Chapter 15 Flashcards
evolution general definition
change within organisms over time, 2 types:
development
acclimation: response to changing environment conditions
specific (biological) definition
change in the genetic makeup of a population over time
according to this definition, populations evolve, individuals dont
pre darwin ideas (aristotle)
species dont change over time
natural order exists in the world and does not change
plato
all objects can be represented by ideal forms
variation between indivduals represents a deviation from the ideal form (so is not important)
jean lamarack
2 driving forces in evolution
1. linear force:
evolution towards increased complexity and perfection
this is driven by some internal force in all living things
2. lateral force: adaptation to local conditions
organisms have features that suit them to where and how they live
mechanims for adaptation is use an disuse of parts:
body part that develop in a certian way during an individual life are passed to its offspring
charles darwin
sailed around the world in the 1830s as a naturlist on the beagle
proposed a mechisms for evultion in 1830s
continued to develop collect evidence for evolution for 20 years
1858:
alfred wallace devlopment the same idea as darwin
the origin of species
published in 1859
darwin was influenced by two ideas
- uniformitarianism: world is under constant slow change
large changes can occur over long periods of time
essay on population (1798, thomas malthus)
human population grow faster than resource supplies
when populations are stable, individuals suffer fro lack or resources
darwins mechanims for evolution: theory of natural selection
observations:
1. all organisms can reproduce at an exponential rate
2. populations do not increase expontially
3. resources are limited
the ideas of malthus apply to natural population
conclusion 1:
there is a struggle for existence between organisms within a species
observations:
4. indivduals in populations vary in a number of traits
5. some varibility is inheritied
conclusion 2:
the ability to survive is related to variation in different traits
indivduals with traits that allow them to survive in particular situations pass these traits to their offpsring
conclusion 3:
over many generations populations evolve, adapting to their enviorment
populations of the same species, in different environments, will evolve into different species
conclusion 4:
applying the concept of uniformitarnisam:
all species have evolved from a common anscestral species
theory does not explain were new variation comes from
impact of darwins ideas
branching pattern of evolution- all living things envolved from a common ansestor
non-constancy of species
struggle for existance is dominant force in nature
importance of variation within species
importance of probability
random events:
1. new variation
2. presence of organism in particular enviornment
the success of an orgainsm is partly a random event