Introduction to E and B Ecology Flashcards
Define ethology and behavioural ecology
Ethology - Scientific and direct observation of animal behaviour
Behavioural Ecology - Function of behaviours and relation to habitats and ecosystems
What are Tinbergen’s four questions?
Function - What is the behaviour for?
Evolution - Where has the behaviour come from?
Causation - How is the behaviour achieved
Development - How does the behaviour develop?
What are environmental pressures?
Biotic and abiotic
Natural and anthropogenic
What is the allee affect?
It is the relationship between population size and individual fitness
Many species suffer a decrease in population growth rate when population density is low
Presence of high densities of individuals of the same species can increase the fitness of any one individual
This is down to a range of behavioural mechanisms that are inherently linked to survival and reproduction
What are the three main behavioural mechanisms in the Allee effect?
Predation
Social Systems
Mate Choice
Give examples of Predation behaviours that impact the Allee effect
- Cooperative anti-predator behaviour e.g. mongoose predator detection depleted in small groups
- Predator dilution e.g. caribou reduction in dilution and confusion effects as population decreases
- Anthropogenic effect e.g, trophy hunting rare species considered more valuable
Give examples of Social systems behaviours that impact the Allee effect
- Mate location e.g. lizards males in polygynous mating systems may have to range more widely in low density populations
- Breeding success e.g. African wild dogs small breeding groups less successful in producing and rearing young
- Hunting success e.g. wolves may rely on large groups to be successful
Give examples of Mate choice behaviours that impact the Allee effect
- Mate location e.g. butterflies difficulty in locating suitable mate at low population results in reduced reproduction
- Broadcast spawning e.g. sea urchins problematic in passive reproducers or those with low mobility
- Mate availability e.g. barn swallows non-preferred mate choice also results in reduced reproductive frequency
What properties does Ne assume?
- Population split into sub-populations where there is no migration between sub-populations
- Generations do not overlap
- Number of breeding individuals is the same for all generations and sub-generations
- Mating is random
- There is no selection
- Mutation is assumed to be unimportant
On what can behaviour affect Ne?
N - number of individuals in a population
r - populations rate of increase
Reproductive skew - how reproduction is partitioned in animal groups
What is reproductive suppression?
When mature, potentially reproductive individuals don’t breed
Influences Ne by reducing the proportion that do breed and therefore decreases r
If only one sex is suppressed then can increase reproductive skew
May be facultative or obligate
Dominant breeders can suppress subdominants via chemical or physical means
Give an example of reproductive suppression
Seychelles Warbler (Acrocephalus sechellensis)
- Population size limited by habitat
- Managers increased habitat with little effect
- Facultative cooperative breeders
- 1998-1990: 58 suppressed adults translocated to 2 new islands
- Populations showed explosive increase in size
What is sexually selected infanticide?
New dominant male to social group kills offspring sired by a previous male
Considered an adaptive reproductive strategy
Reduces juvenile survival and thus N
Reduces recruitment and thus population growth rate (r)
Infanticide has important implications for management
Give an example of sexually selected infanticide
Swedish Brown Bears (Ursus arctos)
- Killing one adult male can lead to deaths of non-hunted juveniles
- Cub survival continues to be low up to 1.5 years after
- Removal of one adult male is equivalent to harvesting 0.5-1 adult female
Why might migration result in extinction vulnerability?
Likely to experience changes in N due to;
- Vulnerability to factors that may change migratory patterns
- Experience habitat loss due to side ranging habitats
- Risk of suffering increased mortality on the move
Relying on chemical cues to orientate
- Can be destroyed or blocked by humans
Habitat loss of critical areas
Vital resources destroyed that migration requires
Patterns of migration result in high mortality
- Narrow corridors enabling poaching and hunting
