SCIENCE Flashcards
nature provided the variation among different organism and humans selected those variations that they found useful
Artificial Selection
is the slow gradual change in a population of organisms over time
Evolution
are populations or groups of populations, within and among which
individuals actually or potentially
interbreed (biological species concept
by Ernst Mayr)
Species
New species evolve
Speciation
Evolution By Natural
Selection Concepts
The Struggle for Existence
• Survival of the fittest
• Descent with Modification
(compete for food, mates,
space, water, etc
The Struggle for Existence
strongest
able to survive and reproduce)
• Survival of the fittest (
new species arise from common ancestor replacing less fit
species
• Descent with Modification
ability of an individual to
survive & reproduce
• Fitness
• inherited characteristic that increases an organisms
chance for survival
Adaptation
is central to the process of evolution
• Fitness
• Structures that have different mature forms
but develop from the same embryonic tissues
• Strong evidence that all four-limbed animals
with backbones descended, with modification,
from a common ancestor
• Help scientist group animals
Homologous Body Structures
early stages of
vertebrate development
embryo
are the processes
which enables evolution to take
place
Mechanisms
Short time scale events (generation-to-generation) that change the genotypes and phenotypes of populations –Changes in a population’s gene pool over time. –Not possible without genetic variability in a population
Microevolution
random changes in DNA
ultimate source of new alleles
Mutation
(movement of genes between
pop’s)
. Gene flow
change in gene pool due to
random/chance events
)
Genetic drift (
Changes in the structure of the DNA
▪ Adds genetic diversity to the population
▪ May or may not be adaptive
Mutation
▪Two major types of mutations:
1.Gene mutations (nucleotide)
2. Chromosome mutations
(structural)
movement
of alleles into a population
- Immigration
movement of
alleles out of population
Emigration
in allele frequencies over generations brought about by
chance
Random change
change the gene frequency could include fire, typhoon or
human-made such as building dams and clearing forests
Random events
Occurs when a population’s size is reduced for at least
one generation and reduces genetic variation
Bottleneck Effect
New population
established by very small
number of individuals
Founder Effect
rudimentary and
sometimes useless
body part
Vestigial structure:
Long term, large scale evolutionary changes
through which new species are formed and
others are lost through extinction
▪ Obvious changes that happen over time.
Macroevolution
Two Processes of Macroevolution
- speciation
2. extinction
▪ Two species arise from one
Speciation
offspring of a
male donkey and a female horse
Mules
A large scale evolution of a group of species into many
different species.
–Leads to two outcomes:
1) Reduces competition between different species
2) New species evolve and exploit different niches as
competition within species increase because of
limited resources.
Divergent Evolution/Adaptive radiation
How an organism lives
and interacts with its
environment.
Niche
The evolution of similar traits in
distantly related species.
▪ Two different species living in similar
environments under similar selective
pressures will evolve similar traits that
allow them to occupy similar niches
Convergent Evolution
▪ Two groups of plants
- Cacti – deserts of South America
2. Euphorbia – deserts of South Africa
▪ One species evolves in response to
evolution of another species.
▪ Interactions between species can cause
microevolution
Coevolution/Cospeciation
Species A evolves
to become species
B in a long gradual
process.
GRADUALISM
Evolution is SLOW with brief
periods of rapid
development of new
species
PUNCTUATED EQUILIBRIUM
Periods of time where change in species’
structure or genetic composition are not
apparent.
STASIS
Species that exhibit unchanged
characteristics and genetic composition
throughout long periods of time
living fossils.
• often be reduced to a mathematical statement • Specific statement based on empirical data
Scientific Law
Often seeks to synthesize a body of evidence or observation of a particular phenomena
Scientific Theory
is a branch of astronomy that involves the
origin and evolution of the universe, from
the Big Bang to today and on into the
future.
COSMOLOGY
– The universe formed approximately 13.7 billion years ago from a cataclysmic expansion which hurled all matter and created space. • Widely accepted theory for the origin and evolution of the universe
Big Bang Theory
The universe has always been expanding outwards and continuously creates matter
Steady State Theory
megadense point
Singularity.
States that after the Big Bang, the formation of the universe never
stopped and is continuously making other different universes
(multiverses) which could be different or similar to our own in
terms of physical laws
Eternal Inflation of the Universe
States that a similar contraction and return to that singularity should be possible.
Big Crunch and the Oscillating Universe Theory
is a situation that scientists predicts
how the universe will end.
Big Crunch
The modern accepted theory of the origin of the Solar
System.
The first stars are formed from this contraction of gases and
nuclear fusion
Solar Nebula Theory/Modern
Laplacian Theory
What are the Earth’s four subsystems?
- Atmosphere
- Biosphere
- Lithosphere
- Hydrosphere
energy and/or
matter move in
and out
Open system
: no exchange of
energy and matter with
surroundings
Closed system
Largest of the four spheres • Comprises the solid portion of the Earth • Extends 6,400 km from the surface down to the core
Geosphere
Layers of the Geosphere
- Crust
- Mantle
- Core
- Lithosphere
- Asthenosphere
hot, ultramafic rock; it represents
about 68% of Earth’s mass
Mantle
dense metallic (mostly composed of iron); makes about 31% of the Earth
Core
is composed of both the
crust and the portion of the upper mantle
that behave as a brittle and rigid solid
Lithosphere
is partially molten upper
mantle material that behaves plastically
and can flow
Asthenosphere
Layer of gaseous
envelope that surrounds the planet on the
surface and extends thinly
into space
Atmosphere
Layers of the Atmosphere
• Troposphere – lowest part and the part we
live in
• Stratosphere – contains much of the ozone
• Mesosphere – temperature decreases with
height
• Thermosphere – temperature increases with
height
• Exosphere – contains mainly oxygen and
hydrogen
Includes all forms of life on Earth • Includes organisms found in the deepest parts of the oceans and highest parts of the atmosphere
Biosphere
proposed that the planets
revolved around the sun
(Heliocentric Model)
Nicolaus Copernicus
1473-1543
Devised the most precise instruments available before the invention of the telescope for observing the heavens
Tycho Brahe
1546-1601
• derived the 3 basic laws of planetary motion • Elliptical path of a planet around the sun
Johannes Kepler
1571-1630
Laws of Planetary Motion
- Law of orbits
- Law of areas
- Law of periods
– planets orbit the sun
elliptically
Law of orbits
– a line connecting a planet to
the sun covers an equal area over equal
periods of time
Law of areas
allows us to establish a clear relationship between a planet’s orbital period
and its distance from the sun
• Law of periods
• Played a major role in the scientific revolution of the 17th century • Telescopic confirmation of the phases of Venus • Discovery of Jupiter’s moons • Observation and analysis of sunspots • Invented an improved military compass
Galileo Galilei
1564-1642
• Law of Universal
Gravitation
• Laws of Motion
Sir Isaac Newton
1642-1727
