Navigation Links
Traditional models underestimate extinction rates

Last year, the World Conservation Union reported an unprecedented decline in biodiversity, with nearly 16,000 species facing extinction. The biggest threat to most species is loss of habitat. And as habitat loss and degradation proceed nearly unabated, the need to accurately predict the population dynamics and extinction risk of potentially endangered species has never been greater. In a new study, John Drake tests models traditionally used to estimate the likelihood of extinction and shows that because they ignore a critical parameter in projecting risk, they underestimate extinction rates.

Standard models for predicting extinction assume that population growth and decline are governed by random, or stochastic, variables. But few scientists have actually tested the accuracy of these models with empirical data. To do this, Drake first manipulated the available food sources in 281 populations of water fleas, because it's generally assumed that fluctuating environments, a given in the natural world, increase a species's chance of extinction. Drake then used half of the experimental data generated from testing the effects of environmental variability on water flea survival to select his models and estimate a range of parameters that might affect extinction, and the other half to test the models' reliability. From the estimated parameters, Drake wrote a computer program to simulate all the possible population outcomes and predict extinction rates. However, one set of simulations included a parameter for density-dependent random interactions and another did not. The idea is that if organisms interact with each other in their environments--which of course they do--then these interactions will likely affect an individual's probability of dying or reproducing, which ultimately affects species survival. Drake calls this variable density-dependent demographic stochasticity. Only when density-dependence was included did the models match the observed extinction rates in the flea experiments. When density dependence was not included, extinction rates were greatly underestimated.

Drake's results underscore the importance of bolstering extinction models with empirical validation--and of accounting for population density--to accurately evaluate risk and enhance recovery programs for at-risk populations. As threats to endangered species continue to mount, biologists will need ever more robust methods to estimate extinction risk. Unfortunately, field biologists typically can't generate the large, high-quality datasets that led to the precise predictions reported here. Conservation efforts will depend on developing methods of generating reliable predictions with the limited data available from the field.


Citation: Drake JM (2005) Density-dependent demographic variation determines extinction rate of experimental populations. PLoS Biol 3(7): e222.


Source:Public Library of Science

Related biology news :

1. Traditional Chinese medicine for diabetes has scientific backing
2. Molecular models advance the fight against malaria
3. A new way to share models of biological systems
4. Understanding biases in epidemic models important when making public health predictions
5. Gene therapy advance treats hemophilia in mouse models
6. Targeting a key enzyme with gene therapy reversed course of Alzheimers disease in mouse models
7. Elusive salamanders have role in developing new sampling models
8. Computer models aid understanding of antibody-dependent enhancement in spread of dengue fever
9. Sickle cell disease corrected in human models using stem cell-based gene therapy
10. Blocking the nerve receptor EP1 in mouse models reduces brain damage caused by stroke
11. Setting the standard for computer models of life
Post Your Comments:

(Date:11/12/2015)... 2015   Growing need for low-cost, easy ... been paving the way for use of biochemical ... analytes in clinical, agricultural, environmental, food and defense ... in medical applications, however, their adoption is increasing ... continuous emphasis on improving product quality and growing ...
(Date:11/10/2015)... Nov. 10, 2015  In this report, ... basis of product, type, application, disease indication, ... this report are consumables, services, software. The ... safety biomarkers, efficacy biomarkers, and validation biomarkers. ... are diagnostics development, drug discovery and development, ...
(Date:11/9/2015)... Nov. 09, 2015 ... of the "Global Law Enforcement Biometrics ... --> ) has announced ... Enforcement Biometrics Market 2015-2019" report to ... Markets ( ) has announced the ...
Breaking Biology News(10 mins):
(Date:11/30/2015)... San Jose, CA (PRWEB) , ... ... ... the Content Intelligence Company, today announced tighter software integration with MarkLogic, the ... management where organizations maximize information to drive change. , Smartlogic’s Content Intelligence ...
(Date:11/27/2015)... 27, 2015 ... of companion diagnostics is one of the ... with pharmaceutical companies and diagnostic manufacturers working ... . --> ... on global cancer biomarkers market spread across ...
(Date:11/25/2015)... 25, 2015 2 nouvelles études permettent ... les différences entre les souches bactériennes retrouvées dans la ... des êtres humains . Ces recherches  ouvrent une nouvelle ... prise en charge efficace de l,un des problèmes ... chats .    --> 2 nouvelles études ...
(Date:11/25/2015)... ... November 25, 2015 , ... A long-standing partnership between ... (OPBAP) has been formalized with the signing of a Memorandum of Understanding. , ... leaders Capt. Karl Minter and Capt. Albert Glenn Tuesday, November 24, 2015, at ...
Breaking Biology Technology: