I.
Where did the simple building blocks of life come from? Some possibilities…
1. They were synthesized on earth by abiotic means from gases and other chemicals already present.
2. They were synthesized on earth by abiotic means from material originating from outside the planet
3. They were synthesized in space and deposit on earth
II.
Emergence of the first living cell.
1. A source, or means of synthesizing, small organic molecules such as amino acids and nucleotides
2. Joining monomers into polymers: amino acids  proteins; nucleotides  nucleic acids, etc.
3. Packaging complex molecules into membrane bound structures – spatial compartmentalization
(allowing maintenance of separate internal chemistry)
4. Rise of self-replicating molecules making inheritance possible. => Chemical Evolution
III.
Miller and Urey 1953 experiment:
It showed that organic molecules can be formed from abiotic environment from simpler molecules when
imposed to energy source \ with the input of electrical impulses.
IV.
RNA World Hypothesis
“First “genes” may have been short pieces of RNA able to replicate without the aid of enzymes (perhaps on clay
surfaces).” (1967: Carl Woese, Leslie Orgel, and Francis Crick)
Ribozymes - certain types of naturally-occurring RNA molecules can behave as enzymes, catalyzing their
own assembly. (ribonucleic acid + enzyme) molekula RNA obladaysuaya katalistecheskim deistviem.
RNA World = hypothetical period in the development of life on earth when RNA served both as genetic
material and primary biological catalyst.
V.
Big bang ~ 13.7 bya
Formation of solar system and earth ~ 4.7 bya
Homo sapiens ~ 150,000 ya
First life ~ 3.9-3.5 or 3.8 bya
VI.
Two Big Ideas from The Origin of Species:
1. Evolution explains both the unity and diversity of life
2. All organisms are related to each other as a result of descent from a common ancestor
3. Descent with Modification ** in the first edition of “The Origin of Species” Darwin did not use the word
“evolution” until the end of the book; instead he talked about “descent with modification”
4. “Tree of Life” concept
2. Natural Selection provides the mechanism for adaptive evolution
* Only inheritable traits are modifies by natural selection (not acquired traits)
* Only natural selection gives rise to adaptive traits but it’s not the only mechanisms by which populations
change (there is also genetic drift and neutral selection)
1
VII.
Natural Selection (Differential Reproductive Success) => Evolution ( Descent with Modification
by means of )Natural Selection
Evidence for Evolution:
1. Artificial Selection: selective breeding of domesticated animals and plants to promote the occurrence
of desirable inherited traits in the offspring.
2. The fossil record: the chronicle of evolution over the millions of years of geological time in the order
in which the fossils appear in the rick strata.
3. Biogeography: studies the distribution of life forms over geographical areas
Closely related species tend to be found near each other (inference is that they had common ancestor)
– In general, the biogeographic distribution of species supports evolution.
– Historical biogeography considers both current and fossil species
• Example #1: almost all mammals in Australia are marsupials
• Example #2: Species on the Galapagos Islands are most similar to species on the South
American mainland
4. Comparative Anatomy: Homology(The similarity in-between different species and different phylogenetic groups that shows
which ones are more closely related based on their amount of traits in common example/ similarities between chimps and humans compared to
the similarity between humans and a fish. This also covers similarity in genes and you could even say that different non-living things like TVs
have homology.):
Similarity in characteristics resulting from common descent
5. Comparative embryology (comparison of the embryos)
•
VIII. ***Population is the smallest unit that can evolve. Population is a group of individuals of the same
species living at the same place at the same time. Population Genetics studies how the genetic makeup of a
population changes over time. Individuals within a given population tend to be more closely related to each
other than to individuals from different populations. Natural selection acts on individuals, but the
evolutionary impact is only observable in populations over time.
–
***Gene pool = all the genes at a population at any one time, consists of all alleles at all gene loci in
all individuals in a population
• Each allele at a given loci has a certain frequency in the population
– The sum of all the allele frequencies = 1
– By convention, when there are two alleles, the frequencies are represented by p and q
– p + q = 1 (for a given gene)
IX.
***Natural selection acts on individual organisms but their genetics do not change as a result. Genetic
makeup of populations changes over time. Natural selection doesn’t pass on acquired traits. Evolution is
not goal directed. It has no purpose or end in sight. It acts in the here and now only. What is currently an
advantage, may become a disadvantage if conditions change.
X.
Evolution is not goal directed. It has no purpose or end in sight. It acts in the here and now only. What is
currently an advantage, may become a disadvantage if conditions change.
XI.
Microevolution = Changes in the relative frequencies of alleles within a population over time (In other words,
changes in the gene pool, over time)
2
XII.
The source of genetic variation (unique combinations of alleles) in a population:
1. Independent orientation of homologous chromosomes in meiosis I
2. Crossing over
3. Random fertilization
XIII. The Hardy-Weinberg principle (1908): can indicate whether a population is evolving.
The frequency of alleles and genotypes remains constant in a population if only Mendelian segregation
and recombination occur (Hardy-Weinberg Equilibrium)
Закон Харди — Вайнберга — это закон
популяционной генетики — в популяции бесконечно
большого размера, в которой не действует отбор, не
идет мутационный процесс, отсутствует обмен
особями с другими популяциями, не происходит дрейф
генов, все скрещивания случайны — частоты генотипов по какому-либо гену (в случае если в популяции есть два
аллеля этого гена) будут поддерживаться постоянными из поколения в поколение и соответствовать уравнению
So, the conditions for the populations are:


1. Large gene pool
2. No gene flow ( no migration of individuals or gametes in or of the population )
3. NO mutations
4. Mating must be random
5. All individuals must have equal reproductive process
XIV.
XV.
GENETIC drift - change in a gene pool by a chance
Bottleneck effect = genetic drift resulting from a drastic reduction in a population size. Эффект
бутылочного горлышка — сокращение генофонда (т.е. генетического разнообразия) популяции вследствие
прохождения периода, во время которого по различным причинам происходит критическое уменьшение её
численности, в дальнейшем восстановленное. Сокращение генетического разнообразия приводит к изменению
относительных и абсолютных частот аллелей генов, поэтому данный эффект рассматривается в числе факторов
эволюции.
XVI.
The founder effect = random change in a gene pool that occurs in a small colony of population.
явление снижения и смещения генетического разнообразия при заселении малым количеством представителей
рассматриваемого вида новой географической территории.
XVII. Genetic grift and natural selection both contribute to evolution, but only natural selection leads to
adaptive changes.
XVIII. Mutations are the ultimate source of variation in a population. Much of variation is neutral; meaning that
variation doesn’t contribute to greater reproductive success.
XIX. Three sources of altering gene frequency in a population:
 Natural Selection
– variation in reproductive success
– leads to adaptive evolution
3
•
Genetic Drift - Change in gene pool due to chance
– Bottleneck effect
– Founder effect
• Gene Flow
– reduces genetic
differences among
populations
XX. Evolutionary fitness = Any trait that allows an individual to pass more copies of its genes to the next
generation. The “fittest” isn’t necessarily the strongest, smartest, or fastest but the one who gets more of
his/her genes into the next generation. Relative Fitness: the contribution an individual makes to the gene
pool of the next generation relative to the contribution of other individuals
XXI. Intrasexual selection: direct competition for mates usually seen in males fighting each other for females
XXII. Sexual Selection is a special case of natural selection. In many species this leads to sexual dimorphism
Among vertebrates, males are often larger and showier Examples of such differences include differences in
morphology, size, ornamentation and behavior.
XXIII. Intersexual selection: (mate choice) individuals of one sex (usually females) select mates based on external
characteristics
XXIV. Diploidy allows recessive alleles to be “hidden” from selection pressures. Only homozygous individuals
display recessive phenotype, therefore the recessive allele is only subjected to natural selection when there
are two copies in one individual. Lower allele frequency  less chance of homozygous individuals
XXV. Heterozygote advantage: (sickle cell disease) Being heterozygous for sickle cell confers resistance to
Malaria. Greater reproductive success of heterozygous individuals compared to homozygotes; tends to
preserve variation in gene pools.
XXVI. Frequency dependent selection (scale eating fish) is the term given to an evolutionary process where the
fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population.
XXVII. Natural Selection can lead to highly adapted species, but not perfect organisms:
1. Selection can only edit existing variations
a. Natural selection only favors the fittest phenotypes among those currently in the population (which
may not be the best)
b. It cannot create new alleles
2. Evolution is limited by historical constraints
c. Only existing structures and variations are acted upon
d. Old structures may be put to new uses
3. Adaptations are often compromises
e. Seal flippers are good for swimming but not for running
4. Random chance, natural selection, and the environment interact.
XXVIII. Some Key Ideas:
Natural selection can only act on existing structures and functions  new uses are often compromises
Natural selection acts according to current environmental conditions
Evolution does not “anticipate” a need or have a goal or direction
Traits and diversity can be preserved in recessive alleles among diploid organisms.
Fitness = the ability to get your genes into the next generation (Survival, Mating Success, Number of Offspring)
Variation is the raw material of natural selection
Mutations are the ultimate source of variation.
4
XXIX. Micro & Macro evolution
a. microevolution – the gradual adaptation of a population to its environment
b. involves changes in allele frequency in a population (changes in the gene pool)
c. can be observed over relatively short time periods
Macroevolution – evolutionary change on a large scale (new species, families, etc)
a. origin of new species and higher taxonomic groups
b. (usually) only observable in the fossil record
c. major source of biodiversity
XXX. What is a species?
biological species concept: "species are groups of interbreeding natural populations that are reproductively isolated
from other such groups."
a. Able to reproduce and give birth to fertile offspring
b. morphological species concept: Classification based on observable and measurable phenotypic traits
c. ecological species concept: views species in terms of their ecological niches and unique adaptations
d. phylogenetic species concept: Based on (assumed) common ancestry and genetics
XXXI. Reproductive barriers: feature of the organisms themselves which prevent interbreeding between populations,
even if their ranges overlap.
prezygotic barriers = prevent mating or fertilization between members of closely related species.
Examples:
a. Habitat (ecological) Isolation: Wrong place, right time = Populations occupy different habitats (niches) within the
same general area. Example: 2 species of garter snakes (Thamnophis) one is a water species the other a terrestrial
species example: parasites living in the same region but that live on different hosts are unlikely to encounter each
other).
b. Temporal Isolation: Right place, wrong time = Species that mate at different times of the day, or in different seasons,
or in different years will not interbreed; some species are nocturnal and others are diurnal. Example: Eastern Spotted
Skunk and Western Spotted Skunk
c. Behavioral Isolation: Right place & time; wrong outfit
There is little or no sexual attraction between males and females of different species; Examples: Bird / insect songs are
different; Firefly flash patterns are different; Different courtship rituals Lack of “mate recognition” Tends to evolve
more rapidly than other types of barriers
d. Mechanical isolation: Right place & time, wrong equipment Male and female sex organs are not compatible.
Examples: Certain insect species; snails (left-handed & right-handed shells) Some flowers can only be pollinated by a
particular bird, insect or bat species. Because the snails’ shells spiral in opposite directions, their genital openings
(indicated by the arrows) cannot be aligned and mating cannot occur.
e. Gametic isolation: Right time & place, wrong ingredients Specific chemistry of female reproductive tract may be
lethal to sperm of other species. Specific molecules on egg & sperm attach to each other. Example: The gametes of the
red and purple sea urchins are unable to fuse because their surface proteins do not match.
Postzygotic barriers = prevent hybrids from surviving or thriving; hybrids may be sterile. They prevent accidents of nature.
5
Horses and Donkeys  Mule or Hinny. (fertile) Hybrid breakdown: no viable offspring after first generation.
1. Reduced hybrid viability
2. Reduced hybrid fertility
XXXII. Reproductive isolation is necessary for speciation. In general there must be a restriction of gene flow between two subpopulations and the two populations must be subjected to different selective pressures and or genetic drift.
*** Selective pressure is any phenomena which alters the behavior and fitness of living organisms within a given
environment. It is the driving force of evolution and natural selection, and it can be divided into two types of pressure:
biotic or abiotic. Biotic pressure affecting an organism are living organisms within the same ecosystem that interact with the
affected organism. Abiotic pressure is created by non-living factors within the organism's environment, such as light, wind, and
soil.
XXXII. Allopatric speciation: The formation of a new species as a result of an ancestral population’s geographic isolation
(lack of gene flow) Allopatric speciation has occurred if: the populations have changed to such an extent that they
can no longer interbreed and produce viable offspring even if brought back together
*** Speciation is more likely if a sub-population is small and isolated, and exposed to different environmental pressures.
•
Sympatric speciation: A small population becomes a new species without geographic separation. (nonrandom mating
chromosomal changes). Sympatric speciation means that one population of one species became two species while in
the same geographic region with no physical separation
•
•
Allopatric: new species form while geographically isolated from parent population
– isolated populations evolve by natural selection, genetic drift, and accumulation of unique mutations
– reproductive barriers may arise as a result of genetic change
Sympatric: requires the emergence of a reproductive barrier that isolates a subset of the population
– allopolyploidy (hybridization between closely related species coupled with errors during meiosis
leading to fertile polyploid individuals) is common in plants
– change in habitat (apple maggots)
– sexual selection (mate choice)
– In both cases there must be a restriction of gene flow between populations and the emergence of
reproductive barriers in order for speciation to occur
XXXIII. Adaptive radiation = The evolution of many species from a common ancestor. Адаптивная
радиация — адаптация родственных групп организмов к систематическим нерезким однонаправленным
изменениям условий окружающей среды. Typically occurs when a small group migrates to a new (uncolonized)
area or when ecological niches become available due to extinctions. Allopatric and Sympatric speciation leads to
increased diversity
XXXIII. Hybrid Zones – Areas of overlap between populations of different (but closely related) species where hybrids
are formed.
1. Reinforcement = Hybrids are less fit than members of either parent species.
2. Stability = In spite of gene flow, each species maintains its own integrity
6
3. Fusion = Gene flow breaks down isolation of separate species
XXXIV. Living fossils = species once thought to be extinct for millions of years have been found still living on earth
XXXV. A ring species = is a situation in which two populations which do not interbreed are living in the same region and
connected by a geographic ring of populations that can interbreed.
XXXVI. Speciation is most likely to occur when:
small subset of population becomes isolated
Separated populations experience different selective pressures
Rapid change in da environment
Little or no gene flow between populations ( f.e. due to geographic barrier)
XXXVII. Adaptation-A biological adaptation is an anatomical structure, physiological process or behavioral trait of an
organism that has evolved over a period of time by the process of natural selection such that it increases the
expected long-term reproductive success of the organism.
i.e. giraffes evolving longer necks to reach tree leaves
exaptation-term coined by steven jay gould, an evolutionary process in which a given adaptation is first naturally
selected for, and subsequently used by the organism for something other than its original, intended purpose
i.e. evolving wings which would be useful for body temperature control, but useless for flying(they're too small)
until they evolved larger.
XXXVIII. Half life A specimen started with 100 g of radioisotope “X”
It now has 12.5 g of “X” left
The half-life of “X” = 1 million years
How old is the specimen?
1st half-life (100g  50g)
2nd half-life (50g  25g) 3rd half-life (25g  12.5g) 3 million years old
XXXIX. Continental drift has impacted the development of life on earth. Today the results are: mountain formation,
volcanoes, earthquakes, tsunamis. Volcanoes and Earthquakes are most common where plates meet. Europe and
North America are drifting apart at ~ 2 cm per year
XL.
The fossil record indicates five mass extinctions in the past 540 million years loss of habitat. Mass extinctions can
result in an increase in diversity, however, it may take millions of years to recover the levels of diversity found
before the extinction event.
a. new predators, parasites, competition
b. rapid change in the environment
c. catastrophic event on global scale
XLI. Heterochrony – (an evolutionary change in the rate or timing of development events) => allometric growth
XLII. Paedomorphosis: The retention in the adult of body structures that were juvenile features in ancestral forms.
явление, наблюдаемое у некоторых членистоногих, червей, земноводных, а также у многих растений, при
котором достижение половозрелости и окончание онтогенеза происходит на ранних стадиях развития,
например, на личиночной стадии. При этом особь может достигать взрослой стадии или не достигать её.
XLIII. Convergent evolution = Organisms that are not closely related can develop similar appearances and structures due
to similar environmental conditions and selective pressures. Example: Koalas of Australasia have evolved
fingerprints, indistinguishable from those of humans. Конвергентная эволюция эволюционный процесс,
при котором возникает сходство между организмами различных систематических групп,
обитающих в сходных условиях, то есть относящихся к одной экологической гильдии.
7
IX.
X.
XI.
XII.
XIII.
XIV.
XV.
Homology ( similarities due to common ancestry) ne ravno analogies ( similarities due to convergence = arising
from a common function)
Phylogenetic systematics = seeks to reconstruct evolutionary history and studies the patterns of relationships
among organisms
Phylogenetic trees depict = hypothesized evolutionary relationships among related organisms.
Domain => Kingdom = > phylum=> Class => order => family=> genus => species
Modern classification attempts to group species according to their phylogenic history, and seeks to properly place
them on tree of life. This is based on the assumption that all life comes from a common ancestor.
Organisms are placed into groups called clades based on inferred common ancestry. PRPER CLADES SHOULD
BE MONOPHELYTIC. Cladogram is constructed by identifying shared ancestral traits and shared derived
traits. Monophyletic groups consist of a common ancestor and all descendent groups.
In order to build molecular clocks we have to know how fast mutations tend to occur or how often changes to
DNA occur within a certain area of the genome. Molecular clocks are calibrated from known points of species
divergence in da fossil record.
XVI. Горизонтальный перенос генов (ГПГ) — процесс, в котором организм передаёт генетический
материал другому организму, не являющемуся его потомком. В отличие от горизонтального, о
вертикальном переносе генов говорят, если организм получает генетический материал от своего
предка. В области интересов генетики основное место занимает вертикальный перенос генов.
Однако в настоящее время горизонтальному переносу уделяется всё больше внимания.
XVII.
XVIII. The earliest primates likely arose ~ 65 million years ago and were probably small and arboreal.
Currently there are ~363 species of primates
XIX. Primates (order)Anthropoids
Monkeys (old world, new world)
not a monophyletic group
Hominoids = (Apes)
Hominins (old term = Hominids) = (Humans and extinct species which are closer to Homo sapiens
than they are to chimpanzees)
8
XX.
Bipedalism arose before large brain size, tool making and language.
Human evolution was not a smooth, linear process, there were many dead ends and side branches along
the way.
XXI.
How do we differ? uniquely human traits:
1. Bipedalism 2. Shorter jaws, reduced jaw muscles 3. Flatter faces 4. Larger brains . 5.
Complex, symbolic language6. Use of complex tools 7. Uniquely human traits 8. Long-term pair
bonding between mates 9. much longer period of parental care 10. Reduced body hair
XXII. Neanderthals & Humans
WE arose from common ancestor; but they were separate lineages. Humans are not direct descendants,
instead we are “sister species”. Neanderthals appeared first. But modern humans and Neanderthals
occupied Europe at the same time for at least several thousand years. The oldest human ancestors were
found in Africa.
XXIII. Homo habilis= “The handy man”= first toolmaker = 510 to 690 cc brain = Live ~ 2.4 to 1.6 mya
=possibly arboreal
XXIV. Homo ergaster= “working man” = More sophisticated stone tools = Similar body proportions to
modern humans = Well adapted to long distance walking, not aboreal.
XXV. Homo erectus = “upright man” = First Hominins to leave Africa = Culture is main reason H.
erectus was so successful
XXVI. Homo neanderthalensis = massive brain = later remains show decrease in robustness of the front teeth
and face, suggesting use of tools replaced teeth = Burial – Some evidence of purposeful burial and ritual
XXVII.
XXVIII.
9
10