Lecture 17 Flashcards
Vertebrates
Development of a skeletal system and more complex nervous system - better ability to chase pray and run from predator
Most vertebrates have vertebrate that
enclose the spinal cord - replaces the mechanical roles of the notochord
Early diverged vertebra
No jaws, cartilage skeleton composed of extracellular matrix proteins like collagen
Cartilage can be mineralized with calcium for added support
Gnathostomes “jaw mouth”
Jaws: Hinged structures that enable animals to grip food items/slice them
cartilage fish (sharks, rays)
- One of the biggest and most successful vertebrate predators in the ocean
Predominantly cartilage skeleton
Limited use of mineralization for gnathostomes may be a
derived trait for these species as mineralization was present before they diverged from other vertebrates
Ray finned fishes and lobe finned fishes
Nearly all have ossified (bony) endoskeleton with a hard matrix of calcium phosphate
Ray finned fishes
- fins are made of bony rays connected with webs without muscular structure
- most of the extant fish species are ray finned
Lobe fin fishes
- Pectoral and pelvic fins have a thick muscle supporting the bony fin
- Muscular fins can be used to walk on the bottom of the water
- Not a lot of extant species (with exception)
3 major groups of lobe fin fishes
coelacanths: The living fossil that is believed to have remain unchanged from its ancestral shape for 400 million years
Lung fish: fish who has lungs as the means for gas exchange (in addition to gills)
Tetrapods: Sister group of lung fish who adapted to life on land
- muscular, pectoral and pelvic fins of lobe fin fishes evolved into limbs with digits
tetrapods
are gnathostomes that have limbs with digits
- diverged 365 million years ago
Limbs support animal’s weight on land while digits efficiently transmit forces to the ground when walking
Limbs changing into hands, wings and flippers
Amphibias
Salamanders, frogs
Amphibian refers to the dual life stages of frogs:
Tadpole: Aquatic larval stage, herbivore, legless, tail, gills
Frog: terrestrial adult stage, carnivore, legs, tailless, lungs
Many amphibians are strictly
aquatic or terrestrial
- still need to inhabit moist habitat
- Major gas exchange through skin
- Lays egg in moist environment or in water: eggs are not well protected from desiccation
Amniotes
Are tetrapods with terrestrially adapted eggs
- reptiles and mammals
Amniotic eggs contain
specialized membranes to nurture the embryo
- Amnion is the membrane that encloses the amniotic fluid which the embryo floats in
- Other membranes function in gas exchange, transfer of nutrients, waste storage
Amniotic eggs allow
terrestrial organisms to nurture embryo without having access to a body of water
Allatonois and chorion
Amniotic sac for waste disposal
Chorion: gas exhange
Many amniotic eggs have
a shell, others lack a hard shell and develop inside the parent’s body
Reptiles
Turtles, lizards, snakes
Many reptiles such as lizards are ectothermic
“cold blooded”
Use the environment (sun/shade) to regulate their body temperature
Birds
- endothermic
- Use metabolic activity to maintain body temp
- Less energy efficient but resilient to harsher environments
Mammals
Amniotes that have hair and produce milk to nurture the young
Mammals are endothermic with high metabolic rate
- hair and fat layer under skin provides insulation
Have a larger brain for body size
- allows complex learning behaviour such as offspring learning skills from parents
Milk
balanced diet rich in fats, sugars, proteins, minerals and vitamins
- produced in mammary glands
Monotremes
found only in austria and new guinea
- platypus and echidnas
- lays eggs was with other non mammalian amniotes
three mammalian types
monotremes, marsupials, eutherians (placental mammals)
Marsupials
Kangaroos, koalas
Embryo develops inside the female body, nurtured by the placenta
Child born very early in development and gets nourished in the mother’s pouch
Most extant marsupials are in the
Australian region
- opossum are the few marsupial species that still survive in north/central america
Convergent evolution may have given rise to many marsupials which look similar to placentals that occupy similar ecological niches
Eutherians (placental mammals)
Have placenta that are more complex than marsupials
- longer pregnancy
- young eutherians complete their embryonic development within the uterus
Various life forms and habitats
- wide range of food, meat, insects
Teeth of mammals bear a variety of sizes and shapes adapted for chewing many kinds of food
- variety is mainly observed in mammals and is one reason for their success
Mammals and digestive tract
Large expendable stomachs are common on carnivorous vertebrates
- need to eat large when they can, long intervals between feeding
Herbivores and omnivores have longer alimentary canals relative to body size as compared to carnivores
- vegetation is more difficult to digest rather than meat because of cell walls
- longer digestive tract furnishes more time for digestion and more surface area for absorption of nutrients
Gut micrbiome - adaptation of cows
We coexist with beneficial microbes living in the intestine
mutalistic gut micrbiome is important
in herbivores
Vertebrates can not digest cellulose cell wall of plants to convert it to energy
Many herbivores host mutualistic bacteria and protists in fermentation chambers of their alimentary canals
- microorganisms digest cellulose to simple sugars that the animal can absorb
Ruminants like cows
mix their food with mutalistic microbes in their multiple stomachs and regurgiate/rechew them before full digestion
three main groups of primates
lemurs, lorises, bush babies
tarsiers
anthropoids: monkeys/apes
earliest known primates were
tree dwellers
All primates have thumbs that is separate from other fingers to easily grasp branches
All monkeys and apes have fully opposable thumbs
- can touch the ventral (fingerprint) side of all 4 fingers with the ventral surface of the thumb
primate properties
- eyes on one side of the face (overlapping vision) gives better depth of perception
- Large brain, short jaws and flat face
Well developed parental care and complex social behaviour
Apes
Gorilla (gorilla sp.)
Humans (homo sp.)
Chimpanzees (pn sp.)
Shared traits for apes
- usually larger than monkeys
- no tail
- only gibbons and orangutans are primary arboreal (lives on trees)
No bipedal locomotion yet
Hominins
Extinct species which are more closely related to humans than to apes
Bipedal locomotion seen in early hominins (6.5 million years ago)
Multiple lineages of bipedal hominins existed throughout the history of evolution
We (homo sapiens) are the only hominin lineage which survived; others are extinct
hominins invention
use of tools may have evolved after bipedal locomotion
evidence shows hominins cutting flesh from bones of animals
other non hominin apes can use tools too
- orangutans putting sticks into holes to fish food
Genus homo
early homo all spread from africa into europe/asian regions as they diversified
homo habilis 2.4-1.6 million years ago
Homo ergaster 1.9-1.5 million years ago
Neanderthals
Homo neanderthalensis
- burying dead
- hunting tools from stone and wood
extinct 28000 - 40000 years ago
Is a different lineage as compared to humans but some gene flow did exist between the two species via inbreeding
Homo sapiens (human)
200000 years old (0.2 million)
Bipedal locomotion
Language, symbolic thought, artistic expression, manufacture and use of complex tools
reduced jawbone, jaw muscles, shorter digestive tract
Scientific classification of human
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primate
Family: Homindae
Genus: Homo
Species: Homo sapiens
many cave paintings were drawn since at least
30000 years ago
Life on earth
Sunlight -> plants (oxygenic photosynthesis, mutalistic bacteria make provide other nutrients like nitrate) -> Cow (eats grass and produces milk with mutalistic bacteria help)
-> milk -> yogurt (fermentation by gram positive bacteria) -> human consumption
