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Immutable
Unchanging over time; unable to be changed
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Homology
When different species have the same structures or genes because of a shared ancestor
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Define clade.
All organisms within a single evolutionary lineage; stemming from a common ancestor (can also be called taxon)
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Define ancestral (primitive)
Appearing earlier in the fossil record, ancestral character state
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Define derived.
Appearing later in the fossil record as a new evolutionary innovation, descendent character state
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Define analogous structures.
Organs or structures having similar functions but not sharing an ancestor
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Describe a heterocercal caudal fin.
- A tail fin with unequal lobes in which the vertebral column turns upward into the larger lobe as in sharks
- Provides lift while swimming, counteracting the tendency to sink
- They need these fins because they lack a swim bladder
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Describe a homocercal caudal fin.
- Symmetrical tail fin extending beyond the end of the vertebral column as in most bony fishes
- These fish have swim bladders for buoyancy so they do not need the heterocercal tails
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Biological species concept
A group of similar-looking individuals capable of successfully interbreeding
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Phylogenetic species concept
A genetically distinct group reproductively isolated from other such groups (i.e., gene flow restricted)
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Classification System (general to specific)
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
- Did King Philip Come Over For Good Spaghetti
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Describe the taxonomic unit system.
- Each successful higher unit contains fewer and fewer shared traits
- The higher the taxonomic unit the less closely related the animals in that group are
- Class has fewer shared characteristics than family
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Describe Deuterostomes
- The blastopore (an opening occurring in early embryo) becomes the anus. (Anus first mouth second)
- Includes echinoderms, hemichordates, and chordates
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Describe protostomes.
- Blastoprore (an opening occurring in early embryo) becomes mouth. (Mouth first, anus second)
- Includes Molluscs, Annelids and arthropods
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Blastopore
An opening occurring early in embryo
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Phylum Chordata
Vertebrates and Invertebrate chordates
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Four chordate morphological characteristics
- Notochord - stiff supporting rod along dorsal part of body, under dorsal nerve cord
- Pharyngeal gill slits - more efficient food intake
- Dorsal hollow nerve cord
- Post-anal tail
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Why is thyroxine so important to chordates?
- Adequate growth
- Development
- Tissue Differentiation
- Metabolic rate
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What do all chordates have that produce thyroid hormones.
- They all have cells that produce these. Endostyle or thyroid gland
- Endostyle = glandular groove in floor of pharynx; involved in filter feeding
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What is an endostyle?
A glandular groove in floor of pharynx; involved in filter feeding
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In vertebrates, what is a major importance of thyroxine?
Proper brain development and for reproduction
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Georges Cuvier
- Saw species as immutable
- Used evidence from fossils
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Richard Owen
- Saw species as immutable
- How to explain corresponding body parts e.g., homologous structures
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Darwin and Wallace
- Species are not fixed
- Present characters must be derived from already existing structures
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Pterobranchs
- Tiny, rare marine animals that form plant-like colonies; individuals project like small "flowers" at the end of a secreted tube
- Possess one pharyngeal gill slit, but no other chordate characteristics
- Filter feed by ciliary action
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Related Phylum - Hemichordata
- Pterobranchs (class pterobranchia)
- Acorn worms (class enteropneusta)
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Acorn Worms
- Elongated worm-like animals that burrow in tidal mud flats
- Anterior end with a probosics (used in burrowing) followed by a collar (contains mouth) - these structures also found in pterobranchs
- Well developed pharyngeal slits
- Dorsal nerve cord (not complete)
- Stomocord - stout pouch of support tissue
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Hox Genes
- Genes involved in early development
- Produce reversed dorsal and ventral body pattern between chordates and all other animals, including hemichordates
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Phylum chordata consists of 3 subphyla
- Urochordata (tunicates or sea squirts)
- Cephalochordata (lancelets - amphioxus)
- Vertebrata (vertebrates or craniata - hagfish + vertebrates)
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Urochordates (tunicates)
- Marine animals that may be solitary or colonial
- Adults have sac-like shape with outer covering a "leathery" tunic (cellulose)
- Filter feeders using pharyngeal gill slits
- Larvae are free swimming and have all 4 chordate characteristics
- Larvae metamorphose into sessile adults - notochord, dorsal nerve cord and post-anal tail degenerate
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Cephalochordates (amphioxus)
- Elongated, vaguely fish-like marine animals that live mainly buried in sand or silt with the head region protruding
- Are capable of swimming
- Possess all 4 chordate characteristics as adults
- Filter feeders using pharyngeal gill slits
- No paired fins present only metapleural folds
- Possess segmentally arranged muscle masses (myomeres)
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Vertebrata (vertebrates)
- Characterized by cephalization
- This necessary because vertebrates are active animals and need to perceive info from front of body
- Possess vertebral column (backbone)
- Specialized kidney tubules
- Fish, amphibians, reptiles, birds, mammals
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