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What is the slope of the mid parent and mid offspring regression?
h^2 (a.k.a narrow sense heritability)
Macroevolution
evolution above the species level
Microevlolution
evolution within populations
Macroevolution includes…
the origin, diversification, and the extinction of species
Two distinct phenomena
-Large scale evolutional change (ex: Major morphological change)
-Evolutionary process above species level
Macroevolution relies on
reconstruction of the past
i.e. paleontology, comparative phylogenetic studies, and evo-devo studies
Speciation
the divergence of lineages
lineages can…
further diversify into clades, and then these clades can be traced back to a speciation event
Stasis
a timeperiod when little to no evolution change is occuring in a lineage
When Stasis ends it can end suddenly with
cladogenesis
Gradualism in a evolutional sense
evolution occurs bit by bit in a lineage (anagenesis)
Anagenesis
type of evolution in which a species gradually changes over time, eventually becoming a new and distinct species. It involves the accumulation of small genetic changes over a long period of time, rather than the branching of one species into two or more distinct species.
Extinction (4 different definitions)
When a species dies out
When reproduction in nature is not longer able to occur
Death of last individual
disappearance from the fossil record (though the record is incomplete)
How many mass extinctions have occured (number discussed in class)
5
Species Concept
The species concept is a fundamental idea in biology that defines what constitutes a species. It is a way of categorizing organisms based on their shared characteristics and evolutionary history. There are several different species concepts, including the biological species concept, morphological species concept, and phylogenetic species concept. Each concept has its own criteria for defining a species, but all aim to capture the essential features that make a group of organisms distinct from others.
Why are species concepts important
for clear communication
What are the different species concepts
Morphological Species (Morphospecies) concept
Biological Species Concept
Phylogenetic Species Concept
General Linkage Concept
What is Morphospecies based on?
Phylogenetics and based on expert opinion
What are the Pros and Cons of Morphospecies concept?
Pro: Widely applicable
Con: arbitrary, and the presence of cryptic species
What is Biological Species Concept based on?
Reproductive Isolation
What are the Pros and Cons of Biological Species Concept
Pro: confirms the lack of gene flow, and is testable
Con: can’t apply to asexual lineages/fossils/plant hybrids, difficult to apply in nonoverlapping locations
Phylogenetic Species Concept defines a species as:
the smallest possible monophyletic group, that is recognized by unique traits
this is useful for systematics
What are the Pros and Cons of Phylogenetic Species Concept
Pro: Applicable to most organisms, stat testable
Con: Data-intensive, can cause a large reorganization of taxa and species names
What is General Linkage Species concept definition of a species
a metapopulation that exchanges alleles to comprise the gene pool
What concept is best for fossils?
Morphospecies
What concept is best for bacteria
General Linkage Species Concept
What can differentiate bacterial species?
specific adaptations and observing a microbial mat
Which of these is the most likely sequence of events in allopatric speciation?
First, geographic separation; then, genetic divergence; finally, reproductive isolation
Penstemon (beardtongues) are wildflowers with a high degree of pollinator specificity. Suppose that two closely related populations of Penstemon have diverged in isolation, adapting to different species of bee pollinators. When the two populations come into secondary contact, hybrids have flowers that aren't efficiently pollinated by either species of bee and therefore have lower fitness than either parent. What is the likely outcome?
Reinforcement
What best describes Allopolyploidy:
-It Results from interspecific hybridization
-Is common in plants
-It Can generate new species in a single generation
-All of these
All of these
Speciation involves….
barriers to reproduction
Types of isolating barriers
Extrinsic and instrinsic
Extrinsic barriers
Geographic, landscape that prevents gene flow
Intrinsic Barriers
Reproductive, these are barriers when the populations are still with eachother
Allopatric Speciation
type of speciation that occurs when a population of a species is geographically separated from other populations and evolves independently, leading to the formation of a new species. This can happen due to physical barriers such as mountains, rivers, or oceans, or due to human activities such as deforestation or urbanization. Over time, genetic differences accumulate between the separated populations, eventually leading to reproductive isolation and the formation of distinct species.
Sympatric
process of speciation that occurs when two or more populations of a species live in the same geographic area and become reproductively isolated from each other, leading to the formation of new species without any physical barriers separating them. This can occur through various mechanisms such as polyploidy, hybridization, and disruptive selection.
Parapatric Speciation
speciation is a type of speciation where two populations of a species evolve into distinct species while sharing a common border. This occurs when there is limited gene flow between the two populations due to factors such as geographic barriers or differences in habitat. Over time, genetic differences accumulate and the two populations become reproductively isolated, leading to the formation of two distinct species.
Allopolyploid leads to….
extremely rapid speciation, because hybrids are able to mate
What are two patterns that explain the distribution of taxa
Dispersal and Vicariance
Dispersal
movement of population from 1 region to another with little to no return exchange
Vicariance
formation of a geographic barrier that divides a once whole population
Vicariance leaves a
distinct phylogenetic signature
Punctuated equilibria
periods of stasis punctuated by brief periods of rapid change
Few fossil series are complete enough to test between stasis and gradualism, what are the best?
Marine invertebrates
What is the mode of speciation?
Mode can vary for different traits within a lineage
What term did Dawkins use?
variable speedism
Adaptive Radiation
Rapid diversification of many species from few • Single or small group of ancestral species • Numerous descendent species • Wide variety of ecological niches
When does adaptive radiation occur?
when there is increased ecological opportunity
-abundant resources, extinction of competition, morphological innovations
Key innovations pave the way for
adaptive evolution
Background Extinction
the normal rate of extinction
Mass Extinction
a statistically significant increase above background extinction rates
Mass extinction main points
its a rapid event where anywhere from 20%-90% of species die
Affect organisms across…
phyla, habitats, and geography, and affect them all differently
Causes are typically _________
Extrinsic
What are the big 5
• Late Ordovician
• Late Devonian
• End-Permian
• End-Triassic
• K-Pg Boundary
Causes of the “Great Dying”
• Ultimate cause: Volcanism
• Evidence suggests that the Siberian Traps eruptions drove the end- Permian extinction event
What was the biggest of the big 5
End Permian
K-pg is thought to be due to….
big ateroids
-evidence: layer in earths surface with increased leves of Iridium (rare metal on earth, but is common in space rocks) and the crater in the Gulf of Mexico
After K-pg what type of organisms flourished?
Mammals
-birds, snakes,and frogs also survived
Aristotle
Scala naturae:
which ranked things by complexity
James Hutton
Gradualism
Alfred Russel Wallace
“Father of biogeography”
Plato
•Theory of Forms
•Deduction from principles
•Emphasis on the eternal and unchanging
Carl Linnaeus
was "the father of modern taxonomy",
Systema Naturae (1735), he used binomial nomenclature and homologies. Ranked in order of kindom,class, order, genus, and species.
Jean-Baptiste Lamarck
proposed the 1st cohesin theory of biological evolution. He determined thatenviromental conditions give rise to changes and he is remembered for the inheritance of aquired traits. Phylum and family were added later on.
Thomas Henry Huxley
Book: Evidence as to Man’s Place in Nature
Darwins most influential books
On the Origin of species by means of Natural selection
The Descent of man, and selection in relation to sex
Cuvier
•Pioneer of biostratigraphy
•Established the fact of extinction
•Catastrophism
•Fixity of species
Lyell
Uniformitarianism
Thomas Malthus
Book: An Essay on the Principle of Population (1798)
•Left unchecked, human population growth will outpace resource availability
Ernst Haeckel
Neo-Lamarckism
Hennig
Was the Founder of phylogenetic systematics / cladistics
What are the 8 lines of evidence for evolution
Homology, Vestigial Traits, artificial selection, direct observation of microevolution, speciation, the fossil record, biogeography, and the age of the earth.
Homology
similarity due to the inheritance of traits from a common ancestor
Vestigial Traits
A special case of homology,
Inheritance of traits from ancestors explains cases of “poor design” and vestigial or “leftover” traits
Artificial Selection
Direct Observation of Microevolution
Moth coloration patterns in polluted/ashy areas
Speciation
the formation of new and distinct species in the course of evolution.
How The Fossil Record proves
•Extant life forms resemble forms found in the fossil record •Transitional fossil forms •Macroevolution •The fact of extinction
Biogeography
•Law of Succession
•Distributions of living species
•Fairly sharp barriers that match for many taxa: biogeographic regions
What are the 3 definitions of evolution?
Broadest sense: change over time
Darwin’s definition: descent with modification
Genetic definition: change in allele frequencies over time
What are the 4 alternatives to natural selection:
Theistic evolution
Neo-Lamarckism
Orthogenesis
Saltation / Mutationism
Theistic Evolution
view that God acts and creates through laws of nature.
Asa Gray
Neo-Lamarckism
theory of evolution that suggests that acquired traits can be passed down to offspring. This theory is an extension of Lamarckism, which proposes that organisms can pass on traits that they acquired during their lifetime to their offspring. However, Neo-Lamarckism also incorporates the idea of genetic inheritance, which was not part of Lamarck's original theory.
Orthogenesis
suggests that evolution is directed towards a predetermined goal or endpoint.
Saltation / Mutationism
no selection, evolution by mutational drive
What are the 2 sources of homoplasy
convergence and reversals
4 Steps to inferring phylogenies
1.Collect data 2.Identify possible homologies 3.Tree reconstruction 4.Tree comparison
What are the 3 domains of life?
1.Archaea
2.Bacteria
3.Eukarya
4 Geological Eons
• Hadean
• Archean
• Proterozoic
• Phanerozoic
Hadean Eon 4.6-4 bya
Formation of the earth ~4.6 BYA
Liquid h2o 4.4 BYA
Plate tectonics 4 BYA
*Hellish conditions, high CO2 atmosphere
Archean Eon 4-2.5 BYA
Contenents, little free O2, LIFE BEGINS, FIRST FOSSILS (STROMATOLITES), PHOTOSYNTHESIS BEGINS 3.4 BYA
Oxygen Catastrophe 2.4-2 BYA
What were the 3 Geological Eras within the Phanerozoic Eon
• Paleozoic
• Mesozoic
• Cenozoic
What were the 6 geological Periods within the Paleozoic Era
• Cambrian
• Ordovician
• Silurian
• Devonian
• Carboniferous
• Permian
3 geological Periods within the Mesozoic Era
• Triassic
• Jurassic
• Cretaceous
3 geological Periods within the Cenozoic Era
• Paleogene • Neogene• Quaternary
2 geological Epochs within the Quaternary Period
• Paleocene
• Holocene
Analogy
similarity due to shared function
Biases in the fossil record
•Fossilization depends on many variables
•Durability of the tissue
•Burial timing and conditions
•Oxygen level
•Geographic bias
•Associated with ancient environments / habitats
•Lowland and marine environments dominate
•Taxonomic bias
•Marine organisms, bony/shelled organisms
•Temporal bias
•Old rocks are rare
Sir Francis Bacon
created the Scientific method, gives order to expirementing