Lecture Test 4 Flashcards
What is a species?
A population of organisms that can, and normally does, interbreed successfully with one another but not with members of other populations (other species).
An evolutionarily independent population or group of populations.
Morphospecies concept
Distinguishing features are most likely to arise if populations are independent and isolated from gene flow
Pluto’s theory of evolution
Each organism as perfect and unchanging
Typological thinking
Aristotle’s theory of evolution
“Great Chain of Being”
Species are fixed
Higher and lower order
Species immutability
Carl Linnaeus
1735 “Systema Naturae”
Classification of all species
Humans as Primates
Georges-Louis Leclerc, Comte de Buffon
Used Newton’s physics
Age of Earth is 70,000 years
Earth has history – origins of life
Change through migration
Thomas Malthus
Political economist, not biologist
Population effects in humans
Will the food supply keep up?
Will those with the strongest traits survive?
Jean-Baptiste Lamarck
Animals seemed to have acquired traits
Giraffe – long neck
Reasoned that through use and effort the neck became longer
Problems (does it explain the facts)?
Georges Cuvier
Naturalist
Anatomist and fossil expert
Concept of extinction as ordinary
99% of all species
Charles Lyell
Rock cycle, erosion, fossils
Age of the Earth in millions
Alfred Russell Wallace
Geographic distribution of animals
Led to exploration of plate tectonics and biogeography
Gregor Mendel
Genetic variation
Offspring ratios
Inherited and non-inherited traits
Rev JS Henslow
Naturalist and teacher
Encouraged Darwin with field studies
Introduced Darwin to geology
Passed on the opportunity to travel on the HMS Beagle
Artificial Selection
by breeders can produce major changes in body form
Variation Choose particular animals to reproduce Develop new breeds with an increase or decrease of particular trait
Natural Selection
will also lead to major changes over time
Variation Differences in survival, growth, and reproduction More offspring from those variants that are best adapted to particular environment
Geologic time
Vastness 4.6 billion years Eras Periods Earliest life ~3.4-3.8 billion years 24 hour clock Humans at very end (last few seconds)
Fossils
Any evidence of former life forms
Bones/skeletons, teeth, animal tracks, leaves and stems, etc
Rapid covering, right environmental conditions (sedimentary)
Transitional Forms
Intermediate between older & younger species
Tiktaalik as example
Extinction
Complete loss of a species from Earth
Periodic
Vestigial Traits
Human traits Pseudogenes Anatomical parts Other species Lungfish fins Cave fish eyes Dew claws Wings on flightless birds and insects
Geographical distribution
Variation across continents
Similarities of species
Homology
Genetic homology DNA sequences are conserved Mutations Developmental homology Embryonic similarities
Darwin’s Postulates
Individual organisms in a population vary
Some of the trait differences are heritable
More offspring are produced than can survive
Some survive to produce offspring, some do not
Those that survive best and reproduce are not a random sample
Individuals with certain traits do better
The environment picks the survivors
Today’s Synthesis
Evolution by natural selection occurs when heritable variation leads to differential reproductive success
Fitness
Survival of the fittest
reproductive success
adaptation
Modification for a certain enviornment
a trait with a current functional role
leads to natural selection
Limitiations of natural election
Fitness trade-offs
Pleiotropy
Lack of genetic variation
Cloning?
Historical constraints
All traits have evolved from earlier traits
evolution works on populations, not individuals
evolution works on populations, not individuals
What is the drving force of microevolution?
changes in alleles
n=
total number of individuals
for the harvey weinberg law to hold true certain conditions must be met:
Population is very large (infinite?) Mating is random Mutations do not occur (or are equal) Migration is nil or equal Natural selection is creating no selection pressure Generations are non-overlapping Parents produce multiple offspring
HW inbreeding
Mating among relatives
Leads to homozygosity
Does not promote evolution
sexual selection
Courtship, dominance of a male
Female choice
May leads to sexual dimorphism
May drive evolution
immigration
inward
emmigration
outword
