Chapter 9 Biodiversity PDF

CHAPTER 9 BIODIVERSITY Contents: A. What is Biodiversity? B. Native, Invasive and Non-Native Species C. Extinct, Endangered and Threatened D. Philippine Biodiversity A. WHAT IS BIODIVERSITY? The term biodiversity (biological diversity) ref...

CHAPTER 9 BIODIVERSITY Contents: A. What is Biodiversity? B. Native, Invasive and Non-Native Species C. Extinct, Endangered and Threatened D. Philippine Biodiversity A. WHAT IS BIODIVERSITY? The term biodiversity (biological diversity) refers to the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life. Traditionally, there are three levels of biodiversity: genetic diversity, species diversity, and ecosystem diversity. 1. Genetic diversity is about the diversity of genes existing in the living world. Between and within different species there are different genes and different expressions of genes. And this genetic variability contributes to the multiplicity of life forms, physical and biological characteristics and, depending on the interaction with the environment, phenotypes. 2. Species Diversity describes the diversity of living species. There are millions of living species on Earth. They’re all different and divided into groups depending on their specificities. Species diversity is often separated into two categories: a. Intraspecific diversity refers to the genetic variation of individuals and populations of the same species. Humans having white or black skin, blond or brown hair, blue or green eyes is one of the many examples of intraspecific biodiversity. b. Interspecific biodiversity refers to the diversity of living species among themselves: by their number, their nature, and their relative importance. Let’s say humans (or sapiens sapiens), a species with currently 7.7 billion organisms, have a higher diversity than, for instance, the low number of African elephants that are currently facing extinction. 3. Ecosystem biodiversity refers to the variety of ecosystems, by their nature and number, where living species interact with their environment and with each other. For example, on Earth, there are different ecosystems, each with their specificities like deserts, oceans, lakes, plains or forests. Each ecosystem has its own peculiarities, species, and ways of functioning. At each level and between them, interaction is a primordial idea that emphasizes a constantly evolving reality. In fact, biodiversity isn’t limited to the static inventory of living species at a given moment. The assessment of biodiversity and its interactions applies to all types of organisms (plants, animals, bacteria and others) and to the ecosystems of which they’re part and in which they interact. Some terms to remember when talking about biodiversity include population and community. A population is a group of organisms (living things) within a certain area that are all of the same species. A community is comprised of several different populations. Populations can be of the same size, but they may have different densities. The number of individuals in a certain area is called population density. Population density can be calculated as: Number of individuals / Size of area. Factors affecting population density include: 1. When new members move into and out of the ecosystem (migration) 2. Death rate 3. Birth rate 4. Food, water and living conditions 5. Light, temperature and soil nutrients All the factors that affect population density are called limiting factors. These factors help balance an ecosystem. However, the environment’s resources are limited as well. The maximum population size an environment can support is called carrying capacity. B. NATIVE, INVASIVE AND NON-NATIVE SPECIES When discussing about the species of a region, some terms are mentioned. Included are native, invasive and non-native species. The definitions of such terms are mentioned below: 1. The term native species refers to plants and animals that live in a particular area purely by reason of naturally occurring phenomenon. These organisms have not been influenced by any type of human behavior or intervention. a. Indigenous species are categorized as being a type of native species. Rather than being confined to a specific area, indigenous species tend to be more widely dispersed and adaptable. b. Endemic species is also regarded as a type of native species. Endemic species are also known as precinctive. These organisms are only found in certain areas, either large or small in terms of area, and are at an elevated risk of suffering from the possibility of extinction. Examples of endemic species in the Philippines are the Philippine eagle, Negros bleeding heart, Philippine cockatoo, Cebu flowerpecker, tamarraw,  Calamianes deer, Visayan warty pig, Visayan spotted deer, golden-capped fruit bat, Philippine crocodile and Sardinella tawilis. Philippine Negros Philippine Cebu Tamarraw Calamianes eagle bleeding heart cockatoo flowerpecker deer Visayan warty Visayan Golden-capped Philippine Sardinella pig spotted deer fruit bat crocodile tawilis 2. An invasive species is a species of plant or animal that outcompetes other species causing damage to an ecosystem. In the Philippines, we have the cane toad, Chinese soft shell turtle, giant African land snail, golden apple snail, and water hyacinth. Cane toad Chinese soft Giant African Golden apple Water hyacinth shell turle land snail snail 3. A non-native species is a species that originated somewhere other than its current location and has been introduced to the area where it now lives (also called exotic species). C. EXTINCT, ENDANGERED AND THREATENED When the topic is biodiversity, three words are also often mentioned: extinction, endangered and threatened. 1. Extinction is the death of the last surviving individual of a species, population, or gene, locally or globally. A species is said to be extinct if no members of that species are still alive.  2. Being endangered happens when a species’ population becomes so low that only a few remain. There are endangered species in the Philippines like the tamaraw in Mindoro, mouse deer (pilandok) in Palawan, Philippine deer, monkey- eating eagle (Philippine eagle) and dugong. Tamaraw Mouse deer Philippine deer Philippine Dugong eagle 3. Being threatened is the characteristic when a particular species declines so fast that it becomes endangered. There are natural and man-made factors that may cause extinction: NATURAL MAN-MADE Volcanic Activities Deforestation Global Warming Pollution Global Cooling (Ice Age) Destruction of habitat Oxygen Depletion Introduction of Invasive Species Comet/Asteroid Impact Overhunting D. PHILIPPINE BIODIVERSITY The Philippines is one of 18 mega-biodiverse countries of the world, containing two-thirds of the earth’s biodiversity and between 70% and 80% of the world’s plant and animal species. The Philippines ranks fifth in the number of plant species and maintains 5% of the world’s flora. Species endemism is very high, covering at least 25 genera of plants and 49% of terrestrial wildlife, while the country ranks fourth in bird endemism. The Philippines is also one of the world’s biodiversity hotspots with at least 700 threatened species, thus making it one of the top global conservation areas. The 1987 Philippine Constitution, for one, recognizes the right of every Filipino to a balanced and healthful ecology. Among the national laws are: 1. RA 7586, or the National Integrated Protected Areas System (NIPAS) Act; 2. RA 9147, or the Wildlife Resources Protection and Conservation Act; 3. RA 9072, or the National Cave and Cave Resources Management and Protection Act; 4. Presidential Decree 705, or the Revised Forestry Code of the Philippines; and 5. RA 8550 and RA 10654, also known as the Philippine Fisheries Code and Amended Fisheries Code. * * * END * * *