Understanding Systematics: Describing Species Relationships

1. Chapter 3 - Systematics Friday we’ll have lab after class

2. Systematics • Describing the relationships of extinct and extant species • Physical characteristics, molecular similarities, DNA • What is a species? • Multiple concepts used; morphological, phylogenetic and biological concepts used most commonly Phylogenetic trees show relationships and times of divergence from common ancestors

3. systematics • Individual species are unique, fundamental units • Distinct in many ways • Isolation – can fuel the speciation • Adaptive radiation • Endemics • Local adaptations • Isolated populations • Remnant populations Basics on how you’d read a tree

4. Systematics • Scientific vs. common names • Common names problematic – observe the following • Gary “I bought you this book on sparrows of the world, it will help you with your research with House Sparrows” • Jodie “Wow, Dr. Dodson, that’s nice, but House Sparrows are weaver-finches, not sparrows” • Gary “Well, then, why the f--- do they call them sparrows?!” • Scientific names, binomial, based on taxonomy, and they are unique • Cardinaliscardinalis– only the Northern Cardinal has this set of names, all populations are covered and it only includes the Cardinalis genus (Pyrrhuloxia, Cardinalissinatus, and cardinals in US)

5. Systematics Cardinaliscardinalis Cardinalissinatus

6. Systematics • Species sorted and described via a nested system that takes relatedness and common characteristics into account • General example below – there are more categories • Class – Aves (all birds) • Order – Piciformes (generally insectivorous birds with zygodactyl feet that forage along tree trunks) • Family – Picidae (Woodpeckers and their close allies) • Picoidespubescens– the Downy Woodpecker, which is closely related to the Hairy Woodpecker (also in genus Picoides)

7. systematics Genus Colaptes Genus Picoides 8.5 12.5

8. Systematics Downy Woodpecker (Picoidespubescens) Hairy Woodpecker (Picoidesvillosus)

9. Systematics • What are the characteristics that are used? • Unique characters will be used to help define related groups and who is related to whom • Foot/toe arrangement • Sperm structure • Organs or specialized tissues – e.g., preen glands, SCS • Bone arrangement, musculature • Plumage characteristics – colors, molting patterns, feather arrangement or structure • DNA or other molecular similarities • Many, many more!

10. Systematics Use of toe arrangement for classification

11. Systematics • Cladistics – study of evolutionary branching sequences • Using character states, as in taxonomy, but to try and define common ancestors and what defines a species • Biochemical Systematics – DNA analysis • Commonality in molecules or DNA sequences can determine relatedness • In most cases all of these methods are used together to determine relatedness, etc. • You don’t always have all the data available

12. Cladograms and parsimony

13. Systematics Here diet and bill morphology used to determine relatedness of Galapagos finches

14. systematics • In the 1990s Sibley and Ahlquist did DNA-hybridization to determine phylogeny • Massive undertaking! • Looked at compatibility of single stranded DNA between putative species • More closely related the two pieces would anneal and stick together fairly well • Less closely related the two pieces wouldn’t anneal well and fall apart easily

15. Here is a potential phylogeny of living avian orders based on morphology (2,954 separate physical characters!).

16. Here is a more recent molecular phylogeny (Cracraft et al. 2004). This shows families, but when families are backed into Orders it has some good agreement with the phylogenies made from morphological characters. Many of the most recent phylogenies try to incorporate molecular, morphological, ecological, and fossil information.

17. Systematics Songbird phylogeny based on DNA

18. systematics • Newest work includes ‘deep time’ • What early ancestral group did birds derive from? • How long ago did this happen? • When did ancestors of modern bird groups first develop?