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– 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– 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– 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