VL 11 Flashcards
Eusociality
Overlapping generations in shared nest (parents, worker offspring, offspring of offspring)
Cooperative brood care
Non-reproductive worker caste
Low degrees of sociality
some parental care - giant water bug
communal living - eastern tent caterpillars
cooperative care of young - orchid bees + paper wasps
Solitary vs. eusocial bees
Eusocial:
Honey bees
Stingless beees
bumble bees (= are not morohologically different, queen is just bigger (exception) but are stille usocial)
Solitary examples: (may have some social traits but are solitary, 95% of total bee species)
Mason bees
Mining bees
Leafcutter bees
What are the ecological differences between solitary and eusocial bees?
Overwintering - moving to inside-outside in bee hive, queen in middle, bumblebees only queen overwinter, restart whole colony in new year
Generalist / specialist on flowers - solitary = specialist, social = generalist
Parasites, diseases and parasitoids - solitary bees die, in social bees other bees can help with cleaning but danger of spreading in hive
Investment in young - higher survival rate in social bees as there is more time that is invested in young
Where / how they nest - solitary bee has nest in ground
Bumblebee colony’s life cycle
1) Queen overwintering
2) Queen foraging
3) Nest installation
4) Colony development, first set of workers = during first weeks queen invests all in the eggs, only chance of survival
5) Flower visitation, startung of growing new queens (genetically different)
6) Mating
Hamilton’s inclusive fitness theory
Kin selection theory
Why are some species altruistic? ie. non-reproductive workers providing food / defence / brood care
Altruism = fitness negative to one individual in providing a fitness benefit to another
If they are closely related, they are still helping shred genes pass on
Haplodiploidy and relatedness
see page 8
All eusocial hymenoptera are haplodiploid (ants, bees, wasps)
Queen (AB) + Male (C)
-> Male offspring (A), Male offspring (B)
-> Female offspring (AC), Female offspring (BC)
more probable to have new queens than males to mate with queen, much less probable that male will successfully mate and pass on genes
Haplodiploidy hypothesis
Hamilton’s inclusive fitness theory fits in eusocial Hymenoptera due to relatedness - females are more related to their sisters than their own offspring
Benefits of eucociality
Fortress defence
Life insurance
Many different specializations - efficiency, splitting the workload
Low success of genes for solitary species
Gaining and losing eusociality
Closely related species of Halactid sweat bees have gained and lost primitive eusociality throughout their evolutionary history
Solitary sweat bees have higher failure establishing nests and produce fewer broods
Eusociality requires suitable environmental conditions to get through 2 generations
Polymorphic species of sweat bees are socially flexible (can develop and then be social or solitary depending on environmental conditions)
Why are termites eusocial?
Diploid, so not more related to fellow workers
When evolved eusociality, lived in confined space under bark - remain across generations for protection
Hemimetabolous development - workers are nymphs in arrested development
Possible benefit = inheriting natal nest (if king and queen die another can take place)
Reproductive king and queen are the first targeted in inter-colony attacks
Founding a new colony is of equal difficulty to probability of inheritance - 99% fail. When colony size increases, more chance of offspring developing as alates (winged forms) and moving out
Termite heat regulation
similar to leaf cutter ants in nesting and farming the fungus
Fungus farming termites (Macrotermitidae) culture fungi (Termitomyces) that require specific temperatures
Regulate heat in the nest using chimneys and channels
Pores in walls exchange CO2
Communication in social insects
More important the larger your colony
Pheromones: Alarm, attraction, recruitment and
assembly, trail marking
Cuticular hydrocarbons: recognition of nest-mate, caste, fertility
Detect signals with sensilla on antennae and legs – specialized in different castes
Communication: Resource gathering - tha waggle dance
European honey bees (Apis melifera) dance to communicate a resource location
Recruited bees watch, then go to the location
Only form of ‘symbolic communication’ in invertebrates – representing
information in a new form
Figure of eight movements + wing vibration and ‘waggling’ abdomen
Dancers emit pheromones to draw attention
Communication: resource gathering - other forager communication
Bumblebees leave secretions on flowers that scent-mark, do excited runs and release recruitment pheromone in hive to stimulate foraging
Stingless bees use scent markers, trails and excitatory sound and visual cues
Uncommon in eusocial wasps, but hornet Vespa mandarinia scouts will mark bee
nests with pheromone
Ants and termites lay a chemical trail on the way back to nest, or in small colonies have tandem running, to show a naive ant the way
Ants regulate number of foragers through antennal contact
