The Argument-
Mr.
Shenk proposes that inheritance is not only “the passing on of… genes” (p. 108),
but also includes the “crucial external ingredients, such as… culture,
knowledge, attitudes, and environments” (p. 108). This is evident in the cattle-raiding
Kenyans who pass on their “knowledge … to attain maximal nutrition, inspiring
stories,…attitudes and habits” (p. 108) even though their genes are not
significantly different than other cultures that do not raise cattle. These
external influences account for up to 40% of species characteristics. But how
do species that mature independently of their parents (ie. Sea Turtles, Salmon,
Frogs, etc) avoid succumbing to natural selection? How do animals that cannot
undergo imprinting because of their lack of stimuli develop to their fullest
potential? If smarter, more adapted, and more likely to survive and reproduce
offspring are produced by parent involvement, why then do Sea Turtles still
develop in exile? How does Mr. Shenk's proposal relate to the biological theme of Evolution? Discuss the advantages and disadvantages of independent maturation (Chapter 54) in your response.
Josh Gerber
(grbr_jsh@yahoo.com)
Some species, mainly r-selected species, develop away from their parents despite the benefits of being raised by parents. These species must learn the behaviors necessary for survival apart from their parents. Although imprinting would seem to be a problem, as the neonates have no parents to emulate, a young organism simply needs to have innate behaviors that the young organisms don’t need their parents to learn. For this, organisms have fixed action patterns. Fixed action patterns are unlearned, and therefore organisms can respond to a stimulus without actually having to see their parents do it first. For example, stickleback fish have an innate aggressive response to the color red (Campbell 1121). Therefore, organisms can perform behaviors such as hunting and mating without imprinting on their parents.
ReplyDeleteDavid Shenk states that “culture, knowledge, attitudes, and environments are also passed on in many different ways” (Shenk 108). Perhaps one of these ways is to learn without the help of the parents. By simply being placed in the same environment that the parents grew up in, organisms that lack parental care can avoid succumbing to natural selection by interacting with and learning from the surrounding environment. Many of these types of organisms do not need parental support to reach their fullest potential, because the organisms have innate knowledge of the behaviors necessary to survive and reproduce.
These differences in parental care general come down to the difference between K-selected and r-selected species. According to the University of Oxford, St. Peter’s College, the University of Helsinki, and Yale University, parental care increases the chances of survival of the offspring, but decreases the chances of future reproductive success, and the amount of parental care can decrease with increased competition between offspring. Thus, competition between offspring can provide for development of species lacking parental care. Also, parental care, usually given by K-selected species, means that adults must spend more time with their children in order for their children to be more likely to survive. However, species receiving little parental care, usually r-selected species, can give birth to many species at once. Therefore, there are much more chances for some individuals to survive and reproduce, even though each individual is less likely to survive than one that receives parental care. Furthermore, adults can survive for longer and reproduce for longer because adults do not need to expend energy caring for the young (that of course excludes the instances when the parent dies because the parents expends all of its energy reproducing once). Both K-selection and r-selection have advantages and disadvantages, and both types of species manage to survive and reproduce regardless of the amount of parental care the species receives.
This relates to the theme of evolution because the presence or lack of parental care impacts the amount that natural selection affects the species. Evolution is the way that species develop and adapt to the environment based on the ability of especially adapted species to survive and reproduce. When organisms receive more parental care, natural selection determines less of the survival of the organism, because the parent can determine the development of the young organism. More involved parents give their children a better chance to survive and reproduce. Species lacking parental care, on the other hand, are more subject to natural selection, because those organisms rely on innate knowledge of certain behaviors, and certain organisms lacking those innate behaviors cannot survive and reproduce. In fact, r-selected reproduction can be a selective advantage when organisms live in a relatively non-threatening environment, and therefore many individuals are likely to survive without parental care, so reproducing many organisms will increase the chances of the parent’s genes being passed along.
Aaron Zalewski (bitquest@yahoo.com)