1 / 13

Factors Affecting Population Change

Factors Affecting Population Change. Exponential Vs. Logistic Growth. Two Strategies for Growth. 1. “r -strategists”: Spawners! Characterized by exponential growth, which results in temporarily large populations, followed by sudden crashes in population size.

jefferyl
Download Presentation

Factors Affecting Population Change

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Factors Affecting Population Change

  2. Exponential Vs. Logistic Growth

  3. Two Strategies for Growth 1. “r-strategists”: Spawners! Characterized by exponential growth, which results in temporarily large populations, followed by sudden crashes in population size. Ex. Insects, bacteria, some plants • live in unpredictable and rapidly changing environments • Reproduce quickly when conditions are favorable • External Fertilization • Many offspring: small, mature rapidly, no parental care

  4. Two Strategies for Growth 2. “K-strategists”: Brooders! Characterized by a high degree of specialization. Ex. Trees, whales, tigers, etc. • Live in stable and predictable environments • Can compete effectively • Reproduce late in life • Internal Fertilization • Few offspring: large, mature slowly, often much parental care

  5. Density Dependent Factors • Factors that influence population regulation, having greater impact as population density increases or decreases • Struggle for survival includes factors like competition, predation, disease, and other biological effects

  6. Density Dependent Factors • Intraspecific Competition – Ecological interaction where individuals of the same species/population compete for resources in their habitat.

  7. Density Dependent Factors • Predation - Consumption of prey by carnivores • -Regulation can occur due to preferred species of prey

  8. Density Dependent Factors • Disease – Pathogens able to pass from host to host in overcrowded populations with greater ease

  9. Density Dependent Factors • Allee effect – Occurs when population cannot survive or fails to reproduce enough to offset mortality once the population density is too low; such populations usually do not survive. Eg. The extinct passenger pigeon.

  10. Density Dependent Factors • Minimum viable population size – Smallest number of individual needed for a population to continue for a given period of time • Small population size can result in inbreeding and loss of genetic variation

  11. Density Independent Factors • Factors influencing population regulation regardless of population density • Human intervention - Pesticides • Environment - reproductive success based on temperatures, natural disasters etc

  12. Limiting Factors • Any essential resource that is in short supply or unavailable. These factors determine how much the individual or population can reproduce. • Eg. light, space, water, nutrients

  13. Homework! • Page 675 1, 2 & 5 • Read 676-687

More Related