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Ch. 18 Part 1 Species • A group of organisms with similar morphology and physiology, which can breed together to produce fertile offspring that are reproductively isolated from other species – 1.5 million animal species – 250,000 flowering plant species – Exact number of different spies (including ALL 3 domains of life) unknown • Places that have remained unexplored • Disagreements on divisions of species among scientists • Estimates range up to 100 million • Binomial Nomenclature – – – – 2-name naming system Carolus Linnaeus, 18th century Name a species using Genus and species Examples: • • • • Homo sapiens (H. sapiens) Pantera leo (P. leo) Canius lupus (C. lupus) Canius domestitcus (C. domesticus) Ecosystem • • Relatively self-contained, interacting community • of organisms and the environment they live in and in which they interact • Includes biotic and abiotic factors – – Biotic living factors/interactions Abiotic non-living factors • • • • • Soil Leaf litter Humidity Temperature Different scales or levels – – Simple desert Complex tropical rainforest Habitat Place where an organism lives within an ecosystem Niche – The role an organism plays in an ecosystem – More than a physical description of a place – How the organism “fits” into ecosystem • Describes: – Where organism is in ecosystem – How it obtains energy – How it interacts with physical environment – How it interacts with other species – Niche for large, herbivorous animals • Australia vs. Africa – Different species can occupy similar niches because they feed off of different vegetation – Impossible to completely describe a niche because there are so many ways in which one organism can interact with the other components of the ecosystem which it is part of Diversity • “catalogue of different species” • Rich in different species • Most biodiverse ecosystems – Tropical forests – Coral reefs • Biodiversity – Degree of variation of life forms in an ecosystem – Three levels: 1. The variation in ecosystems or habitats (Ecosystem Diversity) 2. The number of different species in an ecosystem and their relative abundance (Species Diversity ) 3. The genetic variation within each species (Genetic Diversity) • • • Species Diversity A measure of species richness in a community and the evenness of the abundance of the different species The more species AND the more evenly the number of organisms are distributed among different species = increased species diversity Ecosystems with high species diversity = more stability than ecosystems with limited diversity – • Ecosystems with less extreme conditions = more species diversity – • More resistant to changes Tropics vs. the tundra/desert Ecosystems dominated by one or two species are rare – – Pine forests in Florida Temperate forests in Canada • Genetic Diversity Provides populations with the ability to adapt to changes in biotic and abiotic factors • Definition: – Diversity of alleles within the genes in the genome of a single species • All individuals of species have the same genes but NOT necessarily the same alleles • Assessed by determining what proportion of genes have different alleles and how many alleles per gene • Genetic differences between populations of same species due to adaptations in different ranges – Geographic Range: location in which that species is distributed • boundary beyond which a species does not occur, the limit or limits of the range of a species – Important for adaptation to environment (biotic and abiotic factors) Assessing Species Diversity • To determine species diversity: – Observation skills important – Identify and catalogue types of organisms in an ecosystem – Build a species list – Use identification keys to name the species collected • Drawings/photos with IDs • Question maps • Dichotomous keys – Used to identify and differentiate between a variety of species Dichotomous Key Collecting and Identifying Species • Timed search in area to collect and ID as many species as possible • Unable to ID = take pics and label species A, B, C, etc. – Use pics with reference materials to ID later on • Hard to collect species – Use special collection tools • “pooter” – Use magnifying glass/hand lens to analyze more closely and ID