BIO 5B

• Biology 5B will focus on the functional biology of multicellular organisms (primarily animals and plants, and a little bit of fungi---we are leaving a lot out!)
• Structure and function


  Learn to ask, "How is the structure related to function?"
• Intraspecific variation


  Variation among individuals within species
• Interspecific variation


  Variation among millions of species
• We know there are lots of species on the planet. So far we have described ~2 million. There are perhaps 10-30 million species (most are unknown (bacteria, archea, insects, nematodes, fungi).
• Estimated number of species

  • Plants: ~ 300,000
  • Assorted invertebrates (not arthropods): ~ 150,000
  • Vertebrates: ~ 52,000 (~ 4,500 mammals)
  • Arthropods: > 1,000,000
  • Insects: ~ 1,000,000 (> 350,000 beetles!)
• Huge differences in form and function between these species.
• There are also many fundamental commonalities between the species as well (DNA code, sequence similarity, biochemistry, cell structure, etc).
• DNA sequence difference between any two humans is ~0.1%. Between humans and chimps is ~1.0%
• Phylogeny


  The evolutionary history of a species or group of related species
• Systematics


  The discipline that classifies organisms and determines their evolutionary relationships
• Systematists use fossil, molecular, and genetic data (almost any data) to infer evolutionary relationships
• Phylogenetic tree


  A branching diagram that represents a hypothesis about the evolutionary relationships among various biological species or other entities based on similarities and differences in their physical or genetic characteristics
• Sister taxa are groups that share an immediate common ancestor
• Phylogenetic trees do not indicate when species evolved or how much genetic change occurred in a lineage
• It shouldn't be assumed that a taxon evolved from the taxon next to it
• Homology


  Similarity due to shared ancestry
• Analogy


  Similarity due to convergent evolution
• Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages
• Bat and bird wings are homologous as forelimbs, but analogous as functional wings
• The more complex two similar structures are, the more likely it is that they are homologous
• Shared ancestral character


  A character that originated in an ancestor of the taxon
• Shared derived character


  An evolutionary novelty unique to a particular clade
• Outgroup


  A species or group of species that is closely related to the ingroup, the various species being studied
• Systematists compare each ingroup species with the outgroup to differentiate between shared derived and shared ancestral characteristics
• Cladistics allows the creation of hypothesis about the history of evolutionary change
• Cladistics allows arrangement of knowledge from the most specific to the most general that allows predictions of unstudied organisms (past or present)
• Phylogenetic trees are models that are subject to testing as new information becomes available
• Phylogenetic trees are revised and retested if they do not fit new data
• Phylogenetic trees allow generalizations about the relationships of species without knowing everything about all species
• Molecular analysis showed that whale meat sold in Japanese and Korean markets was from protected species
• Early taxonomists classified all species as either plants or animals
• Later, five kingdoms were recognized: Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia
• More recently, the three-domain system has been adopted: Bacteria, Archaea, and Eukarya
• Horizontal gene transfer is the movement of genes from one genome to another
• Horizontal gene transfer complicates efforts to build a tree of life
• Horizontal gene transfer has played a key role in the evolution of both prokaryotes and eukaryotes
• Eukaryotes can acquire nuclear genes from bacteria and archaea
• The alga Galdieria sulphuraria acquired about 5% of its genes from bacterial and archaeal species