-series of rapid mitotic divisions in early embryonic development -increasing ratio of nuclear to cytoplasmic material -increases surface-to-volume ratio of each cell, improving gas and nutrient exchange
-Deutro vs proto
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Gastrulation
In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula.
-Can tell Triplo vs Diplo
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Subphylum Cephalochordata
lancelets (amphioxus)-oldest chordates -Suspension feeders -Pharyngeal slits for water to go in/exit -cilia on outside -Diatoms and dinoflagellates inside
**Features in adults AND larvae
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Ecdysis
periodic shedding of the cuticle in arthropods or the outer skin in reptiles
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Subphylum Urochordata
tunicates -> Chordate features ONLY in larvae -Adults are IMMOBILE and lose chordate features (Derived traits -> ancestors=chordates) -Only have pharyngeal slits
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Unikonta
amoebozoans and opisthokonts
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Subphylum Vertebrata
Vertebrates; cephalized chordates a. A vertebral column b. Closed circulatory system c. Neural crest -> Infolded ectoderm d. Bones e. Brain f. Cranium (skull)
**2 sets of hox genes
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Opisthokonta
the eukaryotic supergroup that contains the fungi, animals, and choanoflagellates
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Subphylum Cyclostomata (Circle Mouth)
Class Mixini and Petromyzontida -Jawless -Simple Vertebrates
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Clade Metazoa
all animals
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Class Mixini
hagfish (Not fish) -Jawless Craniates -Marine scavengers -skull, simple vertebra -Cartilaginous-> NO COLLAGEN -Make slime for protection
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Class Petromyzontida
Lampreys -Cartilaginous-> NO COLLAGEN -Jawless, vertebra-like extensions on notochord -Parasites; eat blood -> larvae suspension feed
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Subphylum Gnathostomes (Jaw Mouth)
-JAWS -> Predators -Additional hox gene cluster -Mineralized endoskeleton -Lateral line system -> better senses and bigger brain -Tetrapods -> legs and arms
**Fish, amphibians, reptiles, mammals
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Origin of Jaws
-Skeletal rods supporting pharyngeal slits fuse around the mouth -Other slits become GILLS for respiration -No more suspension feeding
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Chondrichthyes (cartilaginous fish)
Sharks And Ray fish & ratfish -true jaws and Cartilage endoskeleton -paired fins -hypertonic to Ocean -Must be constantly swimming
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Superclass Osteichthyes (bony fish)
-Endoskeleton made entirely of hard calcified bone -Operculum= protects gills and allows fish to draw in H2O and breathe -swim bladders= "Lungs" -> controls buoyancy -gills for respiration -Lateral line system -Oviparous
3 Classes: Class Actinopterygii Class Actinistia Class Dipnoi
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Class Actinopterygii (ray-finned fishes)
-Origin Silurian Period 444-419 MYA -Aquatic -Fins supported by long flexible rays -> maneuvering, self defense
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Class Actinistia (lobe-finned fish)
-Rod shaped bones surrounded by thick layer of muscle in pelvic and pectoral fins -3rd surviving group of lobe fins= survived on land -Silurian Period
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Class Dipnoi (lungfish)
-Gills= main organs for gas exchange
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Class Amphibia
Paleozoic- 365 MYA -Flattened head and arms come to sides -Presence of neck -Shell-less eggs -Frog= soft skin -Toad= rough skin
incisors= shredding canines= ripping and piercing molars= grinding
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mammal characteristics
-Warm blooded -High metabolism -Sweat glands to cool -specialized teeth -hair -Mammary glands -Extended care of young -Learned behavior
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Subclass Prototheria
monotremes (Porcupines) -Warm blooded -Lay eggs -> Young hatch and live outside mom -hair -NO NIPPLES -Milk glands
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Subclass Metatheria (marsupials)
-Live Birth -Temporary placenta -Underdeveloped young -> stay in mom's pouch -Attached to nipple -> feed off nipple for milk
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Subclass Eutheria (placental mammals)
-Live birth -Fully developed child after birth -Young held inside past egg feed development -Feed by umbilical cord attached to placenta -Long-term placenta -Feed off breast for milk-> NOT physically attached to nipple
**Convergent evolution with Marsupials -> look similar
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Tetrapods
vertebrate animals having four feet, legs or leglike appendages -digits on feet and arms -Neck= sep movement of head -Fusion of pelvic girdle and backbone -Ears-> detect airborne sounds -Absence of gills
-feathers -> Flight -forelimbs have become wings -lay eggs with hard shells -4 chambers in heart -Warm blooded high metabolism -Lungs and air sacs= one way flow -Hollow bones -Parental care and social behavior -One ovary -NO TEETH OR URINARY BLADDER
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Primates New Features
-Origins to 65 MYA -Insect eating nocturnal mammals -Derived Trait-> Life in trees -grasping hands and feet -Fully opposable separate big thumb -Fingerprints -Larger brain -Short jaws -Hand to eye coordination -Flat nails, no claws -Long parental care -Learned Behavior -Single births ANY time of yr
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Primate Groups
prosimians -Lemurs and Tarsiers -> more related to OG primates
anthropoids -Monkeys and Hominoids -> Split from Prosimians 45 MYA
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New World Monkeys
All species are arboreal -Nostrils open to the side -Many have prehensile tails. -Squirrel and Capuchin monkeys
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Old World Monkeys
Split from New World Monkeys 35 MYA Include arboreal and terrestrial species -Lack prehensile tails -Nostrils open downward -Rhesus Monkeys, baboons, macaques
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Hominoids
apes and humans Split from Monkeys 20-25 MYA -More flexible/learned behaviors -NO PREHENSILE TAILS -Larger brain to body ratio / larger size -Social Behavior
Orangutans and Gibbons -> Primarily Arboreal Gorillas, Chimps, Us -> Primarily Terrestrial
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Hominins
-Humans and our direct ancestors since split from Chimps 6-8 MYA
Major Groups: Australopithecus Paranthropus Homos -> some co-existed
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Hominin Evolution/Characteristics
Driven by Life on LAND -bipedalism -Smaller Jaw with SPECIALIZED teeth -> Omnivorous diet -Pronounced chin -Less Sexual Dimorphism -> no real harem/dominant male -Tool use -Language -Social behavior -Walking Upright -expanded brain -Decreased sense in smell nut increased vision and muscle coordination -Eyes are larger and directed forward -Mosaic Evolution-> Not all traits happened at same time
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mosaic evolution
a phenotypic pattern that shows how different traits of an organism, responding to different selection pressures, may evolve at different rates
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Chromosome anomaly
Other extant Hominids -> 2n=48 -2 Ape chromosomes fuse -> become humans with 2n=46
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Paedogenesis
The early development of sexual maturity in an adolescent -> Larger cerebrum in hominins
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Sahelanthropus tchadensis
The earliest pre-australopithecine species found in central Africa -OLDEST-> 6-7 MYA (discovered 2002)
-6.1 MYA-5.8 MYA (Discovered 2000) -Evergreen forest -> Not in open grassland -Oldest Bipedal Fossil Evidence
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Ardipithecus ramidus
4.4 MYA -"Ardi"-> most complete skeleton found -wooded environment-> contradicts open Savannah theory for origins of bipedalism -small brain -walked upright -big toe separated from other toes
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Australopithecus
the earliest humanlike creature 3-4 MYA -Fully upright walking -Human-like teeth and hands - 1/3 of modern human skull size -Lasted over 1 MY in South and East Africa
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Homo Naled
2.5-3 MYA (Not sure) (found 2012) -Base of Homo Genus -Fully Bipedal -Fine Hand/Motor skills
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Homo Habilis
1.6-2.5 MYA -Walked upright for 2 MY -USED Brains -Fashioned STONE TOOLS -Co-existed with Australopithecus for 1 MY
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Homo ergaster
1.6-1.9 MYA -Less sexual dimorphism and more monogamy -larger brains -Slender legs -> Long distance walking -> Migrations -Smaller teeth= Prepared/cooked food -Smaller fingers= no more climbing trees -More advanced tools and more habitats
Intermediate btwn Habilis and Erectus
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Homo erectus
300,000 YA- 1.8 MYA First to Migrate OUT to Europe and Asia -Larger populations -More advanced hunting -> Oldest evidence of use of fire -Java Man and Pecking Man
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Homo heidelbergensis
A transitional species between Homo erectus and Homo sapiens -Descended from H. ergaster in Africa and spread out
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Europe in ICE AGE: 3 populations LOSE CONTACT and speciate:
Europe: Neanderthals Asia: Denisovans Africa: Homo Sapiens (us)
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Homo neanderthalensis
40,000-200,000 YA -Buried dead -Hunting tools from stone and wood -Carnivorous -Larger brain size than us (Maybe)
**Interbred With H. sapiens -> 20% European genome is Neanderthal (Except Y chromosome 100% Sapien)
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Denisovans
41,000 YA -Formed from H. heidelbergensis -More closely related to Neanderthals than us -Not much info -> only have small DNA fragments -Fossils in Spain -> May have interbred with Neanderthals
**Papua New Guinea ppl have Denisovan DNA -May have been around until 60,000-110,000 YA
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Ethology
The scientific study of how animals behave, particularly in natural environments.
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behavior
what and how animals do things
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Reductionism
Single out/isolate variable you are testing
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causes of behavior
Ultimate Causation: Ecological/Evolutionary reason -> How to maximize fitness