Lecture 16: Behavioural Ecology and Biological Invasion

Question 1

Describe the the bandicoot, dingoes, domestic dog and cat situation

Answer 1

• Dingoes and bandicoots have a historical coexistence for about 4000 years
• bandicoots on mainland avoid domestic dogs but not domestic cats
• island bandicoots do not avoid cats or dogs – they were introduced only 200 years ago to Tasmania
• *prey naivete may be eroded through long term exposure

Question 2

What was the introduction of the opossum shrimp to flathead an example of behaviourally?

Answer 2

• behaviour mismatch

Question 3

Behavioural differences of the brown spruce longhorn beetle in it’s european native range vs NA?

Answer 3

• In europe they attack old stands of Norway spruce, primarily trees weekend by stress or recently cut
• In Nova Scotia they attack and kill healthy red spruce, white spruce and black spruce

**relationship seems to be more pathological with new host vs co-evolved host in native range

Question 4

Behavioural aspects of Africanized honey bees?

Answer 4

• descendants of S. African bees imported to S. America
• breed them with honey bee
• bees escaped and interbreed with european bees = aggressive hybrids
• will sting many times
• In africa there are many hive and nest predators so aggression is an evolved response to a community level response for nest protection. There is no other reason to exhibit that level of energy to aggression.

Question 5

What is a reason why some invasive species appear more aggressive than the species they displace?

Answer 5

• come from environments which heightened aggression is adaptive
  ex: Aggression in Africanized honey bee is thought to be a response to a higher diversity of nest predators in Africa

Question 6

Explain the response of Bell’s vireo to nest parasitism by cowbirds introduce din california

Answer 6

• bell’s vireos accept cowbirds, which are snuck in by females. They may even remove native eggs. Most birds will simply incubate the eggs, raise them without knowing anything. A female cowbird can lay up to 30 eggs per month
• results in low hatching and breeding success of vireos
  L> invest parental care, cowbird may hatch sooner and take a lot of host birds energy
• In the US midwest, natural range of cowbirds, vireos abandon parasitized nests

Question 7

Explain the effect of sea slug behaviour on dispersal of an invasive alga

Answer 7

• sea slugs are herbivorous gastorpods
• introduced to eat algal
• when it chews it up, it fragments it and the algal spread through these fragments
• sea slug increases the algal dispersal
• behaivour of the slug to chew it up a certain way to promote it’s food source

Question 8

List the roles of behaviour in colonization and establishment

Answer 8

1. Gregariousness
2. Cryptic Behaviour
3. Behavioural flexibility

Question 9

Roles of behaviour in colonization and establishment:

1. Gregariousness

Answer 9

• living in groups
• Cost: increased infraspecific competition, increased conspicuousness to predators and prey
• benefits: mate location, food location, predator swamping, easier to defend territory and resources

Question 10

Roles of behaviour in colonization and establishment:

2. Cryptic Behaviour

Answer 10

• facilitates human commensalism via hiding amongst elements of transportation network
  e. g. gobies, brown tree snake, cockroaches, ship rats

Question 11

Roles of behaviour in colonization and establishment:

3. Behavioural flexibility

Answer 11

• ex feeding innovations

ex: birds were more successful if they had more feeding innovations

Question 12

Brain size vs invasion success ?

Answer 12

• in birds it’s positive suggesting cognitive ability involved in success
• also seen in mammals
• does not in fish though

Question 13

Competitive displacement of native species is done via?

Answer 13

• via interspecific aggression which is often a mech for:
  1. Defence against predators
  2. Competition for food and space

Question 14

Explain the aggressive interaction between an introduced and native crayfish species in Europe

Answer 14

• they are generalist predators
• but they compete for habitat
• they need crevices for protection and to molt
• in between molts they are vulnerable
• if there is a high density of crayfish, these habitats become limited
• introduced crayfish seem to displace native species in part bc of plague but even when that is not at play it usually takes over. Size of crayfish usually decides who gets the shelter therefore non native crayfish also grow faster

Question 15

Apparent competition?

Answer 15

• two sp that would normally be resource competitors but have a common enemy, they will be in apparent comp to hide from that enemy
• ex: exotic crayfish (rusty) and a native crayfish. Exotic outcompetes them knocking them out of shelters, exposing them to bass

Question 16

Does behaviour vary across environmental gradients?

Answer 16

• it can
• Eastern mosquito fish and mediterranean tooth carp experiment : mosquito fish is very aggressive ands ill attack the carp BUT this behaviour varies…it is more aggressive inFW vs marine

ex2: ion poor water vs ion rich
L> one amphipod is dom in ion poor water while the other is dom in ion rich water
*intensity and direction of predation is revered along conductivity gradient; intraguild predation

Question 17

Intraguild predation?

Answer 17

• when an individual eats a member of the same trophic level..common in crustaceans

Question 18

Compare behaviour of S. American fire ants in their native and introduced range

Answer 18

• in the native range there is a single queen colonies, intrapseicifc aggression and territoriality are present. Ants form rival nests kill each other
• In the introduced range there are multi queen colonies with reduced intraspeicifc aggression, ants recognize each other and cooperate = super colony

Question 19

Explain the behaviour of argentine ants?

Answer 19

introduced to europe in the early 20th century

• formed the largest super colony ever recorded
• contradicts kins election theory = altruistic behaviour occur sonly between closely related individuals BC if you take individuals from Italy and place them in Portugal, the ants won’t kill each other, which violates this theory bc you’d assume only closely living to each other groups would show this altruism

Question 20

Explain the resource consumption hypothesis

Answer 20

• high impact invaders exploit resources more fully and rapidly than low impact invaders or natives, they have higher and more efficient resource consumption rates
• the most ecologically disruptive invaders in a system use key resources differently from native specie s
• especially by more rapid and efficient exploitation of such resources *e.g. higher predation rate, lower prey handling etc)

Question 21

Explain functional response

Answer 21

• the relationship between prey consumption and prey availability (density)
• attack rate initially and then maximum feeding rate at the plateau

Question 22

What’s going on with the round goby’s functional response and calcium concentration

Answer 22

• varies with calcium concentration
• higher maximum feeding capacity at high calcium
• makes sense since they are adapted to ion rich water
• in low calcium water, their max feeding rate is much lower
• Ex of environmental matching

Question 23

Explain the environmental matching hypothesis

Answer 23

• the impact of an invader is inversely correlated with distance from its environmental optimum
• *species have a physiological sweet spot
• as you move from that sweet spot, the species does not do as well

Question 24

Explain the context dependency of an invader’s impact

Answer 24

influence of the physical environment, interactions with the resident community and ecological impact are all tied together

**so impact can vary over space and time under local biological and environmental conditions