Lecture 1/2: Vertebrate Evolution

why is evolution central to vert. biology?

because it provides a principle that organizes the diversity we see among extant vert

describe the proportion of Metazoan diversity?

inverts > plants > fungi > unicellular protists > verts

why do we care about verts?

bc we are verts, conspicuous (big/complex), charismatic

describe the proportion of marine vert phylogeny?

fish/sharks/lungfish (1/2 of all verts) > reptiles > amphibians > mammals

• describe the behaviors of the 65,000+ extant vert species.

• what is the weight range?

• where do they live?

• composed of a full spectrum of diverse and complex behaviors (eating, reproduction, metabolic)

• 0.1g - 100,000 kg

• live in ALL of Earth’s habitats

• for each extant sp, there may be 100’s of extinct species

what are the 3 main differences between non-amniotes and amniotes:

• where do they live?

• describe what produces the embryos and membranes

• what organisms are these found in?

• non-amniotes

  • aquatic

  • embryos enclosed and protected by membranes that are produced by the female reproductive tract

  • seen in inverts and retained in fishes and amphibians

• amniotes

  • terrestrial (well established on land by the Permian/300mya)

  • fetal membranes are derived from the embryo itself

  • seen in secondarily aquatic animals which used to live on land but are back in the water (i.e., sea turtles, whales, salamanders, frogs)

what are the 4 groups of non-amniotes?

jawless fishes, Chondrichthyes, Osteichthyes, and Lissamphibia

what 2 types of organisms make up the jawless fish group and where do each live? what are the 5 traits of the jawless fish group?

• hagfishes are marine

• lampreys are anadromous (spawn freshwater)

• limbless, scaleless, jawless, slimy, no internal bony structure

what 3 types of organisms make up Chondrichthyes? what is the overall characteristic?

• sharks, rays, and ratfish/chimaeras

• cartilaginous skeletons

what is the organism that makes up Osteichthyes?

bony fish

what is the organism that makes up Lissamphibia?

modern amphibians (i.e., salamanders, frog, caecilians)

what 2 groups of organisms are in amniotes?

• sauropsids = reptiles including birds

• synapsids = mammals

what is the order of evolved verts?

jawed verts (cartilaginous fishes) => bony fishes => ray fined fishes (non-teleost ray-finned fishes and teleosts) => lobe-finned fishes (coelacanth => african lungfish) => first vert landing (tetrapods)

what are the 4 groups of organisms in the Sauropsid Amniotes group? provide trait for each

• Testudinia = turtles

  • shelled

• Lepidosauria (tuatara, lizards, snakes)

  • scaled skin

• Crocodilia (alligators, crocs)

  • bony skin, parental care

• Aves = birds

  • feathers = derived from ornamental feathers of dinos for courtship

what is the major group of Synapsid Amniotes and its trait?

Mammalia; lactation

what are the three groups of Mammalia

• Monotremes = egg laying mammals

• Marsupials

• Placentals

what trait do placentals and marsupials have?

both placentals and marsupials have a placenta that transfers nutrients and removes waste

define systematics

evolutionary classification of organisms

why does systematics matter?

to better understand diversity (i.e., who is related to who, evolution), biomed purposes (i.e., testing drugs on related animals to humans)

define bionomical nomenclature

genus species name in universal Latin language

what is the importance of scientific names over common names?

allows universal communication no matter where you are in the world, common names are confusing and inaccurate (i.e., crawdad, little lobster, crayfish)

define taxa

species are arranged in hierarchical categories

define phylogenetic systematics

method of determining evolutionary relationships in which groups of organisms are linked by a nested series of characters that trace the evolutionary history of the lineage

define phylogeny

diagram showing sequences of branching during evolution => it’s a hypothesis

define apomorphy

derived character, away from the ancestral condition that cannot distinguish between lineages

define synapomorphy

shared derived characters used to build phylogeny

define plesiomorphies

ancestral characters, inherited unchanged from ancestors

How do scientists know which character state is ancestral (plesiomorphic) and which is derived (apomorphic)? How can we determine the direction of evolutionary transformation of characters?

additional info is needed

define outgroup

reference group that is less closely related to any member of the ingroup

how has the creating of phylogenies evolved over time?

originally, anatomical traits were used as characters. today, molecular biology and genetics and computers. best is the combo of molecular and morphological data

what is included in tree nomenclature?

root, branch, node, branch length, clade

what are phylogenetic trees used for?

• to ask questions about evolution

• make inferences about the biology of species