BIOL1007 Lecture Notes - Lecture 21: Infraspecific Name, Species Complex, Species Problem

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19 May 2018
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Define the biological species concept and interspecific hybrids.
e.g. colour, shape
Different morphology
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Groups within a species can be defined as being of a taxon hierarchically lower than a
species
Zoology - only subspecies used
Botany - variety, subvariety and form used
Conservation biology - species or smaller distinct population segments
Cryptic species - butterflies have dorsal and ventral
Variation within a species
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In bio - species is one of the basic units of biological classification and a taxonomic rank
Species often defined as a group of organisms capable of interbreeding and producing
fertile offspring
Definitions
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Ernst Mayr - "groups of actually or potentially interbreeding natural populations, which
are reproductively isolated from other such groups
May not be relevant to organisms which asexually reproduct
Organisms that do not interbreed lies outside of defnition
Fossils, clonal species, asexual species
Interspecific hybrids, ring species
Organisms may breed beyond notional definition
Limitations of this concept
Biological species concept
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Ecological species
Biological/isolation species
Genetic species
Cohesion species
Evolutionarily significant unit (ESU)
Phenetic species
Microspecies
Recognition species
Mate-recognition species
Other species concepts
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Capable of forming hybrids e.g. liger
e.g. interspecific hybrids
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Breakdown of reproductive isolating barriers (usually prevents gene flow between
closely related species)
Habitat disturbance - bringing species from previously different environments into
close proximity
Secondary contact - increase migration distances due to change in pollinators or
their movement patterns
Altered phenology of one of both species - leading to overlap in flowering times
Breakdown in pollen incompatability system
Global warming
Potential causes
Sterile, speciation, enhanced variation
Potential evolutionary outcomes
Ring species
Hybridisation
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1. What do we mean by a species?
L21 - do species matter
Monday, 16 October 2017
9:01 AM
mod 4 - ecology and ecosystems Page 1
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When parental population expands around an area of unsuitable habitat so when
2 fronts meet they behave as distinct species while still being connected through a
series of intergrading populations
Ring species
Provide arguments in the debate about the species problem.
Hard to define species
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Differing measures often used e.g. similarity of DNA, morphology, ecological niche
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Presence of specific locally adapted traits may further subdivide species into "infraspecific
taxa" such as subspecies
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Many organisms don't conform to the reproductively isolated criteria
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Not possible to test this for fossil taxa
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Species problem
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Describe what is known about the number of species and how this
varies globally, by region, and by group.
Globally, by region, by group?
Monotremes = 2
Marsupials = 46
Rodents = 17
Bats = 37
In NSW (102)
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Described species = 19324
Estimated 21645 species
Vascular plant flora of Aus
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Mammals 4004
Birds 9020
Fish 18818
Plants 255000
Fungi 70000
Total 356842
Worldwide
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Some say about 10 million
Total number uncertain because a lot not described yet
Most non-insects probably discovered and described, most insects never will be
Estimates depend on source
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Count number of beetles on one tree
Used insecticide fog in canopy, so insects die and fall into collecting devices
19 individuals of a leguminous tree
9000 beetles -> 1200 beetle species
Based on extrapolations 13.5% beetles live only on this one tree species and
approx 50000 tropical trees
Erwin (1982) - how many insect species in tropical rain forest
Extrapolation examples
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2. How many species are there?
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