Ecological networks Flashcards
What is the definition of coevolution?
Change in the genetic compostion of one species in response to a genetic chnage in another = RECIPROCAL INTERACTION
(traits must be heritable)
What are non-specific examples of antagonistic relationships?
herbivore-plant, pathogen- host, parasitoid-host, predator-prey
What are the 3 requirement fro evolutionary change?
1- trait confers fitness advantage
2- genetic variation for trait
3- trait is heritable
What are the 2 types of specialisation?
Genetic and species
Example of mutualistic coevolution
Lycaenid caterpillars providing ants with honeydew in return for protection
Example of predation coevolution
Crossbills and cones: cross bills prefer smaller cones so cone size increased. Then beak size increased = divergence of crossbill populations
2 occurrences that may look like coevolution but are NOT
1- traits evolved in 1 species before association began
2- 1 species tracks another’s evolutionary changes (not reciprocal)
Give an Example of phenotypic level antagonism?
Running speed
What are the 2 types of genetic level antagonisms?
Escalation and Red Queen hypotheses
Difference between symmetric and asymmetric interactions?
Symmetric- same fitness effect e.g. obligate lethal parasite- consequence = death
Asymmetric- arms race
e.g. prey running for LIFE but predator only running for dinner
Example of escalation at genetic level
Taricha granulosa newts produce TXX toxin + Thamnophos sirtalis snakes evolved resistance
Example of red queen hypothesis at genetic level
Trematodes can only infect snails with specific genotype so rare snail genotypes less susceptible = reproduce more = more common = more susceptible
What is macroevolution?
evolution of whole taxonomic groups over long periods of time.
What are 4 ways to test for coevolution?
1- Time-shift assays
2- map phylogenies of interacting species to look for concordance
3- determine if one of species if dependant on other for fitness
4- correlate trait values across populations
What 3 factors structure ecological networks?
indirect effects, keystone species, anthropogenic disturbance
What are nodes and edges?
nodes (species), edges (feeding links)
What is connectance?
fraction of possible links in web that actually occur
What does robustness increase with ?
connectance
How can food webs be studied?
observation, modelling, experiment
What are 2 conclusions made from food web models?
food chains should be short and complexity may reduce stability
What is apparent competition?
same trophic level- more competition for space
What is a keystone species?
Species whose impact on community/ecosystem is larger than might be expected by abundance (often predators)
What is the definition of an ecological community?
group of species that occur together in space/time and compete for same limiting resources
What is hyperdiveristy?
e.g. coral reefs, tropical rainforests
