Darwinian fitness(animal behaviour)

Darwinian fitness (animal behavior)

1. Darwinian fitness aNIMl BEHAVIOUR Abhinaya alley Bsc honours zoology Sikkim university

2. Darwinian fitness mostly focuses on individual fitness It is widely recognised as a measure of the capacity to produce offsprings Fittest is not that which best fits the existing environment but the fits are those who fits their existing environments and whose descendants will fit future environments Thus, in measuring fitness, it is to look for probability , after a given lapse of time, the animal will have left descendants

3. Variation among individuals among populations: some have greater reproductive success than others Individuals that produce a higher number of viable offsprings are said to have greater “ Darwinian fitness ”. An individual’s fitness depends upon its ability to survive to reproductive age, its success in mating, fecundity of the mated pair, and the probability of survival to reproductive age of the resulting offspring Fitness of genotype can be measured by means of numbers of its progeny, counted at the same stage of life cycle. Hence, fitness of an individual must takes its age into account : potential for reproduction changes with age Ronald Fisher (1930): Concept of the age-specific reproductive value an index of the extent to which the members of a given age group contribute to the next generation between now and when they die

4. Survival value of the hereditary trait within a population depends upon the extent to which the trait contributes to the reproductive success, which depends partly upon the selective pressures inherent in the environment Features that effect the reproductive success: Starvation, predation, etc. Failure to breed as a result of competition for mates or nesting sites. Failure of the young to thrive through lack of parental care, food or protection from predators Function of a trait is to increase , via natural selection, the genetic contributions to future generations

5. Behaviour biology

6. Evolutionary biologists make two distinctions between survival value: The individuals with high-survival traits are said to be well adapted to the environment in that they efficiently obtain food, avoid predators, etc. Survival value of a trait within a population depends upon how much the trait contributes to the reproductive success The term survival value is akin to the concept of fitness . Fitness is a measure of the ability of genetic material to perpetuate itself in the course of evolution. It depends not only upon the individual’s ability to survive but also upon its rate of reproduction and the viability of its offsprings

7. Four prepositions of tinbergen In a famous paper dedicated to Konrad Lorenz on his 60th birthday, Niko Tinbergen recognised that biologists working on behaviour focus on different types of problem -for instance, how the expression of a particular character is controlled - how it benefits the organism Tinbergen pointed out that four fundamentally different types of problem are raised in biology 1. Survival value: what is it for? 2. Ontogeny: How did it develop during the lifetime of the individual? 3. Evolution: How did it evolve over the history of the species? 4. Causation: And, how does it work?

8. Four questions apply broadly to any characteristic in living (and even some nonliving) systems. For instance, traffic lights could be thought of in terms of how they were assembled how their design evolved over time how their use increases the chances of survival of road users how they work

9. Animal behavior Behavior is what animals do. It can be defined more precisely as an internally directed system of adaptive activities that facilitate survival and reproduction. Ethology is the scientific study of animal behavior- particularly when that behavior occurs in the context of an animal's natural environment. Ethologists strive to observe, record, and analyze each species’ behavioral repertoire in order to understand the roles of development, ecology, physiology, and evolution in shaping that behavior.

10. Lorenz: he studied instinctive behaviour and FAP in animals such as geylag geese. K.v . Frisch: honey bee dance Tinbergen: study of instincts

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