Social Insects Flashcards
explain social insects
- Reproductive division between queens and workers
- Parental care (workers) is separated from reproduction (queen)
Solitary reproductive cycle
- Nest -> build cell -> pollen and nectar -> lay egg
- After “lay egg”, the cycle goes back to “make nest” and repeat cycle
social reproductive cycle
- general: Nest -> build cell -> pollen and nectar -> lay egg
- Workers: cycle ends at”pollen and nectar” then cycle starts back at “nest”
- Queen: Stays in “lay egg” cycle and does not do other functions
reproductive cycle for wasps and ants
- Nest -> build cell -> pollen and nectar -> lay egg
- same for bees but replace ‘pollen and nectar’ with other provisions for wasps and ants
How can worker sterility be selected for?
- indirect fitness
- workers are daughters of the queen
- they are raising relatives
Who are the social Hymenoptera?
- some bees
- some wasps (paper wasps, hornets, yellowjackets)
- all ants (none are solitary)
Nesting and the evolution of social behavior
- Nest means opportunity for parent-offspring interactions
- Daughter can stay to help mom rear more offspring (the daughter’s sisters)
explain the social wasps: paper wasps, yellowjackets, hornets
- social hunters
- they are predatory wasps, but hunt with mandibles, not with sting
- Hunt caterpillars, chew up to provision to offspring
- Sting for self/nest defense
- Bigger colonies more aggressive
social wasps - why are bigger colonies more aggressive
- More to defend = more to lose
- The cost of being aggressive are lower with many individuals present
social wasps - explain their ecological importance
- By mid-summer there are huge colonies
- ecologically important source of predation through the control of herbivory (via caterpillar consumption)
explain the Bombus (Bumblebee) life cycle
- mating queens emerge from diapause in spring/summer
- Search for nest sites (often old mouse burrow), fly low
- Forage for food, lay first eggs
- First generations become workers; queen stops foraging
- At the end of the season, males and future queens produced, mating
- Future queen overwinters, everyone else dies
explain the Apis (Honeybee) life cycle
- No solitary state – new colonies established by swarm of workers from old colony accompanying queen to new nest site
- Elaborate communication (waggle dance)
- Honey is used as the bee’s food source to buffer environmental variation
explain the ants
- Diverse and ecologically massively important
- All social – no solitary ant species
- Typically, predators, often the most important of other insect
- Can be de facto herbivores by tending Hemipterans (like aphids)
- Often have morphological castes
ants - Why do you think morphological castes are more common in ants and termites than in social bees and wasps?
- Ants do not have to fly, they only have wings for mating then they drop
- Thus, ants can have bodies that don’t work too well for flying
why is it that natural selection can select for behaviors that favor colony level reproductive success
Indirect fitness
if natural selection selects based on indirect fitness for social insects, what is reproductive success then?
- Reproduction of new colonies
- Colonies founded by new queens, and males that leave the colony to mate with new queens of other colonies
what does it mean for a species to have a division of labor specialization
- the worker’s goal is not to reproduce themselves but to help the colony produce more dispersing reproductive males and queens
- Producing more workers is a means to this end
Advantages of social living
- Increased survival, nest defense
- Cooperation: do things that are impossible alone
- Efficiency: specialization and parallel processing
- Competition: monopolize resources
- Controlled environment of nest
- May store resources for harsh times (e.g., honey)
advantages of social living - cooperation
group hunting
advantages of social living - controlled environment of nest
Social insects can control microclimate (temperature, humidity, CO2, etc.) through nest site choice, nest architecture, and behavior in the nest
advantages of specialization
- parallel processing
- specialization for defense
- morphological specialization
specialization - parallel processing
- “assembly line” vs “individually hand crafted”
- assembly line is less prone to error
explain the superorganism analogy
- Each individual social insect is analogous to cells in the body bc each worker is specialized for a certain tasks even though they are not reproducing
- Same way as an individual’s organs are specialized for certain tasks without reproducing
