Vertebrate Biology Chapter 1 Natural Selection Darwin s Four Postulates 1859 Darwin wrote the book On the Origin of Species by Means of Natural Selec tion which contained four main postulates Individuals within species vary Some of the variations found in the population are passes on to offspring Every generation more produced than can survive The survival and reproductive success of individuals is not random Phenotype all of the traits both physical and behavioral displayed by an organism Genotype genes passed from one generation to the next Fitness the degree to which an individual contributes to future generations Sexual Selection Direct competition between males for females The female does the choosing among many males Chapter 2 The Phylum Chordata Subphylum Vertebrate All vertebrates share 4 traits at some point in their life history Notochord Pharyngeal slits Dorsal hollow nerve chord Postanal tail Chapter 3 The Origin of Vertebrates Jawless Fish Agnathans First fossils identified as vertebrates belonged to a group of jawless fish classified as Agnathans These fish were given the general name ostracoderms The presence of bone is very significant in these fossils It is assumed that all fish had some type of ostracoderm as their ancestors Superclass Agnatha contain 5 classes 2 living 3 extinct including the extinct ostracoderms Class Myxini includes the living hagfishes a marine group of bottom feeding scavengers Have been evolving independently for 530 million years have changed very little First appeared in the fossil record during Ordovician period Class Cephalaspidomorphi first appeared in the fossil record in the Carbonifer ous period Includes lampreys Chapter 4 Jawed Fish Gnathostomata Superclass Gnathostomata Jawed Fish 3 major groups of living jawed fish Chondrichthyes cartilaginous fish skeletons are composed entirely of cartilage fertilization is internal first appeared in the fossil record during the Silurian period Sarcoptergyii lobe finned fish thought to be the direct ancestors of tetrapods 2 distinct fish are found in this group the lungfish coelacanths Actinoptergyii ray finned fish most familiar to us subclass Chondrostei considered primitive ray finned fish contains fish that thrived during the Devonian period subclass Neopoterygii advanced or modern ray finned fish contains the familiar fish we see and eat Chapter 5 Tetrapods Amphibians and Reptiles Class Amphibia Oldest known members appeared in Devonian period Oldest member was Ichthyostega All are extinct with the exception of the Subclass Lissamphibia frogs toads etc Traits bony skeletons four limbs tetrapods webbed feet many members use skin for gas exchange tied to water Chapter 6 Class Reptilia major lines of descent From the time they appeared in the fossil record reptiles evolved along three One line led to turtles One to mammals One to snakes lizards crocodiles alligators and birds Advantages of Amphibians Reptiles mammals and birds acquired extra embryonic membranes that surrounded the egg with fluid allowing them to be laid anywhere amniotes Thick skin prevents drying out so they could move into new environments Developed a neck allowing to expand field of vision Traits Scaly Clawed Ectothermic Respiration through lungs Eggs laid that protect full formed young 5 subclasses are usually recognized in the Class Reptilia Subclass Anapsida Turtles have distinctive shell and ability to retract head Subclass Lepidosauria Lizards and Snakes Subclass Euryapside extinct marine reptiles Subclass Archosauria Birds Considered ancestor to crocodiles alligators caimans and birds includes dinosaurs and extinct pterosaurs Subclass Synapside Mammals includes many extinct forms and is the ancestor to the mammals Chapter 7 Birds and Mammals Class Aves Birds outnumber all vertebrates except fish Found in all environments are seed eaters insect eaters and effective preda tors or larger species Derived from a bipedal Archosaurian reptile Closely related to crocodiles have very similar bone and muscle structure Specialized features Endothermy warm blooded animals ability to maintain constant body tem perature Subclass Archaeornithes Extinct birds contains earliest vertebrates classified as birds Subclass Neornithes All other birds tremendous diversity Class Mammalia 3 Major Groups Including Subclass Prototheria egg laying represented by platypuses and Echidna Subclass Theria includes Infraclass Matatheria represented by marsupials Infraclass Eutheria represented by placental mammals Brief Summary of Vertebrate Relationships Ostracoderms First Vertebrates Jawless fish ancestor to jawless and jawed fish Sarcopterygii fish gave rise to first amphibians Stem labyrinthodont amphibian gave rise to stem reptile Stem reptile gave rise to all living and extinct reptiles birds and mammals Chapter 8 Reproductive Behaviors Modes of Reproduction Oviparous laying eggs fish amphibians reptiles birds Viviparous giving birth to non shelled live offspring cats dogs and horses Ovoviviparous female retains eggs in her body and the young hatch from the eggs and are born alive some snakes and sharks Mating Systems Monogamy association between one male and one female 90 of birds are monogamous 3 of mammalian species are monogamous Polygamy association between an individual that has more than one mate at the same time Polygyny association between one male and two or more females most mammals are polygynous or promiscuous Polyandry association between one female and two or more males rare occurs in less that 1 of all bird species reversal of sex roles fraternal polyandry women are married to brothers Chapter 9 Social Behaviors Selected Social Behaviors Matriarchal group group led by females elephants Patriarchal group group led by males lions Meerkat Manor Video Flower leader and dominant female of the Whiskers Group 29 meerkats Zaphod dominant male and Flower s mate father of most of young Mozart sister of Shakespeare Shakespeare older son of Flower and Zaphod brave and caring Chapter 10 Territorial Behaviors animals will defend a territory that contains their nesting sites sources of food and cover for protection Birds use song and certain displays to keep others out Mammals scent marking Maternal Behavior behavior and interactions shown by the mother to her young Predator Protection Predator Avoidance and Safety of Young Don t be seen heard or smelled Defend as a group Stay in large groups Run away Lead predator away Have a sentinel
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