Evolution Exam 1
The Great Chain of Being
European idea that every species was a link on a chain extending from lowest forms to humans and on to spiritual beings. All links and been designed at the same time during creation and would never change. Once all the links were discovered and described, the meaning of life would be revealed. ❖ Adapted in the Middle Ages and Renaissance ❖ Fixed hierarchy ❖ Not very detailed
The linnean society 1858
Letters from both Darwin and Wallace were presented
lobe-finned fishes
Living example is the Coelacanth. Lobed fins for moving along bottom and have a short chain of bones that is homologous to the tetrapod limb
locus
Location of a gene on a chromosome
species have fixed properties
Prior to 1859, the prevailing world view. This idea traces back all the way to the Theory of Forms by Plato (428-348 BC) and Aristotle (384-322 BC).
Nicolas Steno (1638-1686)
Recognized that fossils used to be living things by analyzing 'tongue stones' (shark teeth)
aerobic respiration
Respiration that requires oxygen to make ATP
Homoplasy
The separate evolutionary development of similar characteristics in different groups of organisms. Can happen due to either convergent evolution or reversals.
horizontal gene transfer
The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.
diapsids
Two holes on each side of the head (reptiles such as dinosaurs); dominated the ecosystem until a mass extinction 65 mya
Tiktaalik
"missing link" thought to be a transitional form between fish and tetrapods.
most organisms don't fossilize
-Hominid leaves foodprints in the mud -Hominid dies near water -Vultures and other scavengers pick away at muscles/organs -Remaining flesh rots away, leaves bones behind -Water level rises, covering bones and footprints -Thick sequence of sediments accumulates over bones, gradually fossilize bones -Hundreds of years later, erosion exposes bones to footprints its a game of chance
Natural Selection (darwin's mechanism of change)
1. High birth rates predict exponential growth of populations 2. Population sizes are normally stable 3. Natural resources are limited 4. No two individuals are exactly the same 5. variation is inheritable
Darwin's two major hypotheses (1859):
1. Organisms have descended with modification, from common ancestors. 2. The chief cause of modification is natural selection acting on hereditary variation.
Characteristic required for terrestrial life
1. resistance to desication 2. structural support 3. new reproductive strategies 4. new respiration strategies
Inferences made based on Darwin's natural selection
1. since more individuals are born than can survive, ther must be a fierce struggle for life/existence 2. Survival in the struggle for existence is not random, and depends on heritable variation 3. Over generations, heritable variation that increases survival will increase in frequency in populations
Age of first Eukaryotes
1.8 bya
the age of the universe
14 billion years
the cambrian explosion
20 million year period where all living lineages first appeared on the fossil record
large plants come around
360-300 mya and those species are mostly now extinct
oldest known trackway of a vertebrate age
390 mya
solar systems age
4.6 billion years old
oldest known terrestrial animal age
428 mya
first chordates
515 mya during the cambrian
Ediacaran fauna
575-535 mya
Sahelanthropus
7 mya; oldest bipetal hominid
age of our galaxy
< 10 billion
modern synthesis
A comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution. (mendelian inheritance, genetic variation, natural selection)
a protein coding gene
A gene encoding a protein.
the possibility of rejection by observation and experiment
A hypothesis that cannot be subject to ________ cannot be regarded as scientific.
Darwin was prompted to publish his theory of evolution by
A letter from Alfred Russel Wallace that proposed similar ideas of common ancestry and natural selection. He wanted to be the first because he had spent his whole career on these findings
natural selection
A mechanism that can lead to evolution, whereby differential survival and reproduction of individuals cause some genetic types to replace others.
nonsynonymous mutation
A mutation in a gene that changes the amino acid sequence of the protein that gene encodes.
synonymous mutation
A mutation that does not result in a different amino acid
consensus tree
A phylogenetic tree that has all the features shared by the equally parisimonious cladograms in a study, while leaving conflicts unresolved
gene
A segment of DNA on a chromosome that codes for a specific trait
codons
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
Jean-Baptiste Lamarck (1744-1829)
Adaptation occurs through inheritance of acquired changes. • Life driven from simple to complex • Complex species descended from microbes • Microbes continually generated spontaneously
cladistics
An approach to systematics in which organisms are placed into groups called clades based primarily on common descent and homologous traits
exaption
An existing structure that is co-opted after having previously served a different function ex. feathers evolved before flight
Pangenesis
An incorrect idea that acquired characteristics are passed on; darwins hypothetical mechanism for heredity.
Archaeopteryx
An intermediate fossil that shows both reptile and bird characteristics.
chordate
Animals with a notochord, most have a backbone; arrived in the fossil record 515 mya
Biological Evolution
Any change in the inherited traits of a population that occurs from one generation to the next.
biological evolution
Any change in the inherited traits of a population that occurs from one generation to the next.
gemmules
As proposed by Darwin, the units of inheritance, supposedly accumulated in the gametes so they could be passed on to offspring.
Meiosis
Cell division that produces reproductive cells in sexually reproducing organisms (reduces ploidy)
1859
Charles Darwin publishes On the Origin of Species highlighting natural selection
acanthostega
stem-tetrapod; primarily aquatic, shallow water, internal gills, 8 digits/foot, no wrists 365 mya
Phylogenetics
the analysis of evolutionary, or ancestral, relationships between taxa
Snowball Earth Hypothesis
the hypothesis that glaciers covered the planet's landmasses from pole to pole 750-570 million years ago, confining life to very limited areas. Theorized to be due to volcanic activity and thawed rapidly (over 1 million years)
convergent evolution
the independent evolution of similar features in different lineages (whales becoming more aquatic)
translation
the process in which mRNA molecules are decoded to produce a protein
Taxonomy
the science of describing, naming, and classifying species.
Stratigraphy
the study of rock layers and the sequence of events they reflect
catastrophism
theory that states that natural disasters such as floods and volcanic eruptions shaped Earth's landforms and caused extinction of some species highly debated in the 1700s
Francis Galton
transfused blood between dissimilar breeds of rabbits to disprove pangenesis
systematics
use of phylogenetics to decide how life should be classified
chromosomes
vary in size, mitochondrial DNA is circular.
tetrapod
vertebrates with four limbs, or descended from vertebrates with 4 legs
The age of the Earth
was debated in the 19th century; varied from 20 million to 4.6 (most accurate to date)
principle of maximum parsimony
we should first investigate the simplest explanation that is consistent with the facts and requires the fewest assumptions or evolutionary changes
artiodactyls
whales are most closely related to this group (not directly related just share a common ancestor)
physicists discovered the structure of atoms, and further, radioactive decay
what lead to a reliable and precise method for estimating the age of rocks?
independent assortment
which copy ends up in each cell is random
Basic atom discoveries that lead to the use of radiometric dating
• All atoms are composed of protons, electrons, and neutrons. • The number of neutrons in atoms of the same element can vary (isotopes). • Some isotopes are stable and others are unstable (radioactive).
Voyage of the Beagle
• Collected many fossils and living organisms • Studied geology while reading Principles of Geology by Lyell
George Buffon (1707-1788)
• Earth formed according to laws of physics and chemistry • Older than previously thought • Life emerged as distinct types • Transformed when environment changed
Darwin's insights
• He was the first propose a correct mechanism for how life changed over time. • He published an incredibly thorough catalog of evidence for natural selection.
Whales share synapomorphies with mammals
• Mammary glands • Three middle ear bones • Hair (in developing embryos)
The life of Charles Darwin (1809 - 1882)
• Medical school in Edinburgh Preferred to study nature • Invited to serve as unofficial naturalist for the HMS Beagle in 1831 • Transferred to become a clergyman at Cambridge
Carolus Linnaeus (1707 - 1778)
❖ Father of modern taxonomy. ❖ All living things are organized into a nested hierarchy of taxa.
The age of earth
Using different tools, scientists have consistently arrived at the same answer. The solar system and are planet are both around 4.6 billion years old.
Birds (Aves)
Which is a legit clade: Birds or Reptiles?
scientific theory
a comprehensive, coherent body of interconnected statements, based on reasoning and evidence, that explain some aspect of nature.
paraphyletic clade
a grouping that consists of an ancestral species and some, but not all, of the descendants
fact
a hypothesis that has acquired so much supporting evidence that we act as if it is true.
teleost
a lineage of bony fish that comprises most living species of vertebrates. They include goldfish, salmon, and tuna.
Radiometric dating
a method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample.
mRNA
a molecule of RNA that carries genetic material to the ribosome, where it can be translated into a protein
germ-line mutation
a mutation occurring in gametes; passed on to offspring
paleontology
a science dealing with prehistoric life through the study of fossils: • Fossils resemble, but are not exactly the same as modern species • Many past species are extinct
oldest recognizable organism
a sponge ancestor about 600-650 myo
first evidence of grasses
a tiny bit of tissue in dinosaur droppings that are 70 million years old
Phylogeny
a visual representation of the evolutionary history of populations, genes, or species
somatic mutation
affect cells in the body of an organism and are not heritable
2 billion years
all organisms lived in the ocean and were very small for the first _____
Decent with modification
all species share common ancestry, changes occur through natural selection.
Burgess Shale
an exceptionally rich site for Cambrian fossils - 65,000 specimens, +93 species
Acquired characteristics
an organism pass on characteristics it acquired through use or disuse during its lifetime
polytomy
an unresolved pattern of divergence
Carbon-14
an unstable isotope that is constantly being produced in the atmosphere. has a half-life of 5,730 years - allowing scientists to date organic material that is less than 50,000 years old.
Using isotopes
analysis of fossil teeth: Terrestrial animals drink freshwater; marine animals drink saltwater. we can predict based on the O18/O16 ratio we can predict where and when whales transitioned to salt water.
terrestrial vertebrates
appear 150 million years after aquatic
pseudogenes
are DNA sequences that resemble functional genes but have lost their protein coding ability or are no longer expressed
NO
are there any currently living species that are ancestral to another
Lord Kelvin
argued that Earth's rate of heat lost showed that the age of the planet was less than 20 million years. His estimates were based on flawed assumptions about the structure of the planet's interior.
Misconseption of the tree of life
assumes genetic info is transferred vertically from parents to offspring
2 types of chromosomes
autosomes and sex chromosomes
hindlimb loss in cetaceans
begin to form in cetacean embryos, but do not fully develop
160 mya
birds split from other dinosaur lineages
nodes of phylogenetic trees
branch points in a phylogeny where lineages split (speciation events)
clade
branches of a phylogeny that contain a node and all of its decedents
divergence
can occur such that closely related species no longer resemble each other because they have adapted to different ecological conditions
structural mutations
caused by improper crossing over and cause variation in chromosome size
Mutation
change in a DNA sequence that affects genetic information
a protein
coding gene is a gene whose sequence codes for a protein
monophyletic clade
consists of the ancestor species and all its descendants
origins of life
could have happened more than once (various extinction events), all have a common ancestor (life only used the L optical isomers of amino acids)
William Smith (1769-1839)
created the first geological map; noticed that different rock layers contain distinct fossils.
defining relationships in phylogentic trees
defined by the order of branching, NOT by the linear tips of the tree.
polyphyletic clade
describes a group that does not share an immediate common ancestor (not a legitimate clade)
sex chromosomes
differ in copy number between males and females
Mary Anning
discovered several species of extinct marine reptiles
Drought Hypothesis
disproven; fish were driven on land by a Devonian drought 'dry lake'
The age of fossils
don't typically contain the radioactive isotopes used in radiometric dating. Their age can be estimated by using radiometric dating to determine the age of the layers of rocks around them.
Law of Segregation
during gametogenesis, the 2 copies of each hereditary factor segregate randomly so that each gamete carries one copy
segregation
during the final stages of meiosis, each pair of chromosomes separates, so only a single copy ends up in each gamete.
585 mya
earliest animal tracks
Great Oxygen Event
early cyanobacteria produced oxygen as a waste product of photosynthesis, oxygen was toxic o most life at the time and caused mass extinction
genetic recombination
early in meiosis, homologous chromosomes pair up and may exchange segment of DNA. - produces new combos of alleles not present on a single parental chromosome.
Multicellularity
evolved multiple times independently; advantages: - large size to protect from predation - more complex multicellularity leads to division of labor.
Prokaryotes
first on land (microbial mats; found in South Africa)
proximate explanations
focus on a mechanistic understanding of how something happened.
ultimate explanations
focus on historical perspectives of how something came to be.
selective pressures
forces in the environment that influence reproductive success in individuals
mammalian middle ear
fossils and phylogeny document the transition; are homologous to synapsid jaw bones
Life
generally defined as an assemblage of molecules that can capture energy from the environment and replicate itself. The precise age of life on Earth is not yet known. it could not establish itself on Earth until the planet became habitable.
Genotype
genetic makeup of an organism
Taxa
groups of organisms that taxonomists judge to be cohesive units.
The collision that created the moon
happened during heavy bombardment that happened 4.4 billion years ago and stopped 3.8
particulate inheritance
hereditary determinants maintain their integrity from generation to generation
law of independent assortment
hereditary factors assort independently during gamete production
stored in DNA
heritable variation
in the 1600s
naturalists began developing systematic ways to classify, name, and sort species.
350 mya there were
no flowering plants, teleost fish, no mammals, and no birds
Autosomes
non-sex chromosomes
Ploidy
number of sets of chromosomes in a cell
Inheritance of variations
offspring are similar, but not identical, to their parents
blending inheritance
offspring inherit traits that are a blend of the parental traits
136 myo
oldest well-accepted fossil of a flowering plant
coelacanth
one of the closest living relatives to tetrapods; 400mya
Phylogenetically informative
only shared, derived characters are
biomarkers
organic molecules that indicate the presence of life such as fragments of DNA, amino acids, and isotopic ratios.
outgroups
organism that are outside of the group being considered, but are used to infer what is ancestral and what is derived.
50%
percent of your genetic material with your mother, father, and siblings
Extinction
permanent loss of a species
hypothetico-deductive method
positivist research design based on the development and systematic testing of hypotheses.
sexual reproduction
production of offspring by combining genetic information from two individuals of different types
Charles Darwin's theory of natural selection
proposed that cetaceans descended from mammals that lived on land and their lineage evolved into a marine mammal
transcription factors
proteins that bind to specific DNA sequences and turn gene expression on or off
James Hutton (1726-1797)
realized that rocks formed through imperceptibly slow changes. • Observable processes produce small changes that accumulate over time (gradualism/uniformitarianism). • The Earth must be old.
gene control region
refers to an upstream section of DNA that includes the promoter region as well as other regulatory sequences that influence the transcription of DNA
Dinosaurs
replaced synapsids as the dominant terrestrial vertebrate after they emerged in the fossil record around 240 mya
tips or terminal nodes
represent the lineages being compared
branches of phylogenetic tree
represents a population through time
the root node
represents the most recent common ancestor of ALL the species in a tree
Early land plants
resemble mosses and liverworts
evolution reversal
reversion back to ancestral character state
Processes that generate
sexual reproduction, recombination, mutation
Synapomorphy
shared derived character
homology
similarity resulting from common ancestry
Lagerstätten
sites with an abundant supply of unusually well-preserved fossils from the same period of time.
velociraptors
slightly bigger chickens, had feathers and wing bones that resemble quill nodes
non-coding regions of DNA
In the human genome, over 98% of DNA is classified as non-coding DNA and can be transcribed to regulatory non-coding RNAs
August Weismann
Cut the tails of mice for 22 generations and observed the offspring. He found that the acquired characteristics of shortened tails was not inherited.
the central dogma
DNA -> RNA -> Protein
tumbridge wells
Darwin studied and measured the erosion here to help quantify the age of Earth
eusthenopteron
Devonian fish. "the fish with legs," similar limb and bone structure, internal nostril. 385 mya
Alleles
Different forms of a gene at the same locus
Mendel
Father of Genetics; responsible of the Law of Inheritance
Fossils provide clues about behavior, development, and cellular structure
Fossils suggest nesting behavior seen in living birds first evolved over 150 million years ago in feathered dinosaurs. - Egg fossils at various stages -Identification of melanosomes in Anchiornis suggests they had brightly colored plumage.
Synapsids
Gave rise to mammals and their extinct relatives; emerged 600 mya and became the dominant terrestrial vertebrates
Uniformitarianism (lyell)
Mechanisms of change are constant over time, same geological processes are operating today as in the past and at the same rate Earth's landscapes have been shaped by the cumulative action of gradual processes observable today.
The limits of radioactive decay
Most radioactive isotopes were formed in ancient stars and were present on Earth at its formation. Scientists do not find short-lived isotopes in Earth's rocks.
Stromatolites
Oldest known fossils formed from many layers of bacteria and sediment. (most widely accepted evidence, 3.45 bya)
scientific theory of evolution:
The explanation of how modification occurs and how ancestors give rise to diverse descendants.
Darwin's long ass book title
The origin of species by means of natural selection of the preservation of favored races in the struggle for life
biological evolution is not
in an individual, must be a group a post birth deformity
the genome
includes all the hereditary information of an organism. - 23 chromosomes in the human genome containing 3.2 billion base pairs - the human genome is diploid, containing 2 homologous copies of each chromosome
hypothesis
is an informed conjecture or statement of what might be true.
unstable to stable
isotopes decay spontaneously from
half-life
length of time required for half of the radioactive atoms in a sample to decay
internal nodes
lies the most recent common ancestor of all species in the tree; represent ancestral species
By the early1800's, scientists had realized
life and the planet had changed and the record of that change can be studied. Why species emerged and disappeared over the history of life was a subject of fierce debate.
Hadean Eon (very early Earth):
likely formed from the collision and aggregation of smaller bodies, which produced enormous heat. formed a solid crust as it cooled & oceans of liquid water most likely formed by 4.5 bya.
complex multicellular organisms
made the transition to land much later (plants, fungi, and animals)
homosapien
modern human; 300,000 years old
