Evolutionary biologists and evidences for evolution

Aristotle

• steps of nature

• first classification of nature

• lifeless objects to animals

• no evolution → made by god

Linnaeus

• Binomial nomenclature

• hierarchical classification hinted at evolution

• system for naming species, using two Latin names for each organism, genus and species.

• uses physical characteristics

• racist

Erasmus Darwin

• grandfather to C. Darwin

• talked about evolution → all changes are a natural process → all life came from 1 ancestor (“one single filament”)

• studied how animals had different beaks + different colors depending on how it blends in

Lamark

• theory of lamarkian evolution

  • tendency for life to be more complex over time

  • organisms are spontaneously generated

• USE AND DISUSE:

  • characteristics strengthen and weaken with use and disuse

  • can pass these “strengthened/weakened” characteristics to new generation (i.e. giraffes stretching their necks)

• traits that are used more become more common

G. Cuvier

• paleontology

• classification based on anatomy

• catastrophism theory that species extinction occurs due to sudden, catastrophic events rather than gradual evolution.

• known for establishing the fields of paleontology and comparative anatomy

• he argued against the idea of evolution, believing instead that species were fixed and unchanging.

James Hutton

• timeframe was necessary for evolution

• earth was a lot older than previously thought

Natural selection:

• organisms changed over time & adapted to its environment → best adaptations would survive and others would perish

• set scene for C. Darwin

• gradualism

Charles Lyell

• influenced Darwin

• geological changes are slow, constant, steady

• Uniformitarianism

• species gradually emerged from other species (evolution)

Thomas Malthus

• produce far more offspring than can survive

• population growth

Wallace:

proposed wallace line: created by drawing circles around places where land animals are found and observing the barrier

• certain relatively close islands/continents had vastly different species (asian vs australian), while other close islands had similar ones.

• plate tectonics and glaciation

C. Darwin

• proved that evolution comes from natural selection

  • species adapt to their environments, give rise to sub-species that survive better

• 20 years of experimenting with an artificial selection pigeons to gather evidence for evolution by natural seletion

• His work led to the formulation of the theory of evolution, emphasizing survival of the fittest.

  • Experimentation:

    • birds had distinct beak shapes and sizes for different food (hard seeds = strong thick beak, insects = slender pointed beak)

• fossils

Artificial selection

• breeding specific traits together

  • people (instead of nature) determine which organisms reproduce

  • control certain phenotypes and traits

Embryology

• embryo’s in their late stage show unexpected links in organisms → look the same as well → fish reptiles, birds, and humans all have gill slits during their embryonic stage, indicating that they come from the same/similar origin species

Biostratigraphy

• younger rocks overlay olderrocks

• relative dating of fossils

  • deeper the fossil is, the older it is

    • located transitional forms of organisms and organism distributions

Paleontology

• fossil evidence shows life is old + changes over time

  • compare old fossils with similar younger ones → discover more anatomical similarities and changes

Vestigial Structures

• non-functional byproduct of an organisms’ biological/evolutionary history

  • structure might have been useful for ancestors, but due to environmental change, structure is useless. Generations of disuse will cause it to be useless + require as little energy as possible

    • there are also insufficient negative effects to REMOVE it from the organism (also requires energy to remove it)

    • i.e. some aquatic organisms that live in caves lose their vision but still have eyes, or how 5 fingers are in a whales fin.

Transitional Forms

• organisms that show the intermediate forms between an ancestral form and its descendants

Biogeography

• how species are scattered around the world through plate tectonics, glacier shifts, and migration

  • i.e. wallace line

Homologous Structures

• structures/traits inherited from a common ancestor.

  • may or may not have the same function

  • parts may be lost/fused during evolution

  • share similar anatomical structures reflecting common ancestry despite differences in functions

Analogous Structures

• organisms have similar issues to solve → different structures meant for same purpose

  • originated independently from diff lineages and organisms

  • i.e. bird wings and bat wings

Molecular Biology

Different proteins are more important to one organism than others, so they differ in their susceptibility to changes in the DNA

• organisms have different needs → different protein synthesis/usage DNA

Molecular Genetics

• trace common DNA sequences

  • longer the separation of species, more changes