C&C Ch.2 Flashcards
a simple definition of adaptation
the fit of structure to function
what did 18th Century British theologians do?
they introduced the term adaptation to argue that the appearance of design in the features of living creatures proves the existence of a supernatural designer
biological evolution involves
changes over time in the characteristics of populations of living organisms
give an example of how evolution can be studied during a human lifetime
when changes occur in a single character - eg the increase in the frequency of strains of bacteria resistant to penicillin within a few years of the widespread medical use of penicillin.
give an example of evolution which may take millions of years
the emergence of a major new design of organisms - eg the transition from reptiles to mammals
state a key insight of the founders of evolutionary theory, Charles Darwin and Alfred Russel Wallace
- changes at all levels are likely to involve the same types of processes
- major evolutionary changes largely reflect changes of the same type as more minor events, accumulated over longer time periods
what does evolutionary change rely on?
the appearance of new variant forms of organisms: mutations
what are mutations caused by?
stable changes in the genetic material that can be transmitted from parent to offspring.
give 3 different degrees of effects of mutations
- no detectable effect
- relatively small effects on a simple trait (change in eye colour, acquisition of antibiotic resistance, alteration of no of bristles on the side of a fruitfully)
- drastic effects on development(eg mutation of D. melanogaster that causes a leg to grow on the fly’s head in place of its antenna)
how often does the appearance of any particular kind of new mutation occur?
very rarely, with a frequency of around one per 100,000 individuals per generations or less.
describe the theory of evolution by natural selection by Darwin and Wallace
- more individuals of a species are born that can normally live to maturity and breed successfully, so there is a struggle for existence
- there is individual variation in many characteristics of the population, some of which affect an individual’s ability to survive and reproduce. successful parents of a generation may differ from the population as a whole
- there is likely to be a hereditary component to much of this variation, so that the characteristics of the offspring of the successful parents will differ from the characteristics of the previous generation in a similar way to their parents
if the process of evolution by natural selection continues from generation to generation, there will be
a gradual transformation of the population, such that the frequencies of characteristics associated with greater survival ability or reproductive success increase over time
describe most mutations
- mutations affecting a particular trait arise all the time regardless of whether or not they are favoured by selection
- most mutations either have no effects on the organic or reduce its ability to survive/reproduce
when is the process of change especially likely?
if a population is exposed to a changed environment, where a different set of characteristics is favoured from those already established by selection
subsistence
the action/fact of maintaining or supporting oneself at the minimum level
