Water Water is a vital ingredient for thriving plant and animal

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Transcript Water Water is a vital ingredient for thriving plant and animal

Water is a vital ingredient for thriving plant and animal life. However, in
many regions it is in scarce supply. Xerophytes, plants adapted to drought
conditions such as the cactus, have a number of adaptations to deal with
water scarcity. Cacti may have spines to reduce transpiration and
discourage grazing. Succulents have stems and leaves which can retain
water and a waxy cuticle to reduce transpiration. Evergreen trees have
needle-like leaves also to reduce transpiration during the dry winter
a). Cactus
b). Succulents
c). Evergreen Trees
Temperature influences the rate of physiological processes. Animals
that can maintain a fairly consistent temperature may do so by
harnessing their metabolism. Mammals are one example of these socalled warm-blooded species. However, cold-blooded species, such as
reptiles, must acquire their heat from their environment. Thus reptiles
can often be seen "sunning" themselves to raise their temperatures.
Lizard sunning itself on a rock
Interaction Among
Species Competition
Species with their competing needs and drive to perpetuate their species
compete on a variety of levels. Individuals of the same species may compete
for resources in intra-species competition. However, different species may
also compete in order to establish new territory and so acquire new resources.
The purple loosestrife is a plant introduced to the waterways of North America.
Originally a garden plant, its vigorous growth and extensive root system outcompetes many native plants. In many regions it is seen as a significant
problem invader.
Interaction Among Species - Competition
Purple loosestrife
Predation, Parasitism, and
Species may also interact by using other animals as a source of energy
such as by preying upon them. When a cheetah feeds upon a hyena it is
acquiring energy indirectly from the plants the hyena grazed upon.
Grazing requires large amounts of time to indirectly acquire the energy of
the Sun that the plant attained through photosynthesis.
However, parasitism also sees one organism acquire energy from
another, though not by killing the objective organism outright. Mistletoe
is a parasitic plant that acquires its resources by growing on trees.
Cheetah chasing hyena
Grazing bison
Bogs are waterlogged areas that are characterized by sphagnum mosses
and large accumulations of organic matter. Although some bogs remain as
wetlands for long periods of time, in many cases the growth of vegetation
eventually leads to the establishment of grasses, shrubs and eventually
trees. This change over time is referred to as succession.
*See animation on bog succession in the geodiscoveries section of your text’s website.
Evolution, first proposed by Charles Darwin, is based upon the way that a
varied population of individuals will react and survive according to conditions
and their ability to survive. A modern example is the peppered moth which in
unpolluted regions is light grey, but occurs in polluted regions as black.
Variation within the species creates both forms, but only the black form
survives if forced to live on blackened surfaces resulting from heavy pollution.
Charles Darwin
Peppered Moth
The finches of the Galapagos Islands present an example of allopatric
speciation - in other words, the different conditions on different islands
led to one colonizing species creating a variety of forms.
In contrast, sympatric speciation sees a large population separated into
separate species such as the cichlide fish of the African Rift Valley.
Galapagos Island finches
Cichlid fish from Africa
Extinction is where a species disappears entirely due either to
natural or human-induced factors. Dinosaurs became extinct along
with a variety of other species including trilobites. These seemingly
successful species were unable to maintain a population due to
changes in the environment or perhaps other variables.
However, today we see evidence of human-induced extinctions, such
as the rapid loss of the Dodo in Martinique due to hunting. Today, the
Guam kingfisher can no longer live in Guam due to the arrival of
snakes. Although maintained in zoos, the Guam kingfisher is unlikely
to be returned to its homeland in the near future.
Guam Kingfisher
Some plants and animals now cover large areas because of their
success in being dispersed. Coconuts remain viable while they float
across the ocean surface and consequently they may be found in a
range of tropical locations. Animals may also be dispersed effectively.
Rats have found humans and their efficient transportation systems an
effective way to reach new territory.
Coconut Palm
Distribution Patterns
Biogeographic regions have also been created by the processes of continental drift.
Consequently, many species over millions of years have maintained similar
characteristics though reside in distant regions. The large flightless birds such as
the cassowary are exemplary of this process.