This is a widescreen fully animated and editable PowerPoint presentation that covers section 2.4 of the Cambridge Pre-U Biology course. It is 36 slides long and covers the following topics: Species concept Classification systems The full PowerPOint can be downloaded here: https://sellfy.com/p/XECT/

1. MAKING SENSE OF
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2. Copyright © 2017 Henry Exham
• In 1758 Swedish scientist Carl Linnaeus created a
system for categorising and naming living organisms.
• We still use the same system today and to date have
described and entered into databases 1.25 million
species (with a further 700,000 described but not yet
entered into the databases).
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In 2016 new DNA sequencing research
from Indiana University suggests Earth
could contain nearly 1 trillion species
(including bacteria and archaea).
Kenneth J. Loceya, and Jay T. Lennona. Scaling laws predict global microbial
diversity. PNAS, 2016 DOI: 10.1073/pnas.1521291113

3. MAKING SENSE OFMAKING SENSE OF
The Species Concept
Classification Systems
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a) Define the term species with reference to morphological,
genetic and biochemical similarities, and capability to
produce fertile offspring.
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• Actually defining exactly what a species is is harder
than you may think. There’s no one definition that will
always work and taxonomists use different rules in
different situations.
• They call these rules ‘species concepts’ and these are
the most popular:
– Biological species concept.
– Phylogenetic species concept.
– Morphological/phenetic/typological species concept.
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• Each concept is really a set of criteria that scientists can use to decide if
organisms are in the same species. They don’t work for all organisms and so
its more of a tool than a rule.
• These concepts may consider various characteristics to determine if
organisms are from the same species:
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Morphology (physical features)
Biochemistry
Physiology
Embryology
Behaviour
Ecological niche
Reproductive isolation
Evolutionary relationships
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