Botany: what is the evolutionary significance of losing a cotyledon?

In summary, the conversation discusses the evolutionary relationship between angiosperms and the number of cotyledons they have. It is believed that ancestors of angiosperms originally had two cotyledons, but the loss of one led to the rise of monocots. However, the benefits of having one cotyledon over two are not known. Modern monocots and dicots have distinct characteristics, and it is believed that the divergence between the two occurred about 200 million years ago. As for the environment, both monocots and dicots prefer warm and loose topsoil for germination.
  • #1
Arctangent
15
0
Hey there,

I was reading up on angiosperms, and one of the possible evolutionary relationships that showed up were ancestors that originally had 2 cotyledons, and the lost of one later on rose to the arisal of monocots.

I suppose this might be a really tough question, but what would be the benefit for a plant to start with having one cotyledon as opposed to two?

Or maybe it'd be better to ask: what kind of environment would be better for a germinating seedling that has only one cotyledon?
 
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  • #2
Arctangent said:
I was reading up on angiosperms, and one of the possible evolutionary relationships that showed up were ancestors that originally had 2 cotyledons, and the lost of one later on rose to the arisal of monocots.
That's interesting, I had not heard of that relationship before. I am curious where did you read that?
what would be the benefit for a plant to start with having one cotyledon as opposed to two?
Can't say I know of any benefits of having one seed leave over two.
Modern monocots and dicots do have very distinctive characteristics: monocot(e.g. major leaf veins parallel, flower parts in multiples of three, stem-vascular-bundles scattered, pollen with a single pore...) dicot [e.g. major leaf veins reticulated (netted), flower parts in multiples of four or five, stem-vascular-bundles in a ring, pollen with 3 pores]. Those are just a few morphological differences (reference). Scientists believe the monocot-dicot divergence from a common ancestor, occurred about 200 MYA (million years ago). That would be sufficient time to evolved all those differences we see today.
what kind of environment would be better for a germinating seedling that has only one cotyledon?
I don't know what environments would be more advantangeous to monocots. Both mono and dicots prefer warm, loose friable topsoil to enhance germination.
 
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  • #3


The loss of a cotyledon in plants is a significant evolutionary event that has led to the diversification of plant species. The cotyledon is the first leaf or pair of leaves that emerge from a germinating seed, and it plays a crucial role in providing nutrients to the developing plant embryo. In angiosperms, or flowering plants, there are two types of cotyledons: dicots, which have two cotyledons, and monocots, which have only one cotyledon. The loss of a cotyledon in monocots is believed to have occurred as a result of natural selection and adaptation to specific environmental conditions.

One possible benefit of having only one cotyledon is that it allows for a more efficient use of resources. By having only one cotyledon, the plant can focus its energy and nutrients on producing a larger and more robust single leaf, rather than two smaller ones. This may be advantageous in environments where resources are limited, such as in areas with poor soil quality or in areas prone to drought. Additionally, having only one cotyledon may also allow for a faster germination and growth rate, giving the plant a competitive advantage in these environments.

Another potential benefit of losing a cotyledon is that it allows for the development of specialized structures and adaptations. Monocots have evolved to have unique vascular systems, root structures, and flower arrangements that are not found in dicots. These adaptations may have been facilitated by the loss of a cotyledon, as it allowed for a redirection of resources towards the development of these specialized structures. This diversification of plant species has led to the success and abundance of monocots in various habitats.

In conclusion, the loss of a cotyledon in plants has played a significant role in their evolutionary history. It has allowed for the diversification of plant species and the development of specialized adaptations, making them better suited to thrive in different environments. By understanding the evolutionary significance of this event, we can gain a deeper appreciation for the incredible diversity and adaptability of plants.
 

What is a cotyledon in botany?

A cotyledon is a leaf-like structure found in the embryo of a seed. It serves as a food source for the developing plant until it can produce its own food through photosynthesis.

Why do some plants lose their cotyledon?

Plants can lose their cotyledon due to evolutionary adaptations. In some species, the cotyledon is no longer needed as the plant has evolved to obtain its food through other means, such as by absorbing nutrients from the soil or through symbiotic relationships with other organisms.

What is the evolutionary significance of losing a cotyledon?

The loss of a cotyledon allows plants to allocate their resources more efficiently. By not having to produce and maintain a large cotyledon, the plant can invest its energy into other structures, such as leaves, roots, or flowers, that are more important for its survival and reproduction.

Do all plants lose their cotyledon?

No, not all plants lose their cotyledon. Some species still rely on their cotyledon for survival and are not able to produce their own food until the cotyledon withers away.

Can a plant survive without a cotyledon?

Yes, a plant can survive without a cotyledon as long as it has other means of obtaining food and nutrients. However, the loss of a cotyledon may affect the plant's growth and development, and in some cases, can make the plant more vulnerable to environmental stressors.

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