1.1 Biodiversity – An Introduction Biodiversity About 1.3 million species have been discovered by scientists. Are there any more species to discover? Diversity YES! New species are discovered daily. It is estimated that there are approximately 8.7 million species on Earth! Biodiversity Biodiversity is the variety of life in the world It is the result of millions of years of evolution as organisms adapt to changes in their environment. Since biodiversity allows systems to change over time to adapt to their changing environment, it is used as a gauge of the health of biological systems. In other words, high biodiversity = healthy system Low biodiversity = unhealthy system What is a Species? General definition: A group who’s members are able to freely breed under natural conditions and produce fertile offspring. Interesting cases: Hybridization Morphology in asexual species Levels of Biodiversity There are three levels of biodiversity: Genetic Diversity Species Diversity Ecosystem Diversity Genetic Diversity Genetic diversity is the sum of all the different forms of genes in a species (gene pool) Due to unique DNA from parents Genetic diversity helps to ensure the survival of a species. How? Genetic Diversity What would be an example of a population with low genetic diversity? What is the downside to this? Species Diversity Refers to the variety and abundance (# of individuals) of species in a given area Having a variety of species allows ecosystems to survive environmental changes such as drought and disease outbreaks Ecosystem/Structural Diversity Refers to the diverse physical sizes and shapes of a habitat, the various organisms that live in the habitats, and the relationships that connect them. Ecosystem Diversity Without the action of each species, the ecosystem and other organisms may not be successful. Ie. Interaction between heterotrophs (animals) and autotrophs (plants) Ecosystem Diversity Each species has a role to play in the function of the ecosystem. Without one of the species, the whole ecosystem could collapse Ecosystem Diversity Biodiversity does not only refer to large ecosystems. 1 cubic meter of soil contains trillions of bacteria and millions of other organisms such as earthworms, mites, fungi, and algae. All of these organisms interact with each other and wouldn’t be able to survive without each other Ecosystem Diversity Humans (and other living organisms) are walking ecosystems! We have about 100 trillion micro-organisms living on us and inside us right now (ie. bacteria in our intestine)…and we need them just as much as they need us! Walking Ecosystem We have developed a symbiotic relationship with the microorganisms that live inside us (unless it’s a pathogen)! The bacteria live in our intestine, and in return they help to break down the food that we consume and keep yeast levels in check. Walking Ecosystem What happens if we disrupt our “walking ecosystem”? Valuing Biodiversity Ecosystems that have high biodiversity are healthier and more resilient to changes in the environment. Biodiversity helps to maintain life-sustaining processes such as: Insects, bats birds, and other animals pollinate flowering plants and crops Micro-organisms make nutrients available and break down toxic substances in water and soil Ecosystems cycle carbon, nitrogen, and oxygen Ecosystems clean air, purify water, control erosion, prevent floods, and modify climate Keystone Species A keystone species is a species that has a disproportionately large effect on the ecosystem in which they live The presence or absence of a keystone species can have a dramatic impact on the ecosystem Case of the Honeybees North America once had more than 4000 different types of native animals that pollinated plants When settlers form Europe brought honeybees, the honeybees outcompeted most of the native pollinators Many of the native pollinators became extinct, leaving thousands of plants reliant on honeybees to be pollinated In one year, a single honeybee can gather 40 lbs of pollen and 265 lbs of nectar Case of the Honeybees Recently, honeybees have been dying at a drastic rate. This is occurring for 3 reasons: Reason #1: Increased use of pesticides is killing all insects, including honeybees Case of the Honeybees Reason #2: The Varroa mite The varroa mite is a parasite that infests beehives and sucks on the bees’ blood until it dies. The mite also carries several bee viruses including the Israeli Acute Paralysis Virus (IAPV) which immobilizes bees and kills them Over time, these mites have become resistant to pesticides, and more powerful pesticides have been needed to control them Case of the Honeybees Reason #3: Bee Farms The increasing industrialization of bee farms has created populations of honeybees that have very similar genes (low genetic diversity). Honeybee populations with similar genes have limited resistance to parasites, poisons, and pollutants Case of the Honeybees Why is the decline of honeybees important? Case of the Honeybees Why is the decline of honeybees important? If honeybees die, the thousands of plants that rely on them for pollination will also die If the flowering plants die, all organisms that feed on these plants would also die. In turn, all carnivores that feed on these herbivores would die Case of the Honeybees Why is the decline of honeybees important? We would have no more: Honey Fruit (except pineapple and bananas) Very little pork and beef products Coffee and cooking oils Medicinal plants Homework Pg. 13 #2,4,6,7,10
