Lectures 2-4 Flashcards
Ontogeny
EMbryonic development of an organism after birth (reproductive maturation)
Teleology
Characteristics develop out of need, untestable…birds needed to fly so developed wings.
Von Baer’s law
Features that develop earliest in ontogeny are the oldest phylogenetically and features that develop later are more recent development. Not exactly true…
Synthetic theory of evolution [3 components]:
Organic evolution, Genetic diversity, and natural selection….Ernest Meyer
Organic evolution
Based on fossil record, organisms today aren’t same as prior in Hx. Based on fossil record
Genetic diversity
All members of population demonstrate genetic variation d/t sexual reproduction (meiosis/recombination) and mutation
Natural selection
Co-developed by Alfred Wallace and Darwin. Those w/ best chance survival have better chance fertile offspring; thus there genotypes will become more frequent in population over years
Theory of acquired characteristics and author:
Jean Baptiste Lamarck- AN organism can develop anatomical changes in response to specific pressures it encounters. Ex: blacksmith strength
Analogy
Similarity in function, but different in anatomy/embryological development. Ex: dolphin and carp have similar functions for limbs…differ in structure though
Homology
Similarity in structure but different function [d/t inheritance from common ancestor]. Ex: lizard and dolphin limbs similar in structure differ in function-did have common ancestor.
Homoplasy
Structural similarity in different organisms not d/t inheritance from common ancestor
Convergence
Gaining similar characteristics by species w/ different ancestors..ex: Dolphin, shark, and icthysaur all have similar body from same ancestor..maybe d/t environment
Parallelism
Common ancestor and independently gains characteristics…ex: Long feet and bushy tail mice common ancestor and both developed these characteristics
Paedogenesis and the origin of vertebrates:
The hypothesis is that larval tunicates have the tail intact and became able to reproduce…so the tunicates gave rise to cephalochordates and vertebrates
First vertebrates appeared in which period, how long ago was this?
Cambrian; 570 million years
Characteristics of hypothetical common ancestor Echinoderms and chordates?
Most agree chordates have more in common w/ Echinoderms. Characteristics: Sessile/semi-sessile Deuterostomous Bilateral symmetry Ciliated larval form Lophophorates-can draw in water Ciliary feeders
Major anatomical characteristics of Amphioxous
Larval form similar to adults but no gonads.
Lack paired limbs and jaws
No vertebral column
Nerve cord dorsal to notochord but no brain
Lacks cartilage and bone
V shaped muscle segments and used for swimming
Mouth opens to pharynx
Endostyle located in floor pharynx to trap food particles and move them to intestines. Thought to be development of thyroid.
MAjor characteristics of urochordates
Sessile bag of fluid; w/ 2 hoses [incurrent siphon to pharynx w/ filtration slits & intestine and atriopore to excurrent siphon] CELLULOSE-like polysaccharide-tunicin-unheard of animal kingdom. Dermal epithelium and connective tissue -mantle; use ciliary action to draw water into pharynx through incurrent siphon. MEtamorphosis from tadpole-like larval stage. Larva head adheres to substrate “home” and tail collapses removing notochord and most of nerve cord.
Adult Urochordata vs. larva
Adult has no notochord or nerve cord…has gonads and ganglion though
Clade
Monophyletic group made up of an ancestor and all of its descendants
Cladistics:
The study of clades [monophyletic group made up of common ancestor and all its descendants]
Synapomorphies:
Derived characters that are shared by several lineages
Paraphyletic:
Includes a common ancestor and some but not all of its descendants.
Polyphyletic:
Includes descendants but not the common ancestor
Cladogram:
A diagram that shows a sequential hypothetical EVO. Branching pattern of a group of clades.
5 classes of fishes and give examples
Agnatha, Acanthodii, placodermii, Chondrichthyes, and Osteichthyes
Agnatha:
W/o jaws and paired appendages- ostracodermi and cyclostomata
Acanthodii
Streamlined body 1st of the jawed fishes- gnathostomes
Placodermi
1st jawed fishes in Gnathostomes: movable joint btw head shield and trunk. Paired pectoral and pelvic fins
Chondrichthyes
Shark, skates, Ray-no bone cartilage only
Osteichthyes
Paired fins, internal fin skeleton…made of bone
Ostracodermi
Oldest known vertebrates (570 my)..all extinct. During the Cambrian period. LAcked paired appendages and jaws. Pharyngeal pumping mechanism to draw in currents of water, dermal armor.
Prey not predator
Cyclostomata
Lacked jaws and paired appendages. More predator like..had pineal gland.round mouth.constant water cycle through mouth.
Anadromous
Larval grow in freshwater as filter feeders then move into marine environment becoming predators [lampreys]
3 major development that set gnathostomes apart from earlier fish?
Jaws [development of]
Appendages [paired]
Buoyancy mechanism [lungs/swim bladder]- allows fish to not swim and remain still. Sharks don’t have..
Major anatomical characteristic distinguishing sarcopterygians from actinopterygians?
Internal fin skeleton..
Sarco: cartilage/bone
Actin: spines
WHich Paleozoic era did fishes first appear?
Cambrian 570 my
Significance of the 3 major morphological developments in gnathostomes:
Jaws: were hyostylic (gave rise to ours autostylic)
Paired appendages: fins turned to feet
Buoyancy mechanism: gave rise to lungs for terrestrial states
List the four classes of tetrapods
Amphibia, reptillia, Aves, Mammalia
Early Devonian tetrapods
Labyrinthodonts- placed as amphibian
What group is thought to have gave rise to modern amphibians ?
Temnospondyls during the early Carboniferous
Characters of modern amphibians
Pedicellate teeth, Cylindrical vertebral centra, and 2 auditory ossicles—–salamanders
Characters of devonian Tetrapods
Devonian tetrapods represent transition from fish to land animal….tail w/ fin rays, begin to develop breathing nostrils, lungs well-developed, tougher skin, inner ear for sound in air not sound in water
3 orders of amphibians
Caudates, Anurans, and apodans
Caudates
“Have a tail” includes salamanders
Anurans
“Lacking a tail” frogs/toads
Apodans
“Lacking limbs” caecilians-wormlike
Anapsids:
No arch in the skull: 2 types—
Cotylosaurs and Chelonia
Which one of the anapsids is stem reptile for all other reptiles?
Cotylosaurs:
Resembled seymourian tetrapods, May have been several feet in length, dermal armor, skulls more laterally flattened rather than dorsoventrally as in amphibians
Distinguishing feature btw 2 grps of dinosaurs?
Pelvic girdle:
Ornithischians-tetraradiate pelvic girdle (bird hipped)
Saurischians- Triradiate (lizard hipped)
3 subgroups of modern lepidosaurs and skull differences:
Diapsid: 2 lateral openings behind orbit—sphenodon
Lizards: Lack Lower arch ventral to lower opening.
Snakes: lack the bony arch seperating the 2 openings
Why do dinosaurs form paraphyletic group?
It includes the ancestor of birds and dinosaurs but doesn’t include the birds
Reptilian characteristics in early birds:
Bony tail;
separate fingers w/ claws;
teeth
Theory of flight for birds:
Probably evolved from bipedal archosaur- flight may have evolved d/t:
Thermal insulation,
Insect-catching, better pursuit of prey/escape, allowed to roost in trees
Earliest group of synapsids
Pelycosaurs
Characteristics shared by mammals and advanced therapsids:
Secondary palate, Enlarged Dentary bone, Teeth and rib differentiation, Legs pulled in, illium extends forward, Elongated sacrum, feet well-developed,mandible jaw articulation
Mammal characteristics:
Live birth, Endothermy, Resp. Diaphragm, 4 chamber heart, Neocortex, Double occipital condyle, Mandible single bone, Bony secondary palate Loss of interclavicle Hair.fur Mammary glands
Earliest mammals:
Morganucodonts
Morganucodonts dentition:
Heterodont dentition w/ tricodont molars
3 groups of Modern mammals
Monotremes: egg-laying mammals
Marsupials: possum
Placentals: placenta
List and describe requirements for terrestrialism:
Dessication control: not drying out-pituitary;
Resistance to gravity: vertebra bony;
Changes in organs-special senses: lateral line system-> hearing/eyes;
Nitrogenous waste excretion; reproductive changes
