Ideas of origins (Theories) Flashcards
origin of the ideas of origins
pre 1700 (6000 yr old earth organisms unchanged)
lamarck with first fully formed theory
disproved by mendel
charles darwin
gould/ eldredge with punctuated equilibrium
what did Lamarckism propose
species changed over time and there is an inheritance of acquired characteristics as organisms adapt
state the two laws of Lamarckism
law of use and disuse- organism adapt to the environment and use a particular characteristic more, proposes that it will become bigger in size and efficiency whereas less used becomes smaller and disappears
law of inheritance of acquired characteristics- physical acquired phenotypic changes in parents will be passed on to offspring and populations change
why is Lamarckism rejected?
environment does result in phenotypic changes but Mendel proved that changes in phenotype (somatic cells) do not effect the genotype and gametes and hence cannot be passed on in egg and sperm to new organisms
change is rather due to variation (meiosis, mutations and chance fertilization)
How did Darwinism come about
HMS beagle to Galapagos islands to see finches with different beaks in different areas with different food source- wrote book called origin of species through natural selection
What were Darwin’s observations? (4)
more organisms reproduces yet environment stable
variation creates unique offspring
environment changes result in differential reproduction and organisms adapted to environment reproduced
characteristics are heritable from parents to offspring
Define Natural selection
Individuals with the physical, behavioral or other characteristics that are well suited to the environment are more likely to survive and reproduce than those that are less suited
Evolution by natural selection ? (7)
organisms will produce large number of offspring
great deal of variation among offspring
environment change/ competition
organisms with favorable characteristic to that environment will survive and organisms with unfavorable will die out
organisms with favorable characteristics will reproduce resulting in alleles with favorable characteristics passed on to next generation
next generation will have higher proportion of organisms with favorable allele
eventually all individuals will have favorable characteristic and natural selection will occur resulting in new species
Is natural selection perfect and random?
not perfect as environment constantly changes
not random as it is dependent on favorable characteristics but variation is random
Who came up with punctuated equilibrium
gould and eldrege
define punctuated equilibrium and what can be used to prove it
refers to the speed at which evolution takes place
fossils- long period of unchanged organisms
short period of rapid change (lack of transitional fossils)
explain punctuated equilibrium (3)
Organisms are unchanged for long periods of time (equilibrium)
Rapid change occurs over a short period of time due to environmental change (natural selection
new species with favorable characteristics formed
