Lecture 1- Introduction & Insect Ancestry Flashcards
What phylum are insects part of?
Arthopods
What are the 4 main classes of arthropods?
Trilobites (extinct)
Crustacea (extant)
Chelicerates (extant)
Uniramia/ insects (extant)
What is an insect?
No simple definition.
Usually has 6 legs at a point during life.
Body divided into 3 distinct regions- thorax, abdomen, head.
Most adult forms have two pairs of wings on thorax.
Rule about flying invertebrates?
If it can fly it’s an insect.
Insects only invertebrate that can fly
Why are insects important?
Part 1- number of insects
1 million described species (between 2-30 million un-described)
80% of all animal species on planet
Diversity is not reflected in natural history text
They are ecosystem engineers
Ants are predominant animal biomass in tropical forests
What is an Ecosystem Engineer?
It structures environment to suit its needs. This has profound effect on occurrence, abundance and spatial pattern of other species
Case study humans impact on insect diversity/ biomass
Hörmann et al 2017
27 year study on change in insect biomass over time
In Germany over 63 different nature reserves with 96 different locations over the reserves
Set up malaise traps to catch flying insects
76% seasonal decline in biomass.
Important as looks at all insect species
Can’t pinpoint cause but weather, land use and habitat characteristics cannot explain the decline
Why are insects important?
Part 2 - benefits for man
Good model organisms in biology (e.g. drosophila melanogaster)
Flowering crops are pollinated by insects
Act as biological control agents providing economic benefits
Why are insects important?
Part 3- negative for man
600 million people affected by insect vectored diseases
These also affect livestock
Attack crops (15% lost worldwide) stored products (grain) and housing (timber) affected.
What is a living fossil?
A living fossil is an extant taxon that has remained unchanged since its time of origin
Examples of living fossils
Nautilus
Horseshoe crab
INSECTS
What’s the most abundant insect fossil?
Palaeodictyoptera
Found in the Carboniferous
Palaeodictyoptera facts
Palaeo - old Dictyoptera- cockroaches Distinct head + antennae + compound eye Thorax has 2 pairs of wings Elongated 11 segmented abdomen + cerci Not active flyer as long broad wings coupled with long cerci suggest was a glider that glides from treetops
What are the only modern groups found in the Carboniferous?
Mayflies- Ephemeroptera
Dragonflies- Odonata
Mayflies - Ephemeroptera
Ephemero - short lived
Ptera - wings
