Transcript Unit 9 Exam Review

What is a scientific theory?
– It makes falsifiable predictions with consistent accuracy across a
broad area of scientific inquiry
– It is well-supported by many independent strands of evidence,
rather than a single foundation
– It is consistent with pre-existing theories and other experimental
results
– It can be adapted and modified to account for new evidence as it
is discovered, thus increasing its predictive capability over time.
– It is among the most parsimonious explanations, sparing in
proposed entities or explanations.
Review
• Macroevolution –
If the changes are over a very long time and are large
enough that the population is no longer able to breed
with other populations of the original species, it is
considered a different species.
• Microevolution –
changes to the varieties of individuals in a population
such as a change in a species' coloring or size.
• Gene Pool –
all genes in a population
• Mutation –
– random change in structure of DNA. Every so often, a
mutation is beneficial for survival.
Review
• Natural Selection –
a) Genetic variability in a trait within population
b) Trait is heritable
c) Differential reproduction – must enable
individuals with the trait to leave more
offspring than others without the trait.
Review
• Sexual Dimorphism:
– The males & the females of a species have a
noticeable physical difference
Review
• Speciation –
– The formation of a new species from an ancestral
species
• Geographic Isolation –
– Species are unable to mate/blend their genes due
to the location(s) of species within a
habitat/globally
• Reproductive Isolation –
– Behavioral or physiological barriers that prevent
the reproduction between species.
Review
• Background Extinction –
– A slow rate of die off, often due to natural
selection
• Mass Extinction –
– A quick & massive die off of an entire population
or many populations
• Adaptive Radiation –
– after mass extinctions, numerous new species
evolve to fill vacated niches. Takes 1-10 million
years for adaptive radiation to rebuild biodiversity.
Review
• Artificial Selection –
– artificially selecting superior genetic traits
– Agriculture, Hatcheries, Pets
• Genetic Engineering –
• Gene splicing
• Species creation in laboratories
• Takes less time than artificial selection
• Age of the Earth –
– 4.57 billion years old
Review
• Eon  Era  Period  Epoch
• Cambrian Period –
– Sudden appearance in the fossil record of
many new phyla (Cambrian explosion)
– Abundant marine invertebrates
• Ordovician Period –
– Earliest vertebrates appeared
(ostracoderms)
– The first plants invaded land
Review
• Silurian Period –
– Coral reefs became abundant
– First jawed fish appeared (Placoderms)
• Devonian Period –
–
First fish evolved into tetrapods and invaded
land
–
Cartilaginous fish (sharks) became dominant
• Carboniferous Period –
– The first reptiles evolved from amphibians
Review
• Permian Period –
– Reptiles thrived and began their radiation
– Ended with the largest extinction event on
record – 96% of animal species disappeared
• Triassic Period –
– Reptiles returned to the seas
– Beginning of the radiation of dinosaurs
• Jurassic Period –
– Warm climate and high sea levels
– First small mammals appeared
– First evidence of feathered birds (Archaeopteryx)
Review
• Cretaceous Period –
– Mammals evolved into three forms
(monotreme, marsupial, placental)
– all dinosaurs and all ammonites, along with
many other species, became extinct
• Tertiary Period –
– primitive apes; first elephants
– First ancient hominids arose
Review
• Quaternary Period –
– Pleistocene: modern humans evolved; ended
with the Ice Age that saw the extinction of
mammoths and other animals
– Holocene: human civilization spread
throughout the globe and humans became the
dominant form of life
Review
• Tiktaalik roseae – important transitional fossil
discovered in 2005 that connects aquatic
species to terrestrial species
Review
• Changes in the skull of tetrapods:
– Skull becomes flattened
– Eyes move from the side of the head to the top
and to the front
– Pectoral girdle (bones around the neck) are
reduced so that the head can turn
– Snouts/jaws become elongated
– Primary palate expands
Review
• Terrestrialization (33 & 34):
– Bones become more dense to support weight
without the buoyant force of water
– Fin rays become digits
– organization of myomeres (striated muscles) in
fishes (locomotion)
– Lungs & pump (diaphragm, buccal pump, etc.)
– Thickening of dermis
– Body temperature control
Review
• Aquatic Mammal Examples:
– Cetaceans, Sirenias, Pinnipeds
• Aquatic/Terrestrial Mammal Similarities:
– Endotherms
– Placental (belly buttons)
– Mothers produce milk
– Most have hair at some stage of their
development
Review
• Aquatic/Terrestrial Mammal Differences:
– Modified limbs into flippers
– Some have reduced pelvises & femurs
– Cetaceans have flukes
– Cetaceans have nostrils located on the dorsal
portion of their head (blowhole)
Review
• Vestigial Features:
– Genetically determined structures that have lost
their ancestral function
– Examples:
• Femur bones & reduced pelvises in dolphins & whales
• Olfactory nodes found in the brains of most cetaceans
• Homologous bone structure
• Atavism:
– Reverting (genetic error of expression) to an
ancestral type
– Examples: Dolphin legs, human tails, chicken teeth
Review
• Conditions that favor fossilization –
– Having Hard parts – shells, bones, cysts
– Get buried, trapped
• Marine species
• Marsh, flooding areas
– Abundant species (with many individuals)
– Long lived species (as a species)
– Avoid eroding away
Review
• Homologous Structures –
– Similarities in body structures due to common
ancestry
• Analogous Structures –
– Structures with similar function that do NOT share
common ancestry
Review
• Population Genetics –
– The study of genetic changes in populations over time
– Quantify molecular differences within and among
populations
• Traits exhibit variation
• Gene Flow –
– The loss or gain of alleles (genes) in a population
due to migration of fertile individuals or gametes
between populations
a)Immigration
b) Emmigration
Review
• Genetic Drift –
– a change in allele frequency due to random chance
– Affect small populations
– Limits alleles available to subsequent generations
• Founder Effect –
– Genetic drift attributed to colonization by a limited
number of individuals from a parent population
• Bottleneck Effect –
• Genetic drift resulting from the reduction of a population, typically
• by natural disaster, surviving population does not represent the
original
• population’s gene pool
Review
• Directional Selection –
– 1 extreme is favorable
• Diversifying Selection –
– 2 extremes favorable
• Stabilizing Selection –
– Intermediate favored
Review
• Pre-zygotic Barriers –
– prevent successful fertilization between species
• Post-zygotic Barriers –
– allow fertilization but prevent successful
development / reproduction of hybrid.
Review
• Habitat Isolation –
– Two organisms that use different habitats even in
the same geographic area are unlikely to
encounter each other to even attempt mating.
• Behavioral Isolation –
– Many species use elaborate behaviors unique to
that species to attract mates.
• Temporal Isolation –
– Two species that breed during different times of
day, different seasons, or different years cannot
mix gametes.
Review
• Mechanical Isolation –
– Physical/ structural mechanism that prevents
reproduction
• Reduced Hybrid Viability –
– Miscarriage, early death
Review
• Reduced Hybrid Fertility –
– Sterile
– Unattractive to opposite sex
• Hybrid Breakdown –
– 1st generation is viable & fertile
– 2nd generation is unviable or infertile
– Occurs in plants
• Allopathic Speciation –
– A mode of speciation induced when the ancestral
population becomes segregated by a geographic
barrier
Review
• Parapatric Speciation –
– Takes place in large range
– Variable environmental
– Variable selection pressure
– Non-random mating
• Sympatric Speciation –
–
–
–
–
Takes place within habitat of parent species
Reproductive barrier forms within a subset of population
Maybe genetic that immediately blocks reproduction
Maybe behavioral
Review
Review
• Phylogeny –
– Technique to understand evolutionary
relationships
• Phylogenetic Trees –
Review
• Convergent Evolution –
– Evolutionary pattern where two or more non
related taxonomical groups independently evolved
same/similar characteristics
– Similar structures evolve under similar
environmental conditions