BIOL 4120: Principles of Ecology Lecture 8: The Distribution and Spatial Structure of Populations

1. BIOL 4120: Principles of Ecology Lecture 8: The Distribution and Spatial Structure of Populations Dafeng Hui Room: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu

2. Population Ecology Population and Subpopulations (or local populations) A Population consists of the individuals of a species within a given area. Individuals within a population come together and interact with each other, and reproduce, mix the gene pool of the population. A Population consists of the individuals of a species within a given area. Individuals within a population come together and interact with each other, and reproduce, mix the gene pool of the population.

3. Properties of Population Most important property is abundance of population which is determined by its distribution and density. Populations have Distribution: population extent, geographic area occupied by a population (also called geographic range) Population size: Number of individuals in a population (varies with food supplies, predation rates etc.) Population Structure: encompasses a number of attributes, including density and spacing of individuals within suitable habitat and proportions individuals of each sex and age class Density: How to determine population density? Age structures and Different sex ratios along time Changes in distribution and density due to dispersal, emigration, immigration and migration. Distribution and density change in both space and time Changes in distribution and density due to dispersal, emigration, immigration and migration. Distribution and density change in both space and time

4. Topics 10.1 Populations are limited to ecologically suitable habitats 10.2 Ecological niche modeling predicts the distributions of species 10.3 The dispersion of individuals reflects habitat heterogeneity and social integrations 10.4 The spatial structure of populations parallels environmental variation 10.5 Three types of models describe the spatial structure of populations Changes in distribution and density due to dispersal, emigration, immigration and migration. Distribution and density change in both space and time Changes in distribution and density due to dispersal, emigration, immigration and migration. Distribution and density change in both space and time

5. Distribution Spatial location, Area over which a species occupies Geographic range Area that encompasses the entire population of a species Limited by climate Direct: temperature, precipitation� Indirect: Food production Water supply Habitat Incidence of parasites, pathogens and competitors Geographic barriers Scale issue: small, large, whole global?geographic range Biotic, abioticScale issue: small, large, whole global?geographic range Biotic, abiotic

6. The distribution of a species is related to ecological niche Fundamental niche: The range of physical conditions over which species can persist Realized niche: Within the range of conditions, predators, pathogens and competitions limit the distribution of a species to a smaller place Factors influence abundance Due to environmental heterogeneity, populations are divided into local or subpopulations This is the population unit that ecologists usually study A metapopulation is a collection of local subpopulations Factors influence abundance Due to environmental heterogeneity, populations are divided into local or subpopulations This is the population unit that ecologists usually study A metapopulation is a collection of local subpopulations

7. BarnaclesBarnacles

8. Distribution of a species varies at different spatial scales

11. Factors influence species distributions Dispersal limitation Migration Factors influence abundance Due to environmental heterogeneity, populations are divided into local or subpopulations This is the population unit that ecologists usually study A metapopulation is a collection of local subpopulations Factors influence abundance Due to environmental heterogeneity, populations are divided into local or subpopulations This is the population unit that ecologists usually study A metapopulation is a collection of local subpopulations

12. Dispersal limitation Dispersal: movement of individuals in space. Dispersal limitation: the absence of a population from suitable habitat because of barriers to dispersal Methods of dispersal Passive dispersal (gravity, wind, water, animal) seeds of plants, small animals, fish, shrimp. fruits and seeds ate and carried by animals (long distances) Active dispersal: animal movement. Barriers to long-distance dispersal often limit geographic ranges are overcome by human intervention Move plants and animals around the world (invasive species) Dandelions , cherry Human beings: country, stateDandelions , cherry Human beings: country, state

13. Migration � A round trip, perhaps involving mating Red-necked ducks: Breeding in the north east Winter in South Carolina and Florida Gray whale: Winter in California, Summer in Arctic Geographic range of a population includes all the areas of its members occupy during thir entire life history Geographic range of a population includes all the areas of its members occupy during thir entire life history

17. For ecological management purposes (species protection, conservation, new species introduction), we need to understand and predict species distribution Ecological niche modeling: Using exist species distribution knowledge and the related climatic factors to predict actual or potential species distribution under future climate conditions