Phylogeny and diversity - Part 1 Flashcards
What is the difference between extinct and extant species?
Extinct species are dead.
Extant species are currently living.
Why do we care about extinct species?
Some of the extinct groups existed for longer than we have.
They laid down the foundation for what we see in extant species.
Fish vs. fishes.
Both are plural.
Fish - when talking about multiple individuals of the same species.
Fishes - if talking about lots of different fish species.
What are chordates.
At some point in development had a notochord, dorsal hollow nerve cord, pharynx with slits, postanal tail and myomeres for locomotion.
Is a hagfish a fish?
Why is there debate?
Yes.
It is not a vertebrate but it is indeed a chordate.
What are the different fish groups?
Ostracoderms, Hagfish, Lampreys, Placoderms, Chondricthyes, Osteichtyes - Sarcopterygii - Actinopterygii HOLP COsa
Describe ostracoderms.
Extinct
Important for a few reasons:
1 - probably gave rise to the current, bony fishes
2 - first animal to develop true bone as external armour
3 - major evolutionary advance, filter feeders
Describe hagfish.
Fish, extant, no bone just cartilage Evolutionary option that didnt lead to anything 6 separate hearts Osmoconformer Scavengers
Describe lampreys.
Extant
Been here for a while, didnt lead to anything
No bone but has a vertebral column
Which groups are part of the Agnathans classification? What does this mean?
Jawless fish HOL Hagfish Ostracoderms Lampreys (most likely a monophyletic grouping)
What do the other groups fall under? What does this mean?
Gnathostomes - not a phylogenetic lumping like Agnathans Jawed fish P COsa Placoderms Chondricthyes Osteicthyes - (sarcopterygii) - (actinopterygii)
Describe placoderms.
Extinct major predator in their time true bone of ostracoderms was probably a defense against these guys fully movable jaws very diverse/speciose didnt lead to anything evolutionarily may be related to sharks most common fossil
Describe condricthyes.
Sharks and rays Cartilaginous, no bone Two separate subgroups - sharks and rays - chimera True class, all related phylogenetically
What does Osteichthyes mean?
true bony fish
Describe Osteichthyes
True bone in the skeleton first to evolve bony skeletal support True class two subclasses - Sarcopterygii - Actinopterygii
Describe sarcopterygii.
Gave rise to tetrapods
lobe-finned (muscular and skeletal support in fin)
bony fish
extant
Describe actinopterygii.
Most fish
ray finned
skeletal support in body (not in fin)
probably led to diversification of multiple species
What are the advantages of ray fins?
More flexible, allow good swim control and maneuverability
Where did the first fish come from?
Conodonts - cone-tooth
first proto-fish
Conodont was probably a _____-_____. (how it eats)
filter-feeder
Why do we only care about the Devonian Age?
age of fishes
before this, probably had conodonts becoming fish
at the end of the devonian, all the major groups of fish had evolved
at the end of the devonian, started seeing tetrapods
What drove fish diversification?
Evolution of land plants.
Describe how the evolution of land plants could have led to the diversification of fish.
Increased productivity brought about by land plants drove fish to move to coastal water, opening up new habitats and driving diversification.
What are the key characters needed to become a tetrapod?
1 - Evolution of a neck
2 - Dorsal eyes
3 - enhanced rib cage
Describe roughly what the first proto-tetrapod characteristics would have been.
Lived in water, respired by gills, didnt have lungs, still had scales, had fins.
What was new was the neck, dorsal eyes and heavy ribs.
What was most likely the first proto-tetrapod?
Tiktaalik
What were the key benefits for the neck for Tiktaalik?
No longer had an operculum but a neck, could look left and right and scan the evnironment for food/predators while swimming ahead.
What were the key benefits of dorsal eyes for Tiktaalik?
Since it now lives in shallow water, wants to eat prey, mainly inverts above it, allows it to find them.
What were the key benefits of a heavy rib cage for Tiktaalik.
Needed to support itself using its lobed-fins in shallow water with head outside the water scanning the environment.
Lots of pressure on the chest. Gravity acts on the organs.
Heavier pectoral girdle protected its internal organs during its scavenging activities.
What are some of the environmental drivers for tiktaalik progressing to tetrapods?
Shallow coastal waters are productive, safe from predators, lots of insects present.
Describe the experiment to provide evidence for the transition towards land using Bichir.
Took Sarcopterygian fish called Bichir and applied different selective pressures.
Bichir is similar in skeletal morphology to first tetrapod.
Compared those raised on land vs. those raised in water.
Found changes in behaviour and anatomy, similar to those in tiktaalik.
The same bones found in the fins of sarcopterygian fish evolved into what?
tetrapod limbs
How is limb development similar in sarcopterygian fish to us?
Patterns of expression of Hox genes are very similar and conserved.
- same genes are turned on when making the mammalian humerus as when making the lobed find bone
Limb bones are also conserved evolutionarily
(Fossil evidence and gene expression data to show that tetrapod limbs came from skeletal elements of lobe finned fish)
Patterns of ___ gene expression is similar between _______ and __________.
Hox
Tetrapods
Sarcopterygians
What is the selective advantage of true vertebrae?
Protect the spinal cord More mobility Stronger Allows better muscular attachment - a lot of swimming is generate by muscles anchored to the vertebrae
What is the evolutionary advantage of jaws?
Consume more resources
Can have different prey types
Can eat plants
Diet specialization
What is the evolutionary advantage of paired fins?
Maneuverability in tight places
steering and balance
As anchors
dont have to strictly swim straight anymore
opened up new habitats and allows better escape from predators
What is the evolutionary advantage of an operculum?
Protects gills Acts like a pump to aid in respiration Forces water to flow in one direction Allows for breathing without needing to swim allows two pump respiratory system
What is the evolutionary advantage of branchiostegal rays?
supports the membranes
increases water pumping efficiency by allowing pump size to increase (opercular cavity) through ray contraction/relaxation
What is the evolutionary advantage of lepidotrichia?
Greater maneuverability
Allows fine scale control of stopping, starting and turning when swimming
What is the evolutionary advantage of pleural ribs?
Protects internal organs
Thick
What is the evolutionary advantage of tooth enamel?
Protects and strengthens teeth
Prevents them from getting cold
can chew food, eat harder food, serration of food types
What is the evolutionary advantage of lobed fins?
Support more weight and more motion
support off substrate
Fine scale movements with a heavy support
can support weight out of water
What is the evolutionary advantage of choana?
Can sniff underwater
Can breathe when the mouth is shut
Better olfaction
Can eat larger meals without having to stop and breathe
