Species, Biodiversity, and
Sustainability
Chapters 4, 5, and 9
Biodiversity
• The variety of earth’s species
• The genetic diversity stored in all living
organisms
• The ecosystems in which organisms live
Species
• A set of individuals that can mate and
produce fertile offspring
• 10-14 million species, 1.9 million identified
• Rain forests house up to 50% of all species
on the planet
• Insects make up the greatest percentage of
known species
• Unidentified species – rain forests and
oceans
Types of Diversity
• Species – all the different organisms
• Genetic – the genetic variety available
• Ecosystem – how biomes differ and thus
the species and genetic diversity differ by
area
E.O. Wilson
• Encyclopedia of Life
• First used the term biodiversity in a
scientific paper
• Theory of island biogeography
– Explains how species diversity on islands is
affected by the size and location of the island
– Large islands tend to have more species of a
certain category (insects, birds, or cacti)
Theory of Island Biogeography
• Species richness is determined by:
– The rate at which new species immigrate to
the island
– The rate at which species go locally extinct (on
the island)
• Two island characteristics are also
involved
– Island size (larger =  species richness)
– Island distance from the mainland (closer to
mainland =  species richness)
Islands
• Islands make good study areas because
they are relatively isolated and the arrival
of new species and the extinction of
species can be easily observed.
• Hotspots
Island Biogeography cont.
• Used to study habitat islands – areas of
natural habitat – such as national parks or
wildlife refuges that are surrounded by
developed or fragmented land
Evolution
• Microevolution
– Occurs below the species level
– Different varieties of apples or potatoes
• Macroevolution
– Occurs when new genera, families, classes, or
phyla arise
– The term speciation is restricted to the
evolution of new species
Evolution – 3 pathways
• Artificial Selection
– Humans decide which traits an organism will
be bred for
• Natural Selection
– The environment determines selects
– Favors individuals with greatest “fitness”
meaning an organisms ability to survive &
reproduce
• Random Processes –
– Not based on the organisms fitness, but other
random, nonadaptive processes
Artificial Selection
Evolution by Natural Selection
• Evolution – the process where organisms
change over time through changes in the
genetic characteristics of population in
response to environmental conditions
• Theory of Evolution – All species are
descended from earlier, ancestral species
– The theories of evolution and natural selection
focus on populations and changes in
populations over time rather than individuals.
Evolution by Natural Selection
continued
• Darwin
– Beagle/Galapagos
– On the Origin of Species (1859)
– Natural Selection
• Alfred Russel Wallace
Genes
• Physical locations on chromosomes within
each cell of an organism
• Determine the range of possible traits
(physical or behavorial characteristics)
• Complete set of genes is called its
genotype
• genotype vs. phenotype
Mutations
• Mutation
– random changes in DNA (mistakes)
• Somatic
– Changes that are expressed in the individual
and are not passed on to their offspring
(cancer cells)
• Germinal
– Changes that can be inherited by offspring;
occurs in cells that give rise to gamete cells
Evolution by Random Processes
other than mutations
• Genetic Drift
– Change in genetic composition over time as a result
of random mating
– Usually more important in small populations
• Bottleneck Effect
– A drastic reduction in the size of a population
causes a corresponding decrease in genetic diversity
• Founder Effect
– When a few individuals migrate to a previously
unpopulated area
Natural Selection
• Trait
– A characteristic possessed by some individuals
that allow them to survive and reproduce at
higher rates that other members of the population
– These traits become more common in the
population over time
• Adaptation or adaptive trait
– Any heritable trait that improves the ability of an
individual organism to survive and to reproduce
at a higher rate than other individuals in a
population under prevailing environmental
conditions
Natural Selection cont.
• In order for natural selection to take place,
adaptive traits must lead to differential
reproduction which enables individuals
with the trait to produce more surviving
offspring than other members of the
population produce.
– Peppered moth (White – Black – White)
– Water “SuperLions”
– English Bulldog – what would happen if we
left them to reproduce on their own
Genetic Resistance
• Crops
• Bacteria
Limits to Natural Selection
through adaptation
• The genetic traits already present in the
population
• Length of time required for reproduction
to occur
– Bacteria vs. insects vs. elephants
Geologic Processes affect
Natural Selection
• Movement of tectonic plates
– Changes in climate
– Populations can disperse to new areas and
adapt to new environmental conditions when
plates come together
– Populations evolve under isolated conditions
or become extinct when plates move apart
• Earthquakes and Volcanoes
• Climate change – Earth has cooled and
warmed many times
Evolution of new species
• Speciation
– One species splits into two or more different
species
– New species are formed when organisms
have evolved to a point where they can no
longer successfully produce fertile offspring
with members of the original species.
– Occurs when a barrier occurs or migration
takes place which prevents the flow of genes
between two or more populations of a species
Isolation
• Geographic
– When different groups of the same population
become physically isolated from one another over
a long period of time.
• Physical barriers such as mountain range, streams,
roads, volcanic eruptions, winds or flowing water
that carry individuals to a distant area
• Reproductive
– Natural selection occurs independently in
geographically isolated populations of the same
species and over time, the two populations are no
longer reproductively compatible. The individuals
may be able to physically mate but are unable to
produce fertile offspring
Speciation
• Allopatric Speciation
– When new species arise as a result of both
geographic and reproductive isolation
• Sympatric Speciation
– When new species arise in the absence of
geographic isolation
– Generally occurs in polyploid species (most
are diploid)
Sympatric Speciation of Wheat
Adaptation of species depends
on four factors
• Rate of environmental change
– Changes in pH of water (overnight or years)
• Genetic variation
– Greater genetic variation makes it easier for
species to adapt
• Population size
– Small populations with a beneficial mutation
will be able to spread the trait more quickly
• Generation time
– Short generation time = adapt more quickly
Genetics of Populations
• Artificial selection
– Most grains, fruits, and vegetables
– Sweet corn, grapple
– AKC dogs
• Genetic Engineering
– GMOs
– Roundup resistant plants
– Tomatoes
Species Diversity and Richness
• Diversity
– The number and variety of species an
ecosystem contains
• Richness
– The number of different species
• Evenness
– The comparative numbers of individuals of
each species present
– Deciduous forests = low species evenness
– Tropical forests = high species evenness
Species Rich Ecosystems
• High species richness appears to increase
the productivity and stability of an
ecosystem
• Are less affected by drought and invasive
insects
• Take up more CO2 and nitrogen – thereby
having a greater impact on nutrient cycles
Hotspots
• Areas with large numbers of species –
frequently in danger of habitat loss
–
–
–
–
Islands
Tropical rain forests
Coral reefs
Bottom of the ocean
Ecosystem Roles
• Niche
– The role of each organism within it’s
ecosystem
– Includes the specifics about the organisms
requirements: food, water, sunlight, space,
prey, predators, temperature range
Generalist vs. Specialist
• Generalist
– Broad niches: live in many different places, eat a
variety of foods, tolerate a wide range of
environmental conditions
– Ex. Cockroach, mice, white-tailed deer, humans
• Specialist
– Narrow niches: specific habitat, one or a few
types of food, sensitive to temperature and other
climate changes
– Advantage is less competition for their specific
resources in stable environmental conditions
– Disadvantage: More prone to extinction
– Ex. Giant Pandas, Lemurs, shorebirds
Roles within Ecosystems
• Native species
– Endemic species
• Non-native (invasive, alien, exotic)
– Many are beneficial – food crops like wheat, rice,
fish (tilapia or catfish – farm raised)
– Harmful: African Honeybees, Kudzu, Zebra
Mussels, pythons (everglades)
– Invasive species can be accidental (zebra mussels
and fire ants) or intentionally introduced (Kudzu,
European wild boars)
– Invasive species often lack predators, parasites or
pathogens which allow their populations to explode
Fig. 9-14, p. 203
Indicator Species
• Indicator
– Species that provide early warning of danger
to a community or ecosystem
– Birds, butterflies, amphibians
– Often vulnerable to habitat loss and
fragmentation, or pesticide usage
Amphibians
• Frogs sensitive to environmental changes
–
–
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–
–
–
–
–
Habitat loss and fragmentation
Prolonged drought
Increases in UV radiation
Parasites
Viral and fungal diseases
Pollution
Climate change
Overhunting
Invasive species
Keystone Species
• Keystone
– Species whose roles have a large effect on the
types and abundance of other species in an
ecosystem
– Small number of organisms with large impact
so they are frequently the top predators in an
ecosystem
– Loss of keystone species can lead to
population crashes and extinctions of other
species
– Alligators, sea otters, sharks, pollinating
insects
American Alligator
• Keystone Species
– Dig gator holes (hold water during dry spells,
serve as refuges for aquatic life)
– Build nesting mounds which later provide nesting
sites for herons, egrets, and turtles
– Eat large numbers of gar – keeping fish
populations in check
– Placed on endangered list 1967 due to overhunting
– 1977 reclassified as threatened
• Ecosystem services:
– Maintain waterways by keeping them free of
vegetation
Foundation Species
• Foundation
– Species that play a major role in shaping their
communities by creating and enhancing
habitats in ways that benefit other species
– Beaver, Elephant
•
•
•
•
•
•
•
•
•
•
•
Keystone or Foundation?
Sea Stars
Elephant
Gopher Tortoise
Beaver
Alligator
Kelp
Corals
Sea Otters
Grizzly Bear
Prairie Dogs
Gray Wolf
Species Interactions
• Competition
– Species interact to gain access to limited resources
• Predation
– Organism feeds directly on another organism
• Parasitism
– Organism feeds on another living organism, by
living on or inside the host
• Mutualism
– Interaction that benefits both species
• Commensalism
– Interaction that benefits one species, but has little
or no effect on the other
Competition
• Specialist vs. Generalist
• Niche overlap
• Resource distribution – if one species is able to take
over the majority of resources other species must
move to another area, adapt by shifting feeding
habits, or the population will decline and eventually
go extinct
3 types of resource partitioning
• Resource partitioning
– Adaptations that allow species to reduce or avoid
competition with other species for resources
– Temporal
• Use of different resources due to time of use
• Diurnal vs. nocturnal
– Spatial
• Specialized feeding areas
– Morphological
• Specialized physical adaptations (beaks, claws, use
of tools etc)
Spatial Resource Partitioning
Morphological Resource Partitioning
4 Types of Predators
• The use of one species as a resource by another species
– True predators
• kill & consume their prey
• lions and owls
– Herbivores
• eat only part of their prey and do not kill it
• gazelles and deer
– Parasites (including pathogens)
• live on or in the organism they consume (the host)
• can live in bloodstream, intestines or other areas
• individual parasites rarely cause the death of the host
• Pathogens – virues, fungi, protists, wormlike organisms called
helminths
– Parasitoids
• lay eggs inside other organisms and then the larvae eat their way out,
frequently causing the death of the host
• Wasps and flies
Predator – Prey Relationship
• Examples:
– Grizzly bear/salmon
– Kelp/sea urchins/sea otters
– Rats on islands – what happens?
• Methods of predation
– Pursuit and ambush
– Camouflage
– Poison
Camouflaged
Predators
Predator – Prey Relationships
• Methods to avoid Predation
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Protective shells or spines
Regenerative parts
Camouflage
Poison/irritants
Warning coloration
Bad smell or taste (bitter)
Mimicry
Behavioral strategies: puffer fish, peacock
One of many: flocks, herds, schools
Camouflaged
Prey
Fig. 5-5, p. 109
Predator – Prey Relationship
• Predation plays a role in evolution by natural
selection
• Animal predators tend to kill the sick, weak,
aged, young, and least fit members of a
population because they are the easiest to
catch.
• This leaves behind individuals with better
defenses against predation.
• These individuals tend to survive longer and
leave more offspring with adaptations that
can help them avoid predation.
Coevolution
• The predator – prey relationship drives
evolution through natural selection
• Most effective predators produce the
greatest number of offspring and most
effective prey also produce the greatest
number of offspring –
• Changes in the genetic makeup of
populations is the result
• Ex. Bats and moths
A Case Study of Coevolution:
Squirrels, Birds, and the Pinecones They Love
Lodgepole Pine
Red Squirrel
Crossbill
Areas where reds squirrels are the major predator of lodgepole pine seeds, cones are
heavy, wider, and contain few seeds. Areas where crossbills are the major predator (no
red squirrels) of lodgepole pine seeds, cones are larger, with heavy thick scales, and
more seeds. Crossbills with deeper, shorter, less curved bills are more able to get seeds
from these cones…will they evolve to be the dominant form of crossbill?
Parasitism
• Parasite is usually much smaller than the
host and rarely kills the host
• Often gradually weaken host over time
• Parasite can live inside (tapeworms,
lungworms) or outside (fleas, ticks, ) the
host
Mutualism
• Two or more species behave in ways that benefit
both by providing food, shelter, or some other
resource
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–
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Flowers - bees, butterflies, hummingbirds
Oxbirds and rhinocerous
Clownfish and anemone
E-coli in your gut
Acacia Trees and ants
Lichens – fungi/algae
Coral reefs – coral and algae
• Each species benefits by unintentionally exploiting
the other as a result of traits they obtained through
natural selection.
Commensalism
• Commensalism
– Interaction that benefits one species, but has little
or no effect on the other
– Examples:
• Epiphytes (orchids and bromeliads) air plants
• Birds nesting in trees, squirrels nest in trees
• Barnacles on whales or scallops
• Remoras – hitch a ride on larger species especially
whales and feed off leftover food scraps
• Fish hiding in coral reefs
Populations
• Population – a group of interbreeding
individuals of the same species
• Generally live together in groups due to
– Availability of resources specific to their
needs
– Better able to locate resources when in groups
– prey species – improved chance of survival
when in large groups
– Better chance of hunting success for predators
Populations Review
• Four variables affect population
– Births, immigration, deaths, emigration
• Age structure determines growth rate
• J-curve and S-curve
• Carrying capacity
r and k selected species
r and k selected species
r and k selected reproductive patterns
• r selected
– Many offspring, usually small, little parental
care
– Overcome massive losses by producing many
offspring
• k selected
– Larger animals, low reproductive rates, high
parental care
– Invest in success of offspring by providing
care
Traits of K and r selected species
Trait
K-selected
r-selected
Life span
Long
Short
Time to reproductive maturity
Long
Short
# of reproductive events
Few
Many
# of offspring
Few
Many
Size of offspring
Large
Small
Parental care
Present
Absent
Population growth rate
Slow
Fast
Population regulation
Density dependent
Density independent
Population dynamics
Stable, near carrying
capacity
Highly variable
Limiting Factors
• Range of tolerance
– The limits of a range that species can tolerate;
Examples:
• Aquatic: salinity, temperature, dissolved oxygen
• Terrestrial: sunlight, precipitation, nutrients (N, P)
• Limiting factor principle:
– too much or too little of any physical or chemical
factor can limit or prevent growth of a population,
even if all other factors are at or near optimal range of
tolerance
• Environmental Resistance
– the combination of all factors that limit the growth of
a population – determines carrying capacity
White-Tail Deer Discussion
• Should we increase the number of deer hunted each
year in order to decrease car-deer collisions?
• Which is more inhumane – hunting or allowing a
population crash (starvation)?
• What should be done about deer eating expensive
plants?
• What do you think about birth control for deer? Male
and female deer?
• Should we reintroduce large predators, wolves and
mountain lions?
• What is the flaw in “hunting as population control”
argument?
• What is the flaw in birth control for deer argument?
Carrying capacity and population crashes
• Population crash
– When a population suffers a sharp decline or
dieback
• Carrying capacity
– is not fixed, it can be affected seasonally or
yearly based on environmental factors such as
prey/predator abundance, precipitation, or
weather conditions
Population Characteristics
• Size
– (N) total number of individuals within a defined area
• Density
– The number of individuals in a population found in a
particular area
• Distribution
– How individuals are distributed w/ respect to one another
• Sex Ratio
– Ratio of males to females (# of females is more import)
• Age Structure
– Predication of population growth
Population Density
• High Population density
– Improve chances of finding a mate, provide
protection from predation, increases competition for
resources, increases threat from disease
• Density dependent controls
– Influence an individual’s probability of survival and
reproduction based on the population density
– Parasitism, infectious disease, resource competition
– Keep the population near the carrying capacity
• Density independent controls
– Impact regardless of population size or density
– Weather, natural disasters, pollution, habitat
destruction
Population Distribution
• Random distribution
– No pattern to the location of the individuals
– Trees in a forest
• Uniform distribution
– Individuals are evenly spaced
– Tree plantations or nesting gannets
• Clumped distribution
– Organisms frequently live in large groups
– Schooling fish, flocking birds, herding
mammals
Patterns of population change
• Stable
– At or near carrying capacity for long time periods
• Irruptive
– Grow to a high peak then crash (algae, insects)
• Cyclic
– Rise and fall in cycles of years or decades
(lemmings, lynx, snowshoe hares)
• Irregular
– No rhyme or reason for variations
Survivorship Curves
• Type I – convex curve
– Most individuals live to adulthood, with
mortality occurring with old age
– K-selected species
– Elephants, whales, humans
Survivorship Curves
• Type II – A straight line
– Relatively constant decline in survivorship throughout
their natural life span. The individuals chance of
dying is independent of age
– Species that are neither strongly K-selected nor
strongly r-selected
– Squirrels, corals, birds
Survivorship Curves
• Type III – concave curve
– Few individuals survive to adulthood, but
then the chance of dying decreasing with age
– r-selected species
– Plants, insects, oysters, rodents, algae
Ecological Succession
• The normally gradual change in species
composition in a given area
• Primary ecological succession
– First establishment of biotic community
• Secondary ecological succession
– Secondary establishment of biotic community
in an ecosystem that has been disturbed by
natural or human forces
Primary ecological succession
• Primary ecological succession
– The gradual establishment of biotic
communities where there is no soil in a
terrestrial ecosystem or no bottom sediment in
an aquatic ecosystem
– Bare rock from retreating glaciers, cooled
lava, abandoned highway or parking lot,
newly created ponds or reservoirs
– Hundreds to thousands of years
– Lichens and mosses are pioneer species
Primary Succession
Secondary ecological succession
• A series of communities or ecosystems with
different species develop in places containing soil or
bottom sediment
• Occurs in areas that have been disturbed, removed,
or destroyed, but some soil or bottom sediment
remains
• Examples: abandoned farmland, burned or cut
forests, polluted waterways, flooded land
• Succession is a continuous event, ecosystems are in
a constant state of change due to the continuous
struggle of species to achieve enough resources
• Climax Community: last stage of succession,
dominated by a few long-lived plant species in
balance w/ other aspects of the environment
Secondary Succession
Aquatic Succession
Persistence vs. resilience
• Persistence:
– the ability of a living system to survive
moderate disturbances
• Resilience
– The ability of a living system to be restored
through secondary succession after a more
severe disturbance
• Tropical rain forests
– High persistence, low resilience
• Grasslands
– Low persistence, high resilience
Extinction
• The process by which an entire species ceases to
exist (biological extinction) or a population of a
species becomes extinct over a large region, but not
globally (local extinction).
• Background extinction rate
– The natural low rate of species extinction over time
• Mass extinction
– The extinction of many species in a relatively short
period of geologic time
– 5 mass extinctions recorded in the fossil record
– Currently undergoing the 6th (2-25% of all species are
expected to become extinct by 2020) this one is
considered to be caused by humans
Extinction Rates
• Extinction rate
– The percentage or number of species that go
extinct within a certain period of time
– Rates are rapidly rising due to human influences
including: habitat destruction, pollution,
– Extinction rate may rise to 1% per year which
would lead to the loss of ¼ of the biodiversity
currently on the planet
– Focusing conservation efforts on hotspots is
considered the best and quickest way to slow
extinction rates
– It will take 5 – 10 million years to replace the lost
diversity
Endangered and Threatened Species
• Endangered
– Has so few remaining individuals that the
species could soon become extinct
– Polar bears, sea otters, California condor,
whooping crane, almost all big cats, red wolf
• Threatened (vulnerable)
– Still has enough remaining individuals to
survive in the short term, but because of
declining numbers, it is likely to become
extinct in the near future
Reasons to prevent extinctions
• Species diversity
– are essential to provide the planets life
support services
• Ecosystem services
– Nutrient cycling, pollination, flood control etc.
• Economic value
– Value as ecotourism and for medicines
• Ethical right of species to exist
HIPPCO
• Causes of endangerment and extinction listed
in order of importance
•
•
•
•
•
•
H – Habitat Destruction, degradation, fragmentation
I – Invasive or non-native species
P – Population growth and increasing use of resources
P – Pollution
C – Climate change
O – overexploitation of resources
• Areas of greatest rate of extinction: tropical forests, coral
reefs, wetlands and grassland destruction, pollution of
bodies of water, and islands (63% of Hawaiian species at
risk)
Habitat Fragmentation
• When a large, intact, area of habitat such as a
forest or natural grassland is divided, typically
by roads, logging operations, crop fields, and
urban development into smaller isolated patches
or “habitat islands”
• Blocks animal migration routes, isolates groups
making them more vulnerable to predators,
resource competition, disease etc.
• Habitat islands include national parks, nature
reserves, and freshwater lakes which are
frequently surrounded by detrimental human
activities
Human contributions to species
endangerment
• Human population growth will lead to
ever increasing threats to species
– Habitat destruction, degradation,
fragmentation
– Pollution
– Wildlife trade (live and body parts)
– Bush meat
– Pesticide use
• Bioaccumulation
• Biomagnification
Treaties and Laws
• Lacey Act
– Passed in 1900
– Protects plants and wildlife
– the Act prohibits trade in wildlife, fish, and
plants that have been illegally taken,
possessed, transported or sold
– There is some disparity in the application of
the act for plants vs. animals
Treaties and laws
• Convention on International Trade in
Endangered Species (CITES)
– Signed by 175 countries bans the hunting,
capturing, and selling of threatened or
endangered species (lists 900 species), restricts
international trade of approximately 5000
species of animals and 28,000 species of plants
– Of limited value due to lack of enforcement,
convictions lead to small fines, member
countries can exempt themselves from any
listed species, and most illegal wildlife trade
occurs in countries that did not sign the treaty
– IUCN maintains a list of threatened species
known as the Red List
Treaties and Laws cont.
• Convention on Biological Diversity (CBD)
• 3 objectives
– Conserve biodiversity
– Sustainably use biodiversity
– Equitably share the benefits that emerge from the commercial
use of genetic resources such as pharmaceutical drugs
• Constitutes a legal commitment by ratifying countries
• Focuses on ecosystems rather than individual species
• Ratified by 191 countries (excludes US, Iraq, Somalia, Andorra)
• Implementation has been slow
• No severe penalties or enforcement mechanisms
• In 2010 the convention evaluated the progress made and the
results were dismal: at-risk species have moved closer to
extinction, habitat fragmentation and loss is ↑, genetic diversity is
↓, ecological footprint of humans is ↑, ecosystem functioning ↓
Treaties and Laws cont.
• Endangered Species Act of 1973 (ESA)
– Was designed to identify and protect endangered
species in the United States and abroad
– The most far-reaching environmental law ever
adopted by any nation
– NMFS and USFWS were tasked with identifying
and listing all threatened and endangered species
without consideration of economic or political
factors
– Develop recovery plans and can consider
economic factors in deciding what and how to
protect species
ESA continued
• Makes it illegal for Americans to sell or
buy any product made from an
endangered or threatened species, or to
hunt, kill, collect , or injure any such
species in the United States.
• Originally listed 92 species,
• 1,370 species were listed in 2010
• Endangered and Threatened Species
• Endangered species map
ESA continued
• Controversy
• Affects private landowners
• Economic costs ($ 0.09/citizen/year)
• Significant successes
– 50%+ of listed species are stable or improving
– 99% of protected species are still surviving
– Alligator, gray wolf, peregrine falcon, bald
eagle, brown pelican
Preserving Genetic Diversity
•
•
•
•
Gene or seed banks
Captive breeding
Egg pulling
Artificial insemination, embryo transfer,
incubators and cross fostering
• Captive population of endangered species should
number 100 – 500 in order to avoid extinction due
to disease
• 10,000 individuals are required for a species to
maintain its capacity for biological evolution
• Genetic diversity includes crops and livestock as
well as wild plants and animals
Precautionary Principle
• When substantial preliminary evidence
suggests harm to human health or the
environment, we should take
precautionary measures to prevent or
reduce such harm even if some of the
cause and effect relationships have not
been fully established scientifically
• Basis of the Convention on Biological
Diversity
• 3 Q’s
Interesting Cases
• California Condor
• Southern Sea Otter
• Vultures/wild dogs/rabies
• Honeybees