GEOL20230

• Tullimonstrum (Tully Monster) eye structure


  - transverse bar with eyes

  - dark spot (4) hasoblateandcylindricalmelanosomes in specific layers

  - combo and arrangement unique tovertebrates(debated)
• What are melanosomes and the types

  - pigment granules

  - oblate and cylindrical

  - associated with Tullimonstrum (Tully Monster)
• Biological species concept


  - Species is a population or group of populations whose members have the potential to produce fertile offspring

  - overall cohesion maintained but can have variation in different environments (ecophenotypic variation)
• Morphological species concept


  - characterizes a species by body shape and other structural features/ anatomy
• Issues with Morphological Species Concept?

  - gaps exist in fossil record and make it hard

  - small sample size
• sympatric speciation


  The formation of new species in populations that live in thesame geographic area

  (through isolation)
• allopatric speciation (and types)

  - The formation of new species in populations that are geographically isolated from one another (through geographic barrier)

  - symmetrical and asymmetrical
• symmetrical allopatric speciation


  - parent species divided roughly equally

  - two new species may arise
• asymmetrical allopatric speciation


  - a small peripheral population is isolated

  - parent species may continue unaltered while peripheral may evolve to new species (Founder Effect)
• Founder Effect


  - Rapid and unusual evolution in smaller population as gene pool is especially small

  - may be very different from original population genotypically and phenotypically
• Microevolution


  - changes inside apopulation

  - driven by variation in gene frequency among pop over time

  - via mutation, gene flow (migration), genetic drift, natural selection
• Macroevolution


  - changes at or above level ofspecies

  - appearance of novel structure

  - periods of stasis, character change over time, speciation (lineage splitting), and extinction (lineage termination)
• Alternative models for speciation and lineage evolution?

  phyletic gradualism and punctuated equilibrium
• Phyletic gradualism


  - most evolution within species lineages

  - slow, ongoing, progressive evolution

  - variation deviates on x-axis

  - anagenesis
• Anagenesis


  species formation without branching of the evolutionary line of descent.
• Punctuated equilibrium


  - choppy

  - fossil pops in stasis for long intervals of time (minimal evolution)

  - evolution concentrated in short-lived speciation events

  - variation does not deviate on x-axis

  - cladogenesis
• Cladogenesis


  species formation by evolutionary divergence/ branching from an ancestral form
• Taxonomy


  The study of identifying, describing, naming, and classifying organisms.
• Systematics


  Diversity and evolutionary relationships among groups
• Linneaus System


  - Kingdom, Phylum, Class, Order, Family, Genus, Species

  - very flexible system
• The basis for choosing taxonomy classification criteria?

  Phenetics vs cladistics
• Phenetics (numerical taxonomy)


  - based on the number of shared features to form taxa

  - statistically based + objective

  - includes characters and morphometrics (landmark analysis)

  - all morphological features treated equally
• How to do phenetics classification?

  - reduce features into OTUs - operational taxonomic units

  - assemble data matrix OTUs vs characters (until OTUs merge into one)

  - computer-based

  - result = branching diagram of similarity
• Cladistics


  - reflects evolutionary history (ignores phenetic similarity)

  - characters weighed differently

  - looks for synapomorphies (shared apomorphy)

  - nodes defined by synapomorphies

  - often a branching diagram
• apomorphy


  a derived trait
• synapomorphy


  - shared derived character by 2+ taxa/groups

  - defines a monophyletic group

  - presumed present in most recent ancestor
• autoapomorphy


  derived character unique to a taxon/group
• plesiomorphy


  ancestral character state for a particular clade
• sympleisomorphy


  shared ancestral trait by 2+ taxa (ie mammals and 4 limbs)
• homoplasy


  - A similar structure or molecular sequence that has evolved independently in two species

  - convergent evolution
• monophyletic group


  ALL descendants of a common ancestor

  
• paraphyletic group


  Does not include all descendants of common ancestor

  
• polyphyletic group


  Does not include common ancestor

  
• Total group


  stem + crown group
• Crown group


  - Last common ancestor of all living forms and descendants

  - extinct and extant
• Stem group


  - Remainder of clade outside the stem group

  - All extinct

  - Good for learning about the acquisition of characters
• molecular systematics


  A scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships.
• the 2 molecular systematics methods?

  DNA-DNA hybridization and DNA sequencing
• DNA-DNA hybridization procedure


  - boil solution of DNA in 100 ºC water

  - 2 strands separate

  - upon cooling, strands will recombine

  - BUT if a solution has mix of DNA from 2 organisms some from each combine (= hybrid)

  - when reheated, strands separate but DNA strands from 2 less closely related orgs do so at lower temps
• DNA sequencing


  - Determining the exact order of the base pairs in a segment of DNA

  - PCR amplification method