Week 11 Flashcards
Why is studying birds important?
Radiated into a diverse range of:
* Habitats
* Morphological forms
* Life history strategies
What are the practical reasons for studying birds?
Visual, audible and obvious!
* Well studied - lots of basic information
* Live at relatively high densities
– Easy logistics
– good sample sizes
* Short generation time (for vertebrates!)
Why are birds easier to study?
Easy to:
– Catch
– Mark
– Observe
Why are birds use to study reproductive behaviour?
– Find nests
– Encourage into nest boxes
– Observe nest behaviour
– Access and quantify reproductive success
How are birds easy to manipulate?
Easy to manipulate:
* Signal characteristics e.g. Song, plumage
* Mate choice
* Clutch/brood e.g. brood size
Can be repeated in captivity
Why is cross fostering useful?
Used to be able to differentiate between inherited and learned behaviours
How can birds be tracked?
Using satelite and geolocators
Why is remote tracking behaviours useful?
Understanding differences between or within population ie males and females do they migrate differently
What signals migration to occur
What are ibuttons and why are they useful?
Tiny sensors that can detect things like temperature and humidity
Can be used to monitor nest incubation or causes for nest failings
What are PIT tags?
Microchips that can be added to bird legs to track an monitor them
What is an experiment using PIT tags?
Used to identify wildbirds birds for cognitive studies
Faster learning in
* Younger birds
* Birds with ‘bold’ personalities
How can PIT be used to show social behaviour?
Feeding dens that only allow females in - males wait around the outside as a form of mate guard
Feeding dens that only allow males in - females dont wait
Why are molecular markers useful?
Identify:
Sex
Individuals
Presence of pathogens
What questions can be asked about the origin of extra-pair paternity?
- Which factors influence when extra-pair paternity occurs?
- Why do females seek extra-pair paternity?
What is an overview of Bullock’s orioles?
Icterus bullockii
Socially monogamous
Nest as solitary pairs or in colonies of pairs (1-13 nests per tree observed)
Colonies do not form due to food or habitat distribution
What is the overview of Yellow-billed Magpies nesting?
Smaller than other corvids
Sedentary
Nest early (February)
What is the overview of the nesting of bullock’s orioles?
Migratory
Arrive and nest, April–May
Can defend nest against YB Magpies but not other, bigger, corvids
Are orioles choosing to nest near Yellow-billed magpies?
Orioles were more associated with magpies than expect by chance
Orioles choosing to nest near to magpies causes semi-coloniality
What is the benefit for orioles of nesting near to magpies?
Less predation on oriole nests located near magpies
No effect of proximity to other orioles
Orioles prefer to nest near to YB magpies to avoid nest predation!
Causes orioles to be semi colonial (i.e. often nesting at higher density)
How did they test for whether Orioles were nesting near YB magpies?
Assessed levels of nest predation
1. With or without magpie within 50m
2. With just another oriole within 50m
How does density effect extra-pair paternity?
EPP decreases with greater nearest oriole neighbour distance (lower density)
High density – 48% of chicks are EP
Low density – 16% of chicks are EP
Density effects levels of infidelity
Why does density effect extra-pair paternity?
Allows females more extra-pair mate choice
What is the relationship between males and extra-pair paternity?
Male with no near neighbour very low chance of EPP
Older males low cance of EPP
Yound males upto 100% of eggs EPP
What are the benefits of mate choice?
Direct benefits
- Paternal care
- Territory quality
Indirect ‘genetic’ benefits
- Increase vigour of offspring
- Increase attractiveness of offspring
What questions can be asked about female mate choice?
Do genetic benefits to mate choice exist?
Which genes underpin such benefits?
What is the Major Histocompatibility complex?
Suite of replicated genes central to the vertebrate acquired immune response
Extraordinary levels of genetic variation
Individual differences influence pathogen resistance
More MHC diverse individuals can defend themselves against more pathogens
Where was immune system based smells been tested and linked to mate choice?
In mice and humans:
* Female mate choice influenced by MHC
What is the hotshot model in respect for MHC?
Individual survival & condition is (partially) determined by the MHC genes they carry
– Diversity of different alleles
– Specific alleles
Mate choice based on condition dependent cues
– Good genes passed onto offspring
– Male MHC diversity (or type) important
What is the romantic model in respect for MHC?
Female prefer mates which have compatible MHC genes to their own
– prefer males with most different set of MHC alleles to their own to maximise offspring MHC diversity
Choice based on direct cues, e.g. smell
– MHC dissimilarity important
What is an overview of the Seycehlles Warbler system?
Long term study
Small contained and isolated population
All individuals marked
Monitor all breeding attempts
Determine social pair bonds
All parents and offspring blood sampled
What is the parentage seen in the Seychelles Warbler?
Parentage:
* 40% extra-pair paternity (infidelity)
* Assigned all extra-pair males
How did they track for the importance of the MHC in the Seychelles Warbler?
MHC genotyping
* Screen individual MHC variation
* Two measures of MHC (across 4 replicated loci)
1. MHC similarity between individuals
2. MHC diversity of each individual
What was the outcome for MHC-based social mate choice in the Seychelles Warbler?
No evidence for MHC based social mate choice
What can impact the lack of mate choice in the Seychelles Warbler?
Social mate choice restricted – habitat saturated
How does MHC variation impact EPP in the Seychelles Warbler?
MHC similarity
* EPP - constant across different levels of MHC similarity between female and pair male
MHC diversity
* EPP Higher when the social male’s MHC diversity is low!
And they end up fertilised by higher MHC males
What is the fitness consequences of MHC-based EPP in the Seychelles Warbler?
Positive association between MHC diversity and juvenile survival
Mean life span of individuals with:
less than 4 alleles = 1 year
more than 4 alleles = 2.5 years
