Evolution: Animal Diversity - Part 1

Biology 155

Krilowicz

Spring 2010

I. Definitions

A. Taxonomy: the science of classification of living things; older schemes were constructed without regard for evolutionary relationships among organisms

B. Phylogeny: the science that examines the evolutionary relationships among organisms; most taxonomic schemes in use today are based on phylogeny

II. What types of information can be used to construct phylogenetic

schemes?A. Anatomy: similarities or differences in structure

of modern day forms1. Adult structures –

The bones of a human arm are very similar to those in a bird wing, so probably closely related animals (homologous structures)

The vertebrate limbs are very different from arthropod limbs, so these two groups are more distantly related

Various arthropods

Various vertebrate forelimbs

Fig. 13.5A

II. What types of information can be used to construct phylogenetic

schemes? - continuedA. Anatomy: similarities or differences in

structure of modern day forms – continued2. Embryonic structure –All vertebrate embryos go through very similar

developmental patterns, so probably closely related animals

The development of vertebrates (deuterostomes) differs from arthropods (protostomes), so these two groups are more distantly related

Two vertebrate embryos at similar stages in

development

Fig. 13.5B

II. What types of information can be used to construct phylogenetic

schemes? - continuedB. Physiology: function of present day organisms

Mammal and reptile lungs function in essentially the same manner, so probably closely related animals

Insects use a tracheal system to exchange gases that functions very differently from vertebrate lungs, so these two groups are more distantly related

II. What types of information can be used to construct phylogenetic

schemes? - continuedC. Geologic (Fossil) Record: can be used to

determine –

1. Anatomy of extinct organisms

2. First appearance of currently living organisms

II. What types of information can be used to construct phylogenetic

schemes? - continuedD. Biochemical Information: how similar is

the structure of enzymes, ribosomes, etc. among groups of organisms?; Reflects similarity in DNA because information in the genes is used to construct proteins, RNA and other biological molecules

II. What types of information can be used to construct phylogenetic

schemes? - continuedE. Gene (DNA) Sequence Data – how

similar is the genetic material among living organisms? ultimately what scientists really want is an answer to this question to definitely construct phylogenetic trees

Has recently led to a reorganization of living things into three domains versus five kingdoms

Three domain system of classification

Five kingdom system of classification

III.The Taxonomic Hierarchy:

Domain (three of these)

Kingdom

Phylum (Animals) or Division (Plants)

Class

Order

Family

Genus

Species

Increased relatedness = more traits in common

Only group with a biological definition

Definition of a species

• A group of actually or potentially interbreeding organisms that are reproductively isolated* from other organisms

* Either cannot mate with another organism or mating produces sterile offspring

Species names have two parts

Genus species

Capitalized lower case

italicized italicized

Usually Latin

Example – Felis domesticus