Zoology 101: Animal Biology Last Lecture Outline Lecture 38 1. Allopatric and Sympatric Speciation2. Adaptive Radiation and Mass extinctionsCurrent Lecture 1. Ecology2. Dispersal and Distributions3. Population EcologyEcology• Ecology: the study of distribution and abundance of organisms • What determines where a species is located?◦ Species present depends on past/current positions▪ can a species get there? (Dispersal)▪ once it's there ,can it survive• evolutionary time scale: decades → millions of years • ecological time scale: hours → years • Biogeography:◦ study of species distribution (emphasis on historical events and difference between past and present patterns of distributions◦ Results of evolution apparent over time, and also over space ◦ Historical events in earth’s history had strong effects on distribution of species ▪ plate tectonics ◦ Continental Drift▪ earth's crust is dynamic in geological time▪ Evidence of original “supercontinent” of Pangaea in fossils as well as extant taxa Dispersal and Distribution• Dispersal: movement of individuals away from centers of high population density or their area of origin◦ can happen due to natural movement of organisms◦ Can happen due to human activities (species introduction, translocations)• Kinlan and Gains (Ecology 2003)◦ the scale of natural dispersal is highly variable among taxa and groups◦ herbivores often disperse further than plants◦ Dispersal of propagules in marine systems consistently exceeds terrestrial plants • Behavior and Habitat selection◦ some organisms do not occupy all of their potential range◦ species distribution may be limited by habitat selection behavior• Biotic factors◦ predation, parasitism, competition, disease• Abiotic factors◦ water, oxygen, salinity, pH, soil nutrients, temperature, light, soil, fire, moisture ◦ Climate: long term, prevailing weather pattern▪ temperature, precipitation, seasonality of conditions▪ creates different Biomes• characteristic type of ecological community associated with particular climate• 2 variables: temperature and precipitation• rain forest, desert, savanna, chaparral, grassland, mountain ranges, tundra, different types of forests• Scope of ecological research ◦ ecologist work at levels ranging from individual organisms to the planet◦ There are several sub-disciplinary within ecology▪ organismal, population, community, ecosystem, landscape, global ecology Population Ecology• explores how biotic and abiotic factors influence density, distribution, size, age and structure of populations• Population: group of individuals of same species that live in the same area • Characteristics of Interest ◦ Density: number of individuals per unit area or volume ◦ dispersion: patter of spacing among individuals in a populations • Density Factors◦ Birth: positive influence ◦ Immigration: positive influence◦ Death: Negative influence◦ Emigration: negative influence ◦ Dispersion Patterns▪ Clumped: aggregate in patterns, due to resource availability, social behavior, mating opportunity ▪ Uniform: evenly distributed, strong territoriality, social interaction, competition▪ Random: position of individual is independent of other individuals, occurs in the absence of strong interactions and
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