Evolution Flashcards
Who conceived the Scala Naturae, or “ladder of life”?
Aristotle
What is the ladder of life?
chain of being, with simple organisms at bottom and more complex at top
each viewed as fixed in place; unchanging
What happen during the age of exploration?
16th century European explorers traveled globe
explosion of new plants and animals brought back and the ladder of life was being challenged
What is biogeography?
worldwide distribution of plants and animals
Evolution of major animal groups _________________ on the Earth
correlated with known changes in the distribution of land masses
First mammals arose ______ when Australia was still connected
225 mya
________ mammals arose 80 mya after Australia separated
Placental
Australia has __ large, terrestrial placental mammals
no
_________ structures in different species suggested relationships
homologous
What does the arm of a human, a turtle leg, and bat wing have in common?
all have same bones in same basic pattern
What does the homologous structures in different species suggested?
strongly suggests modification from common ancestor (anatomical homology)
Homologous bones example and suggest?
bird and bat wing; evolved from common ancestor
Analagous wings example and suggest?
bird and insect wing; evolved from different tissues for similar function
______ fossils usually in bottom (oldest) sediment layers; more ________ near top
simplest; complex
Grand Canyon shows results of ____ million years of sedimentation, eroded by Colorado River
40
What did the “Fishapod” (Tiktaalik roseae) show?
Illuminates steps leading to evolution of tetrapods
What type of fossil was the “Fishapod”?
Transitional form
What is a transitional form?
provides link between earlier and later forms
What did Jean Baptiste de Lamarck do and what did he call it?
first person to propose mechanism of evolutionary change; “Inheritance of Acquired Characteristics”
Lamarck thought changes resulting from ________ could be inherited
use or disuse
Lamarck idea is now a __________ idea
discredited
What did Darwin observe?
fossils of extinct species similar to existing species in same areas–suspected descent from ancestor
Darwin noted _____ among individuals in populations of the ________
variation; same species
Darwin reasoned that any difference that provides an _______ in gaining resource will enhance ______________
advantage; survival and reproduction
What are the 2 critical ideas that led to the theory of evolution?
variation among individuals
competition for limited resources
What are Darwins 4 postulates?
- variation exists among individuals that make up a population
- Some of the trait differences are heritable
- Survival and reproductive success is highly variable
- The subset of individuals that survive best and produce the most offspring is not a random sample. Some are more likely to survive and reproduce than others.
Natural Selection is the __________________
main mechanism of evolution
differential survival and reproduction as a result of __________________
variation among individuals
traits that improve survival & reproduction in a given environment are called __________
adaptations
____________ is now known to be a change over time in the genetic composition of a population
evolution
Key difference from Inheritance of Acquired Characteristics is what?
populations evolve, not individuals
_________ is the raw material for natural selection
variation
new variations arise from _______
mutations
individuals vary due to ___________
genetic recombination
What are some genetic recombination?
crossing over
independent assortment of alleles
fertilization and sexual reproduction
alleles shuffled when making gametes; no _______________
two individuals alike
individuals have a __________ (Think genes)
genotype
populations have a __________(Think genes)
gene pool
__________ by humans for specific traits in plants and animals has revealed ____________
selection; genetic variation
Darwin reasoned that ___________, acting over vast spans of time, could _________________
natural selection; produce tremendous variation
What are the 3 different types of selections in the environment?
stabilizing selection
directional selection
disruptive selection
What is stabilizing selection?
selection favors average phenotypes over extremes
What is directional selection?
selection favors phenotypes at one extreme or the other
What is disruptive selection?
both extremes favored over intermediates
What is the most common way a new species arise?
allopatric speciation
if individuals disperse to form a ___________, or a ___________ divides a population, each is _______________
new population; geographic barrier; genetically separate
if populations diverge enough, may become two _____________
separate species
Evolution produces a ____________, not a progressive “ladder”
tree of life
