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three major methods for tree construction:. 1. parsimony - the tree with the least total transitional steps is the best tree 2. maximum likelihood - calculated probabilities of producing a particular character set given assumptions concerning

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three major methods for tree construction:

1. parsimony - the tree with the least total transitional

steps is the best tree

2. maximum likelihood - calculated probabilities of producing

a particular character set given assumptions concerning

state change probabilities and given certain tree topologies

with known branch lengths. the best tree is the one that

has the highest probability.

3. distance matrix - this is not unlike what many of you

probably did naturally in the lab to draw your trees from

the data on primate evolution. data is converted into

"distance values" and the best tree is the one that minimizes

the total distance among all of the taxa.

Why are trees useful?

Andrew Siefert

life cycle

of the fig

(Ficus) and

the fig wasp

active pollination

passive pollination

mixed

Cook, J. M., Bean, D., Power, S. A. & Dixon, D. J.

Evolution of a complex coevolved trait: active pollination in a genus of fig wasps.

Journal of Evolutionary Biology  17 (2), 238-246.

Figure 4. Major stages in the evolution of modern avian skeletal design and function. Many skeletal innovations of critical functional importance for flight arose for other purposes among early theropods, including (1) the hollowing of all long bones of the skeleton (Theropoda) and removal of pedal digit I from its role in weight support; (2) evolution of a rotary wrist joint to efficiently deploy a large grasping manus; (3) expansion of the coracoid and sternum for increased pectoral musculature and plumulaceous feathers for insulation (89); (4) the presence of vaned feathers arranged as primaries, secondaries, and rectrices for display or brooding or both; (5) shortening of the trunk and increased stiffness of the distal tail for balance and maneuverability. Archaeopteryx remains a pivotal taxon, documenting (6) the acquisition of basic flight and perching function before the close of the Jurassic (laterally facing shoulder joint, split propulsion-lift wing with asymmetric feathers, and reversed hallux). Key refinements of powered flight and perching in later birds include (7) the deep thorax with strut-shaped coracoid and pygostyle; (8) the triosseal canal for the tendon of the principal wing rotator (the supracoracoideus muscle), alular feathers for control of airflow at slow speeds, rectriceal fan for maneuverability and braking during landing, and fully opposable hallux for advanced perching; and (9) the elastic furcula and deep sternal keel for massive aerobic pectoral musculature (90).

Paul C. Sereno. 1999. The Evolution of Dinosaurs. Science284: 2137-2147

(C) Polar dispersal across Beringia (double-headed arrow) must be invoked to explain the geographic distribution of ceratopsians and other dinosaurian subgroups during the Late Cretaceous. Checkered branches show dispers- al from Asia to North America in three lineages, which is one of two equally parsimonious dispersal scenarios for ceratopsians (given this cladogram and an Asian origin for Ceratopsia). Globe shows Maastrichtian (70 Ma) paleogeography divided into orogenic belts (inverted Vs), lowlands (black), and shallow and deep seas (gray and white, respectively). Internal branch lengths of the cladogram are scaled according to the number of supporting synapomorphies under delayed character-state transformation. Scale bar indicates 10 synapomorphies (with the long ceratopsid branch shortened).

Paul C. Sereno. 1999. The Evolution of Dinosaurs. Science284: 2137-2147

Feeding and nonfeeding larvae

Feeding larva

Egg

Juvenile

Egg

Nonfeeding larvae

Juvenile

PLANKTOTROPHS…

need to feed in order to reach metamorphosis

LECITHOTROPHS…

can reach metamorphosis in the absence of food

So which is ancestral, planktotrophy or lecithotrophy??

…for each of the five echinoderm classes?

…for echinoderms as a whole?

sea cucumbers

(holothuroids)

(phylogeny a la

Kerr & Kim 2001)

developmental mode

unordered

planktotroph

lecithotroph

both

equivocal

brittle stars & basket stars

(ophiuroids)

(phylogeny a la

Smith et al 1995)

developmental mode

unordered

planktotroph

lecithotroph

both

equivocal

sea stars

(asteroids)

(phylogeny a la

Blake 1987)

developmental mode

unordered

planktotroph

lecithotroph

both

equivocal

sea urchins and sand dollars

(echinoids)

(phylogeny a la

Littlewood & Smith 1995)

pencil urchins

(cidaroids)

(phylogeny a la

Smith & Wright 1988)

pencil urchins

(cidaroids)

(phylogeny a la

Smith & Wright 1988)

one half of the

deuterostomes

(phylogeny a la

Littlewood et al. 1997)

…and their

different larvae

(phylogeny a la

Littlewood et al. 1997)