How many offspring will a maple tree have?

Maple seeds/fruit

The maple seeds/fruit (known to botanists as samaras, and, in some cultures, as whirlybirds or helicopters), are usually abundant. There are a couple of dozen of them in this photo, which is of a small part, maybe 2 or 3 percent or less, of the whole tree.

How many of these would you expect to grow to be mature maple trees? And, more broadly, how many new adult trees would you expect this maple tree to have as offspring, during its life?

The answers to these questions may surprise you. They are none, and one. Why? Here's why. If each and every one of just the seeds in this photo grew to maturity, and other maple seeds did the same, and continued to do so for a few generations, the world would be covered in maple trees. It isn't. Unless there is an expansion of maples, each maple, on average, produces one offspring that reaches maturity and makes another generation's worth of maple seeds. On the other hand, if the replacement rate is less than one new maple per maple tree, it wouldn't take long for maples to vanish.

The usual replacement rate for organisms is one adult descendant in the next generation.

There are exceptions, but they must be temporary. Humans have often produced more than enough to replace themselves, and human populations have expanded. But this can't, and won't, go on forever. Other organisms have also had growing populations. Fire ants in the southeast US come to mind. There didn't used to be any, but now many a pasture has lots of nests visible. And, conversely, other types of living things have disappeared, or have nearly done so, such as cougars, because they don't replace their population numbers.

Darwin's concept of natural selection used the ideas of lots of offspring, and that the fittest survive. Although we can see no important differences between the maple seeds in the photo, it is likely that there are some genetic differences, giving some seeds a better chance than others. (Chance also plays a role -- where the seeds land surely would make a difference in their ability to survive.)

Keep growing and multiplying, but don't take over the earth's surface! Thanks for reading.

With Christ in the School of Prayer, by Andrew Murray, 44

This post continues a series of excerpts from With Christ in the School of Prayer, by Andrew Murray. I thank the Christian Classics Ethereal Library for making this public domain work available. To see their post of the book, go here. The previous post is here. As usual in this blog, long quotations are in this color.

And now, the lesson Jesus teaches us today in His school is this:  That the Father is just longing to give Him to us if we will but ask in the childlike dependence on what He says:
‘If ye know to give good gifts unto your children, HOW MUCH MORE shall your heavenly Father give the Holy Spirit to them that ask Him.’  In the words of God’s promise, ‘I will pour out my Spirit abundantly;’ and of His command, ‘Be ye filled with the Spirit’ we have the measure of what God is ready to give, and what we may obtain.  As God’s children, we have already received the Spirit.  But we still need to ask and pray for His special gifts and operations as we require them.  And not only this, but for Himself to take complete and entire possession; for His unceasing momentary guidance.  Just as the branch, already filled with the sap of the vine, is ever crying for the continued and increasing flow of that sap, that it may bring its fruit to perfection, so the believer, rejoicing in the possession of the Spirit, ever thirsts and cries for more.  And what the great Teacher would have us learn is, that nothing less than God’s promise and God’s command may be the measure of our expectation and our prayer; we must be filled abundantly.  He would have us ask this in the assurance that the wonderful HOW MUCH MORE of God’s Father-love is the pledge that, when we ask, we do most certainly receive. 

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