entm exam1

How are biological organisms classified?

• Taxonomy:

  • The science of describing, naming and classifying biological organisms into a structured hierarchy

  • How to identify: morphology, molecular genetics

What do family trees reveal?

• Relationships among the same organism (i.e. taxon)

What do phylogenetic trees reveal?

• Visual representation of the relationship between species, taxa, individual, population, etc.

• Branching: represents evolution of a lineage/ speciation

• Trace unique history and patterns of shared ancestry and reveal gains or losses of morphological trait and/or genetic information

What does parsimony mean?

• The best evolutionary tree is the one that requires the smallest number of character changes to explain the observed data

What does Dear King Philip Came Over For Good Soup stand for?

• Mnemonic for the hierarchical order of taxa

• Domain - Kingdom - Phylum - Class - Order - Family - Genus - Species

What traits of a species?

• Different species cannot interbreed

• Different species are on independent evolutionary paths

What is the Superhylum Ecdysozoa?

• Domain: Eukarya, Kingdom: Animalia, Superphylum: Ecdysozoa

• Contains 8 Phyla

• Animals grow by ecdysis, or molting exoskeletons

What are the characteristics of Phyla Nematoda & Nematomophora: “round worms” and “horsehair worms“?

• Superhylum Ecdysozoa

• Long cylindrical body

• Head radially symmetrical

• Gas exchange via diffusion

• Nematoda have amphids (primary chemosensory (smell and taste) organs), Nematomophora do not

• Round worms are typically microscopic while horsehair worms are much larger (10-100+ cm)

What are the characteristics of Phyla Loricifera, Kinorhyncha, & Priapulida?

• Superhylum Ecdysozoa

• Chitinous cuticle (molted)

• Rings of scalids on the introvert

• Flosculi

• Two rings of introvert retracts

What are the characteristics of Phylum Onychophora: “walking worms”?

• Superhylum Ecdysozoa

• Antennae

• Lobe-like legs (hollow, no joints)

• Trachea, spiracles

• Open circulatory system

• Chitinous exoskeleton

What are the characteristics of Phylum Tardigrada: “water bears”?

• Superhylum Ecdysozoa

• Antennae

• Legs without joints, but with claws

• Gas exchange via diffusion

• Excretory organs

• Sucking, muscular pharynx

• Chitinous cuticle (molted)

What are the characteristics of Phylum Arthropoda: “jointed foot”?

• Superhylum Ecdysozoa

• Bilaterally symmetrical

• Exoskeleton

• Open circ. system

• Trachea or gills

• Multiple body segments

• Jointed appendages

What are the characteristics of the Subphyla of Arthropoda?

• Domain: Eukarya

• Kingdom: Animalia

• Superphylum: Ecdysozoa

• Phylum: Arthropoda

What are the characteristics of Subphylum Trilobita?

• 500-600 Million Years ago

• Flattened body

• Many legs

• Crustacea filled niche

What are the characteristics of Subphylum Chelicerata?

• Spiders, scorpions, mites, ticks, sea spiders, horseshoe crabs

• They have chelicerae (the first pair of appendages flanking the mouth in arthropods of the subphylum Chelicerae) and pedipalps (are the second pair of forward appendages in chelicerates)

• Four pairs of legs and simple eyes

• Not insects

What are the characteristics of Arachnids?

• Domain: Eukarya, Kingdom: Animalia, Phylum: Arthropoda, Subphylum: Cheliverata, Class: Arachnida

• Spiders, sun spiders, ticks, whipscorpion, scorpion

What does the subphylum Crustacea consist of?

Lobsters, crabs, shrimps, barnacles, isopods

What are the characteristics of Subphylum Myriapoda?

• Millipedes, centipedes

• Bilateral symmetry

• Antennae

• Uniramous

• Numerous pairs of legs

What are the characteristics of the Subphylum Hexapoda?

• Protura (cone-headed soil organisms), Diplura (two-pronged bristletails), Collembola (springtails), Insecta

• While all insects are hexapods, not all hexapods are insects

• Protura, Diplura, Collembola all have INTERNAL MOUTHPARTS (Entognatha) (Insects have EXTERNAL mouthparts)

  • Ex. Entognathous mouthparts of springtails: retracted within the head capsule

Evolutionary success of insects

• More insect species than any other life form due to:

  • Tough, protective exoskeleton

  • Small size

  • Metamorphosis

  • Wings (ability to fly)

  • Sociality (some bees, some wasps, all ants and termites)

  • High reproductive rate (frequent reproduction x short development time= insects are adaptable)

Parthenogenesis

• (high reproductive rate)

• Asexual reproduction in which growth and development of embryos occur without fertilization

• Ex. Bees and unfertilized eggs and aphids and clonal reproduction

Sociality in Insects

• 1. Cooperation

• 2, Overlapping generations

• 3. Division of labor

Phenotype

• Phenotype= Genotype x Environment

  • Phenotype: Observable characteristics of how an organism looks

  • Genotype: Genetic information

  • Environment: Environmental conditions where the organism lives and grows

Genetic Mutation

• Main mechanism of evolution

• Changes in DNA/ genetic code

• Random mutation->genetic variation

  • Phenotypic variation due to genetics: is heritable (i.e. you get genes from your parents and you will pass on your genes to your offspring)

Gene flow

• Main mechanism of evolution

• Movement to new habitats

Genetic Drift

• Main mechanism of evolution

• Random events change populations

Natural selection

• Main mechanism of evolution

• The process whereby organisms better adapted to their environment tend to survive and produce more offspring

• Organisms with most favorable traits survive and reproduce

Natural selection influences

• 1. Individuals of a species do not reproduce equally

• 2. Most populations are stable in size

• 3. Resources are limited

• 4. Individuals exhibit phenotypic variation (Phenotypic variation required for natural selection!!!!!!)

• 5. Variation between individuals must be inherited

• Phenotypes that provide a fitness advantage will be positively selected:

  • Higher survival and/or more offspring

Exoskeleton limitations

• restrictive to growth -> so there is a need to shed it once they get too big for their “skin” to gain another (sometimes head is lost)

Molting

• Ecdysis

• shedding of old exoskeleton to form a new, larger exoskeleton

• Regulation of molting: hormonal control

  • Sensory input (exoskeleton too small) -> Neurons secrete brain hormone (triggers a cascade stimulating the prothoracic glands) -> molting hormone is secreted (ecdysone)

Metamorphosis

• the process of transformation from an immature form to an adult form in two or more distinct stages

• Egg-> Nymph-> Adult

• Triggered by juvenile hormone

Ametabolous Metamorphosis

• Most primitive adults look basically like really big nymphs (immature, juvenile stage of an insect)

• all life stages in same habitat (rare)

• Most primitive trait

Hemimetabolous Metamorphosis

• Incomplete metamorphosis- Adults look like nymphs except adults have wings

• egg-> nymph->  nymph->  nymph-> adult (sexually mature)

• Wing pads present in older juveniles

• Wings present in adults

• all life stages tend to be in similar environments and eat similar foods

Holometabolous Metamorphosis

• Complete metamorphosis- adults look very different from larvae

• Larvae are frequently in very different habitats and eat different foods from adults

• Most derived trait

Holometabolous Insects

• Complete metamorphosis

• Egg -> 1st instar larva -> 2nd instar larva -> 3rd instar larva -> …. -> pupa -> adult (winged and sexually mature)

• Instar: larval developmental stage between molts

• Stadium: time between instars

• Diapause: A period of arrested development

Chitin

• Exoskeleton is made of chitin

• Long-chain polymer of an N-acetylglucosamine, a derivative of glucose

• Characteristic component of the exoskeletons of arthropods, such as crustaceans and insects

Insect exoskeleton components

• Chitin

• Pit/ pot

• Setae

• Epicuticle

• Procuticle

• Epidermis

• Basement membrane

• Insect cross section

Suture

• fold in the exoskeleton

Procuticle

• Exocuticle (exo: outer)

• Endocuticle (endo: inner)

• Epicuticle and exocuticle are shed as insects grow

Insect Cross Section

• Exoskeleton folds internally

• 1. Points for muscle attachment

• 2. Provide structural reinforcement

Ectognatha

• Taxonomic group synonymous with insecta

• External mouthparts

“Classic” mouthparts

• Normal sized mandibles for chewing

• Hypopharynx: tongue-like structure

“Modified” mouthparts

• Enlargened mandibles

• Modified maxilla

• Bees: modified into “tongue-” like mouthpart

• True bugs and mosquitoes: modified into piercing-sucking

Ommatidia

• (singular ommatidium): Compound eye; makes up the whole compound eye

Ocelli

(singular ocellus): Simple eye; on top of head- detecting light

Stemmata

• (Singular Stemma)

• Immature holometabolous insects

• Side of the head

“Classic” antennae

Scape, pedicel, flagellum

Receptors

• Part of antennae

• Allow insects to detect and perceive the world

Chemoreception (Pheromones)

• Trail-making

• Aggregation

• Sex pheromones

Mechanoreception (Vibration)

• Receptors stimulated-> neurons fire-> information sent to the brain

• Johnston’s Organ: located in the pedicel of the antennae

  • Detects vibration (air movement and sound) impacting the flagellum

  • Helps flying insects manage flight

Insect Tagma

• Head, thorax, abdomen

Head

• External mouthparts

• Eyes

• Antennae (receptos)

Thorax

• Wings, legs, tympanum (or on abdomen)

“Modified” wings

• Orthoptera: tegmina

• Coleoptera: elytra

• Hemiptera: hemelytra

• Lepidoptera: ex. Butterflies’ scaly wings

• Diptera and strepsiptera: halteres

  • Flap rapidly

  • Help with rotation and orientation

Halteres

• Diptera and strepsiptera (bees, flies)

• Flap rapidly

• Help with rotation and orientation

“Modified” legs

• Cursorial: running

• Raptorial: grabbing

• Saltatorial: jumping

• Natatorial: swimming

• Fossorial: digging

• Corbicular hairs: “pollen basket”

Tympanum

• Tympanal organ: a membrane stretched like a drum-head

  • Detects sound

  • On legs (tibia) or abdomen

Prolegs

• Abdominal legs (ex. caterpillars)

Abdomen

• Functions: respiration, reproduction, digestion, excretion

• Spiracles

• Cerci

• Ovipositor

  • Female organ that lays eggs/ implants them

  • “Modified” ovipositor: stinger (ex. bees)

• Aedeagus

Tagmosis

• Evolutionary process of body segments fusing to form body regions

Circulatory System

• Movement of blood

• Hemolymph

  • Open circulatory system: hemolymph bathes the tissues and is not confined to vessels

  • Defensive function of hemolymph: blister beetles, ladybug beetles; reflexive bleeding

• Dorsal Vessel: a simple pump maintains flow of hemolymph

Respiration

• Gas exchange

• Spiracles

• Trachea

Digestion

• Food breakdown

• Alimentary canal: long, muscular, enclosed tube that extends from mouth to anus (foregut-> midgut-> hindgut)

• Fat Body: food storage, metabolism/ detoxification, eating and pooping

Excretion

• Waste removal

• Malpighian tubule: insect equivalent of a kidney-> getting rid of what you don’t need and keeping what you do need

  • Hemolymph travels into the tubules

Nervous System

• System processing

• Ganglia (singular: ganglion): mass of nervous tissue usually responsible for control of an individual segment of the body

Reproduction

• Producing offspring

• Mating: mating attempts may or may not lead to production of offspring

  • Mating behavior example: tree cricket calling/making a noise to call for female

Spermataphore

• Produced by male accessory gland

• Protein rich capsule that packages sperm

• Ensures female will fertilize

• Female may eat after mating

Ootheca

•  Produced by accessory glands: egg shell that protects the offspring

Spermatheca

• Place where females can store sperm for long periods of time

  • Ex. Queen bee fertilizing bees when necessary

Insect vs. Human Anatomy

• Insect vs Vertebrate Blood

  • BOTH transport nutrients, hormones, and wastes

  • ONLY vertebrate blood transports oxygen and removes carbon dioxide- insect blood does not

• Trachea in humans and insects

• Ganglia in humans and insects

• Kidneys in human and Malpighian tubule in insects

Artificial Selection

• The process whereby organisms are preferentially bred because of desired traits

Monophyly

• derived (=adapted) from a single common ancestor

  • A monophyletic group: only and all closely related species

  • A monophyletic trait: shared amongst related species

Polyphyly

• derived from multiple common ancestors

  • A polyphyletic trait: characterize organisms that are not a part of a natural group/ different groups of organisms evolved the same trait independently (convergent evolution)

Plant-insect coevolution

• Coevolutionary arms race: cycle of adaptation and counter-adaptation where plants evolve defenses to avoid being eaten, and insects evolve countermeasures to overcome them

• Herbivores: Insects evolved mechanisms to exploit plants as food resources

• Plant Defense: Plants evolved counter-mechanisms to protect against damage

Insect Herbivore Diet Breadth

• Specialist: herbivore feeds on plants in 1 family

• Generalist: herbivore feeds on plants in many different families

Insect Herbivore Diversity

• External chewers

• Skeletonizers

• Shelter builders

• Piercing-sucking herbivores

• Internal feeding- Borers

• Internal feeding- Galls

External Chewers

• Leaves -> folivores

• Flowers -> florivores

• Fruits -> frugivores

• Seeds -> granivores

• Roots -> root feeders

Skeletonizers

• Lepidoptera (catterpillars etc.)

• Eating just the soft tissue of leaves

Shelter Builders

• Leaf rollers

• Leaf tiers

• Leaf tents

Piercing-sucking herbivores

• Puncture plan vasculature and suck out fluids

Internal feeding- Borers

• leaves-> leaf miners

• Stems

• Flowers

• Fruits

• Roots

Internal feeding- Galls

• Feeding damage causes plant to produce tumor that insect herbivores live inside while feeding and growing

Key Agricultural Insect Pests: Orders

• Order Coleoptera: beetles

• Order Diptera: true flies

• Order Lepidoptera: butterflies, skippers, moths

• Order Thysanoptera: thrips

• Order Hemiptera: true bugs

Order Coleoptera

• Elytra

• Hind wing membranous

• Chewing mouthparts

• Antennae very variable

• Key Agricultural Insect Pest

Order Coleoptera: Family Chrysomelidae

• Leaf beetles (striped cucumber beetle, spotted cucumber beetle, western corn rootworm, flea beetle)

• Major crop pests

• Colorado potato beetle: quickly develops resistance to insecticides

• Key Agricultural Insect Pest

Order Coleoptera: Family Curculionide

• Weevils, snout beetles, bark beetles, ambrosia beetles

• Distinctive morphology: Long snout and club-like antennae

• Serious pests with narrow host range

• Key Agricultural Insect Pest

Order Lepidoptera

• “butterflies, skippers, moths”

• Scales on wings, body, and legs

• Mouthparts modified for sucking/siphoning (Proboscis)

• Key Agricultural Insect Pest

Order Lepidoptera: Family Noctuidae

• Owlet moths, underwing moths

  • Larvae are called cutworms

• Largest family in order

• Key Agricultural Insect Pest

Order Thysanoptera

• “thrips”

• conical , asymmetrical mouthparts (rasping)

• Tips: hairs on wings, long thin “torpedo” body

• Key Agricultural Insect Pest

Order Hemiptera

• “true bugs”

• Common feature: sucking mouthparts

• Mandibles and maxillae: sheathed within a modified labium to form a proboscis

• Some hemipterans have a modified gut

  • Filter chamber: separates excess fluid from plant sap rapid erection (-> honeydew)

• Key Agricultural Insect Pest

Order Hemiptera: Suborder Auchenorrhyncha: Family Cicadellidae

• Leafhoppers and sharpshooters

  • Feeding, disease transmission

  • Excessive honeydew production

• Filter chamber: separates excess fluid from plant sap rapid erection (-> honeydew)

• Key Agricultural Insect Pest

Why are trees are difficult for insect herbivores to access?

• Trees are filled with carbon, but this form of carbon is challenging for animals-> animals cannot breakdown cellulose on their own during digestion-> gut microbes

Symbiosis

• close, long term interaction between species, ranges from mutual to harmful

• how insects formed symbiotic partnerships to feed on trees

Key Pests of Trees: Orders

• Order Blattodea

• Order Coleoptera

• Order Lepidoptera

Order Blattodea: Suborder Isoptera

• “termites”

• Feed on living and dead trees (leaves, twigs, wood, lumber, feces)

• Able to digest cellulose (microbial gut symbionts OR farmed fungi)

• 2 pairs of similarly sized wings-> Reproductives only

• Social colonies: reproductives (king & queen), workers, soldiers

• Key Pests of Trees

Order Coleoptera: Family Buprestidae

• Metallic wood boring beetles

  • Structural coloration

  • Elytra sometimes used in jewelry

  • Larvae bore into wood (usually dead or dying) or mine leaves

• Emerald Ash Borer (EAB)

  • Feed on ash trees, disrupting nutrient and water flow

  • Invasive pest

• Key Pest of Trees

Order Coleoptera: Family Cermbycidae

• Long-horned beetles

  • Larvae of some species bore into wood

• Asian long-horned beetle

  • Kills maples, birch, poplar, willows, and elms

  • Destroy up to ~30% of urban trees

• Key Pest of Trees

Order Coleoptera: Family Scolytidae

• Ambrosia beetles

  • Beetle drills into the tree, fungus infects the tree, and the beetle produces offspring in the tree

• Mycangia

• Key Pest of Trees

Order Coleoptera: Family Curculionidae

• Mountain pine beetles (weevils)

  • Outbreak in Rocky Mountain National Park has destroyed millions of acres of ponderosa and lodgepole pine trees

  • Fungus blocks water and nutrient transport in trees

  • More pesty due to global warming-> warmer weather, more thriving

• Key Pest of Trees

• South American palm weevil

  • Recently invaded SoCal

  • Canary Islands date palm and edible date palms most threatened ($140 million industry in SoCal

• Key Invasive Insect Pest

Order Lepidoptera: Family Erebidae

• Spongy moth

  • Generalist larvae feed on over 500 species of hardwood trees (leaves of birch, ash, oak)

  • Heavily defoliate trees

• Key Pest of Trees