Anatomy, Phylogeny, and Evolution of Animals

The course on the anatomy, phylogeny, and evolution of animals, delivered by Andreas Wanninger at the Department of Evolutionary Biology, aims to provide students with insights into several crucial areas. The primary learning objectives focus on the foundations of comparative morphology across significant animal phyla, key hypotheses concerning the evolution of animals and their organ systems, and current hypotheses about the interrelationships and phylogeny among various animal groups.

Course Delivery and Structure

This course is offered in a hybrid format, combining in-person lectures with additional digital recordings accessible through Moodle for registered students. Lectures will begin on March 3, taking place every Monday from 09:45 to 11:15 and Wednesday from 08:00 to 09:30, with breaks during public holidays and special university events. Students should plan their attendance accordingly as some classes may be canceled.

Lecture sessions will be recorded and materials provided will be available until June 30. It is strictly prohibited to download or distribute the lecture recordings or presentation materials without permission. Examination dates will be posted online, and students are responsible for checking for any changes, as no alternate examination dates will be offered. Students should ensure they are properly registered to attend the examination, as late registrations will not be accepted.

Key Terminology

A central aspect of the course content is the introduction of key terminologies related to animal taxonomy and comparative morphology:

Taxon: A named group of organisms classified as a natural unit, which can be a monophyletic group (e.g., Mammalia) or a paraphyletic group, which doesn't contain all descendants of a common ancestor.
Homologous traits: Features shared by different taxa that can be traced back to a common evolutionary ancestor, like the limb bones in vertebrates.
Analogous traits (or convergent traits): Features that arise independently in different taxa due to similar environmental pressures, such as wings in bats and birds.

Homology and Phylogenetic Analysis

Homology is a relative term that incorporates taxonomic levels. It indicates that homologous traits are the foundation of phylogenetic analyses. Criteria for establishing homology, as outlined by Remane, include:

Criterion of Position: Traits occupying the same position in comparable anatomical structures despite differing functions.
Criterion of Quality: Traits that share specific details even if they may serve different purposes.
Criterion of Continuity: The presence of intermediate forms in the fossil record that demonstrate the evolution of markedly different structural traits.

Embryonic development also contributes to homology, with evolutionary developmental biology (EvoDevo) exploring genetic regulation and the emergence of transient structures that may provide insights into common ancestry.

Evolutionary Principles

The course emphasizes fundamental principles of evolution:

Evolution as a fundamental axiom: Understanding evolution and its mechanisms is considered a foundational principle for further study in phylogenetic systematics.
Descent theory: The concept emphasizes that all species stem from a singular common ancestor, contrasting with creationist views.

Life Domains and Eukaryotic Evolution

In discussing the richness of life, students will explore the domains of life, including:

Eukaryonta: Comprising Protista, plants, animals, and fungi.
Prokaryota: Including Eubacteria and Archaebacteria, which while often categorized together, do not represent a monophyletic group as Archaebacteria are more closely related to Eukaryotes.

Cellular Structures

Students will study the cellular distinctions between prokaryotic and eukaryotic cells. Key features of eukaryotic cells include:

Nucleus with double membranes
Cytoskeleton
Endoplasmic reticulum (involved in protein transport and modification)
Mitochondria
Golgi apparatus

The endosymbiotic theory presents essential insights into the evolution of eukaryotic cells, explaining how ancestral prokaryotes gave rise to organelles such as mitochondria and plastids through symbiotic relationships.

Phylogeny of Eukaryotes

Understanding the phylogeny of eukaryotes reveals the Unikonta-Bikonta hypothesis:

Unikonta: These are eukaryotes with a single flagellum, encompassing amoebas, animals, and fungi.
Bikonta: Representing eukaryotes with two flagella, which includes various protists and land plants.

Amoebozoa and Their Characteristics

The class Amoebozoa, characterized by their unique movement through plasma streams created by actin and myosin filaments, presents a diverse range of organisms including free-living and parasitic species. Noteworthy members include:

Amoeba proteus: A free-living amoeboid.
Entamoeba histolytica: A parasitic amoeba responsible for amoebic dysentery.

Conclusion

As the course progresses, students will delve into the diverse characteristics of various taxa and explore complex evolutionary relationships within the animal kingdom. Understanding these essential concepts will prepare students for evaluating evolutionary mechanisms and conducting phylogenetic analyses in various biological contexts.

Anatomy, Phylogeny, and Evolution of Animals Overview

Anatomy, Phylogeny, and Evolution of Animals Overview