Week 9 Flashcards
What are the phylogenetic breakdown of insects?
Phylum- Arthropoda
Clade - Mandibulata
Sybphylum - Hexapoda
Class - Insecta
What trait means insects are apart of the phylum Arthropoda?
Hardened chitinous exoskeleton that moults
What trait means insects are apart of the clade Mandibulata?
Antennae and body divded into head, thorax and abdomen
What trait means insects are apart of the subphylum Hexapoda?
3 pairs of jointed legs
What trait means insects are apart of the class Insecta?
2 pairs of wings (can be secondarily lost)
1 pairs of antennae
How many species are insects?
> 1 million species compared to all other animals ~650,000 species (40%)
How many species of beetles are there?
Approximately 380,000 (23% of all species)
Why are insects important?
Important for ecosystem services such as:
Pollination
Dung removal
Pest control
Carrion breakdown
Food
How important are insects economically?
> 57 billion annually in the US
How have insect populations been over last 50 years?
Up to 75% decline in the past 50 years
What traits in insects are being used as inspiration?
Dragonflies flight
Be uncrushable
Bees effective communication
Termintes building nest that are air conditioned
What is biometrics?
The tranfer of ideas and analogues from biology to technology
What is an example of a biometric?
Tribots, inspired by trapjaw ants
What are examples of the cultural significance of insects?
1338 BCE, commemorative Egyptian scarab
Pet cricket & gourd container watercolor byQi Baishi(1864–1957)
The song Flight of the Bumblebee
What is an overview of monarch butterfly navigation?
Up to 3000 km travelled
No single individual completes the trip
4 generations in the complete annual cycle
What is an overview of learning and memory in bumblebees?
Bees have to navigate complex spatial environments - need to remember floral resources
Bees can be taught simple tasks in the lab And can learn by watching other bees (or bee-shaped models)
Seen being able to play simple football and pull string to get to reward
What is an example of rentention of memory in moths?
Retention of moth memory through metamorphosis
Tobacco hornworm caterpillars were trained to avoid the scent of ethyl acetate
77% of adults still avoided it once they had undergone metamorphosis
What is an exmaple of parentla care in burying beetles?
Both parents care for offspring
But also sometimes eat them, or desert them - unkown why they choose which behaviour
What is the goal of behavioural ecology?
“explain the survival and reproductive value (i.e. the evolutionary significance) of behavioural traits
Why are studying insect useful?
Many fascinating behaviours
Useful tractable models in behavioural ecology
Many offspring produced
Can measure lifespan and lifetime reproduction
Large sample size
What is aggresion and weaponry in behaviour?
Sexually selected traits constitute some of the most eye catching morphologies
In lots of species, one sex (typically but not always the male) invests in weapons which are used in contests
What are examples of insects investing in weapons for mating?
Stalk eyed flies
Coreids (leaf-footed bugs) - large rear legs with spikes
What is an example of fighiting being costly?
Thasus neocalifornicus (Coreid) - wing tears
Wing tears increase resting metabolic rate and decrease flight ability
Bigger tear bigger difference
How did scientists manipulate the outcome of Thasus neocalifornicus fights?
Giving bugs more defensive armour increases their likelihood of winning contests
Armoured bugs on area damaged meant 1.6x more likely to win
What is an example of different species of same species fighting with similar but different methods?
Rhinoceros beetles
Trypoxylus dichotomus - prob then twist to wrestle rival
Dynastes hercules - Scissor motion
Golofa porteri - Stabby motion
What are the evolutionary pressures meant to decrease injury in rhinoceros beetles?
Trypoxylus dichotomus - resistant to downwards, sideways and twisting motion
Dynastes hercules - resistant to downwards and sideways but vulnerable to twisting motion
Golofa porteri - resistant to downwards and sideways but vulnerable to twisting motion
How likely is injury in rhinoceros beetles when fighting for mates?
17% injured
4% severly injured
What can cause males to fight for females when risks present?
Males must weigh up the costs and benefits of engaging
Fight escalation is more likely when males are similar in size
And when females are present (i.e. payoff is greater)
And if they’ve won before (the winner-loser effect)
What is the winning effect?
Winning fights induces short term hyperaggression, seen in crickets
Time limited effect
What mediates the winner effect?
Mediated via the action of octopamine (equivalent role to noradrenaline in mammals), nitric oxideand serotonin
What happens during the winner effect?
Winning releases octopamine
Acts as a reward therefore more likely to fight
What is the balance found in insenct males for weapons for fighting other males?
Big weapons help males win fights but also increase the risk of predators
What is a common antipredator strategy in insects?
Autotomy
What is autotomy?
‘The self‐controlled loss of a body part at a predetermined breakage location’
What are other examples of animals that can undergo autotomy?
Nematoida
Platyhelminthes
Mollusca
Craniata
What can vary with autosomy?
Autotomize is widespread across hemipterans
Some species drop their legs faster than others
How common can autosomy be found?
It’s common to find individuals missing one (or more!) limbs in the wild
What is a secondary advantage of autosamy?
Autotomy not just enables escape but also increases survival after injury - seen in experiment with species of coreids, automy survival was 85% compared to 60% when injured and 72% in control
How does autotomy impact males fighting competition?
Autotomy doesn’t affect how likely males are to engage in fighting
But it does increase the likelihood they lose
If males cant fight, how can they produce offspring?
Invest in sperm production rather than weaponary - more competitively sucessful when matings do arise
Seen in dung beetles
Is there a trade-off between weapons and testes?
Autotomy during the fourth instar associated with 15-39% greater adult testes mass
Seen in coreids
How was the tradeoff between weapons and testes investigated?
We can use autotomy (a natural antipredator behaviour) as a way to look for trade-offs by removing weapon
What is the relationship between weapon autosomy and testes investment?
The earlier autotomy limb loss occurs, the bigger a male’s testes are
Seen in coreids
What behaviour can autosomy impact with mating?
Autotomy induces an increase in average mating duration
Seen in coreids
How can behaviour and morphology interact?
Morphology - decrease in reallocation after adulthood as resources avaliable decrease as well as developmental flexability
Behaviour - potentially maximase the pay off of larger testes
Seen in coreids
What are examples of plasticity of reproduction allocation in insects?
Adjust ejaculate size based on female mating status, fecundity, and age (Lupold et al. 2010)
Produce more sperm produced in response to the presence of rivals (Moatt et al. 2014)
Grow bigger testes if reared at high larval densities (Stockley & Seal 2001)
Grow bigger testes if hear adult males (Bailey et al. 2010)
What tradeoffs are there in reproduction?
When should they fight?
How much should they invest in weapons vs testes?
How much should they risk predation for mating opportunities?
How many risks should they take?
