Microevolution– Genetic changes in populations over time because of natural selection, genetic drift, gene flow (between populations), bottlenecks, and mutations

Macroevolution– Evolutionary change above species level. This is the origin of new species and higher taxa

Modes of speciation are distinguished by the mechanism interrupting gene flow within populations:

  • Allopatric Speciation– Geological processes can fragment a population into two or more isolated populations Ex. Mountain ranges, glaciers,colonization of new islands

What causes evolutionary change above the species level? Origins of new species and higher taxa?

——The sudden origin of wholly new types of organisms that occur through

-Transgenic Events: the lateral transfer of genetic material from one species to another with 2 mechanisms: Transposable elements (jumping gene) and Symbiogenesis

–> Transposable elements are specialized DNA segments that move (transpose) from one location to another

  1. Within a cells DNA
  2. Between individuals
  3. Between species

-Changes in Homeobox genes: Macroevolutionary events were strongly influenced by changes in this gene

Symbiogenesis

-Responsible for the origin of the Eukaryotic cell

-Could give rise to different kingdoms,groups, phyla

******The combination processes of anagenesis (microevolution) and cladogenesis (macroevolution) have given rise to the incredible diversity of organisms

Animal Architecture and Dev.

All animals have to accomplish the same physiological tasks to survive and repo. Organisms body evolved differently to preform these tasks

  • Ingestion, Digestion, Metabolism, Circulation, Respiration, Excretion, Repro.

Main criteria in which animals have traditionally been classified:

  1. Symmetry
  2. Tissue Layers
  3. Body Cavities
  4. Patterns of dev

Screen Shot 2017-08-30 at 10.51.09 AM.png

Caphalization=formation of a head (concentration of nervous, sensory tissues at the anterior end)

Tissue Layers

Germ Layers–  Embryonic tissue layers, group of cells that behave as a unit during early stages of embyronic dev. gives rise to different tissues/organ systems in the adult

Ectoderm- Outer layer (forms the outer epithelium, nervous system)

Endoderm- Inner layer (Forms the gut lining and its derivatives)

Mesoderm- Middle layer (Muscle etc.)

Diploblastic animals- 2 layers only (ecto and endo)

Triplobastic animals- 3 layers (ecto, meso, endo)

Body Cavities:

Screen Shot 2017-08-30 at 11.15.38 AM.png

-The coelom likely evolved in the common ancestor of protostomes and deuterostimes

-Bilaterians with a coelom completely lined in mesoderm are called coelomates

-Bilaterians that subsequently lost their coelom are called coelomates

-Bilaterians that retain a coelom but lost the mesodermmal lining in parts of the coelom are called pseudocoelomates

—> The coelom creates a fluid-filled container for circulation of 02 and nutrients, and acts as a efficient hydrostatic skeleton

Screen Shot 2017-08-30 at 11.29.49 AM.png

Two major groups of coelomate animals protostomes and deuterostomes

-They differ in: the fate of the blastopore that forms during gastrulation and Coelom formation

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