Measuring and Monitoring Biodiversity. Outline. What is biodiversity? The challenges of defining a species How many are there? Measuring biodiversity at the species level. What is biodiversity?. What is a species?. Two conflicting viewpoints. Biological Species Concept (BSC).
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Outline • What is biodiversity? • The challenges of defining a species • How many are there? • Measuring biodiversity at the species level
What is a species? Two conflicting viewpoints
Biological Species Concept (BSC) • Key criteria? • Most frequently used definition today • Simple, clear rules Weaknesses?.
Ecological Species Concept • Set of organisms adapted to a particular set of resources, called a niche, in the environment (Ridley 1993) • Relates to the actual role species play in the environment
Phylogenetic Species Concept (PSC) • Smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent (Cracraft 1983) • Based on concept of synapomorphy • Requires Monophyly • Weaknesses?
Time Reciprocal monophyly Example: Red = N Idaho GS Green = S Idaho GS
Empirical Example • Two species • Classified as separate by typologists • Morphology- not even close • Ecology- occupy very different niches • Geography- ranges overlap little, are adjacent in some areas However…
Example • Hybridize and produce viable offspring • Paraphyletic • mtDNA Waits et al. 1998
Should the mystery organism be a unique species? What do you think?
Implications • Lumpers vs. splitters • Agapow et al. (2004) • Examined previous studies of organisms classified under PSC and non-PSC • Using PSC resulted in 49% increase in # of spp.
Brown et al. 2007 • Giraffe phylogenetics • Discovered six potential species • Captive breeding programs in limbo
Jody Hey (2001)- Species “are the results of two processes: 1. the evolutionary processes that have caused biodiversity and 2. the human mental apparatus that recognizes and gives names to patterns of recurrence.”
How many species? • 1.75 million living and 300,000 fossil species have been described • Estimates range from 10 to 50 mil (May 1988, Wilson 1992, Gaston and Spicer 2004) • So only 3.5% - 17.5% are described • And most are? • 300 new species described per day!
Bacterial Biodiversity (Torsviks et al 1990) • Took 1 gm of Norwegian forest soil and 1 gm of Norwegian ocean soil • Extracted bacteria and bacterial DNA • Assumed different species if < 70% DNA sequences matched • Estimated 4000 species in each gram • Note: only 4760 are currently described
2006 CI Expedition to Bird’s head seascape - Indonesia • How many new species?
# species? • Basically, we have no idea. • It is clear that many will disappear before they are discovered or named. • 11 of the 80 known species of whales and porpoises were discovered in 20th century • In past 10 years, 3 new families of flowering plants were discovered in Central America • One new phyla (Cycliophora) was discovered in the sea in 1995
How do we measure species diversity? What are the 3 main scales of measurement for diversity?
Alpha • Species diversity within an ecological community or region • Richness = • Diversity Estimators (Table 4.3) • Shannon Index H’= -∑pi*ln(pi) pi=proportion of each species in community • Simpson’s Index D= 1/∑pi²
Evenness • Note- your book is confusing. It refers to diversity indices (pg. 91) as measures of evenness. • However, to calculate ‘evenness’ for any given site, you need to divide an observed diversity value by its maximum possible value. • To use the example of the Shannon index, Evenness = H’/Hmax
Beta • Diversity of species among communities • Rate of species change along a gradient • Dissimilarity index (# unique spp./total spp.) • Can be calculated across all sites (see discussion of Whittaker’s statistic in your text), or as pairwise comparisons Butternut Creek, NY
1) Estimate species richness for each2) Calculate Beta Diversity3) Which site has the lowest diversity/evenness? Which site has the highest?
Gamma • Diversity of species among larger landscape levels • Diversity of kinds of communities within a landscape • Compares differences among communities (rate of change) across large geographic scales
Is more always better? Clear lake, California 13 native fish species Now 24 fish species
Are all species equal? Should we be just counting species? What about uniqueness? How do we prioritize?
Endemism • Endemics • Restricted to a particular area or region • Matter of perspective • What types of areas have high endemism? Idaho Ground Squirrel
What are important patterns of biodiversity at the species level? • What are important biodiversity processes at the species level?