EVOLUTION

 EVOLUTION

Before diving into the explanation of evolution, it’s good to first get to know taxonomy.

A. TAXONOMY

a. Definition
Classification by giving names. The classification system starts from grouping general characteristics to specific ones.

b. History

Aristotle
Classified living beings into two major groups: animals and plants. Plants were further grouped into herbs, shrubs, and trees. Animals were divided into three groups: land, water, and air.

C. Linnaeus

• Known as the father of taxonomy for systematizing taxonomy.

• Developed the binomial nomenclature system:

  1. Contains only genus and species. Species describe specific characteristics or where it was found.

  2. Uses Latin, a dead language that no longer evolves.

  3. Easier to use because it contains only two words (previously names could have up to seven words).

  4. Example: Motacilla tragodytes L, 1758 means genus Motacilla, species tragodytes, named by Linnaeus in 1758 and already described.

  5. Names like Motacilla tragodytes (L, 1758) do not explicitly indicate that Linnaeus described the species.

  6. If only the genus is known (species not determined), add "sp" for animals (e.g., Felis sp.) and "spec" for plants (e.g., Magnifera spec.).

  7. If multiple species are suspected but only genus is known, add "spp" (e.g., Felis spp.).

  8. If the organism resembles a known species but is not exactly it, add "cf" (e.g., Magnifera cf. indica).

B. TAXONOMY IN FOSSILS

Many fossil names differ from their original names — is this a problem? It depends on which names are more widely used.

• Morphotaxa are taxonomies based only on morphology and are widely used for plants and microfossils, especially pollen (fine to coarse powder made of pollen grains, the male microgametophyte of seed plants producing male gametes). This causes fossil names to differ from plant names. Example: Spinizonacoliptes.

• Paleobotany: study of fossil plants, which differ depending on whether leaves, wood, or pollen are studied.

• Phytoliths: silica from plants, especially in dry environments, with varying shapes used for naming.

C. EVOLUTION

a. Definition
Changes in inherited characteristics within a population.

b. Development of Evolutionary Theories

• Anaximander

  The cosmos formed from chaos.
  Life arose from dead matter.
  Higher organisms evolved from lower (simple to complex).

• C. Linnaeus

  Creation theory: all creatures created simultaneously by the Creator.
  Current forms are the same as at creation.

• Cuvier

  Catastrophes wiped out all life at the end of each period.
  New life appeared different from previous life after each catastrophe.

• Buffon

  Current life may have arisen from other life forms.

• Eugene Darwin

  Animals now may have come from stars.

• Lamarck

  Simple animals first appeared from non-living matter.
  Progressed from simple to complex.
  Organs frequently used grow and develop perfectly.

• Charles Darwin

  Current organisms evolved gradually from previous ones.
  Struggle for existence requires competitive ability within or between organisms.

Evolution is influenced by three factors:

• Genetics

• Time

• Natural selection: favors those who adapt to geology and climate.

c. Types of Evolution

• Macroevolution:

  Large scale, over a long time (more than one generation).
  Seen in the fossil record.

• Microevolution:

  Small scale, over a short time.

d. Direction of Evolution

• Retrogressive: from complex to simpler forms.

• Progressive: from simple to more complex forms.

e. Evolution Pace

• Very slow, e.g., brachiopods.

• Moderate, e.g., horses.

• Very fast, e.g., mammal development from Mesozoic to Cenozoic.

f. Final Result of Evolution

• Divergent: one species evolves into many new species (e.g., mammals).

• Convergent: similarity between two organs or organisms from different ancestors (e.g., shark and dolphin).

g. Selection

• Morphological and physiological changes.

• Occurs within a population.

• Produces varied offspring.

• Inherited genetics.

h. Effects of Evolution

• Adaptation

• Coevolution-Cooperation (joint evolution)

• Speciation

• Extinction

i. Evolution Symptoms

• Shell growth.

• Growth in specific parts (e.g., teeth).

• Suture development (e.g., ammonites).

• Direction of shell coiling.

• Shapes of specific parts.