Lecture 2 evolution and ecology
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Lecture 2: Evolution and Ecology EEES 3050 Excerpt from The Voyage of the Beagle (1845) It is probable that the islands of the Cape de Verde group resemble, in all their physical conditions , far more closely the Galapagos Islands…

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Excerpt from the voyage of the beagle 1845 l.jpg
Excerpt from The Voyage of the Beagle (1845)


Slide3 l.jpg


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Natural diversity l.jpg
Natural Diversity unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • By the Numbers –

    • Estimated 2 - 100 million species, with a best estimate of somewhere near 10 million

    • ~1.4 million described species

    • ~1 million described insects/ 350,000 described beetles

    • 8,800–10,200 living bird species

    • ~5,500 species of mammals

  • Great diversity exists, with each species exhibiting a considerable degree of suitability for its natural lifestyle

    • How?

    • Seems unlikely


Evolution disclaimer l.jpg
Evolution Disclaimer unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Whether you choose to believe that evolution is the means by which existing species diversity developed or not, you are responsible for learning and applying the principles in this course.

  • In short: “This course will be taught from the evolutionary paradigm.”


What do scientists do l.jpg
What do scientists do? unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Explain

  • PREDICT!

  • Need a theory to make predictions.


Other major scientific theories l.jpg
Other major scientific theories. unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Cell theory – 1839

  • Plate tectonic theory – not fully accepted until late 1960’s

  • General relativity (i.e. gravitational theory) – proposed by Einstein in 1915/16.

    • Gravitational waves are a requirement of the theory of general relativity, but have never been directly detected

      • Gravitational waves have been generally been accepted to exist since 1980s.

  • Chemistry – Valence bond theory and molecular orbital theory

    • Competing theories in the 1930s. Now somewhat combined – also the advent of quantum chemistry.


What is evolution l.jpg
What is evolution? unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Broad: The gradual process by which the living world has been developing following the origin of life.

  • Narrow: Change in the genetic frequencies of a population.


What evolution is by ernst mayr l.jpg
What Evolution Is? unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.By Ernst Mayr

  • “Evolution is the most important concept in biology. There is not a single Why? question in biology that can answered adequately without a consideration of evolution.”

  • Again need theory for explanation and prediction.


Why is the theory of evolution important l.jpg
Why is the theory of evolution important? unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Implications for people:

    • Antibiotic resistance, pesticide resistance, control of disease, human epidemiology, development of new crops, medical treatments, conservation biology, etc. (not to mention the ecological implications)

  • Evolution provides the mechanism to address these issues.


Historical background early contributors l.jpg
Historical Background: Early contributors unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Lamark (1809): Inheritance of Acquired

    • Characteristics (learning; meme vs. gene)

  • Darwin: Theory of Evolution (Origin of Species 1859)

    • 5 theories really.

    • Malthus: potential usually exceeds realized reproduction for populations (including humans)

  • Wallace: independent conceptualization of Natural Selection

  • Mendel: Genetics = currency of evolution


Historical background biological issues l.jpg
Historical Background: Biological issues unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • In 17th Century and prior:

    • Natural history

      • Segregated into zoology and botany

    • Medicine

      • Segregated into anatomy, physiology, surgery, and clinical medicine.

  • Evolution and genetics unified all these disciplines.


Historical background l.jpg
Historical Background unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

  • Darwin’s Five Theories

    • 1 – The non-constancy of species

      • The idea of a changing world can be considered the fact of evolution.

  • 2 – The descent of all organisms from common ancestors

  • 3 – Gradualism (no saltations, no discontinuities)

  • 4 – Speciation by populations

  • 5 – Natural selection

    • This is the “theory” of the process of evolution.


  • Historical background15 l.jpg
    Historical Background unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Darwin’s Five Theories

      • The non-constancy of species & common ancestors

        • Quickly accepted

      • Gradualism, speciation and natural selection.

        • Not completely accepted until 1940’s


    Slide16 l.jpg

    Evidence for evolution unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Fossil Record

    • Morphology

    • Vestigial organs

    • Biogeography

    • Molecular evidence


    Evidence for evolution fossil record l.jpg
    Evidence for evolution: Fossil record unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.


    Evidence for evolution fossil record18 l.jpg
    Evidence for evolution: Fossil record unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Jaw bone evolution from therapsid reptiles to mammals.


    Evidence for evolution fossil record19 l.jpg
    Evidence for evolution: Fossil record unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Evolution through time:

    • Variation through geologic periods.

      • Fossils in most recent strata are often similar if not indistinguishable from living species.

      • The older the strata is, the more different the fossils.


    Evidence for evolution l.jpg
    Evidence for evolution unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Morphology:

      • This was how species were described as “related” as far back as 18th century.

      • Linnaean hierarchy:

        • From Kingdom to sub-species


    Evidence for evolution21 l.jpg
    Evidence for evolution unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Vestigial Structures:

      • Structures that are not fully functional or functional at all.


    Evidence for evolution22 l.jpg
    Evidence for evolution unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Vestigial Structures

      • Blind cave dwelling animals still have eyes (that don’t work).

      • Why does an ostrich have wings?


    Evidence for evolution biogeography l.jpg
    Evidence for evolution: Biogeography unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Biogeography:

      • the geographic distribution of organisms

    • those [organisms] of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.


    Evidence for evolution biogeography24 l.jpg

    Evolution through space: unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    Evidence for evolution: Biogeography


    Slide25 l.jpg

    Gondwana unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.


    Evidence for evolution26 l.jpg
    Evidence for evolution unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Molecular evidence

      • the more closely related two organisms are, the more similar are their genetic structure.

      • Often times, morphological traits can be ambiguous.

      • One of the most important sources of information on phylogenetic relationships


    Mendelian genetics l.jpg
    Mendelian genetics unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Gregor Mendel: 1822 – 1884

      • What did Mendel do?

      • Example: Green and yellow peas

    Mendelian genetics was originally used to dispute one of Darwin’s theories.


    Maintaining genetic variation see appendix l.jpg
    Maintaining Genetic Variation – See appendix. unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Without Selection: no loss or gain (random)

    • B. Hardy-Weinberg Theorem: constant allelic frequencies are maintained if ...

      • populations are large,

      • individuals contribute equally to genetic composition of next generation, and

      • matings are random

    • Remember: Narrow definition of evolution = change in the genetic frequency of a population.


    Why does this matter l.jpg
    Why does this matter? unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • If population is not at equilibrium –

      • There are outside forces acting on the population.


    Outside forces that can change population genetics l.jpg
    Outside forces that can change population genetics. unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Mutations

      • origin of variations, and mutation increases under stress

        • Age, chemicals, UV-radiation

    • Migration

    • Population size

    • Non-Random Mating

      • Nonrandom Mating: ∆ gene frequencies

      • Environmental Variance: favor some phenotypes

      • Effects of Selection: stable polymorphisms

  • Natural Selection


  • Loss of genetic variation l.jpg
    Loss of Genetic Variation unlike; those of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

    • Inbreeding: rapid loss of genes

      • Fixes traits quickly

    • Genetic Drift: random losses of genes

    • Neighborhoods: local breeding tendency

      • Races of plants and animals

    • Bottlenecks: low population = reduced pool, duration of the low population is critical (drift)



    Current evolution l.jpg
    Current Evolution 10,000 years ago.

    • According to narrow definition:

      • Evolution is little more than a process that changes gene frequencies in a non-random manner;

      • environmental influences direct this change

    • What are a few examples of recent evolution of species that can be correlated to an environmental stress?


    Examples l.jpg
    Examples 10,000 years ago.

    • The evolution of pesticide resistence in pest species

    • The evolution of antibiotic resistence in human pathogens

      • note the recent discovery of plague and tuberculosis exhibiting broad-spectrum antibiotic resistence



    Strep resistance to penicillin l.jpg
    Strep 10,000 years ago.resistance to penicillin


    Maintenance of variation l.jpg
    Maintenance of variation 10,000 years ago.

    • So how is variation maintained in the face of environmental pressures and natural selection?

      • Ever see a constant environment?

      • Microenvironmental differences exist over small spatial scales.

      • Temporal heterogeneity is a common characteristic of physical environments.


    Evolutionary ecology l.jpg
    Evolutionary Ecology 10,000 years ago.

    • Fusion of ecology and evolutionary theory.

    • Sometimes two terms used as different time scales.

    • An observed relationship may be explained by:

      • functional, proximate or “ecological” means.

      • Or ultimate, evolutionary terms.

    • Historically, ecologists assumed many phenomena are immutable:

      • Sex ratios (always 50:50), generalist vs. specialist feeding preferences, migration, number of offspring.

        • An evolutionary perspectives recognizes these phenomena change through time and in response to the environment.


    Evolutionary ecology39 l.jpg
    Evolutionary Ecology 10,000 years ago.

    • Evolution is a primary factor in determining the distribution and abundance of organisms.

      • A relatively new field (last 25 year).

      • Thus not adequately addressed in most text books.


    Slide40 l.jpg

    • “There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”

      • Charles Darwin – The Origin of Species (Last sentence)


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