Evolution Flashcards
Evolutionary theory
All life forms are fundamentally similar at a cellular and molecular level
Aristotle
All living things have been created in their present form (developed through strongly held religious beliefs
Buffon
Studied animal structures. considered thier functions, was puzzled by some features that seemd to have no purpose (pigs toes)
Evolutionary theory: Erasmus and Dawrin
Evolutionary theory
Proposed that life evolved over time
Cuvier
(paleontology)
found fossils of simple organisms in all depths, more complex fossils found in shallower deposits and
Catastrophism: global catastrophes such as floods, caused the widespread extensions of species. These species were then replaced by brand new species
Uniformitarianism - Lyell
lyell (geologist)
-Earth has been changed by the same process that occurs in the past that occurs now
-geological change is slow and gradual not fast
-natural laws that influence these changes are constant, they operated in the past with the same intensity as they do now
Evolutionary theory
(Lammark) proposed that evolutionary change resulted from 2 different principals: use and disuse and inheritance of acquired characteristics
Use and disuse: structures an individual uses become larger and stronger, while those not used become smaller and weaker
Inheritance of acquired traits: individuals can pass down characteristics they acquire during their life (flawed)
Darwin
Linked ideas from paleontology, geology, geography to natural selection
sailed on the HMS beagle
Finches: collected on galapagos, beaks modified to suit food source, descended from common mainland ancestor
Patterns in diversity
-species vary locally
-species vary globally
-species vary over time
Descent with modification
Darwin proposed that descendents of the earliest organisms spread into various habitats over millions of years
Survival of the fittest
Darwin -
the ability of an individual to survivae and reproduce in its enviornment
Homologous strucutres
Common evolutionary origin, not same function
ex. bird and bee wing
Analogous strucutres
Share similar function but not evolutionary history ex. human, whale, bat,
Vestigial structures
Non-functioning structures that are present in reduced form (important in past but not now)
ex. wisdom teeth, diet has changed, dont need three molars
Artifical selection & issues
Breed animals for particular traits
issues:
-traits for desire rather than purpose (medical issues)
-playing “god” with unknown ripple effects
-decrease genetic diversity
-create monocultures that can be wiped out easily
Hardy weinberg equilibrium
Populations not undergoing change do not evolve, HWE quantifies genes by MEASURING ALLELE FREQUENCY
provides a BASELINE that makes it possible to recognize when a gene pool is changing
5 constant conditions for HWE
-population is very large
-there is no random mating
-no mutations occur
-no migration occur (gene flow)
-no natrual sellection occurs
Microevolution
Gene pool frequences of alles change within a population(evolution on a small scale)
Genetic drift
Changes to allele frequency by chance uncontrolled) in small populations
-bottle neck effect: dramatically reduces population and gene pool due to natrual disaster, only certain alleles are represented
-founder effect: individuals leaving a population establish a new one
Gene flow
a random process involving exchange (migration) of fertile genes with another population
Types of microevoution
-stablizing selection *
-directional selection *
-disruptive selection *
-sexual selection
-culmative selection
-altruism
Stabilizing selection
average phenotype if favoured (ex. human birthweight)
Directional selection
Favours an increase or decrease in a phenotypic trait from the current population average, can follow dramatic change in enviornment
Disruptive selection
Favours 2 or more variations that differ from the population average, typically 2 extremes
ex. humming bird bill length
