midterm 3 reup Flashcards
4 important extraembryonic membranes
1 - amnion - surround embryo and watery amniotic fluid
2- chorioallantois - blood supply, respiration
3 - allantoic sac - holds wastes
4 - vitelline membrane - surrounds yolk
What is the chalaza?
thin structure that keeps embryo centered and balanced in the egg
What is the purpose of the air cell in eggs?
Gas exchange occurs through the shell, will increase as gas requirements increase
3 important egg components?
Yolk - contains lipids proteins and water surrounded by vitelline membrane
Albumen - egg white - 90% water 10% protein - cushion / insulation
Shell - structural support / defense / gas exchange
Why might cliff nesting bird eggs be oblong?
To prevent rolling off
What does egg size / shape / pattern tell about bird ecology
often birds in the same family have similar eggs
- size is relative to size of bird
- camoflauge relates to environment
- eggs with no camo may be in better nests / better protected - cavity nesters
What is interesting about the Common Murres eggs?
will have different camo depending on habitat
How do birds keep their eggs cool?
will shade them or use damp breast feathers
- turn eggs to prevent adhesion and redistribute heat
What is the relationship between incubation period and egg weight in birds?
more incubation time means more weight - linear
What is piping ?
active hatching using egg tooth to break outer shell
What is the hatching muscle?
strong muscles on back of bird necks for upwards reflex to break shell w egg tooth
Why might hatching be synchronized in some precocial species
babies will run when born
- reduce time that chicks are waiting for parents / siblings to hatch
Is altricial and precocial a gradient?
yes
What is nidifugous and nidicolous?
nidifugous - young leave nest
nidicolous - young stay in nest
What is imprinting?
within hours after hatching will follow largest object
Costs and benefits of altricial v precocial
Altricial
Costs - high parental care, high energy requirement, high predation risk and potential loss of whole brood
Benefits - high growth rate, multiple broods and less investment / individual
Precocial
Costs - slow growth rate, harder to raise more than one brood
Benefits - less predation risk, less risk of losiong whole brood, low parental care, low energy
What is the optimal breeding time?
variable, food and temperature limited
- often early is better for more development before migration but owls will start in winter to be old enough to hunt young birds in spring
What is the role of hormones and photoperiod in breeding?
environmental light via neural receptors and the endogenous clock via pineal gland
- optimal time for reproduction
- synchronize pairs
- terminate reproduction
Ultimate and proximate cues for breeding season?
ultimate - determined by nat sec
- food
- nest sites
- climate
- predation risk
proximate
- temperature
- habitat
- social interaction
What is the role of hormones in reproduction>
to stimulate reproductiuon and induce ovulation
What is prolactin?
hormone secreted by pituitary - signals switch from breeding to brooding behaviour
- rise during egg laying and incubation
When do birds terminate breeding?
when no longer feasable to produce more young energetically
How does breeding relate to moulting
molting stage is nonbreeding - will go breed if food is good and mate is present, will leave when food is bad, mate is gone or young have grown
What birds may breed / molt in a non annual cycle?
tropical birds and seabirds
When does colonial nesting occur?
many seabirds, when food and nest sites are not uniformly distributed
Benefits of colonial nesting?
predator avoidance
synchronized breeding will overwhelm predators - fraser darling effect
Costs of colonial nesting?
Fighting
disease
parasite load
confidence in paternity and maternity
attract predators
lost young
infanticide
limited by food supply and literal space for nests
What is the optimal colony size?
somewhere in the middle bell curve, more individuals for group protection benefits but less parasite / disease
Difference between song and call?
song - males during breeding
call - both sexes yearround
Difference between information calls and alarm calls?
Information calls - short and broad freq
Alarm - faint long and narrow freq - hard to locate caller
What season are most songs produced
late spring cuz breeding
Why do birds sing
- different songs for different parts of territory
- mate acquisition
- individual recognition
-dialect matches habitat
What is repertoire correlated with?
condition of male
How do birds learn what to sing?
some are soley genetic some are learned
- usually have a critical learning period - usually in first 50 days but not always
- go through a silent period
-then subsong period where they practice what they remember
- then song crystalization where the genetic auditory template is modified and they will be able to sing the song even if deafened later in life
What is vocal mimicry?
used to intimidate other birds or impress females
Why have courtship displays? 4
pair bonding
synchronize sexual readiness
stimulate hormonal cycles
species recognition
Define displays?
specialized acts that transmit information between sender and reciever
What is the bet hedging strategy for egg laying?
if the optimal clutch size varies from year to year then you should always go for a larger than average clutch in a good year you can raise them all, if its a bad year you can sacrifice some eggs
Why do nest parasites have an advantage?
usually have a lower incubation time to hatch early and give competitive advantage in the nest - sometimes will try to throw out other eggs - recieive more food
Three models for mating systems
Social systems - old approach, includes pair and group bonding
Mating systems - include actual genetic investment in offspring plus social interactions
Cooperative breeding systems - usually seperate topic but a social option with both breeding and nonbreeding group members
5 mating organizationa
Monogamy - 1m 1f
Polygamy - multiple mates of one sex, could be either sex
Polygyny - 1m multiple f
Polyandry - multiple m 1f
Promiscuity - little organization , males win
5 terms for alternative mating strategies
EPC - extra pair copulation - mating outside a social pair bond
EPF - extra pair fertilization - outside of pair bond
Mate guarding - male watches female closely
Mating tactics - strategies used by birds
EPY - extra pair young - result of all the messing around
What is the environmental potential for polygamy?
recognizes need for resouce abundance to make up for less parental care
What is the result of high polygamy in terms of sexual selection?
crazy sexual selection
Types of polygyny depending on external factors
rich territories = resource defence polygamy
easy food / nests that are hard to defend = male dominancy ppolygny- leks
females in groups = female defence polygyny - harems
Mutualisms with fruit - male dominance polyygyny seen in tropics often leks
Why might helpers exist in some social systems?
many species have excess populations with nowhere to go - will choose to help couple to pay rent
Costs and benefits of helping in mating
benefits
- helper stays alive hopefully to become dominant
- gets inclusive fitness
- learns
- increase overall young raised
costs
- no breeding success
- no guarantees of getting old parental site
- may die before breeding
- no effect on individual fitness (no reproduction)
Illustrate the relationship between brood size and survival of young for an optimal clutch size of 6 eggs?
If the optimal size is 6 eggs, then anything above that number would decrease the survival of individual young as there are too many mouths to feed, survival decreases as brood size increases above the optimal
- probably less effect on having fewer than six eggs, but would decrease number of offspring survived as there are fewer offspring
Describe the spectrum of courtship displays and mate attraction in birds
Depends on how you define spectrum
- less elaborate - calls and songs
- more elaborate - bright color changes - can increase predation risk
- very elaborate - courtship dances - can be risky for predator attraction - time and energy consuming
- super elaborate - sexually selected structures ie peacock tails that pose great risk to own bird survivability
Compare hatching synchrony and asynchrony, when is one preferred over the other?
Depends on species specific ecology
- generally synchrony is preferred in precocial species to prevent chaos
- asynchrony is preferred in altricial species for more managable feeding
When does egg development begin?
Only at the start of incubation
Which hormones are involved in reproduction?
FSH - stimulates gamete growth - sperm and eggs
LH - induces ovulation
