Animal AdaptationsArthropods

Biological Control (Integrated Pest Management)

Animal Adaptations

Correlations of life choices with structural and physiological

changes. Things to think about

Why choose? = competition – or avoiding it.

Reproductive cycles

• All adults are diploid – haploid cells are egg and sperm only.

• Egg almost always bigger (heterogamy)• Primitive – both egg and sperm released

for external fertilization• Advanced – egg retained, sperm released• The fertilized egg (outside body) or a

structure to produce eggs and sperm can be dispersal phase.

Coral life cycle. The medusa (like a jellyfish) is diploid, but male or female or both. Meiosis in it produces eggs and sperm – planula is a dispersal phase

Issues with reproduction (for each choice- what are the pros and cons.)

1. How many young?? (How many needed??)

2. Size of eggs?

3. Altricial vs precocial

4. Parental care

5. Retain egg in mother until hatching.

What affects the choices?

• R vs K species – life span• Life history – are parents around??

http://www.bioone.org/action/showFullPopup?doi=10.1642%2F0004-8038%282003%29120%5B0941%3AEOALCO%5D2.0.CO%3B2&id=_e1

Sessile vs motile?

Which systems affected?

What limits placed on where you live- why?

Sessile living: sponge, corals,

Reproduction: sexual, motile sperm find egg, but also cloning (asexual) plus regeneration

Food; in water, mostly ocean (why?)

Dispersal: larvae with flagella.

Protection: regeneration, spicules

Symmetry: assymetric vs

radial, bilateral

Which leads to what systems?

Nerves and senses and brain concentration.

One of the major senses: Light sensitivity

Nearly all cells have it – goes back to bacteria.

Higher animals – special light sensory devices – function

detect light – use for clocks – telling seasons, etc.

detect movement only - protection

identify shape; - leads to memory.

How to take an image – break it into bits of information – transmit to brain for storage and processing?

Note: diurnal vs nocturnal

diurnal ; shape perception = eyes

nocturnal: -vision – see movement, not shape.

shape perception in dark = radar, sonar – bats and porpoises

What if you are motile and can’t find a mate?

Under what conditions is this likely to occur??

Parasites in body

Whiptail lizards, among others

Parthenogenesis = egg develops without

fertilization.

Why here? (are males that repulsive?)

Multicellularity - size

What systems required to gain in size? Why?

Circulation, respiration, excretion, skeleton

Skeleton – a requirement of size

External

Internal

Hydrostatic

Limitations of each?

Hydrostatic

Muscles compress compartments – push the worm forward. Setae(spines) hold portions of body to ground.

Note cross – sectional diameter.

respiration

Aquatic

• Through skin if small

• Gills if bigger (large surface area in water)

Terrestrial

keep wet gills

lungs

insects – spiracles.

Large surface area in contact with environment – skin respiration

Fish gill structure – large surface area

Crab gills – feathery under surface for protection

Terrestrial vs aquatic:

Which systems affected?

As with plants.

How to avoid drying out

How to breathe – get oxygen.

Feeding types:

Filter feeder

Herbivore

Carnivore

Omnivore

Specialized food; molluscs, fish, ants,

Which feeding type leads to:

more active life?

being clever?

larger population size?

Cold vs warm blooded: - what are the advantages, disadvantages of each?

What conditions might favor the development of warm bloodedness?

Figure 40.9 Ectotherms and Endotherms React Differently to Environmental Temperatures (A)

Mammals as maxitherms.

How to deal with harsh conditions?

Like a plant: - survive as egg (seed)

- adapt (fur, evaporative cooling, etc)

New means:

-migration – avoid bad conditions

-hibernation

Allen’s rule; larger extremities in warmer climates

Arthropods

beetles Butterflies and moths

Bees, ants, wasps

Trilobites – stem group, marine

External skeleton

Metamorphosis vs incomplete metamorphosis.

Why insects so successful?

• r species – adaptable

• extreme specialists

• live in water, land and air

• flight

• excellent nervous systems

• life cycle; larval feeding.

• all food types, plant, animal, scavenger, predator, etc.

• many have social behavior

Insects as pests

• diseases – carriers of protozoa, bacteria

• crop pests – direct effects or carriers of fungi, etc.

How to deal with insects

• Pesticide -Insecticide: a chemical that kills all insects, but they develop resistence, and some like DDT harm other organisms

• Biological control: Know your enemy and find a chink in their life cycle; four examples. Problem – kills only the target insect.

Find a natural parasite or disease of the pest.

Breed it, and release it into the environment

Here parasitic wasps lay eggs on caterpillars, kill them so they won’t eat a crop.

Screw worm fly

Screw worm eradication

• Females only mate once

• Can’t tell difference between sterile and fertile males

• Can sterilize with radiation

So: knock the population down with pesticide

release a lot of sterile males 10-100 for each fertile male

get rid of flies in one year.

prevent reintroduction

Moth and caterpillar crop pests

Females release a pheromone to attract males.

Synthesize the pheromone

Place in traps around the crop

Poor female left forlorn in the field.

Life cycle – juvenile hormone absence allows pupa formation.

So synthesize the juvenile hormone, spray on crop

Caterpillers never metamorphoze, never pupate.

No adults formed, no increase in population.

Integrated Pest Management

• Use a pesticide to knock down the insect population

• Use a biological control to finish it off.

New technique – Bt corn etc.

Insert the genes for a bacterial toxin into a plant crop (plus the genes to turn it on, etc.

Bt is a bacterial toxin against moth and butterfly caterpillers.

To kill a susceptible insect, a part of the plant that contains the Bt protein (not all parts of the plant necessarily contain the protein in equal concentrations) must be ingested. Within minutes, the protein binds to the gut wall and the insect stops feeding. Within hours, the gut wall breaks down and normal gut bacteria invade the body cavity. The insect dies of septicemia as bacteria multiply in the blood. Even among Lepidoptera larvae, species differ in sensitivity to the Bt protein.

Why are biological controls good?

• kill pest species only

• pest cannot develop resistence to them

• no chemical residue in water supply, etc.

So why are chemical pesticides overwhelmingly preferred??

By Farmer:

• don’t need to know your enemy – just spread the chemical

• chemical kills any and all pests immediately – no lag time.

• often relatively cheap (why? See below)

By the Industry (Dow and Monsanto Chemical)

• bigger market; works on any crop

• can patent the product (unique chemical created by company

• If resistence, make a new chemical (planned obsolescence)

•Result: only crops that are big (corn) might use biological controls

• not used for small volume crops or in undeveloped countries

• government must subsidize development.