Species Concepts (5) Flashcards
Species (in general)?
= organisms that can reproduce naturally with each other & produce fertile offspring.
How do we distinguish species?/ What criteria should we use to distinguish species? (4)
• Morphology.
• Habitat (ecological niche).
• Ability to interbreed.
• Common ancestry/Relatedness (Genetics).
List the Species Concepts (SC)? (7)
• Morphological SC.
• Phenetic SC.
• Biological SC.
• Recognition SC.
• Ecological SC.
• Evolutionary SC.
• Phylogenetic SC.
Morphological SC?
= species is a group of organisms with similar morphological & anatomical characteristics, but are different from other species.
Eg of Morphological SC?
Genus Panthera (“predator of all”) has 4 species (tiger, lion, leopard, cheetah) which differ in pattern, size & skull anatomy.
What does the “most recent” Phenetic SC include?
Quantitative measurements.
What enables you to place individuals in any 1 species?
Diagnostic characters (data types).
Explain the 2 data types?
● Categorical
= grouped.
● Continuous
= data that can take on any value.
Pros of Morphological SC? (3)
• Applies to sexual & asexual organisms (including bacteria).
• Applies to fossils for macroevolutionary studies.
• Enables comparison of fossils & current species.
Cons/Problems of MSC? (4)
• Variation within a species.
• Cryptic species.
• Lack of morphological differences between species.
• Sexual dimorphism.
Biological SC?
= species are members of populations that actually or potentially interbreed in nature.
Eg of BSC? Explain.
Western & Eastern Meadowlarks
- Look similar but don’t interbreed.
- Have different mating songs.
Kinds of reproductive isolating mechanisms? (2)
• Premating/Prezygotic mechanisms.
• Postmating/Postzygotic mechanisms.
List the Premating/Prezygotic mechanisms? (5)
• Ecological/Habitat isolation.
• Seasonal/Temporal isolation.
• Sexual/Behavioral isolation.
• Mechanical isolation.
• Gametic isolation.
Gametic isolation?
= where there is molecular incompatibility of the sperm & egg.
Premating/Prezygotic mechanisms = …?
Gamete related.
List the Postmating/Postzygotic mechanisms? (3)
• Hybrid inviability.
• Hybrid sterility.
• Hybrid breakdown.
Hybrid inviability?
= wherr zygotes are less viable.
Hybrid breakdown?
= where the F2 hybrids are less viable.
Egs of Hybrid sterility? (2)
• Liger (Lion+Tiger).
• Mule (Donkey+Horse).
Cons/Problems of BSC? (5)
• “Potentially interbreeding” suggests separate species & is difficult to determine.
• Asexually reproducing organisms.
• Ring species.
• Chronospecies.
• Hybrids.
Egs of Asexually reproducing organisms as a problem of Biological SC? (2)
• Aspergillus fungi.
• Bacteria.
Ecological SC?
= species is a set of organisms exploiting the same ecological niche.
What controls the division of resources in Ecological SC? (2)
• Ecological processes.
• Evolutionary processes.
Type of selection associated with Ecological SC?
Disruptive selection.
Outcome of Disruptive selection in Ecological SC?
Species formation (speciation).
Why is Disruptive selection associated with Ecological SC?
Why should ecological processes produce discrete species?
Disruptive selection.
Egs of Ecological SC? (3)
• Larvae of maggot flies on Apple & Hawthorn.
• Nematodes (one in humans, other in pigs).
• Dwarf chameleons (one in Western Cape, other in Knysna).
Pros of Ecological SC? (2)
• Apply to hybrids.
• Applies to sexual & asexual organisms.
Cons/Problems of Ecological SC? (3)
• Can miss cryptic species.
• Niches tend to be assumed & difficult to fully define.
• Many taxa exploit overlapping resources, or can switch if a resource becomes scarce.
Eg of Pros of Ecological SC?
Dwarf chameleons.
Phylogenetic SC?
= species is the smallest set of organisms that share an ancestor and are different from other sets.
What is Phylogenetic SC based on?
Character data (morphology + genetics).
What does Phylogenetic SC comprise of?
Speciation events.
Monophyletic?
= group of organisms share exclusive common ancestors.
Do populations share unique derived traits that cause them to cluster together on the tips of a Phylogenetic tree?
It is rare as one needs a really,really good Phylogenetic tree.
Synapomorphy?
= shared derived characters.
Eg of Phylogenetic SC?
Asian & African elephants (divide further into African forest & savanna elephants).
Cons/Problems of Phylogenetic SC? (2)
• Leads to over-splitting as more and more characters are used.
• Hybridization.
Application of Phylogenetic SC?
Polar bears & Brown bears clade (with them not being distinct species).