Figure 6.3 Linnaean Classification of the Domestic Dog

Linnaean Classification of the Domestic Dog

How Did the Enormous Variety of Species Arise on Earth?

Many genetic mechanisms are conserved from bacteria to homo sapiens.

Mutations are spontaneous changes in genes, a rapid form of evolution.

Genetics—the study of the mechanisms of inheritance that began with Mendel and DeVries.

Natural Selection at the Genetic Level

Family Tree of Apes and Humans

Why Should We Study Other Species?• Different kinds of animals have evolved:

– specific behaviors and neural mechanisms

– exploit specific sets of environmental opportunities, or ecological niches.

• Differences in brain size and structure can be due to behavioral adaptations

• Novel or strategic food-seeking behavior is correlated with larger brain size.

Food Storing Birds

Brainy Warblers Sing More Songs

A Comparative View of Nervous Systems

Functions and Relations: basic sensory cortical areas for Mammals

Human and Rat Brains Compared

The origin and evolution of synapses• Proteomic studies

– molecular components of postsynaptic proteins

– mice have approximately 1,500 postsynaptic proteins• such as ion channels, receptors, cell adhesion and cytoskeletal proteins, kinases and

phosphatases, scaffolding proteins and signalling molecules

– Compare species to form a phylogeny of the molecular components of the synapse

– use of comparative genomics to examine how and when synaptic proteins originated and diversified

• Protosynapse– ancestral molecular biology of unicellular organisms, yeast, amoeba,

choanoflagellates as well as multicellar sponges

– existed before the evolution of metazoans and neurons

• True synapse – Early metazoans such as sea anemones, jellyfish

– More complex receptors in Protosomes such as earthworm and molluscs