BIOL1007 Lecture Notes - Lecture 21: Infraspecific Name, Species Complex, Species Problem
Define the biological species concept and interspecific hybrids.
e.g. colour, shape
○
Different morphology
-
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
○
Horticulture - cultivars
○
Cryptic species - butterflies have dorsal and ventral
○
Variation within a species
-
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
-
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
-
Ecological species
○
Biological/isolation species
○
Genetic species
○
Cohesion species
○
Evolutionarily significant unit (ESU)
○
Phenetic species
○
Microspecies
○
Recognition species
○
Mate-recognition species
○
Other species concepts
-
Capable of forming hybrids e.g. liger
○
e.g. interspecific hybrids
-
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
-
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
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
-
Differing measures often used e.g. similarity of DNA, morphology, ecological niche
-
Presence of specific locally adapted traits may further subdivide species into "infraspecific
taxa" such as subspecies
-
Many organisms don't conform to the reproductively isolated criteria
-
Not possible to test this for fossil taxa
-
Species problem
-
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)
-
Described species = 19324
○
Estimated 21645 species
○
Vascular plant flora of Aus
-
Mammals 4004
○
Birds 9020
○
Fish 18818
○
Plants 255000
○
Fungi 70000
○
Total 356842
○
Worldwide
-
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
-
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
-
2. How many species are there?
mod 4 - ecology and ecosystems Page 2