MISCONCEPTIONS INVERTEBRATE ZOOLOGY NATURAL SELECTION SELECTION CHAPTER 1,2: NATURAL SELECTION, EVOLUTION, CLADISTICS. these are not true!

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1 THE BASIS OF EVOLUTION NATURAL SELECTION CHAPTER,: NATURAL SELECTION, EVOLUTION, CLADISTICS INVERTEBRATE ZOOLOGY Darwin's majr theries (Mayr 985) perpetual change cmmn descent multiplicatin f species gradualism natural selectin THE BASIS OF EVOLUTION SELECTION law f natural selectin survival f the fittest? scial darwinism What is fitness? Darwinian fitness inclusive fitness relative fitness requirements fr natural selectin (imprtant) reprductin variatin heritability differential mrtality / fecundity COMMON MISCONCEPTIONS ABOUT EVOLUTION AND SELECTION THE IDEA THAT THE ENVIRONMENT ITSELF CAUSES CHANGES TO OCCUR OVER TIME GENETIC VARIATION IS NOT IMPORTANT? EVOLUTION VIEWED AS GRADUAL CHANGES IN TRAITS EVOLUTION IS OVER. DIRECTIONALITY OF EVOLUTION... THE IDEA THAT EVOLUTION HAS A GOAL, OR IS GOING SOMEWHERE... MAN EVOLVED FROM MONKEYS OR GORILLAS OR CHIMPS. these are nt true! MISCONCEPTIONS

2 TALKING ABOUT PHYLOGENIES TERMINOLOGY TO AVOID avid using terms that impse value n taxa mre evlved, highly evlved less evlved advanced higher WHY STUDY INVERTEBRATES? INVERTEBRATES Invertebrates by far represent mst f the species f animals great diversity in many ways, the mst successful grups f rganisms are invertebrates inverts tell us much abut the wrld arund us THESE TERMS HAVE NO REAL MEANING! A LITTLE BACKGROUND PATTERNS OF DIVERSITY Althugh Evlutin is nt directinal - evlutinary trends themes in bdy plan repeated patterns SURFACE AREA TO VOLUME RATIO CONSTRAINTS ON FORM 5 Surface area increases while ttal vlume remains cnstant Ttal surface area [Sum f the surface areas (height width) f all bxes sides number f bxes] Ttal vlume [height width length number f bxes] 5 5 Surface-t-vlume (S-t-V) rati [surface area vlume] 6. 6

3 Muth Exchange Gastrvascular cavity Exchange Exchange Nutrients Digestive External envirnment Muth Fd Animal bdy Bld Heart CO O Circulatry Respiratry Cells Interstitial fluid EVOLUTIONARY TRENDS BODY PLANS develpmental patterns diplblasty triplblasty bdy cavity -- celms acelmate pseudcelmate eucelmate Celmate Pseudcelmate Celm Digestive tract (frm endderm) Pseudcelm Digestive tract (frm endderm) Bdy cvering (frm ectderm) Bdy cvering (frm ectderm) Tissue layer lining celm and suspending internal rgans (frm mesderm) Muscle layer (frm mesderm) Excretry Acelmate Bdy cvering (frm ectderm) Tissuefilled regin (frm mesderm) Anus Unabsrbed matter (feces) Metablic waste prducts (nitrgenus waste) Wall f digestive cavity (frm endderm) DEVELOPMENTAL PATTERNS BODY PLANS prtstmes spiral cleavage schizcely prtstmus determinate cleavage deuterstmes radial cleavage entercely deuterstmus indeterminate cleavage SPIRAL RADIAL

4 EVOLUTIONARY TRENDS SEGMENTATION metamerism prbably evlved 3 times panarthrpda chrdata annelida advantages: efficient lcmtin tagmatizatin redundancy EVOLUTIONARY TRENDS SYMMETRY radial symmetry biradial pentaradial bilateral symmetry RADIAL SYMMETRY BILATERAL SYMMETRY hmlgy f the radius in vertebrates ADAPTATIONS? ANALOGY (HOMOPLASY) HOMOLOGY CONVERGENCE human cat whale bat

5 MAKING SENSE OF TREES SYSTEMATICS embry develpment turtle chicken hrse human example tree: lphtrchza Bilateria ecdysza recapitulatin -- ntgeny recapitulates phylgeny atics -- phenetics cladistics (primitive vs. derived) synapmrphies - autapmrphies - synplesimrphies - CLADOGRAM OR PHENOGRAM OR TREE (DENDROGRAM) CLADISTICS cnidaria mllusca annelida nemata arthrpda metamerism spiral cleavage bilateral symmetry ecdysis jinted appendages metamerism O A CB BC D E O EA D B C C B D E A NODES CAN PIVOT. SAME TREE TREES NODES CAN PIVOT. SAME TREE TREES

6 chelicerata myriapda xencarida PHYLOGENETIC TREES ARE USED TO CREATE TAXONOMIC UNITS... (TAXA, TAXON, GENUS, PL. GENERA) MONOPHYLETIC-- PARAPHYLETIC! entgnatha insecta cpepda malacstraca thecstraca HEXAPODA CRUSTACEA PANCRUSTACEA POLYPHYLETIC -- branchipda PARAPHYLETIC -- TAXA / GROUPS PHYLOGENY OF SELECTED ARTHROPODS (REGIER, ET AL., 00) tardigrada ichthystraca +pentstmida stracda SOME BASICS CLADISTIC ANALYSIS ways t cnstruct a tree Hennig argumentatin, Wagner ptimality parsimny - the simplest answer is prbably right - STEPS 3 5 steps utgrup A 0 B C 5 B 5 A 3 ABCC B A B A C B MORE PARSIMONIOUS A D C B steps B C D A E E PARSIMONY? steps utgru p A B C D E WHAT IF YOU END UP WITH TREES? 3 3 AB 000 steps

7 HOW DO WE KNOW IF A TREE IS A GOOD ONE? SUPPORTING TREES parsimny jackknifing btstrapping