Gene Flow

“A seed crosses a valley carrying more than matter: it moves variants between populations.”

01 / PLAINLY

What it means, plainly

When organisms or gametes move and reproduce, they can exchange alleles between populations.

02 / CONTEXT

A little more

Gene flow moves genetic variants between populations through migration and reproduction. It can add local diversity, make populations more alike, or introduce alleles that selection favors or removes in the new environment.

03 / WHY IT MATTERS

Why it matters

It links ecology with evolution: roads, corridors, winds, and isolation change which genes cross a landscape.

04 / EXAMPLE

A familiar example

Pollen carried into another meadow may introduce a flower-color variant that its population had never contained.

05 / LIMIT

What it does not mean

Movement alone is not enough: an organism or gamete must contribute genes to the receiving population for gene flow to occur.

06 / NOTICE

Notice it in your day

Sketch two separated populations and add one route for pollen, seeds, or mates. Mark which barriers would truly stop exchange.

FINAL NOTE

The idea worth keeping

Separate physical movement from successful reproduction, then ask whether exchange homogenizes or diversifies populations.

QUESTIONS / 02

Questions people still have

Does gene flow always increase diversity?

It may raise diversity within one population while reducing differences among populations by mixing their allele frequencies.

Can gene flow oppose local adaptation?

Yes. A steady arrival of alleles suited elsewhere can slow differentiation favored by local conditions.