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Introduction
 Introduction Resource- This unit is concerned with macroevolution – the patterns and processes of evolution above the species level.
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1 Systematics and the reconstruction of phylogeny
- 1.1 Introduction Resource
- To the lay person, it might seem
surprising that there is any problem with the recognition of higher
taxa. The very existence of long-established vernacular names for
inclusive groupings of species (e.g....
- 1.2 Taxa and relationships Resource
- Until the mid-20th century,
inferences about evolutionary relationships between species were
generally based upon as wide a range of evidence as could be mustered.
Evolutionary systematics is the name...
- 1.3 Relationships between species Resource
- Using the idea of blood
relationships in people as an analogy, can you think of two distinct
types of relationship between species?
- 1.4 Grades and clades Resource
- If species are grouped together
because they show a similar extent of accumulated anagenetic change
with respect to their ancestors, then the taxa so formed constitute
grades. In Figure 1, morphological...
- 1.5 Clades and mammals Resource
- Are the mammals a clade?
- 1.6 Clades and reptiles Resource
- Are the reptiles a proper clade?
- 1.7 Homologies Resource
- If homologies could be recognised
as such, then the relationships between species could be inferred from
their shared homologies. Unfortunately, however, homologies and
analogies cannot always be unambiguously...
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2 A first approach to systematics
- 2.1 Introduction Resource
- The late Dr. Colin Patterson was
a palaeontologist at the Natural History Museum, and an authority on
systematic methods. He played a prominent role in promoting cladistics,
the method now most widely...
- 2.2 Darwin, Linnaeus and Simpson Resource
- In the first clip, Dr. Colin
Patterson introduces and explains Darwin’s ‘tree of life’, image, shown
below (Figure 3). This was the only image included in his book, Origin
of Species.
- 2.3 What does relationship mean in systematics? G.G. Simpson Resource
- Dr. Patterson continues to look
at Simpson’s answer to the meaning of ‘relationship’ in systematics,
and illustrates this by referring to a diagrams showing how the
systematist viewed the relationship...
- 2.4 What does relationship mean in systematics? E. Mayr Resource
- Dr. Patterson looks at the second
of his three systematists, Ernst Mayr. Mayr’s answer to the meaning of
‘relationship’ in systematics comes from the point of view of an
evolutionist. This clip refers...
- 2.5 What does relationship mean in systematics? W. Hennig Resource
- In this clip, Dr. Patterson
introduces his third systematist, a German entomologist named Willi
Hennig. This offers a third meaning of ‘relationship’, which is
illustrated through a diagram showing Hennig’s...
- 2.6 Three schools of classification Resource
- This clip explores the three
kinds of relationships that have been explained so far, in terms of the
work of Simpson, Mayr and Hennig, which are referred to as Simpsonian,
Mayrian and Hennigian relationships....
- 2.7 Inferring relationships of common ancestry Resource
- This clip addresses the question
of how one might go about building a tree, or inferring relationships
of common ancestry, by recognising evolutionary novelties, or shared
derived characters, or synapomorphy....
- 2.8 Systematic hierarchy Resource
- This clip builds on the idea that
development recapitulates systematic hierarchy, by trying it out with
the wrist bones of hominoids.
- 2.9 Conflicting morphological characters Resource
- This clip looks at conflicting
morphological characters and at how it is possible to resolve them,
with the aid of a table of molecular characters (Figure 9).
- 2.10 Chimps, gorillas and humans Resource
- Dr. Patterson uses a diagram
showing alternative cladograms for humans, chimpanzees and gorillas
(Figure 10) to summarise evidence supporting the hypothesis that chimps
are our closest relatives. He also...
- 2.11 Consequences of human / chimp pairing Resource
- This clip refers back to the
table of molecular characters, which is shown again here (Figure 9). It
explains the consequences of human / chimp pairing in terms of
homologous and non-homologous characters....
- 2.12 Translating a cladogram into a classification Resource
- This clip begins with a diagram
by Ernst Haeckel published in 1866 (Figure 11). This is an illustration
of how little ideas on the relationships of higher primates have
changed in over a century.
- 2.13 Systematics and biogeography Resource
- In this clip, Dr. Patterson
introduces the concept of systematics and biogeography. He uses a
diagram showing two cladograms (Figure 13) – one representing the
higher primates that have been discussed...
- 2.14 Summing up Resource
- Dr. Peterson concludes the audio sequence with a summary of all the points covered.
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References and Acknowledgements
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