The Diversity of Life

by Edward O. Wilson

Part One: Violent Nature, Resilient Life

Storm over the Amazon
   key to the maintenance of the world
Island biogeography & succession
Great Extinctions
Five major "impoverishments"

Part Two: Biodiversity Rising

The Fundamental Unit

                   Energy & Biomass pyramids
New Species                                       
Evolution: cumulative adaptations


Forces of Evolution

                         natural selection & genetic drift
Adaptive Radiation
                          spread of species into open “niches”
The Unexplored Biosphere
                       “peculiar partnerships”
                                                                                symbionts & “coevolution”
The Creation of Ecosystems                    
context - history - chance
                                                                                "keystone species," need for predators
Biodiversity Reaches its Peak
       "Nature is always too devious"

Part Three: The Human Impact

Life & Death of Species
   demography, extinction, Picoides
“tender trap of . . . opportunism”


Biodiversity Threatened

  climate, deforestation, agriculture ---- S = CAz, 6th mega-extinction


Unmined Riches         
narrow utilitarianism vs. bio-sustenance
                                                                              commodity, amenity, & moral values
   material - cultural - biological wealth
                                                                                   identify, protect, create, restore
The Environmental Ethic
   "a common vocabulary, the nucleic-acid code"

Overview of the book

"Wilderness is a metaphor of unlimited opportunity. . . . not just the body but the spirit"

"Organisms are all the more remarkable in combination."

Two significant natural aspects are:

marshes, estuaries, wetland forests, seagrass beds
rain forests, coral reefs, edge effect where two ecocommunities overlap

These two characteristics are based on:

        1. fortune,
        2. adaptive radiation,
        3. niche exploitation,
        4. resource allocation or partition,
        5. generalist behavior, or
        6. symbiont coevolution.

Examples of coevolving keystone species

Corals {plant & animal}
forest & tundra
Lichens {plant & fungus}
Termites {animal & bacteria}

Current threats to biological wealth are:

Storm over the Amazon

Violent nature: resilient life are contrasted in order to convey the tensions between environmental resistance and biological or biotic potential.

Scene is the Amazon River basin

"one of the great surviving wildernesses of the world, stretching 500 kilometers." of uninterrupted forest cover


"This is the assembly of life that took a billion years to evolve. It has eaten the storms -- folded them into its genes and created the world that created us. It holds the world steady."

(15) , [¶ 38 in Walker, p. 160.]


"Life is out there in unexpected abundance....Ninety-nine percent of the animals find their way by chemical trails laid over the surface, puffs of odor released into the air or water , and scents diffused out of little hidden glands, and into the air downwind. Animals are masters of this chemical channel, where we are idiots."

[¶ 3 in Walker, p. 152.]

"reflections from the eyes of wolf spiders…on the prowl for insect prey."

"I needed to concentrate for only a second and they came alive as eidetic images, behind closed eyelids, moving across fallen leaves and decaying humus."

[¶ 6 in Walker, p. 153.]

"The best of science doesn't consist of mathematical models and experiments,.... Those come later. It springs fresh from a more primitive mode of thought, wherein the hunter's mind weaves ideas from old facts and fresh metaphors and scrambled crazy images of things recently seen. To move forward is to concoct new patterns of thought, which in turn dictate the design of the models and experiments."

"There is another way to look at an ant colony. ...They are a living web cast out by the superorganism, ready to congeal over rich food finds or shrink back from the most formidable enemies."

"we have problems to solve, we have clear answers--too many clear answers."

"The wind freshened, and the rain came stalking through the forest."

"jaguars walked the river's edge; around them eight-hundred species of trees stood, more than are native to all North America; and a thousand species of butterflies, 6 percent of the entire world fauna, waited for the dawn."

"The unresolved mysteries of the rain forest are formless and seductive."

[¶ 16 in Walker, p. 155.]

"The rain forest in its richness is one of the last repositories on earth of that timeless dream."

"There is still more to the study of biological richness.... Our goal is to capture and label a process, perhaps a chemical reaction or behavior pattern driving an ecological change, a new way of classifying energy flow, or a relation between predator and prey that preserves them both, almost anything at all."

"Why are there so many species? Why do birds sing at dawn?"

"Most ideas are waking dreams that fade to an emotional residue."

The conversion [of an idea into a scientific discovery] is an art aided by a stroke of luck in the minds set to receive them."

"It is diversity by which life builds and saturates the rain forest. And diversity has carried life beyond, to the harshest environments on earth."

"Life is too well adapted in such places, out to the edge of the physical envelope where biochemistry falters, and too diverse to be broken by storms and other ordinary vagaries of nature."

[¶ 35 in Walker, p. 160.]

"But the restorative power of the fauna and flora of the world as a whole depends on the existence of enough species to play that special role. They too can slide into the red zone of endangered species."

[¶ 36 in Walker, p. 160.]

"Biological the key to the maintenance of the world as we know it."

[¶ 37 in Walker, p. 160.]

"how much force does it take to break the crucible of evolution?"

Biological wealth as a hedge against loss of natural capital


volcanic creation of habitat (places & inorganic features)

spiders are among the earliest terrestrial life on deserted islands

"The thick green forest offers testimony to the ingenuity and resilience of life. Ordinary volcanic eruptions are not enough, then, to break the crucible of life." (23)

The Great Extinctions

5 or 6 mass extinctions have sculpted the biota we see

"I have begged the question of ultimate causation. If global cooling was the killing event, what caused the cooling?

… " the movement of land masses "

"Today the land mass of the world is arrayed in a configuration that favors high levels of diversity: widely separated continents with long shorelines and stretches of shallow tropical water dotted with lots of islands."

Time required for the recovery from a mass extinction:

0 = state of widespread biotic differences among creatures and within species

5 million years = the initial period

20 million years = minimal time for complete recovery of preexisting biodiversity

30 million years = recovery for oceanic extinctions (Devonian)

100 million years = recovery for Permian & Triassic destruction due to frequency

Recovery is a slow laborious process of trial and error, fortunes and foibles.

"These figures should give pause to anyone who believes that what Homo Sapiens destroys, Nature will redeem.

… Within any length of time that has meaning for contemporary humanity."


species are the accounting medium of macro-biology

species, the fundamental units, each playing a unique role in relation to the whole." (35)

"The hallmark of life is this: a struggle among an immense variety of organisms weighing next to nothing for a vanishingly small amount of energy."

"Life operates on only 10% of the sun's energy reaching the earth's surface, that portions fixed by the photosynthesis of green plants."


"The free energy is sharply discounted as it passes through the food webs from 0ne organism to the next:"

Top carnivores …. always … skirt the edge of extinction and they are the first to suffer when the ecosystem around them starts to erode."


"biological diversity is a side product of evolution"

What is the origin of biological diversity?

1859 - "or the Preservation of favoured Races in the Struggle for Life."

Evolution creates two patterns across time:

vertical change w/in the original population

-- Homo erectus ------> Homo sapiens

speciation & vert. chg. -- adaptive radiation ++ A. robustus; Homo habilis, erectus

"A species can be altered so extensively by natural selection as to be changed into a different species, said Darwin."

speciation's relation to global diversity

"In conclusion, species can be created quickly, and diversity can therefore expand explosively. Our knowledge of evolution, though imperfect, tells us at the very least why life has that potential. Given the right circumstances, a new species can arise in one to several generations."


“…new species are relatively cheap species.
" If they fill a new niche, they probably do so with relative inefficiency."       


"Great biological diversity takes long stretches of geological time and the accumulation of large reservoirs of unique genes. The richest ecosystems build slowly, over millions of years."

" It is further true that by chance alone only a few new species are poised to move into novel adaptive zones, to create something spectacular and stretch the limits of diversity. A panda or sequoia represents a magnitude of evolution that comes along only rarely. It takes a stroke of luck and a long period of probing, experimentation, and failure. Such a creation is part of deep history, and the planet does not have the means nor the time to see it repeated."                                                                                                                                                        (74)

The Forces of Evolution

genes are the accounting medium of micro-biology

"One gene can change the shape of the skull. It can lengthen lifespans, restructure the color pattern on a wing, or create a race of giants."

Changes in the frequency of gene and chromosome combinations among populations are the underlying motive power of evolution.

a gene -- is a portion of the nucleotide, DNA, that codes for a specific protein

Chromosome 20 of the human genome wherein the genes lie for certain proteins to be built ...

point mutation -- a piece of the nucleotide bases is randomly substituted by another

natural selection -- acts on genetic [genotype (raw) & phenotype (environs)] matter

genetic drift -- random (chance) changes in the gene frequencies of populations

Darwin (1859) was unaware of Mendel's work (1865)

Darwin's theory requires:

                1) variation in traits (eye color) exist across any population

                2) the inheritability of traits from parents to offspring

                3) differential reproductive success among individual offspring


What Drives Evolution?

"There are other causes of evolution but natural selection is overwhelmingly dominant."

"This is the question that Darwin answered in essence and twentieth century biologists have refined to produce the synthesis, called neo-Darwinism, with which we now live in uneasy consensus." (75)

"The fundamental evolutionary event is a change in the frequency of genes and chromosome configurations in a population."

"Individuals and their immediate descendants do not evolve. Populations evolve, in the sense that the proportions of of carriers of different genes change through time. This conception of evolution at the population level follows ineluctably from the idea of natural selection, which is the core of Darwinism."

"There is still a great deal more to evolution than its genetic mechanisms."


"How important is species selection? If the group is defined broadly enough, such as all vascular plants or all land vertebrates, it is of overwhelming importance."


"Among insects, a shift from predatory behavior or scavenging, to plant feeding increases the rate of species formation."

(coveolution of flowers & insects)

Adaptive Radiation

the rise, spread, decay and fall of species reveals patterns

"Organisms possessing a common ancestry rise to dominance, expand their geographic ranges, and split into multiple species."


"A complex and strikingly beautiful pattern across the surface of the earth… a palimpsest … as past {species} survive as faded traces…."

AR is the spread of related species (individuals that may interbreed successfully)

into a wide variety of open or unoccupied niches over evolutionary time.

a niche is the fundamental unit of ecological adaptive "5" face="Arial, Helvetica, sans-serif">

        role, function, place, range, habits & "job" of an organism throughout its life.

        hypervolumetric niche: amount of energy transformed into matter in a specifc space over a given time by an organism

AR accounts for:

       Poaceae (flowering plants) -- grasses; comprise 80% of the human diet

       Galapagos island's Finches (Darwin) 13 species

       300 species of Cichlid fishes & 350 species of sharks (both endangered)

The Unexplored Biosphere

almost half of all species on earth are Arthropods!

there are 290,000 known species of coleoptera! [beetles]

they pollinate primitive flowers & recycle organic (waste) nutrients

Is our world maintained by arthropods (invertebrates, insects, crabs, spiders, etc.?

What would happen to vertebrate & fungal populations if arthropods become extinct?

We know between 10% & 1.4% of all probable species on earth (labor intensive)


        1 Gram of Soil

bioceonose: 10 billion bacteria representing 4,000 to 5,000 known bacterial species

What are the five kingdoms (macro-divisions) of life?

(make an analogy to a hand)

Three measure of diversity:

alpha -- species richness in a particular habitat
beta  -- rate of increse in the number of species as habitats are added
gamma -- number of species in all habitats across a wide area (sp. equitability)

Creation of Ecosystems

accidental vs. perfect order of predators & prey

keystone species        

enhydra lutris, the California Sea Otters

They eat echinoderms or sea urchins. The sea urchins eat at the kelp (brown algae) forests base supports called "holdfasts." Hence anything that diminishes the number of sea urchins allows more kelp strands to grow, thereby adding to the density of the underwater forest.

"In the study of communities, this strategy requires greater attention to context, history, and chance."

resource partitioning (172)

Finches & character displacement

predation & pisaster


commensals & symbiosis


Chance, life, & inheritance play roles in maintaining life

An ecosystem combines the habitat (inorganic) with the biotic community (organic) parts of any place, area, or region.

Over evolutionary (20 genertaions or more) time ecosystems change due to biotic and abiotic factors that affect the differential survival rates of all individuals.


key individuals may affect the character of the ecosystem: starfish, Pisaster *see 3

Sea Otters in Pacific coastal kelp beds

Elephants & driver ants (probably leaf cutter ants in the Rain Forests of Americas)

Gopher Tortoises in Florida sand & scrub habitats; alligators in seasonal swamps

Assembly (of life) rules:

1) specialized predator prey

2) competitive exclusion: no two species can occupy the same niche simultaneously

3) checks

Complexity of biotic communities increases over time due to symbiosis:

[living together] coral reefs, lichens (tundra & forest), termites, mycorrhiza.

3 types of symbiosis are:

  1. Mutualism (E. coli),
  2. commensalism (tilandsia),
  3. parasitism (plasmodium).

Food webs and chains of dependency reveal how little we know about communities!

"In the study of communities, this strategy requires greater attention to context, history, and chance."

Biodiversity Reaches the Peak

Diversity is, in one restricted sense: the variety of species throughout the earths' many habitats

Life may actually regulate the atmosphere of the planet.

"The most wonderful mystery of life may well be the means by which it created so much diversity from so little physical matter. The biosphere, all organisms combined, makes up only about one part in ten billion of the earth's mass."

"Yet life has divided into millions of species, the fundamental units, each playing a unique role in relation to the whole." (35)

ecosystem is a collection of biotic communities (organic features of a place) +

collection of habitats (inorganic features of a place)

existing dynamically over time due to the reuse of scarce nutrients & materials by either:

           cooperating -- symbiotic or,

           competing -- rival organisms (creatures, life, beings).

Biodiversity is due to:

1) habitat differences,
2) species richness,
3) genetic variety


Great extinctions created these grand sweeps of prehistory:

age of fishes; the Devonian
405 mi. years ago
age of insects; the Carboniferous
310 mi. years ago
age of reptiles; the Mesozoic
230 mi. years ago
age of mammals; the Cenozoic
60 mi. years ago
age of primates; the Plio-pleistocene
2 mi. years ago

For comparison to the above time periods consider:

540 mil. years ago oxygen levels > to comprise the current 21% of air!

450 mil. years ago the first plants colonized the dry land; insects followed

Should ours, instead, be the age of ants? (they farm, build nests, & recycle)

small animals are more diverse than large

Area is required for diversity to increase & not decrease over time:

640 acres = 1 square mile or 250 hectares

100 hectares = 1 square kilometer

                10,000 Hect. = 25,000 Acres = ?

Little known bio-trivia:

ants constitute the largest animal biomass in ecosystems

Arthropoda are the greatest bulk of living creatures on Earth.

The Life and Death of Species

endangered species, speciation & fragmentation

Two approaches to life's diversity:

ecological stage -- the quest for habitat, sustenance, security, comfort, procreation, the life cycle, range, longevity, gestation, and generational quality biogeographical dispersal of populations arena of the tangled bank {interdependencies are manifold }

evolutionary stage -- the biogeochemical heritage as encoded in DNA & RNA

                               inheritable traits, reflexive behavior

                               historical accidental character

genetic, biogeochemical and biogeological heritage all come together in the DNA: red and yellow is the sugar phosphate chain on which the blue nitrogen bases hang.

Life & Death Species

Island biogerograhy

Manaus forest fragments

Kirtland's warbler & Red cockaded woodpecker have isolated territories now due to fragmentation of their habitat.

binocular vision reveals the totality & depth perception of a viewpoint

              there & then…

                     … here & now

EXTINCTION means that species persist for only millions of years, then perish

Pre-Cambrian extinctions -- Burgess shale formation of Canada

Cambrian explosion of diversity (seas) -- may have been more diverse than now.

Ordovician -- first worldwide ecosystem collapse, cessation of reef building!

Devonian -- another worldwide collapse -- end of reef building, 90% extinction.  terrestrial flora & fauna emerge

Permian -- 54% of the families perished; 77-96% of all marine organisms it took over 10 million years for reef building organisms to rebound!

Cretaceous -- 1/3 of all families perished; dinosaurs, trilobytes, & ammonites gone

                     60% of all species perished

Pleistocene -- large animals died out: saber toothed tigers, mammoths, & sloths

Rephrasing Darwin's argument:

natural & sexual selection + genetic drift = varied descent

specialized forms in narrow niches are exterminated during mass extinctions

Common errors in thinking about evolution by means of natural selection:

            humans are descended from apes (your cousins are not your parents!)

            individuals do not evolve (species are descendants of common ancestors)

            differential survival of competing or cooperating individuals is purposeful

            favored races dominate "weaker" strains due to natural laws

            natural selection is the exclusive shaper of the most "fit" traits

Darwin's argument for evolution was: deductive, inductive, analytical & synthetic:

analysis of the anomalous fossil record (sea creatures in the Andes!)

            deductive analysis of variation in artificial selection (roses, horses, cats)

            synthesis of deductive findings in biogeographical patterns (grasslands) 

            analysis of niches filled by different yet equivelant species (kangaroos)

            inductive argument about finches, iguanas, tortoises adaptive radiations

            synthesis of variation and the population pressures derived from Malthus

            inductive argument about time, biogeography, stratigraphy & population

what ought we to know & how are we to behave?

"We live on a largely unexplored planet"

"a common vocabulary, the nucleic-acid code"

"Wilderness is a metaphor of unlimited opportunity. . . . not just the body but the spirit."

economic value of biodiversity

90% of the world's food comes from 20 plant species!

Roles of certain coevolving keystone organisms in global biogeochemical cycles convert material that interconnect:

WEAL as an acronym for features of a habitat




A Schematic diagram of the geochemical elements associated with Water, Energy, Air, and Land that act as limiting factors in the "machinery of nature."

Review of chapters

Communities on earth whose ecosystems are maintained by symbiotic creatures

70% of the planet is water
Corals {plant & animal}
calcium carbonate precipitation
carbon regulation sink

30% of the planet is terrestrial

forests & tundra

Lichens {cyanobacteria, algae, & fungus}

nitrogen & carbon cycles

mycorrhiza {fungus & plant}
orchid, azalea, pine
nitrogen & phosphorus roots
Termites {animal & bacteria}
methane & temperature

Adaptive Radiation

Cychlids -- Nile Perch (oily) -- Trees, fire, erosion,

problem with exotics due to predation


relative abundance exists on a series of interlocking scales:

Ecosystem --community --guild --species --organism --gene

Biodiversity Peak

great extinctions: age of fishes; age of insects; age of reptile;

age of mammals; age of primates

Biodiversity Threatened

overkill, habitat destruction, exotics, & disease

"I can not imagine a scientific problem of greater importance for humanity, than the loss of biodiversity." (254)

Unmined Riches

Biodiversity is our most valuable but least appreciated asset, or feature of our natural capital

"Its potential is brilliantly illustrated by the maize species Zea diploperennis, a wild relative of corn discovered in the 1970s by a Mexican College student in the west central state of Jalisco, south or Guadalajara."

The new species is resistant to diseases and unique among living forms of maize in possessing perennial growth.

The Jalisco maize was found just in time, however. Occupying no more than 10 hectares (25 acres) of mountain land, it was only a week away from extinction by machete and fire."

permanent loss of genetic information means a loss on information on past ecological conditions

Charles Darwin

Wrote about the birds he had collected in the Galapagos archipelago, that:

"The most curious fact is the perfect gradation in the size of the beaks."

Galapagos     Volcanic islands 631 miles from Ecuador

family: Geospizinae    600 specimens of 2 species of finches on Dafne Island

1) Natural Selection:         climatic or geological changes

                                      1977-78 drought 555 days w/o rain

    competition for scarity (seeds) number available for birds

    birds turn their attention to larger seeds in drought (xeric tolerant plants)

          (small bills are selected against the large beaked birds are selected for)

          large beaked finches' population increases

Medium ground finch has hydridized with other finches and has a wider range of beak variability -- after two generations the size of the beak became enlarged.

1983 severest El Nino in 400 years (3 times the rain as worst rains, 8 months)

Finches bread rapidly (8 broods in 10 months; 150 to 1000 birds) small beak spread

After the wet years the smaller species grew; drier years the larger species grew

"Population size is critical to genetic drift"


Every country has three forms of wealth

"the substance of our every day lives:"

1) material -- capital, resources, money, consumer goods, inventories, structures.
2) cultural -- public places, food, medicine, religious shrines, museums, amenities.
 "is passing through a bottleneck:"
3) biological -- species, biotic communities, soil, reefs, plant asociations, fungi nitrogen fixing bacteria, gene pools, or
"Vavilov centers" (ch. 13)
Sustainable development -- minimize extinction rates while minimizing costs
Conservation International
BIOTROP - identify ecological hot spots in danger of loss
designing reserves
             protect & sustain indigenous peoples
             encourage extractable resources (cashews, mushrooms, rubber, drugs)
             restoration ecology -- recreate biological wealth
bioregions & characteristic ecosystems to be protected to preserve keystone species

"beauty arises from error."

"a change in the frequency of genes and chromosome configurations in a population."
"The number of genes in a typical larger organism, such as a human being, is on the order of 100,000."
"At least genes on different
chromosome positions affect
variation in quantitative traits
such as the date of flowering
in plants, fruit size, the eye
diameter of fish and skin color
of human beings. As many as
100 genes work together to
prescribe traits as complex as
ear structure or skin texture."

"Evolution unfolds–like much of human history."

Humans are part of nature

Nature's past is enfolded into our genetic "blueprint"
The special qualities of humans arise from:
                 descent (inherited traits)
                        genetic drift (chance -- statistical variation)
                        sexual selection (female choice ?)
                 environmental resistance (natural selection)
                 social animals
                        herd instinct
                 culture (acquired traits)
                          behavioral norms
Nature selects for the "luckiest" generalists w/o intervention