Biology 3: Deuterostomes (sbm9 Ch 32)




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Biology 3: Deuterostomes (SBM9 Ch 32) ©2011 copyright Marta D. de Jesus
VII. Deuterostomes in general

A. Remember the development process defines the group

B. at the base of this group {news this year (2/11)}

xenoturbellids & acoelomorphs

C. P: Echinodermata

1. general characteristics

a.

b.


c.

d.


2. classes (T32-1)

a. C: Crinoidea


b. C: Asteroidea
c. C: Ophiuroidea
d. C: Echinoidea
e. C: Holothuroidea

D. P: Hemichordata

E. P: Chordata

1. general

a.

b.


c. 4 specific characteristics

1)
2)


3)
4)
2. SP: Urochordata

3. SP: Cephalochordata


D. Craniates



Haikouella
E. SP: Vertebrata

1. in general

a.
b.
c.
d.
e.
2. early vertebrates

a. Haikouichthys


b. conodonts
c. ostracoderms
3. modern agnathans

a. C: Myxini


b. C: Petromyzontidae (Cephalaspidomorphi)

4. gnathostomes
a. changes

1)
2)


3)
4)
b. early extinct members

1) placoderms

2) acanthodians

5. C: Chondrichthyes

placoid scales

reproduction

1) some are oviparous

2) many are ovoviviparous

3) a few are viviparous
6. clade Osteichthyes

a.
b. operculum


c.
d.
e.
f.
7. C: Actinopterygii

8. clade Sarcopterygii


a. C: Actinistia
b. C: Dipnoi
9. clade Tetrapoda

a. ancient examples

1) Tiktaalik
2) Acanthostega
b. C: Amphibia

Ichthyostega

O: Urodela

O: Anura

O: Apoda


10. clade Amniotes

a. amniotic egg


1) allantois

2) amnion


3) chorion
4) yolk sac

split into

1) clade Diapsida

2) led to


ectothermic


endothermic
poikilothermic
homeothermic
split between

(i) “anapsids” -> O: Testudines - turtles & tortoises

(ii) all other reptiles (don’t need to learn extinct groups)

clade Lepidosauria

O: Squamata

O? Testudines (7/11)

O: Sphenodonta

clade Archosauria

O: Crocodilia:

O: Birds


(iii) what are birds?

MicroRNAs support a turtle + lizard clade

Published online before print July 20, 2011, doi: 10.1098/rsbl.2011.0477

http://rsbl.royalsocietypublishing.org/content/early/2011/07/08/rsbl.2011.0477

Tyler R. Lyson, Erik A. Sperling, Alysha M. Heimberg, Jacques A. Gauthier, Benjamin L. King and Kevin J. Peterson


Abstract

Despite much interest in amniote systematics, the origin of turtles remains elusive. Traditional morphological phylogenetic analyses place turtles outside Diapsida—amniotes whose ancestor had two fenestrae in the temporal region of the skull (among the living forms the tuatara, lizards, birds and crocodilians)—and allied with some unfenestrate-skulled (anapsid) taxa. Nonetheless, some morphological analyses place turtles within Diapsida, allied with Lepidosauria (tuatara and lizards). Most molecular studies agree that turtles are diapsids, but rather than allying them with lepidosaurs, instead place turtles near or within Archosauria (crocodilians and birds). Thus, three basic phylogenetic positions for turtles with respect to extant Diapsida are currently debated: (i) sister to Diapsida, (ii) sister to Lepidosauria, or (iii) sister to, or within, Archosauria. Interestingly, although these three alternatives are consistent with a single unrooted four-taxon tree for extant reptiles, they differ with respect to the position of the root. Here, we apply a novel molecular dataset, the presence versus absence of specific microRNAs, to the problem of the phylogenetic position of turtles and the root of the reptilian tree, and find that this dataset unambiguously supports a turtle + lepidosaur group. We find that turtles and lizards share four unique miRNA gene families that are not found in any other organisms' genome or small RNA library, and no miRNAs are found in all diapsids but not turtles, or in turtles and archosaurs but not in lizards. The concordance between our result and some morphological analyses suggests that there have been numerous morphological convergences and reversals in reptile phylogeny, including the loss of temporal fenestrae.


3) clade Synapsida

clade Therapsida ->

a. all have:

b. Protherians


c. Metatherians

d. Eutherians



e. cases of convergent evolution


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