The Diversity of Living Things Biodiversity • When scientists speak of the variety of organisms (and their genes) in an ecosystem, they refer to it as biodiversity. • A biologically diverse ecosystem, such as an old growth forest or tropical rain forest, is healthy, complex and stable. • Nature tends to increase diversity through the process of succession. Biodiversity • The opposite of biodiversity is referred to as monoculture, or the growing of one species of organism, such as a lawn, a wheat field or corn field. • All of the species are identical, there are few complex food webs and disease can spread quickly. • Monoculture is like a banquet table for disease organisms. Monoculture often requires extensive use of pesticides and herbicides (to fight nature's tendency to diversify communities) and is very labor and energy intensive (fighting nature is tough). • Humans often try to reduce diversity because it is easier to harvest a crop (whether it is wheat, corn , a lawn or a secondary forest) if it all contains the same species, but this obviously creates serious problems. Diversity of Living Things - Introduction Biodiversity generally refers to the number and variety of species, the diversity of genes of the species and all of Earth’s different ecosystems. The three levels of diversity: 1)Species Diversity – refers to the number of species and their relative abundance. All species within an ecosystem have an important role in maintaining other species but also support the physical environment (preventing erosion), provide resources (food, lumber) and even support our social needs (research). How does one species within an ecosystem influence another? Make notes from Table 1 p. 11 • Food supply • Protection • Transportation • Reproduction • Hygiene • Digestion 4 2) Genetic Diversity -Individuals in a population show variation because they have different combinations of genes and genetic mutations. This is essential for species’ survival as environments change (for ex. A new infection kills some individuals while others survive – this allows the species to continue to survive). 3) Ecosystem Diversity – Ecosystems vary in their physical shapes and sizes and diversity of species present. Organisms tend to thrive in ecosystems with ‘structural diversity’. It is important to maintain our environment as pollution or removal of resources (mining) destroy the ecosystem. 5 The Anthropocene • A term to describe the recent geological time period during which time humans have caused a major change to the planet. • Humans have changed the climate, reduced biodiversity and altered many ecosystems. The last mass extinction occurred 65 m.y.a.; many researchers think the Anthropocene marks another mass extinction. Here are four examples of threats to biodiversity: 1. Habitat destruction – single greatest threat 2. Introduced (invasive) species – throw off ecosystem balance and disrupt community 3. Overexploitation – consumption of plants or animals at a rate that exceeds the ability of the species to rebound 4. Disruption of Interaction Networks – domino effect whereby the extinction of one species dooms others 6 Why does the loss of biodiversity matter? Moral argument – respecting the life of other species is a key part of many religious and/or ethical belief systems Crucial natural resource for humans in terms of crops, fibres, medicines, etc. For example: 25% of prescriptions contain plant-derived substances Ecosystem services - all the processes through which natural ecosystems and the species they contain help sustain and maintain life on Earth e.g. purification of air and water, reduction in the severity of droughts and floods, decomposition of wastes, pollination of crops, cycling of nutrients, provision of beauty and recreational opportunities etc. 7 Review Biodiversity includes: 1. Species diversity 2. Genetic diversity 3. Ecosystem diversity Biodiversity is at risk! 8 The Six Kingdoms • • • • • • Archaebacteria Eubacteria Fungi Protists Plants Animals Archaebacteria Characteristics • • • • Single-celled lack nuclei reproduce by dividing in half found in harsh environments Archaebacteria Examples • Methanogens • Thermophiles Eubacteria Characterstics • • • • Single-celled lack nuclei reproduce by dividing in half incredibly common Eubacteria Examples • Proteobacteria (common in soils) • Cyanobacteria (blue green algae) Fungi Characteristics • • • • • Absorb their food through body surfaces have cell walls most live on land no chlorophyll decomposers Fungi Examples • • • • Yeast mushrooms molds mildews Protists Characteristics • Most single-celled • most live in water Protists Examples • • • • Diatoms amoeba Paramecia Algae (smallest: phytoplankton, largest: giant kelp) Plants Characteristics • Many celled • make own food through photosynthesis • have cell walls Plant Examples • • • • • Ferns mosses trees herbs grasses Two Classes of Plants • Gymnosperms: woody plants whose seeds are not enclosed in fruits. Examples: pine trees and evergreens. • Angiosperms: flowering plants that produce fruit. Examples: grasses, wheat, rice, beans, cotton, flowering plants Animal Characteristics • • • • Many cells no cell walls ingest their food live on land and in water Animal Examples • • • • • • • • Corals sponges worms insects fish birds reptiles mammals Two Animal Classes • Invertebrates • Vertebrates Invertebrates • Animals that lack a backbone. Examples: squid, corals, mollusks, worms, insects • Insects: more on earth than any other type of animal. Why? Why so successful? • Waterproof external skeleton, move quickly, reproduce quickly, most can fly, small size allows then to live on little food and hide in small spaces. Vertebrates • Animals that have backbones. Examples: reptiles, mammals, birds, amphibians • Mammals: warmblooded vertebrates, fur, feed their young.
