exam 1 Flashcards
Diagnostic characteristic
trait shared by all birds, but no other LIVING organisms
Unifying characteristics
- reflect a common evolutionary history
- shared by all birds
- other organsims may also share these traits
Evolution
species have changed over time and are related by descent from a common ancestor
Name a diagnostic characteristic of birds
feathers
Name at least 5 unifying characteristics of birds
1, Bills
2. Skeletal specializations - pneumatic bones, fusion/reduction of bones
3. Bipedalism - digitagrade feet (walk on toes)
4. centralized body mass for flight and balanced walk on land
5. High metabolism
6. specialized circulatory and respiratory systems
7. highly developed CNS and vision
8. large, nutrient rich eggs
9. loss of urinary bladder
10. Loss of teeth (replaced by gizzard)
Natural selection
individuals that survive to reproduce will have higher fitness
Adaptive radiation
process in which organisms diversify rapidly from an ancestral species into a multitude of new forms that fill new ecological niches
ex) galapagos finches diversified their bill shapes to fill new niches
convergent evolution
evolution of shared characers due to similar ecological pressures NOT common ancestry (traits are analagous not homologous)
Phylogeny
the evolutionary history of an organism
Systematics
the field of study that seeks to reconstruct phylogenies
Phyletic evolution
gradual change in a single lineage
speciation
splitting of a single phyletic lineage into two or more
extinction
termination of a lineage
Biological species concept
a group of interbreeding or potentially interbreeding populations that are reproductively isolated from other groups
Phenetics
organisms are grouped based on overall similarity without regard to evolutionary history
Cladistics
some traits are more useful than others in determining relationships, particularly shared, derived traits
Phylogeny
an evolutionary history of a group of taxa described as an evolutionary tree (cladogram) with a common ancestor at the base and descendent taxa at the branch tips
The word ‘taxa’ can describe
a population, subspecies, species or genera
What types of characters should you chose in cladistics?
homologous characters (show the clearest evolutionary relationships)
Homologous trait
a trait that is derived from a common ancestral trait
Analagous trait
does not show an evolutionary relationship between two animals - appears similar due to convergent evolution
ex) bird wing and insect wing
Synapomorphy
shared, derived traits - define a monophyletic group
Symplesiomorphies
shared among all taxa in a phylogeny due to its evolution in a common ancestor
ex) in birds, this might be feathers
Homoplasies
are analagous traits OR reversals
What type of traits are the most useful for classifying high level taxonomic categories?
conserved characteristics
Name some conserved characteristics that can help determine taxonomy in birds
- bony palate - separates paleognathae from neognathae
- nares
- structure of leg and foot muscles
- morphology of vocal apparatus
- behavior
- vocalizations
- downy chick plumage
- toe arrangement
Parsimony
the principle that the most likely explanation is the simplest one - the cladogram that is most likely to be closest to reality is the one with the fewest transitions (losses/gains of traits)
this is based on the assumption that synapomorphies are more common than homoplasies
Monophyletic group
includes the most recent common ancestor of a group of organisms and ALL OF ITS DESCENDANTS
polyphyletic group
does not include the common ancestor of all members of the taxon
paraphyletic group
includes the most recent common ancestor, but not every descendant
Reptiles and birds describe this type of phylogenetic group
monophyletic group
reptiles describe this type of phylogenetic group
paraphyletic group
warm blooded animals (mammals/birds) describes this type of phylogenetic group?
polyphyletic group
Name some steps in the evolution of modern birds
- reversed hallux - grasping or perching foot
- tarsometatarsus - fused leg bones
- carpometacarpus - fused wrist and hand bones
- pygostyle - shortened tail vertebrae/fusion of bones
- keeled sternum - attachment of flight muscles
- modern coracoid - modified shoulder joint allows movement of wing above head
- alula - facilitates flight by reducing turbulence, esp. during slow flight
This group of birds that occured ‘after archaeopteryx’ is now extinct
Enantiornithine birds
What are some characteristics of Enantiornithines? (6)
- most abundant and diverse group of avialans in the cretaceous period
- additional modifications for flight
- modern perching foot
- advanced forelimb modifications (raise wings over body and fold them)
- retained teeth and clawed fingers on each wing
- NOT ancestors of modern birds
Name some characteristics of ornithurae birds (2)
- uncinate processes connect ribs and protect thoracic cavity
- loss of teeth
Name 2 branches of extinct ornithurae birds
- Hesperornithiformes - toothed diving birds with larged lobed feet
- Ichthyornithiformes - flying toothed seabirds - like terns
Name the ancestors of modern orders that survived the mass extinction (2)
- Paleognathae - ratites/tinamous
- Neognathae
- Galloanserae (Galliformes - turkey and quail + Anseriformes - ducks)
- Neoaves (procellariiformes - petrels and albatross + shorebirds - sandpipers and plovers)
Feathers
unique epidermal structure composed of a special class of beta-keratins
Types of feathers (7)
- contour feathers
- flight feathers
- down
- semiplumes
- filoplumes
- bristles
- powderdowns
Name the two types of vaned feathers
- contour feathers
- flight feathers
Calamus
the bare part of the feather where it attaches to the bird
Vane
the part of the feather that is connected to the rachis
Pennaceous structure
interlocking barbs
Barb
the part of the feather that branches from the rachis, including the ramus, barbule and barbicel
What is the relationship between the barbule and barbicel
barbicels are hooklike structures that protrude from the barbules
What are some characteristics of contour feathers
- feathers that cover the body and wings
- may have an aftershaft
- symmetrical vanes
What are the 2 types of wing feathers
- primaries attach to the bones of the hand and second digit (fused)
- primaries are numbered starting at ten (X) on the leading edge all the way down to 1 - BIRDS ONLY HAVE 10 PRIMARIES - secondaries - number of secondaries may vary from like 8 to 35 and are numbered in the opposite direction from the primaries (increasing in number towards the body)
Coverts
- cover calami of remiges
- help body be more aerodynamic
- overlap like shingles on a roof
- flight feathers mostly hidden on closed wing
Why are flight feathers asymmetrical?
the leading edge of the feather has a narrow vane to increase stiffness and rigidity and provide lift
flight feathers with coverts combine to make the entire shape of the wing an assymetrical, curved structure to facilitate lift
How are the remiges numbered?
Primaries are numbered 1-10 with 10 being the most distal and 1 being the most proximal
Secondaries are numbered 1-n with 1 being the most distal and n being the most proximal
What are the remiges
Wing feathers
What are the retrices?
Tail feathers
How are the retrices attached?
Attached via ligaments to the pygostyle
Are the retrices pennaceous or plumulaceous?
Pennaceous
Name the 2 types of pennaceous feathers
- Flight feathers (retrices/remiges)
- Contour feathers
What is the function of the retrices?
Steering and landing
Can disrupt airflow to decelerate, or spread/narrow/tilt tail to steer
What are the characteristics of a down feather?
No central rachis
Barbules lack barbicels
Plumulaceous
Thermoregulatory function
Reduced or absent rachis
Natal down
Occurs in young birds, grows in feather tracts and is eventually replaced with contour feathers
Adult down
Occurs all over the body, not just in tracts
What are some characteristics of a semiplume?
-No barbicels
-Plumulaceous
-Traps air (thermoregulatory fct)
-The rachis is longer than the longest barb - KEY CHARACTERISTIC
What are some characteristics of a filoplume?
-Sensory feather with tuft at the tip of the feather
-hairlike
-touch receptors in the skin next to the feather
-fct theorized to be detecting wind speed and direction
What are some characteristics of a bristle?
-sensory feather with tuft at the base
-occur around eyes and bills
-connected to sensory corpuscule at the base
-tactile and protective function (like eyelashes)
Ramus
-the main part of the barb
-barbules attach to the ramus, which extends perpendicular to the rachis
What is the function of rictal bristles?
To funnel food towards the mouth and to compensate for reduced vision when feeding at night
What is unique about the feathers of a sandgrouse?
Males soak up water for chicks to drink out of his belly feathers - like a sponge
What is unique about the feathers of club winged manakins?
They rub their wings together to create sounds and court females