S2: W8 (Dr. Hanlie) Flashcards
Why do we care about species? (4)
• Might be fundamental units of evolution.
• Units with properties unlike others in nature.
• Important to conserve.
• Units of biodiversity: How many species in an area?
Attributes under Units of biodiversity: How many species in an area? (3)
• Species richness.
• Endemism/uniqueness.
• Rare species; threatened species.
New synthesis under Darwin’s book, On the Origin of Species?
= species was not just another taxonomic rank but, are fundamental units of evolution that do something space & time that genera & families cannot.
Evidences that species are real? (3)
• Everyone can recognize discrete groups in nature (“common sense”).
• Folk taxonomy is equivalent to scientific taxonomy.
• Clusters can be identified statistically.
Species Concepts categories? (4)
• Interbreeding.
• Morphology.
• Ecological niche.
• Common ancestry & relatedness.
Species Concepts under Interbreeding? (2)
• BSC.
• RSC.
Species Concepts under Morphology? (2)
• MSC.
• PSC.
Species Concepts under Ecological niche?
Ecological Species Concept (ESC).
Species concepts under Common ancestry & relatedness? (2)
• Evolutionary Species Concept.
• Phylogenetic Species Concept.
What are Species Concepts based on? (4)
• Reproductive Isolation (Interbreeding).
• Morphological (phenotype) or genetic distinguishability.
• Occupation of a unique ecological niche.
• Lineages through time.
BSC?
= species is a group of interbreeding natural populations that is reproductively isolated from other groups.
BSC attributes? (2)
• Ernst Mayr.
• Concerned about RI mechanisms, prezygotic & postzygotic.
Types of RI mechanisms? (2)
• Prezygotic mechanisms.
• Postzygotic mechanisms.
Types of Prezygotic mechanisms? (5)
• Ecological/Habitat isolation (EI).
• Seasonal/Temporal isolation (SI).
• Sexual/Behavioural isolation (BI).
• Mechanical isolation (MI).
• Gametic isolation (GI).
Mechanical isolation?
= no sperm transferred.
Gametic isolation?
= sperm transferred but no fertilization occurs.
Papers on Species Concepts? (2)
• De Queiroz, 1999.
• Coyne & Orr, 2004.
Prezygotic mechanism?
=
Postzygotic mechanism?
=
Egs of Ecological isolation? (2)
• Tetragnatha spiders.
• Evening primrose, Clarkia species, in California.
Explain Tetragnatha spiders? (5)
• Largest spider radiation in the Hawaiian islands.
• Different ecotypes.
• Differences in spiny leg clade.
• Never occupy the same ecological niche.
• Paper = Gillespia, 2004.
Explain Evening Primrose? (5)
• 2 distinct endemic species in different habitats.
• One Clarkia lingulata is near the Merced river (rare) & the other, Clarkia biloba lives in various woodlands.
• Pollinators unable to tell them apart; numerous sterile hybrids found.
• Chromosomal differences with hybrid breakdown in meiosis (implies cross-pollination).
• Prezygotic & postzygotic isolation.
• Paper = Lewis, 1962.
How is Evening primrose an eg of Prezygotic isolation?
It’s because they were initially in different habitats (habitat isolation.).
How is Evening primrose and eg of postzygotic isolation?
It’s because we crossed them and they produced sterile offspring.
Attribute of Ecological isolation?
Relates to Parapatric or Peripatric speciation.
Egs of Behavioural/Sexual isolation? (2)
• Haplochromine cichlid fish.
• Blue-footed booby.
Explain Haplochromine cichlid fish?
Male colouration which prevents cross-breeding.
Explain Blue-footed booby?
Courtship behaviour through dance.
Eg of Gametic isolation?
Coral species.
Explain Coral species? (3)
• Synchronous spawning occurs on coral reefs.
• About 2/3 of all crosses are incompatible.
• Prevents formation of many inter-species hybrids.
Types of Postzygotic mechanisms? (3)
• Hybrid inviability.
• Hybrid sterility.
• Hybrid breakdown.
Hybrid inviability?
= zygotes are less viable.
Hybrid breakdown?
= F2 hybrids are less viable.
Eg of Hybrid inviability?
Drosophila melanogaster & D. simulans.
Explain Drosophila melanogaster & D. simulans?
Have incompatible nuclear pore protein alleles, which causes hybrids inviability.
Egs of Hybridization that occurs? (2)
● Numerous new species of orchids are created by artificial hybridization each month.
● Drosophila species (sympatric in Hawaiian) hybridize naturally but not often namely, D. heteroneura & D. silvestris.
BSC Pros? (2)
• Helps explain discontinuities among sexually reproducing organisms living in one area.
• Explains why populations fall into discrete groups.
BSC Cons? (5)
• Can’t tell us why/how reproductive isolation develops in the first place.
• Non-dimensional & can only be applied in a single place at a single time (assumes that everything is happening at one place at one time).
• Doesn’t apply to organisms reproducing only asexually/by parthogenesis
• Lacks transivity.
• Is misleading about the process of speciation.
Parthogenesis?
=
RSC?
= species is the most inclusive population of individual biparental organisms which share a common fertilization system.
RSC attributes? (4)
• species mate recognition.
• SMRS.
• True reality of species is adaptive.
• Patterson’s definition.
SMRS stands for?
Specific Mate Recognition System.
Objectives to BSC? (2)
• Assuming prezygotic isolation (strongly conserved by Stabilizing selection).
• Isolating mechanisms (hybrid inviability & hybrid sterility) are non-adaptive & are a result rather than a cause of species separateness.
Egs of RSC? (5)
• Birds of paradise.
• Kori bustard.
• Wandering spiders (Cupierinius).
• Frog mating calls.
• Dewlaps of lizard species of Anolis genus.
Explain Birds of Paradise?
Courtship dance.
Explain Kori bustard?
Courtship display.
Explain Wandering spiders? (4)
● Have 3 phases of courtship in 2 sympatric species:
● ¹Chemical courtship phase:
= male recognizes silk of conspecific female.
● ²Vibratory phase:
= females respond more to vibratory signals of conspecific males.
● ³Tactile courtship phase:
= heterospecific pairings will interrupt the contact phase if courtship has progressed thus far.
RSC Pros? (4)
Can sometimes be:
• Observed.
• Measured.
• Identified.
• Hypotheses tested.
Economic benefits for recognizing species? (3)
• Ecotourism.
• Medicinal purposes.
• Meat cows, milk cows, etc.
MSC?
= species are smallest groups that are persistently & consistently distinct, and distinguishable by ordinary means.
MSC attributes? (2)
• Diagnostic characters.
• Differentiation of internal organs (problem).
Diagnostic characters?
= characters possessed by all (or most) of the members of the species & not by members of other species.
Problems of differentiation of internal organs? (2)
• Impractical as you can’t identify species without dissecting it.
• Conserved features.