Lecture 9 - Insect Phylogeny & Systematics

Question 1

Systematics

Answer 1

• concerned with understanding the diversity of organisms and their interrelationships
• 2 Major sub disciplines: Taxonomy and Phylogenetics

Question 2

Taxonomy

Answer 2

discovery and delimitation of species, and their placement in a higher (more exclusive) classification

Question 3

Plylogenetics

Answer 3

the study of the evolutionary relationships among organisms

Question 4

What are the 2 fundamentally important categories of names?

Answer 4

• Species: basic unit in biology

- Family: used to communicate information to non-taxonomists (In insects, family is more informative than species)

Question 5

Speciation

Answer 5

• differentiation within a population of 2 different groups

- caused by division or isolation of small populations

Question 6

Extrinsic vs Intrinsic

Answer 6

• Extrinsic (external factors): physical isolation of fringe populations, EX: volcanoes, distribution of lubber grasshoppers in certain location in US
• Instrinsic (internal factors): changes in mating displays, coloration, genes within population, EX: different colored insects

Question 7

Biological species concept

Answer 7

a species is a population or populations reproductively isolated from other populations

Question 8

Morphological species concept

Answer 8

a species is defined by uniques combinations of structural characterisics, or discontinuities in structure between groups of organisms

Question 9

Phylogenetic species concept

Answer 9

members of a species share derived characteristics that separate them from all related groups

Question 10

Explain species names

Answer 10

• 2 word (binomial) names: Genus & species
  -in Greek or Latin
  -both names are ALWAYS italicized or underlined
  -Genus is ALWAYS capitalized (genus-singular, genera-plural)
  -Species NEVER capitalized (species singular and plural), the followed by the name of the describer, which is not italicized or underlined
  EX: Apis mellifera Linnaeus

Question 11

History of taxonomy

Answer 11

• Aristotle developed 1st principles of biolocaly classification, then became formalized in Europe in 1700s
• Accepted nomenclature begins with Linnaeus’ 1758 Systema Naturae
• Animal & microbial names begin in 1758

Question 12

Holotype

Answer 12

• species placeholder based on one specimen

- kept protected in museums

Question 13

How are species classified?

Answer 13

In groups according to similarity or relatedness - referred to as taxa (plural), taxon (singular)

Question 14

Cladogram vs Phylogram

Answer 14

• Cladogram: tree-life diagram depicting estimated sequences of splitting events (speciation events)
• Phylogram: a phylogenetic tree with branch lengths reflecting distance between splitting events

Question 15

Monophyletic group vs Paraphyletic vs Polyphyletic

Answer 15

Monophyletic group: consists of the most recent common ancestor & all descendants; called a clade
Paraphyletic group: doesn’t contain all descendants
Polyphyletic group: excludes the most recent common ancestor

Question 16

Parsimony methods

Answer 16

used to reconstruct a tree that implies minimal amount of character change among group members = most parsimonious tree (or tress)

Question 17

Likelihood methods

Answer 17

(use DNA sequence data), use model of evolution (e.g. nucleotide substitution) to search for tree that maximizes the fit between observed data, and the model
= maximum likelihood tree.

Question 18

6 Major events in insect phylogeny

Answer 18

1. Establishment of basic hexapod groundplan: 3 pairs legs and 3 body segments
2. Origin of wings
3. Wing flexion
4. Holometaboly
5. Co-evolution with angiosperms
6. Evolution of social behavior: independently in several groups (termites , ants, bees & wasps