1 - Spatial Distribution Flashcards
(27 cards)
What is dispersal
Movement away from the place of birth
Do all species disperse
Yes – every species exhibits some form of dispersal
What is active dispersal
Movement under the organism’s own power (e.g. animals)
How is active dispersal studied
Marking, GPS tracking, proximity detectors
What is passive dispersal
Movement by external forces like wind, water, or animals
How is passive dispersal studied
Genetic markers and genotyping
Why do organisms disperse (4)
Avoid competition
Avoid inbreeding
Avoid local extinction
Maximise reproductive success
What determines species spread
The dispersal kernel – how far individuals move
What is Reid’s Paradox?
Trees recolonised Europe faster than predicted – explained by rare long-distance dispersers
What affects species distribution more: mean or variance of dispersal distance
Variance is more important
What is migration
Regular, round-trip movement between locations
How is migration different from dispersal
Migration is cyclical; dispersal is one-time
What is diurnal migration
Daily movement (e.g. zooplankton avoid predators during the day)
What is seasonal migration
Movement to exploit resources (e.g. wildebeest, migratory birds)
What drives migration evolutionarily
Resource availability
Predator avoidance
Climate conditions
How do organisms time migration
By tracking:
Photoperiod
Temperature
Food availability
What navigation methods do migrators use
Landmarks
Celestial cues
Sun compass
Earth’s magnetic fields
Do species vary in group size
Yes – some are solitary, others live in groups or mixed-species communities
How does group living reduce predation (4)
Dilution effect: lowers individual risk
Confusion effect: harder to target one
Increased vigilance
Group defence
How does group living help with feeding (3)
Increased hunting success
Capture of larger prey
Info sharing and food learning
What are the downsides of group living (3)
Attracts predators
More disease and parasites
Resource competition
What is monogamy
One male and one female pair up – common in solitary species
What is unimale polygyny
One male mates with multiple females – common in small groups
What is multimale polygyny
Several males and females breed in large groups
