WILD 3580 1st Edition Lecture 8Outline of Last Lecture I. Trends in Evolutionary ChangeII. Speciation MechanismsOutline of Current Lecture I. Geologic ErasII. FishIII. Fish FormsIV. Fish Evolution and ClassificationV. Ostracoderm Characteristics VI. Superclass: Gnathostomata Current LectureI. Geologic Eras- Geologic deposits give us a measurement of time - Relative age of fossils (the deeper the organisms are found, the older it is)- Eras are divided into periods, which are subdivided into epochs o Age of Fishes- Devonian Period of the Paleozoic Era II. Fish- The first vertebrates - Aquatic vertebrates that have fins(limbs) and gills some exceptions- 28,000 living species (high in diversity) make up about half of all vertebrates o Been around the longest o 70% of Earth is water o Can adapt quickly - 58% marine, 41% freshwater, 1% diadromous: move between salt and fresh water as a part of their normal life cycleIII. Fish Forms 1. Anadromous- spend most of their lives in the ocean but return to freshwater to reproduce (Ex. Salmon)a. Semelparous- reproduce once during life These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Iteroparous- reproduce multiple times during life 2. Catadromous- spend most of their lives in freshwater and return to the ocean to reproduce (Ex. Eels)3. Amphidromous- move between fresh and salt water during some part of life; not for reproductiona. Feeding, overwinteringIV. Fish Evolution and Classification- Probably arose from the Lancelet or Amphioxus - Have a boney head shield- Historically called Ostracoderms= “shell-skinned”o 2 classes: Pteraspidomorphi ( ancestors to modern hagfish)and Cephalaspidomorphi (ancestors to modern lampreys)V. Ostracoderm Characteristics - Bony armor- Pineal organ: light sensing organ- Hypocercal tail - No paired fins or true jaws - Probably bottom dwellers and filter feeders VI. Superclass: Gnathostomata - Vertebrates with jaws - Arose independently, did not have a common ancestor with jawless fish- Consequences of having jaws:o Allows a greater diversity of foods o Defense against
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