Species DiversitySpecies Diversity

Questions for TodayQuestions for Today

What is Species Diversity?What is Species Diversity? What is the difference between What is the difference between

Species Richness and Species Species Richness and Species Evenness?Evenness?

How Does Species richness affect How Does Species richness affect Biodiversity?Biodiversity?

What is Species What is Species Diversity?Diversity? Species Diversity is the number of Species Diversity is the number of

different species an ecosystem different species an ecosystem contains (contains (species richnessspecies richness) ) combined with the relative combined with the relative abundance of individuals within abundance of individuals within each of those species (each of those species (species species evennessevenness).).– Species Diversity is as major Species Diversity is as major

component of biodiversity.component of biodiversity.

What is Species What is Species Diversity?Diversity? Species Diversity varies with their Species Diversity varies with their

Geographic LocationGeographic Location::– Terrestrial plants and animalsTerrestrial plants and animals

Highest towards the equator and Highest towards the equator and lessens as we head to the poleslessens as we head to the poles

– Aquatic Plants and animalsAquatic Plants and animals Highest where there is more sun Highest where there is more sun

available.available.

Species Richness vs. Species Richness vs. EvennessEvenness A coral reef with many different types A coral reef with many different types

of species but at a low number would of species but at a low number would be described as having high species be described as having high species richness but low evennessrichness but low evenness

A aspen forest with only aspen trees A aspen forest with only aspen trees and a few individuals but at a high and a few individuals but at a high number would be described as having number would be described as having low species richness but high low species richness but high evenness.evenness.

Variations in Species Variations in Species Richness and Species Richness and Species EvennessEvenness

How does Species How does Species Richness affect Richness affect Biodiversity?Biodiversity? High Species Richness creates a High Species Richness creates a

more stable environmentmore stable environment– More ProducersMore Producers

More NPPMore NPP

– More complex food chains and websMore complex food chains and webs Allows organism to adapt to Allows organism to adapt to

environmental stressesenvironmental stresses

– Able to bounce back from Able to bounce back from catastrophes better.catastrophes better.

Niches and Roles

Questions for Today

What is a Niche? What are the differences between Generalist

Species and Specialist Species? What are the different roles Species can play

in the environment?

Ecological Niches

Each species in an ecosystem has a specific role or way of life Ecological Niche = a species way of life or role

in the community Includes everything that affects its survival and

reproduction

Generalist Species vs. Specialized Species Some species have broad ecological roles

and others have narrower or more specialized roles. Generalized species – species that can have

broad niches. Extremely adaptable to a changing environment Flies, Rats, Cockroaches, white-tailed deer,

raccoons, coyotes, humans, and many weeds.

Generalist Species vs. Specialized Species

Specialist species – species that occupy narrow niches. May only live in a certain habitat, use only one type

of food, or tolerate a certain climate condition. More Prone to extinction

Tiger Salamanders – must live in fishless ponds Giant Panda – habitat loss, low birth rate Shorebirds

Is it better to be a generalist or a specialist?

Roles for Organisms

Niches can be divided into the roles species play in their community: Native Non-native Indicator Keystone Foundation

Native vs. Non-native

Native species are those individuals that normally live and thrive in a particular ecosystem.

Non-native species are those individuals that migrate or are accidentally or deliberately introduced to a particular ecosystem. Invasive, alien, or exotic

Native vs. Non-native

Non-native species can be good or bad. Good NN

Cows, chickens, and other domesticated animals Bad NN

Kudzu Vine, Water Hyacinth, and Killer Bees

Indicator Species

When an ecosystem or community starts to collapse, ecologist look at indicator species for the first warning signs.

Indicator species are, generally, specialist species that are affected by a change in one or more key abiotic factors in the environment.

Indicator Species

Examples of Indicator Species: Trout for water quality Birds for air quality Frogs a general measure of productivity in a

region. Tropical Regions

Keystone and Foundation Species

Keystone species have a large effect on the types and abundances of other species in an ecosystem. Keystone species are low in number and are usually

prone to extinctions Extremely important

Two major roles of Keystone Species Pollinator Top Predator

Loss of Keystone Species usually lead to a population crash and other extinctions

Keystone and Foundation Species

Foundation species play a major role in shaping communities by creating and enhancing their habitats in ways that benefit other species. Elephants push over trees and uproot plants

to help new plants take root. Beavers create dams and cut down trees.