Lesson 6: Extinction

More biodiversity within an environment, more resilience/adaptations for populations

Extinction

Disappearance of a species, can be ongoing and occur on a small scale over LONG periods of time.

Extinction measurement

comparing the current extinction rate with the background extinction rate (normal/average rate of extinction for species) to assess how quickly species are disappearing compared to historical data.

Cause of mass extinctions

Catastrophic changes to ecosystem → solar flares, rising sea levels, volcanic eruptions.

Downside: species diversity decreases drastically

Upside: speciation occurs much faster because there are more empty ecological niches needing to be filled (adaptive radiation) resulting in evolutionary opportunities.

Speciation and extinction rates determine amount of biodiversity

High levels of speciation and low levels of extinction → HIGH SPECIES BIODIVERSITY

Low levels of speciation and high levels of extinction → LOW SPECIES BIODIVERSITY

The greater the biodiversity…

• multiple food resources

• disease won’t affect ALL, and if wipe out one food there will be other types of food available

• Large population of species

• More places to live

Genetic Diversity in relation to environment pressure

is the variety of genes within a species that enables it to adapt to changing environments. Greater genetic diversity enhances survival and adaptability under environmental stressors.

Resiliency in genetically DIVERSE populations

Will have individuals with a variety of adaptations, the greater the chances it can survive under new environmental pressures.

Alleles can be…

Deleterious traits decreases chance of survival

Adaptive traits increases the chance of survival

it is the unique selective pressure that determines whether a trait is deleterious, adaptive, or neutral in different environments,