Exam 2 Flashcards
Biological evolution
Is the change, over time, of the proportions
of individual organisms differing
genetically in one or more traits; such
changes transpire by the origin and
subsequent alteration of genotypes from
generation to generation with populations
of organisms
evolutionary history
- all organisms are related in a kind of pedigree; some are more closely related than others
- the pattern of evolutionary relationships can reveal important information about the appearance of novel traits and its effects on subsequent diversity
- provides a framework for comparison among sometimes distantly related organisms.
Inferring evolutionary history
- usually can’t observe speciation and extinction directly
- must be inferred from fossil record, geology, and reconstruction phyologenetic trees
Taxonomy
-theory and practice of describing biodiversity, arranging into a system of classification and devising identification keys
Alpha taxonomy
species descriptions
beta taxonomy
arrangement into a natural system of classification
gamma taxonomy
analysis of intraspecific variation and the study of evolution
Species according to C Tate Regan
“a group of organisms with distinctive enough
characters, that in the opinion of a competent
taxonomist, are sufficiently definite to entitle them to a
specific name”
species according to Ernst Mayr
“groups of actually or potentially interbreeding
populations that are reproductively isolated from other
such groups”
species Joel Cracraft
“a demonstrably monophyletic assemblage of
populations”
species Ed Wiley
“a single lineage of ancestor-descendant populations
which maintains its identity from other such lineages and
which has its own evolutionary tendencies and historical
fate”
Systematics
study of evolutionary relationships postulated to exist among species or higher taxa such as families and orders
-use cladograms and phylograms
Cladograms
show common ancestry, but do not indicate the amount of evolutionary time
-can show key transitions
Phylograms
branch lengths are proportional to amount of time
-can show when a species arose and when it went extinct based on branch length
Subphylym Cephalochordata
- Branchiostoma, amphioxis, lancets
- inverterate chordate
- accepted as sister group to vertebrates
- lack a cranium, brain, well developed heart, RBCs, gills
- segmented features
Life history and ecology of cephalochordata
- spawning in early summer, larval metamorphose into adult form in 2-5 months, adults live 1-4 years
- burrowing filter feeders, planktonic larvae
- ciliated pharyngeal cavity, endostyle
Hagfishes– myxiniformes
- most ancestral vert (controversial)
- some morphological data suggests monophyly of hagfishes and lampreys; vertically biting tongue, velum, nuc sequences info
- imperiled in parts of its range due to overfishing
hagfishes body form
• Elongate, eel-like, round buccal cavity with
rasping teeth and tounge
• Single gonad, rather than paired
• Four hearts: (1) posterior to gills; (3) just behind
mouth
• Respiration at gills; cutaneous
• Lack complete eyes, possess sensory barbels; slime glands and pores
• Taxonomy and systematics based on number of
gill ducts, slime pores
Hag fishes diversity and distribution
- world wide, marine, restricted to cold water
- few species occur in water shallower than 30m, limited by salinity and temperature
- one family (mxyinidae) with 60 species
hagfish life history features
- females produce few large eggs, direct development
- probably iteroparous
- age at maturity, reproductive lifesapn, spawning time and behavior unknown
- scavenger feeders
Lampreys- petromyzontiformes
- superficially resemble hagishes
- parasitic and non parasitic species
- produce ammocoete larva similar to Cephalochordate, but differ in feeding mechanism
lamp reys body form
• Elongate, eel-like, round buccal cavity, rasping
teeth and tongue
• Single gonad
• Single heart
• Respire at gills, branchial sacs, tidal ventilation
• Parasitic form with complete eyes; non-parasitic
eyes reduced
• Largest diploid chromosome number for a
vertebrate
lampreys diversity and distribution
- worldwide, temperate zone
- non parasitic (freshwater) parasitic (freshwater; anadromous)
- one family (petromyzontidae) 40 species
Conodonts
- known from fossilized teeth
- v shaped muscle bundles
- mineralized tissues
- notochord present
- ray like fin elements
ostracoderms
- much disagreement about the relationships of these jawless fishes
- possessed acellular dermal armor consisting of enamel, dentine, and bone
- occur first in marine strata then in freshwater
pteraspida (diplorhina)
- 6 families, 50 genera recognized
- evolutionary trend toward reducing dermal armor
- development of lateral projections
- extinct
- big bony plates
Cephalaspida (Monorhina)
- appear in the fossil record about 30 my after pteraspids
- cellular dermal armor
- inernal fin musculature
- ossification of endoskeleton–first time this is seen
- indirect development
where do jaws come from
- most widely accepted hypothesis is that jaws arose from anterior pair of visceral gill arch support
- key structures involved: nueral crest cells, chondocranium, dematocranium, spanchonocranium
Placodermi
-extinct gnathostimes, probably the most ancestral lineage (sister group to all other gnathostomes
-occur in first marine deposits in the Ordivician
-reduction in dermal armor
-craniovertebral joint
possibly pelvic claspers
Acanthodians
- earliest known jawed fishes
- sister to Osteichythes
- appear in the late Ordivician 440 mya
- two rows of ventral paired fins preceded by a spine
- most closely related to Osteichthyes because of bony operculum; branchiostegal rays from hypobranchial elements, and three otiths
Chordates
presence of notochord at some point in development; elaborates during development for most
difficulties in inferring evolutionary history
- soft anatomy not preserved in fossil record
- have to be able to date geographical matter
phylogenetic trees
- hypotheses of putting mutations together
- taxonomy reflects evolution
urochordata
-larval from has notochord even though adult form does not look like a chordate
post anal tail
common in all chordates
hagfishes– other information
- make a lot of mucous
- osmoconformers
- notochord persists through whole life
- can time themselves into knots
lampreys other info
- 7 distinct gill pores
- resemble hagfishbut have distinct eyes
- non parasitic have softer mouths while parastic have sharp teeth
- largest diploid number of any chordate
- pineal gland that can detect light fro body rhythyms
- pseudo vertrebrae
Where do jaws come from?
- most widely accepted hypothesis is that jaws arose from anterior pair of visceral gill arch supports
- give gill slits in species with jaw
Spiracle
precursor to ear canal
key structures involved in jaw formation
- neural crest cells
- chondrocranium
- dematocranium
- splanchonocranium
evolutionary drives for jaw development
- ventilation
- feeding
Placodermi
• Extinct gnathostomes, probably the most
ancestral lineage (i.e., it is the sister group to all
other gnathostomes)
• Occur first in marine deposits in the Ordivician
(470 my ago)
• Reduction in dermal armor (compared to jawless
fishes)
• 8-9 orders, 30 families, 50 genera
• Craniovertebral joint
• Possibly pelvic claspers (♂ reproductive organ)
Placodermi reproduction
- one of the first for internal fertilization
- sexual dimorphisma
craniovertebral joint
- hinge to move the head
- unites all placodermi
Acanthodians
- earliest known jawed fishes
- most ancestral bony fish
- bony operculum
- sister to ostiechythese
- appear in the late Ordivician (440 mya)
- two rows of ventral paired fins preceded by a spine
Acanthodians related to osetichythes because of
- bony operculum
- branchiostegal rays developed from hypobranchial elements
- three otoliths
Class chondrichthyes
• Cartilaginous skeleton with calcified vertebral elements • Males have pelvic claspers • Sutureless chondrocranium • Ceratotrichial fins • Placoid scales • Heterocercal tail
Key physiological features of chondrichthyes
- lack swim bladder
- lipid filled liver for buoyancy
- urea in high concentration (keeps proper ion concentration)
- Trumethylamine oxide (TMAO)
- possess spriacles and gill slits for respiration, varies from two stage pump to ram ventilation
subclass holocephali
• Chimaeras, ratfishes, plownose chimaeras, roughly 30 species • Possess pelvic claspers, and clasper on head in some species • Autostylic jaw suspension • Operculum-like flap covering gills -deep water fish -pennant shape -eat hard bodied stuff
subclass elasmobranchii
-• sharks, saw sharks, angel sharks, guitarfishes,
sawfishes, rays, skates
growth curve would have a small k
key features of elasmobranchii
• Chondrocranium with hyostylic suspension
• Large bodied, slow growth
• 5 pairs of gill slits (usually); six- and seven-gill sharks
(Hexanchidae)
• carcinogenic tumors were thought to be rare in
elasmobranchs; hypothesized to possess factors that are
tumoricydal, or prevent vascularization of tumors
(angiogenin antagonists)
Shark order heterodontiformes
- Family Heterodontidae
- 8 species, all marine; all oviparous
- Horn sharks
- Anterior teeth for grasping, posterior teeth for crushing
shark order lamniformes
-7 families
-16 species
-all marine
• Cetorhinidae - basking shark; plankton feeder
• Ondontaspididae - sand tigers
• Megachasmidae - discovered in 1976; 160 m depth; sub/tropical
Pacific
• Alopiidae – thresher sharks – large upper lobe of caudal fin
• Lamnidae – mackeral sharks; great white shark
Lamnidae
-mackeral sharks; great white
-– Pelagic, fast swimmers, highly predatory
– Nearly homocercal tail
– Megatooth shark may have exceeded 13 m (45 ft.)
shark order orectolobiformes
-7 familes
-31 species
-all marine
• Rhincodontidae – whale shark (up to 18 m)
• Ginglymostomatidae – two-pump respiration– mollusk eater
Shark order carcharhiniformes
-8 families
-210 species
-mostly marine
– Scyliorhinidae – cat sharks; usually small; tropical and temperate
– Carcharhinidae – highly predatory
• Bull shark (Carcharhinus leucas) occasionally found in freshwater
– Sphyrnidae – hammerhead sharks
Shark order hexanchiformes
-2 families
-5 species
-all marine
– Chlamydoselachidae– frill sharks
– Hexanchidae – cow sharks, six and seven gill sharks
shark order squaliformes
-3 families
-74 species
-all marine
– Widely distributed – Atlantic, Pacific, Indian Oceans, tropical to
subarctic latitudes
– Squalidae – dogfish sharks; usually small, inshore and deep water
scavengers (great nuisance to fisherman)
shark Order pristiophoriformes
- 1 family
- 5 species
- all marine
- pristiophoridae; saw sharks
shark order squatiniformes
- 1 family
- 12 species
- marine
- squatinidae; angel sharks
Ginglymostomidae
nurse shark
megachasmidae
mega mouth shark
carcharhinidae
white tip reef shark
rhincodonitadae
whale shark
galeomorph
filter feeder; basking shark
