Taxonomy and Systematics: a broader classification system that also shows evolutionary relationships

Transcription

1 Taxonomy: a system for naming living creatures Carrolus Linnaeus ( ) The binomial system: Genus and species e.g., Macrocystis pyrifera (Giant kelp); Medialuna californiensis (halfmoon) Taxonomy and Systematics: a broader classification system that also shows evolutionary relationships A Hierarchical system: Genus Family species Kingdom Phylum Class Order 5 Kingdom system: a system that considers structure and complexity as well as other characteristics including metabolic strategies. 3 Kingdom system: K. Bacteria K. Archaea K. Eukarya Old 5 Kingdom Classification 3 Domain Taxonomy of life Taxonomy The Taxonomic Naming System 1

2 Comparative Anatomy: Cladistics and taxonomy Figure 25.8 The connection between classification and phylogeny What are species? Reproductive Barriers Biological Species Concept Group of reproducing individuals Groups of interbreeding natural populations that are reproductively isolated from other such groups Morphological S. C. Groups of same looking things Phylogenetic S. C. Group of individuals distinct in their ancestry and descent Other S. C What is a Species? Biological Species Concept defines species as groups of interbreeding natural populations that are reproductively isolated from other such groups Speciation Allopatric Speciation 2

3 Gradual or Punctuated? Horse Evolution Patterns of Evolution The cone of increasing diversity vs. the model of decimation and diversification Biodiversity and Its Threats Decimation and Diversification Conservation Biology Goal-oriented science that seeks to counter the current rapid decrease in biodiversity The Biodiversity Crisis- human activities alter ecosystem processes, alter landscape and trigger extinctions Three Levels of biodiversity Genetic diversity Species diversity Habitat / Community diversity 3

4 Three Levels of biodiversity Genetic diversity Variation within and between populations Genetic diversity allows for adaptation to changing conditions If populations loose genetic diversity they loose adaptive ability Once genetic diversity is lost it takes evolutionary time to get it back Three Levels of biodiversity Species diversity Loss of species richness 13% of 9,040 bird species threatened 47% of all plants worldwide threatened 20% of freshwater fish extinct or threatened Since 1900, 123 extinct freshwater vert and inverts in North America alone Many animals are in the Hundred Heartbeats club Three Levels of biodiversity Habitat / Community Diversity Extinction of one species could have negative impact on others in the system Each system can have an important impact on the whole biosphere Benefits of diversity Anthrocentric Species are a natural resource for food, fibers, medicines, etc. Do all species have an innate value? Are some worth more than others? Who decides? Ecosystem services Often overlooked benefits to humans: Air, water, soil, detoxification, decomposition, pollination, seed dispersal, nutrient cycling, protection from UV, moderation of weather aesthetic beauty and infinite source of wonder Estimated at $33 trillion/year (1997)- 2x global GNP 1. Habitat destruction 2. Introduced species 3. Overexploitation 4. Disruption of food chains 1. Habitat destruction Single greatest threat to biodiversity Over 70% of extinct, endangered, threatened species from loss of habitat 93% of reefs are damaged- 1/3 of fish species are in coral reefs which make up only 0.2% of ocean. Large variety of human uses impact habitat loss Living, food, recreation, materials, fuels, etc Landscape fragmentation Habitat size is not the only issue, contiguous pieces are also important 4

5 Habitat fragmentation 2. Introduced species Second biggest problem- linked to 40% of extinctions Exotic species - species humans have moved from one location to another, sometime intentionally, sometimes not Successful exotics often disrupt their new community, prey on and/or compete with native species 50, 000 in U.S. alone, damage control ~ $137 billion/year Some examples Carcinus maenas- Green Crab First collected on west coast in S.F Moved to Bodega Bay by 1993 Found in Monterey by 1994 Green Crab Invasions Invasion of North America by the European green crab US East Coast s s s s 1989 a voracious predator on native bivalves and crustaceans West coast invasion US West Coast 5

6 3. Overexploitation Human harvesting of plants and animals exceeds ability of populations to rebound Species especially susceptible are those with low reproductive rates The inexhaustible seas Fishing down the food web MBA Seafood watch 4. Disruption of food chains Loss of one species in an ecosystem can have negative impacts on there species Remove the prey, the predators will suffer Since most organism do not depend on just a single prey species, this can be a very difficult thing to quantify? BIOMES Biomes - Areas sharing similar climate, topographic and soil conditions, and roughly comparable communities. Temperature and precipitation are among the most important determinants in biome distribution. Evapotranspiration Influenced by prevailing landforms. Biomes World Biomes 6

7 Aquatic Biomes Land-linked Aquatic Biomes Lakes Rivers Streams Wetlands Estuaries Aquatic Biomes Wetlands Land surface is saturated or covered with water at least part of the year. Swamps - Wetlands with trees. Marshes - Wetlands without trees. Bogs and Fens - Waterlogged soils that tend to accumulate peat. Water usually shallow enough to allow full sunlight penetration. Trap and filter water, and store runoff. Estuaries Bays or semi-enclosed bodies of brackish water that form where rivers enter the ocean. Usually carry rich sediments. Fan-shaped sediment deposit (delta) formed on shallow continental shelves. Intertidal Coral Reefs Oceanic Marine Biomes Many different organisms Warm, clear water Zooxanthellae Coral Reefs 7