The difference between plant acclimation and plant adaptation is a key to understanding plant evolution. Acclimation is the way individual plants respond to drought, flooding or other changes in the weather or growing conditions. Adaptation is how groups of plants evolve over time to survive different environments. For gardens to prosper, you need to choose plants that are best adapted to your soil conditions, climate and ability to live in the shade or hot sun.
If you live in an arid area or where there are sudden plunges in temperature, you should consider plants that have a proven ability to acclimate themselves to your growing zone.
A gardener can often help plants acclimate themselves. An example of this is the hardening off of seedlings that would likely die if they were exposed to a sudden drop in temperature. The gardener moves the seedlings to a sheltered area for an hour or two in the early morning or late evenings, each day exposing them to longer periods of rain, wind and cold. Eventually, they will acclimate themselves to the new conditions and have a higher survival rate when they are finally planted.
Researchers develop hybrids of plants to adapt to many adverse conditions. Certain cultivars of citrus trees are better able to withstand frost. Some hybrid fruit trees have roots that are less susceptible to fungal rots, a problem in areas with heavy rainfall. Hybrid fruit trees have been developed to be self-pollinating where their ancestors were not. The result of hybrid cultivars is a far greater range of flowers, vegetables or fruit than would ordinarily be available to a gardener, plants that may be easier to care for or that may survive in an area of the country where they may not have thrived in decades prior.
Acclimation vs Adaptation
An individual plant can acclimate itself. It cannot adapt; plant adaptation requires multiple generations. The ability to acclimate is an adaptation. If the temperature suddenly plunges, acclimation can take place in hours or days.
You can help a plant acclimate itself by learning gardening tactics to help plants adjust. By better understanding the consequence of adaption, you can better choose cultivars that are appropriate for your climate, soil and space.
A species is a group of plants, for example Pigweed, that can produce viable offspring, meaning seedlings of Pigweed can grow into more Pigweed.
An ecotype is a population of one species of plant that can survive a certain kind of environment, different temperature, soil or available rainfall. An ecotype is a variety within a species.
For example, one ecotype of Pigweed, Amaranthus retroflexus, can survive the heat in North Carolina; another ecotype of Pigweed would die in the North Carolina heat but can endure the cold of Northern Canada.
A good way to understand how ecotypes relate to the gardener is to learn the growing zones of the United States Department of Agriculture. These zones are based on temperature, annual rainfall, altitude and a number of other environmental factors that are crucial to selecting the right kind of plants to grow.
The adaptation of different plant ecotypes is the result of speciation, the botanical process by which new species of plants arise. Suppose a river unexpectedly cut its way through a population of Prickly Pear cacti. One side of the river developed a moist climate; the other side got hotter and drier. Cacti on either side would acclimate themselves to the new conditions. Over time the cacti on either side of the river would adapt differently. Two different species would evolve.
The development of hybrids speeds this up. This has been done historically by selectively planting seeds of desirable plants. More recently it is being accomplished by manipulating DNA in plant cells. DNA passes plant characteristics from one generation to the next.
Species, subspecies, varieties
Hybrids are formed in the process of adaptation. Genes with qualities that enable a plant to survive can combine through genetic mutations or natural selection to form hybrids. The hybrid, a new variety of plant, can be called an ecotype or, given enough time and if it does not cross cross-pollinate with closely related species, it can be classified as a new species.
Genetic changes that occur lower than on the species level but are greater than a variety are called a subspecies.