As palaeo-/neobotanists, we often pondered about the distribution of modern plants, and how history (we are talking about millions of years) shaped those.
The discipline putting up explicit scenarios is called "biogeography". The papers usually show a so-called "areagram", a graph depicting a phylogenetic tree where all nodes are labelled to indicate the modern (in the case of the tree's tips) and reconstructed "ancestral" area. An ancestral area is the part of the Earth reconstructed to be the place of origin for a lineage.
However, when you read one of our biogeographic papers, including the ones published in the Journal of Biogeography, you often won't find an areagram. For a simple reason, either our data were (and still is)
- too complex for an explicit biogeographic analysis (The challenging and puzzling ordinary beech),
- too trivial to bother about it,
- or we knew, because of the fossil record, that the modern distribution is unrepresentative or even violates the basic assumptions behind even the most sophisticated ancestral area reconstructions.
Plants don't walk but they can still migrate. And their pollen and some of their seeds are dispersed by wind and water. Hence, when doing biogeography, it cannot hurt to get familiar with Earth's dynamic atmosphere and hydrosphere. And this is how I found one of the most beautiful online services (not only for scientists)
earth:: a global map of wind and water https://earth.nullschool.net/
When you open the link, you'll see something like this (the real stuff is animated not static, but I have no idea how to capture an animated gif).
This is Earth just now (well, when I wrote the post). The colouration gives the wind speed (blue: no/little wind; green: wind speeds of ~ 50 km/h. Let's turn the world a bit and zoom in on something interesting currently happening: level 5 cyclone Harold (Wikipedia).
|Tropical cyclone Harold-2020, roaming the empty vastness of the "Silent Ocean". The white arrows give the local wind patterns (direction and speed), the colouration the speed (blue: slow, red: very fast).|
You can click on any place (the little lush green circle), and a little info window pops up telling you where you are, and the actual situation you are looking at, at that very spot.
But there is much more. Let's click on "earth" on the lower left corner and pop up the menu.
- Date: Time displayed (default: now)
- Data: Displayed/ animated data
- Scale: the colouration scheme used for the overlay ("Wind")
- Source: Data source
- Control: Time control, fast forward and backward goes one day forth and back, +/- one hour, the calender button let you choose a specific date; "Grid" display a dotted grid reflecting the data points for the display/animation (the latidute and longitude lines are 10°-lines, the grid points 0.5°); play button starts/stops animation; HD increases the grid points (requires a fast internet connection and well-equipped computer).
- Mode: what to select as Overlay
- Air: atmospheric conditions such as wind, temperature, and moisture
- Ocean: hydrospheric conditions such as ocean current, waves, and temperature
- Chem: concentration of natural and artificial (human-made) pollutants (CO, CO2 and SO2)
- Particulates: atmospheric particles
- Space: Probability to see the Aurora borealis.
- Height (only with mode "Air"): at which part of the atmosphere we are looking at, the height is not express in meters above sea-level but in atmospheric pressure (hPa).
- Animate (only with mode "Ocean"): what to animate, current or waves?
- Overlay: what is visualised, the selection depends on the set Mode. Hoover over the abbreviations to see what they stand for. The handiest for everyday are:
- Wind (orange, since currently active): wind direction and speed.
- Temp: temperature
- RH: relative humidity
- TPW: total precitable water, the water in the atmosphere that may (or is) rain(ing) on you
- MI: misery index, how nice would it be for humans to stroll around (well, I can't these days anyway because of the French complete Coronavirus lockdown).
- Projection: how to project the Earth. Standard setting is "O" = orthographic, i.e. the 3D reality is projected to 2D plane by parallel projection—a projection already used early on to make maps that distorts forms close to the margins. A comprehensive overview over projections and their up- and downsides can be found on Wikipedia (of course).
Watch the seas
You may have heard of the Gulfstream, the ocean current that makes sure Europe isn't covered by glaciers (again) and comparably mild in respect to the same latitudes in North America and East Asia)? Let's roll the globe, select Mode: Ocean, Animate: Currents, Overlay: SST (sea-surface temperature).
|Making Europe a comfy place to live: the Gulf Stream|
As I was told by a colleague these days, spring started not only pretty late and chilly in Europe but also in Alaska, where you still can enjoy heavy snows (unusual for this time of year). One reason is probably that this year a warm ocean current, the Kuroshio Current – passing the south coast of Japan and transporting tropical heat deep into the North Pacific – is not as strong as last year. (PS the weakening of the so-called Global Ocean Conveyor Belt that transports cold and warm waters all over the globe, was a projected consequence of human-made climate warming; its motor is fueled by heat differences between low- and high-latitude seas and within the water body but both the equatorial and polar waters heat up.)
|The North Pacific, captured two days ago (bottom) and same view one year earlier (top), triggered using the calendar option.|
Not a few of us are now in home office for reasons of social distancing to slow down the spread of this year's plague—flatten the curve. But that doesn't mean, we get around the usual boring and pointless meetings with unwitting superiors or other people that just don't care about what we do but also have to fill their time sheets. The camera is on top of the laptop, you need to look interested and intrigued: ideal time to test some more options of earth:: a global map of wind and water.
Since there's no point in flying anywhere anymore (closed borders), let's enjoy exploring the famous west-east striking jet streams—the reason we fly the shortest way (over the pole) from Europe to North America but a longer way (along lower latitudes) back.
|Mode: Air, Height: 70hPa, Overlay: Wind, Projection: P (Patterson cylindrical projection introduced 2014)|
|Mode: Air, Height: 250hPa, Overlay: Wind, Projection: WB (Waterman Butterfly)|
A propos wind- and water-dispersed
A striking example of genetic invariance are Australian Nothofagaceae and their sister species from New Zealand. In 2012, Sauquet et al. published a dating analysis of Fagales with focus on this family to show the difference between several dating schemes. One was using ocean formation as age constraints. The ocean between Australia and New Zealand is middle-aged (on geological time scales) and Sauquet et al.'s set-up used a 55.8 Ma constraint for the divergence of the sister species on both sides (the same was used for the split of New Guinean and New Caledonian members of Trisyngyne (= Nothofagus subg. Brassospora; Heenan & Smissen 2013). Geotectonically it seemed possible (when you think plants behave like animals when it comes to reproduction), biologically and genetically the test was complete nonsense: in the data Sauquet et al. used, the antagonists from both sides of the oceans were near-identical (which was one reason their "safe" ingroup dating constraints gave much too old estimates for the outgroup, and "safe" outgroup constraints much too young estimates for the ingroup, but that's a different story).
|A visual depiction of intra-/intergeneric genetic difference between Nothofagaceae species based on data included in the study of Sauquet et al. (cyan – Nothofagus s.str., orange – its sister genus/subgenus Trisyngyne/Brassospora; green – genus/subgenus Lophozonia, dark yellow – genus/subgenus Fuscospora). See also: The most common errors regarding node dating)|
If their speciation, the Australian-NZ split (or New Guinea-New Caledonian split), was triggered by the formation of the ocean, the data showed they didn't evolve at all in over 50 million years.
Now, at least four of the five Nothofagaceae of New Zealand are wind- and/or water-dispersed and all are wind-pollinated. Let's check out the winds and water currents. Nothofagaceae species may have been separated by an ocean for 50+ million years but that doesn't mean they are not connected via wind or water (or have been until the recent past). The "Native Beech", as Nothofagaceae (lit.: the "false beech") are known in New Zealand, pollinates between September and December (PDF from allergy.org.nz, the NZ annual pollen calendar), it's probably not much different for their Australian sisters.
Here's the surface and above surface (850hPa) wind situation on e.g. Oct 7th, 2019.
|Mode: Air; Overlay: Wind; Date: 7/10/2019, 21:00 UTC|
And here's how it looked a month ago, near surface (1000 hPa, seeds are larger as pollen), i.e. towards the end of the fruiting season (November/February through April; see e.g. NZ Plant Conservation Network)
|Mode: Air; Overlay: Wind; Date: 5/3/2020 21:00 UTC|
And, just because it's nice, the waves and water currents at the same time (PS biological rafts are a real thing: plants can cross water floating with/on sea-debris).
There may be an middle-aged ocean of substantial width between Australia and New Zealand – these days 1700–2200 km stretch between false beech forests – but ample transportation means to cross it during any season (if you not have to rely on walking on dry land like most mammals).
That's by far not all...
...but enough for an Easter egg post. One last tip, next time the world is burning, Wuhan is not under lockdown anymore and the world's workbench is on full throttle again, or sand from the Sahara is raining down on you, check out earth:: a global map of wind and water with the following settings:
Mode: Particulates, Overlay: PM1.
Happy Easter and Earth watching everyone!