Brood Parasitism & Arms Race

Question 1

How do Mexican free-tailed bats identify young?

Answer 1

Visual, vocal and olfactory cues

Question 2

How many young are found in Mexican free-tailed bats’ creches

Answer 2

> 4000 pups per meter squared

Question 3

What is brood parasitism

Answer 3

When organisms rely on others to raise their young (i.e: birds laying eggs in others nests)

Question 4

What is intraspecific brood parasitism

Answer 4

when eggs are laid in conspecific nests

Question 5

What is interspecific brood parasitism

Answer 5

When eggs are laid in other species nests

Question 6

Name a species that shows brood parasitism

Answer 6

Cuckoos
Cowbirds
Great tits

Question 7

What are 3 costs to brood parasitism

Answer 7

Potential rejection of offspring?
Imprinting – potentially offspring won’t be able to reproduce if not imprinted onto own species
Future genetic lineage of host is at risk – own offspring may not survive
If host population declines, so does the parasite as they have no host nests to raise their young – have evolved out of parental care
Parasites sometimes kick host eggs out of nest
Host hatchlings can be killed by parasite
Parent host can abandon own offspring if invaded

Question 8

What are 3 benefits to brood parasitism

Answer 8

More energy and time for the parent to reproduce again
Parent doesn’t have to give up resources
Increased fecundity
Protection of offspring – parental care provided
If you are an obligated parasite, you have no risk of becoming a host
Less incubation time for parasite

Question 9

What types of species are likely targeted as hosts?

Answer 9

Species smaller than the parasite

Question 10

What is the mafia hypothesis

Answer 10

parasite may be monitoring the host nest and will damage nest if parasite egg removed

Question 11

What are 3 reasons hosts tolerate parasite eggs?

Answer 11

Hosts don’t simply reject parasitic eggs:

• Due to mimicry of eggs – cuckoos can lay eggs same colour as hosts
• Risk of host kicking out own egg
• Host is too small/ unable to break parasite eggs – choice is to either abandon nest or remain
• Host may
• Mafia Hypothesis

Question 12

What is the arms race between hosts and parasites

Answer 12

They are coevolving

• As hosts develop adaptations against parasites, parasites evolve new mechanisms to parasite

Question 13

Which species uses egg mimicry

Answer 13

European cuckoo

Question 14

Which species best rejects cuckoo eggs

Answer 14

Black birds

Question 15

What happens if a cuckoo lays in a wren nest before the wren lays?

Answer 15

Wren abandons nest

Question 16

What happens if the cuckoo evicts wren young out of nest

Answer 16

40% of the time, wren abandons nest, cuckoo chicks then starve

Question 17

How do cuckoo chicks fool the host wren

Answer 17

they mimic begging calls of wren young

Question 18

What mechanism makes wrens gather more food for cuckoo chicks

Answer 18

Cuckoos mimic the sound of multiple chicks - encourages parent host to gather food for multiple chicks rather than just one

Question 19

What are 3 ways cuckoo chicks fool parent host

Answer 19

Egg mimicry
Begging/ alarm call mimicry
Light reflection