BIO 202 — Lesson 21

Clade 1One species at generation 0, and every species descended from it: a line a species, from the generation it began to the generation it was lost or the present. A new species branches off its parent.Shade: the share of a species' fish that carry the disperser allele. Light, few dispersers; dark, many.Clade 1 of the 16 that Go plays.

Over time:The clade's average: each living species' share of dispersers, every species counted once, averaged. Thin lines: each of the 16 clades; thick: their average.The shaded cloud (round 3): where the average of 16 clades could fall, from resampling these 16 with replacement (Lesson 2), the middle 90%.Inside the species of clade 1: each species' own share, a thin line for each.

The clade's change, taken apartEvery 50 generations the change in the clade's average splits into three parts that add up to it exactly (Price's equation, one level up: species in place of fish). Added up since generation 0, and averaged over the 16 clades.Between species: species with more dispersers leave more species, or fewer (the covariance of a species' share with the number of species it leaves).Inside species: the change in each species' own share as its fish live and breed.At the splits: how a new species' share differs from its parent's when it begins.

TargetA species: 200 fish. A fish carries the disperser allele or not. A disperser leaves more young than a fish without it, by the advantage you set.Now and then a barrier cuts a piece off a species (10 fish). Each generation it stays cut off, dispersers from either side cross it with a chance that grows with how many there are and how far they go: the piece rejoins. A piece cut off for 40 generations is a new species (Lesson 19 C).Each species is lost with chance 0.002 a generation, whatever it carries; at most 40 species. Go plays 1000 generations in 16 clades.

advantage to a disperserHow many more young a disperser leaves than a fish without the allele, in its own species: 0.01 is one percent more.

how far dispersers goThe chance, each generation, that dispersers cross a barrier into a cut-off piece, when every fish is a disperser.

practice — a run with this ticked does not count

Your runsEach run a mark at its advantage (across) and how far dispersers go (up). ▲ the clade's average rose; ▼ it fell. Bigger: by more.

Sister cladesEvery split in the 16 clades with living species on both sides now: a dot, in a column by how the new species started: with fewer dispersers than its parent, about the same, or more (0.05 either way).Up: the living species on the new species' side now, minus those on its parent's side. The bar: each column's average.

To finish

Hit the two targets, then draw the third. 0 of 3

R code

Your runsEach run a mark at its advantage (across) and how far dispersers go (up). ▲ the clade's average rose; ▼ it fell. Bigger: by more.

To finish

Good job!