So, as zoologists using maximum parsimony, we'd choose the phylogeny that shows feathers evolving once.

所以，当动物学家使用最大简约法时，我们选择羽毛只进化次进化树。

Here is a phylogeny of the land plants that are alive today.

这是现存陆地植物系统发育图。

Jessica Green is co-founder of phylogeny that is building a microbial map of the world.

杰西卡·格林是名为" 系统发育" 组织联合创始人，该组织正在绘制生物世界地图。

So zoologists will often make several phylogenies using different approaches.

所以，动物学家通常会使用不方法来立进化树。

Phylogenies are complicated because they're tracking many different traits, animals, and time all at once.

立进化树很复杂，因为它们时追踪许多不征、动物和时间。

But by making phylogenies and examining DNA, we do know they're the closest non-animal relative we've got.

但是通过系统发育和 DNA 检测，我们至少知道它们是我们最亲近非动物亲戚了。

In a phylogeny, individual species or groups of species sit at the tips of the tree.

在进化树中，单个物种或组物种群位于树顶端。

There are many organisms out there whose phylogeny is a total mystery to us.

那里有许多生物，它们系统发育对我们来说完全是个谜。

Using the maximum likelihood approach, we'd end up with a phylogeny where the sequence of events has the highest probability.

使用最大似然方法，我们可以得出序列事件在进化树有最高可能性。

So, let's go to the phylogeny.

因此，接下来让我们看看进化树。

Keeping track of who's related to who can get messy, so we study animal relationships using a diagram called a phylogeny or a phylogenetic tree.

记录谁与谁是有关系会变得很混乱，因此我们利用个图示来研究物关系，那就是系统发生树，或进化树。

To actually build our clades, the simplest approach is to go for maximum parsimony, where the phylogeny with the fewest number of gains or losses of a trait wins.

要真正构我们进化枝，最简单方法是使用最大简约法，根据个性状得或失，用最少数字，来构进化树。

And they can rotate around their nodes, so this phylogeny, this phylogeny, and even this phylogeny are exactly the same.

它们还会变换节点，因此，这个进化树，和这个进化树都是个进化树。

If we keep getting the same answer, we know our phylogeny is a good guess for how different animals are related to each other.

如果我们直得到相答案，我们知道这次进化树对于不动物是如何相互联系猜测是合理。

And, in this tree, time moves from the root of the tree to the tips of the branches, meaning that branches towards the bottom of the phylogeny diverged before the branches at the top.

在这棵树上，时间从树根向树枝顶端移动，这意味着系统发育底部树枝比顶部树枝先分化。

There's no best way to make a phylogeny, and one phylogeny is really just a hypothesis for all the evolutionary relationships between species or clades based on specific traits or groups of traits.

没有最好方法来立进化树，棵进化树也只是个假设而已，根据具体性状或广泛性状来对所有种群和进化枝之间进化关系做假设。

So using observations and the molecular clock approach, we can decide which traits will help us group animals into clades, or a group with all the descendants of the same common ancestor, and fit those clades together into a phylogeny.

因此，通过观察和分子钟方法，我们可以决定哪些征可以帮助我们归类动物到进化枝，或者把所有共祖先后代归为类，这些进化枝就这样集合在起形成进化树了。