Post on 18-Dec-2015
transcript
Ecdysozoans
Planktonic cyclopoid copepod (Cyclops strenuus). LM. Copyright Robert Brons/BPS.
red-kneed tarantula; Mexico. Copyright Barbara J. Miller/BPS.adult polyphemus moth
(Antheraea polyphemus). Copyright Peter J. Bryant/BPS.
Green Darner dragonfly has just emerged from its larval exoskeleton and is pumping fluids into its expanding wings.
Monophyly of Ecdysozoa supported by molecular and genetic evidience,including a common set of homeobox genes
Cuticle and molting arose in the common ancestor to this clade
Discussion will focus on adaptive significance of the various exoskeletons in this lineage,and of the ability to shed that exoskeleton
Ecdysozoa includes a dozen or more phyla; we will concentrate on two: Arthropoda primarily, and Nematoda to some extent.
Family Culicidae: mosquito (Culex sp.), engorged with blood. Copyright Robert Brons/BPS.
NematodaRoundworms
Pinworms
Filarial heart worm Filarial Worms
Trichinella
Trichinella, a parasitic roundworm that infects mammals
-thick, multi-layered cuticle secreted, related to characteristic locomotion
-exchange oxygen and nutrients with environment through both cuticle and complete gut (two openings - mouth and anus)
-free-living and parasitic forms
-among the most abundant and universally distributed organisms -- tremendous ecological importance
Structure of a nematode as illustrated by Ascaris female
Source: Raven et al (2002)
The tremendous success -- diversification, adaptive radiations-- of Arthropods is related to:
Fundamental design features in their body plan-rigid exoskeleton -segmentation -jointed appendages
Specialization of groups of body segments and appendages for many different functions
Head
Thorax
Abdomen
Flexor muscleExtensor muscle
Joint between leg segments
Exoskeletonjointed limbs
Chelicerates Trilobites Insects Crustaceans
Above; the four main lineages of arthropods
Right; important features of arthopod body plan
Sources: Freeman (2002), Campbell (2002)
About 2/3 of all described species are arthopods; about half of those arthropods are insects; about half of those insects are beetles
Phylum Uniramia (= “one branch”)
-Myriapods (below). ~20,000 species in four groups, including centipedes and millipedes, with relatively undifferentiated segments and appendages
-Insecta (right)~1.5 million described species (small fraction of actual diversity)
Apterygotes insects lacking wings
Pterygotes winged insects; includes lineages that lack metamorphosis, undergo incomplete metamorphosis, or undergo complete metamorphosis
John Meyer UNC http://www.cals.ncsu.edu/course/ent425/tutorial/integ.html
Several differentiated layers of cuticle
Epidermis and underlying basement membrane
Exocrine Gland
Setae PileJoint Skeletal muscles
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Keaton & Gould 1993
Flight is a key adaptation that contributed to the adaptive radiation of insects
Direct flight muscles (attached to wings) are responsible for downstroke and indirect flight muscles for upstroke in grasshoppers
Grasshopper launching into flight
Expressed segmentation genes in fruit flies. Antibody staining shows the location of segmentation gene products in fly embryos
Genes in the homeotic complex encode regulatory proteins that affect embryonic pattern formation
Insect Onychophoran Segmented worm Crustacean
Distal-less expression in protostomes. These embryos have been stained with an antibody to theproteing produced by Dll. In each case, the Dll gene product is localizd in cells that will become part of an outgrowth from the body, such as a limb
Arthropods have open circulatory systems
hemolymph is pumped by one or more hearts through arteries and into sinuses (pockets) surrounding tissues and organs. Hemolymph reenters the circulatory vessels through pores
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Cuticle
Valve
Commissural tracheae
Ventral trachea
Dorsal trachea
Spiracles
Tracheoles
Various mechanisms of gas exchange have evolved in Arthropods
-Gas exchange in terrestrial arthropods typically occurs in specialized internal surfaces
Gas exchange in aquatic arthopods typcially occurs across gill surfaces
Raven (2002)
A group of spawning horseshoe crabs
Keaton & Gould (1993)
Book Gills
Source: Campbell (2002)
Molting and Metamorphosis
Molt; Periodic shedding and replacement of exoskeleton to allow growth
Metamorphosis; change from juvenile to adult body form;
Both processes are controlled by the interaction of two neurosecretory hormones: ecdysone and juvenile hormone
Hatching
Molt
Molt
Molt
Molt
Metamorphosis
Hatching
Molt
Molt
Pupation
Pupation
Pupa
Adult
Larvae
Juveniles
All insects metamorphose. Some lineages undergo partial metamorphosis, and some complete metamorphosis
Molt and Metamorphosis are regulated by neurosecretory hormones; juvenile hormone and ecdysone
Pulse of Ecdysone when JH is high causes molting
Pulse of Ecdysone when JH is low causes metamorphosis
Source: Freeman (2002), Hickman et al (2001)
Sgs-3
Lsp-1a
IMP-E1 Genes
FTZ-F1
Usp
Changes in gene expression during insect metamorphosis are caused by ecdysone
Source: Freeman (2002)
Crustaceans
Uniramians Remipedia Cephalocarida Branchiopoda Maxillopoda Malacostraca
Chelicerates
Extra slides
L320652Family Theraphosidae: red-kneed tarantula; Mexico. Copyright Barbara J. Miller/BPS.
L320653Family Lycosidae: a wolf spider (Lycosa sp.). Copyright Peter J. Bryant/BPS.
L320654Family Thomisidae: female crab spider (Misumenoides formocipes), on lantana blossom. Copyright Peter J. Bryant/BPS.
L320655Family Oxyopidae: female green lynx spider (Peucetia viridans), with fresh egg case. Copyright Peter J. Bryant/BPS.
L320656An immature daddy long-legs (Leiobunum sp.). Copyright BPS.
L320657An adult pseudoscorpion (species unknown). Copyright Peter J. Bryant/BPS.
L320658A wood tick (Ixodes ricinus), piercing human skin. Copyright Robert Brons/BPS.
L320659Wind scorpion (Eremobates sp.). Copyright BPS.
L320660Adult brine shrimp (Artemia salina). Copyright David J. Wrobel/BPS.
L320661Tadpole shrimp (Triops sp.). Copyright David J. Wrobel/BPS.
L320662Water flea (Daphnia sp.), with embryos. Copyright Peter J. Bryant/BPS.
L320663Calanoid copepod group (Calanus sp.); Monterey Bay, CA. Copyright David J. Wrobel/BPS.
L320664Planktonic cyclopoid copepod (Cyclops strenuus). LM. Copyright Robert Brons/BPS.
Flatworms (Platyhelminthes)Simple Lophtrochozoans
-bilateral symmetry
-cephalization
-lack organs for oxygen transport
-simple organs for excreting metabolic waste
-gut with single exterior opening
-relationship between oxygen transport, waste elimination and flat, high surface area to volume ratio, body plan
-free-living and parasitic forms
AnnelidaSegmented worms
Polychaeta Oligochaeata Acanthobdellida Branchiobdellida Hirudinea
Feather duster - marine annelid
Earthworms - Oligochaetes
Australian Tiger LeechPolychaetes living around thermal vent
-radiations in terrestrial, freshwater and marine habitats
-segmentation;septa dividing coelomiccavity alters function of hydrostatic skeleton
-most lack rigid, external body covering; gas exchange occurs across body wall in most spp.
Mollusca
Monoplacophorans
Gastropods
Cephalopods
Bivalves
Scaphopods
Polyplacophorans
-extensive adaptive radiations related to variations on body plan based on foot, mantle, and visceral mass
Chitons
Snail
Giant Clam Slug
Octopus
Nautilus