Populations, Natural Selection And Evolution Essay, Research Paper
Outline
how population size can be affected by natality, immigration, mortality and
emigration. Natality = + Immigration = + Mortality = – Emigration = – Draw
a graph showing the sigmoid shaped population curve. ? Explain
reasons for the exponential growth phase, the plateau phase and the
transitional phase between these two phases.
Lag Phase o
Only a few individuals to breed
Exponential Growth Phase o
Numbers increase. More individuals are available for
reproduction. o
Population grows at an every increasing rate, with no
inhibitors
Plateau Phase o
There is a limit to the number of individuals that a
community can support. o
The population has reached its environment?s carrying
capacity. o
Factors limit population growth
Death Phase o
The high population causes carrying capacity to
decline. o
Pollution builds up. Population rapidly declines.? Define
carrying capacity. The maximum number of a species that can be sustainably
supported by the environment. List
three factors which set limits to population increase
Pollution
Amount of food available
Predators State
that population trends tend to produce more offspring than the environment can
support Explain
that the consequences of the potential overproduction of offspring is a
struggle for survival
Overpopulation
Scarce resources
Survival of the fittest State
that the members of a species show variation Explain
how, by natural selection, the best adapted will survive to breed.
Natural
selection keeps the disorganizing effects of mutation and other processes in
check because it multiplies beneficial mutations and eliminates harmful ones.
Natural
selection may occur not only because of competition but also because of some
aspect of the physical environment, such as inclement weather. Moreover,
natural selection would occur even if all the members of a population died at
the same age, simply because some of them would have produced more offspring
than others. Discuss
the theory that species evolve by natural selection Natural selection can be defined as the differential
reproduction of alternative hereditary variants, determined by the fact that
some variants increase the likelihood that the organisms having them will
survive and reproduce more successfully than will organisms carrying alternative
variants. Natural selection is quantified by a measure called Darwinian
fitness, or relative fitness. Fitness in this sense is the relative probability
that a hereditary characteristic will be reproduced; that is, the degree of
fitness is a measure of the reproductive efficiency of the characteristic. Evidence
Fossil Record
Structural Similarities
Embryonic Development
Molecular Biology Discuss
the need for evolution in response to environmental change
Darwin
maintained that competition for limited resources results in the survival of
the most effective competitors.