The relative lengths of the frog and mouse branches in the phylogenetic tree in Figure 26.13 ind

step 1 In this question, we're considering a phylogeny. And in the phylogeny, we have various creatures

The relative lengths of the frog and mouse branches in the...

Key Concepts

Phylogenetic Trees

Phylogenetic trees graphically represent the evolutionary relationships among species or genes. They are constructed using various data types, such as genetic sequences or morphological traits, to show common ancestry and divergence over time.

Branch Lengths

In phylogenetic trees, branch lengths often indicate the amount of evolutionary change that has occurred; longer branches suggest a higher degree of change or a faster rate of evolution, while shorter branches imply slower evolutionary change over the same period.

Rate of Evolution

The rate of evolution refers to the speed at which genetic or morphological changes accumulate in a lineage. By comparing branch lengths in a phylogenetic tree, one can infer which lineages have evolved more rapidly or more slowly, based on the extent of change observed in homologous traits.

Transcript

00:01 In this question, we're considering a phylogeny.

00:03 And in the phylogeny, we have various creatures, and i've highlighted the ones that are actually the most important that the actual question deals with.

00:12 So we have mouse down here at the bottom and a frog.

00:17 And we're actually asked to compare the mouse and the frog within this type ofilogyny.

00:22 I've also written drosophila, that is the fruit fly.

00:26 And i've written drosophila because that's what we're using as the out group or the anchor group.

00:34 Everything will be sort of in comparison to drosophila or it's sort of using the drosophila as the comparison as the reference.

00:47 So in the question, we're asked to look at the lengths of the lines that frog has versus that mouse is compared to in the phylogeny.

01:06 So in this phylogeny, the branches are different lengths and what does that mean? so we have to be really careful.

01:14 So phylogenies can really represent many different things.

01:20 And so it really depends on what that phylogeny was built for.

01:25 Was this phylogeny built to compare a mouse overall to a frog overall, the overall evolution of these two organisms? are we looking at a particular feature of a frog or a mouse, you know, like a physical characteristic? in fact, in this case, if you read the legend of the figure that we're supposed to be looking at, this phylogeny is comparing a particular genetic change within a particular gene.

02:09 So this is looking at sequences of homologous genes that play a role in.

02:16 And development.

02:18 And they're comparing those.

02:22 So it's comparing sequences of homelius genes that play a role in development.

03:08 And the legend of this particular figure states that the relative lengths of the bars for each organism represents the amount of change that has occurred.

03:22 Occurred in the gene.

03:25 So the lengths of the bars may send amount of genetic change in the genes.

04:11 So in that context, the amount of time that has passed, for instance, between in the amount of time that mice and, for instance, drosophila have diverged, there's been a lot more genetic change in drosophila because it's a much longer bar than what we see in mice, which is a much smaller bar.

04:41 So if we apply that same concept, frogs have a longer bar.

04:46 That means there's a lot more genetic change that has happened to these particular genes in frogs during that same amount of time as compared to to mice.

04:57 So there's been less genetic change in mice...

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