Lecture 2 MARB 435 Outline of Last Lecture 1 Syllabus Introduction to Marine Invertebrate Zoology 2 Introduction of Invertebrate A Invertebrate Diversity B Pharmaceutical Role 3 Invertebrate Classification A Latin Binomials B Classification 4 Lecture 1 Vocabulary Outline of Current Lecture 1 Introduction to Phylogenetics A Morphological Data a Characters b Character States c Character Matrix B Molecular Data a Characters b Character States C Introduction to Phylogenetic Trees a Cladogram Trees b Phylograms Trees c Ultrametric Trees D Resolution a Polytomy b Multifurcation c Bifurcation E Lecture 1 Note Vocabulary Current Lecture Phylogenetics Phylogenetics is the study of evolutionary relatedness of taxa or species with common ancestors represented in a phylogenetic tree Phylogenetic trees share a common ancestor and its descendants The phylogentic trees have branching points that represent speciation events Phylogenetic trees are made using two types of data morphological or molecular data Morphological Data Morphological data is data that can be seen with or without microscopes Morphological data is broken down unto two factors character and character states Characters are individual structures that can be compared among similar species Ex eyes or claws Character states are different versions of characters Ex blue eyes or brown eyes Ex scissor claws hooked claws or flat claws Character Matrix Is a table composed from morphological data an example is provided below Figure A Simple Character Matrix Basic The tables basic composures Figure B Character Matrix Complex The tables more complex formation Figure A Species Eye Claw A Blue Scissor B Brow Hooked C Brown Flat NOTE Characters across the top of the table and character states go vertically under each category Figure B 1 2 A 0 0 B 1 1 C 1 2 NOTE Now the characters and character states are represented by numbers The numbers represent the words in Figure A The characters across the top are represented by numbers instead of words The character states going vertically under the characters also represented by numbers For eyes blue is represented by 0 and brown is represented by 1 For claws scissor is represented by 0 and hooked is represented by 1 and flat is represented by 2 Molecular Data Molecular Data is mainly nucleotides and DNA A nucleotide is a chain of coded DNA such as ACGT In molecular data the character is the nucleotide and the character states are ACGT which are complied in a table such as morphological data However when dealing with molecular data the table sizes are much larger and can t be calculated manually usually which is why information like this may be programmed into a computer system program to composed the Character Matrix table Tree Types When dealing with phylogenetics a student must understand the three types of trees 1 Cladograms These table types have no meaning and represent no scientific analysis 2 Phylograms These table types are used to represent genetic changes over a period of time 3 Ultrametric Theses trees represent change of time Resolution Resolution is the way phylogenetic trees are understood There are three main resolutions to understand polytomy multifurcation and bifurcation 1 Polytomy They is commonly seen as a star and no data or analysis can be completed when there is polytomy in a phylogenetic tree 2 Multifurcation This reveal some clarification for phylogenetic trees and are a little more broken down the polytomy but doesn t completely show the evolution of a species 3 Bifurcation These are fully resolved phylogenetic trees where the reader can comprehend and see the evolution of an animal over a period of time Important Vocabulary 1 Autamorphy A categorization one taxon by a particular characteristic For example Cocker Spaniels and Great Danes are both dogs and are in the same species However Cocker Spaniels have curly ears making the curly ear gene in Cocker Spaniels an autamorphy because Great Danes don t have curly ears Autamorphy doesn t help with phylogenetic analysis because you ve got nothing to compare it too Each taxon usually has one autamorphy but it isn t used when composing a phylogenetic tree 2 Synapomorphy Is a character state that is shared by all the members of one groups These are highly helpful when making Phylogenetic trees 3 Paraphyletic groups Are Phylogenetic trees that don t include all descendants of an ancestral species 4 Exopthalmia A group of species that includes all descendants of a common ancestor 5 Sister Taxa Are two species that come from the same branching point on a phylogenetic tree 6 Polphyletic group Animals with no direct common ancestor For example birds bats and insects are all flying animals but they don t share a common ancestor