Comparative Anatomy Studies in Vertebrate Structure

Introductory Concepts Evolution Kinds of Chordates Developmental Processes

What should we know about anatomy –Parts –Names –Developmental Origins –Functions

Introductory Concepts Evolution Kinds of Chordates Developmental Processes

Comparative - why comparative? –Logical progression, learn in steps –Comprehensive, know all vertebrates easily –Broadens our frame of biological knowledge Phylogeny Evolution Embryology Physiological ecology

What is a chordate? –In respect to other animals –3 germ layers (not a sponge) –Bilateral symmetry (not a cnidarian) –Tube gut (not a flatworm) –Eucoelomate (not a round worm) –Deuterostome (not mollusk, annelid, or arthropod) –Segmented (not an echinoderm) –Unique features of chordates –Pharyngeal gill slits –Notochord –dorsal nerve chord

–What are the chordate subphyla? Urochordata - tunicates Cephalochordata – amphioxus Craniata (formerly vertebrata) »Hagfish »Lamprey »Cartilagenous fish »Bony fish »Amphibians »Reptiles »Birds »mammals

Phylogeny – “family tree” of taxa Ontogeny - developmental process Von Baer’s Law –“features common to all members of major phylogenetic group of animals develop earlier in ontogeny than do features that distinguish subdivisions of the group” –(shared features develop earlier)

Conserved traits – shared by all or most subgroups of a taxon and assumed to be passed down from one ancestral line Derived traits – present within a subgroup of a taxon as a new trait which differentiates that subgroup from others.

The hierarchial system of taxonomy –Kingdom –Phylum –Class –Order –Family –Genus –Species

Problems with the hierarchial system –Discrete levels oversimplify the phylogeny –Arbitrary placement of taxonomic levels –Backward jumps in taxonomic level names –Standards for classification are not the same in all groups

Problems with the species concept –Discerning the viability of hybrids –Populations mix in some areas, but not others –Ring species –Checking for reproductive separation of allopatrics –Clones and parthenogens –Polyploid species

Lumpers and Splitters

EVOLUTION a controversial subject –Diversity of viewpoints Literal Genesis, deny evolution Literal Genesis, accept natural selection Figurative Genesis, God directs evolution Figurative Genesis, God initiated universe Deny God as a factor in the natural world

Levels of scientific certainty Hypothesis > Law Theory Law – supported by all experimentation, and all alternatives disproven by experimentation

Five tiers of evolutionary concept –Development of first life form –Microevolution –Natural Selection –Speciation –Macroevolution

Development of first life form –Cooling of Earth allows molecule formation and development of an atmosphere with methane, water, ammonia, hydrogen, and nitrogen –Further condensation forms organic molecules –Accumulation of organic “soup” –Organic macromolecules (preorganelles) –First reproducing cell

Microevolution –Replication and cell division errors result in genetic variants in a population –Not all members of a population will have the same genomes

Natural Selection (survival of the fittest) –Because not all members of a population have the same genetic make up, some may have a survival advantage. –Evidences Peppered moth Pesticide resistance Galapagos finches

Speciation – the isolation of a reproducing lineage from other lineages within the taxon The allopatric speciation concept –Geographic separation –Genetic change –Reproductive isolation Sympatric speciation