Introduction to Evolution

aristotle’s idea

• scale of nature

• like a ladder on every rung is a species

  • no concept of evolution, whatever rung you were on that where you stayed

  • static

carolus linneaus ideas

• natural philosopher

  • classified and described organisms

  • hierarchical classification system

  • binomial nomenclature (scientific name = genus name + species)

    • still in use

  • common name, kingdom, phylum, class, order, family, genus, species

hutton and lyell ideas

• hutton:

  • theory of gradualisms- rocks/world is changing before, now, and later (not static)

    • landforms by mechanisms that are currently operating in the world

    • what we are seeing now, is a result of these gradual changes

• lyell:

  • natural laws that operate now, have always been operating

    • refined huttons gradulism by uniformitarianism (maybe the world is always changing)

    • the laws that dictate how things change are now and always been operating and will continue to operate

    • they were both focused on how geological features changed over time though

Jean Baptiste lamarck ideas

• first to apply theory to living organism:

  • species evolve though inheritance of acquired characteristics (theory)

• a organism would change during its lifetime and pass down those changes to their offspring

  • Giraffe

    • short neck → stretches neck to reach leaves → modern-day giraffes have long necks

• proposed a mechanism for evolution (inheritable changes over time)

Darwin’s ideas of variation (observations)

• members of a population often vary greatly in their traits → variety

• many individuals → very different

darwins idea of overproduction (observations)

• every generation species has a capacity to produce more offspring than environment can support

• more offspring are produced that can survive - differential survival and reproduction

darwin’s ideas of differential reproductive success (inferences)

• those individuals with most favorable combination of characteristics

  • most likely to survive and reproduce

darwin’s ideas unequal ability to survive and reproduce (inferences(

• lead to accumulation of favorable traits in population over generations

  • more favorable → reproduce more

darwin’s idea of how species use resources

• thomas mattus provided that: natural resources are limited

• organisms must compete with each other for the resources

• since there are more individuals than resources, some individuals do not survive

• there are other limits of population growth (why are there so few rabbits)

the mechanism of evolution

natural selection

“survival of the fittest” meaning in natural selection

the fittest are the ones with the most offspring

what does fitness mean

the organisms ability to reproduce and pass on traits

what occurs over the time as a result of natural selection?

evolution of the population and increase in favorable traits

sequence what happens when natural selection occurs due to environmental change

environment changes → organisms with favorable traits survive better → frequency of favorable traits increase → less favorable traits become scarce

what does natural selection do?

natural selection edits traits already in the population

what is the difference between individuals and populations in evolution?

population evolve, not individuals

what can results in the formation of a new species?

adaption over time due to natural selection

what is artificial selection

selective breeding by humans to pass on desirable traits

what’s the key concept of artificial selection?

specific traits are chosen and passed on, making them more common in the population and increasing the fitness of those individuals

whats an example of artifical selection?

agriculture - humans breeding crops or animals for specific traits

what is the direct observation as evidence of natural selection?

observing changes in species in response to environmental changes or introduced species

what’s a key concept of direct observation

natural selection edits existing alleles; organisms may not move into new environments and adapt

what are some examples of direct observation

• antibiotic resistance

• soapberry bugs evolving shorter beaks when fruit changed

what is homology?

similarity due to common ancestry

what is homologous structure

structures that look similar but have different functions, showing shared ancestry

what’s an example of homology?

limbs of humans, whales, sharks, and birds

what does the fossil record show?

evidence of ancient life through remains/traits preserved in sedimentary rock layers

what’s the key concept of the fossil record as evidence

fossils show when/where organisms lived and help infer lines of descent w

what’s an example from the fossil record

sedimentary rock layers, with each layer representing a different time period