lecture 18- descent with modification Flashcards
what does natural selection result in
adaptive evolution
accumulation of inherited characteristics that increase the ability of an organism to survive and reproduce in its environment
what are the layers in sedimentary rocks called
strata
how do fossils help understand evolution
show the organisms that lived throughout time
what is the concept of catastrophism
boundaries between strata were due to catastrophes (floods, droughts) which destroyed the living species and process repeats
what was lamarck theory of evolution
organisms pass traits to offsprings through use and disuse (parts of body not used deteriorate and go away)
giraffes neck grew cuz the animal stretched it to get high leaves
organisms would get perfect over time
what is gradualism and who proposed it
profound change can happen through the cumulative effect of continuous processes
hutton
what did darwin base his theory on
malthus’ essay: struggle for existence
lyell’s principle of geology
principles of artificial selection
own data (galapagos islands)
what was “struggle for existence” about
population growth is not always desirable
limited resources will break the growth
what are the principles of geology
changes to the earth’s surface come from slow continuous actions that are still operating today
what is artificial selection
plants and animals being breeded by humans to get desired traits
large changes over short period of time
what did darwin hypothesize about mainland and island animals
he said that the mainland animals colonized the islands and then diversified depending on the habitat of the different islands
how do population sizes stay stable
the resources are limited: struggle for existence/competition so few offsprings survive
how does the genome of a population change
organisms with favourable traits have more chances of reproducing: more offsprings who will also pass down those traits by surviving: favourable characteristics accumulate over generations
do individuals evolve?
no only populations can evolve
what does evolution depend on
the environment in which the organism is in
what are the pieces of evidence that support darwin’s theory
natural selection in action
homology
convergent evolution
biogeography
fossils
what is homology and what are the types
similarities resulting from a common ancestor
anatomy, development and molecular
what are homologous structures
anatomical resemblances that demonstrate a common ancestor but that have different functions in different organisms
what is divergent evolution
different environments which made the same traits evolve into different things that have different functions
what are vestigial organs
organs or structures that are useless
leftovers from ancestors
what do vestigial organs indicate
organism has evolved from ancestors where organ was functional
there is no selective pressure to eliminate them
development homology
all vertebrate embryos have gill slits in throats at some point
develop into different structures
molecular homology
universal dna code, 3 nucleotides for a codon, some codons code for the same thing in many organisms
evidence of common ancestor
what is analogous convergent evolution
characteristics are similar but no common ancestor, evolved independently from different ancestors
