Lecture 10 Flashcards
1
Q
Characteristics of Cambrian Radiation-based on basic body plans
A
- rapid
- primitive members of still living phyla first appear
- few clades basal to two or more phyla
- high disparity, low diversity
- many short-lived lineages
- ancestral vertebrates present, but do not dominate ecology
- most animals are soft bodied but larger skeletonized animals evolve
- good portion of animals not adapted to live on land in this period so they had to change body plans and physiology based on selective pressures `
2
Q
Lobe fin fish
A
- have both gills and lungs
- thought they might have lived in places where oxygen levels were low in the air so they used gills to breathe sometimes and lungs to breathe other times
- fins and lungs are preadaptation to life on land
3
Q
Basal Vertebrates
A
- arise in Cambrian
- jawless fish ~20myr later in Ordovican
- fish with jaws first appear ~30myr after jawless fish in Silurian
- first tetrapods (vertebrates with legs) appear in Late Devonian, 100 my after end of Cambrian
4
Q
Invasion of Land
A
- major environment shift
- very demanding: selection for conserving water
- when you live in water there’s plenty but when you live on land you have to constantly carry this water around because biochemical reactions in your body rely on it to proceed.
5
Q
Ordovician
A
- plants move to live on land
- once plants get on ground, becomes much more attractive for animals to evolve to live on ground
- plants provide food for animals
- algeal near water, liverworts (non-vascular)
6
Q
Silurian
A
- conditions of the ocean before vertebrates have started going ashore
- first vascular plants
- coral reefs prevalent
- some major novelties: eurypterids appear–>giant scorpion-like, aquatic forms up to 9 feet long–>predators
7
Q
Vertebrate evolution leading to conquest of seas and land
A
- Agnatha: jawless vertebrates, poorly developed appendages
- evolution of paired appendages
- evolution of jaws
- advanced fish classes-placoderms, chondrichthyes (sharks), osteichthyes (bony fish), and sarcopterygians (lobe fin fish)
- lobe fins are ancestral the tetrapods (us), and they are the pioneers of vertebrate land life-evolution of lims. These fish have both gills and lungs
8
Q
Selection For these things when invasion of land started
A
- resistance to gravity
- breathing air
- conserving water
- new methods of excretion
- extremes of cold and heat
- internal fertilization/protection of eggs
9
Q
Big players in invasion of land
A
- primitive vascular plants
- vertebrates
- insects
- spiders
10
Q
smaller roles in invasion of land
A
- snails
- annelids
- planarians
- onychophorans
11
Q
Devonian
A
- vascular plants diversify and grow larger
- myriaods
- primitive wingless insects
- scorpions
- primitive spiders
- first tetrpods
- by end, first forests of large trees
12
Q
Archaeopteris
A
- very large trees
- oldest petrified wood
- common around Henryville IN
13
Q
Development of gills
A
- as fish got bigger, gills developed
- increases surface area but doesn’t take up much body space
- very effective means of transferring oxygen and carbon dioxide
14
Q
First land animals
A
-Silurian: arthropods: primitive myriapods; mollusks: snails
15
Q
Some pre-adaptations
A
- i.e. already have features that give some advantage in a new selective regime
- hard body coverings: prevent water loss
- effective means of propulsion (generally legs)
- internal fertilization
- Problems: gas exchange and excretion
16
Q
Gills of Fish
A
- allow them to get rid of toxic ammonia by directly excreting it
- no land animals can excrete just ammonia
- we use urea
- some animals are even better at disposing of ammonia and make uric acid which is insoluble (reptiles, birds) so it is much more water saving
17
Q
Plants moving to land and conducting photosynthesis
A
- current level of oxygen in air is 21% which has been pretty stable
- oxygen level spikes 300-250 mya and very strange creatures arise
- drops drastically to 16% which would be very difficult to breath
- all this happens because plants moved to land and made it habitable to us
18
Q
Methods of gas exchange
A
- oxygen in, carbon dioxide out
- integument
- gills
- lungs with alveoli
- trachea
19
Q
Kidney (in vertebrates) and Malpighian tubules (in insects)
A
- concentration of waste
- recovery of salt
- saves water
- responsible for modifying biochemistry to a less toxic nitrogen waste–>urea in amphibians, mammals and some reptiles
20
Q
Devonian-Permian
A
- land plants, first forests, massive photosynthesis
- C02 levels fall, organic carbon buried as coal, O2 rises
- vertebrates can come to land and first land-laid egg
- age of giant insects
21
Q
Insects
A
- crucial players on land
- have primitive arthropod ancestor in common with crustaceans, millipedes and centipedes and chelicerates (spiders)
- most diverse arthropods and seem to have evolved on land
22
Q
Insect relationships
A
-Apterygota (silverfish), Paleoptera (dragonflies) and neoptera (butterflies and house flies and bees) all have a common ancestor
23
Q
Origin of insects
A
- had an aquatic ancestor that moved to land
- required a transformation of aquatic leg to a terrestrial one and a new means of breathing
- marine ancestor likely had gills on legs
- ancient insects: trachea on land as adult, gills on aquatic larvae
- very first insects were wingless
24
Q
Origins of wings
A
-apparently evolved from wing-like gills of aquatic insect larvae
25
Q
Crustacean and Trilobite limbs
A
- biramous limb
- trilobite had filamentons branch
26
Q
Insect limb
A
-uniramons limb
27
Q
Evolutionary trends in early insect evolution
A
- wingless
- loss of exopodite of aquatic ancestors, evolution of trachea
- legs on all segments: lost on abdomen but converted to mouth parts on head
- reach very large sizes because of high oxygen levels and no competition from flying vertebrates
28
Q
Why were vertebrates good on land?
A
- nerve cord (dorsal)
- vertebral column (built around notochord)
- circulatory cord/system (ventral heart)
- segmentation
- paired appendages
- somites=paired groups of body wall muscles
- hydroxy apatite (bone) skeleton
29
Q
Vertebral column
A
- provides different function for swimming fish than for walking tetrapods
- allows fish to swim like they do
- tail fin swims side to side which is controlled by muscles along the body wall that are tied to the skeleton
- skeleton doesn’t have to support the weight of walking
30
Q
fish lungs
A
- retained in tetrapods
- converted to swim bladders in teleosts
31
Q
Amphibians
A
- gas exchange via skin and lungs-not water tight
- major steps and preadaptations: lungs (preadaptation), legs (from lobe fin), vertebral column (support of body on land)
32
Q
Eusthenopteron, Ichthyostega, and advanced Labrinthodont
A
-look at this page
33
Q
Amphibian reproduction
A
- aquatic egg, development of fish-like tadpole
- gills
- ammonia excretion
- swims with tail
- metamorphosis from tadpole to frog
34
Q
Origin of reptiles
A
- carboniferous
- skeletons of first reptiles very similar to amphibians
- amazing novel evolutionary event–>new mode of development
- freed themselves from dependence on water–>lay eggs or have live births, invent internal fertilization
35
Q
Revolution in conquest of land by vertebrates
A
- water tight skin
- better limbs
- better sense organs
- free from return to water for reproduction
- amniotic egg (look at drawing)
36
Q
What’s an egg?
A
- yolk sac: has nutrients
- waste sac called _____
- amniotic cavity: where embryo develops
