1 / 17

Population Changes

Population Changes. Distribution Patterns are Fluid. Distribution Patterns are Fluid. For each population, the distribution pattern is a product of complex interactions between behaviours and other characteristics that increase each individuals chances of reproduction and survival.

ivi
Download Presentation

Population Changes

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. Population Changes Distribution Patterns are Fluid

  2. Distribution Patterns are Fluid • For each population, the distribution pattern is a product of complex interactions between behaviours and other characteristics that increase each individuals chances of reproduction and survival • http://www.appinsys.com/globalwarming/GW_4CE_Animals.htm http://www.rarwriter.com /PublicPolicyandPolitics_2.htm

  3. Review of Distributionhttp://roadtravelafrica.com/2010/11/26/meerkats/ http://blog.webosaurs.com/2011/02/09/wolverines-disappearing-from-the-us/ Ex. #2 Wolverines – territorial in an area with evenly distributed food Ex. #3 Tropical Fig – seeds are randomly distributed in tropical rain forests ** this type of distribution is very rare Ex. #1 Meerkats – live in groups gathered near resources

  4. Immigration, Emigration, Natality & Mortality ΔN = [B+I]- [D+E] How Populations Change Size

  5. Immigration vs Emigration Immigration Emigration The movement of individuals out of a population • The movement of individuals into a population • For most species immigration/emigration has little impact on population size • Exception include human populations (we move more than is typical for a species) and invasive species such as zebra mussels • Open populations have immigration/emigration, • closed populations do not! • http://www.cloca.com/lwc/streams_invasive.php • http://www.awdalpress.com/index/?attachment_id=15131

  6. Natalityvs Mortality Natality Mortality Death http://www.treehugger.com/natural-sciences/forest-death-rates-doubled-on-the-west-coast.html • Birth • http://favim.com/image/68983/ • As the population density increases, birth rates often decrease and death rates typically increase • Since most populations are not greatly effected by immigration/emigration: • ΔN = B-D EX. In a population of slow loris, 24 were born • Δ → change and3 died the population size is: • N → population size • B → births ΔN = B-D ΔN = 24 - 3 • D → Deaths ΔN = 21

  7. Aspects of Natality Fecundity, Survivorship, r- and k- selected strategies

  8. Fecundity • The average number of offspring produced by a female over her lifetime • This tends to be inversely related to the amount of care a parent provides • Ex. Turtles have a high fecundity, while gorilla’s have low fecundity http://www.chinadaily.com.cn/photo/2007-09/22/content_6126743_4.htm http://scienceblogs.com/zooillogix/2008/08/05/are-you-hiding-125000-western/

  9. Survivorship • The number or percentage of organisms that typically live to a certain age in a given population • Type I shows a high rate of rate of juvenile survival and individuals that live to sexual maturity and beyond EX. Humans • Type II shows a constant risk of mortality throughout an individuals lifetime EX. squirrels • Type III most individuals die as juveniles, only a few live long enough to produce offspring, and fewer live to old age EX. oysters • http://mycozynook.com/102RGCh36OH.htm

  10. r- and k- selected Strategies r- selected strategy K- selected strategy Live a relatively long life span Become sexually mature later in life Produce few offspring per reproductive cycle Provide a high level of parental care • Short life span • Become sexually mature at a young age • Produce large broods of offspring • Provide little or no parental care to their offspring • Most populations fall somewhere between these two strategies • Describing if a population is r-selected or k-selected requires that it be compared to another population

  11. Population Growth Models Unlimited and Limited Environments

  12. Biotic Potential • The highest possible per capita growth rate for a population • AKA intrinsic rate of natural increase (r) • A species’ biotic potential is related to its fecundity • http://www.underwater.org/mermaid/tanzania/underwater3.html

  13. Unlimited Environment Exponential Growth Model Geometric Growth Model Deaths can occur throughout the year, but births are restricted to a breeding season Sampling occurs on a yearly (usually) basis • Births and deaths can occur throughout the year, (no fixed breeding season) • Sampling can be continuous EX. Humans EX. Sparrows

  14. J-shaped Growth Curve • This graph traditionally represents exponential growth • At the bottom there is a lag phase followed by an exponential growth phase

  15. Limited Environments: Carrying Capacity • Carrying capacity is the maximum population size that a habitat can sustain over an extended period of time • At this point the birth and death rates are approximately equal • http://www.hunter-ed.com/az/course/ch9_carrying_capacity.htm

  16. Limited Environments: Logistic Growth • Logistic Growth is the growth pattern exhibited by a population for which growth is limited by carrying capacity, or limited availability of resources • Populations that achieve logistic growth are represented by a sigmoidal or s-shaped curve • http://gcevoices.com/ep/2012/02/10/using-logic-for-problem-solving/

  17. THE END

More Related