Plants range from simple seaweeds and single-celled birds to mosses, ferns and huge trees. Paleontologists like us debate exactly how these various shapes and sizes came to be, and whether plants evolved from algae into multicellular and three-dimensional forms in a gradual bloom or in one big explosion.
To answer this question, scientists turned to fossils. They concluded that some of the best-preserved specimens, such as trilobites, ammonites, and sea urchins, yielded some biological blueprints for the earliest periods in the group’s evolutionary history.
This led to the hypothesis that evolutionary lineages have a greater capacity to innovate early and stick to what they know after this initial flowering phase. This is true even for us: all different placental mammals evolved surprisingly quickly from a common ancestor. Does the same thing apply to the plant kingdom?
In our new study, we sought to answer this question by looking for specific traits in each major plant group. These features ranged from basic plant characteristics (the presence of roots, leaves, or flowers) to fine details that describe the variation and ornamentation of each pollen grain. In total, we collected data on 548 traits from more than 400 living and fossil plants; That’s more than 130,000 individual observations.
We then analyzed all of this data, grouped plants based on their overall similarities and differences, and mapped them all into what can be considered a “design space.” Because we know the evolutionary relationships between species, we can also predict the characteristics of their extinct common ancestors and incorporate these hypothetical ancestors into the design space.
For example, we will never find fossils of a flowering plant, but we know from its closest living descendants that this plant was bisexual, radially symmetrical, and had more than five spirally arranged carpels (the female reproductive part of the flower that contains the egg). . Data points from living species, fossils, and putative ancestors show how plant life has moved through the design space throughout evolutionary history and geological time.
We would expect flowering plants to dominate the design space, as they make up over 80% of plant species, but this is not the case. In fact, living bryozoans (bryophytes, liverworts, and hornworts) have almost identical body shapes.
This may not be entirely surprising, since the three bryophyte lineages go about their business three times longer than flowering plants. And despite their small nature, even ordinary mosses are quite complex and diverse when viewed under a microscope.
The evolutionary connections conveyed by the branching family tree in the above plot show that there is a structure generally intended to occupy the design space; As new groups emerged, they expanded into new territories. However, there is some evidence of convergence, as some groups, such as living gymnosperms (conifers and their relatives) and flowering plants, are more closely related than their common ancestors.
With all this, a certain difference between different groups in the field of design is clearly a result of extinction. This is clearly seen when we consider the distribution of fossil species (black dots) (colored dots) that are frequently seen among clusters of living species.
So how did the diversity of plant body plans evolve?
In general, a broad model is the gradual study of new structures that usually arise from reproductive innovations, such as the embryo, spore, seed, and flower. They offer evolutionary solutions to ecological problems faced by plants and are increasingly occupying drier and more complex niches on the earth’s surface. For example, the invention of seeds allowed the plants bearing them to reproduce even in the absence of water.
These expansions over geological time occur as episodic pulses associated with the emergence of reproductive innovations. The drivers of plant anatomical evolution are the combination of genomic potential and environmental opportunities.
Plant diversity suggests big bang was an impact
None of this is consistent with the expectation that evolutionary lineages begin as innovators before going extinct. Instead, the basic forms of plants appear to have arisen hierarchically throughout evolutionary history and developed the anatomical structure inherited from their ancestors. They have not lost their ability to innovate throughout their evolutionary lifetimes of billions or more years.
But are these plants different from the animals whose work provides the basis for the early evolutionary expectation of innovation and attrition? Not at all. Our comparative studies of animals and fungi show that when you examine these multicellular kingdoms in their entirety, they all exhibit a pattern of periodically increasing anatomical diversity. Individual lineages may soon become extinct, but overall kingdoms continue to innovate.
This suggests that there is a general pattern of evolutionary innovation in the multicellular kingdoms, and that there is still plenty of evolutionary fluid in the tanks of animals, fungi, and plants. Hopefully we’re still here to see what innovations come next. Source
Source: Port Altele
