Presentation on theme: "Biodiversity I.What is Biodiversity? A.Levels of biodiversity B.Characterizing biodiversity C.Defining species D.How many species are there? II.Measuring."— Presentation transcript:
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.
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 First pleopods, in resting position, deeply withdrawn between bases of pereiopods and largely concealed by dense setiferous mat extending from ventrolateral margins of sternum (Fig. 7a): Hobbseus Fitzpatrick and Payne, Fig. 7aHobbseus First pleopods, in resting position, never deeply withdrawn between bases of pereiopods and never concealed by dense setiferous mat extending from ventrolateral margins of sternum (Fig. 7b): Orconectes Cope, 1872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).Fig. 7bOrconectes 9(7). Opposable margin of dactyl of chela with abrupt excision in proximal ½ (Fig. 8a): Fallicambarus Hobbs, 1969b (part).7Fig. 8aFallicambarus Opposable margin of dactyl of chela without abrupt excision in proximal ½ (Fig. 8b-e): Cambarus Erichson, 1846 (part).Fig. 8b-eCambarus 7(6). Coxa of fourth pereiopod lacking caudomesial boss (Fig. 6a) Fig. 6a8 Coxa of fourth pereiopod with caudomesial boss (Fig. 6b-d) Fig. 6b-d9 Figure 6Figure 7Figure 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? PhenotypicGenetic 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
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.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 p i ln(p i )] 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 3 Site 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 –
Disturbance & Species Richness Habitat heterogeneity and disturbance Higher 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:
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: Fish Invertebrates Mammals Reptiles Birds