morphology, classification, and phylogenetics · pdf filetaxonomy: deals with describing...

Morphology, Classification, and Phylogenetics

Biology of Fishes 9.11.2012

Review

Basic Fish Morphology

Classification

Phylogenetics

Overview

Adaptations to diverse environments

Symbiotic Relationships

Life History & Reproductive Strategies

Diadromy (anadromous, catadromous)

Sequential hermaphroditism (protandry, protogyny)

Ecology & Conservation

Invasive species

Habitat loss

Overfishing

Review

Northern Snakehead (CHANNIDAE)

Basic Fish Morphology

Basic Fish Morphology

Great White Shark

Basic Fish Morphology

Lungfishes

Basic Fish Morphology

Muskellunge

American Eel

Why do we do it?

Simplification – reduce complexity of ~28,000 species

Communication – stable, shared information system

Prediction – infer qualities about unexamined species

Taxonomy & Systematics

Phenetics & Phylogenetics

Classification

Taxonomy: deals with describing biodiversity, including naming undescribed species

Systematics: focuses on relationships among species or higher taxa

Phenetics (Linnaean system)

Phylogenetics

Classification

Taxonomy & Systematics

Cow, lungfish, salmon

Phenetics (Linnaean system, traditional)

Kingdom Phylum Class Order Family Genus Species

Based on similarity of characters (advanced, primitive, or lacking). “look similar = share similar evolutionary history”

Cow Lungfish, Salmon

Classification

Phenetics (Linnaean system, traditional)

Kingdom - Animalia

Phylum - Chordata

Class - Actinopterygii

Order - Perciformes

Family - Percidae

Genus - Perca

Species - flavescens

Classification

Yellow Perch

Taxonomy

Phylogenetic systematics (cladistics) - alternative classification, widely accepted

Cow, Lungfish (Sarcopterygii) Salmon (Actinopterygii)

Apomorphies, synapomorphies, plesiomorphies

Monophyly, paraphyly, polyphyly

Parsimony

Classification

Study of evolutionary relationships among groups of organisms. A phylogeny is a history of taxonomic groups.

Phylogenetics

A phylogeny is a history of taxonomic groups

Phylogenetics

Phylogenetic systematics (Cladistics)

Requires identification of characters as either apomorphies or plesiomorphies

Apomorphies: derived (or “advanced”) characters that arise from speciation events

Plesiomorphies: ancestral, less derived (“primitive”) characters

Synapomorphies: shared derived characters or shared specializations

Symplesiomorphies: shared ancestral characters

Phylogenetics

Phylogenetics

A: Ray-finned (Actinopterygii) B & C: Lobe-finned (Sarcopterygii)

Phylogenetic systematics (Cladistics)

Goal is to find synapomorphies to identify monophyletic groups or clades

A clade includes a common ancestor and all of its descendants (monophyletic)

Phylogenetics

Cladogram – branching diagram of genealogical relationships

Phylogenetics

Monophyletic: Reptiles & Birds (includes common ancestor and all descendants) Paraphyletic: Reptiles (includes most recent common ancestor but NOT all descendants) Polyphyletic: Warm-blooded Animals (does NOT include most recent common ancestor of its descendants)

Phylogenetics

Construct a cladogram that includes the following groups:

Holostei (Gars & Bowfins)

Chondrostei (Sturgeons & Paddlefishes)

Dipnoi (Lungfishes, tetrapods)

Teleosts (“modern” bony fishes)

Cladistia (Bichirs)

Actinistia (Coelacanths)

Phylogenetics Assignment

A B C D E F

SARCOPTERYGII

ACTINOPTERYGII

Phylogenetics Assignment

Construct a cladogram that includes the following groups:

Label Groups on Cladogram/Tree

List sources; at least 2 (website, text, journal article)

Turn in Thursday at beginning of lecture

Phylogenetics Assignment