Systematics of Eutherian Mammals and Scandentia

A. Phylogenetics

Phylogeny: hypothesis about evolutionary relationships between organisms
Principle of Parsimony: simplicity! inheritance from common ancestor
Synapomorphies: shared, derived traits define monophyletic groups (basis of cladistics)

B. Why are phylogenies important?

Biodiversity (Tree of Life)

Evolution (e.g. primate social organization)

Biomedical research

Conservation biology

Agriculture

C. Controversies

Origin of Placental Mammals (170 MYA?); SuperOrders?
Rise of Modern Orders 65 or 100 MYA?
Gaps / Biases in Fossil Record (‘Garden of Eden’ hypothesis)
Two Types of Data

Morphology

Molecular Genetics

Morphology	Molecules
Later, sudden radiation (K-T boundary, 65 MYA)	Early divergence(~100 MYA; neutral theory, mol.dating)
Supported by fossil record	But where are the fossils?
Convergence?	Robustness of analyses?

D. George Gaylord Simpson

1945 – ‘Principles of Classification and a Classification of Mammals’
Major SuperOrders (~65 MY old)

GLIRES: Rodents & Lagomorphs
UNGUICULATA: bats, primates, treeshrews, colugos, insectivores, xenarthra
FERUNGULATA: elephants, sirenians, hyraxes, perissodactyls, artiodactyls, carnivores, aardvark

E. Later SuperOrders (~65 MY old)

UNGULATA: Cetartiodactyla, Paenungulata, Perissodactyla
FERAE: Carnivores, Pholidota
ARCHONTA: bats, primates, treeshrews, and colugos
GLIRES: rodents, lagomorphs
LIPOTYPHLA: Insectivores
XENARTHRA

F. Recent Advances

New Fossils (China)
Supertrees
Molecular data
Analytical techniques

Maximum parsimony
Maximum likelihood
Bayesian inference

G. Fossils

Eomaia scansoria
Early true eutherians show locomotor diversity (terrestrial, scansorial)
70-125 MY old
99% of all mammal species that have existed are now extinct

H. Supertrees

Combines topologies of trees (phylogenies) from all known studies
Uses ALL Data
Computationally intensive
Primates, Carnivores, Chiroptera complete

Supertree: 430 trees, 315 studies

I. Ascendancy of Molecular Data

Molecular supertree > Morphological supertree
AFROTHERIA: Hyracoidea, Proboscidae, Sirenia, Tubulidentata, Macroscelidae (4 places previously)
Problems: still many conflicts and weakly resolved relationships
Large Molecular Phylogenies needed

J. Molecular Tree
16,400 bp, 19 nuclear genes, 3 mtDNA genes, all major lineages

K. New Synthesis

Afrotheria 103 MY
Xenarthra 95 MY
Boreoeutheria (Euarchontoglires & Laurasiatheria) 79-88 MY
Insectivores?
Fossils?

L. Euarchontoglires (controversy cont.)

Rodents, lagomorphs, treeshrews, dermopterans, primates
Who is sister taxon of primates?
Primates paraphyletic?
Mitogenome tree

Dermoptera sister to Anthropoidea?
mtDNA of dermoptera more similar to Anthropoids than tarsiers and prosimians?
Probably Not
mtDNA signal misleading: tarsiers, strepsirhines à directional mutational pressure
All primates share transposable elements not found in dermopterans

M. What is a treeshrew?

Mammal; Order Scandentia, Family Tupaiidae (16-19 spp.)
NOT Shrews or Squirrels
Most spp. active on ground; diurnal, scansorial
Insectivorous, Frugivorous
Socially monogamous
Restricted to SE Asia; many spp. endemic to Borneo

N. Taxonomic History

1780, William Ellis, squirrel
Pre-1900, Insectivora (wastebasket)
Primate (anatomy, 1000 biomedical citations)
1980, Scandentia
Future? (genomics, morphology)

O. Introduction

SE Asian Rainforest: biodiversity and timber production
Selective Logging on Borneo

3-7% trees removed, destruction up to 50% = habitat matrix
Species not eliminated, but abundances and behavior altered
Biologically-important habitat

P. Objectives of J. South's Study

Territoriality, mating patterns, and dispersal of Large Treeshrew (Tupaia tana) in primary forest
Behavioral responses to logging
Experimental manipulations of resource abundance:
Is variation in food abundance responsible for behavioral changes?

Q. Study Site

Danum Valley Field Centre, Northeast Borneo, Sabah, Malaysia
438 sq km; largest fragment of lowland dipterocarp rainforest in Borneo
Junction of primary and logged areas

R. Citations (all are available online through UMD; need Adobe Acrobat reader to view them)

Arnason, U., et al. 2002. Mammalian mitogenomic relationships and the root of the eutherian tree. Proceedings of the National Academy of Sciences 99(12): 8151-8156.

Liu, R. F., et al. 2001. Molecular and morphological supertrees for eutherian (placental) mammals. Science 291: 1786-1789.

Murphy, W. J., et al. 2001. Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science 294: 2348-2351.

Schmitz, J., et al. 2002. The Colugo (Cynocephalus variegatus, Dermoptera): the primates' gliding sister? Molecular Biology and Evolution 19(12): 2308-2312.