Biodiversity

I. What is Biodiversity?A. Levels of biodiversity

B. Characterizing biodiversity

C. Defining species

D. How many species are there?

II. Measuring Biodiversity

III. Patterns of Biodiversity

IV. Ecological components of Biodiversity

V. Biodiversity Crisis

I. What is Biological Diversity?

“the millions of plants, animals, and microorganisms, genes they contain, and the intricate ecosystems they help build into the living environment” (World Wildlife Fund, 1989)

“Biodiversity" also has served on occasion as a catch-all for "conservation" itself.

Taxonomic Hierarchy

       

  Kingdom Animalia  -- animals  

     Phylum Arthropoda  -- arthropods  

        Subphylum Crustacea Brünnich, 1772 -- crustaceans  

           Class Malacostraca Latreille, 1802  

              Subclass Eumalacostraca Grobben, 1892  

                 Superorder Eucarida Calman, 1904  

                    Order Decapoda Latreille, 1802 -- crabs, crayfishes, lobsters, prawns, shrimp  

                       Suborder Pleocyemata Burkenroad, 1963  

                          Infraorder Stenopodidea Claus, 1872  

                             Superfamily Astacoidea Latreille, 1803  

                                Family Cambaridae Hobbs, 1942 -- crayfishes  

                                   Genus Fallicambarus Hobbs, 1969  

                                      Species Fallicambarus devastator Hobbs and Whiteman, 1987 -- Texas prairie crayfish  

   

 

B. Characterizing Biodiversity

NOMENCLATURE:

IDENTIFICATION AIDS

8(7).   First pleopods, in resting position, deeply withdrawn between bases of pereiopods and largely           concealed by dense setiferous mat extending from ventrolateral  margins of sternum (Fig. 7a):           ............................................................................................................... Hobbseus Fitzpatrick and Payne, 1968.

       First pleopods, in resting position, never deeply withdrawn between bases of pereiopods and    never concealed by dense setiferous mat extending from ventrolateral margins of sternum    (Fig. 7b):  ......................................................................................................Orconectes Cope, 1872 (part).

9(7).   Opposable margin of dactyl of chela with abrupt excision in proximal ½ (Fig. 8a):............................            ..................................................................................................................... Fallicambarus Hobbs, 1969b (part).

       Opposable margin of dactyl of chela without abrupt excision in proximal ½ (Fig. 8b-e):...............    ....................................................................................................................... Cambarus Erichson, 1846 (part).

7(6).   Coxa of fourth pereiopod lacking caudomesial boss (Fig. 6a)...................................................................    8

       Coxa of fourth pereiopod with caudomesial boss (Fig. 6b-d) ...............................................................     9

Figure 6 Figure 7 Figure 8

1) Biological Species Concept

2) Evolutionary/Phylogenetic Species Concept

3) Morphospecies Concept

4) Evolutionary Significant Unit

Testing an hypothesis that a set of populations is a single species is important to conservation management. Sets of recognized species often form the basis for surrogates for geographic priority setting.

1. BCS• Proposed by Ernst Mayr, 1942

• Legal definition employed in the Endangered Species Act

• Criteria =

• Confirms the lack of gene flow, thus showing evolutionary independence

2. ESC• First proposed by G.G. Simpson, 1961

• Criteria =

• Populations must have been evolutionarily independent long enough for diagnostic traits to emerge

• Species are named on the basis of statistically significant differences in the traits used to estimate the phylogeny

3. MSC

• Criteria =

• Good to use for fossil specimens

Problems:Doesn’t account for behavioral or genetic differences evident in cryptic species

The skull on the left is from the Peloncillo Mts., west of the Rio Grande in New Mexico near the Arizona border. The skull on the right is from the Franklin Mts. of Texas, east of the Rio Grande. Molecular evidence now indicates that these are two separate species despite the great

morphological similarity.

ESU & the genetic species concept• Determining what to conserve (distinct

evolutionary units) is oftentimes very difficult

• How do you account for genetic diversity below the “species” level?

Phenotypic Geneticdifferences differences

Natural selection Historical Isolation

Canis rufus

Canis latrans

D. How many species are there?

Determining the actual # impossible…

Species richness in major groups of organisms. The main 'pie' shows the species estimated to exist in each group; the hatched area within each slice shows the proportion that have been formally described. Nature 2000 v405

II. Measuring Biodiversity

A. Species richness

B. Alpha diversity

C. Beta diversity

D. Gamma diversity

E. Diversity Indices Shortcomings

A. Species richness [S]

• Number of different species

Endemism –Ecological distinctiveness of different

species, e.g., functional differentiation Evolutionary distinctiveness of different

species

http://www.okstate.edu/artsci/botany/bisc3034/lnotes/specare2.jpg

B. alpha diversity

• # of species in a certain community, “the species richness of standard sample sites”

Equitability, Evenness [E]

Diversity index = mathematical measure of species diversity in a community. Provides more information about community composition than simply species richness

• Simpson Index - It takes into account the number of species present, as well as the relative abundance of each species. It represents the probability that two randomly selected individuals in the habitat belong to the same species.

– 1 – D, the index represents the probability that two individuals randomly selected from a sample will belong to different species

• Shannon Diversity Index – takes into account the proportional abundance of different species and the eveness.– [H’ = -∑i pi ln(pi)]

most widely used index in community ecology The higher the number the greater the diversity

C. Beta diversity• diversity associate with changes in sample

composition along an environmental gradient

• Measures the rate of change in species composition across a landscape

• S/α – 1

• Can determine the following

Region X

Region Y

Site 3Site 4

Site 1

Site 2

D. Gamma diversity

• Used to compare large areas that encompass diverse landscapes or a wide area

• landscape scale where diversity also controlled by site-to-site variation in ecological controls, disturbance regime, habitat diversity, dispersal

E. Diversity Indices Shortcomings

1) Richness & evenness can be inversely related

2) Mathematical measures don’t correspond to ecological importance

• All species are treated as “equal”• value of the species in the ecosystem not

correlated

III. Patterns of Biodiversity:

A. Species-Area Relationship

• Direct relationship between species richness and area

• The number of species on an island is a constant power of the island’s area

Patterns of Biodiversity:

B. Global Patterns

• Species distribution affected by several factors:

Spatial Patterns in Species Richness

Nature 2000 v.405

earthworms

Lacustrine fishes

birds

bats

Woody plants

Patterns of Biodiversity:

C. Regional Trends in Diversity Marine environments –

Freshwater wetlands highest in temperate landscape

Edge –

Biodiversity “HOT SPOTS”

http://www.biodiversityhotspots.org/xp/Hotspots/

Additional Considerations

Habitat generalistsHabitat specialistsEndemism and rarityDisturbance

Disturbance & Species Richness

• Habitat heterogeneity and disturbanceHigher heterogeneity =

• Diversity-Stability Rule –

• in a more variable environment selection forces come from physical environment…more stable environment, selection forces are largely biotic - competition

Why do we need to study biodiversity?

• Ecological Value:– Biodiversity actually boosts ecosystem productivity &

functionality where each species, no matter how small, all have an important role to play and that it is this combination that enables the ecosystem to possess the ability to prevent and recover from a variety of disasters.

– Ecological components of biodiversity

IV. Ecological components of biodiversity

A. Functionality:

B. Productivity –

Biodiversity is linked to productivity is linked to biodiversity????

The more resources available (nutrients, plants or prey species)

The more energy

A greater number of

VI. Biodiversity Crisis

• Part of the natural cycle, precedes speciation events

• Problem?

• Rates of extinction v. speciation

• Current rates of extinction:

Mass extinctions through time – (62 million year periodicity)

Threatened animal species:

Amphibians

Already extinct:

From the 2004 World Conservation Union Study:

http://www.iucnredlist.org/

Fish

Invertebrates

MammalsReptiles

Birds