i. Species Diversity – the number and variety of species it contains
f.
1. Species Richness – the number of different species in a given area
2. Species Evenness – a measure of the relative abundance, or the comparative
numbers of individuals of each species present
3. The species diversity of communities varies with their geographical location
ii. Is plant productivity higher in species-rich ecosystems?
iii. Does species richness enhance the stability or sustainability of an ecosystem?
1. Two hypotheses have emerged
a. The more diverse and ecosystem is, the more productive it will be
b. Greater species richness and productivity will make an ecosystem
more stable or sustainable
c. Most ecologist now accept as a useful hypothesis the idea that species
richness appears to increase the productivity and stability or
sustainability of an ecosystem
4-6: What Roles do Species Play in Ecosystems?
i. Important principal of ecology is that each species has a specific role to play in the
ecosystem where it is found.
ii. Ecological Niche – a species’ way of life in a community and includes everything that
affects its survival and reproduction
1. Habitat – where the place it lives, niche would be the pattern of living
iii. Generalist Species – have broad niches
1. Live in many different places, eat a variety of food, and often tolerate a wide
range of environmental conditions.
iv. Specialist Species – occupy narrow niches
1. Live in only one type of habitat, use just one or only a few types of food,
tolerate a narrow range of climatic and other environmental conditions
2. Because of their narrow niches, specialists are more prone to extinction
when environmental conditions change
v. Niches can be classified further in terms of specific roles
1. Native – those species that normally live and thrive in a particular ecosystem
2. Nonnative – also referred to as invasive, alien, and exotic species
a. Can spread rapidly if they find a new location with favorable
conditions – often do not face predators and diseases that would keep
them under control – may be able to out compete natives species for
resources
3. Indicator – species that provide early warning of damage to a community or
an ecosystem
a. Decline – can indicate the presence of parasites, disease-causing
microbes or pollution in the local environment, habitat destruction
and fragmentation, effects of climate change
b. Birds are an excellent biological indicator
4. Keystone – species whose roles have a large effect on the types of abundance
of other species in an ecosystem
a. Limited numbers in their ecosystem
b. Serve several critical roles
i. Ex. Pollination of a flowering plant species
ii. Ex. Top predators feed on and help to regulate the populations
of other species
c. The loss of a keystone species can lead to population crashes and
extinctions of other species in a community that depends on them for
certain ecosystem services