test 1 Flashcards
study of structure and function and how that structure plays a role in evolution of new forms
morphology
suggest descent from a common ancestor, inherited similarities, relates to origin
homologous structures
solutions to a common challenge, relates to function; similar function in similar habitats can produce convergent forms; lead to convergent evolution
analogous structures
any similarity between characters that is due to their shared ancestry, common historical ancestry can carry forward shared structures
homology
occurs when characters are similar, but are not derived from a common ancestor; accidents and incidental events can make parts look alike
homoplasy
a structure or behavior possesses the necessary form and function before the biological role arises that it eventually serves, adaptive traits serve the roles of the moment if there is not an immediate role selections eliminates the trait, traits do not anticipate a later need or role
preadaptation (exaptation)
homologous characters that already exist in a common ancestor
primitive condition/plesiomorphic trait
homologous characters that have evolved more recently and therefore only occur among certain species in the cladogram
derived condition/synaptomorphic trait
a group of organisms that is given a name
taxon
a group of organisms that exists as a result of evolutionary process: a species is a lineage, a collection of organisms that share a unique evolutionary history and are held together by the cohesive forces of reproduction; a monophyletic group or clade is a group of taxa encompassing an ancestral species and all its descendents
natural taxon
represents an incomplete or invalid evolutionary unit: paraphyletic group and polyphyletic group
artificial taxon
a taxon that includes an ancestor but not all of the descendants of that ancestor
paraphyletic group
artificial because its members are derived from 2 or more ancestral forms not common to all members
polyphyletic group
clade of animals characterized by the formation of the organism’s mouth before its anus during embryonic development; blastopore (mouth), spiral cleavage, schizocoelic coelom, ectodermal skeleton
protostome
animals characterized by their anus forming before their mouth during embryonic development; blastopore (anus), radial cleavage, enterocoelic coelom, mesodermal skeleton
deuterostome
notochord, pharyngeal slits, endostyle/thyroid gland, dorsal hollow nerve cord, postanal tail
what cephalo- and urochordates and vertebrates have in comon
cephalo- and urochordates: lack a bony or cartilaginous skeleton, all marine, suspension feeders; vertebrates: possess endoskeleton, terrestrial or marine, most use jaws to feed
differences between cephalo- and urochordates and vertebrates
notochord, pharyngeal slits, endostyle/thyroid gland, dorsal hollow nerve cord, postanal tail
5 fundamental features of chordates
develops from mesoderm, ventral to nerve cord, mechanical properties of a rod but biomechanically a hydrostatic skeleton
notochord
all chordates have had these, functions: suspension feeding-via mucus, respiratory exchange; evolution of a muscular pharyngeal pump, superior fluid movement compared to cilia
pharyngeal slits
derived from ectoderm in embryonic origin, formed through invagination of a neural plate, sinks to reside dorsally from notochord
dorsal hollow nerve cord
share some or all 5 features of the fundamental chordate body plan; larval-pelagic/planktonic (limited locomotor capability), metamorphosis, adult-benthic/burrowing/sessile; marine animals that feed by means of cilia and mucus
protochordates
first appearance of chordate body plan components, sister taxa with echinoderms, features=pharyngeal slits, dorsal collar cord, epibranchial ridge; burrow or suspension feeders: cilia and mucus food capture, in mouth to pharynx out pharyngeal slits to brachial pouch and out brachial pores; show traits that link chordates and echinoderms
hemichordates
primarily water exit during filter feeding, secondarily respiratory exchange through vascularized tongue bar, branches from the dorsal and ventral blood vessels supply each tongue bar suggesting that respiratory exchange also occurs in the pharyngeal slits of the hemichordate
function of the pharyngeal slits
deuterostome; ciliated, simple gut, planktonic larva: resembles the auricularia larva of echinoderms, molecular and morphological agreement therefore single taxa; some species of hemichordata whose larval metamorphosis results in a circulatory and excretory system with probable vertebrate homology
tornaria larva
muscular contractions cause contraction of notochord muscle cells via the nerve cord resulting in stiffening, possible for burrowing or bursts of speed
unique amphioxus notochord
only the larva exhibits all 5 chordate features
urochordate ascidian larva
nervous system: sensory vesicles (ocellus/otolith), cerebral ganglion, visceral ganglia, dorsal hollow nerve cord
amphioxus cephalochordate
vertebral column: defines the body axis, incrementally replaced the notochord to meet the mechanical demands of the organism; head: defined by cranium/skull, cephalization clustered sensory organs (the enlarged anterior part of the neural tube), vertebrate sensory organs of the head are derived from vertebrate-unique neural crest cells and epidermal placodes (unique neurogenic ectoderm)
vertebrate innovation
mechanical changes to the pharynx: encircling bands of muscle, cartilage replaced collagen in pharyngeal bars, muscular pump incrementally replaced cilliary pumps, removed overall organisms size limits, drove gill evolution to satisfy respiratory demands; muscular suspension feeding and respiration currents: increasingly active lifestyle and cephalization; raptorial feeding: selective feeding/forceful capture of larger particles, expansion and closure of the pharyngeal pump, anterior pharyngeal bars become grasping jaws, active predation of large prey
evolutionary features of gnathostome (jawed vertebrates)
five common chordate features, cephalized brain and vertebrae, dermal skeleton and lateral line, pectoral fins, jaws and pelvic fins
early fish evolution synapomorphies
early vertebrate lacking jaws with a biting apparatus derived from pharyngeal bars (muscular pump to produce food-bearing water current), larval benthic, suspension feeder, showing much similarity to amphioxus
agnathans
product of the cambrian explosion; amphioxus-like pharynx, atrium, and atriopore; lacked skull and ear capsule, straight myomers; vertebrate-like gill filaments large brain with putative eyes and vertebrae; agnathan chordate
haikouella
skull elements with sensory organs, gill bars, v-shaped myomeres, heart; agnathan vertebrate
haikouichthys
mysterious mineralized fossil teeth finally connected to a jawless but very motile vertebrate, modification on pharyngeal basket suspension feeding into moving plates that caught and shredded food, recent analysis had shown evidence of convergent tooth evolution; extinct group of agnathan (jawless) vertebrates
conodonts
“shell-skins”, agnathan, complex eyes, dentin: neural crest derived tooth component, few appendages, sensory lateral line, evolution of bone: dermal bone body armor covering cartilage vertebral skeleton
ostracoderms
“fleshy-finned fish”-pivoting in shallow water (lungfish) or holding on to bottom (coelacanths); gave rise to tetrapods via rhidipstians: cosmoid scale, no link between skull and pectoral girdle, robust pectoral digit bones, flattened skull with dorsal spiracle for air breathing, loss of bony gill covers, large ribs for torso support on land
sarcopterygii