Lecture 1 Flashcards
What is systematics?
The study of biological diversity using phylogeny
Describe phylogeny
The evolutionary history and relationship between groups of organisms (e.g. species)
What does systematic knowledge provide?
A framework for interpreting biological diversity
As this is done in an evolutionary context, what does it allow?
Examination of how different attributes of animals change over time
What is taxonomy?
The description, identification and classification of species (new species are still being identified and described)
What is Nomenclature?
A standardised system of naming taxa
What is classification?
The arrangement and hierarchy of taxa (vertebrate classification is a mess- lots of subunits etc.)
What does phylogenetic systematics or cladistics suggest?
Shared derived characteristics constitutes evidence that the species possessing these features share a common ancestry. E.g. shared derived features represent unique evolutionary events that may be used to link species together in a common evolutionary history
What can relationships among taxonomic groups (e.g. species) be represented in?
In a cladogram or phylogenetic tree, a branching diagram that shows the best estimate of phylogeny based on the data used (e.g. genetic or morphology)
What derived characters used for?
To link monophyletic groups, groups of taxa that consist of a common ancestor plus all descendants of that ancestor
What are derived characters used for?
To link monophyletic groups, groups of taxa that consist of a common ancestor plus all descendants of that ancestor
What do paraphyletic and polyphyletic groups include?
A common ancestor and some, but not all, of the descendants of that ancestor
Give an example of a polyphyletic groups
Recent molecular data supports river dolphins as a polyphyletic group because Indian river dolphins do not share the same common ancestor as other river dolphins
What are chordates?
The animals that gave rise to the vertebrates with bilateral symmetry
What class of animals do the chordates belong to?
Deuterostomia
What do chordates have?
- notochord (dorsal rod of specialised nerves)
- dorsal nerve chord (hollow tube just above the notochord
- pharyngeal pouches (gill slits)
What are the 3 phyla of Chordata?
- Urochordata
- cephalochordata
- vertebrate
When did chordates evolve?
540 million years ago (Precambrian)
How many species of chordate are there?
52,000
Why are vertebrates good to use as a model for studying evolution?
. Monophyletic group
. Free living (most)
. Basic anatomy and development in common (common features)
. Diversity of form and function can be related to adaption and evolution
. Best studied eukaryotic group mainly because there is a very good fossil record
Give examples of myxinoidea and petromyzontoidea (jawless fish)
Hagfish and lampreys
Give examples of Elasmobranchii and holocephali (cartilaginous fish)
Sharks, rays, skates, rat fishes
Give examples of Actinopterygii (Ray-finned fish)
Bichirs, bowfins, gars, sturgeons, teleosts (most recent)
Give examples of Sarcopterygii (lobe-finned fish)
Coelacanths and lungfishes
What did sarcopterygii (lobe-finned fish) give rise to?
The terrestrial vertebrates
Give examples of Lissamphibia (amphibians)
Salamanders, frogs, caecilians
Give examples of amniotes
Reptiles, birds and mammals
Give the extant higher vertebrates: amniotes
. Testudines- turtles, tortoises, terrapins
. Lepidosauria- tuatara, lizards, snakes
. Crocodilia- alligators, crocodiles, caymans
. Aves- birds
. Mammalia- mammals
What are the most diverse group of extant vertebrates?
Ray-finned fish (Achinoterygii)
Give common features of vertebrates (look on the document for more)
. Postanal tail (for movement in some vertebrates)
. Pharyngeal pouches in lower chordates
. Vertebral column
. Specialised sensory organs, a lot of sensors to understand your environment
. Brain at anterior end of nerve cord, enhanced skull region that comes with a backbone
. Closed-loop circulatory system (heart, arteries, capillaries, veins)
. Myomeres (muscle segments)
What does the vertebral column develop from?
The notochord
What did the pharyngeal pouches in lower chordates evolve into?
Gill slits in fishes and amphibians, and structures in throat and ear in mammals
Why are the vertebrae important?
They protect the spinal cord and is important for muscle attachment (size of bones can tell you a lot about the muscles themselves)
Organs of vertebrates are organised into how many systems?
10
All systems tend to be separate but there are some links between them
When did class Agnatha- jawless fish originate?
500 million years ago (ancient vertebrates)
How many Agnatha species are there in total?
90-100 (ranges based on classification system)
Describe Agnathans and how you identify them
. Have a cartilaginous skeleton (not bone)
. Characterised by absence of paired fins (may have dorsal and central fins but not paired fins)
. Seven or more paired gill pouches that are exposed
. No identifiable stomach or any appendages
. Most are parasitic (lampreys tends to be-attach to host and with their teeth they east away an area which then oozes blood into the animal because it doesn’t have to chew anything it doesn’t need a stomach) or scavenges (hagfish tends to be)
. Fertilisation and development are external
When did the class Osteichthyes originate? However when did jawed fish first appear?
500 million years ago, jawed fish- 410 million years ago
What is the largest class of vertebrates in existence today?
Osteichthyes- bony fish
How many species of bony fish are alive today and what percentage are marine?
About 25,000 species (100 new described every year) of which 60% of species are marine
What 2 groups are Osteichthyes divided into?
. Ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii) e.g. the lungfish and coelacanths
What do all bony fish have?
. Scales
. Gills for respiration
. Cold blooded (ectothermic)
(however some members of the family scombridae e.g. swordfish and tuna have some level of endothermy)
When did Chondrichthyes- cartilaginous fish (Sharks, rays, skates and ghost sharks first appear? How many species are there?
First appeared about 420 million years ago (older than the Osteichthyes). Possibly 1200 species (around 500 sharks and around 609 rays and skates)
Describe Cartilaginous fish
Jawed fish with paired fins, scales (denticles) and skeleton made of cartilage rather than bone. Gills for respiration. No gas bladder (will sink if they stop swimming). Fertilisation is internal. Development is usually live birth (ovoviviparous species) but can be through eggs (oviparous) (internal or external)
What are the 2 subclasses of the class Chondrichthyes?
. Elasmobranchii (sharks, rays and skates-most)
. Holocephali (chimaeras/ ghost sharks-smaller group)
Describe the subclass of the class Chondrichthyes
Around 500 species sharks, ~600 batoids: rays and skates. Have an upper jaw that is not fused to the braincase and desperate slitted gill openings (5-7 gill slits)
Describe the subclass holocephali of the class Chondrichthyes
50 species chimaeras (ghost sharks and ratfishes). Upper jaw fused to the braincase. One gill slit with an operculum cover (4 pairs of gills)
What are elasmobranchs?
They are all marine, apart from one species that go far up in rivers and a few fresh water stingray
(Includes sharks and batoids)
Describe batoids
Skates and rays: they are flat bodied with pectoral fins developed into broad flat wing-like appendages
What is the major difference between skates and rays?
The way in which they reproduce. Rays are viviparous (live bearing) while skates are oviparous (egg laying)
Skates normally have prominent dorsal fins whiles rays dorsal fins are absent or reduced
How do rays reproduce?
Oviparous (egg laying) by releasing their eggs in rectangular cases called ‘mermaid purses’
What are the 5 pelagic zones?
. Epipelagic . Mesopelagic . Bathypelagic . Abyssopelagic . Hadopelagic
Describe the epipelagic zone
Surface to 20. Continental shelf. Lots of light and this is where nearly all production takes place and where most organisms are found
Describe the mesopelagic
200-1000m. Twilight zone. Little light but enough for photosynthesis. Together with epipelagic this is the photic zone
Describe the bathypelagic zone
1000-4000m. Pitch dark. Deepest recorded Chondrichthyans: great lanternshark (Etmopterus princeps) round in depths down to 4500m
What is the Latin name for the lanternshark?
Etmopterus princeps
Describe the abyssopelagic zone
4000-sea floor
Describe the hadopelagic zone
Ocean trenches
What is the basic shark anatomy (shape) known as?
Fusisform
What is the caudal fin?
The tail fin
What have the dorsal fins in rays been modified into and why?
Spines because they lay on the bottom of the sea, so it wouldn’t s far more difficult to take water in
What do spiracles do?
Allow water in (bigger in rays than sharks)
What do nostrils in sharks take in?
Water and chemical sensors
What is the spiracle in sharks associated with? What is it derived from?
The respiratory system
It is derived from one of the gills
What are the paired fins in sharks (the dorsal, pectal and pelvic fins) not attached to?
The vertebral column, they are separate from it (there is no rib cage)
What are the dermal denticles in sharks homologous with?
Structure of teeth
How do most (bony) fish create static lift?
With their swimbladder
What do mark-recapture studies of sharks tell us?
Where the animals are going at different times then can link with tidal movements, temperatures etc.
Why do sharks mature slowly relative to many other fish?
Because they are long lived and don’t need to feed as much as some of the faster growing species
What do boy fish feed on?
Other fishes, carrion, invertebrates, mammals , scales, eyes, eggs and zooplankton
What group are the most advance living bony fish?
Teleosts
What are the only group of fish that utilise plant materials in all its forms?
Teleosts
What group are the only true endoparasitic species?
Teleosts
What do teleosts produce?
Lift and electricity
How many species of living species of teleosts are there?
> 24,000
What is the primary function of fish scales?
For protection
What does the stiff vertebral column in teleosts provide?
Provides compression resistance- body bends side to side rather than shortening
We can identify specialist swimming types however, optimal design for one traits tends to do what?
Reduce ability in others
Are the majority of fishes locomotor generalists or locomotor specialists?
Generalists but many fishes are will switch between nodes (not all fish easily fit into one category)
How do some fish will switch being locomotion generalists or specialists? give an example
Because they may have fins that can be erected or depressed adding a dynamic quality e.g. largemouth bass
