Methods to Measure Biodiversity and Relative Strengths and Weaknesses - Essay Example

Biodiversity Answer Biodiversity describes about the diversity and distribution of life on Earth. Biodiversity can be defined as variability amongliving organisms. This encompasses species, ecosystems, genes and their various forms. From three different perspectives, it can be defined as per the following. Species Diversity This specifies the variety in various types of organisms that inhabit in a specific area. Genetic Diversity In a single species, several combinations of different genes and its patterns are found. This largely speaks about genetic diversity. Genetic adaptations to the local conditions differentiate these species. Ecosystem Diversity This speaks about the variety of habitats in a region. Example is San Francisco Bay-Delta ecosystem constituted of wetlands, estuaries, grasslands, fresh and salt water, rivers". Methods to Measure Biodiversity and Relative Strengths and Weaknesses Ecologists measure diversity in three different scales. Alpha diversity is measured by counting the number of species within the ecosystem. Beta diversity measures diversity between two ecosystems – comparing species that are unique for each ecosystem. Gamma diversity measures overall diversity for several ecosystems within a specific region. Various methods have been created to measure biodiversity empirically. Whittaker (1972) specified three metrics to measure biodiversity that encompasses species richness. Species Richness It is simply a count of species; however, it does not take into account its abundance and their relative distributions. Against this, species diversity will count on species richness and its evenness. Simpson Index This is a good statistical method used quantify the biodiversity of a specie. It measures number of species and abundance of each species. It also measures total numbers in each species. Species diversity is derived from the mathematical formulae that give highest values to ecosystems. It requires huge number of workers, skill and resources. Shannon-Wiener Index This method quantifies the uncertainty associated with the prediction. The index gives how the species is distributed in an ecosystem. This is the most widely used index as far as community ecology is concerned. The average uncertainty goes up as the number of species increases and the distribution becomes even. Answer 2. Insects have their body structure made of head, thorax and abdomen. The head part consists of eyes, that could be simple or compound, and antennae to provide smell sense. The thorax is made of fused segments with a pair of legs. The two other fused segments have a pair of wings with variations as per the groups. The abdomen part contains digestion, production and excretion organs. The primary adaptation to life on land was possible through the development of internal tubes for breathing. The internal tubes are connected to the trachea delivering air to the tissues. The tubes get open to the outer area through spiracles to allow air to enter through the trachea and tracheoles. The ends of tracheoles penetrate cells to provide oxygen and eschew carbon dioxide. Each of the three thoracic parts in all insects consists of a pair of legs and the hind legs possess a pair of wings. That is how six legs and four wings are found in most of the insects. Paleoptera is defined as most primitive winged insects. That means all paleopterans will have a specific physical characteristics or wings as a common feature. This does not mean that it includes all winged insects; it just includes primitive ones. Paleoptera and Neoptera differ to each other in their wing articulation. The subclass Pterygota has two further divisions called the Exopterygota and the Endopterygota. Exopterygota insects have life cycles that pass through three stages – egg, nymph and adult. A larger number of insects such as Roaches and Mantids; Dragonflies and Damselflies; Crickets, Grasshoppers and Locusts; True Bugs are part of Exopterygota division. In contrast, Endopterygota have life cycles that have four life cycle stages – egg, larva, pupa, and adult. The pupal stage is a rest period in these kinds of insects. Insects get functional wings on maturity from pupal stage to adult stage. Insects such as Beetles; Butterflies and Moths; True Flies; Ants, Bees, and Wasps fall in this category. Odonata (Dragonflies and Damselflies) within the superorder of Exopterygota have two most distinct features that are extremely large eyes and a long abdomen. Odonates have a distinct feature to hover, fly backward and then take off just like helicopter. They can rotate their head almost 360 degrees. They inhabit all parts of the world but Antarctica. Beetles (within Superorder Endopterygota) constitute almost one-fourth of all the species on Earth. Over 350,000 varieties are found on this planet. Beetles have been found to feed on other insects, organic matter, manure, plants. True flies are diverse groups that include mosquitoes, gnats and variety of flies. It has just one pair of wings. It has a modified wing known as halteres and work like a gyroscope necessary to stabilize its flight. True bugs (in Exopterygota superorder) have mouthparts that have feature of piercing and sucking; that is how they feed on plant fluids and can penetrate plant tissues. Butterflies and Moths constitute second largest group in the Endopterygota category of the insects. They are found in most part of the globe except Antarctica. They have mouthparts suitable to work as a sucking tube. There is clear evidence that the insect fitness is attributable to their relative age, low extinction rates; however, it has been found that niche specialization is linked with higher extinction risk. There are also evidences that diversity has increased due to complete metamorphosis, and wind folding. Smaller body is associated with low extinction risk. Mouthpart diversity is more in insects. Thus, it is amply clear that wing articulation and adaptation of certain muscles for flight have been instrumental in bringing winged insects into dominance. Answer 3. The Sea Otter is a marine mammal and the largest member of the mustelid family. Button nose of sea Otter serves as a life-saving function. Labyrinth of membranes within the nasal passages is a device that works as water conservation and heat exchangers. These structures are necessary to conserve body heat and water. In the absence of this device, sea otters would die within a few hours. Bergmanns rule defines why Alaskan Sea Otters are larger in size than Californian Sea Otters. It is worth knowing that Californian Sea Otter weighs only 64 pounds against 80 pounds weight of Alaskan Sea Otter. Surface-to-volume ratio in case of a larger animal will be lesser than smaller animal. That will bring down heat loss-to-heat generation ratio. That means animal living in colder region will adapt to colder environment through its larger size. The Long-beaked Common Dolphin is a mammal having streamlined shape that provides it a low drag coefficient. Dolphin and whales both move through movements of their tail-fin. The unique thing with dolphin is that they have fins on their backs and they make use of them to cut through the water surface. Evolutionary process has metamorphosed the nasal opening in rough-toothed Dolphin to a dorsal position. Dolphins possess a blowhole at the top of their head to inhale air. They can exhale and inhale rapidly within half a second before going back in water. Dolphin has capacity to hold breath for about 15 minutes. With the evolution process, dolphin developed larynx and throat that enabled them to make high-pitched sounds for eco-location. They make day-to-day communication through lower pitched sounds with other members. Answer 4. Plant life began in the form of algae in the sea. Algae are one-celled or many-celled organisms. They derive their food through photosynthesis. Their cell membranes are porous and water that surrounds them will provide them all material necessary for survival. Stems and leaves of plants are covered by cuticle – a protective layer secreted by cells that prevents the loss of water. Cellulose found in plant cell walls helps and support land plants. Life on land means lack of water and thus, lesser chance of nutrients that can enter into the cell. Adaptation changes structures of plants such that nutrients and water move to all plant cells. The structures also serve the purpose of supporting the plant. Adaptation also means change in reproduction in order to survive on land. Water-resistant seeds in flowers or cones develop into fruits for reproduction process. Mosses are made of non-vascular plants. Green, leaflike growths around a central stalk is a characteristic of Mosses. They grow on tree trunks or on the ground. Usually, they are found in damp fields. Many cells make the rhizoids in Moss. Spores, also called reproductive cells, form in the caps of stalks. Spores of mosses are carried by the wind. Mosses usually grow easily in disturbed environments such as a forest fire or in lava fields. That is why Moss is also known as pioneer species because of its ability to grow first in the disturbed area. Ferns like mosses reproduce by spores and not by seeds; however, they are different from mosses in their structure having vascular tissue. Ferns, being seedless vascular plants have its tissues made up of tubelike long cells. These cells provide minerals, water and nutrients to the plant. Moss having nonvascular structure is made of only a few cells and absorbs water from the environment and that poses limitation on its growth. Ferns due to its vascular structure can grow thicker and bigger because they can distribute water and food to all cells. Thousands of species of ferns are found on Earth. Gymnosperms are seed plants. They are vascular plants producing seeds but they are not protected by fruit. That is why the name gymnosperm means naked seed in the Greek. They do not have flowers. Conifers are a kind of gymnosperms. Conifers have two kinds of cones-- male and female. Cones serve the purpose of reproduction in conifers. Female cones produce seeds. Answer 5. In nature there are two methods of reproduction. Production that happens without the interaction of two sexes it is known as asexual reproduction. When two cells called gametes from male and female source participate, the resultant reproduction is known as sexual reproduction. The cell division will be known as asexual reproduction because reproduction is from a single cell and no other cell is involved. Many examples of asexual reproduction are found in plants. Bacteria, Amoeba, Hydra, Paramecium, reproduce through asexual reproduction. Many plants and animals can reproduce in both ways. In an animal kingdom, jellyfish is an example that can reproduce both ways. Some of the other organisms that can produce sexually and asexually are Cactus, Daffodil, Starfish, Sponge, and Mushroom. The major advantage of asexual reproduction is that it is quick and can form colonies in short period. Asexual reproduction is suitable when conditions are ideal for growth. Sexual reproduction provides variation and that is a basis for evolution and that is its biggest advantage. Ridley (2003) argues that the 50:50 sex ratio is prevalent everywhere in nature. Whenever a population takes a deviation from it, natural selection brings it back to 50:50. This is most understood process of adaptation of sexual reproduction. Fisher and Zahavi proposed their theories on sexual selection. Both theories consider sexual selection as a preference of females in their choice to mate and the theory has been tested in several species. According to Fisher, if there are higher males than females, then males have a lower chance of mating. There is a disadvantage to males and disadvantage to a female who produces extra sons. That means sons will have a lower reproductive success than daughters. The same argument also works in the opposite way when there are higher females. In short, natural selection tries to stabilize the sex ratio. Hamilton argues that sexual display such as tail in case of peacock is an indication of its health causing females to mate with them. There is growing evidence that female birds in some species such as Red-winged Blackbirds or Marsh Wrens choose those males for mating that hold most desirable territories. In a Widowbird study, it was found that those males whose tails were longer had most new mates in comparison to those whose tails were shorter. The study concluded that females mated with those males having longest tails. In another study of Parasitic Jaegers on Fair Isle near Scotland, it was found that females prefer to mate with males having dark phases. Thus, female choices enhance the fitness of the dark males. Fishers theory begins with the assumption that competition for mates is across whole population and Hamilton indicated that sex ratio will be skewed in those species where a local mate competition is limited. In pyemotid mites the sex ratio is female biased. In Pyemotes ventricosus also the sex ratio is female biased because the males are not competing with whole population for mates. Works-Cited Ehrlich Paul; Dobkin, David; Wheye, Darryl. Stanford.edu. Sexual Selection. 4 October 2012. . Friesen, Larry. Adaptation. Nature Journal. 4 October 2012. . Mayhew P.J. Why are there so many insect species? Perspectives from fossils and phylogenies. NCBI. 4 October, 2012 . Ridley, Mark. Adaptations in sexual reproduction. Evolution. 4 October, 2012 Ukalova-Peck, Jarmilak. Carleton University. Origin of the insect wing and wing articulation from the arthropodan leg. 4 October, 2012 Whittaker, R. H.. Evolution and measurements of species diversity. Taxon 21:213-251 http://www.sebring.k12.oh.us/McKinley_Jr__Sr__High_School/Naples/7th/chap09.pdf Read More