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Flowering plants: split from gymnosperms (pines and conifers) 200-245 mya but crown age much younger ~132 mya
–Grasses did not diversify until ~20 mya
What is the significance of long fuses leading to crown radiations when considering
potential causes of radiations?
species richness (diversity) and morphological diversity (disparity) of tuataras, Welwechia, cordylid lizards, cichlids, parrotfishes, Plethodon salamanders,Geospiza finches, Caribbean island anoles, and coelacanths
You discover a clade of beetles where species differ primarily in the size and shape
of horns, which males use to compete for mates. Is this an ecological adaptive
radiation? Why or why not?
You discover a clade of garter snakes in theSierra Nevada mountains. These species are allopatric and live ingeographically isolated meadows where they feed upon worms and insect larvae.Would you consider them to be an adaptive radiation? Why or why not?
A morphospace is a conceptual array of all possible morphologies.
The bill morphospace shows bills of honeycreepers radiating to diverse bill sizes (width, length and height) to adapt to different food sources.
Explain why a slow-down over time in the rate of speciation and/or character
evolution is a prediction of clades that are undergoing ecological adaptive radiation.
If the speciation rate becomes constant, the more species we should expect later to evolve
The shorter the time we will have to wait for next speciation event
What are the main differences between the adaptive radiation examples we
discussed in class and the paleontological radiations listed in table 14.1?
What is a lineage through time plot? What is the expected relationship between
species richness and time if a lineage is speciating at a constant rate? Why does the
warbler lineage through time plot support the hypothesis that warblers are adaptively
radiating? What other data would you test this hypothesis further?
Why is ecological adaptive radiation easiest to detect in clades which have radiated
Why does the anole example in class support the hypothesis of ecological adaptive
radiation as the cause of anole diversity
What are key innovation hypotheses? What do they attempt to explain?
They are traits that give a lineage ecologicalopportunity. They attempt to explain adaptive radiation.
What are some testable predictions of a key innovation hypothesis?
One can predict that speciation rates will shift at a point on the phylogeny.
What is required for a lineage to diversify?
How can the timing of the origin and subsequent radiation of a lineage be different?
Why is the theory of ecological adaptive radiation important to explaining a fundamental pattern about biodiversity across the tree of life?
How could key innovation, time, and adaptive radiation produced uneven patterns of biodiversity?
Is the FSGD a key innovation for teleosts? Why or why not?
FSGD = Fish specific genome duplication (When fish DNA doubled)
Yes the diversification rate of teleosts increases by 4 times after they require the FSGD. Therefore, the FSGD is a trait shared by the teleosts that allowed them to adaptively radiate.
Exceptionally high diversification rates of percomorphs and ostariophysans are not explained by the FSHD hypothesis.
What are background extinctions and what are mass extinctions?
Background extinctions occur through normal environmental change such as emerging diseases or competition with other species, obliterates certain populations. Mass extinction occurs when at least 60% of the species present are wipes out within 1 million years. During mass extinction species die out due to extraordinary sudden and temporary changes in the environments such as volcanic eruptions or catastrophic sea level changes.
4% of all extinctions have been Mass extinctions
96% have been background extinctions.
Explain the difference between the ‘gambler’s ruin’ and ‘red queen’ hypotheses to explain background extinction. What predictions do these hypotheses make about how long clades will persist or how birth and death rates will change through time?
Gambler’s ruin theorizes that the longer a species lives, the better chance it has of becoming extinct just do to poor or unfavorable odds/conditions.
Red queen proposes that organisms must constantly adapt, evolve, and proliferate not merely to gain reproductive advantage, but also simply to survive while pitted against ever-evolving opposing organisms in an ever-changing environment.
The gist being, tightly coevolved interactions, evolutionary change by one species (e.g., a prey or host) could lead to extinction of other species (e.g. a predator or parasite), and that the probability of such changes might be reasonably independent of species age. Van Valen named the idea "the Red Queen hypothesis," because, under this view, species had to "run" (evolve) in order to stay in the same place.
What are the ‘rise’ and ‘decline’ phases of a fossil clade? How do you recognize them from the fossil record?
Does the mammal fossil evidence favor or disfavor the gambler’s ruin hypothesis?
Mammal fossil evidence disfavors gambler’s ruin hypothesis. Overall, species should last significantly longer than they actually did according to the expected value of the gambler’s ruin hypothesis.
Does the mammal fossil evidence favor or disfavor the red queen hypothesis?
Mammal fossil evidence favors the red queen hypothesis. The expected average origination rates in both the rise and decline phase support the expected value of the red queen hypothesis.
When were the ‘big five’ mass extinctions?
Ordovician: Glacier and sea level changes
Devonian: Global cooling and global warming
Triassic: high C02 levels
34)When did the biggest mass extinction occur?
End of the Permian era wiped out 96% of species.
What traits are associated with extinction risk during periods of background extinction?
Trophic strategy (predator/herbivore)
Do these traits predict survival during periods of mass extinction?
Mass extinction ignores all traits associated with extinction risk in background extinction
Do any traits of species or clades predict survival across mass extinctions?
No. Instead, widespread clades tend to survive mass extinctions better than restricted clades. Other than that, survival is basically luck of the draw.
What is meant by ‘wanton’ extinction?
Wanton extinction refers to the fact that traits that allow survival during mass extinctions are not linked to traits that evolved during background periods.
Basically clades that survive mass extinctions did so coincidentally, and are not necessarily better adapted than the clades that went extinct.
Are the survivors of mass extinctions the best adapted species around at the time?
No because mass extinctions destroy/create a new environment in which organisms live, certain traits are favored and new traits arise creating more diversity.
What are ‘dead clades walking’?
This refers to the fact that even though some clades suve a mass exctinction, they still become marginalized or decrease after the extinction event. (Speciation rate goes down)
43) How long is the recovery phase following a mass extinction compared to the mass extinction phase itself?
The recovery phase is generally much longer than the mass extinction phase. (Permian mass extinction recovery encompassed the entire lower Triassic; 10 million years)
Be able to interpret the morphospace plots for spiny-fins that we went over in class. How do these plots provide evidence for a recovery in the Paleocene that is driven by percomorph spiny-fins?
These plots indicate a change in the environment in which spiny fins have a growing advantage which is seen with the increase in frequency of white dots in the Paleocene area indicating peromorph growth as the morphospace increases.
45)Why do we think that percomorphs evolved new ecological roles in the Paleocene?
Percomorphs evolved new ecological roles in the Pleocene to fill the niches left by non-spiny ray predators that went extinct. They have the same body shapes as the species that went extinct. They are going through adaptive radiation and this is supported by the fossil record.
What are evolutionary trends? How can ecology drive them?
Evolutionary trends are the tendency for traits to evolve in a specific direction with a lineage over time.
Ecology will favor traits that improve performance in weapons, growth (size), and locomotion. (Traits that usually limited by access to resources and competitors)
What are some evolutionary advantages to large size?
Avoid being eaten, better at eating others
Better at your ‘job’. Bigger bodies, bigger brains
Thermal inertia better at weather bad times
Longer period of reproductive activity
Longer lived (less susceptible to predation)
What are some evolutionary advantages to small size?
Less time to grow up
Need fewer resources
Better able to adapt to sudden change
High fecundity (reproduction)
What is Cope’s rule? Does every lineage follow this rule?
Lineages tend to evolve towards larger body sizes (average body size increases over time) Not every lineage follows this rule
Be able to explain why the fossil record of hesperocyonines and borogphagines supports both Cope’s rule and the idea that larger species are more prone to extinction.
Trends towards large size in 3 main subclades of canids (hesperocyonids, borophagines,) The fossil record shows that they have short durations. Extinction rate for largest, most carnivorous species is also highest, because they require the most resources, which can be scarce and are less likely to escape calamities.
How do extinction rates over the last 500 years compare to rates during the big five mass extinctions?
The rates are very similar. If current levels of extinction risk continue, up to 75% of species could be extinct within 540 years.
What is the ‘escape and radiate’ hypothesis? What predictions does this hypothesis make regarding diversification in insect and plant host phylogenies?
The ‘escape and radiate’ hypothesis explains diversification in insects and their plant hosts through coevolutionary processes. Plants evolve innovations to escape predation, which allows for radiation. Predators evolved to overcome defense, which also allows for radiation.
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