chapter 20 - edwardsville school district 7 ch 20_27 notes... · chapter 20 phylogeny . phylogeny...
TRANSCRIPT
phylogeny – evolutionary history of a species or group of species
systematics – classifying organisms & determining their evolutionary relationships
Pattern of Evolution
taxonomy – how organisms are named & classified
Binomial Nomenclature
Carolus Linnaeus (18th century) – Genus &
species
Dashing King Philip Came Over For Great spaghetti.
Con. 20.1
Phylogenetic tree may not match classification. Why not?
Phylogenetics is about evolutionary relationships (descent not phenotypes)
*branch points
*sister taxa
*polytomy (more than 2 descendant groups) – usually means something is in question
Morphological Homology
-similar # & arrangement of structure (mammals & humerus bone)
-analogous structures: same function (bats & birds fly)
Molecular Homology vs. Analogy
-# of DNA sequences that match
-same function of DNA sequences
- Homoplasies vs Homology
Con. 20.2
Cladistics (common ancestry)
Clade – groups that include the ancestral species & all of its descendants (also called a monophyletic group)
Paraphyletic – contains the ancestral species & some but not all of the descendants
Polyphyletic – 2 or more common ancestors & some of their descendants
Con. 20.3 p. 387
shared ancestral character – a characteristic that originated w/the ancestor
shared derived character – a characteristic only found in that clade
outgroup – a species or group that diverged before the ancestral characteristic
ingroup – group of study p. 388 fig. 20.11
Proportional Branch Lengths show amount of change in proportion to time.
What to do with so much DNA?!
Maximum Parsimony – simplest explanation (get rid of what you don’t need)
Maximum Likelihood – most likely sequence of evolutionary events (logical)
NOTE: Any phylogenetic tree is constantly changing with the influx of DNA data.
Molecular Clock
-each gene has its own clock
-absolute time of evolutionary change
-reliable average rate of evolution based on nucleotide, codon, aa differences
Con. 20.4
-same gene may evolve at a different rate in other organisms
Neutral Theory: if most of the proteins & genes don’t pertain to fitness then their clock should be regular like a clock
Debate
1.irregularities can be from natural selection
2.neutral genetic variation can also lead to diversity
3.beyond fossil record leads to assumptions
Horizontal Gene Transfers
- genes transferred from one genome to another by transposable elements, plasmids, viral, etc.
- can’t really determine when some organisms diverged
- What about protists?!
I can’t take the indecision!!
What Makes it an Animal?
1. Must ingest & use enzymes inside body
2. Plasma Membrane – no wall
3. Most move at some time in their life span
4. Sexual reproduction
5. Hox genes (development of embryos)
When Did Animals Arrive?
Neoproterozoic Era
•565-550 millions years ago
•Ediacaran biota: multicellular eukaryotes (sponges, cnidarians)
Paleozoic Era
•542-251 million years ago
•Cambrian explosion
•First arthropods, chordates, echinoderms
•Predators have better equipment
•Adaptation to land
Mesozoic Era
•251-65.5 million years ago
•No groups but evolution occurred due to new habitats
•Dinosaurs, first mammals, flight
Cenozoic Era
•65.5 million years ago to present
•Mass extinctions of both terrestrial & marine animals
•Rise of the mammals
•Humans
BODY SYMMETRY 1) Asymmetrical: no pattern 2) Radial symmetry: parts are organized in
a circle around an axis
3) Bilateral symmetry– 2 halves on either side of a central plane anterior – toward head or front posterior – toward tail or back dorsal – top ventral – abdomen or bottom
• animals tend to exhibit cephalization
3 Tissue Layers: -ectoderm: outer layer & will become the epidermis & nervous system -mesoderm: middle layer & will become most of the organs & tissues -endoderm: inner layer & will become the innermost lining of our digestive tract (archenteron)
diploblastic – 2 germ layers triploblastic – all 3 germ layers
Body Cavities
coelom – fluid or air-filled space
coelomates – suspend organs (mesoderm)
pseudocoelomates – not quite false (mesoderm & endoderm)
acoelomates - solid
Protostome & Deuterostome Development
• Spiral cleavage
• Determinate cleavage
• Coelom from splits in mesoderm
• Mouth forms from blastopore
• Radial cleavage
• Indeterminate cleavage
• Coelom from mesodermal outpocketings of archenteron
• Mouth forms from secondary opening
PHYLUM PORIFERA = Sponges
• Least complex animals
• Simple body plans
• No true body tissues,
organs, or systems
Sessile: do not move
Obtaining Food • Food is filtered out of the water =
suspension feeding
• Choanocytes (collar cells) pull the water thru the ostia
• They have flagella that help move water thru bringing in O2 & carrying away wastes (leaves via osculum)
• Nutrients are distributed thru the body by amoebocytes
• Compound cribrostatin kills penicillin-
resistant Streptococcus
• The body is supported by a skeleton made
of spongin (flexible protein fibers),
spicules (calcium carbonate particles), or
both
PHYLUM CNIDARIA
• Diploblastic, radial
• More complex than
sponges
• Have tissues and few simple organs
• Most live individually except
for coral & hydra
• Most live in salt water except for hydra
2 Body Forms
Polyp: vase shaped
• Sessile
• Mouth up
• Hydra, sea anemone
Medusa: bell shaped
• Free swimming
• Mouth down
• Jellyfish (Portuguese Man-of-War)
Feeding & Defense
• Arm-like tentacles surround mouth
• tentacles contain stinging cells
(cnidocytes) used to capture food &
to protect
• When stimulated, its nematocyst
(poisoned barbed harpoon) can
paralyze or ensnare prey
PHYLUM CTENOPHORA
(comb jellies)
• move thru water by beating their 8 rows of cilia
• capture prey w/ sticky substance secreted by colloblasts
• The apical organ enables them to sense their orientation in the water
• Most are hermaphroditic
• Many have bioluminescence
PHYLUM PLATYHELMINTHES
• Flatworms
• bilateral symmetry
• Exhibit cephalization
• Triploblastic
• Acoelomates
• Protonephridia – tubules w/ciliated cells,
pull fluid through
Planarian Neural Control
• more complex than nerve net of
cnidarians
cerebral ganglia: serves as simple brain
• sense light w/ eyespots
Tapeworms
• can live in the intestines of almost all vertebrates
• surrounded by tegument
• Attach to the host w/ scolex (hooks and suckers)
Tapeworm
Structure • NO light-sensing
organs, mouth,
gastrovascular
cavity, and
digestive organs
• Produces new
body segments
(proglottids)
behind head
(may exceed 10
m long)
Each segment has both male & female organs
• eggs are fertilized in segment • segment breaks off & leaves host’s body
PHYLUM ROTIFERS
• tiny
• fresh, marine, damp soil
• alimentary canal – digestive tube
w/separate mouth & anus
• pseudocoelom (serves as hydrostatic
skeleton)
• crown of cilia
Phylum ECTOPROCTS & BRACHIOPODS
• Lophophore: crown of ciliated
tentacles surrounding the mouth
• U-shaped alimentary canal
• Pseudocoelom
Ectoprocts:
• colony encased
in exoskeleton
• common name is
bryozoans
Brachiopods:
• look like bivalves
• all marine
• attached to sea
floor by a stalk
PHYLUM NEMATODA
• roundworms
• largest phylum of worms
• slender, tapered at both ends
• alimentary canal
• pseudocoelom
• longitudinal body wall muscles
• 2 body openings (mouth & anus)
• covered by a protective cuticle
• Most species are free-living;
some parasites
• separate sexes
Types of Roundworms
A) Ascaris - infects pigs, horses, and
humans.
B) Hookworms - intestinal parasites
that feed on blood
C) Trichinella - infects humans, other
mammals
D) Pinworms- common human
parasites (do not cause serious
diseases)
Phylum MOLLUSCA
• “soft bodies”
• clams, snails, slugs, squids, octopuses
• Bilaterally symmetric invertebrates
• Some have a calcium carbonate shell
• coelomates
• Most aquatic mollusks and
annelids have a larval stage =
trochophore
Cilia
mouth
anus
Mollusk Body Plan
visceral mass: contains body organs
head-foot:
Head- mouth, sensory structures
Foot- large, muscular organ for locomotion
mantle: layer of epidermis that covers visceral mass
• secretes the shell or protects the body if lacking a shell
PHYLUM ANNELIDA
- “little rings”
• bilaterally symmetrical, segmented worms
• coelomates, divided into separate compartments by partitions
• have external bristles (setae) and some have fleshy protrusions (parapodia)
Phylum ARTHROPODA
• Largest animal phylum
• “jointed legs”
• Have body segments w/ appendages
• high degree of cephalization (antennae
and compound eyes
• open circulatory system
Body regions- • head, thorax, and abdomen • 2 or 3 can be fused together
•Body Cavity &
digestive system
possess mouth &
anus
•Nervous system
is similar to
annelids, but w/
larger brains
Skeletal Structure
• Have an exoskeleton
• Made of protein & carbohydrate = chitin
• Sheds exoskeleton as it grows = molting
1) Animal splits old, tight exoskeleton
2) Crawls out 3) Puffs up w/ air or water 4) Secretes new exoskeleton (very vulnerable)
PHYLUM ECHINODERMATA
• “ spiny-skinned”
–Sessile or motile
–pentaradial symmetry
–endoskeleton
–water-vascular system
–tube feet
Structure
• Endoskeleton of calcium carbonate plates (ossicles) supports and protects the body
(1st animals w/ endoskeleton)
• NO circulatory, excretory, or respiratory organ systems
• Nervous system- nerve ring and radial nerve that runs along each arm
Water Vascular System
• Network of water filled canals
• Tube feet act like suction cups for moving & feeding
Parts:
Madreporite- opening on top
Ring canal- center circle
Radial canals- go from ring canal
into each arm/ray
Ampulla- like “bulb” of an
eyedropper
Tube feet- apply suction to a surface
Characteristics of all Chordates
• Notochord – flexible rod-like structure on dorsal side of animal; site of what will be the spine
• Dorsal hollow nerve cord – dorsal bundle of nerves (spinal cord)
• Pharyngeal slits – paired openings in throat behind mouth; turn into gills in fish; fuse to form pharynx & ear canals in human
• Muscular, post-anal tail – muscle attachment w/skeleton
Subphylum Cephalochordata
• lancelets
• Retain notochord, dorsal nerve cord,
pharyngeal pouches, and postanal tail
thruout life
• feed by filtering water thru slits in
pharynx
• Invertebrate chordates
Subphylum Urochordata
• tunicates or sea
squirts
• Most are sessile
as adults
• barrel-shaped filter
feeders
• hermaphrodites
* There are 3 separate classes of fish with over 30,000 species!—Account for more than half of all living vertebrates.
Class Agnatha
Class Chondrichthyes
Class Osteichthyes
Class Agnatha (Jawless Fish) Lamprey, hagfish
• Both have round mouths, long tube-like bodies covered w/slimy skin
• Neither have scales or paired fins
• Skeleton is made of cartilage which is tough & flexible
• Hagfish lives in saltwater (a scavenger)
• Lamprey lives in both salt & freshwater
It attaches by suction, cut into fish, then
feed on blood & body fluids (parasite)
Class Chondrichthyes
• Cartilaginous fish: sharks, skates, rays
• Skeletons of cartilage covered with thin layer of CaCO3
• Moveable jaws
• Scales resemble teeth; skin feels like sandpaper
Class Osteichthyes
• Bony fish: bass, blue gill, zebra, etc.
1)Operculum – bony flap that helps protect gills & helps pull water through for breathing by opening & closing—also helps in communication,
(flared gills show aggression in some
species)
2)Heavy bony skeleton is strong and allows for attachment and use of powerful muscles. Ossification is the complete replacement of cartilage by bone.
3)Lateral Line System •is a special sensory system extending on both sides along its length •Water movement causes nerves to send messages to the brain •can detect motionless objects by the movement of water that objects reflect
3 Kinds of Bony Fish 1)Lobe-finned fish - fins are lobe-like &
fleshy; thought to be extinct until 1938 when one was netted in South Africa
- Coelacanth: brackish waters 60 caught
-different from ray-finned fish in that its
fins have several large bones with
muscles attached, are large and fleshy,
and in many cases are jointed
2)Lungfish - has both gills & lungs which allows them to live in shallow waters that dry up during summer & burrow in mud when water dries up; found in S. America, Australia, Africa
3)Ray-finned fish - fins are made of long thin bones covered w/skin; bass, catfish, blue gill, swordfish, parrotfish (most bony fish)
-They have an internal skeleton of parallel bony rays that stiffen and support each fin.
Buoyancy - swim bladder (air sac) allows the fish to adjust its density so it can rise or sink without swimming
- transfer of gases (mostly oxygen) between swim bladder & blood varies
- deep sea fish often have oil in their swim bladders - some bottom dwellers don’t have swim bladders
Swim bladder
Tetrapods
• Amphibian means “double life” (they spend time on land & in water)
• ectotherms
• smooth, moist skin that oxygen & carbon dioxide exchanges through (gas exchange also occurs through lining of mouth)
• small sac-like lungs for breathing
Amphibian Metamorphosis
• The change a larva undergoes in order to become an adult
• rate at which it grows & the length of time they spend as a larvae depends on the species, water temp. & food
• changes occur in their bodies & in food supply (yolk, herbivore, carnivore)
CHARACTERISTICS,…
1)Live in water and on land—eggs are usually laid in water and fertilized externally, larva live in water, and adults live on land. 2)Gills and Lungs—Larva have gills, but by adulthood, most gills are replaced by lungs
3)Cutaneous Respiration—Frogs, salamanders, and caecilians supplement their lungs by absorbing oxygen through their moist skin 4)Pulmonary veins—After the blood is pumped through the lungs, two large veins return the oxygenated blood to the heart to be pumped to the rest of the body. (Allows for greater blood pressure)
5)Three chambered heart—A partially divided heart where the ventricle (chamber pumping blood from the heart) contains a mixture of oxygenated and deoxygenated blood which is delivered to the amphibian’s tissues.
Three orders: Anura (without tail) = frogs and toads Urodela (visible tail) = salamanders and newts Apoda (without foot) = caecilians (worm-like and nearly blind)
--Most anurans return to water to reproduce --Eggs are laid directly in water and fertilized externally --Tadpole (larva) hatches and lives in water (most as herbivores) --After considerable growth, tadpoles change into adults by a process called metamorphosis.
Characteristics of Reptiles
• Ectotherm
• thick, dry, scaly, waterproof skin (prevents animal from drying out or injury)
• 4 legs w/claws (claws used for digging, climbing, running)
• vary in size, shape, color
• live on every continent except Antarctica
•Live in every ocean except the polar regions
•breathe w/lungs
•3 chambered heart (lower chamber partially divided to keep oxygen rich blood from blood of the body)
Mmmm!!!
Development of the Amniotic Egg • Internal fertilization • complete environment for the embryo • egg has a leathery shell • hatch fully developed
•Parts of the egg:
- Yolk: large food supply
- Amnion: filled w/fluid; shock absorber
- Allantois: gas exchange which then goes
to the pores on the shell
- Chorion: transfers nutrients & wastes
Maternal Care in Reptiles
• Most fish, amphibians, & reptiles do not provide care for their young
• but alligators & crocodiles stay near the nest & guard the eggs; they often respond to sounds made during hatching, dig out the babies and carry them to water
Birds are vertebrates of the Class Aves
(this class contains about 10,000 different
species)
Some of their characteristics include:
-- endothermic (warm blooded) = they can
regulate their body temperature regardless of
external conditions
-- only animals with
feathers
Characteristics continued,…
-- lay amniotic eggs (an egg that provides a complete environment for the developing embryo) with shells
-- the shell is made of calcium carbonate (CaCO3)
--females lay from 2-8 eggs at one time…these are called a “clutch”
3. Feathers…2 kinds
--contour feathers are used
to fly, give the birds their
coloring and sleek shape
--down feathers are soft,
fluffy and insulating helping the
birds maintain a constant body
temperature
Flight adaptations continued,...
4. Keen senses, especially sight, enable birds
to spot prey
5. Efficient body systems
are necessary because
so much energy is
required for flight.
Birds have a true 4 chambered heart (like us).
Because they have such high metabolism their
heart rate is also very high = over 1000 beats
per minute.
ACCORDING TO SCIENTISTS,…there are not many
fossils of birds around because their bones are so
light and hollow. There has been a lot of debate
about the origin of birds:
- thought to have descended from reptiles
-missing link (225 million yrs)
Protoavis = hollow bones,
no feathers
-missing link (150 million yrs)
Archaeopteryx = feathers,
but solid bone
Mammalian Traits: -Endothermic -Skin/Hides (clothes, footballs) -Hair (even dolphins) -Mammary, Oil, Sweat glands -Maternal care for young
Body Systems: -4 chambered heart -well developed lungs containing alveoli -lobed brain -carnivores have short digestive systems as compared to herbivores
Classification: 1.Monotremes – lay eggs w/tough leathery shells - no nipples, young suck milk from mom’s fur
2. Marsupials – pouched mammals that give birth to tiny immature offspring
--Mostly Australian and neighboring islands --Opossum
3. Eutherians (placentals) – embryos develop inside uterus - Placenta is a sac-like organ that is developed by the growing embryo that attaches to the uterus
--Food & oxygen is absorbed from the mother’s blood. --Umbilical cord attaches embryo to the placenta & takes food & nutrients to the embryo while removing wastes.
Primates -Opposable thumb: grasping hands & feet -Digits have flat nails, not claws -Skin ridges (fingerprints) -Large brain -Flat face
Humans -upright -bipedal -larger brain * language * symbolic thought * manufacture & use complex tools
Hominins Australopiths >human-like hands & teeth >bipedal >”Lucy” >very small body & brain Homo >tools found w/them >larger brain >long, slender legs >size difference between male & female less dramatic
Neanderthals >buried their dead >hunting tools Homo sapiens >genome transformation >cave paintings >natural selection