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.
Egs of MSC? (2)
• Gladiolus species (Iridaceae).
• Orioles species (European golden, African golden, Blackheaded).
Phenetic SC?
= species are the lowest level at which distinct phenetic clusters can be observed.
Phenetic SC attributes? (3)
• Uses as many characters as possible.
• Recognizes phenetic clusters by multivariate statistics.
• Updated, numerical form of the MSC.
Eg of Phenetic SC?
Scattergram & Phenogram with fish.
Phenetic SC Cons? (3)
• Lacks a sound philosophical basis.
• May get different patterns from different analyses.
• Subjectivity [At what point does one draw the line (in clustering) or outline the group (in scattergrams)].
Ecological SC?
= species is a set of organisms exploiting a single ecological niche.
Modified definition of Ecological SC?
= a lineage (or several closely related lineages) which occupies an adaptive zone in its range different from any other, and which evolves separately from any lineage outside its range.
Who gave the modified definition of Ecological SC?
Van Valen.
Egs of the Ecological SC? (2)
• Finches on Galapagos islands.
• Anolis species.
Explain Finches on Galapagos islands? (3)
● Tree finches had parrot-like bills & probing bils.
● Ground finches had crushing bills.
● Warbler finches had probing bills.
Explain Anolis species? (2)
• Different ecological niches.
• On Puerto Rico Caribbean island.
Evolutionary SC?
= species is a lineage evolving separately from others & with its own evolutionary role and tendencies.
Evolutionary SC attributes? (3)
• Simpson; Wiley.
• Species are historically unique lineages extending through time (ie., included a sense of evolutionary history in the concept).
• Species are therefore segments of lineages.
Lineage according to Evolutionary SC?
= a series of entities forming a single line of direct ancestry & descent.
Outline process of how lineages evolve? (3)
● At initial branch
• beginning of speciation.
• divergence of organisms begins.
● At branch node
• gene flow is gradually lost.
• phenotype distinctions may appear.
• gene tree becomes more distinct.
● At branch terminal points
• end of speciation.
• species recognized by all criteria.
At initial branch? (2)
• beginning of speciation.
• divergence of organisms begins.
At branch node? (3)
• gene flow is gradually lost.
• phenotype distinctions may appear.
• gene tree becomes more distinct.
At branch terminal points? (2)
• end of speciation.
• species recognized by all criteria.
General lineage concept paper?
de Queiroz, 2007.
Phylogenetic SC keyword?
Genetically monophyletic.
Phylogenetic SC 1?
= species is the smallest sample of self-perpetuating organisms that have unique sets of characters.
Phylogenetic SC 2?
= species is the smallest, exclusive monophyletic group of common ancestry.
Phylogenetic SC is AKA? (2)
• Cladistic SC.
• Diagnostic SC.
Egs of Phylogenetic SC? (2)
• Philothamnus sp. boundaries.
• Polar bears (Ursus maritimus) & Brown bears (Ursus arctus).
Explain Polar bears & Brown bears?
Same species genetically & phylogenetically.
Problem with applying SC?
Cryptic species.
Eg of cryptic species?
Neotropical Skipper butterfly.
Explain Neotropical Skipper butterfly? (5)
• Complex of 10 mostly Sympatric species.
• Identified using COX1 gene.
• Adults under subtle differences.
• Caterpillars & their food plants distinct.
• Hebert et al, 2004.
MSC vs PSC?
● MSC
= similarity in form.
● PSC
= diagnostic features.
BSC vs RSC?
● BSC
= interbreeding.
● RSC
= SMRS.
Ecological SC keyword?
Distinct ecological niche.
Evolutionary SC keyword?
Changes within lineages (angenesis).
Phylogenetic SC keywords? (3)
• Common ancestry.
• Monophyly.
• Derived distinct features.
Hybridization?
=
Egs of Evidences for Hybridization? (2)
• Rhodohypoxis (red) & Hypoxis (yellow) = Hybrid (pink).
• Swordtail fish.
Explain Swordtail fish? (2)
• Novel morphologies.
• Range of traits.
Possible outcomes of Hybridization? (3)
● Introgression & Reinforcement.
● Hybrid swarms (multiple matings).
● Hybrid speciation.
Eg of Introgression?
Louisiana irises.
Explain Louisiana irises? (2)
● I. falve lives in riverine habitat, while the I. brevicaulis lives in swamps & marshes.
● Hybrid adults & seeds show asymmetric introgression.
Kinds of hybrid speciation? (2)
• Homoploid speciation.
• Allopolyploid speciation.
Asymmetric introgression?
= when genes move more go one species than they do to the other species.
Results of introgression? (2)
● Introgression of a few loci can promote adaptive divergence & accelerate speciation.
● Recombinant hybrid genome.
Reinforcement?
= process where natural selection increases reproductive isolation through the decrease in hybrid fitness.
Why does NS increase RI?
To decrease hybridization.
Introgression & Reinforcement are examples of what?
Secondary gene flow.
Introgression?
= movement of gene(s) from one species into another by repeated backcrossing between a hybrid and one of its parents.
Explain introgression using the A, B & C?
Basically, A + B cross as parent species and produce C, a hybrid. C can then mate with either A, B or both A and B at different times, ie., C can backcross with A, B or both. Backcrossing basically meaning to go back and cross with another species.
Thing to note on Reinforcement? (2)
● Character displacement occurs but from a reinforcement perspective.
● Look at character displacement from a Reinforcement perspective & NOT an ecological perspective as in previous lectures (remember the eg of frogs that were separated and then when they reunited they had completely different calls due to their different habitats?). When looking at this eg from a Reinforcement & Hybridization perspective under character displacement, the hybrid of the two parent species has a call that is completely different from the parent species.
Eg of character displacement from ecological perspective?
African barbets (tinkerbirds).
Eg of Reinforcement?
Phlox species.
Explain Phlox species?
Hybrid fitness is decreased, that’s why you have hybrids in the contact zone (where the regions of the parents overlap) only and not in the regions of the parent species.
Explain African barbets? (4)
• Some changes in sympatry.
• Not reinforcement.
• No hybrids.
• In zone of contact.
Hybrid swarms attributes? (3)
• Viable hybrid offspring that interbreed among themselves & with parent genotypes.
• Highly variable.
• Is a result of backcrossing.
Eg of Hybtid swarms?
Penstemon hybrids.
- P. spectabilis & P. centranthifolius.
Possible speciation outcomes? (2)
• Introgression & Reinforcement.
• Homoploid & Allopolyploid speciation.
Homoploid speciation?
= where hybrids maintain the same chromosome number as the parents even though they look different (different morphology to parents but same chromosome number as parents).
Egs of Homoploid speciation? (2)
• Heliconius butterflies.
• Helianthus (sunflowers) hybrids.
Explain Heliconius butterflies? (3)
• different wing colour patterns result in immediate RI.
• wing colour is controlled by 4 gene loci.
• Paper = Mavarez et al., 2006.
Explain Helianthus (sunflower) hybrids? (3)
• one consequence is species formation.
• adaptive convergence in novel/different habitats.
• H. annuus + H. petiolarus = H. anomalus.
Allopolyploid speciation?
= eg, where diploid become tetraploids.
[Basically, 10 (parent 1) + 10 (parent 2) = 20 (hybrid), but that’s not always the case. As seen when 10 (parent 1) + 20 (parent 2) = 15 (hybrid). Shows that the numbers are not always doubling and gives us an idea of what may happen if you do have parent species that cross unequally].
Eg of Allopolyploid speciation?
Tragopogon.
All species equal? What to conserve?
Extinctions attributes? (3)
• 50-500X BR.
• 3000-30000 species go extinct.
• Threatened species.
List of threatened species from highest to lowest? (6)
• Amphibians.
• Sharks & rays.
• Reef-building corals.
• Conifers.
• Mammals.
• Birds.
IUCN Red List categories indicating threat? (3)
• CR (Critically Endangered).
• EN (Endangered).
• VU (Vulnerable).
IUCN criteria for assessing threat to species? (5)
• Population reduction.
• Restricted geographic range.
• Small population size & decline.
• Very small or restricted size.
• Extinction probability analysis.
After criteria for assessing threat to species?
Numerical thresholds are fone to determine whether a species is endangered or not.
Eg of a naturally rare species?
Satyrium liltvedianum.
Explain Satyrium liltvedianum? (2)
• Kogelberg mountain in the Cape Floristic Region.
• 1 population.
IUCN Red List attributes? (3)
● A critical indicator of the health of the world’s biodiversity.
● A powerful tool to inform and catalyze action for biodiversity conservation & policy change.
● Helps inform necessary conservation decisions.
Eg of ancient taxa?
Tuatara- Sphenodon.
Explain Tuatara? (7)
• Lizard-like reptile.
• Flourished over 200mya.
• Now confined to 30 small islands off the coast of New Zealand.
• 3 species were recognized.
• Is an eg of a priority species.
• Is now LC due to breeding projects.
• Only one in its order out of 4 orders.
Egs of other living fossils? (2)
• Welwitschia mirabilis.
• Coelacanth (Latimeria chalumnae).
Explain Welwitschia mirabilis?
Only 3 extant genera in the entire phylum.
Explain Coelacanth?
One of the only 4 living genera of the lobe-finned fish, including lung fish.
Why are living fossils important?
They’re important for understanding biological diversity & evolutionary process.
Thing to note for Taxonomic/Genetic distinctiveness?
Species of monotypic genus receive the highest priority.
Taxic diversity?
=
Phylogenetic diversity?
=
Integrative approach to species recognition attributes? (3)
• Use the taxonomic circle.
• Damm et al (2010).
• NB: Use as many lines of evidence as possible to better delineate species.
Explain Damm et al (2010)? (2)
• Dragonfly species.
• Used integrative approach to discover new (cryptic) dragonfly species (African dragonfly).
