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