Post on 24-Dec-2015
Habitat Preference - Choosing a Place to Live
MIGRATION
HABITAT PREFERENCES
1. DISPERSAL
2. MIGRATION
DispersalMigrationTerritory
Passive dispersal
Dispersal
DispersalMigrationTerritory
Definition - generally one-way and permanent movement of animals fromone place to another
Natal Philopatry vs Natal Dispersal
Dispersal
DispersalMigrationTerritory
Natal Philopatry
Costs- inbreeding depression
- increased competition
Benefits - inbreeding
- local familiarity
Natal Dispersal
Costs- energy used in dispersal
- increased predation
Benefits - reduced inbreeding
- avoid competition
- lack of local familiarity
Dispersal
DispersalMigrationTerritory
Lions - sex dependent dispersal patterns
Remain in pride
Form new pride
Transfer to another pride
Nomads
Left area
Died
Disappeared
% of lions0 100
Females
Males
Dispersal
DispersalMigrationTerritory
Inbreeding Depression
- field mice
Margulis & Altman. 1997. Anim. Beh.54: 397
% not breeding
Days since mating
Outbreeding mothers
Inbreeding mothers
Dispersal
DispersalMigrationTerritory
Inbreeding Depression
Seychelles warbler - Acrocephalus sechellensis
Dispersal distance
% r
elat
ed b
reed
ers
in
adja
cent
terr
itor
ies
Closely related r >.35) Moderately related - .1 < r <.35).7
.6
.5
.4
.3
.2
.1
0.0
Eikenaar et al. 2008 J. Evol. Biol. 21: 1106
Dispersal
DispersalMigrationTerritory
Outbreeding Depression
- song sparrow
Searcy et al, 2002
Distance apart
Dis
crim
inat
ion
Females
Males *
* * *
*
*
* = signficantly different from random
Dispersal DispersalMigrationTerritory
Searcy et al, 2002 * = signficantly different from random
Schistocerca gregaria - migratory locust
Dispersal DispersalMigrationTerritory
Searcy et al, 2002 * = signficantly different from random
Schistocerca gregaria - migratory locust
Dispersal
DispersalMigrationTerritory
SolitaryDispersing
Migration
DispersalMigrationTerritory
Recognized for long time
Migration
DispersalMigrationTerritory
Functional Classification
1. Exploratory
2. Removal
Dispersal
3. Return migration
4. One-way migration
Migration
DispersalMigrationTerritory
3. Return migration
Long range
Migration
DispersalMigrationTerritory
3. Return migration
Short range
Three wattled bellbirdProcnias tricarunculata
Migration DispersalMigrationTerritory
Components
1. Periodic timing -daily-tidal-lunar-annual - 1 - many years
Migration DispersalMigrationTerritory
Components
2. Track pattern
Loop One direction Multispecies
Migration DispersalMigrationTerritory
Components
3. Plane of movement
1. Horizontal2. Vertical
Plankton
Elk
Migration DispersalMigrationTerritory
Components
4. Geographical direction
-most are north - south
Albatross - east -west
Migration DispersalMigrationTerritory
Components
5. Direction ratio
Variation about mean direction
Migration DispersalMigrationTerritoryProcesses governing migration
W. Rowan (1925)
Junco
Treatment Response
Control Natural winter
daylength
No gonad growth
No migration
Experimental Increased
Photoperiod
(simulate spring)
Gonad growth
Northward migration
(even in winter)
Migration DispersalMigrationTerritoryProcesses governing migration
Change in photoperiod
Increased hormone secretion
Gonad maturation Migration
Preparation
Initiation
Migration DispersalMigrationTerritoryPreparation
1) Increase fat deposition
-rapid eating
-increase in stomach volume
-increase in fat load
100
80
60
40
20
0
Fat load(% of leanbody wt)
Non-migrants Short distance Mid-distance Long distance
Migration DispersalMigrationTerritoryPreparation
1) Increase fat deposition
Level of reserve can affect direction
e.g. red eyed vireo
Fat birds
Lean birds
Migration DispersalMigrationTerritoryPreparation
2) Zugenruhe - “migratory restlessness
Before onset
After onset
Migration DispersalMigrationTerritoryInitiation
Must determine a direction
1) Piloting - recognition of familiar landmarks
Migration DispersalMigrationTerritoryInitiation
Must determine a direction
2) Orienting - recognize and maintain compass direction
Migration DispersalMigrationTerritoryInitiation
Must determine a direction
3) True Navigation - identification of “home” from any direction
Need a) map sense - determine location relative to goal
b) compass sense - maintain direction relative to position
Migration DispersalMigrationTerritoryInitiation
How do you tell an orienting from a navigating animal??
displacement Orienting(or vector navigation)
Navigating
Zonotrichia leucophrys
Throup et al, 2007. PNAS 104: 18115
Breeding grounds
Wintering grounds
Zonotrichia leucophrys
Thorup et al, 2007. PNAS 104: 18115
Breeding grounds
Wintering grounds
Boles & Lohmann, 2003. Nature 421: 60
True Navigation in Lobsters
Pagurus
Migration DispersalMigrationTerritoryInitiation
Without external cues
Cataglyphis
Food item
Nest
591 m
140 m
Migratory Cues - Sun Compass
Starling
Mirror
Sun Compass
Kramer
Clear Skies Overcast
Is there an internal clock?
Direction at 0900 under natural sky
45º
Direction at 1500 under natural sky
45º
Direction at 1500 under natural sky after biological clock is delayed by 6h
45º
Changing position of the sun in the sky - azimuth
Star Compass
Polarized light
Polarized light
Polarized light
Clear sky Cloudy sky
Magnetic field
Magnetic field
Magnetic field
Magnetic field
Migrating in groups
Naïve birds singly
Group experiment
Experienced birds singly
Migrating in groups
Energetic costs
Pelicans
Gliding Alone (50 m) Alone (1m) In formation
Wingbeats /min
•
• •100
50
10
Heart beats /min
Weimerskirch et al, 2001
Migrating in groups
Energetic costs
Pelicans
Gliding Alone (50 m) Alone (1m) In formation
Wingbeats /min
•
• • ••••• •
100
50
10
1 2 3 4 5 6
1
23 4 5 6
Heart beats /min
Weimerskirch et al, 2001
Evolution of Migration
1. Higher incidence in ephermeral or unstable habitats
2. Reproduction - allows exploitation of seasonally rich food supply
3. Predation and reproductive synchrony
Migration as a conditional strategy
Turdus merulaEuropean blackbird
Migration as a conditional strategy
Turdus merula
Resident in preceding winter Migrant in preceding winter
resident
migrant
resident
migrant
Male Female Male Female