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Course: Middle school biology - NGSS > Unit 8
Lesson 1: Evolution and common ancestryCommon ancestry and evolutionary trees
Review your understanding of common ancestry and evolutionary trees in this free article aligned to NGSS standards.
Key points
- Each modern species has a series of ancestral species stretching back through time. This series of ancestors is a species’ evolutionary lineage.
- A common ancestor is an ancestral group of organisms that is shared by multiple lineages. For example, an early mammal species, which existed sometime in the distant past, is a common ancestor of whales, cats, humans, and all other modern mammals.
- An evolutionary tree models the relationships between different lineages and their common ancestors.
- Evolutionary trees have a branching pattern. The tips of the branches represent modern groups of organisms. The branch points, or places where the branches split, represent common ancestors that existed in the past.
- Species that share a common ancestor in the more recent past are more closely related. Species that share a common ancestor in the more distant past are less closely related.
Want to join the conversation?
- What would it look like if there is a common ancestor between A and B only?(12 votes)
- I think you are going to have to imagine that species C didn't even exist, just to see what it would look like with just A and B.(18 votes)
- Is it just me or like the whole lesson all i could think about was Pokemon and the evolutions(13 votes)
- Ahahahahaha I can totally see that, but now all I can think of is, "Pika, Pika!"(5 votes)
- *(joke)*
why did the dinosaur cross the road?
I'll give you the answer....
DA CHICKEN WASNT INVENTED YET(11 votes)- hahahha i gotta admit that one was funny(1 vote)
- how can they be close totgher(5 votes)
- When they are saying they are close together they don’t mean that they are the exact same species, what they mean is that they have common ancestors, so they may be more closely related than if they weren’t from common ancestors(7 votes)
- In the example of the branch points, who is the most closely related: A, B, or C?(5 votes)
- I wonder if scientist made a evolutionarily tree for every thing that has existed in the world.(4 votes)
- Scientists have not made a evolutinary (or tree of life) that has every living thing in it. But there is a 'tree of life' that holds 2.3 million species in the world, sadly thats nowhere near the amount of animals in the world.(4 votes)
- how is a car made?
what is electricity?
how was the first human made?
what is the name of the first dog?
how does the water cycle work?
how did god make the whole world?(4 votes)- The first dog wouldn't have a name because it was created before humans started naming themselves, or maybe even humans themselves(1 vote)
- What can stop there from being another species?(3 votes)
- Several factors can prevent the emergence of a new species. One of the most significant factors is the availability of resources. If a particular area is already occupied by a well-adapted species, it may be difficult for a new species to establish itself and survive. Additionally, competition from other species can also pose a challenge to the emergence of a new species. Other factors such as environmental changes, genetic mutations, and natural disasters can also have an impact on the evolution of new species. Ultimately, the emergence of a new species is a complex and unpredictable process that is influenced by a variety of factors.(2 votes)
- Is there any diseases that can make other species(2 votes)
- From time to time viruses cross the host‐range barrier expanding their host range. However, in very rare cases cross‐species transfer is followed by the establishment and persistence of a virus in the new host species, which may result in disease.(3 votes)
- I'm still confused as to what a lineage is.(2 votes)