Evolutionary History of Animals

Question 1

Chemosynthesis (Abiogenesis)

Answer 1

Abiotic production of organic molecules
Abiotic production of polymers
Abiotic formation of membranes
Self-replication

Question 2

Symbiosis

Answer 2

Two organisms evolve to living in close association with one another

Question 3

Endosymbiosis

Answer 3

Symbiosis with one partner living in the other

Question 4

Phototrophs

Answer 4

Create O_2 and also use it

Question 5

Chemoautotrophs

Answer 5

Mostly bacteria and archaea

Use movement of electrons to power formation of organic molecules

Question 6

Plants

Answer 6

Photosynthetic autotrophs
Existence on land allowed expansion of biosphere
3 organs: roots (anchor the plant and allow for nutrient exchange), stems (support the plant and conduct nutrients) and leaves (produce food via photosynthesis)

Question 7

Invertebrates

Answer 7

Symmetry: none, radial and bilateral
Cephalization
Orientation (dorsal/ventral, anterior/posterior and lateral/medial)

Question 8

Phylum Porifera

Answer 8

Porous
Sponges
Asymmetrical
No tissue or organs
Sessile (not mobile)

Question 9

Phylum Cnidaria

Answer 9

Radial Symmetry
Jellyfish, anemones…
Carnivorous
Some nerves and muscles
Mobile
Live in aquatic environments

Question 10

Phylum Platyhelminthes

Answer 10

Flatworms, tapeworms, flukes…
Simplest brains
Some organs, muscles, nervous tissue…
Live in aquatic environments

Question 11

Phylum Nematoda

Answer 11

Roundworms
No appendages or segments
Have a cavity that acts like an early circulatory system

Question 12

Phylum Mollusca

Answer 12

Snails, slugs, octopi, oysters…
No segments nor appendages
Some have shells

Question 13

Phylum Annelida

Answer 13

Segmentation allows for specialization of tissue
Earthworms, sandworms, leaches…
Non-jointed appendages
Multi-organ digestive system
Circulatory system

Question 14

Phylum Arthropoda

Answer 14

Jointed appendages allow for walking, defence, feeding, sensing…
Protein and chitin exoskeleton for protection
Segments allow for specialization: eyes, olfactory receptors, tactile receptors, open circulatory system with a heart, gas exchange breathing system…
Most successful phylum: size, diversity, distribution…

Question 15

Phylum Echinodermata

Answer 15

Pentamorous radial symmetry in adults
Larvae are bilateral symmetry (and segmented)
Adults are generally sessile
Hard, spiny exterior

Question 16

Phylum Chordata

Answer 16

Segmented, appendages, cephalized…
Notochord (flexible, structural cord that exists in all chordate embryos)
Dorsal hollow nerve cord (spinal cord)
Pharyngeal slits (to allow water entry as needed for closed digestive systems)
Muscular postnatal tail (tail that goes beyond anus with muscular/skeletal elements; allows for movement)

Question 17

Subphylums

Answer 17

There are 3 subphylum of chordata
Cephalochordates (lancelets) are invertebrates, filter-feed and are weak swimmers
Urochordates (tunicates) are invertebrates, filter-feed and adults are sessile
Vertebrates have a spinal column (replacing the notochord) that surrounds and protects the dorsal nerve cord, and they are craniates (have a head)

Question 18

Subphylum Vertebrates

Answer 18

Cephalization and craniation (which allows for a larger brain development)
Eye development
Mouth (and typically mandibles or jaws), which allows eating through hard surfaces
Internal mineralized skeleton
Sometimes called “craniates”

Question 19

Classes

Answer 19

In phylum chordata, they are Myxini and petromyzontida, placodermi, chondrichthyes, actinopterygii, actinista, dipnoi, amphibia, reptilia, mammalia

Question 20

Classes Myxini and Petromyzontida

Answer 20

Myxini are Hagfish and Petromyzontida are lampreys
Are jawless
Have unpaired limbs
Have no vertebrae (lampreys have an early form of vertebrae)
Have skeleton and cranium (all cartilage)

Question 21

Class Placodermi

Answer 21

An extinct class of armoured fish
Are thought to be the first jawed fish
Are in the superclass “Gnathostomes,” in contrast to Myxini, which are in “Agnasta” (or “agnathostomes”)

Question 22

Class Chondrichthyes

Answer 22

Cartilaginous fish (sharks and rays)
Have jaws and full cartilaginous skeleton
Have paired fins
Sharks give live birth (but fetus depends on egg and not on mother during growth), do internal fertilization and have a sense of smell

Question 23

Class Actinopterygii

Answer 23

Fish
Breathe by drawing in air through gills and storing it (which also controls buoyancy)
Have bony scales
Have a two-chambered heart that send low O_2 blood to gill slits
Can regulate salt balance (through osmosis)
Do external fertilization

Question 24

Classes Actinista and Dipnoi

Answer 24

Actinista includes Coelocanth (fish with lobed limbs that can walk underwater)
Dipnoi includes lungfish which also have limbs and use the air (take in air and can store it

Question 25

Class Amphibia

Answer 25

Lead double lives
Larvae are underwater and eat algae
Adults have limbs, lungs, and ears but must keep their skin moist and reproduce in the water

Question 26

Class Reptilia

Answer 26

Live on land, sometimes in dry environments
Skin is dry and scaly (keratin makes it impermeable)
Allow their offspring to develop on land after internal fertilization
More mobile on land
Amniotic eggs

Question 27

Amniotic Egg

Answer 27

Amnion → membrane surrounding embryo which provides hydration and shock-protection
Yolk sac → sac that provides nutrients into which blood vessels grow
Allantois → sac that stores waste (nitrogen)
Chorion → membrane to filter out CO_2 and enable entry of O_2
Shell → hard and protective, it prevents loss of water but allows gas exchange

Question 28

Birds

Answer 28

Bipedal (walk on two legs)
Adapted for flight
Skeleton is light and hollow, but strong
No teeth (too heavy), neck and backbone fused
Feathers are flexible (have different functions) and have evolved from scales
Eggs are incubated by parents (unlike most reptiles)
Organ adaptations → food is digested whole, broken down in gizzard (with rocks) and waste is quickly released and lungs facilitate gas exchange

Question 29

Class Mammalia

Answer 29

Hair (to stay warm)
Mammary glands (mother can feed infant without needing food)
Four-chambered heart
Endothermic (can hunt at night, can survive in various temperatures but need more food)
Heterodonts (incisors, canines and molars)

Question 30

Order Monotremata

Answer 30

Monotremes
Still laying eggs and hatching them like birds
Secrete milk onto their hair (platypuses have no nipples)
Show traits of birds and reptiles

Question 31

Placentals

Answer 31

Many mammals, including humans, for example, order primates, order carnivora, order catartiodactylia (hooves animals), order rodentia (rodents), order chiroptera (bats)

Question 32

Evolution

Answer 32

Change in the gene pool from generation to generation due to natural selection, mutation and genetic drift

Question 33

Natural Selection

Answer 33

Species are easily capable of overpopulation (and intraspecies competition)
The better characteristics will have greater odds of survival and reproduction to pass on their traits
Causes an increase inheritance of favourable traits (alleles)
Species adapt to local conditions over generations

Question 34

Fossils

Answer 34

They provide details on past species (including those that are extinct)
Fossils are very incomplete (only for hard tissue, for select organisms that did not get eaten or scavenged and environment was also a factor, in that fossilization conditions are needed)

Question 35

Fossils and Radiometry

Answer 35

Radiometric data (decay of radioisotopes) can inform us of age

Question 36

Continental Drift

Answer 36

Continents drifted apart from Pangea

Similarities in species and distribution are consistent with this

Question 37

Biogeography

Answer 37

Describes distribution of living organisms within a certain geography

Question 38

Anatomy and Physiology

Answer 38

Use physical properties to relate organisms
Not all physical similarities are useful
Homology → similarity that results from shared ancestry (bird eggs and snake eggs)
Analogy → similarity from convergent evolution (bird wing and bat wing)
Species is the unit of evolution

Question 39

Speciation

Answer 39

Process to form new and distinct life forms

Question 40

Divergence

Answer 40

When a common ancestor differentiates

Question 41

Convergence

Answer 41

When a similar trait is developed independently by more than one organism (analogy)

Question 42

Vestigial Structure

Answer 42

When an organ or structure is no longer used (or no longer used for its primary purpose)
Debated term
For example, our appendix, coccyx, wings on flightless birds, hind limb in whales

Question 43

Genetics and Inheritance

Answer 43

Can look at genetic sequences of a species
Can compare sequences (for nucleic acids or proteins)
Genetic differences are related to divergence
Molecular evolution can be used to construct phylogenetic trees

Question 44

Macroevolution

Answer 44

Large-scale variation that exists because of microevolution, such as between phyla, classes, orders, etc. (For example, becoming terrestrial or acquiring feathers)

Question 45

Microevolution

Answer 45

Mutation in alleles (many small changes lead to differences between species)