Animal Development and Evolution

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Author:
MeanEddieG
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82052
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Animal Development and Evolution
Updated:
2011-04-26 20:46:06
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Mark Smith
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Bio 101
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  1. Principles of Animal Development


    Fertilization

    Sperm - head with acrosomal cap, midpiece, tail / Live 4-5 days
    Egg - surrounded by extracellular matrix called the Zona Pellucida and Follicle Cells called the Corona Radiata
    Fertilization

    Sperm Cell membrane fuses with egg cell membrane
    Egg nucleus and sperm nucleus unite - Zygote
  2. Stages of Animal Development


    Zygote
    Early Cleavage Stages

    Morula
    Blastula

    Gastrulation

    Gastrula

    Neurulation
    Organogenisis
  3. Cleavage - First mitotic divisions in a multicellular Zygote

    Cell Divisions without growth in size
    Continues until the Morula Stage



    -Cleavage Stages
    Morula Stage
    Solid Balls of Cells

    -Blastula Stage
    Forms a hollow ball of cells with a fluid cavity (Blastocoel)
  4. Gastrulation - invagination of cells into the Blastocoel

    Form distant cell layers - ”Germ” layers
    Pore Created - Blastopore
    Cavity is called Archenteron - primitive gut / Inside of our digestive system

    Early Gastrula - 2 tissue layers form

    Ectoderm - outer layer of cells

    Outer Body Tissues
    Nervous System skin, teeth, eye and nails

    Endoderm - Inner layer of cells

    Inner body Tissues
    Digestive systems and Glands

    Late Gastrula - 3rd Tissue layer form

    A middle Mesoderm layer is formed

    Middle Body Tissues
    Muscular/skeleton system and Cardio/respiratory/reproductive systems
  5. Neurulation - Formation of the nervous system from the Ectoderm

    Neural Folds form moving upward and joining to form a Neural Tube

    Becomes the Brain and Spinal Cord
  6. Organogenesis - Formation of the Organs

    Common Traits in Vertebrates

    Dorsal Neural Tube
    Notochord
    Pharyngeal gill pouches / Cause they look like gills
    Postanal Tail
  7. Human Embryonic and Fetal development

    Overview

    Human Development divided into 2 phases

    Embryonic Phase - months 1-2
    Fetal Development - months 3-9
  8. Embryonic development - development of all organ systems

    Week 1
    Fertilization occurs within the 1/3 of the oviduct
    Zygote undergoes the first cleavage divisions as it migrates through the oviduct toward the uterus
    After about 3 days it is in the Morula stage
    7 days to implantation
    Week 2

    Implantation occurs
    Gastrulation occurs

    Week 3

    Organogenesis begins

    Nervous systems develop
    Cardiovascular development begins


    Weeks 6-8

    Becomes recognizable as human form
    All organ systems are now established
  9. Fetal Development - refinement of these systems

    The Fetal period extends from the 3rd through 9th month
    The 3rd and 4th months

    Ossification of the skeleton begins / Hardening of the Bones
    Sex of the individual may be determined
    can hear the heartbeat during the 4th month


    Enlargement of the Body systems and Fetus occurs until the 9th month (Birth)
    Around the 8th month - Fetus sleeps 90-95% of the day, experiences REM Sleep, an indication of Dreaming
  10. Birth

    Contractions occur throughout pregnancy
    Stage 1

    Cervix begins to dilate
    Water Breaks - Amnion ruptured pressure of baby’s head wedged into the Cervix
    Stage 1 ends when the Cervix is fully dilated (10cm)
  11. Stage 2

    Contractions are 1-2 minutes apart and last about 1 minute
    Urge to Push
    Baby “Crowns”
    Baby Emerges
  12. Stage 3

    Delivery of the Placenta
    Occurs after the Birth of the Baby
  13. Extraembryonic membranes

    In Humans

    Chorion develops into the fetal side of the Placenta

    Gas and waste product exchange with maternal circulation

    Allantois vessels become the umbilical vessels
    Amnion contains the amniotic fluid / Has to break to start labor
    Yolk Sac is the earliest site of blood cell formation
  14. What was the thought before Darwin???


    Lamarck (1801) - Came up with the idea of Inheritance of Acquired Characteristics
    Which Says: The Subconscious ‘desires’ of an organism can cause changes in the traits of that organism
    And those changes caused by increased use or disuse will be passed onto the offspring of that individual
  15. Darwin

    Studied medicine and Theology
    was the naturalist on a 5 year voyage on the HMS Beagle. 1831
    Wrote “The Origin of Species” 1859.
  16. Darwin and Wallace

    While Darwin was researching at his home he received a letter from Alfred Wallace
    A young naturalist collecting organisms in South America
    This letter was asking advice about an idea Wallace had been working on (Same as Darwin)
    So we give Darwin the credit cause he did the most of the work and research (they authored together)
  17. Evolution

    Defined: Genetic change in Organisms over time through reproduction.


    Main Points of Evolution

    Populations evolve not individuals
    Evolution mainly occurs through Natural Selection
    Evolution is the main unifying theme of all biology

    Example: Pepper Moth
    Horse Evolution
  18. Natural Selection

    Variations in form of behavior between members of a species
    These variations are inheritable from one generation to the next
    There is competition between individuals of a population or species
    Those individuals with the adaptable traits will be more likely to reproduce (differential reproduction success) and pass those adaptive traits on with greater frequency to future generations
  19. Evidence of Evolution

    Fossil Record
    Artificial selection
    Evolution in Action
    Comparative Anatomy
    Comparative Embryology
    BioChemistry and DNA
    Biogeography
  20. Fossil Record

    Evidence of past living organisms

    What do they tell us?

    Past organisms are different from todays living ones
    Fossil layers show a trend in evolution from simple to more complex (generally)
    Intermediate fossil are being found now.
  21. Artificial Selection

    Shows that change can occur and the environment can cause it
    Many examples from our domestication of plants and animals
  22. Evolution in action

    Pesticide resistance in insects
    Bacterial and Viral resistance to Medicine
  23. Comparative Anatomy

    comparing the structure of organisms to see if the individuals are related or not

    3 Types of Structures

    Homologous - Structures that have the same framework (Internal Structure)
    Analogous - Structures that dont have the same framework
    Vestigial - Structures that have no apparent use in the present owner but are used in related organisms
  24. Similar Vertebrates Embryos

    Genes past through common ancestry
  25. Biochemistry and DNA

    Shows which Organisms are related to each other
    How???
    DNA and its gene sequence comparison between Humans and Chimps
    Red Panda and Giant Panda = Panda is a Bear
  26. BioGeography

    What is it??? Study of life on the planet / Marsupials are in Australia because they are isolated by Geography the placental animals survuved better as the land was notr separated as they better adapted before the split.
    Example: large flightless birds descended from a common ancestor, regardless of were they live.
    Also deals with Plate Tectonics and Continental Drift. Comes from Geology
  27. Continental Drift

    Idea that the continents were once joined and have since drifted apart. (moves 1-2 inches a year)
    Due to plate tectonics
  28. Plate Tectonics

    Earths crust is fractured into plates
    Movement of Plates is driven by upwelling of molten Rock at mid-oceanic ridges
    As seafloor spreads, older rock is forced down into trenches
  29. Summary of Darwin’s Theory

    Individuals in nature differ from one another
    Organisms in nature produce more offspring that can survuve, and many of those who do not reproduce
    Because more organisms are produced than can survive, each species must struggle for resources
    Each Organism is unique, each has advantages and disadvantages in the struggle for existence
    Individuals best suited for the environment survive and reproduce most successful
    Species change over time (to survive)
  30. MicroEvolution

    Small scale genetic changes in populations
    Causes of Microevolution

    Mutation
    Gene Flow
    Genetic Drift
    Natural Selection
  31. Mutations - Changes ini the DNA that are passed onto the Offspring
    (1in a million gametes a mutation occurs)

    Types of Mutations

    Lethal Mutation
    Adaptive Mutation
    Neutral Mutation (most common occurring mutation)
  32. Gene Flow - The exchange of genes between populations

    Making populations similar in traits and genetics
  33. Genetic Drift - The random genetic changes in a population

    Sub Types -

    Founder Effects -

    When a small group of individuals colonize a new habitat and thrive, becoming a new population (Common on Islands)

    Bottleneck Effects -

    When there is a sever reduction in population size, the resulting population will have less genetic variation and more similar traits (Cheetahs have gone thru 2 Bottleneck effects/They are too similar; sterile)
  34. Natural Selection -

    Types of Natural Selection

    Stabilizing Selection

    Intermediate forms are favored and extremes are eliminated

    Directional Selection

    Allele frequencies shift in one direction (Pepper Moth Example)

    Disruptive Selection

    Allele frequencies shift in two directions!
  35. Special Population Selection Models

    Sexual Selection - When one form or sex chooses its mate based on fitness of that individual. (Chooses the best mate)

    Causes a huge amount of genetic change within 1 generation of a population.
    Requires Sexual Dimorphism

    a species with 2 forms of sex

    Occurs only during the mating season
  36. Genetic (balanced) polymorphism - When there are two forms of a trait that are maintained within a population year after year

    Example -
    Sickle Cell Trait: Heterozygote Advantage

    Sickle Cell is more resistant to Malaria, so it stays around because of the advantage to the population of people who live in Africa (Can only have this through Genetics) Get Malaria from the Female Mosquito only
  37. Macroevolution

    Large Scale genetic change or evolution
    Development of new species

    What is a species - A group of interbreeding individuals that are reproductively isolated form other such groups (Genetically Distinct) (Cant Breed Together)
  38. Reproductive isolation

    A PreZygotic isolation (Before Sperm and Egg Meet)

    Behavioral R.I. - The mating behavior between species keep them from reproducing (King Cobra - mating behaviors - sniff,touch tongues, dance the other and snakes have to rub up against each other to excite to mate 4 ft off the ground)
    Ecological R.I. - They live in different habitats
    Temporal R.I. - The mating seasons are different
    Mechanical R.I. - The reproductive parts don’t fit
    Gametic R.I. - The sperm does not survive in the females environment
  39. PostZygotic Isolation

    Zygotic R.I. The embryo dies before birth
    Hybrid inviability - The offspring does not survive well and dies before reproductive age
    Hybrid Sterility - The offspring is sterile and can’t pass on the new genetics (Like a Mule - Female Horse and a Male Donkey can only produce this)
  40. Hybrids (Horse and Zebra)

    Zorses! (It can produce on its own / New Species) Wacky things happen on Farms changes the mating rituals of each species
  41. Speciation & Natural Selection

    Natural Selection can lead to speciation
    Speciation - can also occur as a result of other microevolutionary processes

    Genetic Drift
    Mutation
    Etc...
  42. Speciation Models

    Allopatric Speciation - The development of new species by a physical separation from the original species (Oceans, Mountains, etc.)
  43. Sympatric Speciation - The development of a new species within the same environment as the original species
  44. Rates of Speciation

    Gradualism - at a slow and gradual rate
    Punctuated Equilibrium - The development of new species in a short amount of time, then those species remain the same

    (SubType - Adaptive Radiation) - is the new development of ALOT of new species at one time. (Has happened 7 times on the planet, always after 85% extinction of organisms)
  45. Extinctions

    3 types

    Local Extinctions - a part of species in a specific area
    Species Extinction - Entire Species is Gone forever (Cheetahs are next for Example)
    Mass Extinctions

    have played a major role in evolutionary history (Are in the middle of the 7th now) The 6th one was the (Ice Age)

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