Insect Ecology & Conservation Final

Why are there so many insect species?

1. Small size

2. Age

3. Body plan

4. Metamorphosis

5. Exoskeleton

6. Wings

7. Adaptive radiation

What factors contributed to adaptive radiation in insects?

1. Species richness & plant diversity

2. Species richness of resulting insect herbivores

3. Speciation mechanisms

Ideal free distribution

Organisms will enter the highest quality habitat until it is filled, then it is no longer the highest quality- then they will move to the next highest quality habitat until it, too, is filled, and so on

DNA hypothesis

Sex is an adaptation to combat genetic damage

Muller’s ratchet

An asexual population will experience harmful mutation that compound (ratchet), and you will eventually reach a point where these mutations are lethal

Red queen hypothesis

Sex is a genetic adaptation to the variability that particularly long-lived organisms experience from pathogens and parasites

Rate of evolution

Sexual populations can evolve to meet environmental stresses faster than asexual populations

W.D. Hamilton

Proposed the Red Queen Hypothesis

Favorite son hypothesis

In a polygynous mating system, generally all females will be mated, but there is competition between males, so there is a lot of variability in who gets mated in males- only the good males get mates

Parental investment

Any investment in an individual offspring that increases that offspring’s fitness coming at the expense of the parent to invest in other offspring

Optimistic thinking hypothesis

The parent doesn’t know what the environment’s future conditions will be; if it’s good, then there may be enough resources to raise all of the offspring

Facilitation hypothesis

Parents put food for the offspring in the form of offspring; “trophic eggs”

Replacement hypothesis

Making more offspring than are going to survive in case some are lost

Competition hypothesis

Making more offspring than there are resources so they fight and the strongest survives

Why should parents abandon young?

• If continuing to invest isn’t going to produce good results

• If a more desirable male comes along

• If resources are increasing

Anisogamy

The difference in the investment in gametes (males vs females); males can make much more sperm than females can make eggs

Reciprocal coevolution

Evolutionary arms race between one insect and one plant

Diffuse coevolution

Community, not individual, of herbivores drives the chemistry of a plant

Sequential coevolution

Insect evolution follows changes caused by plant-plant competition

Benefits of specialization

1. Minimizes interspecific competition

2. Easy to recognize and find food

3. Use plant toxins to protect insects from predators/pathogens

4. Synchronization of life history with plant phenology

5. Evolution of crypsis

6. Minimization of metabolic costs

Dollo’s Law

States that evolution of eusociality is irreversible- but this has been proven to be false

Superorganism

Comparisons between metazoan organisms and honeybees revealed they behaved similarly, but the metazoans are clones, so they’re helping their own genes succeed, whereas honeybees should be competing to spread their genes, but they aren’t

Group selection

Under specific conditions, “selfish” groups will go extinct faster than “altruistic” ones

Handicap principle

If you act altruistically and survive, you will be well-fed, reproduce a lot, and overall further your genes

Kin selection

Selection for a trait favoring the survival of close relatives presumably at a cost to your own fitness

Parental manipulation

It’s better to convince your first brood to stay and help rear the second, as you’re more related to both broods than you would be your first brood’s offspring

Subfertility hypothesis

Several queens start a nest at the same time but aren’t equally fertile; studies show this is untrue

Problems with kin selection

1. Multiple matings - reduces relatedness of sisters

2. Nonsocial hymenoptera

3. Diploid, eusocial termites

4. Polygyny - multiple queens

Caterpillars are the best food for birds because they’re…

1. Soft

2. Large

3. Nutritious

4. Low % chitin

5. The best source of carotenoids

Ecological responsibilities of a landscape

1. Support food webs

2. Sequester carbon

3. Clean and manage water

4. Support pollinators

How to help insects

1. Shrink lawns

2. Plant keystone species

3. Use yellow lights

Selection pressures favoring maternal care

1. Stable environment

2. Physically harsh environment

3. Specialized food resources

4. Predation