ch 22 Flashcards
(23 cards)
typological thinking
- Plato
- every organism is a perfect essence
- unchanging species
typological thinking + scale of nature
- Aristotle
- fixed species types organized into a sequence based on increasing complexity
- minerals and plants at bottom all the way to humans at top (superior)
- lower and higher species
change through time + scale of nature
- Lamarck
- species change over time via inheritance of acquired characteristics
- simple organisms develop first spontaneously (at base of scale)
- organisms evolve over time and move up scale, becoming larger more complex “better” species
- as an individual develops phenotype changes in response to environmental challenges which are then passed onto offspring
- ex: giraffes develop long necks as they stretch for trees, producing long-necked offspring
change through time + common ancestry
- Darwin and Wallace
- natural selection
- population thinking
population thinking
the importance of variation among individuals of a population (opposite of typological since they consider variation unimportant)
descent w modification
how species today are derived from past ancestors
extant species
alive today
evidence for evolution
1) how long it takes for rock formations to form–earth is very old–geologic time scale w fossils based on sedimentary rock layers, radioactive dating
2) extinction changes species present over time, species are not static then
3) transitional features link older and younger species–law of succession–old species have similarities to current ones
4) vestigial traits (reduced or no function but still present bc present in past ancestors)
5) species can be observed changing even today (ex: antibiotic resistance, galapagos finch beak change
evidence for common ancestor
1) similar species are found in the same geographic area, change over time to form species from original ancestor as with the finches
2) related species share homologies (which is why something like CRISPR-cas can work since dna is homologous and why other organisms can be used to figure out stuff with disease in humans)
3) formation of new species from preexisting species can be observed today
does natural selection change individuals
NO. only the population does. individuals do NOT adapt.
acclimatization (acclimation if in laboratory setting)
- change in individual’s phenotype that occurs in response to a change in natural environmental conditions
- NOT passed onto offspring bc alleles don’t change==>does NOT cause evolution
- ex: if in high altitude body produces more red blood cells or something
is evolution progressive?
NO. only suited for the environment. there are no “better” organisms–just better fit for their environment; traits aren’t always adaptive
fitness trade-off
- a compromise btwn two traits that cannot be optimized simultaneously
- ex: bright coloring to attract mates or hidden coloring to not be seen by predators
genetic correlation
when selection on one trait causes change in another
other processes of evolution
- genetic drift
- gene flow
- mutation
random processes that do not necessarily improve fitness^^^^
relative dating
comparing rock layers to estimate when fossil was from
absolute dating
exact dating using stuff like tree rings, radiometric dating, and paleomagnetic dating
how many species in all of earth’s history are extinct?
99%
law of succession
fossil species are strikingly similar to existing species in the same geographic areas
what is the most fundamental homology?
the genetic code
internal consistency
- Observation that data from independent
sources agree in supporting predictions made by a theory - Data from many different sources are much more consistent
with evolution than with special creation
“struggle for existence”
Many more individuals are born than can survive==>Thus, compete for resources
when does natural selection occur?
Heritable variation leads to
differential reproductive success
