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Vertebrate Zoology

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Title: Vertebrate Zoology


1
Vertebrate Zoology
  • Dr. A. Kristopher Lappin is attending themeeting
    of the Society for Comparative and Integrative
    Biology (Seattle, WA).
  • He will return Friday, January 8.
  • Dr. Moriarty, Biological Sciences
    Dept.Biostatistics, Population and Community
    Ecology, Ornithology

2
Vertebrate Zoology
  • Introduction Dr. A. Kristopher Lappin
  • Blackboard Site
  • Lecture Lab
  • check regularly (also Cal Poly e-mail)
  • PP presentations, notes, lab assignments, etc.
    posted there but not handed out
  • Language / Vertebrate Zoology Analogy
  • Principles of Evolution

3
Goals of Course
  • to develop of basic understanding of the
    evolution, diversity, anatomy, physiology,
    behavior, ecology, natural history of
    vertebrates
  • to gain an appreciation for vertebrate life
  • to develop an ability to share your appreciation
    knowledge of vertebrates w/ others during this
    critical time in human history

4
Definitions of Biological Disciplines
  • evolutionchange through time
  • biodiversityvariety of living forms their
    habits
  • anatomy physiologystructure function
  • behaviorhow animals do things
  • ecologyinteractions of animals w/ each other
    their physical environments

5
Some Biological Levels of Organization
  • how molecules w/in cells interactmolecular
    biology
  • how cells functioncell biology
  • how tissues/organs of an individual organism
    function interactphysiology

6
Some Biological Levels of Organization
  • how individuals w/in a species interactpopulation
    biology
  • intraspecific level
  • how different kinds of organisms
    interactcommunity ecology
  • interspecific level
  • Relate levels of organization when comparing
    organisms to better understand evolutionary
    trends.

7
What is a theory?
  • hypothesis / set of hypotheses that provide a
    powerful explanation for a variety of related
    phenomena are supported by overwhelming
    evidence
  • purpose is to guide scientific inquiry
  • Gravity is a theory.
  • Evolution is a theory.

8
Theory of Evolution
  • establishment of Evolution as a scientific theory
  • Charles Robert Darwin
  • Alfred Russel Wallace
  • developed theory of natural selection
    independently
  • Darwin published On the Origin of Species (1859)

9
Influences on Darwin
  • Lamark
  • first scientific explanation of evolution
  • inheritance of acquired characteristics
  • made case that fossils are remains of extinct
    animals
  • Lyell
  • uniformitarianismsame physical laws geological
    processes operate now as during Earths history

10
Influences on Darwin
  • voyage of the H.M.S. Beagle
  • Darwin 23 years old
  • 5-year voyage around the world

11
Influences on Darwin
  • observed collected fauna flora
  • found fossils
  • found seashells in mountains at 4,000 meters
  • experienced major earthquake in S. America

12
Influences on Darwin
  • Beagle stopped at the Galapagos Islands (on
    equator 600 miles off of W coast of S. America)
  • spent 5 weeks on islands

13
Influences on Darwin
  • Galapagos visit hugely influential on Darwins
    development of theory of evolution
  • organisms unique, yet similar to continental
    forms in S. America (e.g., giant tortoises due to
    lack of predators)

14
Perpetual Change Geological Time
  • Perpetual geological biological change is the
    rule.
  • Consider the vastness of geological time.
  • radiometric dating
  • age of Earth4.6 billion years

15
Evidence of Perpetual Change
  • Banded Iron Formation, Australia
  • rocks up to 3 billion years old

16
Evidence of Perpetual Change
  • Big Island, Hawaii
  • oldest part of island 400,000 years old (7,500
    times younger than the old rocks)

17
Fossil Record
  • oldest microscopic fossils3.5 billion years
  • oldest macroscopic fossils650 million years
  • most animal phyla present 540 million years ago

18
Fossil Record
  • Burgess Shale (580 million years old Cambrian)
  • many phyla present that are long extinct
  • some modern phyla represented
  • an experiment of evolution

19
Fossil Record
  • oldest vertebrates gt500 million years old
  • human agriculture 10,000 years old
  • Therefore, human agriculture is about 0.00002
    (two one-hundred thousandths of one per cent) as
    old as the oldest vertebrates
  • 0.00002 of a mile 1/3 of a millimeter

20
Fossil Record
  • 99.9 of all metazoan species that have ever
    lived on Earth are extinct
  • of these estimated lt 0.1 of animal species have
    been discovered as fossils

21
Fossil Record
  • estimated that one in 10 million individual
    organisms end up as fossils
  • variable among taxa depending on presence of hard
    parts
  • What we know about past life on Earth (which is a
    lot) is based on a tiny sample.

22
Common Descent
  • all forms of life ultimately descended from a
    common ancestor via a branching of lineages
  • single origin of life
  • overwhelming evidence (e.g., organismal form,
    cell structure, development, DNA)

23
Common Descent Phylogeny
  • structure of life is like a treephylogeny

common ancestor of ratite birds
24
Common Descent Homology
  • same organ in different organisms under every
    variety of form function (Owen)
  • e.g., limb skeleton of tetrapods from salamanders
    to humans share homologous elements

25
Common Descent Homology
  • homologous structures reflect common evolutionary
    ancestry
  • homologous structures used to generate
    phylogenetic hypotheses of relationships among
    organisms
  • structures can be macroscopic or at the
    molecular level (e.g., proteins, DNA)

26
Common Descent Homology
  • Whether or not two structures are homologous
    depends on the level being considered.
  • E.g., bird wing bat wing grossly homologous
  • modified forelimb
  • but specific elements supporting the airfoil of
    each are not homologous
  • feathers in bird vs. skin in bat

27
Common Descent Homology
28
Analogy
  • similar structures that serve similar function
    but do not indicate common ancestry
  • e.g., bird wing vs. butterfly wing

29
Cladistics
  • cladogramdiagram of relationships among groups
    (like a phylogeny) generated using a specific
    methodology (i.e., cladistics)

30
Phylogenetics Cladistics
  • cladegroup sharing derived character states
  • e.g., Squamata (lizards, snakes, amphisbaenians)

Squamata (squamate reptiles)
31
Phylogenetics Cladistics
  • relationships are reconstructed based on shared
    derived characterssynapomorphies

synapomorphy defining squamates w/in amniotes
32
Phylogenetics Cladistics
  • synapomorphies must be homologous characters
    across taxa in a clade

synapomorphy defining squamates w/in amniotes
33
Phylogenetics Cladistics
  • shared ancestral characters do not define a clade
  • e.g., diapsid skull does not distinguish
    squamates as a group distinct from other diapsid
    amniotes

ancestral for squamates w/in amniotes (b/c also
shared w/ outgroups to squamates)
34
Phylogenetics Cladistics
  • polaritydirectionality of ancestral/derived
    condition among groups (outgroup comparison)
  • e.g., presence of teeth is ancestral for amniotes
    therefore lack of teeth is derived for birds
  • lack of teeth is a synapomorphy for birds

teeth absent
teeth absent
teeth present
35
Phylogenetics Cladistics
  • in reality, branch tips represent species (lowest
    level non-reticulating lineage)
  • for illustration, branch tips can represent
    higher level taxa (e.g., genera, families,
    classes, orders)

36
Phylogenetic Systematics
  • names of taxonomic groups based on identification
    of monophyletic groups ( clades)
  • monophyletic groupancestor all descendents
  • paraphyletic groupancestor some descendants
  • polyphyletic groupcommon ancestor not included

teeth absent
teeth absent
teeth present
37
Phylogenetic Systematics
  • EXAM PREPARATION Come up w/ examples of each of
    these types of groupings. Be able to explain
    your answer. Feel free to come to office hours
    for help.

teeth absent
teeth absent
teeth present
38
Multiplication of Species
  • well-accepted, but mechanistic details under
    constant study (as is the way of science)
  • evolution produces new species by the splitting
    transformation of existing species
  • What is a species?

39
What is a species?
  • Biological Species Concept (Mayr 1940)
  • an interbreeding natural population (or group of
    populations) that is reproductively isolated from
    other such groups
  • Evolutionary Species Concept (Simpson 1961
    Wiley 1981)
  • a single lineage of ancestral-descendant
    populations that maintains its identity from
    other such lineages that has its own
    evolutionary tendencies historical fate
  • at least 30 other published species concepts

40
Multiplication of Species
  • branch points (splits b/t lineages) on a
    phylogenetic tree represent speciation events
  • speciation formation of new species
  • Note Branch points also represent common
    ancestors that gave rise to descendant lineages.

41
How does speciation occur?
  • evolution of reproductive barriers
  • can be physical, physiological, ecological,
    behavioral, etc. (frequently a combination)
  • generally accepted that the evolution of
    reproductive barriers b/t populations of animals
    requires the presence of geographic barriers
    (e.g., mountain range, isolated island) that
    physically separate populations

42
How does speciation occur?
  • allopatric speciation
  • population separated into two separate groups by
    geographic barrier
  • followed by evolution of reproductive barriers
  • examples of geographic isolating mechanisms
  • formation of new mountain range separating
    population of low elevation species
  • formation of new island (e.g., land in ocean,
    lake on land) followed by rare immigration of
    individuals

43
How does speciation occur?
  • examples of allopatric speciation
  • marine iguana land iguana on Galapagos
  • reptiles on islands in Sea of Cortez
  • Hawaiian crow
  • squirrels on N S rim of Grand Canyon
  • other speciation mechanisms exist, but allopatric
    speciation is most pervasive

44
Adaptive Radiation
  • can arise from allopatric speciation
  • result evolution of many diverse species from a
    common ancestral stock
  • Darwins finches on Galapagos Islands
  • fruit flies on Hawaiian Islands
  • cichlid fish in African rift lakes
  • Anolis lizards on Caribbean Islands
  • elapid snakes in Australia
  • adaptive radiations typically associated w/
    invasion of areas w/ unoccupied habitats or
    niches (e.g., islands)

45
Adaptive Radiation
46
Gradualism
  • major differences in traits among species evolve
    by accumulation of many small incremental changes
    over time
  • somewhat controversial

phyletic gradualism
47
Gradualism
  • theory of gradualism argues against sudden
    appearance of new species rapid morphological
    changes
  • now accepted that new species can appear suddenly
    that rapid morphological changes can evolve

48
Alternative to GradualismPunctuated Equilibrium
  • sudden appearance of new species rapid
    morphological changes followed by long periods of
    stasis
  • some patterns show gradualism others indicate
    punctuated equilibrium
  • reality likely combination of both

punctuated equilibrium
49
Ontogeny Phylogeny
  • ontogenydevelopment of organism throughout life
  • knowledge of ontogeny helps w/ understanding of
    homology, common descent, phylogeny
  • alteration of development can generate novel
    phenotypes, which can result in big life history
    differences b/t organisms
  • difference b/t humans chimps in expressed genes
    are mostly developmental genes

50
Heterochrony
  • heterochronyevolutionary change in timing of
    development
  • can be broad
  • e.g., humans exhibit extended early development
    are born at an early stage
  • can be specific to certain structures
  • e.g., gills of axolotl retained throughout life

51
Natural Selection
  • proposed by Darwin (and Wallace)
  • supported by abundant evidence
  • describes how populations accrue favorable
    characteristics over evolutionary time
  • evidence from artificial selection
  • e.g., dog breeds
  • supported by series of observations inferences
    from those observations

52
Natural Selection
  • organisms have great reproductive potential
    many more are produced than can survive (Malthus)
  • populations fluctuate in size but do not show the
    continuous exponential increase that they would
    w/out some limitation
  • resources limited, so not all offspring can
    survive (Malthus)

53
Natural Selection
  • Inference struggle for existence among
    individuals in a population that increases w/
    greater numbers of individuals (Malthus)
  • all organisms show variation (random)
  • variation is heritable
  • e.g., you look act like your parents (or at
    least you will eventually)

54
Natural Selection
  • Inference differential survival reproduction
    among individuals
  • Inference differential survival reproduction
    generate new adaptations species
  • consider how natural selection could generate
    changes over geological time
  • artificial selection (breeding) generates radical
    changes in human lifetimes

55
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58
Evolutionary Concepts
  • convergence
  • reduction, loss, reversal
  • specialization

59
Convergence
  • independent evolution of a similar
    characteristic in two or more taxa
  • morphology, physiology, ecology, behavior,
    etc.often a combination
  • presence of similarity not due to common ancestry

60
Convergence
  • Lizards mice both have four limbs. Is this
    convergence?

61
Convergence
  • Lizards mice both have four limbs.
  • Is this convergence?
  • No
  • The presence of four limbs in both lizards
    mice is explained by common ancestry.
  • How do the terms homology, analogy,
    synapomorphy apply to this situation?

62
Convergence
  • Birds bats both have wings. Is this
    convergence?

63
Convergence
  • Birds bats both have wings.
  • Is this convergence?
  • Yes
  • evolved wings independently
  • common ancestor did not have wings
  • wings of both taxa are modified forelimbs
  • How do the terms homology, analogy, derived,
    synapomorphy apply to this situation?

64
Birds elongation fusion of 3rd 4th
metacarpals plus 3rd digit provides support for
airfoil of feathers (primarily) .
Bats elongation of 2nd through 5th metacarpals
digits provides support for airfoil of skin.
65
Reduction Loss
  • usually refers to morphology
  • reduction in size or prominence of a feature or
    element
  • loss of a morphological element

66
Reduction Loss
  • Example In the major evolutionary transitions
    from one taxon to another (e.g., fish to
    amphibian, amphibian to reptile, reptile to
    mammal), reduction loss of skull elements is
    typical.
  • Humans have relatively simple skull jaw
    structure (i.e., few elements). This is an
    example of simplification in a highly derived
    taxon.

67
Complexity of Fish Skull
68
Comparison Fish vs. Amphibian
dorsal view
69
Comparison Ancestral Reptile vs. Snake
dorsal view
70
Comparison Ancestral Reptile vs. Bird
dorsal view
71
Comparison Ancestral Reptile vs. Mammal
dorsal view
72
Reversal
  • evolutionary return to a condition seen in an
    ancestor
  • secondarily derived
  • determined by analysis w/in a phylogenetic
    framework

73
Reversal
  • Example Some Great Apes (that includes you) are
    secondarily terrestrial.
  • Ancestral primates evolved from terrestrial
    forms, became arboreal, then secondarily evolved
    terrestriality (maybe due to disappearance of
    forests expansion of savannas).

74
Specialization
  • morphological, physiological, and/or behavioral
    modification for a specialized biological role
  • considered an adaptation if current biological
    role of characteristic is same as its original
    role when it evolved

75
Specialization
  • Example egg-eating snakes (Dasypeltis)
  • specialized behavioregg-eating
  • specialized ecologygorge/fast strategy matches
    seasonal availability of prey
  • specialized morphology
  • extra scale rows on throat
  • vertebral processes protrude into esophagus
  • few teeth (loss / reduction)
  • extra elongation of quadrate bones
  • others

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77
What Evolution Is Is Not
  • Evolution is not like a ladder. Evolution is
    like a tree.
  • The parts of an organism (i.e., its
    characteristics) can be ancestral or derived,
    depending on what other organisms it is being
    compared to.
  • An organism is the sum of its parts. Therefore,
    an organism is a composite of ancestral derived
    characteristics.
  • Avoid using the terms primitive advanced in
    reference to organisms or taxonomic groups.

78
Evolution is the unifying theme of biology.
Everything biological is its product.Everythin
g biological makes sense only in the light of
evolutionary theory.
79
Darwin Quotes
  • I have called this principle, by which each
    slight variation, if useful, is preserved, by the
    term of Natural Selection.
  • On the ordinary view of each species having been
    independently created, we gain no scientific
    explanation.
  • The universe we observe has precisely the
    properties we should expect if there is, at
    bottom, no design, no purpose, no evil, no good,
    nothing but blind, pitiless indifference.
  • What a book a devil's chaplain might write on
    the clumsy, wasteful, blundering, low, and
    horribly cruel work of nature!
  • --Charles Darwin
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