Studied by 7 peopleAmphibia, Reptilia, Mammalia, Aves
Four Linnean classes of terrestrial vertebrate
Draw the phylogeny of Tetrapod groups
Testudinoida, Crocodilia, Lepidosauria
These three tetrapod groups are considered reptilia
Amphibians and Reptiles
The tetrapod group called Herps, contains these two groups.
Aves
The reptile clade technically includes 4 groups. Which of them is not considered reptilian?
carboniferous
A period where large vascular plannts arose. It was characterized by coal swamps.
Phenotypic similarities
phylogenetic systematics
The Two main approaches to taxonomy
Parsimony
Principle used to maximize likelihood in phylogenies
Cladistics (maximum parsimony)
Molecular phylogenetics (DNA analysis)
Methods used to create phylogenies.
Fossils Traits of extant spp. DNA and other molecular markers
Modern taxonomical methods
375 million years ago
How long ago did tetrapods invade land?
The north american breeding bird survey. Conducted in early summer, with many 24.5 mile long routes. Stops every 0.5 miles where a three minute point count is done on every bird seen or heard within 0.25 miles. Takes 5 hours to complete. (this is a transect)
What is BBS. How is it conducted?
The Christmas Bird Count.
Conducted via people completely censusing a 15 mile diameter circle in teams. Each team is assigned a route within the circle.
What is CBC? How is it conducted?
408-360 million years ago
375 million years ago the first tetrapods invaded land.
how long ago was the Devonian? What is significant about this period?
438-408 million years ago
When was the silurian period?
During the early devonian there were smaller vascular plants, by the late there were larger vascular plants; fern forests and gilboa trees.
Describe the development of vascular plants, when did this happen?
First appeared in the silurian and devonian, diversified in the carboniferous.
When did insects first appear and when did they diversify?
Movement between ponds: Escape drying ponds Escape predators Juvenile dispersal (avoid interbreeding)
Benefits of land: New niches to occupy No predators No competitors initially
list some theories on selective forces regarding terrestrial invasion
New means of gas exchange Locomotion Stronger skeleton Metamorphosis (aquatic larval stages due to reliance on reproduction in aquatic habitats)
List some adaptations requried to move on land from water
A fish. Lots of modern fish have lung like organs
What kind of organism first developed lungs?
Actinopterygian (ray-finned) Sarcopterygian (fleshy/lobe finned)
2 major groups of fish
Acanthostega Gunnari Discovered in Greenland in 1987.
Note that it was alive in late devonian (360 MYA!!!)
An early aquatic tetrapod fossil from the late Devonian. (360MYA). Where was it discovered?
Tiktaalik Roseae Discovered in Canada in 2006.
Exhibits traits that would suggest it was a transition from sarcopterygian fish to tetrapods
Would have been around some time in the devonian, before acanthostega gunnari
The link between fish and land vertebrates. (fossil) Where was it discovered? What is significant about it?
Carboniferous (360-286 MYA) and permian (286-245 MYA)
During which period of time did tetrapods diversify?
Temnospondyls
A speciose group of amphibians from the paleozoic; the ancestors of all modern amphibians.
A group of amphibians from teh paleozoic. This group contains the ancestors of all modern amphibians.
What are temnospondyls.
It exhibited paedomorphosis. Also likely the sister group to all modern amphibians.
What was notable about the branchiosaurus?
Gymnophiona: caecilian
Caudata: Salamanders
Anura: Frogs and toads
originated in the Permian (286-245 MYA)
Groups of modern amphibians. When did they originate?
Permian mass extinction
When did a lot of early lineages go extinct?
Amniota
What is the other major group that survived the permian (besides amphibians)
They have several membranes that facilitate reproduction away from water. Evolved to allow terrestrial reproduction.
What is notable about amniotic eggs?
During the permian (286-245 MYA)
They had traits that allowed them to be more successful; more successful reproduction away from water, stronger jaws and teeth allowed them to tear at prey. DIVERSIFICATION OF FOOD SOURCES
When and why did early amniotes (reptiles) diversify and replace amphians?
Therapsids
A group of mammal like reptiles. Bone structure similar to mammalian predators.
Synapsida
A group that is considered ancestral to mammals. The name refers to them having a single Temporal fenestra.
Anapsids
turtles
Lack temporal fenestrae
Diapsids
"reptiles"
lepidosauria
aves
crocodilia
organisms with two temporal fenestrae
temnospondyls and Amniotes
245 million years ago!!!!
Which group ssurvived the permian extinction? When did the permian mass extinction happen????
Reptilian amniotes (synapsids???)
What were the ancestors to mammals?
Squamata
Order that contains lizards and snakes.
Chelonia
Order that contains turtles
Sphenodontida Tuatara
Order containing a single extant lizard-like species. What is the species
Serpentes (snakes) Lacertilia (lizards) Amphisbaenia (worm lizards)
3 major groups within squamata
Ornithiscian dinosaurs
Sauriscian dinosaurs
birds developed from sauriscian dinosaurs
Two groups of dinosaurs. Which one did birds develop from?
Archosauria
name for group containing crocodilia and aves
sauropsida
Group containing testudinata, crocodilia, aves, and lepidosauria
Diapsida
Group containing aves, crocodilia, and lepidosauria
archaeopteryx
150 MYA (late Jurassic)
First bird fossil. how long ago did it live?
flight muscle insertions require large surface area to attach. Archaeopteryx likely didn't have these developed flight muscles.
why do modern birds need a large keel. Why did archaeopteryx lack it?
Assymetrical feathers are typically used for flight which suggests archaepteryx may have been able to fly or glide. May have even just been a means of lift generation for walking up inclines or running
Archaeopteryx had assymetrical feathers. Why is this notable?
Strong keel Hollow bones feathers pygosyle supports tail feathers hand bones fused to strengthen wing.
Bill replaces heavy teeth.
List some Flight adaptations
Theropod or thecodont dinosaurs
Theropods are a group within the thecodonts
Thecodont (Triassic)
Therapod (late jurassic)
What are the two potential groups archaeopteryx evolved from? When would this have taken place for each group?
Therapod origin
Recent findings support which theory of bird origin?
Protarchtaeopteryx
Caudipteryx
Two fossils that support the theropod theory of bird origin
The pubis and ischium are parallel to one another. this is similar to the pelvis in modern birds, which lead scientists to believe birds may have developed from ornithiscian dinosaurs initially. Sauriscians have their pubis and ischium at an angle; However, other sauriscian traits (specifically in therapods) are more similar to birds than other ornithischian traits. The pelvis alone was misleading.
What is notable about the pelvis of ornithiscian birds. Why did this cause confusion about bird origin?
Microraptor gui
A fossil with four feathered limbs
Structure of melanosomes
How is fossil color inferred from fossils?
Feathers originally for warmth and display. Eventually developed enough feathers that they could generate lift while running. Selective forces acted on the birds ability to generate lift over time; eventually leading to flight.
Wing assisted running; can be used to run up inclines in birds. Suggests initial selection pressure may have been to push organisms towards the ground to move up inclines.
Explain the ground up origin of flight theory (Cursorial)
Birds initially use feathers to glide from tree to tree; eventaully developed flight.
Many arboreal vertebrates have developed gliding; none of them are known to have developed it from the ground up; this is an argument for the tree-down theory.
Explain the tree down origin of flight theory (arboreal)
Cretaceous (65-66MYA) or Tertiary(less than 65MYA).
IE: did birds diversify before the dinosaur mass extinction (which happened 66 MYA) or after it.
When did major groups of modern birds evolve? 2 potential theories?
modern birds diversified following the cretaceous-tertiary boundary. IE: following the mass extinction
Supported by DNA evidence: genome-scale DNA phylogeny of birds
What is the post extinction big bang diversification model? What is the evidence for it.
Suggests that modern birds diversified before the mass extinction.
Little supporting evidence due to lack of fossils
What is the Cretaceous diversification model. What evidence is there for it.
Neognathae paleognathae Galloanseres
what are the three groups of birds that survived mass extinction?
unidirectional air flow, cross current gas transfer
What kind of airflow and gas transfer do bird lungs have?
To allow them to make deeper pitched sounds; which is useful for sexual selection (females like deep voices ;)
Why might some birds have convoluted, long tracheas?
It describes the probability that two randomly selected individuals from a given site are different species.
Higher number= higher probability= more diversity
Ranges from 0->1
0= all same species
1= not possible since it would imply that you could never pick two of the same species in a row
Explain Simpson's diversity index
2a/2a+b+c
Essentially measures the proportion of total seen species that are shared across the two sites.
A= shared species B= only at site 1 C= only at site 2
This is somewhat sensitive to sample size
Explain Sorenson's similarity coefficient
Essentially measures the proportion of individuals that are shared across the sites; taking relative abundance into account.
For both sites; the proportion of individuals that are a given species is calculated. The lower numbers are selected for each species and added together. This results in some number (less than 1) that represents the proportion of either population that is shared with the other population.
Ex: 10 total individuals at both sites. At site 1 we have 3 Pacific Wrens, at site 2 we have 5. So we calculate the proportions of pacific wren as 0.3 and 0.5. Since 0.3 is lower we use that one. We repeat for all bird species observed and add up the resulting numbers.
Explain the Rankonen index (percentage similarity)
Biological species concept:
derived from mendel's work and ultimately provided a new way to distinguish species besides morphology.
What concept lead to the reduction in bird species around the early 1900s?
"a species is any group of actually or potenitally interbreeding natural populations that are reproductively isolated"
problems: Asexual species how much hybridization is enough allopatry may prevent us from grouping together otherwise compatible species
Describe the Biological species concept; What are some problems with it
Speciation
Results in increased: reproductive isolation phenotypic, genetic, and ecological differences
The process by which one species develops into two; what increases during this process
A single population is split and geographically isolated; this results in differentiation of the two populations until they are inherently less compatible with one another; either pre or post-mating isolation develops
Describe the allopatric model of speciation
Individuals within a given population differentiate enough that they are reproductively isolated from the rest of the population without changing locations or being geographically isolated.
Describe the sympatric model of speciation
For a given species; its closest relative is often found nearby;
never in the same place
never really far away
This suggests that these species may have been geographically isolated from one another and allopatrically speciated.
How does the biogeographic pattern support speciation?
Suture zones
Places where divergent biota meet are called...
Following the ice age, eastern ice melted earlier; allowing for the expansion of forests (refugia) northwards through Canada to Alaska. Around British Columbia where the ice melted later, the forests were unable to expand north. The eastern birds essentially followed their native forests up into northern canada and to the alaskan coast thanks to the earlier melting of eastern ice.
Why are some eastern American forms of birds found in alaska
It allows us to see the effects of generations of allopatric speciation in birds.
Significance of the great candian sulture zone
Hybrid zone theory explains the formation of hybrid zones as places where two species com into contact with lower net reproduction. Hybrid zones remain narrow via subtly lower fitness of hybrids that reduces net reproduction within the contact zone; this results net gene flow into the hybrid zone rather than out= zone stays narrow. More reproductive isolation= narrower zone. We can use the width of hybrid zones to therefore assess how isolated two forms/species are.
Explain hybrid zone theory
Genes that are not under divergent selection can still be passed over from one species to the next. Species can still maintain their differences despite this gene flow.
Why can different species still share genes?
A hybrid zone with a stable balance of gene flow into the zone and selection against hybrids.
What is a tension zone?
DNA evidence showed that over 90% of bird species exhibit extra pair copulation/paternity. IE: birds are rarely monogamous
What did DNA evidence reveal about bird mating?
Extra pair copulations
What does EPC stand for
Extra pair paternity
What does EPP stand for
This allows females to hedge their bets in terms of having offspring with higher quality genetics and more genetic variation. IE: greater chance of offspring surviving.
Dominant males get to propogate their genes a lot through many females and many offspring
Subordinate males are able to reproduce as well at a lower rate than dominant ones
Why might females mate with multiple males; does this have any benefits for the males as well?
Social monogamy
Polygyny
Polyandry
Polygynandry
List the avian mating systems
Single male single female nests; very uncommon
Example: penguins, albatrosses
Dunnock's were originally thought to be monogamous but that is not the case
Explain Social monogamy; give an example bird
One male; multiple females
Example: Sage grouse, red winged blackbird
Explain polygyny
one female; multiple males
Example; phalaropes
Explain polyandry
Anything goes; multiple males multiple females
Example: acorn woodpecker
Explain polygynandry
Cooperative breeding; polygynandry
Individuals work together to raise young in an extended family
helping related individuals survive essentially promotes one's own genes.
some inbreeding
kin selection
gain experience
Explain the benefit of acorn woodpecker breeding
Opportunistic: females have their own nests; but they may lay eggs in other nests if they must
Obligate; females do not have their own nests. Only lay their eggs in other birds' nests.
2 types of brood parasitism; explain them
It would be disadvantageous if the females mistook their own eggs for intruders; IE: safer to just raise all the eggs
Why might hosts not recognize intruder eggs in their nests?
Manakins: perform a dance
Sage grouse: inflate their air sacs to present to females
Bowerbirds; build structures to entice mates.
Give some examples of birds that engage in intersexual selection
Songs are more complex and longer; they are typically done by males to attract mates or establish territory. often learned
Calls are short, simple, and usually innate. Done by both sexes; used to keep the flock together, alarm others, etc
What's the difference between a song and a call?
Some suboscines parrots some hummingbirds Oscines
Which groups of birds are capable of learning and repeating songs?
The signal is called a cue if heard by an eaves dropper. When the reciever benefits from the signal but the sender does not, it is called eavesdropping. Eaves droppers may be predators for example.
In sound communication what is an eavesdropper? What is the signal called in this case?
Dishonest.
This may be done to mislead the reciever for example.
When a sender benefits but the reciever does not what is the sender called?
A fourier analysis involves breaking down a complex wave into the sum of several pure sine waves. This can be used to analyze a given complex wave
What is a Fourier analysis?
Waves larger than a given object will pass through the object. Waves smaller than that object will deflect off of the object. (based on wavelength) (lower wavelength= higher freq=higher pitch)
Birds can only make sound waves smaller than their own body length. They simply cannot propagate waves larger than their own body outside of their body as the waves will simply flow around the bird itself.
Why do small birds make higher pitched sounds than larger birds?
Lower frequency sound is more likely to pass through obstacles and reach you.
If you are in a forest; will you hear a low frequency sound or high frequency sound further away from the source?
In the early morning, the ground is still relatively cool; so there is hot air above the cold air on the ground. Sound waves travel faster in hot air, this causes sound to bend/refract through hot air. In the early morning, this results in an alternative path for the birds sounds to travel up and over to the listener. Ultimately this amplifies the bird's song.
Why do birds sing so much in the early morning?
Note
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