Post on 14-May-2018
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Announcements• Lab quiz next Monday• Insect collections to be returned in lab• Tips for a good collection
– Insects pinned and labeled asshown in guidelines
– Enough insects collected– Good presentation of specimens
Nice collections
Last lecture• Kinds of sexual selection
– Intrasexual• Male male competition
– Contest competition– Scramble competition
• Sperm competition– Intersexual- female choice
• Reproductive conflict between sexes• Outcomes of sexual selection• Case of willow leaf beetle
Questions about leaf beetlestudy?
Ovipositor Structure Ovipositor Modifications
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Ichneumon Insect reproduction• Types of offspring produced
– Oviparity-eggs travel down oviduct, arefertilized, and laid
– Oviviparity- eggs incubate insidereproductive tract of female beforelaying
– Viviparity- ‘live’ birth, where larvaedevelop inside female
• Parthenogenesis• Hermaphroditism in insects• Effects of vertically transmitted bacteria on
reproduction
Viparity: Egg laying• Oviparity
– Laying initiates egg development
Viviparity– initiation of egg developmenttakes place in female
Parthenogenesis• Females produce viable unfertilized
eggs• Found in nearly all insect orders
Leaf beetle genus Oreina• Found in Europe• All three reproductive
strategies found inone genus
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Parthenogenesis• Types
– Obligatory– Facultative
• Seasonal in aphids– Asexualreproductionduring summer
– Sexualreproduction inSpring and fall
Variation in reproduction
larvaeO. variabilis
eggsO. elongata
larvaeO. cacaliae
Parthenogenesis in Hymenoptera
• Sex determination– Haploid = male– Diploid = female
• Mechanism– Female letssperm fertilizeeggs, female
– With nofertilization,male
Bumblebee life cycle Ant life cycle