Iain Barr Flashcards
What is a parasite
Organisms that feed on other organisms
Dependent for food and development
Fitness effects are negative
What forms can a parasite take
Bacteria – Viruses – Worms – Flies – Fungi
5 common types of parasite
- Malaria
- Tapeworms
- Nematodes
- Wolbachia
- Brood parasites
Describe a simple life parasite life cycle
Reproducing adults in the definitive host alternate with free-living egg or larval stages
Describe a complex lifecycle
Include additional larval stages (which may reproduce asexually) in one or more intermediate hosts.
What hurdles do parasites face
– Attachment to the host
– Withstand defences
– Competitors and predators
What two forms of defenses do hosts have
Constitutive and inducible
What are constitutive defences
Ones which are always present ie
Common to healthy animals
General protection
Wide range of parasites and disease
What are inducible defences
responses activated through a previous encounter with a consumer or competitor that confer some degree of resistance to subsequent attacks.
How can parasites limit populations
Limit;
Demographics
Body size
Distribution
Life cycle of Leucochloridium paradoxum
Bird has the flatworm parasite Passes eggs in droppings Miracidia hatch Infect snail living close to water Moves into digestive system Develop Gather in the tentacles Create eye-catching patterns Bird eats the snail/tentacle Snail may seek the light
What is brood parasite
organisms that rely on others to raise their young.
Types of brood parasites
Cuckoo and cuckoo wasps
How are hosts adapted against brood parasitism
Removal of parasitic eggs by the host
Hiding of the nest
Identifying the parasite and killing/starving
Abandoning the nest and re-nesting
What counter adaptations do brood parasites have against hosts
Laying mimetic eggs
Specialising on one host
Destroying nests if the eggs is rejected
What are the 4 phenotypes of wolbachia
male killing (death of infected males). This selectively allows females to survive and more likely to reproduce even in the absence of males. feminization (infected males grow as either fully fertile females or infertile pseudo-females) parthenogenesis(reproduction of infected females asexually) Cytoplasmic incompatibility (the inability of Wolbachia-infected males to successfully reproduce with uninfected females). This method causes a certain Wolbachia strain to be more dominant over the others.
How is wolbachia passed down
Wolbachia are not found in mature sperms, but are found in mature eggs. So, the infection is carried along to offspring by infected females but not males.
