BIO 202 — Lesson 23

A

A clade of species, 200 birds each. Now and then a barrier cuts a small piece, 10 birds, off a species. A piece that stays apart 40 generations is a new species; one that meets its species, and whose birds mate across, rejoins it. See how a choosiness allele fares inside each species, and across the clade.
A choosy female mates less often with a male whose colour is unlike the one she likes, as in lesson 21; a piece's colour drifts away from its species' while it is apart. Cost of choosiness, the red arrow: a choosy bird leaves fewer young. Preference strength, the arrow onto the colour gap: how much a choosy female avoids a male of the other colour.

The cladeClade 1 of the 16 that Go plays. Each line a species, from the generation it split off its parent (the short grey stroke); its shade, its share of the choosy allele: light few, dark many (one hue). ×: a species lost.Run 1, at the generation the plots have reached.

over timeThe 16 clades, each thin; their average thick.Choosy alleles, the clade's share: the share of choosy alleles in each living species, averaged over the species (each counted once). Species living: how many. Between species, added up: the first part of the change below, alone.

The change in the clade's share, taken apart since generation 0Every 50 generations the change in the clade's share of the choosy allele (each living species counted once) is taken apart, as lesson 13 took a change apart, with species in place of birds; added up since generation 0 and averaged over the 16 clades.Between species: how a species' share goes with the living species it leaves 50 generations on (itself counted): species that split more and are lost less count more. Inside species: each species' own change, birds breeding generation by generation. At the splits: a new species' share against its parent's on the day they split.They add up exactly to the black line.

Genes, birds, speciesChoosiness gene: a choosy and a take-any allele. Cost of choosiness, the red arrow: how many fewer young a choosy bird leaves, as a share (two choosy alleles; one, about half).Colour gap: how far a cut-off piece's colour has drifted from its species'. Each generation the piece meets its species with chance 1 in 20; the birds mate across, and the piece rejoins, less often the bigger the gap, the more of them choosy, and the stronger the preference: preference strength, the arrow onto colour gap → rejoins (dashed at 0: a choosy female takes any male).A piece apart 40 generations is a new species. Grey arrows: fixed.

TargetOne species of 200 birds at the start, half its alleles choosy. Go plays 1,000 generations, 16 clades.The picture: what a hit looks like; the red box, where the thick line, the 16 clades' average, should end.

practice

To finish

Hit the two targets. 0 of 2

R code

B

The same clade. The trait now is dispersal: a disperser leaves more young, and dispersers cross barriers, so a cut-off piece can meet its species and rejoin it. See the disperser allele inside each species, and across the clade.
Advantage, the arrow to a bird's young: how many more young a disperser leaves. How far dispersers go, the arrow to a piece rejoining.

The cladeClade 1 of the 16 that Go plays. Each line a species, from the generation it split off its parent (the short grey stroke); its shade, its share of the disperser allele: light few, dark many (one hue). ×: a species lost.Run 1, at the generation the plots have reached.

over timeThe 16 clades, each thin; their average thick.Dispersers, the clade's share: the share of disperser alleles in each living species, averaged over the species (each counted once). Species living: how many. Between species, added up: the first part of the change below, alone.

The change in the clade's share, taken apart since generation 0Every 50 generations the change in the clade's share of the disperser allele (each living species counted once) is taken apart, as lesson 13 took a change apart, with species in place of birds; added up since generation 0 and averaged over the 16 clades.Between species: how a species' share goes with the living species it leaves 50 generations on (itself counted): species that split more and are lost less count more. Inside species: each species' own change, birds breeding generation by generation. At the splits: a new species' share against its parent's on the day they split.They add up exactly to the black line.

Genes, birds, speciesDispersal gene: a disperser and a stay-home allele. Advantage, the arrow to a bird's young: how many more young a disperser leaves, as a share.How far dispersers go, the arrow to the piece rejoining: each generation dispersers cross a barrier, and a cut-off piece rejoins its species, with that chance times the two's average share of dispersers.A piece apart 40 generations is a new species. Every species is lost with the same small chance, 1 in 500 a generation. Grey arrows: fixed.

TargetOne species of 200 birds at the start, half its alleles dispersers. Go plays 1,000 generations, 16 clades.The picture: what a hit looks like; the red box, where the thick line, the 16 clades' average, should end.

practice

To finish

Hit the two targets. 0 of 2

R code

C

B's clade, with losses that depend on the species: a species whose birds stay home has a narrow range and is lost more often; a species of dispersers has a broad range and is lost less. See which wins across the clade, fewer splits or fewer losses.
Losses, the red arrow from a species' range: how often a species with no dispersers is lost each generation.

The cladeClade 1 of the 16 that Go plays. Each line a species, from the generation it split off its parent (the short grey stroke); its shade, its share of the disperser allele: light few, dark many (one hue). ×: a species lost.Run 1, at the generation the plots have reached.

over timeThe 16 clades, each thin; their average thick.Dispersers, the clade's share: the share of disperser alleles in each living species, averaged over the species (each counted once). Species living: how many. Between species, added up: the first part of the change below, alone.

The change in the clade's share, taken apart since generation 0Every 50 generations the change in the clade's share of the disperser allele (each living species counted once) is taken apart, as lesson 13 took a change apart, with species in place of birds; added up since generation 0 and averaged over the 16 clades.Between species: how a species' share goes with the living species it leaves 50 generations on (itself counted): species that split more and are lost less count more. Inside species: each species' own change, birds breeding generation by generation. At the splits: a new species' share against its parent's on the day they split.They add up exactly to the black line.

Genes, birds, speciesB's diagram, advantage and how far dispersers go held.Its range: a species' share of dispersers. Losses, the red arrow: each generation a species is lost with chance (losses) × (its share of birds that stay home): a species of stay-at-homes at the full rate, a species of dispersers never. The clade's last species is never lost. Grey arrows: fixed.

TargetOne species of 200 birds at the start, half its alleles dispersers. Go plays 1,000 generations, 16 clades.The picture: what a hit looks like; the red box, where the thick line, the 16 clades' average, should end.

practice

To finish

Hit the target. 0 of 1

R code

A

The cladeClade 1 of the 16 that Go plays. Each line a species, from the generation it split off its parent (the short grey stroke); its shade, its share of the choosy allele: light few, dark many (one hue). ×: a species lost.Run 1, at the generation the plots have reached.

TargetOne species of 200 birds at the start, half its alleles choosy. Go plays 1,000 generations, 16 clades.The picture: what a hit looks like; the red box, where the thick line, the 16 clades' average, should end.

To finish

B

The cladeClade 1 of the 16 that Go plays. Each line a species, from the generation it split off its parent (the short grey stroke); its shade, its share of the disperser allele: light few, dark many (one hue). ×: a species lost.Run 1, at the generation the plots have reached.

TargetOne species of 200 birds at the start, half its alleles dispersers. Go plays 1,000 generations, 16 clades.The picture: what a hit looks like; the red box, where the thick line, the 16 clades' average, should end.

To finish

C

The cladeClade 1 of the 16 that Go plays. Each line a species, from the generation it split off its parent (the short grey stroke); its shade, its share of the disperser allele: light few, dark many (one hue). ×: a species lost.Run 1, at the generation the plots have reached.

TargetOne species of 200 birds at the start, half its alleles dispersers. Go plays 1,000 generations, 16 clades.The picture: what a hit looks like; the red box, where the thick line, the 16 clades' average, should end.

To finish

Good job!