Why is it best to include more than one type of trait when building a phylogenetic tree?

Question

I've got a test on friday and here is one of the questions on the study guide that I'm stuck on. Please Help!

Biologists can use a variety of different traits to make phylogenetic comparisons, including DNA sequences, morphological traits, behavior, and fossil evidence.
Why is it best to include more than one type of trait when building a phylogenetic tree?

Answer 1

How closely related would you think koala bears are to black bears? Or dolphins to tuna? Or raccoons to people, for that matter (they have manipulative hands, you know).

When dealing with phylogeny, you want to get things right. If you were to make a discovery in one field of science, you would want other fields to also agree with your findings. So too, you want all possible forms of natural evidence to agree to produce the strongest model of relationships possible.

If I think that one animal "A" is related to one animal "G," but only the fossil evidence suggests this, well... that might be OK, but it would be better if the genetic evidence were to suggest this independently and back up the original hypothesis. This makes for a much more robust model.

This is how science works. We make connections on the best evidence possible. When new evidence arises, this is added to the old evidence and the prevailing idea slowly changes for a more correct interpretation- whether by supporting or refuting previous interpretations.

Were I to propose that ducks were related to walnuts on the evidence that I find both near the shore of ponds... This might be accepted by some (stranger things have happened (see goose barnacles)) until it is found wanting by new evidence.

Evidence supported by more than one source is always preferred.

Answer 2

Including more than one type of trait helps biologists see strong relationships.

Think about it. If you only considered morphological traits, you would probably link fungus and plants as branches from a common ancestor, when gathered evidence actually suggests animals and fungus to be closer related. Also, fossil evidence alone might link the disappearance of the dinosaurs and the sudden explosion of mammals as some sort of great evolutionary shift. What I'm trying to show is that one type of trait can be rudimentarily useful when building a phylogenetic tree, but many pieces of evidence makes a stronger case. As an analogy, a strong court case is built upon testimony, DNA residues, fingerprints, eye-witness accounts, and other evidence; a weak one uses less.

I hope this helps!!

Answer 3

In biology, phylogenetics (Greek: phyle = tribe, race and genetikos = relative to beginning, from genesis = beginning) is the study of evolutionary relatedness between distinctive communities of organisms (e.g., species, populations). additionally time-commemorated as phylogenetic systematics, phylogenetics treats a species as a team of lineage-linked persons over the years. Phylogenetic taxonomy, that's an offshoot of, yet not a logical effect of, phylogenetic systematics, constitutes a means of classifying communities of organisms in accordance to degree of evolutionary relatedness. A phylogenetic tree, additionally stated as an evolutionary tree, is a tree showing the evolutionary interrelationships between distinctive species or different entities that are believed to have a elementary ancestor. In a phylogenetic tree, each and every node with descendants represents the main cutting-edge elementary ancestor of the descendants, with side lengths each and every so often resembling time estimates. each and every node in a phylogenetic tree is stated as a taxonomic unit. inner nodes are in many cases stated as Hypothetical Taxonomic contraptions (HTUs) as they'd't be rapidly noted. A phylogenetic trait is a trait that all and sundry, or maximum, species in a phylum reveal.

Answer 4

Nice academic exercise , but isn't DNA analysis making that somewhat obsolete? Anyway, to answer question , a single trait might be the result of convergent evolution.A whole list of common traits is less likely to be coincidence .