More Than Training, My View

Communication is the transmission of information from one individual to another, which is designed to influence the behavior of the receiver. In a simple communication system, a source encodes and transmits a signal, which is detected by a receiver, and decoded into meaningful terms. The effectiveness of animal signals is influenced by the physical environment, the nature of the receiver, and the influence of other signallers. Different sensory modalities are best suited to different habitats. Much depends, therefore, upon the physical nature of the habitat (McFarland, 2006) 

Animal signals are “behavioral, physiological, or morphological characteristics fashioned or maintained by natural selection because they convey information to the other organisms” (Otte, 1974, p.385).

In the complexity of human language, the prototypic units are specific sounds, sound categories, and sound combinations. But, certain human languages consist of gestural units rather than phonological units, and it is sufficiently flexible to permit other types of units as well. 

Phonetic syntax exists in animal languages (Cleveland & Snowdon, 1982), but compared with the human phonological system than the human syntactic system. Lexical syntax has also been observed in natural animal languages (Cleveland & Snowdon, 1982; Robinson, 1984), albeit in a much more limited sense than in human languages. 

So, we can conclude the need for communicating clearly and precisely in interspecific communications.

The Basic Learning Principles

Before continuing, let me state that I’m not evaluating or judging the working methods of any professional. We are free to decide which kind of relationship we want to create with the other species. My approach is not better or worst than any other. My actual work is the result of almost two decades of practical experience with regular updates based on my scientific and empirical knowledge and my technical and ethical limits. My mentors taught me, and now I talk to my students and colleagues, that we are permanent students, that we should always look for more with critical thinking and the humility that we will never know everything.

It all starts with the terms and signals we use. We need to scientifically define them, according to some behavior modification principles:

  • Signal: “A signal is everything that intentionally causes a change in the behavior of the receiver” (Abrantes, 2013). “A signal is defined as a character which has involved in order to transmit information to other individuals” (Zahavi 1987, p.306). To communicate with other species, we use signals.

  • Cue: A cue is everything that unintentionally causes a change in the behavior of the receiver (Abrantes, 2013).

  • Command: A command is a signal that changes the behavior of the receiver in a specific way with no variation or only extremely minor variations (Abrantes 2013).

  • All signals have a meaning and a form.

  • We classify the signals on a scale from Good to Bad, depending on its efficiency, clarity, intensity, form and unequivocal understanding of the receiver, regardless of the environment.

  • A signal will cause a behavior, ergo:

A signal => A behavior.

  • All behavior has a consequence, ergo:

A signal => A behavior => A consequence

  • The consequences will define the frequency, intensity and/or duration of a behavior. Reinforcers and inhibitors are used for.

  • Reinforcer: A reinforcer is anything that increases the frequency, intensity, topography, and/or duration of a particular behavior, when presented (+) or removed (-) simultaneously or immediately after a behavior takes place.

Note: The correct term is reinforcer, not reward: “The strengthening effect is missed, by the way, when reinforcers are called rewards. People are rewarded, but behavior is reinforced. If, as you walk along the street, you look down and find some money, and if money is reinforcing, you will tend to look down again for some time, but we should not say that you were rewarded for looking down. As the history of the word shows, reward implies compensation, something that offsets a sacrifice or loss, if only the expenditure of effort. We give heroes medals, students degrees, and famous people prizes, but those rewards are not directly contingent on what they have done, and it is generally felt that the rewards would not be deserved if they had been worked for.” (Skinner, 1986, p. 569).

Note 2: I have heard some claims about the neuroscience perspective, that writes about “reward learning”. Although we all have the right to choose how we want to approach the subject, it is important to know that when we are modifying behaviors, we are using “behaviorism”, not neuroscience. If so, please have the kindness to send me which neuroscience techniques are used for it.

Note 3: I don’t understand the current rejection of behaviorism or the behavior itself. Has this approach become less lucrative or trendy? Although we all have the right to choose how we want to approach the subject, it is essential to know that, as I said above, when we are modifying behaviors, we are using “behaviorism” that is not only limited to Skinner or Pavlov. There are several theories of learning, which the major are: Functionalistic (Thorndike, Skinner, Hull), Associationistic (Pavlov, Guthrie, Estes), Cognitive (Gestalt theory, Piaget, Tolman, Bandura), Neurophysiological (Hebb) and Evolutionary (Bolles).

  • Inhibitor: An inhibitor is anything that decreases the frequency, intensity, topography, and/or duration of a particular behavior, when presented (+) or removed (-) simultaneously or immediately after a behavior takes place.

Note: Resulting from all his linguistic experience throughout the world, Dr. Roger Abrantes (2013) suggested the use of the word “inhibitor” rather than “punishment” in his book “The 20 Principles All Animal Trainers Should Know”. When translated directly from the English to the other languages, especially Latin languages, “punishment” also has religious connotations.

Note 2: This can sound a bit of contradiction with the rewards/reinforcer term. Not exactly. As a Latin language origin speaker, I understand and agree with the “inhibitor” term, since “punishment” has a punitive/aggressive meaning, and some religious connotation when translated. Inhibitors not. They are described in behaviorism (e.g: Pavlovian Conditioned Inhibition) with a similar meaning as “punishment” in the Skinnerian view. The same doesn’t happen with “reinforcer” and “reward” when translated.

  • Reinforcers and inhibitors are conditionals, which means, they are always subjected to three distinct conditions: (1) the individual, (2) the behavior, (3) the moment.

  • There are four ways to increase an aspect of a behavior: (1) reinforce the behavior, (2) do not inhibit the behavior, (3) create opportunities to show the behavior, (4) do not reinforce a behavior that is incompatible with behavior you want.

  • There are four ways to decrease an aspect of a behavior: (1) inhibit the behavior, (2) do not reinforce the behavior (extinction), (3) prevent opportunities to show the behavior (forgetting), (4) reinforce a behavior that is incompatible with the behavior you want.

  • An aversive causes avoidance of something, a situation or behavior through the use of an unpleasant stimulus. Therefore, any kind of material or technique can be aversive as long as it causes discomfort or avoidance to the individual.

Note: I defend that all training based on fear or intimidation, should be considered, by definition, “coercive training” or “coercive behavior (from the trainer)” rather than “aversive.”

Note 2: By definition, all animal trainers use reinforcers and inhibitors and aversives, since we cannot control 100% the environment and it is the receptor (dog, horse, etc.) that will say if the consequence is a reinforcer or inhibitor in the present conditions. Training based on 100% reinforcements or 100% inhibitors is something technically impossible, biologically unnatural (relation of the costs x benefits of the organisms and ESS) and a mistake to all who believe it and can make with it slogans, marketing campaigns or using argumentum ad verecundiam. That’s a fact that all behavioral science students know, even if they don’t admit it or using other words to describe it. But that’s not the question here. The subject here it’s about choices and how we want to have a relationship with (our own and) other species. The way I communicate with other species, I will show below. This way, it is my choice.

Note 3: About some studies and training techniques:

1- A study doesn’t prove anything. Science is a process, not a conclusion. A study shows a result based on the hypothesis and methods used in a specific situation, which creates more questions for further studies. We should be careful with the language used when promoting them.

2- All the papers I’ve researched, and I invite you to do the same, I never found the qualifications or experience of the trainers (very important for a study, since everyone can say that is a trainer), and an individual observation of the dog’s daily environment, their routines, etc. Some of the studies have a lack of this information, are based on the owner’s opinion, observation in a close study place (comparative psychology), or in environments with previous associations.

3- Concluding the previous note, it is my opinion that labeling, classifying or using unclear definitions (or popular ones) about training methods in a study is a dangerous and biased path that invalidates it from its hypothesis.

Note 4: You can read my article about materials and training techniques. Click here.

Learning and emotions

I’m seeing a current (and increasing) trend stating that “fear is an emotion and emotions are not reinforced.” There are also few mentions about classical conditioning that “doesn’t reinforce nothing.” When I look for its references, I just found popular articles with a few allusions to neuroscience and the amygdala function, with a very passionate speech, in my opinion.

This trend is being used even by academic experts and in professional courses as (another) an “absolute truth.” This “of course theory” worries me much more about the level of limitation for individual thinking and questioning that creates, and how the science is being placed in a place that didn’t reach yet. 

I’ll give you basic neuroscience and behaviouristic perspective about the emotions. You can find all the references at the bottom of this article.

I don’t have “a point” about this subject. I’m full of questions, not certainties. But one thing I’m sure: There is a lot of misinformation and misunderstanding related to these subjects. So, I recommend you to search about it with critical thinking, questioning all professionals about academic references, and making some of the questions below. In the end, make your choice in which speech fits better for you. 


  • Emotions are internal brain states that cause observable external changes in behavior; observable internal physiological changes in the state of the body; changes in other mental states; and, under some conditions and in some species, changes in that we are consciously aware of.

  • Emotional states are generated by spatially and temporally characteristic patterns of neuronal (electrical) activity in the brain, together with associated changes in brain chemistry (hormones, neuromodulators, and such).

  • All mammal brains are constructed with the same basic design: brain stem, limbic system, cerebellum, and cerebral cortex. 

  • The major difference between the brains of people and animals is in the size and complexity of the cortex. 

  • Emotions can be inferred from several kinds of data. All of these measures are parts of the science of emotion.

  • Emotions are experienced and expressed at three different levels: (1) the psychological level, (2) the neurophysiological level, and (3) the behavioral level.

  • A number of researchers in the emotion area have adopted classification systems for emotions that suggest that there are typological differences, including hierarchical organization, for different kinds of emotions. The nature of the criterion varies between researchers. There is no scientific consensus about it.

  • The modern neuroscience supports Darwin’s view on central emotion states in animals.

  • An emotional state is composed of the observation of behavior, neuroscience measures, conscious experience and psychophysiology/endocrine measures.

  • The functional state of emotion follows the sequence Stimuli -> Context -> Central Emotion State -> Observed Behavior, Somatic responses (both connected with the stimuli), Subjective Reports, Psychophysiology, and cognitive changes.

  • The neuroscientist Joseph Le-Doux (2012) suggested the “MAD” (Motivation, Arousal, and Drive) theory as a replacement of Darwin’s Central emotion state, classifying the emotions as subjective experiences.

Emotions and feelings:

  • Emotions and feelings are not the same things, although they are closely related. While emotions are functional states, feelings (or affects) emphasizes conscious experiences of something happening in one’s internal own body (feel tired or thirsty).

  • “Emotion has subjective, physiological, and behavioral manifestations that are difficult to reconcile with each other. An emotion is a private experience. There is no way we can know the emotional experiences of another person. We tend to assume they are the same as ours, but we have no experimentally conclusive or logical way of verifying this. In scientific terms, we cannot assume that animals have particular subjective feelings any more than we are entitled logically to make such assumptions about other people. In physiological terms, emotional states in humans are typically accompanied by autonomic changes, but these are not a reliable guide to identifying particular emotional states. Most animals, at least vertebrates, react to stressors in roughly the same way whether their emotional response is one of fear, of aggression or sexual nature.” (Abrantes, 2019)

  • A conscious experience of emotion requires: (1) the level of consciousness, (2) to have some somatic content of conscious experience (how the emotion feels in the body), (3) to have some cognitive content of conscious experience (a motivational component).

    Note: Psychologists, for example, see hunger as a motivational or a homeostatic state 

  • Many philosophers distinguish between awareness and consciousness. Awareness is a form of perception while consciousness involves a special kind of self-awareness. Consciousness, in this view, involves a propositional awareness that it is I who am feeling or thinking

  • There is no scientific consensus on whether behavioral evidence is sufficient to conclude that non-human animals have conscious experiences of emotions.

Learning and emotions:

  • Emotions involve innate and learned aspects. “The development of emotions involves a complex interaction between genes and environment, between innately programmed mechanisms and learned associations.” (Adolphs, 2018)

  • “In classical conditioning, the US (Unconditioned Stimulus) is called reinforcement because the entire conditioning procedure depends on it. Note, however, that in classical conditioning, the organism has no control over reinforcement: It occurs when the experimenter wants it to occur. In other words, in classical conditioning, reinforcement is not contingent on any response made by the organism.” (Olson 2013, p.61)

  • “Watson showed that our emotional reactions can be rearranged through classical conditioning. In this experiment, the loud noise was the US, fear produced by the noise was the UR, the rat was the CS, and the fear of the rat was the CR. “ (Olson 2013, p.545)

  • “Similarly, consider the dog trainer who reinforces the appropriate response to various commands, such as sit, stay, come, and fetch. Each appropriate act is followed by a bit of food. Described in this way, this seems to be a simple case of operant learning. But notice that the commands are sometimes followed by food; this pairing of stimuli (command and food) is the essence of Pavlovian conditioning. We may expect, therefore, that the dog will not only learn to respond appropriately to the commands but will also come to enjoy hearing the commands and may even salivate when it hears them. Operant and Pavlovian learning are like buddies. They are not identical, but they spend a lot of time together. “ (Chance 2014, p.142)

  • “Eysenck and Rachman see the case of Little Albert as a model of how all phobias are acquired. But this can only account for the initial learning of phobias (through classical conditioning), not for their persistence (which occurs through negative reinforcement).” (Please, see references)

Emotional states proprieties on dogs:

  • Dogs show strong evidence of two emotional states properties, “Generalization” and “Social communication” (Adolphs, 2018)

  • Generalization: Emotions can be generalized over stimuli and behavior, much of which depends on learning. This creates something like a “fan-in”/“fan-out” architecture: many different stimuli link to one emotional state, which in turn causes many different behaviors, depending on the context. Persistence and generalization underlie the flexibility of emotion states. 

  • Social communication: In good part as a consequence of their priority over behavioral control, emotion states are pre-adapted to serve as social-communicative signals. They can function as honest signals that predict another animal’s behavior, a property taken advantage of not only by conspecifics but also by predators and prey. 

  • The social communication between dogs and humans are clear examples that emerged in their close interaction both through evolution and through learning.

  • Figuring out what dog behaviors mean is thus a very complex work because they can indicate emotional functions carried over from their wolf ancestry (e.g, social submission), but they may also have generalized to indicate new functions (eg. play or instrumental behavior to get the owner to give food).

  • Dog owners tend to believe that they can tell if their pet feels guilty—but they are actually a chance in recognizing whether the dog did something wrong or not.

Note: ‘Dogs feeling guilty’ is one of the popular myths in the dog training world. This one creates severe punishment situations in dogs and ‘funny’ videos on the Internet.

As professionals, we should be prudent. Our current knowledge only allows us to say that the dog exhibits pacifying behavior and, in behavioristic terms, that the dog associates a specific approach (verbal or bodily) of the human with something unpleasant, not with something it did hours ago. We cannot confirm or deny guilt in dogs. We don’t know if it exists or how dogs show it.

These are complex concepts to explain in other species (even in ours). By stating they fell guilty, we may make the mistake of anthropomorphism. By denying it, we may make the mistake of anthropodimorphism.

You shouldn’t fear to say “I don’t know,” or “I cannot prove it” in these specific subjects. 

“Absence of evidence is not evidence of absence.” – Carl Sagan

“A difference of degree, not of kind.” – Charles Darwin

More than training—Lead respect

  • I use the lead as a communication link, where I try to transmit all information with minimal pressure possible.

  • Body language has an important key role for the other species naturally follow us.

  • Whenever we move, the lead moves rhythmically without pressure (with a smile). When we stop, the lead touches the ground.

  • Teaching this natural way requires patience and self-control.

  • We should be aware that the lead is not natural for dogs.

  • We must respect both sides of the lead, and that is why we should use a lead that allows a free movement without pressure (at least 1,70m length).

  • With the lead placed on our palm. We move forward, back and forth with no quick movements, we should give the opportunity to the other species to decide and follow us naturally, which is why our body language is so important.

  • Inevitably, some pressure can happen. We should deal with it in a kind way, and solve the problem efficiently according to the situation, without creating a harmful situation.

My three maximum self-imposed ethical limits in case of lead tension. One finger for small dogs, two fingers for medium dogs and three fingers for large dogs. If we need to make more pressure than that, it means that something is wrong and we need to analyze the present conditions. Note: Not applied to life-threat emergencies. Note 2: Be aware that the tension limits vary with the individual (human and dog) and the present conditions. These ones are applied only to myself in a calm environment

More than training—Communication

  • It is my opinion that we should practice mutuality communication, that is, a communication where the sender and receiver benefit from the interaction.

  • I also believe that communication must be something natural and individual, without any tool between.

  • Interspecific communication, whatever it may be, will always require self-control and sometimes reflection because the language translates emotional states.

  • Sometimes there are humans and nonhumans incompatible for a relationship and for communication, we need to keep in mind that we are not always able to communicate and we should not impose the communication and relationship as we want and whenever we want.

  • Interspecific communication creates a bond.

  • Bonding in animal behavior is a biological process in which individuals of the same or different species develop a connection. The function of bonding is to promote cooperation (Abrantes, 2015).

  • Looking into one another’s eyes is only bonding for a while, but surviving together may be bonding for life—and this applies to all social animals, dogs and humans included.

More than training—Mutual respect and feedback

Dr. Roger Abrantes (2015) in his book “Animal Training, My Way” considers that a relationship must be based on mutual respect independently of who is in it. Interacting with social species, allow us to create a bonding. Bonding in animal behavior is a biological process in which individuals of the same or different species develop a connection. The function of bonding is to facilitate co-operation (Abrantes, 2015). 

Abrantes (2015) also refer we need to understand the other species and feeling a certain empathy with him. He describes emotional empathy as “the capacity to respond with an appropriate sentiment to someone’s psychological states” and cognitive empathy as “the capacity to understand someone’s perspective or feelings”. 

Feedback exists between two variables whenever each affects the other. Positive feedback exists when the value of y tends to increase the value of x, which in turn increases the value of y. 

Positive feedback systems are inherently unstable, but they can have certain advantages in complex systems containing built-in constraints. 

Negative feedback systems are characterized by the situation where the value of x is diminished as the value of y increases. The consequence is that the value of y therefore decreases. 

The value of y is then said to be under negative feedback control. Such negative feedback systems are common in the control of animal behavior. 

Movement & Motivation System (Barata, 2008)

I have an empirical approach to movement and motivation in animal training to be published in 2020. Bellow, I’ll give you a general idea of what I’ve been working (and still working) in the last 11 years about it.

  • Movement is the act of changing place or position of the whole body or by one or more of its parts. Movement is one of the characteristics of living organisms. Every kind of movement catches our attention, especially the unexpected movements of another individual or object. 

  • Motivation is all factors that cause an organism to behave or act in an objective or satisfactory way.

  • Motivation can be influenced by physiological drives (hunger, thirst, need for oxygen, sleep and rest, avoidance of pain, control of elimination, sexual desire, and heat and cold) or by external stimuli. 

My observations and practical analysis suggest that this system if correctly applied to the individual, creates a natural balance in communication during the training in order to receive the desired behaviors, and to prevent the undesirable behaviors provided by the factors that can be influenced at the moment; It increases the attention of the human to all present stimuli, increasing the probability of avoiding/preventing them; and it can be implemented together with other learning techniques (e.g social/asocial observational learning).

Some factors that influence the M&M system

  • Environmental cues: All stimuli that can affect the concentration of the participants at the moment.

  • Animal economic: All the physiological and emotional factors at the moment that can affect the performance of the participants, including attention, decision-making, demand functions, motor-coordination, behavioral resilience (behavioral resilience: dealing with stress, adaptation, and the situation itself), game theory (situations where players choose different actions in an attempt to maximize their returns) and previous learning.

  • Human incompatibility: Inadequate training techniques or non-adaptation due to individual and/or environmental conditions at the time due to their emotional state and/or training procedures.

Animal trainers questions

I have a view that we should not “training” just because yes. So, I always use these three questions before spending the time and energy of myself and the other species.

  • What do I need to teach? (Which are the individual needs?)

  • Why do I need to teach it? (Does the individual really need it and it worth spending the time and energy of both?)

  • How do I teach it? (Do I have all the tools and knowledge to do it?)

Skills teaching programming 

Dr. Roger Abrantes (1993) has created a training language called SMAF, an acronym to Signal, Meaning, And Form. SMAF is a language to describe learning with all its components. Its objective is to enable us to plan our session with the highest possible degree of precision and analyze the expected and observed results, regardless of the species. SMAF defines and transcribes terms and processes (e.g., reinforcers and inhibitors, reinforcement schedules, etc…).

Below, I will illustrate the most common signals we use to teach a dog with their meaning and form.

To simplify, I will write a single line with:

The skill to teach => The meaning of the signal => The form of the signal.

  • Sit(Skill) => Put your bottom on the ground AND keep it there until you receive another signal(Meaning) => Sit,sound + Sit,hand(Form)

  • Down(Skill) => Put your belly on the ground AND keep it there until you receive another signal(Meaning) => Down,sound + Down,hand(Form)

  • Stand(Skill) => Put the four paws on the floor with the legs in vertical position AND remain them there until you receive another signal(Meaning) => Stand,sound + Stand,body(Form)

  • Yes(Skill) => Continue(Meaning) => Yes,sound(Form)

  • No(Skill) => Stop(Meaning) => No,sound(Form)

  • Free => No more behavior will be reinforced(Meaning) => Free,sound + Free,body

Note: I do not use the “stay” (or “wait”) signal. I don’t see any sense of it at the moment. My ethological background and practical experience made me question how a “do nothing” concept can be understood by other species (or even by our)? In my opinion, reinforcing the increase of the duration of a given signal, like “sit,” seems to be a clear and the easiest way to teach the “stay,” which is already included in the signal. The “wait” signal can easily be taught with the “yes-no” skill.

When nothing works

As I wrote above, we are permanent students. Sometimes, everything we are doing simply doesn’t work. It happens sometimes. I always tell to my students, colleagues and dog owners that, when it happens, we should stop. The silence, observation, and thinking are the best teachers at that moment (image below).

This is what I say to all students, trainers and dog owners over these years when things are not working. Stop for a while. Observe and think about how we can improve communication. Photo by Tilde Detz-Jensen,


I suggest the article below from Dr. Abrantes, with an interesting perspective about the subject.

In conclusion, it much more than training, just enjoy every moment with your dog, cat, horse, guinea pig, etc.

Last update: March 8th, 2020.


Abrantes. R. 2013. The 20 Principles All Animal Trainers Must Know. Wakan Tanka Publishers.

Abrantes, R. (2019). Do Non-Human Animals Have Consciousness? Ethology Institute. Retrieved Mar. 8, 2020.

Adolphs, R. & Anderson, D.J (2018). The Neuroscience of Emotion, A New Synthesis. Princeton University Press.

Abrantes. R. 2015. Animal Training My Way—Merging Ethology and Behaviorism. Wakan Tanka Publishers.

Barata, R. (2008). Movement and Motivation System in Dog Training—An Empirical Approach. Personal Portfolio (Expected to be published in 2020).

Barata, R. (2009). Reward or Reinforce? vs Punish or Inhibit?. Personal portfolio (unpublished).

Barata, R. (2009). Training tools and Fashionism. Personal portfolio (unpublished).

Barata, R. (2010). Lead Respect. Personal Portfolio (unpublished).

Barata, R. (2014). To stay, or not to stay?- that is the question. Personal portfolio (unpublished).

Barata, R. (2014). Animal Training and Pseudoscience—critical reasoning. Personal portfolio (unpublished).

Barata, R. (2016). Signals precision in animal Training. Personal Portfolio (unpublished).

Barata, R. (2019). Positive reinforcement. Encyclopedia of Animal Cognition and Behavior. Springer.

Batenson, P. (2017). Behaviour, Development, and Evolution. Openbook Publishers.

Chance, P. (2014). Learning and Behavior. Wadsworth-Thomson Learning, Belmont, CA, 7th, ed.

Cleveland, J., & Snowdon, C. (1982). The complex vocal repertoire of the adult cotton-top tamarin (Sanguinus oedipus oedipus). Zeitschrift für Tierpsychologie, 58, 231-270.

Eysenck, H.J. & Rachman, S. (1965). The Cause and Cure of Neurosis. London: RKP. 

LeDoux, J. (2012). “Rethinking the emotional brain.” Neuron 73 (4): 653–76. 

McFarland, D. (2006). A Dictionary of Animal Behaviour. Oxford University Press. 

Olson, M. & Hergenhahn, B. R. (2016). Theories of Learning, Ninth edition. Psychology Press.

Otte, D. (1974). Otte, D. (1974). Effects and function in the evolution of signaling systems. Annual Review of Ecological Systematics, 5, 385-417.

Robinson, J. (1984). Syntactic structures in the vocalizations of wedge-capped capuchin monkeys (Cebus olivaceus). Behaviour, 90, 46-79.

Skinner, B. F. 1986. What is wrong with daily life in the Western world? American Psychologist, 41(5), 568-574. Retrieved Jun. 29, 2019.

Watson, J.C., Arp, Robert. (2015). Critical Thinking—an introduction to reasoning well. Bloomsbury Academic

Zahavi, A. (1987). The theory of signal selection and some of its implications. In U. P. Delfino, ed., International Symposium on Biology and Evolution. Bari: Adriatica Editrice, pp. 294-327.

This website uses cookies. By continuing to use this site, you accept our use of cookies. 

error: Alert: Content is protected!