Animal%20Architecture%20and%20Taxonomy

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Animal Architectureand Taxonomy

• Chapters 9 and 10

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Hierarchy of Organization

• Protoplasmic
• Single celled life - Protists
• Cellular
• Cells carry out different functions - Sponges
• Tissue
• Cell unite into tissues that perform functions -
  jellyfish
• Organ
• Different tissues united to form organs -
  flatworms
• Organ system
• Organs united to form complex systems
  earthworms and up

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Size does matter

• Animals (Metazoans multicellular animals) are
  capable of using different body plans, but this
  is determined in part by size.
• As size increases, the surface area (SA)
  increases at a different rate that body volume
  (V)
• SA body length2, while V body length3
• SA is required for cellular respiration, the
  moving of nutrients into cells, and the removal
  of waste.
• As SA increases, greater degrees of organization
  are required to get nutrients into cells (food,
  O2,water) and to remove wastes (biproducts, CO2,
  etc.) This has led to the development of
  tissues, organs, and organ systems.

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Advantage of size

• Larger body size does provide several advantages,
  and is worth this extra organization.
• It is a buffer against the environment (heat,
  cold)
• It allows more opinions in protection from
  predators
• More efficient metabolic costs
• A large mammal uses more O2 in thermoregulation,
  but use less per gram than a small mammal.
• A large mammal uses more O2 to move than a small
  mammal, but uses less per gram to move over the
  same distance.

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Extracellular Components

• Fluids in metazoans exist in 2 regions
• Intracellular fluids
• Fluid within cells
• Extracellular fluids
• Fluid between cells
• Extracellular fluids can be further divided in
  animals with closed vascular systems into
• Blood plasma fluid that suspends blood cells
• Interstitial fluid (tissue fluid) fluid
  surrounding cell and tissues
• Extracellular structural elements
• Loose connective tissue
• Cartilage
• Bone
• Cuticle

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Types of Tissues

• Tissue a group of similar cells specialized to
  perform a common function.
• Histology the study of tissues
• There are four basic tissue types
• Epithelial
• Connective
• Muscular
• Nervous

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Epithelial tissue

• A sheet of cells that covers an external or
  internal surface.
• Used for protection of structures, as well as
  producers of lubrication (mucus) or other
  produces (hormones and enzymes).
• Divided into different types of simple and
  stratified epithelia.

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Connective Tissue

• Generally made of a few cells suspended in a
  fluid (matrix and extracellular fibers.
• Two main types
• Loose connective tissue
• Fibers and cells suspended in a syrupy matrix
  like adipose (fat) tissue
• Dense connective tissue
• Densely packed fibers , as in collagen

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Connective Tissue

• Other types of specialized connective tissues.
• Blood, lymph, and tissue fluid
• Specialized cells in a watery matrix
• Cartilage
• Semirigid of closely packed fibers in a gel
  matrix
• Bone
• Calcified tissue with calcium salts organized
  around collagen fibers

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Muscle Tissue

• Most common tissue in animals
• Made of muscle fibers designed for contraction
• Divided into striated (striped) muscle
• Skeletal
• Cardiac
• And visceral (smooth muscle)
• Smooth muscle

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Nervous Tissue

• Specialized for reception of stimuli and
  conduction of impulses from one region to
  another.
• Neurons
• Basic functional nerve cell
• Neuroglia
• Nonnervous cells that insulate neuron membranes

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Animal Body Plans

• Major evolutionary advancements include
• Multicellularity
• Bilateral symmetry
• Tube-within-a tube
• Eucoelomate (true Coelom)

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Symmetry

• Symmetry refers to balance or equal opposite part
  across a medium plane.
• Spherical symmetry
• Any plane passing thru through the center creates
  equal mirror opposites seen in protozoans
• Radial symmetry
• Can be divided into similar halves along more
  than 2 axis
• Typical among the Radiata (hydra and jellyfish)
  along with sea urchins and starfish
• Bilateral symmetry
• Can only be divided into two equal halves along a
  sagittal plane.
• Allows directional movement, and help lead toward
  cephalization

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Evolution of the Body Cavity

• Development of a coelom
• A fluid-filled cavity between the outer body wall
  and the gut
• Allows greater body flexability and design
• Provides space for internal organs
• Creates additional surfaces for cellular
  reactions
• In some animals, functions as a hydrostatic
  skeleton (earthworms)

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Types of Coelom

• Acoelomate
• Lacking a true body cavity.
• Space is filled with mesodermal tissue called
  parenchyma.
• Ex. flatworms

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Types of Coelom

• Pseudocoelomate
• Have a tube-in-a-tube system, but tube is not
  derived from the embryonic mesoderm
• Cavity lacks a peritoneum

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Types of Coelom

• Eucoelomate
• Possess a true coelom derived from mesodermal
  peritoneum
• Formed in 2 ways, although results are identical
• Schizocoelous
• Splits form within the mesoderm
• Enterocoelous
• Form from pouches of the primative gut

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Metamerism

• Also called segmentation
• The serial repetition of similar body segments
  along an axis.
• Each segment called a metamere, or somite
• Found in many animals, but true metamerism is
  found only in the Annelids, Arthropods, and
  Chordates.

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Cephalization

• The differentiation of a head end of an animal
• A site of concentrated nervous tissue and sense
  organs.
• Provides a benefit to an animal moving forward
  (headfirst) through the environment.
• Also accompanied by polarity, or the
  differentiation between the anterior and
  posterior halves of the body.
• Ex. Legs are used for locomotion, while arms are
  used for carrying and manipulating objects

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Taxonomy and Classification
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Taxonomy vs. Systematics

• Taxonomy is the science of naming and classifying
  organisms.
• Systematics is the science determining the
  evolutionary relationships between organisms.

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Carl Linnaeus (1707-1778)
Systema Naturae And Binomial nomenclature
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Binomial System of Nomenclature

• All described species have an official name
• Species name genus specific epithet
• Genus is capitalized
• Specific epithet is not capitalized
• Name is written in italics or underlined
• Example Homo sapiens or Homo sapiens

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Hierarchical Classification
Seven required ranks

• King Kingdom Animalia
• Philip Phylum Chordata
• Came Class Mammalia
• Over Order Primates
• For Family Hominidae
• Good Genus Homo
• Steak Species sapiens

There are up to 23 other ranks that can optional
be used (Superorder, Subclass, Tribe, etc.)
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Phylogenies

• The best classifications should reflect
  evolution.
• A phylogeny is an evolutionary tree and should be
  a hypothesis on the evolutionary pathways and
  relationships of the organisms they depict.

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Phylogenies

• Phylogenies are built based on shared characters
• A homology is a character derived from a common
  ancestor
• Example - the bones in a bat wing are homologous
  to the bones in a human hand
• A homoplasy is a character that looks similar in
  two organisms, but derived from different
  structures ancestorally.
• Example Tree Pythons and Tree Boas look
  similar, but come from different ancestors.

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Terms in Phylogeny

• Ancestral character state a character possess
  by the most recent common ancestor
• Derived character state a character different
  from the ancestral state, presumably evolved
• Outgroup an organism used in polarizing a
  phylogeny so to determine character states
• Synapomorphy a shared derived character state
• Clade a groups that share synapomorphies

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A phylogeny
Nested clades
Primitive chordate
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Sources of Phylogenetic information

• Comparative morphology
• Examining the differences in shapes and sizes of
  structures. Useful for living and fossil
  organisms.
• Comparative biochemistry
• Examine differences in amino acid and DNA
  sequences between organisms. Mainly done on
  living organisms, but some fossil contain enough
  DNA to still work.
• Comparative cytology
• Compare the numbers, shapes, and sizes of
  chromosomes. Used solely on living organisms.

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A phylogenetic tree

• A phylogenetic tree is different from a
  cladogram, in the lengths of the arms indicate
  degrees of difference.
• This tree is created based off of different s
  of mutations in the cytochrome B gene.

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Taxonomic Groupings

• Monophyly contains the most recent common
  ancestor and all its descendants.
• Paraphyly contains the most recent common
  ancestor and most, but not all, its descendants.
• Polyphyly does not contain a recent common
  ancestor, therefore coming from two lineages.

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Systematics

• Traditional Systematics based off of adaptive
  zones by George Gaylord Simpson. Basically
  states that the more similair an organism is to
  another, the more closely related it probably is.
• Phenetic taxonomy a method of mathematically
  calculating relatedness based on similarity.
  Largely discontinued today.
• Phylogenetic systematics (Cladistics) stresses
  formation of clades on monophyletic groups
  containing synapomorphies uniting them.

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Cladistics

• Developed in 1950 by Willi Hennig
• Argued against paraphyletic groups, since they
  were unnatural.
• Current work in phylogentic systematics is
  directed toward revising taxonomy within the
  Linnean system.

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What is a species?

• Typological Species Concept
• Biological Species Concept
• Evolutionary and Phylogenetic Species Concepts
  (Cladistics)

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Typological Species Concept

• What an expert says that a species is.
• Earlier it was thought that God created a perfect
  creature, and most of the present organisms were
  poor representatives of the ideal, or true
  type.
• Based on morphology.

The real type of Homo sapiens?
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Biological Species Concept

• A species is a reproductive community of
  populations (reproductively isolated from others)
  that occupies a specific niche in nature.
• Emphasis is on reproductive isolation.
• A testable definition in many cases.

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Problems with the Biological Species Concept

• Asexual organisms?
• What do you do with fossils?
• Some species are readily genetically compatible,
  such as orchids.
• Some species readily hybridize.
• Ring species are an example of the difficulty in
  the BSC.

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Evolutionary Species Concepts

• A single lineage of ancestor descendant
  populations that maintains its identity from
  other such lineages and that has its own
  evolutionary tendencies and fate.
• Takes into account that species are from a
  lineage of individuals with a unique past and
  future.
• Includes fossils and asexual organisms, but any
  easier in practice?

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Phylogentic Species Concept

• An irreducible (basal) grouping of organisms
  diagnosably distinct from other such groupings
  and within which there is a parental pattern of
  ancestry and descent.
• Focus on common descent and monophyletic
  groupings.
• Tends to result in the greatest number of
  distinguishable species.

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Phylogeny of Life

• 3 major divisions
• Bacteria - true bacteria
• Archaea - prokaryotes differing from bacteria in
  membrane structure
• Eucarya - eukaryotes

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Classical (Read Old Fashion) Classification of
Kingdoms
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Tree of Life http//www.tolweb.org
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Eucarya

• Microsporidia
• Flagellates
• Ciliates
• Fungi
• Plants
• Animals

Protozoan groups