second midterm Flashcards
remember to go move the initial taxonomy slides here!
ok
DNA hybridization - what happens?
-Heat DNA gently
- H bonds break and DNA becomes single stranded
- Cool, and DNA reforms double helices
- related DNA samples will reform strands at a higher temp
- more distantly related samples will reform at a lower temp.
What was Sibley and Ahlquist Taxonomy?
80s and 90s process of performing DNA hybridizations to determine taxonomy on birds
- more precise than electrophoresis
Main difference between traditional and molecular phylogeny
traditional - classical results supported from DNA length variation
Molecular - sequencing approach shows different patterns together - measures a much broader perspective - patterns in DNA more observable
When is it better to establish a territory, and when is it better to roam in flocks?
If resources are uniformly spread out across the habitat it is better to establish a territitory if resources are clustered then its better to be a flock
What is the advantage of flocking in a patchy resource landscape
everyone gets food - more eyes to find the limited resources
Why do the territory owners often win?
they know the territory better than others
How do birds obtain dominance
nicer feathers / bolder colors
larger body size
fighting eachother
status signals - plumage, size, song repertoire, time spent on territory
why will some birds delay changing into male breeding plumage?
not worth having bright colors when you are still too young to find a mate as older males are preferred - energy expensive and a predation risk
- also stops breeding males from fighting with weaker birds
- maximizes resources and minimizes work
Is the cost of intrusion high?
yes, the territory holder has more informaiton about that territory that the invader does not have
What is the relationship between territories and population regulaiton?
- territory size will evolve to match normal conditions
- with high resources territory size only contracts a little bit
- territory size may limit the number of breeding pairs in an area
- but often lots of floating non breeding birds in that area
- so territories do affect populations but in a round about way
- the population is breeding and non breeding birds
- the territory is breeding only
Advantages of flocking for foraging?
find food faster
find food better if temporally variable
increase efficiency
reduce variation in daily food intake - more consistent feeding
- make prey easier to catch if a carnivore
- social learning in pigeons
- information centers
- predation avoidence
How do some flocks act as information centers?
flocks of snow geese, upon arriving in a new area - will all split apart and forage in different directions but by the third day they will all forage the same direction - sharing information on the best place to forage - able to do this very quickly upon arriving to a new placwe
Two kinds of predator detection?
- passive detection - alarm calls
- active detection - mobbing - ganging up on predator
Why are flock sizes limited by benefit?
increasing the number of individuals does not icnrease the benefit
- larger flocks deplete food faster
- predator success goes down with increased numbers - to a point and then will increase when flock becomes too obvious
what is the advantage of having a pecking order within the flock?
all individuals want to be in the best position within the flock - but that will cause infighting
- advantageous to minimize fighting for position
- pecking order reduces conflict
- status signalling works as a mechanism to reduce conflict
- may be shown by plumage
- may explain amount of different juvenile plumages in gulls - establishes order
What if resource constraints suggest you be territorial but predations pressures suggest a flock?
mixed species flocks - team up with birds that dont eat exactly what you eat
common in tropics
common in winter - less food and dont need to breed
Two types of species in mixed flocks?
- nuclear species - birght coloured species that warn and attract predators
- attendant species take advantage of this
Optimal foraging theory
animals need to decide where to forage, how long to stay in a good place, which foods to eat among those available
- optimal foraging theory predicts that foragers will pick the strategy that maximizes fitness
- buttttt birds dont make decisions?
have to optimzr energy present from food minus energy required to obtain it
basic equation for optimal foraging theory?
profit = energy gain - energy cost / foraging time
why may basing optimal foraging models on energy be a problem?
- energy is not the only component of food
- have to worry about other nutrients than simply energy in energy out
- handling component
generalists vs specialists in foraging?
generalists - often searchers who spend more time looking then are more general in what they use - the type or size of food - magpies
specialists - often can find prey easily but must pursue it, so balance cost of pursuit and capture with benefit of prey - hummingbirds - raptors
Where to feed? Marginal value theorm
- food is often distributed in patches
- at first food is plentiful
– becomes depleted – when should the bird seek another patch?
Depends on
-distance to next patch
- chance of finding another patch
- competition
- risk
energy gain will start to level off after a set amount of time in the patch - bird will leave at giving up density - where it determined there is not enough food available and leaves
central place foraging
foraging while returning to a central place - like a nest
- have to determine optimal distance - further leaving will result in a longer trip back
- how much food can be carried? how does food weight affect flight? how much food can the nest handle
- optimal load size depends on distance travelled
What are some problems with optimal foraging models?
- foragers need to know what the best choice is but cant actually do that without sampling other places - which is a non optimal behaviour
- energy focus is limiting - may need to worry about nutrients too
- some foods may be distasteful or have toxic chemicals that affect their use
- forager may be doing suboptimal foraging to avoid predation
- if food is abundant is there a need to optimize
short term general adaptations to extremes
fat storage - in abdomen - 2 days small bird and vulture 17 days - means it takes vultures much longer to put on the same amount of fat - means vultures are less adapted to cold than smaller birds
- change foraging time or diet
Types of adaptations and types of environments?
Morphological - cant change rapidly
Physiological - more flexible
Behavioural - very flexible
Cold
Hot
Arid
Adaptations to cold
Morphological - feathers, coloration, area of bare skin
Physiological - temp regulation, countercurrent flow to extremeties
Behavioural - posture, roosting microenvironment, communal roosting
Morphological adaptations to cold
- more body feathers / body area - 11% compared to 6%
- darker plumages - saves 23% if no wind
- reduced exposure of bare areas
- larger body size in colder climates
Physiological adaptation to cold
maintain high body temperature
- store fat daily - 15-20%
- shiver to create heat
- fill crop at dusk to be able to eat late at night
- goldfinches can stay at 40C in a -70C environment for 8 hours
- some birds do nocturnal hypothermia - drop body temp while sleeping to save energy - but requires some fat to be able to shiver and warm up in the morning
- torpor in humming birds
- some birds can hibernate
- countercurrent blood flow
behavioral adaptations to cold
find warmer microclimates - boxes nests etc
- communal roosting
- puff up
- southern range limit of grouse due to snow cover - they bury in snow to keep warm
morphological adaptations to heat
- fewer feathers / body area
- more exposed areas with lots of blood vessels
- long extremeties
- black plumage
- more blood to feet
Physiological adaptations to heat
panting
- gular flutter - another avenue for evaporative heat loss - advanced panting - 1.8 compared to 3.5
- loss thru skin
- rete for hyperthermia for brain - using cool veinous blood moving thru bill to lower temperature
- use connective heat loss
behavioural adaptations to heat
- microclimate
- posture - bird oriented at 160degrees become white in terms of radiation - reflecting / deferring heat
- posture - also orient to wind
- activity - move the most when it is cool outside
- urohydrosis
what is urohydrosis?
defecating on the legs in some vultures to increase evaporative cooling on the legs
morphological adaptation to xeric conditions?
kidneys are highley efficient - dont actually need a ton of water
- salt glands in many orders - will stop from needing to dilute salt with water - makes sense for birds in saline environments
physiological adaptation to xeric conditions
some birds can be water free? - can survive for over a month without a direct water source - get all water from food sources
Behavioural adaptation to xeric conditions
some sandgrouse can carry water
- some birds have feather adaptations that create cups of water trapped within the feathers - can carry 18g of water for up to 35 kilometers
Can some gulls drink straight seawater?
gull with 10% of weight as seawater can excrete 90% of salt in 3 hours - comes out as 5% water remaining compared to 3% in birds without salt glands
How much water in birds is saved and reused?
of 6L of water, some birds can save 5.5L of that
How do birds deal with short term food shortage?
shrikes may store prey in caches - but animal prey decomposes quickly
How do birds deal with longterm food shortage?
some birds will cache seeds which can be stored for much longer as long as they remember where the cache was
three types of bird movement?
disperal - one way movement - breeding dispersal and natal dispersal (move from where hatched)
irruptive - unpredicatble / aseasonal
Migration - predictable / seasonal
Which bird has the longest migration?
the arctic tern
four types of migration
longitudinal migration
parallel migration
leap frog migration
cross-wise migration
What is partial migration?
some individuals of one species will migrate and some individuals will not
- resources are available in a portion of the range year round, while not through the rest of the range - so the individuals with less resources will have to migrate
- low quality individuals will be outcompeted so they will have to leave - it is never advantageous to leave if you do not have to
What can happen as the result of partial migration?
- will either speciate if both strategies prove to be viable or combine if one strategy is slightly more advantageous
What is leap frog migration
the individuals furthest north will leap frog over the residents of the same species and go the furthest south - can be a partial migration or a full migration
What is site fidelity?
returning to the same location every year - homing
- breeding location
- non breeding location
- natal location - going back to where they hatched
some individuals return to the same site within meters - will use the exact same nest multiple years in a row
why have we only recently started tracking songbird migraiton?
song birds were too small for traditional types of trackers as they were too heavy compared to bird weight
- MODUS radiotransmitters are very small so they can go on songbirds and now radio towers can track them when they pass
are breeding and wintering areas linked among a population?
both are correct, some areas are highly connected meaning the same set of inidividuals at a breeding area will winter at the same area
some are not connected at all meaning there is little similarity between a group that breeds in one area and a group that winters in another
What is the theory behind the evolution of migration?
may have started with altitudinal migration where there was not enough resources to live at high altitutdes year round
is migration strategy linked to diet?
yes generally specific groups migrate in similar ways
why do many north american birds not go all the way to south america?
lots of competition in the tropics and simply too far / not worth the effort
Why might there be differences in migration patterns between ages and sexes?
younger birds may be of lower quality and have to use lower quality sites
Three hypothesis on age and sex differences in migration
Arrival time hypothesis - males must return early to establish territories
Body size hypothesis - larger birds can winter farther north
Dominance hypothesis - dominant birds can exclude subordinates and force them to move further south
Trade off for leaving early for breeding grounds - advantages and disadvantages
too early arriving to breeding grounds - winter still may be in progress and food / resources may be limiting
benefit to be early because you can get the optimal nesting location or territory
- exaggerated in arctic areas
Trade offs for returning early to wintering areas - advantages and disadvantages
- returning early can mean lots of nutrients and less compitition with other migrants
- disadvantage – you have to time movements with what you assume to be the site conditions - may be out of energy because you stopped less during migration - have to hedge bets that nutrient pulse is still present in the site you want to go to
How does social behavior affect migration timing decisions?
unsure of social relationships among flocks - sometimes one goose leaving will prompt the entire flock to migrate
mostly communication within a species but not restricted to that point
- parents will prompt young to prep for migration flights
- theres likely alot more influence of social behaviour than we realize
Other factors for deciding when to migrate and when to return>
length of breeding season - consider arctic breeders - very short breeding season
- length of nesting cycle - geese have 25 day incubation and long development time
- altricial young are helpless young - once good to go very little support from parents
- precocial are active young
Adaptations on fat storage may affect migration timing
what will migration of migratory geese follow?
will often migrate north keeping pace with spring - will follow greenery - will often skip ahead in march april into canada to bet hedge on excess crop waste
general factors affecting migration route selection?
topography - mountains / bodies of water
winds - seasonal and frontal variation
food availability with seasonal change
historical affects
How many flyways do we have in north america
4
pacific, central, mississippi, atlantic
How do birds find their way?
magnetic compass
stellar compass
solar compass
wind
What are some local (proximate) cues for bird migration?
photoperiod regulates the physiological preparations of birds
- photoperiod triggers zugunruhe which is a sense of restlessness prior to migration
What is zugurnruhe?
sense of restlessness prior to migration
What is einschlaufpause
a break in the pause
- decision occurs at dusk
- decsison to start migration now or not
- happens at night / in the evening
Review some aspects of frontal movement in wind direction etc etc
What are some benefits to migrating at night?
for passerines - decrease predation risk and increase water retention (less heat), decrease metabolism devoted to cooling, allows to refuel in daylight when they can actually forage
- soaring birds may migrate midday due to taking advantage of upward thermals generated by convection
- raptors want to use thermals as well
why do birds migrate at different levels
flight mechanics and just how the birds are built
- flapping is energy demanding
- more winds up at higher altitudes
How does bird ecology change during migration
hyperphagy - eat as much and put on as muhc weight and fat as possible
- blackpoll warblers can go from 11-30 grams over a few days
- use fat rich food when possible
- sometimes absorb digestive tract - so food stays on as fat
- can shrink other organs to accomodate food storage
How do birds use the solar compass?
- because sun moves its difficult to tell location from it - must synch internal clock with sun movements to provide a relative reference - allows birds to compensate for motion of sun and stay on course
Describe the sun arc hypothesis>
Idea that birds sync movements with the sun with an internal clock - to use the sun to navigate
- requires a very precise internal clock
- sun is higher at noon in the south than to the north
- rises later in the west than east
- a bird will learn the path of the sun across the sky then if displaces as in homing experiments it can compare the path it knows the sun should take with the path the sun is observed to be taking and use this information to figure out which direction it needs to go home
- use in combination with magnetic compass
Define systematics
describes phylogenetic relationships of birds
Define taxonomy
- provides a set of names to describe relationships between birds
Define phylogenetics
- a subfield of systematics focuses specifically on reconstructing evolutionary relationships among organisms using genetic techniques
Define bioinformatics
A subdiscipline of biology and computer science concerned with the aquisition, storage, analysis and dissemination of biological data
Explain early sequencing studies
- early work started with small numbers of bases only
- often asked questions at the species or subspecies level
- ## needed to take into account variation within populations too
What was important about the avian tree of life project?
- looked at longer sequences
- larger dataset with 170 species from almost all famillies
- targeted informative parts of the genome
- could analyze higher relationships
Three approaches to systematics
eclectic / traditional approach
- numerical taxonomy
- cladistics
Explain the traditional approach to systematics
- described details of a particular trait
- covered a range of species
- showed patterns of change
- developed evolutionary scenario to arrange phylogeny
- done entirely on comparative anatomy, based largely on phylogeny, had to develop an evolutionary scenario to arrange the phylogeny which was subjective
Explain the phenetic/ numerical approach to systematics
- measures a wide number of features on a wide dataset
- run statistical packages to get a similarity index
- find clusters of species or other groups that seem to make sense
- still based largely on comparative anatomy
- had to find the same trait in a large enough set to calculate the similarity index
Explain the cladistics approach to systematics
= select set of species to examine for a small number of traits (ingroup)
- select some very different species for comparision purposes (outgroup)
- distinguish primitive traits (shared with others) from derived traits (unique to group of species)
- do this as hypothesis testing and cycle around
- accuracy dependant on which colors you look at - can run into difficulty with convergent evolution
What makes a good or bad trait for systematic / phylogenetic analysis?
- must be genetically controlled - not too environmentally plastic
- variable but not too variable - bill shape works on mainland but not on islands
- behavioural and ecological traits do work
- morphology and physiology will work
- decent results in the past with protein electrophoresis
- molecular biology is the main approach nowadays
What was protein electrophoresis?
one of the first approaches to modern genetics - measured gene prodcuts
- considered conservative
- not as variable in birds compared to other groups
- cumbersome
What is DNA hybridization?
start of molecular biology takeover in modern systematics / genetics
- heat DNA gently
- H bonds break and DNA becomes single stranded
- Cool to reform double helices
- Related DNA samples will reform double strands at higher temperatures
- more distantly related DNA samples would reform at lower temp
Debate between traditional and molecular phylogeny
traditional - classical results supported from DNA length variation
- molecular - sequencing approach shows different patterns
What is ultimately the best approach for molecular phylogeny?
simply to sequence the entire genome - birds have relatively small genomes
- provies a complete overview of sample and relationships
- does not leave much up to assumptions or chance
- dont have to worry about isolating specific sequences on the DNA
Do we need a phylogenetic species concept for molecular / whole genome data?
- molecular techniques allow us to compare birds QUANTITATIVLEY
- phylogenetic species concept works much better for molecular data than the biological species concept
Downsides of the biological species concept?
- defines a species as members of populations that actually or potentially interbreed in nature
- somewhat arbitrary
- not testable in the field and difficult to observe
- tends to lump
Lumpers vs splitters debate?
Lumpers - biological species concept
- tends to lump interbreeding groups
- lumped northern flickers, yellow rumps, and northern orioles
- dominant concept used to name species
Splitters - phylogenetic species concept
- tends to split groups charactized by unique combinations of derived traits
- interested in highlighting historical divergences and separations
- may lead to a doubling of named bird species
Assumptions made about foraging behaviour?
- individual is confined by its morphology on what foods it can access
- food is distributed evenly across the environment in certain patterns both spatially and temporally
- inidividual needs to find lots of food for maintenance and breeding
- individual may be prey and therefore distribution is analyzed by predators
Comparison of resources and predator vulnerability to determine flocks vs territories?
Flocks
- patchy resources favours flocks
- high predator exposure favours flock foraging
Territories
- uniform resources across time or space favours territory
- protected from exposure does not favour territory but decreases the value of flocks
What ultimitaley determines territoriality?
The benefits of defending territory have to outweigh the costs
- benefits are easy acquisition of resources
- costs are the time and energy needed to defend resources
- if benefits outweigh costs then territoriality is adaptive
- influenced by resource availability and need
Why do big birds need bigger territories?
need to consume more food / larger food
- more territory = more food available
Why do predators need large territories
Because flocking birds may not be a consistent resource in a small area, need to cover a much larger area to have reliable prey to hunt
What is the relationship between mean territory size and number of competing species? for a single species
- linear relationship
- as number of competing species increases the densities of individual species will decrease - ie the mean territory size will increase.
How is territory size affected by resource availability?
The density of available resources is related to territory size - inverse
- higher density of resources means you dont need to defend as large of a territory
- low resource density means territory size needs to be large to compensate
Type A territories?
also known as multiple use territories
- get food, water and nest sites all in same location
- non overlapping
Type B territories?
Core territory
- resources may be limiting
- benefits are less than costs of defending and foraging in territory
- may defend a core, nest or female but forage elsewhere
What determines territory shape?
natural barriers
topography
defensive behavior
How do birds migrate if it is cloudy?
also use magnetic compass
How does magnetic location work?
via a compass and a map
- direction finding magnetic field based on photopigments in eyes - able to see magnetic fields
- map system on magnetite iron ixide receptors in trigeminal nerve that are sensitive to small changes in the topography of earths magnetic field
Why migrate at night in the fall?
Strong headwinds in the fall, dont want to have wind antagoniszing against you - makes sense to migrate at night
How does the stellar compass work?
Birds have some capacity to orient to certain stellar bodies or constellations in order to both orient and navigate in the nighttime - probably use in coordination with magnetic fields
- can orient within 35deg of the north star
- species and location dependent
Which birds are more likely to migrate longitudinally (East to west)
diving ducks and swans
Other possible orintation / navigational clues?
Olfactory - seabirds can use smell to find their burrows
- pigeons have an olfactory map to find roosts
Sound - low frequency waves, crashing sea waves
Wind direction
vector navigation
learning
How do birds learn migratory routes?
- some birds like wooping cranes learn their migration routes by following their parents
- knowledge is lost when the species is reduced and there are no longer any wild birds using the flyway
- operation migration and wildlife service teaching migration to captive reared wooping cranes released into the wild
Bi coordinate navigation - how does it work and who uses it?
- using X and Y axis to navigate
- only a few species use it - know where home is and where they are in relation
- earths magnetic field can provide a map of horizontal space - intensity of magnetic field provides info
- and sun arc hypothesis
- basically birds that use multiple methods of locating, know where they are and where they need to be instead of just knowing where north is and what angle to go relative to north
Evolution of migration - is it a tropical bird breeding strategy or a temperate bird survival strategy in terms of reproduciton, mortality rates, site dominance, resource
Reproduction - highest in temperate (high resources but for a limited time) - migrants - lowest in tropics
Mortality rates - highest in temperate zone , lower in tropics
Site dominance - temperate residents get cavities, nest access is variable in the tropics
Resources - more variable in temperate zone but less competition - very species specific
Birds are oviparous, what is this?
Birds lay eggs that hatch externally
What is the purpose of reproduction?
replace adults
- provide genetic variation for natural selection
- males have small investment physiologically but can provide other care
- females have large investment in egg plus other care
How many ovaries do birds have?
only one - rest of the structure is the oviduct
How often do birds reproduce?
once, or multiple times in one short time - seasonally functional ovary
Define oocyte
cells that give rise to ova - predermined number
Define follicle
vascular tissue that connects and nurishes ova; forms yolk
Why is follicle growth variable?
time to become reproductively active
- months in small birds to years in large birds
- grows much quicker prior to ovulation
- a yolk will form in 4-16 days
- will begin to develop follicles way earlier prior to reproduction - takes energy - 4 months before reproductive event
Energy expenditure for females during reproduction
- blood glucose levels double
- mobilize calcium from bone (waterfowl)
- daily energy requirement 10-70% higher during egg production (laying)
- large species can store nutrients for weeks to help out - geese are 20% heavier on arrival
Seasonal change in male reproductive organs
- seasonal increase may be up to 300X for testicles
- may reach up to 10% body weight
cloacal protuberance - define
bulge over cloaca - IN MALES
- gives extra reach
- keeps sperm about 4 C cooler
