What Must a Species Have?
By Paul Tweed
The case of systems* and species.
*In this case we will define a system as a single strategy or a group of strategies which perform a task(s) which a species needs to survive.
Every living thing makes a living. This is true or the organism and its genes slip into extinction. Every individual organism tries to survive for a purpose, this may be only to accomplish the task of reproduction, or in the case of social creatures, to advance the cause of the colony so it may reproduce. Whatever the case, all organisms have to face the task of getting their genes into the next generation.
If we look at species as systems which over eons of time have developed through natural selection processes to survive in an environment we will find all species, whether plant or animal, elephant or protozoan, share common needs as living creatures on the planet earth.
If we refer to the study of species as a study of systems, (systems thinking says every system is part of a larger system and is also composed of subsystems itself) we can examine any living species in a similar manner. If you are new to systems, look at the following list of levels of organization in the study of living things and think of each as a unique system.
The preceding list illustrates how we can break the study of living things, (and non-living things) into categories or systems.
The Solar System
Earth - The Biosphere
For the most part, this is the area that biologists concentrate on.
Cellular Organelles (parts)
Protein, Carbohydrate, Fat (the macro-molecules)
DNA (the master-molecule)
Smaller molecules and simple compounds (Water, Salts, Acids etc..)
Atomic particles, (proton, neutron, electron)
If we consider all species a system, each must have ways to fit into the other systems they participate in. The rabbit must have a way to gain energy, avoid predators, and seek shelter and warmth. It also must be able to reproduce and get its genes into the next generation.
Following is a list of those generic subsystems essential to all species. It is a list which we can be currently comfortable with, but which certainly could be refined and improved upon over time. As with all science, this too may change.
- A species must have a subsystem to obtain energy. Since life itself is the process of maintaining low entropy in the face of the second law of thermodynamics. In other words, life is constantly fighting to keep itself together in the face of a world which would tear it apart if it did not have a constant input of energy to help it organize and stay together. No species exists without a subsystem to gain and use energy.
- A species must have a subsystem to resist being used for energy by other species. Life involves complex organic molecules that contain energy, and all life is therefor a potential energy resource for other species. Unless a species has subsystems to counter energy loss to higher trophic levels, (or decomposers) there will not be adequate survival of individuals and/or adequate energy available for reproduction.
- A species must have a subsystem to obtain and or conserve water. Because the chemical processes of life occur only in a water medium, an adequate supply of water must be maintained within an organisms body.
- A species must have a subsystem to reproduce a sufficient number of progeny (offspring) that will survive until that time at which they themselves (the offspring) reproduce. When a species reproduce sexually, which is the most common case, they must have subsystems that can bring the sexes together at the right time and place. For all species, there must be a subsystem to insure adequate survival of progeny (offspring).
- A species must have a subsystem to disperse offspring. Long-term survival of a species requires that the species be able to exploit resources that are discontinuous (in other words they need to get stuff that is not always in the same place all the time). All a species resources may not be located in time and space at an easily accessible location. Because of seasons, flower and fruiting times, migrations, etc, a species must have a way to disperse (spread out) its offspring to insure survival.
- A species must have subsystems to survive extremes in abiotic factors. The physical environment is variable, and extremes in such factors as temperature, wind, rainfall, fire, etc. are to be expected and must be survived.
Trade offs among species (systems)
Another important part of this systems approach to studying living things is the idea that species can redefine a potential problem as an opportunity. Some of the best examples of this lie in many species' use of some of their energy as a reward for services rendered by other species in solving one of the generic problems. There would be no insect, bird, or bat pollinators if the benefiting species of flowering plant did not invest some of its energy in nectar available to the appropriate pollinator. Many plants solve the problem of dispersing offspring by packaging seeds in palatable, (edible) energy packets, (seeds and fruits).
One generic problem not mentioned in the original list of six or so, is the need to possess the ability to modify the genetic blueprint, the need to combine different sets of genes to arrive at new, (different) offspring, and the need for mutation. Each species is the current best expression of thousands if not millions of years of development of successful strategies that work in an environment.
A problem that every species faces is that the rules (the physical and biological environment) keep changing. What works now may not work tomorrow. Therefore, the species as a group, (a population) over long periods of time (many generations) must have the ability to keep the subsystems that work and modify somehow those which need to fitted to the ever-changing environment. Thus, a species must have a way to adapt over time. Not individually, or even in one lifetime, but over the long haul, thousands or millions of years. For without this ability the species will become another which we wonder about as a fossil, an extinct system, not able to keep up in the diverse and changing nature of life on the planet earth.
Teacher notes Species as Systems: Introduction
- Develop with the students in an interactive way, (brainstorm) the idea of a species and the notion that being a successful species involves being able to solve certain general problems that must be solved by all species.
- Have the class generate and debate a list of general problems to be solved by all species.
- The list may or may not resemble the one from the article, whatever the class generates, let them keep it and weed out the ones which don't belong and perhaps discover some they missed later.
- Armed with their lists of problems for species to solve, the class can now pick some (a few) or even one local species for study. Any and all resources should be brought into play for this exercise.
Using the Species as a System Checklist
The included checklist is an example of the problems (areas of survival) all species must address through physiological, behavioral, or structural adaptation. Each of the items on the checklist can be used as an area for research. Check the example document included with this group of files.
For evaluation the students could choose from a variety of formats in the creative mode to present their findings.
- A written report
- A graphic display, with artwork, or collage
- Hypercard presentations
- Audio or video presentations.
- A speech or slide show
- Other relevant presentations.
- Something the student suggests
To evaluate the product of student's research simply apply the questions and problems to be solved by all species to the presentation.
One method for evaluating and encouraging the development of depth and understanding in these projects is to show the students a simple method which can be applied to their work.
These rubrics as they are sometimes called can help students in the preparation of their work. If the students know ahead of time the expectations for each level of the rubrics, they can make efforts to reach whatever level they desire.
- = did not complete work
- = Work done, simple answers to basic questions, poor organization, no elaboration.
- = Work done, answers to basic questions, good organization, some elaboration in a few areas
- = Work done, detailed answers to basic questions, very organized, elaboration in all areas
- = Work done, excellent organization, references cited, outstanding, detailed answers to basic questions, elaboration in all areas, new questions asked and answers purposed.
SPECIES AS SYSTEMS CHECKLIST
Subsystems and strategies
SPECIES AS SYSTEMS CHECKLIST- Example
- To obtain energy.
- To use energy
- To resist being used as energy.
- To obtain water (freshwater)
- To conserve water
- To reproduce
- To insure survival of enough offspring survive to reproduce.
- System to insure the sexes get together at the right time and place.
- To disperse offspring.
- To survive extremes in physical environment.
Subsystems and strategies Example Organism:
American Badger, Taxidea taxus jacksoni
- To obtain energy. Meat and eggs, fresh or decayed, and a small amount of vegetable matter. It digs for most of its prey. High percentage items include: ground squirrels, mice, and cottontail. It has been known to eat snakes, birds, and a variety of insects during times of low small mammal populations.
- To use energy Mammalian metabolic systems: The badger is a carnivore and obtains its energy by catching prey, it uses much of its energy digging burrows, hunting, searching for food, and a lesser amount of energy growing, replacing tissues, and reproducing.
- To resist being used as energy. Few wild animals will attack the Badger, it has few natural enemies. The badger is a wild fighter and has been known to take on and kill two hunting dogs in one fight. Humans are the chief predators of the badger. People kill the badger for many reasons, primarily connected to pest and predator control in agricultural areas.
- To obtain water (freshwater) The badger drinks very frequently.
- To conserve water. It uses the primary mammalian water conservation process of selective filtration of the blood by the kidneys. In times of plenty, the water is excreted in large amounts, in times of shortage the kidney recycles the water into the blood.
- To reproduce Little detail is known. Mating probably occurs late in August or September. There is a delay of at least 2 months for implantation. This allows the development to start around February and the birth from late April to early May. Approximately 8 months of active gestation, but it could be as short as 9 weeks. Litters usually consist of one to five young. Two to three being the normal number.
- To insure survival of enough offspring survive to reproduce. The young are born hairless and with eyes closed. At four weeks the eyes open The mother carries food to the young in an underground burrow and will protect the burrow with her life. The brooding chamber is a grass and herb-lined chamber some 24 to 30 inches in diameter placed 2 to 3 feet underground. By fall the young are hunting and taking care of themselves.
- System to insure the sexes get together at the right time and place. Not really known.
- To disperse offspring. The young leave the burrow at about 8 to 10 weeks old and set out to develop their own territory. The Adults will keep the young out of the old home territory.
- To survive extremes in physical environment. The badger is covered with a thick coat of coarse fur. Etc.. Etc.. Etc.........
I think you can see the type of things a student could find. Now try it for a plant. Or an insect.